ARTICLE IN PRESS

hyschem

Radiation Physics and Chemistry 75 (2006) 301–308

www.elsevier.com/locate/radp

Abstr

1. In

0969-

doi:10

fax: +

E-

i

Cerium (IV) molybdate cation exchanger:Synthesis, properties and ion separation capabilities

A. Nilchi�, B. Maalek, A. Khanchi, M. Ghanadi Maragheh, A. Bagher

Jaber Ibn Hayan Research Laboratories, Atomic Energy Organization of Iran, P.O. Box 11365/8486, Tehran, Iran

Received 29 December 2004; accepted 23 July 2005

act

ared at

ysis, IR

H)2(H-

alue of

o and

V) were

Mg(II)

orption

Nuclear

A description of the preparation and properties of an H+ form of cerium (IV) molybdate ion exchanger prep

different pH values is given. The material was characterized by inductively coupled plasma (ICP) elemental anal

spectrometry and thermo-gravimetry and titration curve analysis; its composition was found to be Ce(O

MoO4)2?nH2O. It was also observed that the exchange capacity of the ion exchanger depends upon the pH v

the ceric solutions used and its value was lowered after gamma irradiation. Furthermore, the absorption of 99M

the distribution coefficient of this ion exchanger for Mg(II), Ba(II), Ca(II), Ni(II), Mo(VI), Cr(VI) and Th(I

investigated. It was found that cerium (IV) molybdate had the highest absorption for Th(IV) and Ba(II), while

and Ca(II) showed the lowest absorption, respectively. Finally, gamma irradiation, in general, lowered the abs

of the cations being investigated in this study.

r 2005 Elsevier Ltd. All rights reserved.

Keywords: Inorganic ion exchangers; Distribution coefficient; Ion-exchange capacity; Radiation stability; Elution curves;

technology

troduction

nic

at th

oura

ds h

e alt

diffic

(Nil

of

olut

elut

eatm

of wastes and in processes for recovery of metals from

en used

plating

als are

conven-

ving in

alt type

, tung-

rsenates

tanium,

, 2004;

va and

ies on

ported.

The resurgence of interest in synthetic inorga

exchangers has largely stemmed from the fact th

materials can be used under conditions unfav

towards organic resins. Their resistance towar

and ionizing radiations makes them attractiv

natives towards certain ions, a number of

separations can conveniently be carried out

et al., 1999, 2000, 2002, 2003). The ability

exchange materials to remove trace ions from s

and the concentration which may be achieved on

with suitable solutions have been used in the tr

�Corresponding author. Tel.: +9821 61384341;

ws ion

creases

806X/$ - see front matter r 2005 Elsevier Ltd. All rig

.1016/j.radphyschem.2005.07.003

98 21 638749.

mail address: anilchi@aeoi.org.ir (A. Nilchi).

ion

ese

ble

eat

er-

ult

chi

ion

ion

ion

ent

very dilute solutions. Ion exchangers have be

extensively in treating rinse water wastes in

industry for example, where valuable met

recovered at costs comparable to or less than

tional chemical treatment, with appreciable sa

space for treatment plant.

Recently, a number of ion exchangers of the s

have been reported, these include phosphates

states, molybdates, antimonates, vanadates, a

and similar salts of thorium, zirconium, ti

cerium, tin and other metals (Nilchi et al.

Amphlett, 1985; Gal and Gal, 1985; Chekomo

Cherednichenko, 1998). A number of stud

molybdic-acid-based ion exchangers have been re

Molybdic acid (Clearfield et al., 1973) sho

exchange properties and the uptake of cations in

hts reserved.

with increasing pH. Although the exchange behaviour of

e be

ly be

cal a

istrib

cert

Ba(

washed with deionized water and air-dried. The product

h size.

s deter-

0mL of

table in

h metal

olution

ARTICLE IN PRESSA. Nilchi et al. / Radiation Physics and Chemistry 75 (2006) 301–308302

the molybdates of some metal cations hav

explored, cerium (IV) molybdate has relative

untouched. In this paper, the synthesis, chemi

thermal stability, gamma irradiation, and the d

tion coefficient of the ion exchanger towards

ions, namely Mo(VI), Cr(VI), Th(IV), Ni(II),

Mg(II) and Ca(II) are examined.

