References - INFLIBNETshodhganga.inflibnet.ac.in/bitstream/10603/14122/14/14_reference.pdf · 144...

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References

[1] Muller. O, Roy. R, (1974), The Major Ternary Structural Families, Springer-

Verlag, New York.

[2] Chang Sung. L, J. Ceram. Process. Res, 12, (2011), 544.

[3] Cavalcante. L. S, Sczancoski. J. C, Lima. L. F, Espinosa. J. W. M. Jr, Pizani. P. S,

Varela. J. A, Longo. E, Cryst. Growth. Des, 9, (2009), 1002.

[4] Zalga. A, Moravec. Z, Pinkas. J, Kareiva. A, J. Therm. Anal. Calorim, 105,

(2011), 3.

[5] Sulawan. K, Titipun. T, Somchai. T, J. Ceram. Process. Res, 11, (2010), 432.

[6] Xiufeng. Z, Teresa. L. Y. C, Xitian. Z, Dickon. H. L. Ng, Jiaguo. Yu, J. Am.

Ceram. Soc, 89, (2006), 2960.

[7] Kisla. P. F. S, Roberto. L. M, Marcelo. V, Anderson. D, J. Mater. Sci, 45, (2010),

6083.

[8] Basiev. T. T, Sobol. A. A, Voronko. Y. K, Zverev. P. G, Opt. Mat, 15, (2000), 205.

[9] Won-Chun Oh, Jong Guen Choi, Chong Yeon Park, Chang Sung Lim, J. Ceram.

Process. Res, 12, (2011), 435.

[10] Basiev. T. T, Sobol. A. A, Zverev. P. G, Ivleva. L. I, Osiko. V. V, Powell. R. C,

Opt. Mat, 11, (1999), 307.

[11] Chang Sung Lim, Kyoung Hun Kim, Kwang Bo Shim, J. Ceram. Process. Res, 12,

(2011), 727.

[12] Sofronov. D. S, Sofronova. E. M, Starikov. V. V, Baymer. V. N, Kudin. K. A,

Matejchenko. P. V, Mamalis. A. G, Lavrynenko. S. N, Mater. Manuf. Processes,

27, (2012), 490.

[13] Zhang. G, Jia. R, Wu. Q, Mater. Sci. Eng. B, 128, (2006), 254.

145

[14] Kloprogge. J. T, Weier. M. L, Duong. L.V, Frost. R. L, Mat. Chem. Phys, 88,

(2004) 438.

[15] Phuruangrat. A, Thongtem. T, Thongtem. S, Curr. Appl. Phys, 10 (2010) 342.

[16] Phuruangrat. A, Thongtem. T, Thongtem. S, J. Cryst. Growth, 311 (2009) 4076.

[17] Thongtem. T, Kaowphong. S, Thongtem. S, Ceram. Int., 35 (2009) 1103.

[18] Mano Priya. A, Kalai Selvan. R, Senthilkumar. B, Satheeshkumar. M. K,

Sanjeeviraja. C, Ceram. Int, 37, (2011), 2485.

[19] Miroslaw Maczka, Maciej Ptak, Michalina Kurnatowska, Leszek Kepinski, Pawel

Tomaszewski, Jerzy Hanuza, J. Solid State Chem, 184, (2011), 2446.

[20] Sagrario M. M, Antonio F. F, Ceram. Int, 30, (2004), 393.

[21] Parhi. P, Karthik. T. N, Manivannan V, J. Alloys Compd, 465, (2008), 380.

[22] Angana Sen, Panchanan Pramanik, J. Eur. Ceram. Soc, 21, (2001), 745.

[23] Rajagopal. S, Nataraj. D, Khyzhun. O. Yu, Yahia. D, Robichaud. J, Mangalaraj. D,

J. Alloys and Compd, 493, (2010), 340.

[24] Garcia Perez. U. M, Martinez-de la Cruz. A, Peral. J, Electrochim. Acta, 81,

(2012), 227.

[25] Tiziano Montini, Valentina Gombac, Abdul Hameed, Laura Felisari, Gianpiero

Adami, Paolo Fornasiero, Chem. Phys. Lett, 498, (2010), 113.

[26] Kisla. P. F. S, Anderson. D, J. Nanopart. Res, 13, (2011), 5927.

[27] Hongbo Fu, Chengsi Pan, Liwu Zhang, Yongfa Zhu, Mater.Res. Bull, 42, (2007),

696.

[28] Ingham. B, Chong. S. V, Tallon. J. L, Curr. Appl. Phys. 6, (2006), 553.

[29] Somchai. T, Surangkana. W, Titipun. T, Trans. Nonferrous Met. Soc. China, 19,

(2009), 100.

146

[30] Zhou. H, Yiu. Y, Aronson. M. C, Wong. S. S, J. Solid State Chem, 181, (2008),

1539.

[31] Cantalini. C, Wlodarski. W, Li. Y, Passacantando. M, Santucci. S, Comini. E,

Faglia. G, Sberveglieri. G, Sen Actuators B, 64, (2000), 182.

[32] Jian Zhang, Yan Zhang, Jing-Yi Yan, Shi-Kuo Li, Hai-Sheng Wang, Fang-Zhi

Huang, Yu-Hua Shen, An-Jian Xie, J. Nanopart. Res, 14, (2012), 796.

[33] Badilescu. S, Ashrit. P, Solid State Ion, 158, (2003), 187.

[34] Juliet Josephine Joy. J, Victor Jaya. N, J. Mater. Sci: Mater Electron, DOI

10.1007/s10854-012-1013-1.

[35] Lei. F, Yan. B, J. Am. Ceram. Soc. 92, (2009), 1262.

[36] Shi. F, Meng. J, Ren. Y, Su. Q, J. Phys. Chem. Solids, 59, (1998), 105.

[37] Zhang. Q, Yao. W. T, Chen. X, Zhu. L, Fu. Y, Zhang. G, Sheng. L, Yu. S. H,

Cryst. Growth Des. 7, (2007), 1423.

[38] Gang-qin. S, Jing-Kun. G, Ren. X. J, Dxing-Long, Lin. W. B, Run Zhang. Y, J.

Wuhan Univerisity of Technol. (Mater.Sci. Ed), 19, (2004), 1.

[39] Redfern. S. A. T, Phys. Rev. B, 48, (1993), 5761.

[40] Hanuza. J, Macalik. L, Maczka. M, Lutz. E. T. G, Vander Maas. J. H, J. Mol.

Struct, 511,(1999), 85.

[41] Hanuza. J, Maczka. M, Hermanowicz. K, Deren. P. J, Strek. W, Folcik. L, Drulis.

H, J. Solid State Chem, 148, (1999), 468.

[42] Hanuza. J, Maczka. M, Vander Mass. J. H, J. Solid State Chem, 117, (1995), 177.

[43] De Oliveira. A. L. M, Ferreira. J. M, Ma´rcia R. S. S, De Souza. S. C, Vieira.

F.T.G, Longo. E, Souza. A.G, Ieˆda M. G, J. Therm. Anal. Calorim, 97,

(2009), 167.

[44] Jia. R, Wu. Q, Zhang. G, Ding. Y, J. Mater. Sci. 42, (2007) 4887.

147

[45] Xie. H. D, Shen. D. Z, Wang. X. Q, Shen. G. Q, Cryst. Res. Technol, 42, (2007),

18.

[46] Bhaskar Kumar. G, Sivaiah. K, Buddhudu. S, Ceram. Int. 36, (2010), 199.

[47] Jeong H. R, Lim. C. S, Auh. K. H, Mater. Lett. 57, (2003), 1550.

[48] Gigorjeva. L, Millers. D, Grabis. J, Jankovica. D, Cent. Eur. J. Phys. 9, (2011),

510.

[49] Sofronov. D. S, Sofronova. E. M, Starikov. V. V, Voloshko. A. Y, Baymer. V. N,

Kudin. K. A, Matejchenko. P. V, Mamalis. A. G, Lavrynenko. S. N, J. Mater.

Eng. and Performance (2012), DOI: 10.1007/s11665-012-0200-9,105.

[50] Azad. A. M, Shyan. L. L. W, Pang. T. Y, Nee. C. H, Ceram. Inter. 26, (2000), 685.

[51] Aguas. M. D, Morris. L, Parkin. I. P, J. Mater. Sci. 37, (2002), 375.

[52] Shail Upadhyay, Om Parkash, J. Mater. Sci. Lett. 16, (1997), 1330.

[53] Koferstein. R, Jager. L, Zenkner. M, Ebbinghaus. S. G, J. Euro. Ceram. Soc. 29,

(2009), 2317.

[54] Guan Li, Litao. J, Shuqing. G, Yunfeng. L, Qinglin. G, Zhiping. Y, Fu

Guangsheng, J. Rare earths. 28, (2010), 292.

[55] Anjali. A. A, Bapit. M, J. Matastable and Nano Cryst. Mater. 23, (2005), 3.

[56] Aimable. A, Xin. B, Millot. N, Aymes. D, J. Solid State Chem. 181, (2008), 183.

[57] Borja- Urby. R, Diaz-Torres. L. A, Salas. P, Moctezuma. E, Vega. M, Angeles-

Chavez. C, Mater. Sci. Eng., B 176, (2011), 1382.

