B.A.R.C-1304

30O

X-RAY FLUORESCENCE ANALYSIS OF THULIUM OXIDE/OXALATEFOR RARE EARTH IMPURfTlES

A.r

!.. C. Chandoia and P. P. Kh.innaSpeciroscopy Division

1986

B.A.R.C. - I30K

GOVERNMENT OF INDIAATOMIC ENERGY COMMISSION

UOS<co

X - R A Y FLUORESCENCE ANALYSIS OP T H U L I U M O X I D E / O X A L A T E

FOR RARE E A R T H IMPURITIES

by

L .C . Chandola and P.P. KhannaSpectrosropy Division

BHABHA ATOMIC RESEARCH CENTREROMHAY, INDIA

1986

BARC-1304

INIS Subject Category,: B11.20

Descriptor 8

THULIUM OXIDES

OXALATES

IMPURITIES

RARE EARTHS

X-RAY FLUORESCENE ANALYSIS

QUANTITATIVE CHEMICAL ANALYSIS

BORIC ACID

ACCURACY

.SENSITIVITY

A B S T R A C T

An x-ray fluoraacenoa apactroaatrio Method for tha analyaio

of thulium oxide la described, tor tha analysis, the eample In

oxalate fora la mixed with borlo aold binding material and preaeed

Into a pallet over a eupportlng pallet of borlo aold. A wavelength

dlaperalTe fhillpe PW 1220 X-ray fluorescence apeetroaeter la uaed

for the experlaentai the minium determination llmlta are O.OO25C

for Hof £u and Tf 0.005/^ for Vj and Sr and 0.01^ for Tb. Calcula*

tiona for theoretical minlmua detection llmlta and percent atandard

deviation at each oonotntratlon of the atandard are carried out.

x<4UT ntrosEsoarci UALTSIS or THULHW antx/ounatJOB RABE BAMH IMPURITIES

by

£.0 . Chaadola and P.P. JQM&aa

I . IRBGDOOXIOV

Pura thullua (Xa) la l lkaly to oontaia Df, Re, Mr, l a , La and I

aa laBurltlaa l a I t . laara ara no aarlier raporta oonoandac Z>ray

fluoraaoaaoa (ZHf) analyata at Ta. Hcwarar, thara la ona optloal

aalaaloa •paotrographlt (OBS) oathod daralopad by Xnlaaly at a l '

for tha aaalyala of thullua oxld« to dataralna Ho, Kr, Tb, £u aid T

la tha ooaoaatratloB ranga 0.02-1^. Wa aanra m ooatlauimf profraaaa

of daraloplac aanaltlra XB9 aathoda for tha analyala of al«*

parity rara aartha ( H a ) . la oontlauatlon of thla pragraaaja aa

XBf aathod aaa aaaa daralopad for tha aaalyal nt thullua oxlda.

tha aathod bala( raportad la aora aanaltlva than tha aarllar raportad

CSS aathod. flia alalaua dataralnatloD limit (am) of tha aathod balaf

raportad la 0.002^ for Bo, Lu and T; 0.005^ tat Dy and *r aad 0.01)<

for Yb. OataralaatiOB of ly In thla aatrlx waa aot triad by

aarllar OBS workara and It la bain* raportad hara for tha Xtrat tlaa.

Apart froa battar aanaltlTlty la tha praaant oaaa, th* W aathod

haa an advaatafa orar CE3 mathod that It dlapanaaa wltfe tha ooatly

ooaauaablaa Ilka photographlo pl«t*a, aigb purity alaotrodaa ato.

ZZ.

II. 1 Mataod

Bi« toullua oxlda aaaple la eosTartad to thullua oxalata by

dlaaolutlon In altrlo moid and praolpltatlon with oxallo add. 450 ag

of 417 oxalata powdar la alxad well with 150 ag of boric aold powdar

binding aatarlal. Saa alxtura la praaaad to ton. a i£ lack dlaaatar

doubla layar ptllat orar about 4 ga of borio aold aaoklnc pallat.

Ska aaapla mataoa ia irradiatad with high lataaaitgr X-ra/a fro* a

tuofatan targat X-ray tuba aad tha fluoraaoani X-raya ara aaalyaad

by a Lif(200) exyatal. A < latanoltiaa of cfaaxaotariatie I . I-raya

of Ztf( Ha, Br, Ib aad £u ara seaaurad by a flow proportional ooimtar

whlla that of X X-ray of I la aaaaurad by a selntillatloa oountar.