2. Experimental

alyti

rad

Th(I

rmin

Nucl

f Ira

tt p

ecord

ogra

t mo

btain

oup

am

oni

repa

sam

ate a

e pH

SO4

ith

It w

d wa

ogen

as th

tration

affected

cerium

metal

Ba(II),

er were

in a

omplete

of each

4mL of

100mL

ach ion

Plasma

mn that

s bottle

low the

lectrode

H was

out, by

f about

.

ed with

All the reagents and chemicals used were of an

grade obtained from Merck or Aldrich. 99Mo

isotope and ionic solutions of Mo(VI), Cr(VI),

Ni(II), Ba(II), Mg(II) and Ca(II) used for dete

distribution coefficient values were supplied by

Research Centre, Atomic Energy Organization o

The pH values were measured using a Scho

meter, model CG841; the infrared spectra were r

using a Perkin-Elmer spectrophotometer; therm

metric analyses were carried out using a DuPon

951 thermobalance, the elemental analysis was o

using a Perkin-Elmer model 5500 Inductively C

Plasma Spectrophotometer and finally an Ortec G

Spectrometer was used.

2.1. Preparation of cerium (IV) molybdate

The effective concentration of ceric amm

nitrate and ammonium molybdate used in the p

tion of seven samples are given in Table 1. The

was prepared by mixing ceric ammonium nitr

ammonium molybdate at room temperature. Th

the ceric solution was adjusted with 0.1M H2

0.80, 0.50 and 0.15. The precipitate in contact w

liquid was left overnight at room temperature.

then filtered, washed with 0.1M H2SO4, deionize

and air-dried. The sample was converted to hydr

immersing it in 1M HNO3 for 48 h, and w

a dose

stigated

) of the

ibution

changer

values

A 0.2 g

lutions

vessel.

Table 1

The preparation conditions used

Sample no. pH of Ce4+

solution

Concentration (M) Mixi

ratio

Ce/MCe4+ Mo6+

1 0.80 0.05 0.10 0.50

2 0.50 0.05 0.10 0.50

3 0.15 0.05 0.10 0.50

4 0.15 0.05 0.2 0.25

5 0.15 0.05 0.15 0.33

6 0.15 0.25 0.25 1.00

7 0.15 0.10 0.05 2.00

en

en

nd

u-

ain

II),

cal

io-

V),

ing

ear

n.

H-

ed

ve-

del

ed

led

ma

um

ra-

ple

nd

of

to

the

as

ter

by

en

was then ground and sieved to appropriate mes

2.2. Chemical stability

Chemical stability of the ion exchanger wa

mined by dissolving 0.1 g of the exchanger in 5

different solvents for 24 h. The exchanger is s

water and in solution of alkali and alkaline eart

salts. On refluxing with water, a milky colloidal s

is obtained. It completely dissolved in 4M concen

of acids, while in alkalic solutions it remained un

up to a concentration of 0.1M.

2.3. Distribution coefficient, Kd

For distribution coefficient studies, 0.2 g of the

molybdate ion exchanger and 0.5mL of 0.005M

ion solutions of Mo(VI), Cr(VI), Th(IV), Ni(II),

Mg(II) and Ca(II) and 19.5mL of deionized wat

added in different vessels and were placed

thermostated shaker at 25 1C for 5 h to attain c

equilibrium. The mixture was filtered and 10mL

solution was poured into separate bottles and

HNO3 concentration was added and diluted to

with deionized water. The concentration of e

metal was determined by Inductively Coupled

analysis.

2.4. Titration of ion exchanger

Cerium molybdate (0.2 g) was placed in a colu

was fitted with glass wool at its bottom. A glas

containing 20mL of 0.001M HCl was placed be

column, and for determination of pH, a glass e

was placed in the solution, then 70mL of NaO

poured into the column. Titration was carried

passing the NaOH solution at a drop rate o

0.3mL/min, and continued to a pH of about 13

2.5. Radiation stability

Cerium molybdate in H+ form was irradiat60Co source for the total of 50 and 200 kGy at

rate of 0.484Gy/s. Radiation stability was inve

by determining the ion exchange capacity (IEC

solid before and after irradiation.