[58] Wensheng Lu, Schmidt. H, J. Sol-Gel. Sci. Techn, 42, (2007), 55.

[59] Gopal Reddy. C. V, Manorama. S .V, Rao. V. J, J. Mater. Sci: Mater. Electronic.

12, (2001) 137.

[60] Lu. W, Schmidt. H, Ceram. Int. 34,(2008), 645.

148

[61] Duran. P, Gutierrez. D, Tartaj. J, Baρares. M. A, Moure. C, J. Eur. Ceram. Soc.

22, (2002), 797.

[62] Wensheng Lu, Schmidt. H, J. Eur. Ceram. Soc. 25, (2005), 919.

[63] Nyquist. A. R, Kagel. R. O, ``Infrared Spectra of Inorganic Compounds'' Academic

Press, New York, (1971).

[64] Udawatte. Ch. P, Kakihana. M, Yoshimura. M, Solid State Ion. 108,(1998),23.

[65] Tao. S, Gao. F, Liu. X, Sorensen. O. T, Sens. Actuators B 71, (2000), 223.

[66] Cerda. J, Arbiol. J, Dezanneau. G, Diaz. R, Morante. J. R, Sensors and Actuators

B 84, (2002) 21.

[67] Bakar. S. N. A, Talib. I. A, Osman. N, Solid State Sci. and Technol. 17, (2009) 24.

[68] Boschini. F, Robertz. B., Rulmont. A, & Cloots. R, J. Euro. Ceram. Society 23,

(2003) 3035.

[69] Tunça. T, Uslub, Keskinc. S, J. Ceram. Process. Res. 12, (2011), 549.

[70] Nakayama. S, Sakamoto. A, Matsuki. K, Okimura. Y, Ohsumi. R, Nakayama. Y,

Sadaoka. Y, Chem. Lett, (1992), 2145.

[71] Ghosh. S, Dasgupta. S, Amarnath Sen, Sekhar. M. H, Mater. Res. Bull, 40, (2005),

2073.

[72] Chen. C, Cheng. J, Yu. S, Chen. L, Meng. Z, J. Cryst. Growth, 291, (2006),135.

[73] Lisnevskaya. L. V, Petrova. A. V, Inorg. Mater. 45, (2009), 930.

[74] Farhadi. S, Rashidi. N, J. Alloys and Compd. 503, (2010), 439.

[75] Khetre. S. M, Chopade. A. U, Khilare. C. J, Bamane. S. R, Int. J. Porous Mater. 1,

(2011), 1.

[76] Popa. M, Frantti. J, Kakihana. M, Solid State Ionics 135, (2002), 154.

[77] Zhange. H. M, Teraoka. Y, Yamazoe. N, Chem. Lett. 32, (1987), 665.

149

[78] Nakamoto. K, Infrared and Raman Spectra Of Inorganic and Coordination

Compounds, 4th ed., Wiley, New York, (1986), pp.252.

[79] Venkaiah. G, Venkateswara Rao. K, Sesha Sai Kumar. V, Shilpa. Ch. Ch., Int. J.

Mater. Methods and Technol. 1, (2013), 01.

[80] Sivakumar. M, Gedanken. A, Zhong. W, Jiang. Y. H, Du. Y. W, Brukental. I,

Bhattacharya. D, Yeshurun. Y, Nowik. I, J. Mater. Chem. 14, (2004), 764.

[81] Farhadi. S, Momeni. Z, Taherimehr. M, J. Alloys and Compd, 471, (2009), 5.

[82] He. Y, Wang. Y, Zhao. L, Wu. X, Wu. Y, J. Mol. Cat. A: Chemical, 337, (2011),

61.

[83] Yu. C, Yu. M, Li. C, Zhang. C, Yang. P, Lin. J, Cryst. Growth Des. 9, (2009), 783.

[84] Ke. D, Peng. T, Ma. L, Cai. P, Dai. K, Inorg. Chem. 48, (2009), 4685.

[85] Abdullah. A. H, Ali. N. M, Tahir. M. I. M, The Malaysian J. Anl. Sci. 13, (2009),

151.

[86] Zhang. A, Zhang. J. Mater. Sci.-Poland, 27, (2009), 1015.

Publications of the author based on the thesis work outlined above

1. Grinding-Assisted Solid-State Metathetic Synthesis of Divalent Transition Metal

Tungstates, U. Sujana Kumari*, P. Suresh and A. V. Prasada Rao, International

Research Journal of Pure & Applied Chemistry,3(1): 1-9, 2013.

2. Grinding Assisted Room Temperature Solid-State Metathetic Synthesis of Ca, Sr, Ba,

Pb and Cd Tungstates, U. Sujana Kumari*, P. Suresh and A. V. Prasada Rao,

International Journal of Applied Chemistry.ISSN 0973-1792 Volume 9, Number 1

(2013) pp. 51-58.

3. Solid-State Synthesis of LaFeO3 and BiFeO3 using K3[Fe(C2O4)3] and K3[Fe(CN)6]

as precursors with La/Bi Chloride, U. Sujana Kumari*, P. Suresh and A. V. Prasada

Rao, Int. J. Chem. Res., 2013v02i2 (15-20), ISSN: 2249-0329.

4. Solid-State Metathetic Synthesis of Phase Pure BaSnO3 and BaZrO3, International

Research Journal of Pure & Applied Chemistry, (under review).

5. Room Temperature Solid-State Synthesis of Visible Light Activated Photocatalysts

LaVO4 and BiVO4 (communicated).

___________________________________________________________________________________________

*Corresponding author: Email: [email protected];

International Research Journal of Pure &Applied Chemistry

3(1): 1-9, 2013

SCIENCEDOMAIN internationalwww.sciencedomain.org

Grinding-Assisted Solid-State MetatheticSynthesis of Divalent Transition Metal

Tungstates

U. Sujana Kumari1*, P. Suresh1 and A. V. Prasada Rao1

1Department of Inorganic and Analytical Chemistry, Andhra University, Visakhapatnam,530003, India.

Authors’ contributions

This work was carried out in collaboration with all authors. Author AVPR proposed the studyand supervised the work. Author USK performed the experimental work and analysis wrote

the first draft and author PS managed literature searches. All the authors read and approvedthe final manuscript.

Received 10th December 2012Accepted 1st January 2013

Published 8th February 2013

ABSTRACT

A convenient solid state metathetic synthesis has been developed for the preparation ofmetal tungstates MWO4 where M = Mn, Fe, Co, Ni and Zn using Na2WO4 andrespective MCl2 as reactants. Stoichiometric quantities of respective reactants weremixed and ground for 2hrs. XRD patterns of the homogenised mixture heat treated at400ºC for 4hrs and then washed free from NaCl bye product were in good agreementwith the respective JCPDS data showing the formation of phase pure compounds ineach case without any contamination. Microstructural investigation indicated particlesize of the order of µm.

Keywords: Solid state metathesis; manganese tungstate; iron tungstate; cobalt tungstate;nickel tungstate; zinc tungstate.

Research Article

International Research Journal of Pure & Applied Chemistry, 3(1): 1-9, 2013

2

1. INTRODUCTION

MWO4 type compounds where M is a divalent transition metal ion have attracted a lotscientific interest in recent times because of their many useful properties. These compoundsexist in two different crystal structures namely Scheelite and wolframite. Bivalent metal ionswith large ionic radius such as Ca2+, Sr2+, Ba2+ and Pb2+ prefer to form scheelite typestructures whereas metal ions with smaller ionic radius viz. Zn2+, Fe2+, Co2+, Ni2+ and Cd2+

tend to crystallize in wolframite type of structure. Crystal structure of Scheelite CaWO4 istetragonal with calcium surrounded by eight oxygens with isolated tetrahedra of WO4 beingnearly regular, where as in wolframite each W is coordinated to six oxygens unlike scheelite.MWO4 type divalent transition metal compounds have been reported to be useful forhumidity sensors [1], photocatalysts [2], photochromic [3] and as photoanodes [4].

3d transition metal tungstate powders have been synthesized by different techniques suchas solid-state reaction [5], chemical synthesis [6-10], hydrothermal [11-13], microwavehydrothermal [14], self propagation [15], template synthesis [16], combustion [17], moltensalt [18] and aqueous salt metathetic reaction [19]. Among these methods, solid-statereactions invariably involve higher temperatures of more than 800ºC while solution basedchemical methods require special equipment and subsequent annealing of amorphous ornano powders to temperatures above 500ºC for several hours to render them into crystallineform. Compared to these two basic approaches, solid-state metathesis (SSM) offers an easyand convenient route for the synthesis of many mixed metal oxides. These reactions involvedouble exchange with preferred formation of an alkali halide with large lattice energy whichfavours the reactions at lower temperatures compared to solid-state reactions betweenconstituent metal oxides. SSM has been successfully employed for the synthesis ofperovskite oxides [20], ordered double perovskites [21], LaAlO3 [22], Bi2WO6 [23] andmolybdates [24].

