Research Article Synthesis, Characterization, and Thermal …downloads.hindawi.com/archive/2013/359514.pdf · 2019. 7. 31. · Rare earth phosphates belong to the family of rare earth

Hindawi Publishing CorporationJournal of MaterialsVolume 2013 Article ID 359514 8 pageshttpdxdoiorg1011552013359514

Research ArticleSynthesis Characterization and Thermal Decomposition ofPure and Dysprosium Doped Yttrium Phosphate System

K K Bamzai Nidhi Kachroo Vishal Singh and Seema Verma

Crystal Growth and Material Research Laboratory Department of Physics amp Electronics University of Jammu Jammu 180006 India

Correspondence should be addressed to K K Bamzai kkbamzyahoocom

Received 30 December 2012 Revised 21 March 2013 Accepted 21 March 2013

Academic Editor Rodrigo Martins

Copyright copy 2013 K K Bamzai et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Yttrium phosphate and dysprosium doped yttrium phosphate were synthesized from aqueous solutions using rare earth chloridephosphoric acid and traces of ammonium hydroxide The synthesized material was then characterized for their structuralinvestigations using powder X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) supplemented with energydispersive X-ray analysis (EDAX) The spectroscopic investigations were carried out using Fourier transform infrared (FTIR)spectroscopy The thermal stability was studied using differential thermogravimetric analysis (DTA) thermogravimetric analysis(TGA) and differential scanning calorimetry (DSC) techniques X-ray diffraction analysis reveals that both yttrium phosphateand dysprosium doped yttrium phosphate belong to tetragonal system with lattice parameter 119886 = 119887 = 68832 A c = 60208A and 119886 = 119887 = 69987 A 119888 = 60142 A respectively The stoichiometry of the grown composition was established by energydispersive X-ray analysis The EDAX analysis suggests the presence of water molecules The presence of water molecules alongwith orthophosphate group and metallic ion group was confirmed by FTIR analysis Thermogravimetric analysis suggests thatdecomposition in case of yttrium phosphate takes place in three different stages and the final product stabilizes after 706∘C whereasin case of dysprosium doped yttrium phosphate the decomposition occurs in two different stages and the final product stabilizesafter 519∘C

1 Introduction

Rare earth phosphates belong to the family of rare earthzircons The crystal of rare earth phosphate crystallizes intotetragonal zircon structure The general formula for rareearth zircon is RXO

4 where ldquoRrdquo = rare earth and ldquoXrdquo = P

V or As Here each ldquoXrdquo atom is surrounded by an oxygentetrahedron and each rare earth atom surrounded by eightnearest neighbor oxygen atoms [1] The rare earth ions(R3+) and phosphorous (P5+) ions occupy sites of tetragonalsymmetry There are four molecules per unit cell Rare earthphosphates find their place in wide variety of applicationssuch as optical materials including lasers [2] phosphors[3] and more recently as anti-UV materials [4] Rare earthorthophosphates exhibit certain properties that make themof interest as scintillators for gamma-ray detection [5ndash7] asthermophosphors for remote measurement of temperatureon moving components [8] and as rare earth analyticalstandards [9] Rare earth codoping in inorganic materials

has a long held transition of facilitating highly desirableoptoelectronic properties for their potential applications tothe laser industry Rare earth compounds were extensivelyapplied in luminescent and display such as lighting fieldemission display (FED) cathode ray tubes (CRT) and plasmadisplay panel (PDP) [10ndash12]

Amorphous rare earth phosphates were synthesized byprecipitation method [13] Guo et al [14] had reportedthe sol-gel synthesis of RePO

4(Re = La Ce Nd Eu Y)

Synthesis of rare earth phosphates by wet precipitationmethod has been reported by different research groups [15ndash17] Nedelec et al [18] reported the dependence of opticalproperties on the synthesis of YPO

4 whereas the thermal

decomposition of RePO4sdot 119899H2O (Re = La Ce Y) was

reported by Lucas et al [19] Several other authors reportedthe synthesis of rare earth phosphate compounds by differ-ent methods such as high temperature solid state reactiontechnique wet chemical precipitation technique and sol-geland hydrothermal synthesis [20ndash24] The physicochemical

2 Journal of Materials

properties of the material which depends on the synthesisroute that is chemical composition grain size morphologyand the crystalline structure influence the thermal behaviorthe end product and therefore their final physicochemicalproperties So these factors are of prime importance in themanufacturing processes There is no study concerning pureand doped yttriumphosphate through the influence synthesisparameters on the characteristics of the resulting materialThis paper therefore deals with study of yttrium phosphateand dysprosium doped yttrium phosphate grown by an aque-ous solution method using constituent material like yttriumchloride dysprosium chloride phosphoric acid and tracesof ammonium hydroxide To the best of authorrsquos knowledgeno such detailed work on the synthesis by this methodcharacterization and thermal behavior was reported

2 Materials and Methods

21 Materials Preparation Yttrium phosphate (YPO4) here-

after abbreviated as (YP) was grown by reacting phosphoricacid (H

3PO4) with rare earth chlorides (RCl

3 R = Y) using

ammonia solution (NH4OH) to adjust the pH The chemical

used in the present study are yttrium chloride (YCl3) and

dysprosium chloride (DyCl3) (Indian Rare Earth Ltd 99)

phosphoric acid (H3PO4) and ammonia solution (NH

4OH)

(AR grade from SDFine Chemicals) Many researchers havegiven this technique the name of precipitation method [25]or sol-gel synthesis [14] However it is worth noticeable thatin all the reported works the synthesized material was latersintered at high temperatures to obtain the crystalline formwhereas in the present work no such sintering or heatingof the material was done In case of YP the material wasobtained in the form of crystals at the room temperaturewhereas in case of dysprosium doped yttrium phosphateinstead of crystals floral shaped growth it was obtained overthe condensed gel

