Perovskite계 La_(0.9)Sr_(0.1)(Ga_(1-x)Fe_(x))_(0.8)Mg_(0.2)O_(3- δ) 의 제조 및 특성 = Preparation and Characterization of La_(0.9)Sr_(0.1)(Ga_(1-x)Fe_(x))_(0.8)Mg_(0.2)O_(3-δ) Perovskite-type Oxides

다국어 초록 (Multilingual Abstract)

In this paper, perovskite-type La_(0.9)Sr_(0.1)(Ga_(1-X)Fe_(X))_(0.8)Mg_(0.2)O_(3-6)(x＝0-0.5) powders were prepared by solid state reaction, followed by estimation of phase structures and properties according to Fe contents and sintering conditions. Impurity phases as well as perovskite phase were observed in the powders which were calcined at 800℃ for 10h followed by sintering at 1300℃ for 10h. The smallest amount of the impunrity phases was observed in the powder with the highest Fe content. The X-ray diffraction peaks corresponding to the 220 peak in pseudo cubic lattice were collected. The data were used for calulation of orthorhombic unit cell parameters by PROFITVZ program. Mean unit cell parameters(V^(1/3)) decreased with x at the Fe contents not more than 0.2 and increased with x at the Fe contents not less than 0.3. Electrical conductivity of the bar-like samples was measured as a function of temperature from 290K up to 1200K in air by a standard two-probe technique using platinum electrodes. The relationship between lot(oT) and l/T as lkHz exhibited the Arrhenius behavior, Electrical conductivity increased with Fe contents. Particularly, Fe contents substantially contributed to electrical conductivity at lower temperature. In air, La_(0.9)Sr_(0.1)(Ga_(0.75)Fe_(0.25))_(0.8)Mg_(0.2)O_(3-6) perovskie-type oxide showed the reversible elongation property in which the structural phase transition occurred at near 600℃.