In continuation of our earlier work relating to room temperature solid-state metatheticsynthesis of Ca, Sr, Ba, Pb and Cd tungstates and synthesis of phase pure BaSnO3 andBaZrO3 we now report the solid-state metathetic synthesis of transition metal tungstatesMWO4 where M2+ = Fe, Mn, Co, Ni and Zn. Since the transition metal tungstates arepotential photocatalysts in the visible region [6] for the degradation of organic pollutants fromthe industrial exhausts, synthesis of these compounds at lower temperatures so as not toeffect the surface area of support is highly essential.

2. EXPERIMENTAL

2.1 Sample Preparation

Metal chlorides, MCl2 (where M=Fe, Mn, Co, Ni and Zn) along with Na2WO4 are used asprecursors. All the starting materials were analytical grade and were utilized as receivedwithout further purification. Stoichiometric quantities of the reactants were weighed and themixture was ground in an agate mortar for 2hrs with addition of ethanol as per the reactiongiven below.

MCl2.nH2O + Na2WO4→ MWO4 + 2NaCl + n.H2O

The homogenised mixture was dried in an air oven and subjected to heat treatment atdifferent temperatures. The resultant solid was washed with water until free from chloride


3

and the residue after drying was characterized for phase identification by X-ray diffraction(XRD).

2.2. Characterization Techniques

Phase purity of the final calcined powders was investigated with x-ray diffractometer(PANalytical- X’ Pert PRO, Japan) at room temperature, using Nickel filter Cu-Kα radiation(λ= 1.54059 Å), over a wide range of 10º ≤ 2θ ≤ 80º with a scanning speed of 2º min-1.Microstructural investigations of the samples were performed on the fractured surface of thesample using SEM (JEOL-JSM-6610LV, Tokyo, Japan). Energy Dispersive X-raySpectroscopy (EDS) was used to detect x-rays emitted from the sample duringbombardment with an electron beam to identify the elemental composition of the analyzedvolume. Raman spectra were recorded using SENTERRA from BRUKER Corporation.

3. RESULTS AND DISCUSSION

XRD patterns obtained for homogenised mixtures of MCl2+ Na2WO4 (where M= Fe, Mn, Co,Ni and Zn) subjected to heat treatment at 400ºC for 4hrs followed by washing with water untilfree from chloride and dried are given in Figures 1 to 4. XRD patterns of homogenisedmixture of NiCl2 + Na2WO4 at room temperature and heat treated at 300ºC and 400ºC for4hrs followed by washing are shown in Fig. 1. XRD patterns indicate formation of wellcrystalline NiWO4 only for the sample heat treated at 4000C for 4hrs. All the peaks in theXRD pattern could be indexed as the observed pattern is in good agreement with that ofNiWO4 given in JCPDS file no.15-0755. No extra peaks were noticed which indicates theformation of phase pure sample. Observed XRD patterns below 400ºC does not match withthe highest intensity peaks of NiCl2, Na2WO4 and NaCl. Hence these peaks may be ascribedto amorphous precursor with some partially crystalline NiWO4.((002), (022) and (220)peaks).

Fig. 1. XRD patterns of stoichiometric mixture of NiCl2 + Na2WO4 ground for 2hrs a)room temperature b) heat treated at 300ºC for 4hrs c) heat treated at 400ºC for 4hrs

and washed free of chloride.

Fig 2 shows the XRD patterns of homogenised mixture of stoichiometric amounts of ZnCl2and Na2WO4, ground for 2 hrs at room temperature and subjected to heat treatment of400ºC for 4hrs, both washed free of chloride and dried. The washed product of ZnWO4 at


4

room temperature did not indicate any sharp peaks characteristic of the reactants or NaClbye product. The broad peak coincides with the 100% intensity peak of ZnWO4 and this canbe attributed to ZnWO4 in the amorphous form. However, when subjected to heat treatmentat 400ºC, characteristic peaks due to formation of well crystalline phase pure ZnWO4 wereobtained and the data is in agreement with that reported in JCPDS file no.73-0554.

Fig. 2. XRD patterns of stiochiometric mixture of ZnCl2 + Na2WO4 ground for 2hrs a)room temperature, b) heat treated at 400ºC for 4hrs.

Fig 3 shows the XRD patterns obtained for mixtures of MnCl2+Na2WO4 and CoCl2+ Na2WO4ground for 2hrs and heated at 400ºC for 4hrs followed by washing to remove NaCl. Theobserved XRD patterns are in good agreement with the reported data for MnWO4 andCoWO4 of JCPDS files 80-0134 and 72-0479 respectively. Miroslaw Maczka et al [25]reported two different synthesis routes for MnWO4 (i) a hydrothermal method usingethanolamine and CTAB and (ii) by annealing a precursor obtained by co-precipitation. Intheir second method, XRD patterns were indicative of nanocrystalline MnWO4 formation withcrystallite size smaller than 20 and 26 nm when the synthesis was performed at 250 and400ºC, respectively. In the present method sharp peaks characteristic for large and well-crystallized MnWO4 particles were revealed for annealing at 400ºC for 4 hrs.

Fig. 3. XRD patterns of stoichiometric mixture of a) MnCl2 + Na2WO4 ground for 2hrsand heat treated at 400ºC for 4hrs washed and dried. b) CoCl2 + Na2WO4 ground for

2hrs, heat treated at 400º C at 4hrs washed and dried.


5

Fig 4 shows the XRD patterns obtained for mixture of FeCl2+Na2WO4 ground for 2hrs andheat treated at 400ºC for 2hrs and at 600ºC for 3hrs and washed free from NaCl byeproduct. Though the formation of FeWO4 is evident at 400ºC, for unambiguous indexing ofpeak positions, the sample is subjected to heat treatment at 600ºC for 3hrs to render it morecrystalline. All peaks for the resultant sample could be indexed in accordance with JCPDSfile no. 71-2391.

Synthesis of MWO4 powders was reported by solution based metathesis reaction usingequimolar solutions of metal nitrates and sodium tungstate, with subsequent heating of theprecipitate to 800ºC for 15hr [19]. Parhi et al [26] reported synthesis of ZnWO4, NiWO4 andMnWO4 by microwave assisted solid-state metathesis using 2.45 GHz microwave frequencyand a power of 1100 W for 10 minutes duration. Though crystalline ZnWO4 was obtained atroom temperature by this process, crystalline MnWO4 and NiWO4 were obtained only afterheat treatment at 500ºC for 6hrs. Angana sen etal [8] reported the synthesis of Co, Ni, Cuand Zn metal tungstates from the complete evaporation of polymer based metal-complexprecursor solution subjected to heat treatment. Rajagopal [27] reported the hydrothermalsynthesis of FeWO4 and CoWO4 using sodium tungstate with ferrous ammonium sulphateand cobalt chloride solutions as precursors respectively. Recently Garcia-Perez et al. [7]reported the synthesis of Co, Cu, Mn and Ni tungstates by co-precipitation method at 400ºC.Tiziano Montini etal reported the synthesis of transition metal tungstates MIIWO4 (M = CoII,NiII, CuII, ZnII) by reaction of transition metal nitrates with sodium tungstates and thensubjected to heat treatment at 500ºC. The SSM synthesis reported in the present study isthe lowest synthesis temperature reported for solid-state synthesis. It is less cumbersomeand could be performed at ambient pressure.

Fig. 4. XRD patterns of stoichiometric mixture of FeCl2 + Na2WO4 ground for 2hrs andheat treated at a) 400ºC for 4hrs b) 600ºC for 3hrs and washed free of chloride.

Fig 5 shows Raman spectra of MnWO4 , FeWO4, CoWO4, NiWO4 and ZnWO4 In terms ofgroup theoretical analysis, wolframite structure belonging to P2/c (z = 2) monoclinic structureis expected to give 18 (8Ag + 10 Bg) Raman-active bands out of 36 possible lattice modes[28]. Raman spectra for all samples revealed peaks due to 8Ag (breathing of tungstatetetrahedra) vibrations while some peaks due to 10Bg were not resolved. Based on theprevious reports, the most intense band in ZnWO4 was ascribed to antisymmetric bridgingmode associated with the tungsten chain [13]. In MnO4 the band at 127 cm-1 accompained


6

by two weak bands in the range 160 and 180 cm-1 were ascribed to interchain deformationand torsion modes [14]. Though extensive studies on Raman spectra of some of thesetungstates were reported in the literature subsequently [29], we at this stage did not make anelaborate interpretation of Raman spectra as our interest is limited to show the phaseformation of tungstates only. Our data is in agreement with those reported earlier[13],[14],[28].

Fig. 5. Raman spectra of MnWO4 , CoWO4, NiWO4 and ZnWO4 heat treated at 4000Cand FeWO4 heat treated at 6000C .

SEM micrograph of a representative sample FeWO4 powder heat treated at 6000C is shownin fig. 6 which shows particles of different sizes due to aggregation. Elemental analysis of thesample confirms the presence of Fe, W and O, with no extra lines due to any contamination.

Fig. 6. a) SEM image of FeWO4 powder and b) EDS of the FeWO4 powder under SEMinvestigation.