An aqueous solution of 05M of yttrium chloride wasmixed with an aqueous solution of 05M of phosphoric acidin the ratio of 1 5 Then ammonia solution was added tothe mixture drop by drop until a pH of 3 was obtainedamid continuous stirring The solution was then put intothe crystallizing dish then kept undisturbed in the constanttemperature bath at ambient temperature (35ndash40∘C) Aftertwo weeks the solvent was evaporated from the crystallizingdish condensed gel was obtained and cracks were seen on thesurface of condensed gel after a few days and then small sizecrystals appeared After the period of 30 days crystals weretaken out and washed under running water The chemicalreaction that took place in the previous process is as follows

YCl3+ H3PO4+ NH

4OH

997888rarr YPO4+ 3HCl + NH

3+ H2O

(1)

The preparation of 2 dysprosium doped yttrium phos-phate (Dy

002Y098

PO4) here after abbreviated as (DyYP) was

also based on the same procedure The solution of yttriumand dysprosium was made in such a way that the only tracesof dysprosium nearly 2 appear in the material An aque-ous solution of 05M of yttrium chloride and dysprosium

chloride was mixed with an aqueous solution of 05M ofphosphoric acid in the ratio of 1 5 Then ammonia solutionwas added to the mixture drop by drop until a pH of 3was obtained amid continuous stirring The solution wasthen kept undisturbed in the constant temperature bath atambient temperature (35∘ndash40∘C) During the period of 40days the material in the crystallizer condensed into a gel-likesubstance and became hard and after few days the gel brokeinto pieces and small flower-like growth appeared over eachpiece of the condensed gel The chemical reaction that tookplace in the previous process is as follows

Dy002

Y098

Cl3+ H3PO4+ NH

4OH

997888rarr Dy002

Y098

PO4+ 3HCl + NH

3+ H2O

(2)

22 Characterization The characterization techniques con-sisted of X-ray diffraction (XRD) scanning electron mi-croscopy (SEM) supplemented with energy dispersive X-ray analysis (EDAX) Fourier transform infrared spec-troscopy (FTIR) thermogravimetry (TGA) differential ther-mogravimetry (DTA) and differential scanning calorime-try (DSC) Powder X-ray diffraction was performed usingRich Seifert powder X-ray diffractometer (model ISO DebyeFlux 2002) Scanning electron microscope model number-JSM6100 supplemented with energy dispersive X-ray analysiswas used to study morphology and elemental compositionof the grown crystals To study the presence of phosphateand other groups in the crystals Fourier transform infrared(FTIR) spectrum was obtained on Perkin-Elmer 781 spec-trophotometer in the regions from 400 to 4000 cmminus1 usingKBr pellet TGA and DTA curves were recorded simulta-neously on the thermal analyzer (Shimadzu make DTG-60)over the temperature range from 25 to 1000∘C at the heatingrate of 10∘Cmin in the N

2atmosphere at a flow rate of

30mLmin

3 Results and Discussion

31 Optical Microscopy Optical microscopy was involved forrapid scanning of the grown crystals Photomicrograph ofYP and DyYP is shown in Figures 1(a) and 1(b) respectivelyYttrium phosphate appears transparent as well as platelet innature whereas DyYP shows clear view of the flower-likearrangement

32 Scanning Electron Microscopy (SEM) Electron micros-copy is a powerful tool to investigate the microstructure ofsingle crystal Figure 2 shows the SEM image of YP crystalFrom the image it is clear that it is a platelet-like crystal withclear and smooth surfaces However DyYP grew in the formof floral growth over the condensed gel These floral growthswere then scanned to have a closer look on themorphology ofthematerial Figure 3 gives a clear picture of the SEM image ofDyYP From the image it is seen that the material has grownin such a way that there are striations all over the grownarea Striations are caused by a crystal alternating betweencrystal faces as it grows Striations are generally classified aspositive and negative types Striations parallel to the crystal

Journal of Materials 3

(a) (b)

Figure 1 Photomicrograph as seen under optical microscope for (a) yttrium phosphate crystals (b) dysprosium doped yttrium phosphate

20102006 20 25 A 1 mm

Figure 2 Scanning electron micrograph of pure YP crystal whichclearly shows the platelet morphology of the crystal

faces are called positive striations and those perpendicularsto the growth faces are called negative striations [26] Inthe present case since the striations were parallel to thegrowth surface they are suggested to be positive striationsTemperature fluctuations are often regarded as the root causeof all types of striations [27]

33 X-Ray Diffraction Analysis (XRD) Figure 4(a) showsthe XRD graph of YP crystal The graph consists of highresolved peaks at some specific 2120579 Braggrsquos angles depictingthe crystalline nature of the material The data was comparedwith JCPDS data number 84ndash0335 which suggest that crystalbelongs to tetragonal systemThe cell parameters were foundto be 119886 = 119887 = 68832 A 119888 = 60208 A The unit cell volumeas calculated by WINPLOTR software comes out to be 2853cubic A Figure 4(b) shows the diffraction pattern of theDyYP crystal From the graph it is clear that like YP DyYPalso has a well-versed crystallinity The lattice parameters forDyYP comes out to be 119886 = 119887 = 69987 A 119888 = 60142 A Theunit cell volume came out to be 2946 cubic A

34 Energy Dispersive X-Ray Analysis (EDAX) To study theelemental composition of YP and DyYP qualitative and

10120583m

Figure 3 Scanning electron micrograph of floral part of DyYPrevealed certain kind of striations at the surface of the grownmaterial

quantitative analysis were performed by energy dispersive X-ray analysis The spectrum obtained from EDAX analyses isshown in Figures 5(a) and 5(b) EDAX pattern shows peakscorresponding to all the major elements present in the growncrystals as should be expected from YP system The spectracorresponding to doped DyYP shows peaks correspondingto all the major elements that is yttrium phosphorous andoxygen along with dysprosiumby suggesting that Dy hasentered into the lattice of YP system However along withthese elements some trace impurities in the form of chlorineand nitrogen were observed The experimental and theoreti-cal calculated atomic and weight percentages of elements inYP and DyYP is given in Tables 1(a) and 1(b) respectivelyFor YP crystals the theoretical values were calculated as perthe formula YPO

4sdotH2O whereas for DyYP system the values

were calculated as per the formula Dy002

Y098

PO4sdot2H2O

However it is important to mention here that EDAX analysisdoes not give experimental values of atomic and weightpercentage for lighter elements like hydrogen Therefore in

