Lowering of CaZrO3 sintering temperature using lithium–calcium fluoride flux addition

The effects of a lithium–calcium fluoride flux on the sintering and the low frequency dielectric properties of acceptor/donor-doped CaZrO3 ceramics were investigated. The acceptor(Mn)/donor(W) doping was used to avoid reduction of Zr in the CaZrO3 ceramics. The lithium–calcium fluoride flux was selected since liquid phase sintering lower the CaZrO3 sintering temperature. With such additions, several low-temperature mechanisms emerge and the sintering temperatures can be effectively lowered. A simple model was used to analyse these different mechanisms in terms of their origin and efficiency. The dielectric properties of CaZrO3 with flux additions are strongly dependent on the densification. CaZrO3 ceramics sintered at high temperature without any addition display a high permittivity, low losses and a good behaviour under electrical field and temperature. Using this flux, CaZrO3 can be sintered below the nickel’s melting point (1450 °C) and 92% of the theoretical density can be achieved. The dielectric properties at 1 MHz are then εr≈34 and a loss factor close to 0.1%.