4. CONCLUSION

A simple low temperature solid state metathetic synthesis is reported for the preparation ofMWO4 (M = Fe, Mn, Co, Ni and Zn) powders using respective metal chlorides and sodiumtungstate as precursors. XRD patterns of respective powders obtained by mixing


7

stoichiometric quantities of the reactants, ground for two hours followed by heat treatment at400ºC for 4hrs, and washed free of chloride indicated formation of respective phase puremetal tungstates. Reaction temperatures reported for the synthesis of transition metaltungstates are less compared to these solid-state methods. The process is costeffective andsimple. Microstructural investigation indicated particle aggregation.

ACKNOWLEDGEMENTS

One of the authors (Sujana Kumari) gratefully acknowledges the research supervisor Prof.A. V. Prasada Rao for the constant encouragement throughout research work.

COMPETING INTERESTS

Authors have declared that no competing interests exist.

REFERENCES

1. Bhattacharya AK, Biswas RG, Hartridge A. Environment sensitive impedancespectroscopy and DC conductivity measurements on NiWO4. J. Mater. Sci.1997;32(2):353-356.

2. Huang G, Zhu Y. Synthesis and photocatalytic performance of ZnWO4 catalyst. MaterSci. Eng.B. 2007:139(2/3):201-208.

3. Kuzmin A, Purans J, Kalendarev R, Pailharey D, Mathey Y. XAS, XRD, AFM, andRaman studies of nickel tungstate electrochromic thin films. Electrochim. Acta2001;46:2233-2236.

4. Pandey PK, Bhave NS, Kharat RB. Structural, Optical, electrical and photovoltaicelectrochemical characterization of spray deposited NiWO4 thin films. Electrochim.Acta. 2006;51(22):4659-4664.

5. Bhaskar Kumar G, Sivaiah K, Buddhudu S. Synthesis and characterization of ZnWO4ceramic powder. Ceram. Inter. 2010; 36:199-202.

6. Tiziano Montini, Valentina Gombac, Abdul Hameed, Laura Felisari, Gianpiero Adami,Paolo Fornasiero. Synthesis, Characterization and photocatalytic performance oftransition metal tungstates. Chem. Phys. Lett. 2010;498:113-119.

7. Garcia Perez UM, Martinez-de la Cruz A, Peral J. Transition metal tungstatessynthesized by co-precipitation method: Basic photocatalytic properties. Electrochim.Acta. 2012;81:227-232.

8. Angana Sen, Panchanan Pramanik. A chemical synthetic route for the preparation offine-grained metal tungstate powder (M= Ca, Co, Ni, Cu, Zn). J. Eur. Ceram. Soc.2001;21:745-750.

9. Kalinko A, Kuzmin A. Raman and Photoluminesence spectroscopy of Zinctungstatepowders. J. Lumin. 2009;129:1144-1147.

10. Aleksandr Kalinko, Alexey Kotlov, Alexei Kuzmin, Vladimir Pankratov, Anatoli I. Popov,Liana Shirmana. Electronic excitations in ZnWO4 and ZnxNi1-xWO4 (x=0.1-0.9) usingVUV synchrotron radiation. Cent. Eur. J. Phys. 2011; 9(2):432-437.

11. Fu-Shan Wen, Xu Zhao, Hua Huo, Jie-Sheng Chen, E. Shu-Lin, Jia- Hua Zhang.Hydrothermal Synthesis and photoluminescent properties of ZnWO4 and Eu3+-dopedZnWO4. Mater. Lett. 2002;55:152-157.

12. Qiang Wang, Mingming Sun, Chunhong Li. Hydrothermal synthesis andphotoluminescent properties of zinc tungstate Nano/Micro structures. Adv. Mater. Res.2011;328-330:1580-1584.


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13. Hongbo Fu, Chengsi Pan, Liwu Zhang, Yongfa Zhu. Synthesis, Characterization andphotocatalytic properties of nanosized Bi2WO6, PbWO4 and ZnWO4 catalysts. Mater.Res. Bull. 2007;42:696-706.

14. Theo Kloprogge J, Matt L. Weier, Loc V. Duong, Roy L. Frost. Microwave-assistedsynthesis and characterisation of divalent metal tungstates nano crystalline minerals:ferberite, hubnerite, sanmartinite, scheelite and stolzite. Mater. Chem. and Phys.2004;88:438-443.

15. Tiaotiao Dong, Zhaohui Li, Zhengxin Ding, Ling Wu, Xuxu Wang, Xianzhi Fu.Characterizations and properties of Eu3+-doped ZnWO4 prepared via a facile self-propagating combustion method. Mater. Res. Bull.2008;43:1694-1701.

16. Hongjun Zhou, Yuen Yiu, Aronson MC, Stanislaus S. Wong. Ambient templatesynthesis of multiferroic MnWO4 nanowires and nanowires arrays. J. Solid StateChem. 2008;181:1539-1545.

17. Larisa Gigorjeva, Donats Millers, Janis Grabis, Dzidra Jankovica. Photoluminecenceand photocatalytic activity of zinc tungstate powders. Cent. Eur. J. Phys.2011;9(2):510-514.

18. Yakubovskaya AG, Katrunov KA, Tupitsyna IA, Starzhinskiy NG, Nagornaya LL,Zhukov AV, Zenya IM, Baumer VN, Vovk OM. Nanocrystalline Zinc and cadmiumtungstates: morphology, luminescent and scintillation properties. Funct. Mater.2011;18 (4):446-451.

19. Sagrario M. Montemayor, Antonio F. Fuentes. Electrochemical characteristics oflithium insertion in several 3D metal tungstates (MWO4, M= Mn, Co, Ni and Cu)prepared by aqueous reaction. Ceram. Int. 2004;30:393-400.

20. Radha Velchuri, Vijaya kumar B, Rama Devi V, Prasad G, Vithal M. Solid StateMetathesis of BaTiO3, PbTiO3, K0.5Bi0.5TiO3 and Na0.5Bi0.5TiO3. Ceram. Int. 2010;36:1485-1489.

21. Siva Kumar T, Lofland SE, Ramanujachary KV, Ramesha K, Subbanna GN,Gopalakrishnan J. Transforming n=1 members of the Ruddlesden-Popper phases to an=3 member through metathesis: synthesis of a layered perovskite, Ca2La2CuTi2O10.J. Solid State Chem. 2004;177:2635-2638.

22. Miroslaw Maczka, Esmeralda Mendoza-Mendoza, Antonio F Fuentes, Karol Lemanski,Przemyslaw Deren. Low-temperature synthesis, luminescence and phonon propertiesof Er and/or Dy doped LaAlO3 nanopowders. J. Solid State Chem. 2012;187:249-257.

23. Maczka M, Fuentes AF, Kepinski L, Diaz-Guillen MR, Hanuza J. Synthesis andelectrical, optical and phonon properties of nanosized Aurivillius phase Bi2WO6. Mater.Chem. and Phys. 2010;120:289-295.

24. Thangadurai V, Knittlmayer C, Weppner W. Metathetic room temperature preparationand characterization of scheelite-type ABO4 (A=Ca, Sr, Ba, Pb; B=Mo, W) powders.Mater. Sci. and Eng. B. 2004;106:228-233.

25. Miroslaw Maczka, Maciej Ptak, Michalina Kurnatowska, Leszek Kepinski, PawelTomaszewski, Jerzy Hanuza. Phonon properties of nanosized MnWO4 with differentsize and morphology. J. Solid State Chem. 2011;184:2446-2457.

26. Purnendu Parhi, Karthik TN, Manivannan V. Synthesis and characterization of metaltungstates by novel solid-state metathetic approach. J. Alloys and Compd.2008;465:380-386.

27. Rajagopal S, Nataraj D, Khyzhun O Yu, Yahia Djaoued, Robichaud J, Mangalaraj D.Hydrothermal synthesis and electronic properties of FeWO4 and CoWO4nanostructures. J. Alloys and Compd. 2010;493(1-2):340-345.

28. Kisla PF. Siqueira, Anderson Dias. Incipient crystallization of transition-metaltungstates under microwaves probed by Raman scattering and transmission electronmicroscopy. J. Nanopart. Res. 2011;13:5927-5933.


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29. Maczka M, Ptak M, Hermanowicz K, Majchrowski A, Pikul A, Hanuza J. Latticedynamics and temperature-dependent Raman and Infrared studies of multiferroicMn0.85Co0.15WO4 and Mn0.97Fe0.03WO4 crystals. Phys. Rev. B. 2011;83:174439.

_________________________________________________________________________© 2013 Kumari et al.; This is an Open Access article distributed under the terms of the Creative CommonsAttribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, andreproduction in any medium, provided the original work is properly cited.

Peer-review history:The peer review history for this paper can be accessed here:

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International Journal of Applied Chemistry. ISSN 0973-1792 Volume 9, Number 1 (2013) pp. 51-58 © Research India Publications http://www.ripublication.com/ijac.htm

Grinding Assisted Room Temperature Solid-State Metathetic Synthesis of Ca, Sr, Ba, Pb and Cd

Tungstates

U. Sujana Kumari*, P. Suresh and A. V. Prasada Rao

Department of Inorganic and Analytical chemistry,

A.U College of science and technology, Andhra University, Vishakapatnam-530003, India.

