The Effect of Sintering Atmosphere on the Microwave Dielectric Properties of <TEX>$(1-x)CaTiO_3-xLaAlO_3$</TEX> System

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J. Korean Ceram. Soc. > Volume 34(5); 1997 > Article

Journal of the Korean Ceramic Society 1997;34(5): 505.

소결 분위기가 $(1-x)CaTiO_3-xLaAlO_3$계의 마이크로파 유전특성에 미치는 영향

여동훈, 김현재, 문종하¹

한국과학기술연구원 세라믹스부
¹전남대학교 무기재료공학과

The Effect of Sintering Atmosphere on the Microwave Dielectric Properties of $(1-x)CaTiO_3-xLaAlO_3$ System

ABSTRACT

The effects of sintering atmospheres(air, O2, N2) on the sintering and microwave dielectric properties of (1-x)CaTiO3-xLaAlO3 system was investigated. The sintered density of (1-x)CaTiO3-xLaAlO3 under air atmosphere increased linearly with increasing x, but it decreased in the range of x>0.5 under O2 atmosphere and x>0.6 under N2 atmosphere in spite of the increament of the smaller La(1.06$AA$) and Al(0.5 $AA$) ion than Ca(0.99$AA$) and Ti(0.6$AA$). In case of the air sintering atmosphere of (1-x)CaTiO3-xLaAlO3 the two phases of orthorhombic and rhombohedral crystal system were coexisting, and the XRD peak of rhombohedral crystalsystem was to be higher with increasing x. However, the sintering atmosphere of O2 and N2 made the monophasic crystal system of orthorhombic keep up by x=0.5 and x=0.6, respectively, and it transformed to pseudo-cubic crystal system in x>0.5 and x>0.6. The XRD peak intensity of (1-x)CaTiO3-xLaAlO3 was to be gradually higher with increasing x under the air atmosphere of sintering. Whereas, its XRD peak intensity increased till x=0.6 but decreased with increasing x in the range of x>0.6 under O2 and N2 atmosphere. The relative dielectric constant of (1-x)CaTiO3-xLaAlO3 sintered under air atmosphere decreased linearly and the Q.f0 value increased according as x increased. On the other hand, the relative dielectric constant of (1-x)CaTiO3-xLaAlO3 under O2 and N2 atmosphere decreased in the range of x$leq$0.5 with increasing x, but increased rapidly in the range of x$geq$0.6. And the Q.f0 value increased till x=0.6 but decreased in the range of x>0.6 with increasing x. The temperature coefficient of resonant frequency had no relation to sintering atmosphere.

Key words: Microwave, Dielectric constant, Temperature coefficient of resonant frequency, Q