Effect of La3+ and Nd3+ on the microwave dielectric properties of (Pb0.5Ca0.5)(Fe0.5Nb0.5)O3 ceramics

Microwave dielectric properties of A-site substitution by both La3+ and Nd3+ in (Pb0.5Ca0.5)(Fe0.5Nb0.5)O3 system were investigated. Microwave dielectric properties of A-site charge unbalance substitution of [(Pb0.5Ca0.5)1−x(La0.5Nd0.5)x](Fe0.5Nb0.5)O3+δ (PCLNFN) were improved because the solid solution of small amount of surplus (La, Nd)3+ with (Pb, Ca)2+ could eliminate oxygen vacancies; the formation of secondary phase (pyrochlore phase) was also caused by surplus (La, Nd)3+. The decreasing of dielectric constant with the increase of (La, Nd)3+ content was due to the formation of pyrochlore phase. Qf values were almost unchanged at x=0.02–0.08, but the temperature coefficient of resonant frequency (TCF) was decreased. Typically, at x=0.06, the excellent microwave dielectric properties of Qf=5822 GHz, εr=99.9 with TCF=0 ppm/°C were obtained.