E-mail:*[email protected]

ABSTRACT A facile room temperature solid state metathetic synthesis has been developed for the preparation of some metal tungstates, MWO4 where M= Ca, Sr, Ba, Pb and Cd using Na2WO4 and respective MCl2 as reactants. Stoichiometric quantities of respective reactants were mixed and ground in an agate mortar for half an hour. The grinding induced solid state metathetic reaction between the reactants and the reaction proceeded to completion. The resultant mixtures washed with distilled water to remove NaCl bye product showed XRD patterns characteristic of respective MWO4 which are in good agreement with the corresponding JCPDS data. Microstructural investigation indicated particle size of the order of µm. Keywords: Solid-state metathesis, Calcium tungstate, Strontium tungstate, Barium tungstate, Lead tungstate, Cadmium tungstate.

Introduction Functional mixed metal oxides have been found to be extremely useful for a large number of applications in solid-state devices. These oxides are synthesized by several techniques such as solid-state method, chemical methods of precipitation, sol-gel, pechini polymerisation, self propagation, spray pyrolysis, hydrothermal, chemie douche etc Among the above, limited by diffusion distances solid state methods require high temperatures compared to solution routes in which mixing of reactants occur at molecular level. Nevetheless, in some chemical methods like sol-gel, use of metal alkoxide precursors preclude the adoption of this method for powder synthesis

52 U. Sujana Kumari, P. Suresh & A. V. Prasada Rao

since it is not cost effective. Alternatively, solid-state metathesis synthesis, provides a convenient route for the synthesis of several mixed metal oxides [1-4]. The authors recently reported synthesis of transition metal tungstates by solid-state metathesis [5]. These reactions are self-propagating and are favoured by the formation of stable bye product of an alkali halide with high lattice energy that acts as driving force for the metathetic reaction to proceed. Scheelite is the mineral name for calcium tungstate, CaWO4. The crystal structure of scheelite is tetragonal consisting of calcium surrounded by eight oxygens with the isolated tetrahedra of WO4 being nearly regular with four equal W-O distances [6]. MWO4 type oxides with scheelite structure where M=Ca, Sr, Ba, Pb and Cd have been reported to be useful for laser host materials [7], scintillators [8], oxide ion conductors [9,10] and as humidity sensors [11]. Synthesis of MWO4 powders is reported by solid-state method [12], co-precipitation [13], solvothermal process [14], Sol-gel [15], reverse micellar reactions [16], microwave hydrothermal [17], combustion [18] and hydrothermal [19]. Thangadurai etal [20] reported the synthesis of ABO4 (A=Ca, Sr, Ba, Pb; B=Mo,W) powders by solution based metathetic approach. Parhi etal [21] reported synthesis of metal tungstates using solid-state metathetic approach assisted by microwave energy. In the present paper, we report a facile room temperature solid-state metathetic synthesis of scheelite type MWO4 (M=Ca,Sr,Ba,Pb) and wulframite type CdWO4 powders. Experimental Sample preparation A.R grade sodium tungstate, Na2WO4 and corresponding metal chlorides MCl2 (where M = Ca, Sr, Ba, Pb and Cd) were used as starting materials. Stoichiometric amounts of MCl2 and Na2WO4 as per the following reaction MCl2+Na2WO4→ MWO4+2NaCl were weighed and ground thoroughly for 30 minutes in an agate mortar. The homogenized mixture was washed with distilled water to remove NaCl bye product and dried at 1000 C in an air oven. Phase identification of the products was performed by XRD. Characterization Techniques Phase purity of the final calcined powders was investigated with x-ray diffractometer (PANalytical- X’ Pert PRO, Japan) at room temperature, using Nickel filter Cu-Kα radiation (λ= 1.54059 Å), over a range of 10º ≤ 2θ ≤ 80º with a scan rate of 2º min-1. Microstructural investigation of the samples was performed on the dried powdered sample using SEM (JEOL-JSM-6610LV, Tokyo, Japan). Energy Dispersive X-ray Spectroscopy (EDS) was used to detect x-rays emitted from the sample during bombardment with an electron beam to identify the elemental composition of the analyzed volume. Raman spectra were recorded using SENTERRA from BRUKER Corporation.

Grinding Assisted Room Temperature Solid-State Metathetic Synthesis 53

Results and Discussion Metal tungstates with large bivalent cations like Ca2+, Sr2+, Ba2+ and Pb2+ tend to crystallize in Scheelite type tetragonal structure where as metal ions with smaller cation radii such as Zn2+, Fe2+, Co2+ , Ni2+ and Cd2+crystallize in Wolframite type structure. In the former, each W is surrounded by four oxygen atoms while in the latter each W is surrounded by six oxygen atoms giving rise to a distorted octahedral coordination [6]. Fig.1 shows XRD patterns of unground mixture of stoichiometric amounts of MCl2 (M=Ba, Ca, Sr and Pb) and Na2WO4, and mixture after grinding for half an hour in an agate mortar at room temperature followed by washing with water. XRD pattern shown in Fig.1(i)(a) for the unground mixture of BaCl2+Na2WO4 shows peaks characteristic of the reactants BaCl2 and Na2WO4, while all the peaks in XRD pattern depicted in Fig.1(i)(b) for the same mixture after grinding and washing could be indexed as due to BaWO4 of JCPDS card Number (43- 0646) with no extra peaks due to NaCl or reactants as impurity suggesting that metathetic reaction is induced by grinding the reactants together. Recently, Chang Sung Lim [22] reported formation of BaWO4 using a solid state metathetic route assisted by cyclic microwave irradiation with subsequent heat treatment at 600oC for 3hrs. Cavalcante [23] also reported formation of BaWO4 powders by co-precipitation and microwave processing at 413K. The room temperature solid state metathetic synthesis reported in the present study is the lowest temperature so far reported for the synthesis of BaWO4 powders.

Fig. 1 (i) XRD patterns of a) physical mixture of BaCl2+Na2WO4 b) stoichometric

mixture of BaCl2+Na2WO4 ground and washed with water. (ii) XRD Patterns of MCl2 + Na2WO4 ground for 30 minutes and washed with water,

M is a) Ca b) Sr and c) Pb. Fig.1(ii) depicts XRD patterns of resultant powders obtained from respective stoichiometric mixtures of MCl2 (M=Ca, Sr and Pb) and Na2WO4 ground at room

54 U. Sujana Kumari, P. Suresh & A. V. Prasada Rao temperature for half an hour followed by washing with distilled water. These XRD patterns agree well with the respective JCPDS data for CaWO4, SrWO4 and PbWO4 and showed no extra peaks indicating that samples are phase pure. Unit Cell parameters calculated using TJB Holland & SAT Redfern 1995 software from XRD data of these samples are given in Table.1. Zalga [24] reported synthesis of calcium and barium tungstates by aqueous sol-gel method using tartaric acid as complexing agent and heating the xerogel obtained at 5000C for 1hr with subsequent annealing at 8000C for 1hr. Sulawan KaowPhong et al [25] reported formation of nanostructured CaWO4 by solvothermal synthesis at a temperature of 1600C for 6h, using Ca(NO3)24H2O and Na2WO4.2H2O as precursors. Xiufeng Zhao [26] developed a procedure for SrWO4 via a precipitation reaction between SrCl2 and Na2WO4 in presence of polymethacrylic acid. The procedure reported in the present paper for the synthesis of Ca, Sr, Ba, Pb and Cd tungstates is simple, cost effective, operational at ambient temperature and requires no further annealing as required for samples prepared by using microwave energy or hydrothermal bombs.

Table 1 Calculated Lattice parameters of Ca, Sr, Ba, Pb tungstates

Compound Lattice Parameters calculated in (A0) Lattice Parameters from JCPDS in (A0) a c a c CaWO4 5.21540 11.31500 5.2425 11.371 SrWO4 5.43764 11.99367 5.4168 11.951 BaWO4 5.58568 12.65862 5.6123 12.7059 PbWO4 5.44111 12.02770 5.4403 12.0495

Fig.2 depicts XRD patterns of ground mixture obtained from stoichiometric quantities

of CdCl2 and Na2WO4 followed by washing with distilled water and drying in an air oven. Though all the XRD peaks in fig 2(a) are indicative of the formation of CdWO4 at room temperature, since the peaks are broad indicating nano range sample particles, it is subjected to heat treatment at 6000C for 3hrs to improve crystallization and obtain sharper peaks that could be indexed unambiguously. XRD pattern of the heat treated sample shown in Fig. 2(b) agreed well with that of CdWO4 (JCPDS card Number 14-0676). The indexing confirmed that CdWO4 was formed at room temperature.


Fig. 2 XRD Patterns of stoichiometric mixture of CdCl2 and Na2WO4 ground at room temperature followed by washing with distilled water a) powder after drying in an air oven b) powder heat treated at 6000C for 3hrs. Formation of CaWO4, SrWO4, BaWO4, PbWO4 was further studied by Raman spectroscopy and the obtained spectra given in Fig 3(i) are in good agreement with the literature data [17]. Fig 3(ii) shows the Raman spectra of CdWO4 at room temperature. The well resolved peaks obtained in this study agree well with the internal Raman modes, free rotation modes and external modes reported by Chang Sung Lim [27]. Chang Sung Lim [27] synthesized well crystalline monoclinic wolframite type CdWO4 using cyclic microwave irradiation followed by subsequent heat treatment at 6000C for 3hrs. Recently Sofronor et al [28] reported microwave synthesis of CdWO4 using Cd(NO3)2 and ammonium tungstates as precursors. According to these investigators CdWO4 Scheelite phase exists upto 2000C and thereafter transforms to monoclinic structure.