Staadarda ara praparad aynthatloally by adding know* aawrtta of IX

ozida aolutiaa to thulium oxlda aolutloa aad praolpltatiag thaa aa

oxalataa. Iha baokgrouad iataoal»laa ara aaaaurad on a pura thullua

oxid* pallat at tha 2 ' anglaa of lapurlty alaacnt X-raya and ttiaaa ara

aubtraetad froa tha total oounta to arrira at tha aat oounta* Dia

nat oounta for at^jadarda ara plottad againat thair ooneantratloa to

obtain tha working ourraa for dlffarant alaaanta. tha oonoantratloa

of tha lapurity la a aaapla la obtainad by raadlng tn« T»1U» of nat

oounta fro* tha approprlata working ourra.

II.2 reparation of Standard* and Saaplaa

Bara aarth oxldaa of Iy» Ho, Er, Ybf Xu and T obtalaad froa

Sara Earth Produeta Ltd.* Chaahlra, England, ara dlaaolvad in altrlo

(3)

•Old (tt.H., llerck) an£ three standard eolutloee containing 500y/al,

50 V/al and 5 V/al of each rare earth oxide are prepared. Appropriate

aaounte act a-0* •*• wtigaed out separately sod dlaaolred la nitric

•old to VL&lch til* individual rare earth aolutlona are «dd«d« Bi«

atendarda prapared contalntd blank (no inpuritiae addad), 20,50,100,

200, 500, 1000, 5000 aad 10,000 ppa bjr weigjjt ot each raxa •arth oxlda

in *"2°3' nt«aa ataodard aolutions ar« than pr«cipitat»d aa oxalataa

by • aaturatad solution of oxalic acid. Th* preclpitataa ara filt«rad

and dried. 450 ag of dry oxalate ia mixed with 150 ag of boric acid

binding a»t»rial aid ground in aa agata aortar. SQila alxtura la

pre a«d at a praaaura of 20 tonsva to obtain a doubla layer pallet.

The oxld« aaapla la converted to oxalate aad treated aiailar to

the ataadarda to obtain a li inch dia. pellet.

11.3 Saapla to Binding Material Ratio and Saturation Bilolmeaa

Experlaenta

To ccmaerre the aaouat of »«unpl« needed for the asalyaia,

the double layer technique ia adopts. In order that the sample

doee not peel off from the backing pallet of boric acid, the eaaple

ia nixed with boric acid in the weight ratio 3s1. This ratio of

•ample to binder vraa found to be useful in our earlier worka '

and therefore retained for this analysis also.

(4)

Experiment* were dooe to find out the minimum weight of •ample-

binder mixture (3:1) vfclch will give saturation thickness when can-

Terted to a l i Inch diameter double layer pallet. Double layer

pellets over 4 g borio acid were prepared with 50,100,200,400,600,

1000 and 1500 mg sample-binder mixture of a 800 ppm ntandard*

Intensities of BK elements contained in the standard were measured

for 40 a (for Y-100 a) . The results of these studies are plotted

in Pig.1. From these studies i t was concluded that a 400 mg mixture

gives saturation thickness for the impurity X-rays. However, taking

a safety faotor, the minimum weight of the mixture waa fixed at

600 mg.

A fixed amount (4g) of borio aoid aa backing material 1B uaed la

the preparation of double layer pelleta since the quantity of backing

material contributes to the scattered X-raya for bard K^ l i sa of T.

II .4 Iaatruaent iwd Operate "f Conditions

A aeaiautooHtlo X-ray fluoresoenoe epeotreaeter Ihllipa model

Ft 1220 la use* for the analysis t out of the three crystals i t can

hold at a tine, fee 117(200) was found to ba suitable, tte Unatrument

haa a choice of two oolllmatore (480 *.m and 160MJI) and two deteotors

(flow proportional and sointi l lation). B»e inatrumant haa 4 portholea

for samples eaoh of which can hold a tablet of l i inch diameter. The

aaapla can be kept rotated or stationary and the X-ray path can be

(5)

evacuated If needed* Zhe conditions eelected for the analyst* are

given la Table-!. The wavelengths of selected analytical llnee are

given in Table II. It was possible to uee L A lines for Vy, Ho, Er, Tb

and Lu, «taereas for Y, the Ij line was used. A strip chart record

ot 1% standard is given in fig.2 where the impurity lines of analyte

elements are Marked.

III. HESD1TS

III.1 Workt«w Curves

The working curves relating the concentration of analyte

elenent oxide with net intensity (>L-*b) •*• eh own in figs. 5 sad 4.

The net Intensity is obtained by subtracting the counts obtained

froa a blank (*v) XTOM tot.nl oounts (l ) at 29 angle of each analyte.

A blank reading Is teken after every three readings so that any

variation la intensity with ti»e Is corrected for in the observations.

The average net oounts for different saalyte elements la each

standard are given in Table III.

