[PDF]    http://dx.doi.org/10.3952/lithjphys.47110

Open access article / Atviros prieigos straipsnis

Lith. J. Phys. 47, 63–68 (2007)


SOL–GEL PREPARATION OF NANOCRYSTALLINE CaWO4
A. Katelnikovasa, L. Grigorjevab, D. Millersb, V. Pankratovb, and A. Kareivaa
aFaculty of Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania
E-mail: aivaras.kareiva@chf.vu.lt
bInstitute of Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga, Latvia

Received 1 December 2006

Nanocrystalline CaWO4 has been synthesized by a sol–gel method using tungsten (VI) oxide, WO3, and calcium nitrate tetrahydrate, Ca(NO3)2·4H2O as starting materials. The synthesis leads to a sol–gel process when citric or tartaric acids are introduced into the solution obtained by dissolving WO3 in ammonia. Citric and tartaric acids have great effect on stabilizing the precursor solution. The results have shown that the single phase product was obtained when the gel was heat-treated at 800 °C. The obtained CaWO4 particles ranged from 350 to 850 nm in size and showed emission in the blue region. CaWO4 ceramics has been characterized by means of thermogravimetric and differential thermal analysis (TG/DTA), infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL).
Keywords: calcium tungstate, sol–gel, X-ray diffraction, photoluminescence
PACS: 42.70.-a, 61.46.-w, 68.37.Hk, 78.67.Bf


NANOKRISTALINIO CaWO4 SINTEZĖ ZOLIŲ IR GELIŲ METODU
A. Katelnikovasa, L. Grigorjevab, D. Millersb, V. Pankratovb, A. Kareivaa
aVilniaus universitetas, Vilnius, Lietuva
bLatvijos universiteto Kietojo kūno fizikos institutas, Ryga, Latvija

Zolių ir gelių metodu susintetintas nanokristalinis kalcio volframatas (CaWO4) (pradinėmis medžiagomis buvo WO3 ir Ca(NO3)2·4H2O). Citrinos ir vyno rūgštys buvo naudojamos kaip kompleksonai. Nustatyta, kad galutinio produkto morfologija ir gautų dalelių dydis priklauso nuo imtos rūgšties. CaWO4 dalelių dydis svyravo nuo 350 iki 850 nm. Rezultatai parodė, kad iškaitinus gelius 800 °C temperatūroje susiformavo šelito kristalinės struktūros vienfazis CaWO4, skleidžiantis mėlynos spektro srities šviesą. Susintetintas kalcio volframatas tirtas naudojant termogravimetrinės-diferencinės terminės analizės (TG/DTA), infraraudonosios spektrometrijos (IR), Rentgeno spindulių difrakcijos (XRD), skenuojančiosios elektroninės mikroskopijos (SEM) bei fotoliuminescencinės analizės (PL) metodus.