Fig. 3 (i) Raman Spectra of (a) CaWO4 (b) SrWO4 (c) BaWO4 (d) PbWO4 at room temperature (ii) Raman spectra of CdWO4.


Fig.4 shows SEM micrographs of BaWO4 and CdWO4 powders. As can be seen from the SEM micrographs, BaWO4 showed no characteristic morphology where as CdWO4 showed a typical morphology with formation of anisotropic particles. From the SEM image, the particle size is estimated to be in the range of micrometer.

Fig. 4 SEM image of a) BaWO4 powder and b) CdWO4 powder heat treated at 6000 C for 3 hrs.

The above results clearly demonstrate that the solid-state metathetic synthesis route yields phase pure BaWO4, CaWO4, SrWO4, PbWO4 and CdWO4 at room temperature without making use of oxide precursors and without subjecting the reaction mixture to microwave energy or thermal energy. Conclusions A simple room temperature solid state metathetic synthesis is reported for the preparation of MWO4 (M=Ca, Sr, Ba, Pb and Cd) using respective metal chlorides and sodium tungstate as reactants. XRD patterns of dried powders obtained by mixing stoichiometric quantities of the respective reactants, ground for half an hour with subsequent removal of bye product NaCl by washing indicated formation of phase pure tungstates of Ca, Sr, Ba and Pb with scheelite structure and CdWO4 of wulframite structure. From the microstructural investigation it is clear that CdWO4 exibited a different morphology of anisotropic particles where as BaWO4 showed particles with no characteristic morphology. Particle size was estimated to be of the order of µm in both cases. References

[1] Tapas Kumar, M., and Gopalakrishnan, J., 2005, “New Route to Ordered Double Perovskites: Synthesis of Rock Salt Oxides, Li4MWO6, and their Transformation to Sr2MWO6 (M=Mg, Mn, Fe, Ni) via Metathesis,” Chem. Mater., 17(9), pp. 2310-2316.


[2] Tapas Kumar, M., and Gopalakrishnan, J., 2004, “From Rock Salt to Perovskites: a Metathesis Route for the Synthesis of Perovskite Oxides of Current Interest,” J. Mater. Chem., 14, pp. 1273-1280.

[3] Monalisha, P., Ram, S., and Gopala Krishnan, J., 2003, “Preparation of PbZrO3/ASO4 Composites (A= Ca, Sr, Ba) and PbZrO3 by Metathetic Reactions in the Solid State: Metathetic Exchange of Divalent Species,” Chem. Mater., 15(7), pp. 1554-1559.

[4] Radha, V., Vijaya kumar, B., Rama Devi, V., Prasad, G., and Vithal, M., 2010, “Solid State Metathesis of BaTiO3, PbTiO3, K0.5Bi0.5TiO3 and Na0.5Bi0.5TiO3,” J. Ceram. Int., 36(4), pp. 1485-1489.

[5] Sujana Kumari. U., Suresh. P., Prasada Rao. A.V., “Grinding Assisted Solid-State Metathesis of Divalent Transition Metal Tungstates”, Int. Res. J. Pure and Appl. Chem., (in press).

[6] Muller, O., and Roy, R., 1974, The Major Ternary Structural Families, Springer-Verlag, New York.

[7] Chen, W., Inagawa, Y., Omatsu, T., Tateda, M., Takeuchi, N., and Usuki, Y., 2001, “Diode-Pumped, Self-Stimulating, Passively Q-Switched Nd3+: PbWO4 Raman Laser,” Opt. Commun., 194(4-6), pp. 401-407.

[8] Takai, S., Sugiura, K., and Esaka, T., 1999, “Ionic Conduction Properties, Pb1-xMxWO4+δ (M=Pr, Tb),” Mater. Res. Bull., 34, pp. 193-202.

[9] Nagirnyi, V., Feldbach, E., Onsson, L. J., Kirm. M., Lushchik, A., Lushchik, Ch., Nagornaya, LL., Ryzhikov, VD., Savikhiu, F., Svensson, G., and Tupitsina, IA., 1998, “Excitonic and Recombination Processes in CaWO4 and CdWO4 Scintillators under Synchrotron Irradiation,” Radiat. Meas., 29, pp. 247 – 250.

[10] Esaka, T., 2000, “Ionic Conduction in Substituted Scheelite-type Oxides,” Solid. State. Ion., 136-137, pp. 1-9.

[11] Guoxin, Z., Sefei, Y., Zheng, Li., Lan, Z., Wei, Z., Haiying, Z., Hua, S., Yongxian, W., 2010, “Synthesis and Photoluminescence Properties of Aqueous CdWO4 Quantum Dots with WO6

6- Luminescence Center,” Appl. Surf. Sci., 257(1), pp. 302–305.

[12] Blasse, G., and Brixner, L. H., 1990, “UltraViolet Emission from ABO4 - type Niobates, Tantalates and Tungstates,” Chem. Phys. Lett., 173(5-6), pp. 409-411.

[13] Paski, EF., and Blades, MW., 1988, “Analysis of Inorganic Powders by Time-Wavelength Resolved Luminescence Spectroscopy,” Anal. Chem., 60(11), pp. 1224-1230.

[14] Shu-Jian, C., Jing, L., Xue-Tai, C., Jian-Ming, H., Ziling, X., Xiao-Zeng, Y., 2003, “Solvothermal Synthesis and Characterization of Crystalline CaWO4 Nanoparticles,” J. Cryst. Growth., 253(1-4), pp. 361–365.

[15] Mackenzie, JD., and Bescher, E P., 2007, “Chemical Routes in the Synthesis of Nanomaterials using the Sol-Gel Process,” Acc. Chem. Res., 40(9), pp. 810-8.

[16] Kwan, S., Kim, F., Akana, J., and Yang, P., 2001, “Synthesis and Assembly of BaWO4 Nanorods,” Chem. Commun., (5), pp. 447-448.


[17] Kisla, P.F.S., Roberto, L. M., Marcelo, V., and Anderson, D., 2010, “Microwave-Hydrothermal Preparation of Alkaline-Earth-Metal Tungstates,” J. Mater. Sci., 45(22), pp. 6083-6093.

[18] Ryu, JM., Yoon, JW., Lim, CS., and Shim, KB., 2006, “Microwave-Assisted Synthesis of MWO4 and MMO4 [M= Ca, Ni] Nanopowders using Citrate Complex Precursor,” Key. Eng. Mater., 317, pp. 223-226.

[19] Yiguo, Su., Liping, Li., Guangshe, Li., 2008, “Synthesis and Optium Luminescence of CaWO4 – Based Red Phosphors with Codoping of Eu3+ and Na+,” Chem. Mater., 20(19), pp. 6060-6067.

[20] Thangadurai, V., Knittlmayer, C., and Weppner, W., 2004, “Metathetic Room Temperature Preparation and Characterization of Scheelite-type ABO4 (A=Ca, Sr, Ba, Pb; B= Mo, W) Powders,” Mater. Sci. and Eng B., 106, pp. 228-233.

[21] Parhi, P., Karthik, TN., Manivannan, V., 2008, “Synthesis and Characterization of Metal Tungstates by Novel Solid-State Metathetic Approach,” J. Alloys and Compd., 465, pp. 380-386.

[22] Chang Sung, L., 2011, “Solid-State Metathetic Synthesis of BaMO4 (M=W,Mo) Assisted by Microwave Irradiation,” J. Ceram. Process. Res., 12(5), pp. 544-548.

[23] Cavalcante, LS., Sczancoski, JC., Lima, LF., Espinosa Jr, JWM., Pizani, PS., Varela, JA., and Longo, E., 2009, “Synthesis Characterization Anisotropic Growth and Photoluminescence of BaWO4,” Cryst. Growth. Des. 9(2), pp. 1002-1012.

[24] Zalga, A., Moravec, Z., Pinkas, J., Kareiva, A., 2011, “On the Sol -Gel Preparation of Different Tungstates and Molybdates,” J. Therm. Anal. Calorim., 105, pp. 3 -11.

[25] Sulawan, K., Titipun, T., and Somchai, T., 2010, “Effect of Solvents on the Microstructure of CaWO4 Prepared by a Solvothermal Synthesis,” J. Ceram. Process. Res., 11(4), pp. 432-436.

[26] Xiufeng, Z., Teresa, L. Y. C., Xitian, Z., Dickon, H.L.Ng., Jiaguo, Yu., 2006, “Facile Preparation of Strontium Tungstate and Tungsten Trioxide Hollow Spheres,” J. Am. Ceram. Soc., 89(9), pp. 2960-2963.

[27] Chang Sung, L., Kyoung Hun, K., and Kwang Bo, Shim., 2011, “Cyclic Microwave Synthesis and Characterization of Cadmium Tungstate Particles Assisted by a Solid-State Metathetic Reaction,” J. Ceram. Process. Res., 12(6), pp. 727-731.

