Microwave Dielectric Properties of (Pb0.4Ca0.6)[(Fe1/2Nb1/2)1-x(Mg1/3Nb2/3)x]O3Ceramics

Abstract

Microwave dielectric properties of (Pb 0.4 Ca 0.6 )[(Fe 1/2 Nb 1/2 ) 1-x (Mg 1/3 Nb 2/3 ) x ]O₃ (PCFMN) ceramics were investigated as a function of (Mg 1/3 Nb 2/3 ) 4+ content (0.1≤x≤0.8). A single perovskite phase with the cubic structure was obtained through the given composition range. The unit cell volume was increased with (Mg 1/3 Nb 2/3 ) 4+ content, due to the larger average ionic size of (Mg 1/3 Nb 2/3 ) 4+ than that of (Fe 1/2 Nb 1/2 ) 4+ for B-site ion. Dielectric constant (K) and Temperature Coefficient of Resonant Frequency(TCF) of PCFMN ceramics were dependent on (Mg 1/3 Nb 2/3 ) 4+ content due to the decrease of ionic polarizability and B-site bond valence, respectively. Qf value was decreased with (Mg 1/3 Nb 2/3 ) 4+ content due to the decrease of grain size. Typically, K of 73.56, Qf of 5,074 GHz and TCF of -6.45 ppm/℃ were obtained for the specimens with x=0.4 sintered at 1250℃ for 3 h.