4 Journal of MaterialsC

ount

ss

2120579 (∘)

10 20 30 40 50 60 70 800

20

40

60

80

100

120

220

111

110 003 210

006 421323 403

420

211

(a)

Cou

nts

2120579 (∘)

0

10

20

30

40

50

60

10 20 30 40 50 60 70 80

220

111

010001

402

404410

005

203

(b)

Figure 4 XRD diffractograms which clearly depict the presence of crystallinity in the material along with indexing of all the prominentpeaks for (a) yttrium phosphate (YP) (b) dysprosium doped yttrium phosphate (DyYP)

Energy (keV)0 2 4 6 8 10 12 14 16 18

0

81

163

245

326

408

YK

K

K

K KYCIK

CIKP

O

N

(a)

Energy (keV)0 2 4 6 8 10 12 14 16 18

0

169

339

509

679

849

DyLDyL

YK

K

K

K KYCIK

CIK

P

O

N

(b)

Figure 5 EDAX spectra showing the presence of suggested elements along with some impurity elements for (a) Yttrium phosphate (YP) (b)Dysprosium doped yttrium phosphate (DyYP)

4000 3500 3000 2500 2000 1500 1000 500

(cmminus1)

154

9951

119879(

)

(a)

4000 3500 3000 2500 2000 1500 1000 500

(cmminus1)

154

9951

119879(

)

(b)

Figure 6 FT-IR spectra depicting the various functional groups present in (a) yttrium phosphate (YPO4

) (b) dysprosium doped yttriumphosphate (DyYPO

4

)


0 200 400 600 800 10005

6

7

8

9

10TG

A (m

g) 0

DTA

(uV

)

StartEndWeight loss

DTATGA

minus100

minus5078mgminus51123

Temperature (∘C)

19995∘C25969∘C

30128∘C

2605∘C99683∘C

(a)

0 200 400 600 800 10004

6

8

10

12

TGA

(mg)

DTATGA

50

0

DTA

(uV

)

minus100

minus50

StartEndWeight loss minus3218mg

minus33396

Temperature (∘C)

24248∘C

7488∘C

3174∘C99975∘C

(b)

Figure 7 (a)Thermographdepicting simultaneous recording of TGAandDTAcurveswhich clearly shows that pureYPO4

crystal is thermallyunstable as the temperature increases from room temperature to higher values (b) Thermograph of DyYPO

4

depicting the TGA and DTAcurves shows that it is thermally more stable as compared to the pure crystals of YPO

4

the table theoretical values of the lighter element (H) basedon the formula have been given and it is found that theexperimental and theoretical values are in close agreementwith each other within the experimental error The presenceof H2Omolecules in YP and DyYP was further confirmed by

FTIR and thermoanalytical analysis

35 Fourier Transform Infrared Spectroscopy (FT-IR) Theinfrared spectrum is formed as a consequence of the absorp-tion of electromagnetic radiation at frequencies that correlatewith the vibration of specific sets of chemical bonds froma molecule Thus the vibrational spectrum of a moleculeis considered to be a unique physical property and is char-acteristic of the molecule Figures 6(a) and 6(b) shows theFTIR spectrum for YP and DyYP respectively On analyzingthe spectrum it was observed that grown crystals showthe presence of water molecules orthophosphate group andmetallic ions group For the water vibration in addition tothe wide bands associated with different types of OH groupsextending from 38294 to 24242 in case of YP and from38294 to 23819 in case of DyYP the presence of two bandsat 16316 1596 in YP and 16314 15951 in DyYP is indicativeof the characteristics of coordinated water molecule [19] thatis the hydrated water molecule in the as-synthesized sampleare chemically bonded to the rare earth ions [28 29] Thebands from orthophosphate functional group were observedat 10749 10709 10075 and 9336 cmminus1 in both the caseswith the difference that for doped yttrium phosphate thevalues of transmittance decreases which can be attributedto the doping effect [30 31] The band around this wavenumberwas attributed to the symmetric stretchingmode (]

4)

and asymmetric stretching mode (]3) of PO

4tetrahedron

[32 33] The bands at 6307 6272 5426 and 5312 cmminus1show the presence of metallic ions Tables 2(a) and 2(b) givecomplete information about the type of functional groupspresent in YP and DyYP along with their frequency bandsand transmittance percentage

36 Thermal Decomposition Thermogravimetric analysisis a technique to assess the stability of various substances

Table 1 Experimental and theoretical calculated compositionobtained from energy dispersive X-ray analysis (EDAX) of variousconstituent elements present in the following cases

(a) Yttrium phosphate (YPO4)

Element Experimental values Theoretical valuesWt At Wt At

Oxygen 3292 5634 308 5542Phosphorous 1108 1203 1195 1108Yttrium 3315 0923 3431 1108Hydrogen mdash mdash 2294 2242

(b) Dysprosium doped yttrium phosphate (DyYPO4)


Oxygen 4012 6807 4215 7089Phosphorous 1129 1219 1360 1182Dysprosium 0113 0068 0143 0024Yttrium 3840 1010 3826 1158Hydrogen mdash mdash 456 547

Figures 7(a) and 7(b) show the simultaneously recordedthermogravimetric analysis (TGA) and differential thermo-gravimetric analysis (DTA) curve for YP and DyYP crystalThermograms were first analyzed to obtain informationabout the percentage mass loss at different temperatures andhence about the thermal stability and kinetics of dissociationof crystals YP and DyYP when heated at a uniform rate of10∘Cmin mass was found to lose continuously as a functionof temperature applied For YP starts to decompose at 39∘Cand the decomposition went up to 706∘C in three differentstages However in case of DyYP the decomposition starts at43∘C and the thermal stability was acquired by the materialat 519∘C in two different stages During these temperatureranges the mass loss was 509 and 326 for YP andDyYP respectivelyTherefore the mechanism involved in thedecomposition of the constituentmaterial is different for pure


Table 2 Presence of various functional groups along with their fre-quency bands and transmittance percentage for the following


Assignments ofbandspeaks IR bands (cmminus1) Transmittance

percentage ()10709 10

PO4 10075 189336 20

OH 38294 6031426 2

Metallic ion 6272 305426 60



percentage ()