2.6. Absorption of 99Mo on cerium molybdate

In order to determine the absorption and distr

coefficients of 99Mo on cerium molybdate ion ex

at different media, solutions with different pH

were prepared and placed into different vessels.

of cerium molybdate and 19.5mL of various so

with different pH values were added to each

ng

o

A 0.25mL of 99Mo was added to each vessel, and then

h. T

olut

le w

bands at 365 and 890 cm�1 show the presence of

can be

e–O–H

ge was

dose of

urve of

ARTICLE IN PRESSA. Nilchi et al. / Radiation Physics and Chemistry 75 (2006) 301–308 303

placed in a thermostated shaker at 25 1C for 3

solutions were then filtered and 5mL of each s

was removed and the activity of each samp

counted by gamma spectrometer.

3. Results and discussion

n cu

ysis,

s be

ed a

infra

ion

00 cm�1. T

istics

ows

00 cm

ows

bserv

due

on a

ally

molyb-

changer

al water

300 1C,

ps take

nic ion

eight is

e curve

e up to

nted by

loss of

alue of

ated by

nger by

olecular

ives the

On the basis of infrared spectrometry, titratio

analysis, thermal studies and ICP elemental anal

molecular formula of cerium molybdate ha

determined.

Fig. 1 shows the IR spectrum of unirradiat

irradiated samples of the ion exchanger. The

spectrum shows a broad band in the reg

3000–3650 cm�1, sharp peaks at 1610 and 11

and a weak broad band in the region 500–800 cm

peaks at 3400–3650 and 1610 cm�1 are character

O–H stretching and bending mode, and hence sh

presence of lattice water while the peak at 11

corresponds to M–O–H bending mode which sh

presence of Ce–O–H. As such, the broad peaks o

in this compound at 550, 610 and 840 cm�1 are

the overlapping of the bands of molybdate i

Ce(OH)2+ in the regions of 500–800 cm�1 and fin

Fig. 1. IR spectra of (a) unirradiated and irradiated samp

50 kGy. (Curves b and c are shifted up, as related to transm

he

ion

as

rve

the

en

nd

red

of�1

he

of

the�1

the

ed

to

nd

the

molybdate ion. Hence, from the IR analysis, it

deduced that H2O, �OH, molybdate ion and C

are present. Furthermore, no significant chan

observed in the irradiated samples up to a total

200 kGy.

Figs. 2 and 3 show the thermogram and DCS c

cerium molybdate. The thermogram of cerium

date suggests that the weight loss of the ion ex

up to 150 1C is due to the removal of free extern

molecules. At higher temperatures up to

condensation of exchangeable hydroxyl grou

place, which is characteristic of synthetic inorga

exchangers. Above 300 1C the gradual loss in w

due to the removal of structural water. Th

pattern suggests that the ion exchanger is stabl

800 1C. The 11.2% weight loss of mass represe

the TGA curve at 100 1C must be due to the

nH2O from the ion exchanger structure. The v

‘‘n’’, the external water molecules, can be calcul

18n ¼X ðM þ 18nÞ

100,

where X is the percent weight loss in the excha

heating up to 100 1C, and (M þ 18n) is the m

weight loss of the material. The calculation g

les of cerium (IV) molybdate. Total dose absorbed (b) 200 kGy and (c)

ittance).

value of 4 for the external water molecules (n) per

Mo

s m

ratio

e abo

4)2?

ceri

nts

hrou

ows

n. T

po

indicating that the ceric molybdate behaves as mono-

. 5) and

of this

trations

n. As a

tandard

on and

curves

tion of

Cl. The

slowly,

reciable

ed with

m gives

ARTICLE IN PRESSA. Nilchi et al. / Radiation Physics and Chemistry 75 (2006) 301–308304

molecule of the exchanger.

The concentration of two elements of Ce and

2� 10�2 g/L of cerium molybdate solution wa

sured by ICP elemental analysis, and the molar

Ce/Mo was found to be 0.44. As a result of th

findings, a tentative formula of Ce(OH)2 (HMoO

H2O has been assigned to the exchanger.

Fig. 4 shows the pH-titration curve of the

molybdate. In this figure, the X-axis represe

number of millimoles of 0.01M NaOH passed t

per gram of cerium molybdate; and the Y-axis sh

pH value of the effluent passed through the colum

pH titration curve shows only one inflexion

Fig. 2. Thermogram of cerium (IV) molybdate.

