Qiang Liangsheng

FT-RAMAN SPECTROSCOPIC STUDY OF Pb1−x Ca x TiO3 NANOCRYSTALS

FT-Raman Spectra of Pb1−x Ca x TiO3 nanocrystals with different lanthanum amounts were measured at 288 K and 378 K. Several nanocrystals of Pb0.85Ca0.15TiO3 with different grain size were also prepared at 288 K. The effects of the amount of lanthanum, grain size and temperature on phonon frequency were discussed in details. Furthermore, the conclusion that lattice expansions presentation in PCT nanocrystals can be obtained by the frequency comparison of PCT nanocrystal of x ≥ 0.2 with ceramic doped with the same amount of calcium.

Preparation of ferroelectric lead titanate ceramics by a modified sol-gel method

Abstract The usual sol-gel method for the preparation of nanocrystalline lead titanate has been improved in this research. The hydrolytic process of lead acetate [Pb(Ac)2] and titanium butoxide [Ti(O(CH2)3CH3)4] sol precursor was promoted by the addition of methyl alcohol (CH3OH) solution containing a certain amount of water. The fresh gel was directly sintered to transform the gel into PbTiO3 polycrystals, which were quite easily ground into fine powders for ceramics pellets. The modified sol-gel method has reduced the preparation period from a few days to several hours. X-ray diffraction and electrical measurements have indicated that the PbTiO3 thus obtained exhibits the same structure as that derived from ordinary sol-gel method and shows excellent dielectric and ferroelectric properties