Comparative Analysis of Li2CO3 Doped (Ba,Sr)TiO3 and ZnBO Doped (Ba,Sr)TiO3 Ceramics for the Low Temperature Sintering Applications

Abstract

For the research on the LTCC(Low Temperature Co-fire Ceramic) applications, low temperature sintered ceramics have been extensively investigated. In this study, we have focused on the Li 2 CO 3 doped (Ba,Sr)TiO 3 and ZnBO doped (Ba,Sr)TiO 3 ceramics which have moderate dielectric properties such as high dielectric permittivity and low loss tangent. Until now, B 2 O 3 has been commonly employed as the low temperature sintering aid. However, in this paper, we suggest Li 2 CO 3 and ZnBO as alternative sintering aids to the B 2 O 3 . 1∼5 wt% of Li 2 CO 3 or ZnBO was added to BST ceramics in order to reduce the sintering temperature. Li 2 CO 3 doped BST and ZnBO doped BST ceramics were respectively sintered from 700°C to 1050°C and 750°C to 1250°C by 50°C to confirm the sintering temperature with different dopants concentrations. By adding Li 2 CO 3 to the BST ceramics, the sintering temperature of BST ceramics was drastically lowered down to 900°C, whereas by introducing ZnBO dopants to BST, the loss tangent was decreased. From the XRD analysis, ZnBO doped BST ceramics have no pyro phase. 3 wt% Li 2 CO 3 doped BST ceramics, which sintered at 900°C, have moderate relative dielectric permittivity of 1451 at 1 kHz, while 5 wt% ZnBO doped BST ceramics, sintered at 1100°C, have decreased dielectric permittivity of 1180 at 1 kHz. The loss tangent of ZnBO doped BST was decreased compared with that of BST. The loss tangent of ZnBO (1 wt%) doped BST was decreased down to 2.71 × 10−3 at 1 MHz.