Vijay Ammu, S Charan Prasanth, Jose Roshan, Saravanan K Venkata
Department of Physics, School of Basic and Applied Sciences, Central University of Tamil Nadu Thiruvarur 610 005 India
Department of Science and Humanities, MLR Institute of Technology Hyderabad 500 043 India.
RSC Adv. 2023 Jun 29;13(28):19651-19660. doi: 10.1039/d3ra03053a. eCollection 2023 Jun 22.
The untiring endeavour towards green energy is a trending research among the research community. Thermoelectric materials are of vital importance here owing to their emission-free operation. As a righteous candidate, calcium manganate materials are being explored to increase its figure of merit. In this study, the structural, microstructural, electrical transport, and high-temperature thermoelectric measurements of LaDyCaMnO { = 0.025 (L25D25), 0.05 (L50D50), 0.075 (L75D75), and 0.1 (L100D100)} were systematically performed. The structural confirmation of the synthesised sample was validated using X-ray diffraction, which also revealed the orthorhombic (space group: ) crystallisation of co-doped samples with no traces of secondary peaks. A significant increase in the unit cell volume was observed with rare earth substitutions. The morphological studies revealed that the prepared samples were highly dense and the grain size was reduced with rare earth concentration. The substitution of La and Dy enhanced the conductivity values of pristine CMO by two orders of magnitude due to the high concentration of charge carriers and the presence of Mn ions due to rare earth doping. The conductivity increased with rare earth concentrations but diminished for = 0.1 due to the localization of charges. The Seebeck coefficient values were negative for all the prepared samples, indicating electrons as the predominant carriers over the entire operating range. A minimum of 1.8 W m K was achieved for LaDyCaMnO and the maximum value obtained was 0.122 at 1070 K for LaDyCaMnO.
对绿色能源的不懈努力是研究界的一个热门研究方向。热电材料因其无排放运行在此至关重要。作为一个合适的候选材料，锰酸钙材料正在被探索以提高其优值。在本研究中，系统地对LaDyCaMnO { = 0.025（L25D25）、0.05（L50D50）、0.075（L75D75）和0.1（L100D100）}进行了结构、微观结构、电输运和高温热电测量。使用X射线衍射对合成样品进行结构确认，结果还显示共掺杂样品为正交晶系（空间群： ）结晶，且无二次峰痕迹。观察到随着稀土取代，晶胞体积显著增加。形态学研究表明，制备的样品高度致密，且晶粒尺寸随稀土浓度降低。由于电荷载流子浓度高以及稀土掺杂导致的Mn离子的存在，La和Dy的取代使原始CMO的电导率值提高了两个数量级。电导率随稀土浓度增加，但在 = 0.1时由于电荷局域化而降低。所有制备样品的塞贝克系数值均为负，表明在整个工作范围内电子是主要载流子。LaDyCaMnO的最小 为1.8 W m K，在1070 K时LaDyCaMnO获得的最大值 为0.122。
