Oxygen vacancy distribution has a direct effect on the crystal structure and physical properties of complex oxides, resulting in versatile applications. Here, we report on a reversible topotactic phase transition between the perovskite and brownmillerite structures for the LaCoO 3− δ ( δ = 0–0.5) epitaxial film by annealing the sample under different conditions. In the atmosphere of 2 × 10 −4 Pa, LaCoO 3 film is transformed from the perovskite structure to the brownmillerite structure when annealing temperature exceeds 500 °C. Meanwhile, the magnetic order transits from ferromagnetic to anti-ferromagnetic. Variable-range hopping demonstrates the electronic transport process for both phases. The incorporation of oxygen vacancies results in an upward shift of the ln ρ - T −1/4 curve, without affecting the ln ρ - T −1/4 slope. We found signatures for preferential distribution for oxygen vacan...

中文翻译：

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外延LaCoO 3−δ膜的钙钛矿相和褐镁钙石相之间的定势跃迁及其结果

氧空位分布直接影响复杂氧化物的晶体结构和物理性质，从而产生了广泛的应用。在这里，我们通过在不同条件下对样品进行退火，报道了LaCoO 3−δ（δ= 0–0.5）外延膜的钙钛矿结构和褐铁矿结构之间的可逆全平面相变。在2×10 -4 Pa的气氛中，当退火温度超过500℃时，LaCoO 3膜从钙钛矿结构转变为褐铁矿结构。同时，磁阶从铁磁转变为反铁磁。可变范围跳变演示了两个阶段的电子传输过程。氧空位的结合导致lnρ-T -1/4曲线向上移动，而不影响lnρ-T -1/4斜率。