Fig. 3. DSC cur

in

ea-

of

ve

4-

um

the

gh

the

he

int

functional.

The effect of the concentration of NaCl (Fig

equilibration time (Fig. 6) on exchange capacity

compound shows a constant capacity at concen

greater than 0.6M and after 48 h of equilibratio

result the exchange capacity was determined by s

method (Samuelson, 1965) in 1M salt soluti

samples are equilibrated for 48 h. The elution

(Fig. 7) show that practically complete elu

hydrogen ions take place in 100mL of 1M Na

elution is fat at the beginning and then decreases

becoming insignificant after 100mL. No app

change in the capacity of the sample is observ

increasing pH (2–10). This exchanger in acid for

a buffer system of pH 2–3.

ve of cerium (IV) molybdate.

0

2

4

6

8

10

12

14

0 5 10 15 20 25 30 35No. mmoles of 0.01M NaOH

pH

Fig. 4. The pH-titration curve of cerium (IV) molybdate with

0.1M NaOH.

The ion exchange capacity of seven samples of ceri

red

apac

ns. T

ampl

precipitated at pH ¼ 0.15 has higher capacity than

er, the

e effect

mixing

change

:1 ratio.

ingoing

shown

s. It can

bivalent

ith the

us ions

repared

he Kd is

tion, Fc

passing

ed (mL)

ARTICLE IN PRESS

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1 1.2Molarity of NaCl

Exc

hang

e ca

paci

ty,

meq

/g

Fig. 5. Exchange capacity as a function of NaCl concentration.

0

0.2

0.4

0.6

0.8

1

0 10 20 30 40 50 60 70 80

Equilibration time, hr

Exc

hang

e ca

paci

ty,

meq

/g

Fig. 6. Effect of equilibration time on exchange capacity.

0

1

2

3

4

5

6

7

8

9

0 20 40 60 80 100 120 1Effluent, mL

Elu

tion

of [

H+

] (v

olum

e of

0.0

1 N

NaO

H)

eluant 1.0 M NaCl

Eluant 0.1 M NaCl

Fig. 7. Elution curve of hydrogen ions for ceric molybdat

Table 2

The ion exchange capacity (IEC) of cerium molybdate ion

exchanger precipitated at different pH values with 0.1M NaCl

Sample no. pH IEC (meq/g) Mixing ratio

1 0.15 5.27 0.50

2 0.15 3.30 0.33

3 0.15 2.40 0.25

4 0.15 1.70 1.00

5 0.15 2.90 2.00

6 0.50 4.24 0.50

7 0.80 3.67 0.50

Table 3

Effect of size and charge of the exchanged ion on the exchange

capacity

Exchanged ion Hydrated ionic

radius (pm)

Exchange capacity

(mequiv/g; dry mass)

Li(I) 340 0.35

Na(I) 276 0.60

K(I) 232 0.75

Mg(II) 700 0.43

Ca(II) 630 0.53

Sr(II) 610 0.65

Ba(II) 590 0.73

A. Nilchi et al. / Radiation Physics and Chemistry 75 (2006) 301–308 305

molybdate ion exchanger which were prepa

different pH values is given in Table 2.

The results show that the ion exchange c

depends on the pH value of the ceric solutio

capacity increases with decrease in pH values; s

um

at

ity

he

e 1

sample 7 precipitated at pH ¼ 0.80. Howev

concentration of the solutions mixed have littl

on the exchange capacity. Sample 1 obtained by

ceric and molybdate in 1:2 ratio has a higher ex

capacity than sample 5 obtained by mixing in 2

The effect of the size and charge of the

hydrated ion on the capacity of the exchanger is

in Table 3 for alkali and alkaline earth metal ion

be seen clearly that for univalent as well as

cations, the exchange capacity increases w

decrease in hydrated ionic radii.