PO410749 510075 10

OH 38294 6031426 5


and doped one Our group has earlier reported [34 35] thegrowth and thermal kinetics of pure and cadmium-dopedbariumcalcium phosphate single crystal

From Figure 7(a) YP system is thermally stable up to atemperature of 39∘C and thereafter starts decomposing Thewhole process of decomposition completes in three stepsThefirst stage of decomposition begins from 39∘C and continuesup to a temperature of 176∘C resulting in a weight loss of79 of the total weight First step of decomposition involvesconversion of hydrated YP crystal into anhydrous in natureThe second stage of decomposition starts from 176∘C andends at a temperature of 437∘C leading to weight loss of37 This weight loss in the second stage of decompositioncorresponds to the conversion of anhydrous YPO

4to Y2O3

The third stage of decomposition starts from 437∘C and goesup to 706∘C resulting in weight loss of 6 during whichthe intermediate product Y

2O3decomposes to form YO

with the release of half a molecule of oxygen as the finalproduct This type of fractional release of oxygen moleculehas also been reported earlier by Brown [36] during thethermal decomposition of inorganic solids Table 3(a) givesthe compiled summary of the decomposition process ofYPO4sdotH2O It can be seen that the calculated weight loss is

in close proximity with the observed values Based on thesethermal analyses we confirm that the grown crystal is havinga composition of YPO

4sdotH2O

From the thermogram of DyYP (Figure 7(b)) it is clearthat the doped crystal is thermally stable up to temperature of43∘Cwhichmeans that doped crystal ismore stable than pureone In case of DyYP the decomposition takes place in twosteps In the first step from 43 to 176∘C two water molecules

attached to the doped system get decomposed In the secondstage of the decomposition doped orthophosphate reducesto pyrophosphate with the release of phosphorous oxide andoxygen Table 3(b) gives detailed summary of the decompo-sition of Dy

002Y098

PO4sdot2H2O along with observed as well

as calculated weight losses In this case the calculated andobservedweight losses are in close agreementwith each otherIt is worth mentioning here that the temperature for theformation of stable product after decomposition in case ofpure one is 706∘C whereas in case of doped one the stableproduct is formed at a temperature of 519∘CThis means thatthe temperature for the formation of end product decreaseswith dysprosium substitution

The thermal decomposition of YPO4into yttrium oxide

through different stages has been accomplished with therelease ofH

2OP2O5andO

2 whereas for dopedDyYPO

4the

decomposition was accompanied by the release of H2O PO

3

and O2 Corresponding to each stage of decomposition there

are endothermic and exothermic peaks in the DTA curveAs seen from DTA curve in case of YP (Figure 7(a)) andDyYP (Figure 7(b)) there is well-marked endothermic andexothermic peak corresponding to each stage of decomposi-tion Since peaks in DTA curve correspond to weight loss inTGA curve thereby suggesting that some changes takes placein the material because of the weight loss in the material

From the thermal analysis of the system we can thereforeconfirm that product formed in the pure form that is yttriumphosphate is associated with one water molecules havingcomposition YPO

4sdotH2O whereas the doped one that is

dysprosium doped yttrium phosphate is associated with twowater molecules having composition Dy

002Y098

PO4sdot2H2O

These compositions were further supported by other analyseslike energy dispersive X-ray analysis (EDAX) and Fouriertransform infrared (FTIR) spectroscopy

4 Conclusions

From the research work carried out over the synthesis andcharacterization of the pure and dysprosium doped yttriumphosphate the following conclusions can be drawn

(1) Pure yttriumphosphatewith compositionYPO4sdotH2O

is obtained in the form of platelet like crystalswhereas the dysprosium doped yttrium phosphatehaving compositionDy

002Y098

PO4sdot2H2O is obtained

in the form of floral growth on the condensed gel(2) Yttrium phosphate and dysprosium doped yttrium

phosphate belong to tetragonal system The latticeparameters obtained in case of YP are 119886 = 119887 =68832 A 119888 = 60208 A Similarly the lattice param-eters in case of doped one that is DyYP come out tobe 119886 = 119887 = 69987 A 119888 = 60142 A Thus the crystalstructure of yttrium phosphate remains unaffected bymodification of its composition by dysprosium

(3) Scanning electron microscopy (SEM) studies give aclear picture about the morphology of the growncrystals The qualitative and quantitative elementalanalyses employing EDAX technique confirm the


Table 3 Results of thermal decomposition for different temperature ranges with observed and calculated weight loss in the following cases

(a) Yttrium phosphate (YP)

Stage Temperature (∘C) Decomposition steps Weight loss ()Observed Calculated

First 39ndash176 YPO4 sdotH2O rarr YPO4 + H2O 79 89Second 176ndash437 2[YPO4] rarr Y2O3 + P2O5(g) 37 387Third 437ndash706 Y2O3 rarr YO + 05O2(g) 6 7

(b) Dysprosium doped yttrium phosphate (DyYP)


First 43ndash176 Dy002Y098PO4sdot2H2O rarr Dy002Y098PO4 + 2H2O 1365 1628Second 176ndash519 3[Dy002Y098PO4] rarr (Dy002Y098)2P2O7 + PO3(g) + O2 1904 1995

presence of major elements in the grown materialThe stoichiometric composition of the grown systemas established by EDAX technique is YPO

4sdotH2O and

Dy002

Y098

PO4sdot2H2O

(4) Fourier transformed infrared studies on YP andDyYP confirm the presence of water moleculesorthophosphate functional group and metallic iongroup The frequency bands within the range of38294 to 24242 cmminus1 are attributed to the presenceof water molecules The effect of doping can be seenclearly in FTIR spectrum where the transmittancepercentage decreases in case of DyYP

(5) The thermal studies carried out on YP and DyYPreveal that pure yttrium phosphate is less stable ascompared to doped yttrium phosphate YPO

4starts

to decompose early and becomes stable at a later stagein comparison to its doped counterpart

(6) The thermal decomposition of YP into the finalstable product of yttrium monoxide underwent threedifferent stages with the release of H

