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SYNTHESIS AND CHARACTERIZATION OF ZNO MN DOPED

NANOPARTICLES NANORODS AND NANOBELTSAbhijeet Ojha1 Basant Choudhary Manoj Jangid Prof Kanan Bala Sharma

Centre for Converging Technologies University of Rajasthan jaipur-302004 Rajasthan IndiaDepartment of Physics University of Rajasthan Jaipur-302004India

Corresponding Author ojhaabhijeetgmailcom

Your name and the names of the people who

Abstract

Zinc oxide (ZnO) is a transparent wide bandgap

semiconductor compound (Eg = 337 eV) with a direct

electronic transition and has a large exciton binding energy

(60 meV) that ensures high luminescence efficiency at room

temperature Similar to GaN ZnO is considered as a

promising material for photonic devices working in the

ultraviolet and blue spectral regionsRecent studies have

shown that ZnO exhibits many novel nanoscale structures

such as nanorods nanowiresnanotubes nanoneedles

nanocombs and so forthwhich open up new prospects for

applications in micro-optoelectronic devices

In addition theoretical calculations have predicted

that transition-metal-doped ZnO materials may exhibit

room-temperature ferromagnetismThis offers opportunities

for developing spintronic devices combining standard

microelectronics with spin-dependent effects Such

spin-based devices are multifunctional and have very high

integration density ultra-fast data processing speed and low

electrical power consumption However to realize this idea

a thorough knowledge of the role of impurities and interaction

mechanisms taking place in doped ZnO materials is

essential

Experimental

Flow Chart of ZnO NPrsquos amp Nanorodes

Experimental Procedure Cont hellip

Synthesis of ZnO nanobelts The precursor was prepared from Zinc acetates and absolute

ethanol was refluxed at 80 0 C for 3hours The remaining

hygroscopic product is mixed with Mn impurity obtained from

01M Mn2+ were separated out and mixed with 014M LiOH

prepared in 100ml deionized water The precipitates were

separated out using centrifugal machine at 3500rpm

Samples were then dried in the oven at 80oC for 4 hours We

increase the concentration of LiOH from 01 M to 014 M by

doping so that the near neutral clusters are formed and

pH =8 This will helps to form long length Nanobelts

helps to form long length nanobelts

Cont hellip

Synthesis of ZnO nanorods - The precursor prepared from Zinc

acetates and absolute ethanol was refluxed at 80o C for 1hour under

oxygen atmosphere The remaining hygroscopic product is mixed with

Mn impurity obtained from 01M Mn2+ was separated out and mixed

with 014 M LiOH prepared in 100 ml deionized water The

precipitates were separated out using centrifugal machine at

4500rpm Samples were then dried in the oven at 80o C for 4 hours

PL Spectra that is found that the presence of impurities in nanorods

influences their PL spectra For Mn-doped samples (ZMO1 and

ZMO2) their PL spectra are similar to the spectrum of pure ZnO

There are two peaks at about 387 and 530ndash540 nm corresponding to

UV and visible emissions respectively The former is attributed to

exciton-related near-band-edge luminescence while the latter is

commonly referred to as a deep-leveltrapstate emission With

increasing Mn doping concentration (for ZMO2) the UV peak shifts to

a shorter wavelength (sim382 nm) but its intensity is still very strong At

wavelengths around 660 nm there is a hump in the PL spectra of

ZMO1 and ZMO2(assigned to an intrinsicdefect-induced emission)

Sample Data with Mn++ doping ConcentrationsThe notation and detailed description of the samples

studied in our work

---------------------------------------------------------------------------------

No Sample Descript Diffusion Diffusion Dopant

time(min) temperature conc

(C) (at )

---------------------------------------------------------------------------------

1ZnO Pure ZnO --- 850 -----

2ZMO1 Mn-doped ZnO 20 850 046

3 ZMO2 Mn-doped ZnO 40 850 115

4 ZMCO (Mn)-co-doped

ZnO 20 (Mn) 850 072 (Mn)

