Low sintering BaNd_2Ti_4O_(12) microwave ceramics prepared by CuO thin layer coated powder

摘要

Recently, BaO-Nd_2O_3-TiO_2 systems are widely studied for microwave applications because of their high dielectric constant and high quality factor. However, pure BaNd_2Ti_4O_(12) ceramics without additives have to be sintered above 1300 deg C to achieve densification. Copper oxide has been known as a good sintering aid for electronic ceramics and less reactive toward silver. We have introduced the CuO into BaNd_2Ti_4O_(12) by modifying the surface of BaNd_2Ti_4O_(12) by CuO thin layer on the calcined powder instead of mixing CuO directly with BaNd_2Ti_4O_(12) powder. The process reduces the amount of sintering aid and minimized the negative impact of sintering aid on dielectric properties such as quality factor. The CuO precursor solution of Cu(CH_3COO)_2, Cu(NO_3)_2 and CuSO_4, were used to prepare CuO thin layer. They were investigated individually to determine their effects on the densification, crystalline structure, microstructure and microwave dielectric properties of BaNd_2Ti_4O_(12). The CuSO_4 coated BaNd_2Ti_4O_(12) sintered at 1150 deg C has exhibited better dielectric properties than those of CuO doped BaNd_2Ti_4O_(12) (k, 62.5 versus 61.2; Q X f, 11,500 GHz versus 10,500 GHz). The thin layer dopant coating process has been found to be a very effective way to lower ceramic sintering temperature without scarifying its dielectric properties.