2O P2O5 and

O2whereas for DyYP the decomposition was accom-

panied by the release of H2O PO

3 and O

2 and a

final product of doped yttrium pyrophosphate wasobtained

References

[1] Z A Kazei N P Kolmakova and O A Shishkina ldquoMagnetoe-lastic contribution to thermal expansion of rare-earth zirconsrdquoPhysics B vol 245 no 2 pp 164ndash172 1998

[2] V Mehta G Aka A L Dawarb and A Mansingh ldquoOpticalproperties and spectroscopic parameters of Nd3+-doped phos-phate and borate glassesrdquo Optical Materials vol 12 pp 53ndash631999

[3] K Riwotzki H Meyssamy A Kornowski and M HaaseldquoLiquid-phase synthesis of doped nanoparticles colloids ofluminescing LaPO

4

Eu and CePO4

Tb particles with a narrowparticle size distributionrdquo Journal of Physical Chemistry B vol104 no 13 pp 2824ndash2828 2000

[4] N Imanaka T Masui H Hirai and G Y Adachi ldquoAmorphouscerium-titanium solid solution phosphate as a novel family of

band gap tunable sunscreen materialsrdquo Chemistry of Materialsvol 15 no 12 pp 2289ndash2291 2003

[5] W W Moses M J Weber S E Derenzno D Perry P Berdahland L A Boatnor ldquoProspects for dense infrared emittingscintillatorsrdquo IEEE Transactions on Nuclear Science vol 45 pp462ndash466 1998

[6] A J Wojtowicz D Wisniewski A Lempicki and L A Boat-ner ldquoScintillation mechanisms in rare earth orthophosphatesrdquoRadiation Effects and Defects in Solids vol 135 no 1 pp 305ndash310 1995

[7] A Lempicki E Berman A J Wojtowicz M Balcerzyk and LA Boatner ldquoCerium-doped orthophosphates new promisingscintillatorsrdquo IEEE Transactions on Nuclear Science vol 40 no4 pp 384ndash387 1993

[8] S W Allison L A Boatner and G T Gillies ldquoCharacterizationof high-temperature thermographic phosphors spectral prop-erties of LuPO

4

Dy(1)Eu(2)rdquo Applied Optics vol 25 pp5624ndash5627 1995

[9] E Jarosewich and L A Boatner ldquoRare-earth element refer-ence samples for electron microprobe analysisrdquo GeostandardsNewsletter vol 15 pp 397ndash399 1991

[10] J Dhanaraj R Jagannathan T R N Kutty and C H LuldquoPhotoluminescence characteristics of Y

2

O3

Eu3+ nanophos-phors prepared using sol-gel thermolysisrdquo Journal of PhysicalChemistry B vol 105 no 45 pp 11098ndash11105 2001

[11] Z Wei L Sun C Liao C Yan and S Huang ldquoFluorescenceintensity and color purity improvement in nanosized YBO

3

EurdquoApplied Physics Letters vol 80 no 8 pp 1447ndash1449 2002

[12] R S Meltzer S P Feofilov B Tissue and H B Yuan ldquoDepen-dence of fluorescence lifetimes of Y

2

O3

Eu3+ nanoparticles onthe surrounding mediumrdquo Physical Review B vol 60 no 20pp R14012ndashR14015 1999

[13] H Hirai T Masui N Imanaka and G Y Adachi ldquoChar-acterization and thermal behavior of amorphous rare earthphosphatesrdquo Journal of Alloys and Compounds vol 374 no 1-2 pp 84ndash88 2004

[14] Y Guo PWoznicki A Barkatt E E Saad and I G Talmy ldquoSol-gel synthesis of microcrystalline rare earth orthophosphatesrdquoJournal of Materials Research vol 11 no 3 pp 639ndash649 1996

[15] D Bregiroux S Lucas E Champion F Audubert and DBernache-Assollant ldquoSintering andmicrostructure of rare earthphosphate ceramics REPO

4

with 119877119864 = La Ce or Yrdquo Journal ofthe European Ceramic Society vol 26 no 3 pp 279ndash287 2006


[16] J Zhu W D Cheng D S Wu et al ldquoCrystal and bandstructures and optical characterizations of sodium rare earthphosphates NaLnP

2

2O7

and NaLn(PO3

)4

(Ln = Ce Eu)rdquoJournal of Alloys and Compounds vol 454 no 1-2 pp 419ndash4262008

[17] H Lai A Bao Y Yang et al ldquoUV luminescence property ofYPO4

RE (RE = Ce3+ Tb3+)rdquo Journal of Physical Chemistry Cvol 112 no 1 pp 282ndash286 2008

[18] J M Nedelec D Avignant and R Mahiou ldquoSoft chemistryroutes to YPO

4

-based phosphors dependence of textural andoptical properties on synthesis pathwaysrdquo Chemistry of Materi-als vol 14 no 2 pp 651ndash655 2002

[19] S Lucas E Champion D Bernache-Assollant and G LeroyldquoRare earth phosphate powders RePO

4

sdotnH2

O (Re=La Ce or Y)II Thermal behaviorrdquo Journal of Solid State Chemistry vol 177no 4-5 pp 1312ndash1320 2004

[20] R S Fugelson ldquoSynthesis and single-crystal growth of rare-earth orthophosphatesrdquo Journal of the American Ceramic Soci-ety vol 47 pp 257ndash258 1964

[21] N N Chudinova L P Shklover andGM Balagina ldquoReactionsof lanthanum oxide with phosphoric acids at 100ndash500∘CrdquoInorganic Materials vol 11 pp 590ndash593 1975

[22] N Arul-Dhas and K C Patel ldquoSynthesis of A1PO4

LaPO4

and KTiOPO4

by flash combustionrdquo Journal of Alloys andCompounds vol 202 pp 137ndash141 1993

[23] H Onoda H Nariani H Maki and I Motooka ldquoMe-chanochemical effects on synthesis of Rhabdophane-typeneodymium and cerium phosphatesrdquo Materials Chemistry andPhysics vol 78 pp 400ndash404 2002

