Nd_{2}O_{3} 첨가가 0.3CaTiO_{3}0.7(Li_{1/2}Nb_{1/2})TiO_{3} 세라믹스의 마이크로파 유전특성에 미치는 영향 
김범수^{}, 박일환^{}, 윤상옥^{1}, 김경용^{2} 
^{ }고려대학교 재료공학과 ^{1}강릉대학교 세라믹공학과 ^{2}한국과학기술연구원 세라믹공정연구센터 
Influence of Nd_{2}O_{3} Addition to 0.3CaTiO_{3}0.7(Li_{1/2}Nb_{1/2})TiO_{3} on their Microwave Dielectric Properties 





ABSTRACT 
The effects of $Nd_2O_3$ addition to $Q{cdot}f_{0}(GHz)$ ceramics with ${varepsilon}_r$ of 126, $Q{cdot}f_{0}(GHz)$ of 2240 and of $68;ppm/^{circ}C$ on their microwave properties were investigated. For the addition of 5 wt% $Nd_2O_3$, the dielectric constant (${varepsilon}_r$) showed maximum value of 131, then decreased with the further addition of $Nd_2O_3$. $Q{cdot}f_{0}(GHz)$ value was still increased to 3533 with 9 wt% $Nd_2O_3$ addition, it is influenced by densification of grain boundary. With more addition of $Nd_2O_3$ up to 18 wt%, the abnormal grain growth have influence on the decreasing of $Q{cdot}f_{0}(GHz)$ value. But with the further addition of $Nd_2O_3$ over 25 wt%, the $Q{cdot}f_{0}(GHz)$ value was again increased by the effect of the second phase ($Nd_2Ti_2O_7$) forming. The temperature coefficient of resonant frequency (${tau}_f$) was decreased from $+;68;ppm/^{circ}C$ with the addition of $Nd_2O_3$, reached $0;ppm/^{circ}C$ at 12 wt% addition, and became negative with the further addition of $Nd_2O_3$. The optimum microwave dielectric properties were obtained for $0.3CaTiO_30.7(Li_{1/2}Nd_{1/2})TiO_3$ with 9 wt% $Nd_2O_3$ sintered at $1425^{circ}C$ for 3 hrs. The dielectric constant (${varepsilon}_r$), the $Q{cdot}f_{0}(GHz)$ value, and the temperature coefficient of resonant frequency (${tau}_f$) were 108, 3533, and $+;6;ppm/^{circ}C$, respectively. 
Key words:
$CaTiO_3(Li_{1/2}Nb_{1/2})TiO_3$ ceramic, $Nd_2O_3$, Microwave, Dielectric properties 
