Optical and structral properties of pure and Ce-doped nanocrystals of barium titanate

✍ Scribed by Ming-Sheng Zhang; Jian Yu; Wan-chun Chen; Zhen Yin

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 412 KB
• Volume: 40
• Category: Article
• ISSN: 0960-8974
• DOI: 10.1016/s0960-8974(00)00021-8

✦ Synopsis

Nanocrystals barium titanate (nc-BT) and Ce-doped barium titanate were synthesized by an unusual hydrothermal process. X-ray diffraction mad Raman spectroscopy were used to investigate their microstructures, as well as their lattice vibration and photoluminescence (PL) spectra. Particle sizes as small as 20 nm were measured by X-ray diffraction pattern via Scherer equation. The critical size relative to the cubic-tetragonal transition is about 48 nm in nc-BT below which ferroelectricity vanishes. The lattice parameter ratio c/a of is equal to 1.003, much smaller than 1.01 for that of the bulk crystal, leading to a weakening of ferroelectricity. Hydroxyl defects are observed in the Ce-doped nc-BT samples which show a vibrational band at 3300 cm 1. Good crystallization character and the lattice perfection were characterized by Ranaan spectra in the nanophase barium titanate. Strong PL spectra centered at 696 and 585 um were observed in the pure and Ce-doped nc-BT, respectively. PL dependence on temperature and annealing time was examined. A molecule-like recombination and the charge transfer between Ce 4+ and Ce 3÷ are proposed to elucidate tke luminescence process in the nc-BT and Ce-doped nc-BT system.