Abstract Structural, magnetic and transport measurements were performed on La0.7Sr0.3Mn1-xCrxO3 (0≤x≤0.15) perovskite-like manganites in order to study the effect of the substitution on the Mn-site on the magnetotransport properties. All samples are found to be of single phase. The structural parameters obtained by using Rietveld refinement of X-ray diffraction data show that all samples crystallize with rhombohedral perovskite-type symmetry with R 3 ¯ c space group. The concentration dependence of the unit cell parameters indicates that chromium (or most of the chromium) has a trivalent state. The magnetization and electric measurements reveal that all the samples demonstrate a ferromagnetic to paramagnetic transition and a metallic to semiconductor one with increasing temperature. The Curie temperature TC and the resistivity transition temperature Tms shift to lower values with increasing Cr content. The correct expression for bandwidth W∼ TC is given. The temperature dependence of electrical resistivity supports the small polaron hopping model and variable range hopping conduction model above the metal–semiconductor transition temperature (Tms). The calculated hopping distance and hopping energy increased as rate of Cr content increased whereas density of states at Fermi level decreased.

中文翻译：

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Cr掺杂对类钙钛矿锰酸盐结构磁性和输运性能的影响

摘要 对La0.7Sr0.3Mn1-xCrxO3 (0≤x≤0.15)类钙钛矿型锰酸盐进行了结构、磁性和输运测量，以研究Mn位点取代对磁输运性能的影响。发现所有样品都是单相的。通过使用 X 射线衍射数据的 Rietveld 精修获得的结构参数表明，所有样品结晶为菱形钙钛矿型对称，具有 R 3 ¯ c 空间群。晶胞参数的浓度依赖性表明铬（或大部分铬）具有三价态。磁化和电测量表明，随着温度的升高，所有样品都表现出铁磁到顺磁的转变以及金属到半导体的转变。随着 Cr 含量的增加，居里温度 TC 和电阻率转变温度 Tms 移至较低值。给出了带宽 W∼TC 的正确表达式。电阻率的温度依赖性支持金属-半导体转变温度 (Tms) 以上的小极化子跳跃模型和可变范围跳跃传导模型。计算出的跳跃距离和跳跃能量随着 Cr 含量率的增加而增加，而费米能级的态密度降低。