[24] O Terra N Dacheux R Podar and N Clavier ldquoPreparationand characterization of lanthanum-gadolinium monazites asceramics for radioactive waste storagerdquo New Journal of Chem-istry vol 27 pp 957ndash967 2003

[25] S V Ushakov K B Helean A Navrotsky and L A BoatnerldquoThermochemistry of rare-earth orthophosphatesrdquo Journal ofMaterials Research vol 16 no 9 pp 2623ndash2633 2001

[26] Y Endo and I Sunagawa ldquoPositive and negative striations inpyriterdquo American Mineralogist vol 58 pp 930ndash935 1973

[27] B Cockayne and M P Gates ldquoGrowth striations in verticallypulled oxide and fluoride single crystalsrdquo Journal of MaterialsScience vol 2 pp 118ndash123 1967

[28] W Di X X Zhao S Lu X Wang and H Zhao ldquoThermaland photoluminescence properties of hydrated YPO

4

Eu3+nanowiresrdquo Journal of Solid State Chemistry vol 180 pp 2478ndash2484 2007

[29] L Qiong S Yiguo Y H Sheng and H Wei ldquoYPO4

nanocrys-tals preparation and size-induced lattice symmetry enhance-mentrdquo Journal of Rare Earths vol 26 no 4 pp 495ndash500 2008

[30] S Lucas E Champion C Penot G Leroy and D Bernache-Assollant ldquoSynthesis and characterization of rare earth phos-phate powdersrdquoKey EngineeringMaterials vol 206ndash213 pp 47ndash50 2001

[31] A Hezel and S D Ross ldquoForbidden transitions in the infra-red spectra of tetrahedral anions-III Spectra-structure correla-tions in perchlorates sulphates and phosphates of the formulaMXO

4

rdquo Spectrochimica Acta vol 22 pp 1949ndash1961 1966[32] D K Breitinger G Brehm J Mohr et al ldquoVibrational spectra

of synthetic crandallite-type mineralsmdashoptical and inelasticneutron scattering spectrardquo Journal of Raman Spectroscopy vol37 no 1-3 pp 208ndash216 2006

[33] M J Bushiri R S Jayasree M Fakhfakh and V U NayarldquoRaman and infrared spectral analysis of thallium niobyl phos-phates Tl

2

NbO2

PO4

Tl3

NaNb4

O9

(PO4

)2

and TlNbOP2

O7

rdquoMaterials Chemistry and Physics vol 73 pp 179ndash185 2002

[34] S Suri K K Bamzai and V Singh ldquoGrowth and thermalkinetics of pure and cadmium doped barium phosphate singlecrystalrdquo Journal of Thermal Analysis and Calorimetry vol 105no 1 pp 229ndash238 2011

[35] K K Bamzai S Suri and V Singh ldquoSynthesis characterizationthermal and dielectric properties of pure and cadmium dopedcalcium hydrogen phosphaterdquoMaterials Chemistry and Physicsvol 135 pp 158ndash167 2012

[36] M E Brown ldquoQuantitative thermoanalytical studies of thekinetics and mechanisms of the thermal decomposition ofinorganic solidsrdquo Thermochimica Acta vol 110 pp 153ndash1581987

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


properties of the material which depends on the synthesisroute that is chemical composition grain size morphologyand the crystalline structure influence the thermal behaviorthe end product and therefore their final physicochemicalproperties So these factors are of prime importance in themanufacturing processes There is no study concerning pureand doped yttriumphosphate through the influence synthesisparameters on the characteristics of the resulting materialThis paper therefore deals with study of yttrium phosphateand dysprosium doped yttrium phosphate grown by an aque-ous solution method using constituent material like yttriumchloride dysprosium chloride phosphoric acid and tracesof ammonium hydroxide To the best of authorrsquos knowledgeno such detailed work on the synthesis by this methodcharacterization and thermal behavior was reported

2 Materials and Methods

21 Materials Preparation Yttrium phosphate (YPO4) here-

after abbreviated as (YP) was grown by reacting phosphoricacid (H

3PO4) with rare earth chlorides (RCl

3 R = Y) using

ammonia solution (NH4OH) to adjust the pH The chemical

used in the present study are yttrium chloride (YCl3) and

dysprosium chloride (DyCl3) (Indian Rare Earth Ltd 99)

phosphoric acid (H3PO4) and ammonia solution (NH

4OH)

(AR grade from SDFine Chemicals) Many researchers havegiven this technique the name of precipitation method [25]or sol-gel synthesis [14] However it is worth noticeable thatin all the reported works the synthesized material was latersintered at high temperatures to obtain the crystalline formwhereas in the present work no such sintering or heatingof the material was done In case of YP the material wasobtained in the form of crystals at the room temperaturewhereas in case of dysprosium doped yttrium phosphateinstead of crystals floral shaped growth it was obtained overthe condensed gel

An aqueous solution of 05M of yttrium chloride wasmixed with an aqueous solution of 05M of phosphoric acidin the ratio of 1 5 Then ammonia solution was added tothe mixture drop by drop until a pH of 3 was obtainedamid continuous stirring The solution was then put intothe crystallizing dish then kept undisturbed in the constanttemperature bath at ambient temperature (35ndash40∘C) Aftertwo weeks the solvent was evaporated from the crystallizingdish condensed gel was obtained and cracks were seen on thesurface of condensed gel after a few days and then small sizecrystals appeared After the period of 30 days crystals weretaken out and washed under running water The chemicalreaction that took place in the previous process is as follows

YCl3+ H3PO4+ NH

4OH

997888rarr YPO4+ 3HCl + NH

3+ H2O

(1)

The preparation of 2 dysprosium doped yttrium phos-phate (Dy

002Y098

PO4) here after abbreviated as (DyYP) was

also based on the same procedure The solution of yttriumand dysprosium was made in such a way that the only tracesof dysprosium nearly 2 appear in the material An aque-ous solution of 05M of yttrium chloride and dysprosium

chloride was mixed with an aqueous solution of 05M ofphosphoric acid in the ratio of 1 5 Then ammonia solutionwas added to the mixture drop by drop until a pH of 3was obtained amid continuous stirring The solution wasthen kept undisturbed in the constant temperature bath atambient temperature (35∘ndash40∘C) During the period of 40days the material in the crystallizer condensed into a gel-likesubstance and became hard and after few days the gel brokeinto pieces and small flower-like growth appeared over eachpiece of the condensed gel The chemical reaction that tookplace in the previous process is as follows