The value of Kd measurements for vario

studied using cerium molybdate ion exchanger p

at different pH values are given in Tables 4–6. T

defined by

KdI c � F c

F c�

V

MðmL=gÞ,

where Ic is the initial concentration of ion in solu

the final concentration of ion in solution after

from ion exchanger, V the volume of solution us

40

e.

and M the weight of exchanger in contact with VmL

ate ion

to have

studied

he ion

V) and

I). The

h(IV)4II).

ibution

ellings,

l bond,

solvent distribution and nature of the ion exchanger.

value of

stigated,

hemical

o(VI),

I) from

(II) and

of this

s which

cerium

ric and

xchange

Gy are

hich are

radiated

cient of

ate ion

that the

e lower

studied

is also

ve the

I)4Cr

ame as

ARTICLE IN PRESS

Table 5

Distribution coefficient measurement of various catio

pH ¼ 0.5

Cations Kd (mL/g)

Mg(II) 4.0

Ca(II) 63.0

Ba(II) 1910.0

Ni(II) 34.5

Cr(VI) 74.0

Mo(VI) 22.1

Th(IV) 4399.5

Table 4

Distribution coefficient measurement of various catio

pH ¼ 0.8

Cations Kd (mL/g)

Mg(II) 1.3

Ca(II) 36.8

Ba(II) 1204.2

Ni(II) 22.7

Cr(VI) 7.0

Mo(VI) 20.6

Th(IV) 4237.2

Table 6

Distribution coefficient measurement of various cations,

pH ¼ 0.15

Cations Kd (mL/g)

Mg(II) 17.0

Ca(II) 65.0

Ba(II) 6341.0

Ni(II) 40.0

Cr(VI) 81.0

Mo(VI) 99.6

Th(IV) 11 722

0 20 40 60 80 1000123456789

Volume of effluent (mL)

Rel

ativ

e im

puls

es

(a) (b)

Fig. 9. Elution curve of separation of Th(IV)–Mg(II): (a)

deionised water, 0.1mL/min; (b) 0.5M HCl, 0.4mL/min; 2.5 g

of cerium molybdate.

0123456789

0 20 40 60 80 100Volume of effluent (mL)

Rel

ativ

e im

puls

es

(a) (b)

Fig. 8. Elution curve of separation of Th(IV)–Mo(VI): (a)

deionised water, 0.1mL/min; (b) 0.5M HCl, 0.4mL/min; 2.5 g

of cerium molybdate.

A. Nilchi et al. / Radiation Physics and Chemistry 75 (2006) 301–308306

solution/g

Tables 4–6 show that the cerium molybd

exchanger prepared at lower pH value tends

higher distribution coefficient for various cations

in comparison with others. Furthermore, t

exchanger shows a greater selectivity for Th(I

Ba(II) and low absorption for Mg(II) and Ni(I

absorption of cations follows the order T

Ba(II)4Mo(VI)4Cr(VI)4Ca(II)4Ni(II)4Mg(

Some of the factors which affect the distr

coefficient of cations are the charge, size, sw

formation of complexes, nature of the chemica

Cerium molybdate shows a great difference in the

its distribution coefficient for the ions being inve

therefore numerous separation of analytical and c

interest for example, that of Th(IV) from Ba(II), M

Cr(VI); Ba(II) from Ca(II), Ni(II), Mg(II); Ca(I

Ni(II) and Mg(II); Cr(VI) fromMo(VI), Ni(II), Ca

Mg(II) can be performed on the columns

exchanger. Figs. 8–10 show some of the separation

have actually been carried out in this work.

In order to investigate the radiation stability of

molybdate; sample 1 obtained by mixing ce

molybdate in 1:2 ratio was irradiated. The ion e

capacities of irradiated sample at 50 and 200k

found to be 2.67 and 2.27meq/g, respectively, w

much lower than the value obtained for unir

sample.

Tables 7 and 8 show the distribution coeffi

various cations, using irradiated cerium molybd

exchangers at 50 and 200 kGy. The results show

irradiated samples of the ion exchanger hav

distribution coefficient values for various cations

in comparison with unirradiated sample. It

observed that the absorption of cations ha

following sequence: Th(IV)4Ba(II)4Mo(V

(VI)4Ca(II)4Ni(II)4Mg(II), which is the s

ns,

ns,

the one observed for the ion exchanger before gamma

ceri

be

owa

lues

t can

hig

absorption of 99Mo in acidic media in comparison with

tion of

the pH

4. Conclusion

ptimum

aracter-

studies

to have

a Ce/

ts little

spectra

towards

the ion

s found

g ratio

rder to

lly, the

the ion

cations.

such as

xcellent

ractical

nuclear

References

national

, vol. 17,

irconium

ation of

himii 53,

ARTICLE IN PRESS

Table 7

Distribution coefficient values of various cations using ir

diated cerium molybdate ion exchanger at 50 kGy

Cations Kd (mL/g)