[28] Sofronov, DS., Sofronova, EM., Starikov, VV., Baymer, VN., Kudin, KA., Matejchenko, PV., Mamalis, AG., Lavrynenko, SN., 2012, “Microwave Synthesis of Tetragonal Phase CdWO4,” Mater. Manuf. Processes., 27(5), pp. 490-493.

SOLID-STATE SYNTHESIS OF LaFeO3 AND BiFeO3 USING

K3[Fe(C2O4)3] AND K3[Fe(CN)6] AS PRECURSORS WITH

La/Bi CHLORIDE U. Sujana Kumari

a*, P. Suresh

a, A. V. Prasada Rao

a

aDepartment of Inorganic and Analytical Chemistry, Andhra University,

Visakhapatnam, 530003, India. *

Corresponding author. Tel.:+91-9490149128, +91-9989991268

E-mail address: [email protected] (U. Sujana Kumari).

Postal Address: U. Sujana Kumari, Department of Inorganic and Analytical chemistry,

A.U College of science and technology, Andhra University, Vishakapatnam,

530003, India

Abstract

Phase pure LaFeO3 and BiFeO3 were synthesized from the precursors K3[Fe(C2O4)3] and respective metal

chlorides LaCl3 and BiCl3. The reaction temperatures for the above are some what lower than those reported in

literature for traditional solid-state synthesis making use of oxides and or carbonates as precursors. Phase

identification and microstructure were done by X-ray diffractometry and Scanning electron microscopy.

Submicrometer agglomerated particles were observed in the microstructural investigation.

Keywords: Bismuth ferrate, Lanathanum ferrate, potassium tris(oxalato) ferrate, potassium ferricyanide

INTRODUCTION

Lanthanum ferrate, LaFeO3 is a p-type

semiconductor with a distorted perovskite

type crystal structure of Pbnm symmetry

and exhibits an unusual variety of

magnetic properties and structural

changes. Being chemically stable in

reducing as well as oxidising atmosphere,

LaFeO3 is useful for several applications

relating to sensing properties of toxic and

noxious gases NOx and CO [1], catalytic

activity for oxidation of organic pollutants

in ambient conditions [2], diesel soot

oxidation [3], solid oxide fuel cells [4],

magneto hydrodynamic power generation

[5] and bio sensing in dendritic form for

highlyselective and sensitive determination

of neuro transmitted compounds of

dopamine [6],etc. Several synthesis

methods for LaFeO3 in terms of solid-state

[7], hydrothermal [8], sol-gel [9], wet

chemical [10], sonochemical [11],

combustion [12-15], thermal

decomposition of precursor [16], hotsoap

method [17] have been reported in

literature.

Bismuth ferrate, BiFeO3 is a multiferroic

that exhibits both ferroelectric and

antiferromagnetic ordering with a curie

temperature Tc=1083K and Neel

temperature TN=657K respectively. The

magneto-electric coupling in a multiferroic

generates a unique magneto electric effect

which allows the polarisation to be tuned

under external magnetic field or

magnetization to be tuned under external

electric field. Consequently BiFeO3 finds

use for several applications such as non

volatile information storage, spintronic

sensors, wireless sensors, digital

memories, spin filters etc. BiFeO3

crystalyses in a rhombohedrally distorted

perovskite structure of R3C symmetry in

which all metal ions are displaced along

the (111) direction relative to the ideal

centrosymmetric position and the oxygen

octahedra surrounding Fe are rotated

alternatively around the axis. The

antiferromagnetic ordering remains upto

Neel temperature. Synthesis of BiFeO3 has

been reported by several methods that

include solid-state [18], wet chemical [19-

21], hydrothermal [22-26], mechano

chemical [27], solution combustion [28-

29], microwave hydrothermal [30] and sol-

gel [31].

Of the various methods that are reported in

literature for the synthesis of mixed

bimetallic oxides of La/Bi and Fe,

conventional solid-state reactions between

corresponding oxides and/or carbonate

U. Sujana Kumari, P. Suresh, A.V. Prasada Rao, Int. J. Chem. Res., 2013v02i2 (15-20) ISSN: 2249-0329

IJCSR | MAR - APR 2013 Available [email protected]

15

precursors require high reaction

temperatures of the order of 12000C with

intermitant grinding steps to ensure

homogeneity. Wet chemical methods also

require high calcination temperatures for

evolution of the required phase with good

crystal structure. Sol-gel process though

attractive, is not cost effective and is less

suitable for large scale applications. In

view of the technological importance of

LaFeO3 and BiFeO3 as outlined above,

development and cost effective new

synthesis methods are always under

investigation.

In this paper, we report the synthesis

method for phase pure BiFeO3 and LaFeO3

making use of non-oxide precursors MCl3

(M=La, Bi).

EXPERIMENTAL

A.R.grade LaCl3.7H2O and BiCl3 were

used as precursors along with

K3[Fe(C2O4)3].3H2O. Stoichiometric

quantities of reactants in the 1:1 molar

ratio were weighed and ground thoroughly

in an agate mortar for 4hrs in presence of

ethanol. The resultant homogenised

mixture was dried in an air oven and

subjected to heat treatment at 6000C and

8000C for 8 hours and 4 hours

respectively. Phase identification was done

by X-ray diffractometer (panalytical “X”

Pert pro) using CuKα radiation.

Microstructural investigation was done by

Scanning Electron Microscope (JEOL

JSM 6610 LV). Thermo gravimetric

analysis was done using TG/DTA, TA

Instruments SDT Q600 from anbient

temperature to 9000C with a heating rate of

100 C min

-1.

RESULTS AND DISCUSSION

We have succeeded in preparing tungsates

of Ca, Sr, Ba, Pb and Cd at room

temperature [32] and those of transition

metal ions at 4000C by solid-state

metathesis [33]. As an extension of this

work the synthesis of LaFeO3 and BiFeO3

was undertaken presuming feasibility of

metathesis between the MCl3 (M= La, Bi)

and K3[Fe(C2O4)3]. 3H2O precursors.

However, contrary to the expectation

decomposition preceeded metathesis

reaction in this case as evidenced by

thermoanalytical study.

Thermogram of the homogenised mixture

of LaCl3 and K3[Fe(C2O4)3] in 1:1 mole

ratio is shown in Fig.1 which showed a

continuous weight loss upto 8500C and the

total weight loss, upto 8500C corresponds

to 57%. The experimentally observed

weight loss can be ascribed to the

following reactions, occurring either in

succession or simultaneously in the

temperature range of 500 to 850

0C.

LaCl3. 7H2O → LaCl3 + 7H2O

K3[Fe(C2O4)3]. 3 H2O → K3[Fe(C2O4)3] +

3 H2O

2K3[Fe(C2O4)3] → 3K2O + Fe2O3

+6CO2+6CO

allowing the overall reaction after

decomposition to facilitate the formation

of LaFeO3 as per the following equation.

LaCl3. 7H2O + K3[Fe(C2O4)3]. 3 H2O →

LaFeO3 + 10 H2O + 3CO2 + 3CO + 3KCl

for which the theoretical weight loss is

55%. Since the observed weight loss of

57% agrees with the theoretical weight

loss, the product expected above 8500C

must be LaFeO3.

200 400 600 800 1000

40

50

60

70

80

90

100

110

Temperature 0C

We

igh

t %

Fig. 1 Thermogram of homogenised

mixture of LaCl3 and K3[Fe(C2O4)3] in the



16

1:1 mole ratio from room temperature to

9500C.

Inorder to confirm the formation of

LaFeO3, the original well ground mixture

of LaCl3 and K3[Fe(C2O4)3] is subjected to

heat treatment at 6000C and 1000

0C for 8

hrs and 2 hrs respectively. X-ray

diffraction patterns obtained for the heat

treated samples washed with water to

remove expected byproduct KCl are

shown in Fig. 2. XRD pattern in fig 2(a)

did not show the formation of LaFeO3

where as in the XRD pattern shown in fig

2(b), all the observed peaks could be

indexed due to LaFeO3 of JCPDS card no.

37-1493. Since all the observed diffraction

peaks are in good agreement with that of

LaFeO3 and since there are no extra peaks

either due to contamination or due to

unreacted precursors, the formation of

phase pure LaFeO3 is confirmed.

Synthesis of LaFeO3 has also been

reported in literature from the hetronuclear

bimetallic complex precursor

La[Fe(CN)6].5H2O prepared from mixing

the aqueous solutions of La(NO3)3,

K3[Fe(CN)6] and thermal decomposition

of the complex precursor yielded LaFeO3

at 6200C [34]. The fact that stoichiometric

solid-state mixture of LaCl3 and

K3[Fe(C2O4)3] on heating yielded LaFeO3

at elevated tempertatures coupled with the

literature report of the thermal

decomposition of La[Fe(CN)6] we thought

whether a solid-state stoichiometric

mixture of LaCl3 and K3[Fe(CN)6] will

also yield LaFeO3, following solid-state

metathesis reaction pathway. Conforming

to our expectation, the solid mixture of

LaCl3 and K3[Fe(CN)6] in 1:1 mole ratio

when heat treated at 6000C for 4 hrs

followed by washing with water to remove

KCl byeproduct yielded LaFeO3 as

observed from XRD shown in fig 2(c)

which is well in agreement with that of

LaFeO3 of JCPDS card no 37-1493. The

net result indicates that formation of phase

pure LaFeO3 could be achieved even from

physical mixture of precursors which

avoids preparation of complex precursor

La[Fe(CN)6].5H2O from the aqueous

solutions of the reactants.

