Abstract In the current research work R2CoMnO6 (R = La, Sm, Gd and Dy) double perovskites (DPOs) have been synthesized using auto combustion sol-gel method. Structural characterizations were carried out by X-ray diffraction technique and the analysis confirms the correct crystal structure by Rietveld refinement with a monoclinic symmetry (space group P21/n) in all DPOs. Crystallite size has been calculated by using Scherrer and Williamson-Hall (W-H) methods and found that the crystallite size with the decrease in ionic radius (RLn) decreases from 61.37–49.03 nm on average. The IR reflectivity spectrums fitted by the Lorentz oscillator model reveal that the given DPOs have a monoclinic structure and change of R-site also has ability to impact on the crystal structure. The optical band gap has been estimated in the range of 1.30–1.60 eV reflecting that the considered DPOs have potential to be used as light harvesting materials. The resistivity data of all DPOs depict semiconductor like behavior above room temperature and this behavior has been best described by small polaron hopping (SPH) conduction mechanism. Dielectric measurements exhibit usual dielectric dispersion, which is due to the Maxwell-Wagner-type interfacial polarization in all DPOs. AC conductivity measurement also suggests the conduction is due to SPH.

中文翻译：

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A位稀土取代对双钙钛矿结构、磁性、光学和输运性能的影响

摘要 在目前的研究工作中，R2CoMnO6 (R = La、Sm、Gd 和 Dy) 双钙钛矿 (DPO) 已使用自燃溶胶-凝胶法合成。结构表征是通过 X 射线衍射技术进行的，分析通过 Rietveld 精修确认了正确的晶体结构，在所有 DPO 中均具有单斜对称性（空间群 P21/n）。使用 Scherrer 和 Williamson-Hall (WH) 方法计算了微晶尺寸，发现随着离子半径 (RLn) 的减小，微晶尺寸平均从 61.37-49.03 nm 减小。洛伦兹振子模型拟合的红外反射光谱表明，给定的 DPO 具有单斜结构，R 位的变化也对晶体结构有影响。光学带隙估计在 1.30-1 的范围内。60 eV 反映了所考虑的 DPO 具有用作光收集材料的潜力。所有 DPO 的电阻率数据都描述了室温以上类似半导体的行为，并且这种行为已通过小极化子跳跃 (SPH) 传导机制得到最好的描述。介电测量表现出通常的介电色散，这是由于所有 DPO 中的 Maxwell-Wagner 型界面极化。交流电导率测量也表明传导是由 SPH 引起的。这是由于所有 DPO 中的 Maxwell-Wagner 型界面极化。交流电导率测量也表明传导是由 SPH 引起的。这是由于所有 DPO 中的 Maxwell-Wagner 型界面极化。交流电导率测量也表明传导是由 SPH 引起的。