Mg(II) 0.9

Ca(II) 16.5

Ba(II) 2189.2

Ni(II) 7.3

Cr(VI) 47.2

Mo(VI) 64.7

Th(IV) 7125.3

Table 8

Distribution coefficient values of various cations using ir

diated cerium molybdate ion exchanger at 200 kGy

Cations Kd (mL

Mg(II) 0.3

Ca(II) 9.4

Ba(II) 1418.3

Ni(II) 6.3

Cr(VI) 36.5

Mo(VI) 58.4

Th(IV) 6650.2

Table 9

The absorption of 99Mo on cerium molybdate in different

media

Concentration of solution (M) pH Kd

0.001 HCl 3.0 1641.2

0.01 HCl 2.0 1335.3

0.1 HCl 1.0 1293.0

0.5 HCl 0.3 789.5

Distilled water 7.0 1267.7

0.001 NaOH 11.0 1196.6

0.01 NaOH 12.0 806.0

0.1 NaOH 13.0 539.0

0.5 NaOH 13.7 523.5

0

1

2

3

4

5

6

7

0 20 40 60 80 100Volume of effluent (mL)

Rel

ativ

e im

puls

es

(a) (b)

Fig. 10. Elution curve of separation of Ba(II)–Ca(II): (a)

deionised water, 0.1mL/min; (b) 0.5M HCl, 0.4mL/min; 2.5 g

of cerium molybdate.

A. Nilchi et al. / Radiation Physics and Chemistry 75 (2006) 301–308 307

irradiation. It is worth noting that although

molybdate exhibits little change in its sorption

viour on irradiation, it still shows good stability t

radiation damage.

Table 9 shows the distribution coefficient va99Mo on cerium molybdate in different media. I

seen from the results that cerium molybdate has a

basic ones. It can be concluded that the absorp99Mo on cerium molybdate directly depends on

of the solutions.

ra-

Cerium (IV) molybdate prepared under the o

conditions of concentration and acidity was ch

ized on the basis of chemical analysis, thermal

and infrared spectra and has been demonstrated

the formula Ce(OH)2(HMoO4)2?H2O, having

Mo ratio of 0.44. Cerium molybdate exhibi

change in its sorption behaviour and infrared

after gamma irradiation; it is relatively resistant

heat, and it is chemically stable. Furthermore,

exchange capacity of cerium (IV) molybdate wa

to directly depend on the pH of solution. Mixin

has little effect on the exchange capacity.

Although further investigations are needed in o

understand the ion exchange mechanism more fu

results obtained here give a fairly good idea of

exchange behaviour towards several inorganic

The very high selectivity toward certain cations

Th(IV), Ba(II), Cr(VI) and Mo(VI), and e

absorption of 99Mo, increases the possible p

applications of cerium (IV) molybdate in

industries.

ra-

/g)

um

ha-

rds

of

be

her

Amphlett, C.B., 1985. Proceedings of the Second Inter

Conference Peaceful Uses Atomic Energy, Geneva

p. 28.

Chekomova, L.F., Cherednichenko, N.V., 1998. Z

phosphate as an ion exchanger for the separ

samarium and neodymium. Zh. Analiticheskoj K

1032.

Clearfield, A., Nancollas, G.H., Blessing, R.H., 1973. In:

anic

n, vo

natio

, vol.

., 19

appl

able

., 20

m ph

Nilchi, A., Khanchi, A., Ghanadi Maragheh, M., 2002. The

s cation

applica-

heri, A.,

naturally

against

7.

ajzadeh,

proper-

sphates.

ey, New

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Dekker, New York.

Gal, I.J., Gal, O.S., 1985. Proceedings of Second Inter

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p. 28.

Nilchi, A., Ghanadi Maragheh, M., Khanchi, A

Properties, ion exchange behaviour and analytical

tion of cerium phosphate cation exchangers suit

column use. Sep. Sci. Technol. 34, 1833–1843.

Nilchi, A., Ghanadi Maragheh, M., Khanchi, A

Characteristics of novel types of substituted ceriu

phates. J. Radioanal. Nucl. Chem. 245, 589–594.

Ion

l. 5.

nal

24,

99.

ica-

for

00.

os-

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