Morphological characterizations X-ray Diffraction (XRD) data for structural characterization of the

various prepared samples of ZnO were collected on an X-ray

diffractometer (PW1710) using Cu-K1048576radiation (1541)reveal long

length nanobelts ranging to a few micrometers in length and XRD

pattern reveal their high crystallinity Wurtzite geometry of ZnO was

confirmed as planes lt100gtlt002gt and lt101gt were obtained

Refluxing of precursor containing zinc acetate and ethanol for long

time results in long nanobelts of ZnO Addition of a catalyst stops

isotropic agglomeration of particles instead anisotropic

agglomeration occurs resulting in nanowires or nanobelts 01M LiOH

give positively charged nanobelts (pH = 65) whereas 014M LiOH

gives nearly neutral nanobelts (pH = 80)12 It is very much clear from

the SEM images obtained from two methods that positively charged

clusters results in deformation of nanobelts and nearly

neutral charged clusters results in long length nano belts

X-ray Diffraction Pattern (XRD) pattern of ZnO nanobelts

PL spectra of ZnO at different concentration

Results and discussion

Conclusionhellip

Applications amp Referenceshellip

Mn doped ZnO nanocrystals were synthesized using wet chemical

synthesis techniqueZnO nanophosphordoped with variable

concentration of Mn have been synthesized in the lab and

characterized using TEM and SEM Figs shows the fabricated ZnO

nanostructures Scanning Electron Microscope(SEM) image shows

the nanobelt which have a size around one millimeter Transmission

Electron Microscope(TEM) studies shows that the average diameter

of the particles is in between 25-100 nm and the diameter of the rod is

around 66 nm It is clear from the results that ZnMn nanostructures

are very sensitive to the preparation conditions and we can fabricate

any desired nanostructure High purity nanobelts of ZnO having

lengths in the range of several hundreds of micrometers to a few

millimeters have been synthesized in the laboratory SEM gives

beautiful results of the synthesized doped nanobelts Length of the

nanobelts varies from a few micrometers to a few millimeters XRD

patterns confirm the wurtzite crystal structure and high crystallanity

Zinc oxide nanostructures are of huge scientific and

technical interests because of their large excitonic binding

energy (EB) 60 meV and better thermal stabilities

Sample Preparation amp Exprimentation Synthesis of long length Mn doped ZnO nanoparticle

nanobelts amp nanorodes were carried out using chemicals

zinc acetate manganese acetate and absolute ethanol The

synthesis method was initially based on the experimental

procedure Alcohols are commonly used because the

solvent also act as a reagent However

the solvent does not participate in the reaction forming

ZnO from zinc acetate

Synthesis of ZnO nanoparticlesColloidal solution was prepared from Zinc acetate and

absolute ethanol 01M Zn2+prepared from Zinc acetate in

absolute ethanol was refluxed under distillation and stirred

for 3hours at 80 0C Desired proportion of manganese

impurity obtained from 01M Mn2+ prepared from Mn

acetate in 100 ml of ethanol01 gm of poly (N-vinyl -

2pyrroledone)(PVP) were also added in the reaction during

the synthesis process The concentration of PVP the capping

agent was kept at 01 gm per 10 ml of ethanol The

remaining hygroscopic product was mixed with 01M LiOH

prepared in 100 ml deionized water in which precipitates

started forming then precipitates were separated out using

centrifugal machine at 5000 rpm and then sample were dried

in vacuum oven at 800C

TEM Image of ZnO Mn nanorodTEM of ZnOMn nanoparticles

SEM Image of ZnO Mn nanobelt

Mn doped ZnO nanobelts have several applications and can be employed as best suit materials for spintronics gas sensors better insulation materials high energy density batteries etcReferences -[

1] B B Lakshmi C J Patrissi C R Martin ChemMater 9 2544

(1997)

[2] L Vayssieres K Keis A Hagfeldt S E Lindquist

Chem Mater 13 4395 (2001)

[3] C Pacholski A Kornowski H Weller Angew

Chem Int Edn Engl 41 1188 (2002)

[4] L Vayssieres Adv Mater 15 464 (2003)