Dy002

Y098

Cl3+ H3PO4+ NH

4OH

997888rarr Dy002

Y098

PO4+ 3HCl + NH

3+ H2O

(2)

22 Characterization The characterization techniques con-sisted of X-ray diffraction (XRD) scanning electron mi-croscopy (SEM) supplemented with energy dispersive X-ray analysis (EDAX) Fourier transform infrared spec-troscopy (FTIR) thermogravimetry (TGA) differential ther-mogravimetry (DTA) and differential scanning calorime-try (DSC) Powder X-ray diffraction was performed usingRich Seifert powder X-ray diffractometer (model ISO DebyeFlux 2002) Scanning electron microscope model number-JSM6100 supplemented with energy dispersive X-ray analysiswas used to study morphology and elemental compositionof the grown crystals To study the presence of phosphateand other groups in the crystals Fourier transform infrared(FTIR) spectrum was obtained on Perkin-Elmer 781 spec-trophotometer in the regions from 400 to 4000 cmminus1 usingKBr pellet TGA and DTA curves were recorded simulta-neously on the thermal analyzer (Shimadzu make DTG-60)over the temperature range from 25 to 1000∘C at the heatingrate of 10∘Cmin in the N

2atmosphere at a flow rate of

30mLmin

3 Results and Discussion

31 Optical Microscopy Optical microscopy was involved forrapid scanning of the grown crystals Photomicrograph ofYP and DyYP is shown in Figures 1(a) and 1(b) respectivelyYttrium phosphate appears transparent as well as platelet innature whereas DyYP shows clear view of the flower-likearrangement

32 Scanning Electron Microscopy (SEM) Electron micros-copy is a powerful tool to investigate the microstructure ofsingle crystal Figure 2 shows the SEM image of YP crystalFrom the image it is clear that it is a platelet-like crystal withclear and smooth surfaces However DyYP grew in the formof floral growth over the condensed gel These floral growthswere then scanned to have a closer look on themorphology ofthematerial Figure 3 gives a clear picture of the SEM image ofDyYP From the image it is seen that the material has grownin such a way that there are striations all over the grownarea Striations are caused by a crystal alternating betweencrystal faces as it grows Striations are generally classified aspositive and negative types Striations parallel to the crystal


(a) (b)


20102006 20 25 A 1 mm





10120583m





Y098

PO4sdot2H2O



ount

ss

2120579 (∘)

10 20 30 40 50 60 70 800

20

40

60

80

100

120

220

111

110 003 210

006 421323 403

420

211

(a)

Cou

nts

2120579 (∘)

0

10

20

30

40

50

60

10 20 30 40 50 60 70 80

220

111

010001

402

404410

005

203

(b)


Energy (keV)0 2 4 6 8 10 12 14 16 18

0

81

163

245

326

408

YK

K

K

K KYCIK

CIKP

O

N

(a)

Energy (keV)0 2 4 6 8 10 12 14 16 18

0

169

339

509

679

849

DyLDyL

YK

K

K

K KYCIK

CIK

P

O

N

(b)


4000 3500 3000 2500 2000 1500 1000 500

(cmminus1)

154

9951

119879(

)

(a)

4000 3500 3000 2500 2000 1500 1000 500

(cmminus1)

154

9951

119879(

)

(b)



4

)


0 200 400 600 800 10005

6

7

8

9

10TG

A (m

g) 0

DTA

(uV

)

StartEndWeight loss

DTATGA

minus100


Temperature (∘C)

19995∘C25969∘C

30128∘C

2605∘C99683∘C

(a)

0 200 400 600 800 10004

6

8

10

12

TGA

(mg)

DTATGA

50

0

DTA

(uV

)

minus100

minus50


minus33396

Temperature (∘C)

24248∘C

7488∘C

3174∘C99975∘C

(b)



4


4




4)


4tetrahedron
















PO4 10075 189336 20

OH 38294 6031426 2




percentage ()

PO410749 510075 10

OH 38294 6031426 5




4to Y2O3





4sdotH2O



002Y098





2OP2O5andO


4the


3






002Y098

PO4sdot2H2O


4 Conclusions




002Y098














4sdotH2O and

Dy002

Y098

PO4sdot2H2O



4starts



2O P2O5 and



3 and O

2 and a


References




4

Eu and CePO4








4




2

O3



3



2

O3





4




2

2O7

and NaLn(PO3

)4





4



4

sdotnH2





LaPO4

and KTiOPO4








4






4




2

NbO2

PO4

Tl3

NaNb4

O9

(PO4

)2

and TlNbOP2

O7












CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a) (b)


20102006 20 25 A 1 mm





10120583m





Y098

PO4sdot2H2O



ount

ss

2120579 (∘)

10 20 30 40 50 60 70 800

20

40

60

80

100

120

220

111

110 003 210

006 421323 403

420

211

(a)

Cou

nts

2120579 (∘)

0

10

20

30

40

50

60

10 20 30 40 50 60 70 80

220

111

010001

402

404410

005

203

(b)


Energy (keV)0 2 4 6 8 10 12 14 16 18

0

81

163

245

326

408

YK

K

K

K KYCIK

CIKP

O

N

(a)

Energy (keV)0 2 4 6 8 10 12 14 16 18

0

169

339

509

679

849

DyLDyL

YK

K

K

K KYCIK

CIK

P

O

N

(b)


4000 3500 3000 2500 2000 1500 1000 500

(cmminus1)

154

9951

119879(

)

(a)

4000 3500 3000 2500 2000 1500 1000 500

(cmminus1)

154

9951

119879(

)

(b)



4

)


0 200 400 600 800 10005

6

7

8

9

10TG

A (m

g) 0

DTA

(uV

)

StartEndWeight loss

DTATGA

minus100


Temperature (∘C)

19995∘C25969∘C

30128∘C

2605∘C99683∘C

(a)

