Microwave dielectric properties of (PbCa)(FeNb)O3 ceramics with A site Nd3+ substitution

Abstract The influence of Nd3+ A site charge unbalanced substitution on the microwave properties and crystal structure of (Pb0.48Ca0.52)(Fe0.5Nb0.5 )O3 ceramics has been investigated. For Nd3+ content x ≤ 2 mol-%, specimens can be produced with a single phase of perovskite structure. Other specimens with Nd3+ content x > 2 mol-% possessed PbO–Nb2O5 pyrochlore phase, with linearly increasing content with increasing x. Permittivity first increased and then gradually decreased as Nd3+ content increased to 20 mol-%. The unloaded quality factor Qf reached a maximum of 5210 GHz when Nd3+ content reached 5 mol-%. At higher Nd3+ content, the relative content of pyrochlore phase began to exceed 14.5%, and Qf degenerated. The temperature coefficient of resonant frequencies could be effectively controlled from 37.8 to 0.9 ppm K-1. A small value of 7.8 ppm K-1 was obtained in the [(Pb0.48Ca0.52)1-x Ndx](Fe0.5Nb0.5)O3 system when x = 0.05 and the permittivity and Qf value were 87.9 and 5210 GHz respectively. The relationship between microwave dielectric properties and crystal structure is also discussed.