Abstract The Jahn–Teller effect in Nd 1 – x A x MnO 3 manganites (A = Ba, Sr; x = 0.15, 0.25) was studied by high-temperature X-ray diffraction and differential scanning calorimetry. The bond lengths and angles of the MnO 6 octahedron characterizing the Jahn–Teller distortion were first determined for these compositions by the Rietveld method. It was found that the temperature of removal of this distortion was markedly lower than that for the undoped compound. The temperature dependences of the electrical conductivity of all the above samples were measured for the first time. The highest electrical conductivity was found for Nd 0.75 Sr 0.25 MnO 3 . A decrease in the strontium concentration to 15 mol % decreased the electrical conductivity by almost half. Replacing strontium with barium also decreased the electrical conductivity, which was especially noticeable at low temperatures. The effective activation energy of electrical conductivity was characteristic of the polaron charge transfer mechanism.

中文翻译：

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Nd1 – xAxMnO3 固体溶液 (A = Ba, Sr) 中的掺杂浓度对 20–1200°C 温度范围内的电导率和结构转变的影响

摘要 通过高温 X 射线衍射和差示扫描量热法研究了 Nd 1 – x A x MnO 3 锰酸盐 (A = Ba, Sr; x = 0.15, 0.25) 中的 Jahn-Teller 效应。表征 Jahn-Teller 畸变的 MnO 6 八面体的键长和角度首先通过 Rietveld 方法确定。发现消除这种变形的温度明显低于未掺杂化合物的温度。首次测量了所有上述样品的电导率的温度依赖性。Nd 0.75 Sr 0.25 MnO 3 的电导率最高。锶浓度降低到 15 mol% 时，电导率几乎降低了一半。用钡代替锶也降低了电导率，这在低温下尤为明显。导电的有效活化能是极化子电荷转移机制的特征。