References / Nuorodos

[1] R. Manalert and M.N. Rahaman, Sol–gel processing and sintering of yttrium aluminum garnet (YAG) powders, J. Mater. Sci. 31, 3453–3458 (1996),
http://dx.doi.org/10.1007/BF00360748
[2] E. Comini, A. Toncelli, M. Tonelli, E. Zannoni, E. Cavalli, A. Speghini, and M. Bettinelli, Optical spectroscopy and fluorescence dynamics of Er3+ in Ca3Sc2Ge3O12 crystal, J. Opt. Soc. Am. B 14, 1938–1944 (1997),
http://dx.doi.org/10.1364/JOSAB.14.001938
[3] J.T. Vega-Duran, O. Barbosa-Garcia, L.A. Diaz-Torres, M.A. Meneses-Nava, and D.S. Sumida, Effects of energy back transfer on the luminescence of Yb and Er ions in YAG, Appl. Phys. Lett. 76, 2032–2034 (2000),
http://dx.doi.org/10.1063/1.126245
[4] N.V. Kuleshov, A.A. Lagatsky, A.V. Podlipensky, V.P. Mikhailov, and G. Huber, Pulsed laser operation of Yb-doped KY(WO4)2 and KGd(WO4)2, Opt. Lett. 22, 1317–1319 (1997),
http://dx.doi.org/10.1364/OL.22.001317
[5] Y. Urata, T. Fukuda, H. Ito, and S. Wada, Laser performance of neodymium-doped lanthanum tungstate crystals, Jpn. J. Appl. Phys. 40, 6453–6454 (2001),
http://dx.doi.org/10.1143/JJAP.40.6453
[6] Y. Chen, X. Lin, Z. Luo, and Y. Huang, Spectroscopic properties of Nd3+ ions in La2(WO4)3 crystal, Chem. Phys. Lett. 381, 598–604 (2003),
http://dx.doi.org/10.1016/j.cplett.2003.10.046
[7] V.N. Kolobanov, I.A. Kamenskikh, V.V. Mikhailin, I.N. Shpinkov, D.A. Spassky, B.I. Zadneprovsky, L.I. Potkin, and G. Zimmerer, Optical and luminescent properties of anisotropic tungstate crystals, Nucl. Instrum. Methods A 486, 496–503 (2002),
http://dx.doi.org/10.1016/S0168-9002(02)00760-X
[8] V. Nagirnyi, E. Feldbach, L. Jonsson, M. Kirm, A. Lushchik, C. Lushchik, L.L. Nagornaya, V.D. Ryzhikov, F. Savikhiu, G. Svensson, and I.A. Tupitsina, Excitonic and recombination processes in CaWO4 and CdWO4 scintillators under synchrotron irradiation, Radiat. Meas. 29, 247–250 (1998),
http://dx.doi.org/10.1016/S1350-4487(98)00017-1
[9] P. Mogilevsky, T.A. Parthasarathy, and M.D. Petry, Anisotropy in room temperature microhardness and fracture of CaWO4 scheelite, Acta Materialia 52, 5529–5537 (2004),
http://dx.doi.org/10.1016/j.actamat.2004.08.022
[10] D.J. Norris, D.E. Arlinghaus, L. Meng, R. Heiny, and L.E. Scriven, Opaline photonic crystals: How does self-assembly work? Adv. Mater. 16, 1393–1399 (2004),
http://dx.doi.org/10.1002/adma.200400455
[11] M. Remskar, Inorganic nanotubes, Adv. Mater. 16, 1497–1504 (2004),
http://dx.doi.org/10.1002/adma.200306428
[12] S.J. Chen, J. Li, X.T. Chen, J.M. Hong, Z. Xue, and X.Z. You, Solvothermal synthesis and characterization of crystalline CaWO4 nanoparticles, J. Cryst. Growth 253, 361–365 (2003),
http://dx.doi.org/10.1016/S0022-0248(03)01089-3
[13] L.J. Burcham and I.E. Wachs, Vibrational analysis of the two non-equivalent, tetrahedral tungstate (WO4) units in Ce2(WO4)3 and La2(WO4)3, Spectrochim. Acta A 54, 1355–1368 (1998),
http://dx.doi.org/10.1016/S1386-1425(98)00036-5
[14] R.R. Khanna and E.R. Lippincott, Infrared spectra of some scheelite structures, Spectrochim. Acta A 24, 905–908 (1968),
http://dx.doi.org/10.1016/0584-8539(68)80189-8
[15] E. Garskaite, K. Gibson, A. Leleckaite, J. Glaser, D. Niznansky, A. Kareiva, and H.-J. Meyer, On the synthesis and characterization of iron-containing garnets (Y3Fe5O12, YIG and Fe3Al5O12, IAG), Chem. Phys. 323, 204–210 (2006),
http://dx.doi.org/10.1016/j.chemphys.2005.08.055
[16] D. Chen, G. Shen, K. Tang, H. Zheng, and Y. Qian, Low-temperature synthesis of metal tungstates nanocrystallites in ethylene glycol, Mater. Res. Bull. 38, 1783–1789 (2003),
http://dx.doi.org/10.1016/j.materresbull.2003.09.004