0 200 400 600 800 10004

6

8

10

12

TGA

(mg)

DTATGA

50

0

DTA

(uV

)

minus100

minus50


minus33396

Temperature (∘C)

24248∘C

7488∘C

3174∘C99975∘C

(b)



4


4




4)


4tetrahedron
















PO4 10075 189336 20

OH 38294 6031426 2




percentage ()

PO410749 510075 10

OH 38294 6031426 5




4to Y2O3





4sdotH2O



002Y098





2OP2O5andO


4the


3






002Y098

PO4sdot2H2O


4 Conclusions




002Y098














4sdotH2O and

Dy002

Y098

PO4sdot2H2O



4starts



2O P2O5 and



3 and O

2 and a


References




4

Eu and CePO4








4




2

O3



3



2

O3





4




2

2O7

and NaLn(PO3

)4





4



4

sdotnH2





LaPO4

and KTiOPO4








4






4




2

NbO2

PO4

Tl3

NaNb4

O9

(PO4

)2

and TlNbOP2

O7












CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




ount

ss

2120579 (∘)

10 20 30 40 50 60 70 800

20

40

60

80

100

120

220

111

110 003 210

006 421323 403

420

211

(a)

Cou

nts

2120579 (∘)

0

10

20

30

40

50

60

10 20 30 40 50 60 70 80

220

111

010001

402

404410

005

203

(b)


Energy (keV)0 2 4 6 8 10 12 14 16 18

0

81

163

245

326

408

YK

K

K

K KYCIK

CIKP

O

N

(a)

Energy (keV)0 2 4 6 8 10 12 14 16 18

0

169

339

509

679

849

DyLDyL

YK

K

K

K KYCIK

CIK

P

O

N

(b)


4000 3500 3000 2500 2000 1500 1000 500

(cmminus1)

154

9951

119879(

)

(a)

4000 3500 3000 2500 2000 1500 1000 500

(cmminus1)

154

9951

119879(

)

(b)



4

)


0 200 400 600 800 10005

6

7

8

9

10TG

A (m

g) 0

DTA

(uV

)

StartEndWeight loss

DTATGA

minus100


Temperature (∘C)

19995∘C25969∘C

30128∘C

2605∘C99683∘C

(a)

0 200 400 600 800 10004

6

8

10

12

TGA

(mg)

DTATGA

50

0

DTA

(uV

)

minus100

minus50


minus33396

Temperature (∘C)

24248∘C

7488∘C

3174∘C99975∘C

(b)



4


4




4)


4tetrahedron
















PO4 10075 189336 20

OH 38294 6031426 2




percentage ()

PO410749 510075 10

OH 38294 6031426 5




4to Y2O3





4sdotH2O



002Y098





2OP2O5andO


4the


3






002Y098

PO4sdot2H2O


4 Conclusions




002Y098














4sdotH2O and

Dy002

Y098

PO4sdot2H2O



4starts



2O P2O5 and



3 and O

2 and a


References




4

Eu and CePO4








4




2

O3



3



2

O3





4




2

2O7

and NaLn(PO3

)4





4



4

sdotnH2





LaPO4

and KTiOPO4








4






4




2

NbO2

PO4

Tl3

NaNb4

O9

(PO4

)2

and TlNbOP2

O7












CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0 200 400 600 800 10005

6

7

8

9

10TG

A (m

g) 0

DTA

(uV

)

StartEndWeight loss

DTATGA

minus100


Temperature (∘C)

19995∘C25969∘C

30128∘C

2605∘C99683∘C

(a)

0 200 400 600 800 10004

6

8

10

12

TGA

(mg)

DTATGA

50

0

DTA

(uV

)

minus100

minus50


minus33396

Temperature (∘C)

24248∘C

7488∘C

3174∘C99975∘C

(b)



4


4




4)


4tetrahedron
















PO4 10075 189336 20

OH 38294 6031426 2




percentage ()

PO410749 510075 10

OH 38294 6031426 5




4to Y2O3





4sdotH2O



002Y098





2OP2O5andO


4the


3






002Y098

PO4sdot2H2O


4 Conclusions




002Y098














4sdotH2O and

Dy002

Y098

PO4sdot2H2O



4starts



2O P2O5 and



3 and O

2 and a


References




4

Eu and CePO4








4




2

O3



3



2

O3





4




2

2O7

and NaLn(PO3

)4





4



4

sdotnH2





LaPO4

and KTiOPO4








4






4




2

NbO2

PO4

Tl3

NaNb4

O9

(PO4

)2

and TlNbOP2

O7












CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials








PO4 10075 189336 20

OH 38294 6031426 2




percentage ()

PO410749 510075 10

OH 38294 6031426 5




4to Y2O3





4sdotH2O



002Y098





2OP2O5andO


4the


3






002Y098

PO4sdot2H2O


4 Conclusions




002Y098














4sdotH2O and

Dy002

Y098

PO4sdot2H2O



4starts



2O P2O5 and



3 and O

2 and a


References




4

Eu and CePO4








4




2

O3



3



2

O3





4




2

2O7

and NaLn(PO3

)4





4



4

sdotnH2





LaPO4

and KTiOPO4








4






4




2

NbO2

PO4

Tl3

NaNb4

O9

(PO4

)2

and TlNbOP2

O7












CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials












4sdotH2O and

Dy002

Y098

PO4sdot2H2O



4starts



2O P2O5 and



3 and O

2 and a


References




4

Eu and CePO4








4




2

O3



3



2

O3





4




2

2O7

and NaLn(PO3

)4





4



4

sdotnH2





LaPO4

and KTiOPO4








4






4




2

NbO2

PO4

Tl3

NaNb4

O9

(PO4

)2

and TlNbOP2

O7












CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





2

2O7

and NaLn(PO3

)4





4



4

sdotnH2





LaPO4

and KTiOPO4








4






4




2

NbO2

PO4

Tl3

NaNb4

O9

(PO4

)2

and TlNbOP2

O7












CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Documents

Research Article Synthesis, Characterization, and Thermal …downloads.hindawi.com/archive/2013/359514.pdf · 2019. 7. 31. · Rare earth phosphates belong to the family of rare earth