Fig. 2 XRD patterns of 1:1 ground

mixtures of LaCl3 and K3[Fe(C2O4)3] heat

treated at (a) 6000C for 8hrs (b) 1000

0C for

2 hrs and (c) mixture of LaCl3 and

K3[Fe(CN)6] heat treated at 6000C for

2hrs.

Fig. 3 depicts the XRD pattern obtained

for the stoichiometric well-ground mixture

of BiCl3 and K3[Fe(C2O4)3] in the mole

ratio of 1:1, heat treated at 6000C for 8 hrs

and 8000C for 4 hrs followed by washing

with water. XRD pattern shown in fig 3(a)

did not indicate the formation of BiFeO3

since the diffraction peaks observed at

2 = 28, 52, and 670 are corresponding to

the reactants. Where as, all the peaks in the

XRD pattern in fig.3 (b) could be indexed

to BiFeO3 (JCPDS Card no. 86-1518). The

absence of any extra peaks either due to

contamination or due to unreacted

precursors confirm the formation of phase

pure BiFeO3. Formation of BiFeO3 has

also been reported in literature from the

thermal decomposition of the bimetallic

complex precursor Bi[Fe(CN)6] at 600-



17

6500C between 5 and 10 hrs. As in the

case of LaFeO3, formation of BiFeO3 from

the heat treatment of a physical mixture of

BiCl3 and K3[Fe(CN)6] is also

investigated, but unlike LaFeO3, there is

no evidence of formation of BiFeO3 even

upto 8000C.

Fig. 3 XRD patterns of 1:1 ground mixtures of BiCl3 and K3[Fe(C2O4)3] heat treated at (a)

6000C for 8hrs (b) 800

0C for 4hrs.

The SEM micrographs at LaFeO3 and

BiFeO3 powders obtained at 10000C and

6000C respectively from K3[Fe(C2O4)3]

and respective metal chlorides are shown

in Fig.4. SEM micrographs, indicate

submicrometer aggregated particles of no

characteristic shape.

Fig. 4 SEM micrographs of (a) LaFeO3 obtained at 10000C from LaCl3 and K3[Fe(C2O4)3] (b)

BiFeO3 obtained at 8000C from BiCl3 and K3[Fe(C2O4)3].



18

CONCLUSIONS From the above observations, it can be

concluded that phase pure LaFeO3 and

BiFeO3 could be obtained by heat

treatment of solid mixtures of MCl3

(M=La, Bi) and K3[Fe(C2O4)3] at different

temperatures. Further LaFeO3 could also

be obtained from the heat treatment of

LaCl3 and K3[Fe(CN)6] solid mixture of

1:1 mole ratio at 6000C where as BiFeO3

was not formed from the heat treatment of

the stoichiometric mixture of BiCl3 and

K3[Fe(CN)6] even upto 8000C. Synthesis

procedure reported in the present paper

yielded LaFeO3 and BiFeO3 at

considerably lower temperatures compared

to corresponding solid-state syntheses

making use of pure oxide precursors of

La2O3/Bi2O3 and Fe2O3.

REFERENCES

1. BAI ShouLi, SHI Bingjie, MA Lijing,

YANG PengCheng, Liu ZhiYong, Li

DianQing, CHEN Aifan, Sci China

Chem, 2009; 52; 2106-2113.

2. Faye J, Guelou E, Barrault J, Tatibouet

JM, Valange S, Top Catal,

2009;52;1211-1219.

3. Keita Taniguchi, Takahiro Hirano,

Tsuyoshi Tosho, Tomohiro Akiyama,

Catal Lett, 2009;130;362-66.

4. S.P.Simner, J.F.Bonnett, N.L.Canfield,

K.D.Meinhardt,J.P.Shelton,V.L.Sprenk

le, J.W.Stevenson, J Power Sources,

2003;113;1-10.

5. Vasques C, Kogerler P, Lopez

Quintela MA, J Mater Res, 998;13:45.

6. Thirumalairajan S, Girija K, Ganesh V,

Mangalaraj D, Viswanathan C,

Ponpandian N, Cryst Growth Des,

2013;13;291-302.

7. Ravindranathan P, Komarneni S, Roy

R, J Mater Sci Lett, 1993;12:369-372.

8. Wenjun Zheng, Ronghou Liu, Dingkun

Peng, Guangyao Meng, Mater Lett,

2000;43;19-22.

9. Ting Liu, Yebin Xu, Mater Chem

Phys, 2011;129:1047-50.

10. Vladimir VS, Ruzica D, Marija M,

Nikolina P, Ivan S, Ljubica MN,

Evagelia M, Konstantinos G, Jan D,

Karel M, Process Application Ceram,

2010;4:127-34.

11. Sivakumar M, Gedanken A, Zhong W,

Jiang YH, Du YW, Brukental I,

Bhattacharya D, Yeshurun Y, Nowik I,

J Mater Chem, 2004;14:764-69.

12. Khetre SM, Jadhav HV, Jagadale PN,

Kulal SR, Bamane SR, Adv Appl Sci

Res, 2011;2;503-511.

13. G. Venkaiah, K.Venkateswara Rao, V.

Sesha Sai Kumar, Ch. Shilpa Chakra,

Int J Mater Methods and Technol,

2013;1(1);01-07.

14. S.M.Khetre, A.U.Chopade,

C.J.Khilare, S.R.Bamane, Int J Porous

Mater, 2011: 1(1) 1-5.

15. Yeon Hwang, Dae Sik Kang, Mi Hye

Park, J Ceram Process Res,

2010;11(3);397-400.

16. Zhou Kaiwen, Wu Xuehang, Wu

Wenwei, Xie Jun, Tang Siqi, Liao Sen,

Adv power technol, 2013; 24,(1);359-

363.

17. Tatsuo Fujii, Ikkoh Matsusue, Daisuke

Nakatsuka, Makoto Nakanishi, Jun

Takada, Mater Chem Phys,

2011;129;805-9.

18. Chandrashekhar PB, Ceram Silik,

2012; 56;127-9.

19. Sushmita Ghosh, Subrata Dasgupta,

Amarnath Sen, Himadri Sekhar Maiti,

Mater Res Bull, 2005;40:2073-9.

20. Sverre M Selbach, Mari-Ann

Einarsrud, Thomas Tybell, Tor

Grande, J Am Ceram Soc,

2007;90:3430-34.

21. Yongming Hu, Linfeng Fei, Yiling

Zhang, Jikang Yuan, Yu Wang,

Haoshuang Gu, J Nanomater,

2011;doi:10.1155/2011/797639.

22. Chao Chen, Jinrong Cheng, Shengwen

Yu, Lingjuan Chen, Zhongyan Meng, J

Cryst Growth, 2006;291;135-9.

23. Andreja Gajovic, Saso Sturm, Bostjan

Jancar, Ana Santic, Kristina Zagar,

Miran Ceh, J Am Ceram Soc,

2010;93;3173-9.



19

24. Haibo Zhang, Koji Kajiyoshi, J Am

Ceram Soc, 2010;93:3842-9.

25. Yonggang Wang, Gang Xu, Linlin

Yang, Zhaohui Ren, Xiao Wei,

Wenjian Weng, Piyi Du, Ge Shen,

Gaorong Han, J Am Ceram Soc,

2007;90;3673-5.

26. Qiu ZC, Zhou JP, Zhu G, Chen XM,

Yang RL, Song YH, Liu P, J Nanosci

Nanotechnol, 2012;12;6552-7.

27. Szafraniak I, Polomska M, Hilczer B,

Pietraszko A, Kepinski L, J Eur Ceram

Soc, 2007;27;4399-402.

28. Fruth V, Berger D, Lanculescu A,

Tenea E, Groza JR, Zaharescu M,

Sintering ’05, IP9,45-48.

29. Bellakki MB, Manivannan V, Madhu

C, Sundaresan A, Mater Chem Phys,

2009;116;599-602.

30. Biasotto Glenda, Simoes Alexandre Z,

Foschini Cesar R, Antonio Selma G,

Zaghete Maria A, Varela Jose A,

Process Appl Ceram, 2011;5;171-9.

31. Gao F, Chen XY, Yin KB, Dong S,

Ren ZF,Yuan F, Zou ZG, Liu JM,

Adv Mater, 2007;19:2889-92.

32. Sujana Kumari. U, Suresh. P, Prasada

Rao. A. V, Int J Appl Chem,2013;

9(1);51-58.

33. Sujana Kumari. U., Suresh. P., Prasada

Rao. A.V, Int Res J Pure and Appl

Chem, 2013;3(1),1-9.

34. Susumu Nakayama, asatomi

Sakamoto, Kimihiro Matsuki,

Yoshihisa Okimura, Rie Ohsumi,

Yusuke Nakayama and Yoshihiko

Sadaoka, Chem lett, 1992;2145-2148.



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