Papers by Author: Ji Xia Lei

Abstract: Precursors of calcium strontium zirconate (Ca0.8Sr0.2ZrO3) were synthesized by oxalate coprecipitation method. TG-DTA was used to characterize the thermal decomposition behaviors of the precursors. The XRD results revealed that the powders crystallized as cubic Ca0.8Sr0.2ZrO3 with increasing heating temperature up to 1000°C. Calcium strontium zirconate ceramics were obtained under conventional sintering conditions by using the as-prepared Ca0.8Sr0.2ZrO3 powders. The SEM micrographs of the ceramics sintered at 1450oC exhibited narrow grain-size distribution with the average grain size around 0.7 4m. The dielectric properties showed that, dielectric constant of the Ca0.8Sr0.2ZrO3 was about 24.0 and dielectric loss was 0.002 at the frequency of 1GHz and the room temperature.

Abstract: Nano-sized barium titanate powders were prepared by the high-gravity reactive precipitation (HGRP)-hydrothermal method. The properties and defects of hydrothermal barium titanate crystallites were investigated by TEM, XRD and FTIR. The mean particle size of the hydrothermal barium titanate was about 70 nm with narrow particle size distribution. The crystallite phases and OH defects were focused. The results show that the powders without heat treatment were crystallized as cubic-BaTiO3 and the absence of tetragonal with increasing calcined temperature to 1100°C. The IR results exhibited the OH defect content in the crystallites was to increase the heat treatment temperature and reduced the probability of forming barium vacancies.