III.2 Precision

The precision of the aethod was calculated la teras of percent

standard deviation (ss£). Initially the net counts (• - 5b) *re

obtained for 11 sete of reading, from these <rn t i* caloulated by

(6 )

2 4-using the foraula (£d /u-O" rtiere d la individual difference of aetoouat tram the average of a readings, finally SD$6 i s obtained ittiob.

Is equal to (<r .)HOO/(l - I . ) . The precision so calculated for sacknet p b

analyte element at each oonoentratlon of the standard la given ia

Table IT.

III.3 Theoretical Mjnlaun Detection Halts

A concentration which gives a signal equal 1>« three tiaes the

standard deviation of background ia taken as theoretical ainlaw

deteotion limit (TMDL). this i s calculated using the fornila.

1MDL - 3 ( l b ) x oan<j«ntrstton/(l-*b)« O»« ealouUtad

Taluta ara listed la Table V.

ACKHOWLEDQEMBHT3

the authors expreea their ainoera thanka to Dr. 8.1.1.6.

Head, Spectroacopjr DiTieion, for hie keen interest in the work sad

valuable guidanoe. Ifcenka are also due to Shrl B.M. Agrawal and

Dr. B.M. Dixit for help at varloua stages during the oourae of this work.

- 7 -

RSfEEKIfCES

1. B.B» Khicely, V.A. Faseel, R.W. Tabeling, B.G. Hurd and B.B.Qulney

Determination of rare earth lapuritlea commonly aaaoclated with

purified TB, Yb, Xu and Sc.

Speetrochla. Acta JQ, 300 (1958).

2 . R.M. Dixlt and S.S. Deebpande

Deteradaation of C«f Pr, Nd and Sa in higfc purity laathanua dxld*

by X-ray fluoreac«nc«

Ctaaada inalitycwia 2 i , 1353 (1976).

3 . l . C . Chaadola, I . J . Machado and A.I . Mobil*

Deterattnatlon of rare earth impuri t i ta in cariu* diozida and

oxalate by X-rey fluoreeoenc* ttchnique

J. Radioanal. Gbea. %., 369 (1976).

4. L.C. Chandola and A.N. Mobile

Determination of rare earth impuritiea in praeeodjraluB oxide and

oxalate by X-ray fluorescence tedinique

Current Sc i . 46 , 299 (1977).

5. 1'C. Cbando7a and A.H. Mohile

X-ray fluoreacence spectroie tr io analyaie of neodymiua exlde

and oxalate for trace rare earth iapuritiea

Indian J. Pure & Appl. Ehyeico J 6 , 651 (1978).

6. R.M. Dixit and S.S. Seahpande

X-ray fluoreacence analyaia of Y, Ce, Pr, Sd t Eu and 6d

in high purity samarium oxide.

Treeeniua Z.Anal. Cbea. 29J2, 375 (1978).

- 8 -

7* R.M, Dixit and S.S. Deehpande

X-ray fluorescence determination of Pr, Nd, Sm, Qd» Tb, Jy end T

in high purity europium oxide

fieport BAfiC - 1275 (1985)

8* H.M. Dixit and S.S. Deehpande

X-ray fluorescence determination of Sa, Eu, Tb, Iy, Hot Ib and T

in hlgji purity gadolinium oxide

TreBcniua Z. Anal. Chen. 287.* 132 (1977).

9* l .C . Chandola, I .J . Katfiado and A.If. Uohile

X-ray fluorescence analypl* of terbium oxl4« and oxdate for

rare earth in^urities.

Mikrocbim. Acta (Wieu) I I , 399 (1976$.

10. H.M. Slxit and S.S* Deahpandc

X-ray fluorescence analysis of high purity dyaproaiua oxid«

for Y, Eu, Od, Tb, Ho and Er.

Vraaenius Z. Anal. Chem. OJ, 111 (i960).

11. fi.Jf. Sixlt and S.K. Kapoor

X-ray fluoreacence analysis of higji parity k«lstlu« oxide for

common rare earth iapurlties

£reseniua Z. Anal. Cbeo. 226, 394 (1979).

12. £ .0 . Cbacdola and P.P. Xhanna

X-ray fluoreecenoe spectroatrio analyala of erbiua oxide far

rare earth impuritieo

J. Badioanal. & Hud. Cbea. ^ 1 , 157 (1985).

13« ii.O. Chandola and P.P. KhannaX-ray fluor*se«ncs analysis of yttsrblua oxia«/Qnlat« for

rare earth iapuritita

Haport BXHO - 1176 (1982).

H . L.C. Chandol* and P.P. Xhanna

X-ra/ Xluor*ac«Doa analysis of lutatiua oxid«/onlat« for

rara sartb lapurltias

Rsport BAJRC > 1264 (1985).

