Sol-gel preparation of nanocrystalline CaWO4

Nanocrystalline CaWO4 has been synthesized by a sol-gel method using tungsten (VI) oxide, WO3, and calcium nitrate tetrahydrate, Ca(NO3)2 center dot 4H(2)O as starting materials. The synthesis leads to a sol-gel process when citric or tartaric acids are introduced into the Solution obtained by dissolving WO,3 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 degrees 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).