Abstract The wide band-gap of iron titanium oxide Fe2TiO5 (Pseudobrookite) is very well known as potential thermoelectric compounds for its great Seebeck coefficient. In this article, the thermoelectric, magnetic, electronic, and structural properties of ferrous pseudobrookite Fe2-xTi1+xO5 (x = 0, 0.5, and 1.0) compounds were calculated by first principle calculations. The electronic structures were computed using the plane-wave pseudopotential method within the GGA-PBE approximation considering the Hubbard-U exchange-correlation. The considered electronic structure in the GGA + U scheme displays that two alloys are semiconductors with an indirect energy gap of 1.75 and 0.61 eV, respectively, for Fe2TiO5, and Fe1·5Ti1·5O5 and metallic for FeTi2O5 compounds. The thermoelectric properties were estimated using the semi-classical Boltzmann theory and the rigid band method in the temperature range of 50–800 K. The carrier concentration (n,p), electrical conductivity (σ), Seebeck coefficient (S), electronic thermal conductivity (κ) and the electric figure of merit (ZT) as a function of temperature were obtained for Fe2-xTi1+xO5 (x = 0, 0.5, and 1.0) compounds. Also, the thermoelectric properties versus chemical potential were studied at three constant temperatures. The Seebeck coefficient decreased with increasing temperature. The peak value of S is 1913 μVK−1, 1217 μVK−1, and 616 μVK−1 for Fe2TiO5, Fe1·5Ti1·5O5, and FeTi2O5, respectively. By increasing the chemical potential and moving it to the conduction electrons, the thermal conductivity increased. The results show that n-type Fe2TiO5 and p-type Fe1·5Ti1·5O5 at 300 K can reach the ZT values of 1.21 and 0.98, respectively. These results detected that n-type Fe2TiO5 compounds are potential thermoelectric material at room temperature.

中文翻译：

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假板钛矿型 Fe2-xTi1+xO5（x = 0、0.5 和 1）化合物的结构、电子、磁和热电特性：DFT + U 方法

摘要 铁钛氧化物 Fe2TiO5（伪板钛矿）的宽带隙因其巨大的塞贝克系数而成为众所周知的潜在热电化合物。在本文中，亚铁拟板钛矿 Fe2-xTi1+xO5（x = 0、0.5 和 1.0）化合物的热电、磁、电子和结构特性是通过第一原理计算得到的。考虑到 Hubbard-U 交换相关性，在 GGA-PBE 近似中使用平面波赝势方法计算电子结构。GGA + U 方案中考虑的电子结构表明，两种合金是半导体，对于 Fe2TiO5 和 Fe1·5Ti1·5O5 的间接能隙分别为 1.75 和 0.61 eV，对于 FeTi2O5 化合物为金属。在 50-800 K 的温度范围内，使用半经典 Boltzmann 理论和刚带方法估计热电特性。 载流子浓度 (n,p)、电导率 (σ)、塞贝克系数 (S)、电子热Fe2-xTi1+xO5（x = 0、0.5 和 1.0）化合物的电导率 (κ) 和电品质因数 (ZT) 作为温度的函数。此外，在三个恒定温度下研究了热电特性与化学势的关系。塞贝克系数随温度升高而降低。对于 Fe2TiO5、Fe1·5Ti1·5O5 和 FeTi2O5，S 的峰值分别为 1913 μVK-1、1217 μVK-1 和 616 μVK-1。通过增加化学势并将其移动到传导电子，热导率增加。结果表明，n型Fe2TiO5和p型Fe1·5Ti1·5O5在300 K时的ZT值分别达到1.21和0.98。这些结果检测到n型Fe2TiO5化合物在室温下是潜在的热电材料。