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首页> 外文会议>International Conference on Solid Compounds of Transition Elements >Anomalous Thermal Behaviour of Mixed Cobaltites-Ferrites and Cobaltites-Chromites
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Anomalous Thermal Behaviour of Mixed Cobaltites-Ferrites and Cobaltites-Chromites

机译：混合钴铁素体和钴铁体-铬铁矿的异常热行为

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摘要

Series of the mixed cobaltites-ferrites RCo_(1-x)Fe_xO_3 (x = 0.1-0.9) and cobaltites-chromites RC_o_(0.5)Cr_(0.5)O_3 (R = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er) with the orthorhombic perovskite structure (space group Pbnm) have been prepared from stoichiometric amounts of rare earth oxides, C03O4, Fe_2O_3 and Q_2O_3 by solid-state reaction in air at 1473-1573 K. In situ high-temperature X-ray synchrotron powder diffraction revealed anomalous lattice expansion of both series, which is reflected in a sigmoidal dependence of the unit cell parameters and in abnormal anisotropic increase of the thermal expansion coefficients (TEC). Depending on the composition, several broad maxima in the temperature range of 500-1000 K are observed, which are evidently connected with the transitions of Co~(3+ (cations to the higher spin states. The observed anomalies in the mixed cobaltites-ferrites and cobaltites-chromites are less pronounced compared with the corresponding "pure" cobaltites.
机译：混合钴铁氧体RCo_（1-x）Fe_xO_3（x = 0.1-0.9）和钴-铬铁矿RC_o_（0.5）Cr_（0.5）O_3（R = Pr，Nd，Sm，Eu，Gd，Tb，Dy的系列）通过化学计量的稀土氧化物C03O4，Fe_2O_3和Q_2O_3在空气中（1473-1573 K）进行固相反应，制备了具有正交晶系钙钛矿结构（空间群Pbnm）的Er）。原位高温X射线同步加速器粉末衍射揭示了两个系列的异常晶格膨胀，这反映为晶胞参数的S形依存关系以及热膨胀系数（TEC）的异常各向异性增加。根据成分的不同，在500-1000 K的温度范围内观察到几个宽的最大值，这些峰明显与Co〜（3+（阳离子到更高的自旋态）的跃迁有关。在混合的钴铁素体中观察到的异常与相应的“纯”钴相比，钴和亚铬铁的含量较差。

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