Phase evolution and enhanced dielectric properties of BaO•Nd2O3•TiO2•B2O3 glass-based dielectrics containing CaCu3Ti4O12

CaCu3Ti4O12 (CCTO) has been studied as a filler for the potential high k LTCC (low temperature co-fired ceramics) materials based on a nonconventional BaO center dot Nd2O3 center dot TiO2 center dot B2O3 glass in terms of firing temperature and CCTO content. The material system was proven to be high crystallizable as the resultant crystalline phases of BaTi(BO3)(2), BaNd2Ti5O14 and NdBO3 were observed. The relative content of the crystalline phases were strongly dependant on firing temperature and CCTO content. Interestingly, the 30 wt% CCTO sample showed early densification at 610-670 degrees C and then unexpected expansion after 850 degrees C. The 40-60 wt% CCTO samples showed the unexpected secondary densification behavior over the temperature range of 850-950 degrees C. As a promising example, a combination consisting of the glass and 40 wt% CCTO exhibited k similar to 55 and tan delta similar to 0.07, which is very rare at this low sintering temperature of 850 degrees C. These materials system were found to be chemically very stable especially in the H2SO4 acid solution. (C) 2012 Elsevier B.V. All rights reserved.