1$. B.H. Dirtt and S.S. D*»hpande

As XBf asthod for ths detsrainatlon of ooousao rara sarth

iapuritiaa In hlgi purity yttriia oxida

Trsssnlua 2. inal. Ctasm. 2 ^ , 180 (1977).

- l o -

APPARATtfg Ajff qPKSAtiyQ COMIITIOMS JOB TffE ANALYSIS

1. Spectrometer

2 . Generator

3. X-ray tub*

4- Colllmator

5» X-ray path

6. Detector

7. Pulse Height•election

8. Counting tlae

Philips semiautomatic X~ray fluoreaceooe

Spectrometer P» 1220.

Philips ultrattable generator Ft 1140

Toltage and current regulated to O.OljC

3 kW tunget«a target tube operated

at 60 kV and 39 a*-

Pine (160Mm) for Dy, Ho, Er, Tb aid Lu

Ooarse (48CJU.») for Y.

Vacuum 0.$ tone*

H o w proportional operating on 90$ Ar

+ \O% CH. gaa for eleo«nt» By, Bo,

Scintillation Sal (Xl) type for Y.CH. gaa for eleo«nt» By, Bo, Br, Yb and 1Mi

for VPC; Base 300, Window 350

tor S.C.j Base 200, Window 450.

40s for Dy, Ho, Er, Tb «cd Xu

100B tor Y.

9. Analysiag Crystal Ll?(200). All element a in I order

10. Sample spinner On

-n-

BJUTOB J 0 1

or ram&w axxm

Ho

Ir

Lu

I

(Uf-200)

56.85

54.67

52.7

49.28

47.57

23.62

tawgjk*T

1.90881

1.84500

1.78425

1.67189

1.61951

0.63024

S

6

6

7

7

14

.494

.719

.947

.414

.654

.931

0.005

0.002

0.005

0.01

0.002

0.002

- 1.0

- 1.0

- 1.0

- 1.0

- 1.0

- 1.0

TABU-III

Standard%

1.0

0.5

0.1

0.05

0.02

0.01

0.005

0.002

122,955

62,355

13,822

9,550

4,139

2,046

869

-

MBAI NET

a*

200,919

102,456

36,683

16,507

9,751

4,731

2,348

1,003

COUNTS KB STASBABIS

Ueaa nat counts

Br

203,669

104,53$

35,784

17,940

9,043

4,374

1,988

m

92,066

46,557

15,009

7,349

5,211

1,987

-

Lu

165,312

64,166

28,147

14,324

7,101

3,652

2,099

1,141

r

319,882

161,605

59,786

29,135

15,235

8,027

4,211

2,215

-1 3 --

TABLE-IT

IKHCEHT STANDARD JEVIATIOg

Stand**! J r Ho Sr Tb Lu

1.0

0.$

0.1

0.03

0.02

0.01

0.003

0.002

0.3

0.5

1.5

1.8

4.0

7.5

18.2

-

0.5

0.6

1.0

2.7

3.3

4.4

12.5

20.9

0.4

0.7

2.0

3.4

6.4

13.3

28.1

-

1.5

1.6

3.9

8.7

13.3

26.8

-

-

1.3

1.4

1.3

2.4

4.7

9.4

17.2

31.1

0.4

0.6

1.8

2.5

4.5

8.8

16.1

34.6

9RB0RKTICAL SHBGIIOK LIMIT CALCIIIATICWS

—

*

I *

i r

Tb

X«

r

fat Cavartt*

9,550

16,507

17,940

7,349

14,324

29,135

Blank oauata

17,647

18,026

33,925

65,456

27,785

23,961

132.8

137.2

184.2

255.8

166.7

154.8

398.4

411.6

552.6

767.4

500.1

464.4

ppm

20.9

12.5

15.4

52.2

9.0

8.0

» 500 ppa •Undu4

« Yb

0 50100 200

Er

SAMPLE iBORiC ACID:: 3:1800 ppm STANDARD

400 600—SAMPLE mg -

FIG.I. SATURATION THICKNESS STUDIES ON DOUBLE LAYERPELLET OVER BORIC ACID

-u-

59 55 51 47— T W O THETA DEGREES

FIG.2. STRIP CHART RECORD OF 1%IMPURITIES IN THULIUM OXIDE

8

\0

20 50 100 200 500 1000CONCENTRATION IN ppm — —

FIG.3. WORKING CURVES FOR Dy,Ho ANO Y

5000 10000

io

20 50 100 200 500 1000 5000 10000CONCENTRATION IN p p m — • -

FIG. 4. WORKING CURVES FOR Er, Yb AND Lu

<• • •> v

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