Microwave Dielectric Properties of (Pb_{0.4}Ca_{0.6})[(Fe_{1/2}Nb_{1/2})_{1x}(Mg_{1/3}Nb_{2/3})_{x}]O_{3} Ceramics 
Eung Soo Kim^{}, KiMoon Han^{1}, JongHee Kim^{2}, KiHyun Yoon^{} 
^{ }Department of materials Engineering, Kyonggi University ^{1}MLCC Research Group, Samaung Electro Mechanics Co. ^{2}Department of Ceramic Engineering, Yonsei University 



ABSTRACT 
Microwave dielectric properties of (P $b_{0.4}$C $a_{0.6}$)[($Fe_{frac{1}{2}}$N $b_{frac{1}{2}}$)$_{1x}$ (M $g_{1}$ 3/N $b_{2}$ 3/)x] $O_3$ (PCFMN) ceramics were investigated as a function of (M $g_{1}$ 3/N $b_{2}$ 3/)$^{4+}$ content (0.1$leq$x$leq$0.8). A single perovskite phase with the cubic structure was obtained through the given composition range. The unit cell volume was increased with (M $g_{1}$ 3/N $b_{2}$ 3/)$^{4+}$, due to the larger average ionic size of (M $g_{1}$ 3/N $b_{2}$ 3/)$^{4+}$ than that of ($Fe_{frac{1}{2}}$N $b_{frac{1}{2}}$)$^{4+}$ for Bsite ion. Dielectric constant (K) and Temperature Coefficient of Resonant Frequency(TCF) of PCFMN ceramics were dependent on (M $g_{1}$ 3/N $b_{2}$ 3/)$^{4+}$ content due to the decrease of ionic polarizability and Bsite bond valence, respectively. Qf value was decreased with (M $g_{1}$ 3/N $b_{2}$ 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/$^{circ}C$ were obtained for the specimens with x=0.4 sintered at 125$0^{circ}C$ for 3 h.125$0^{circ}C$ for 3 h. 
Key words:
(${Pb_{0.4}}{Ca_{0.6}}$)[(${Fe_{1/2}}{Nb_{1/2}}$)$_{1x}$(${Mg_{1/3}}{Nb{2/3}}$)$_x$]$O_3$, Microwave dielectric properties, Dielectric polarization, Bsite bond valence, Rattling effect 


