Joshi H, Ram M, Limbu N, Rai D P, Thapa B, Labar K, Laref A, Thapa R K, Shankar A
Condensed Matter Theory Research Lab, Kurseong College, Darjeeling, 734203, India.
Department of Physics, St. Josephs College, North Point, Darjeeling, 734103, India.
Sci Rep. 2021 Mar 23;11(1):6601. doi: 10.1038/s41598-021-86181-7.
A first-principle computational method has been used to investigate the effects of Ru dopants on the electronic and optical absorption properties of marcasite FeS. In addition, we have also revealed a new marcasite phase in RuS, unlike most studied pyrite structures. The new phase has fulfilled all the necessary criteria of structural stability and its practical existence. The transition pressure of 8 GPa drives the structural change from pyrite to orthorhombic phase in RuS. From the thermodynamical calculation, we have reported the stability of new-phase under various ranges of applied pressure and temperature. Further, from the results of phonon dispersion calculated at Zero Point Energy, pyrite structure exhibits ground state stability and the marcasite phase has all modes of frequencies positive. The newly proposed phase is a semiconductor with a band gap comparable to its pyrite counterpart but vary in optical absorption by around 10 cm. The various Ru doped structures have also shown similar optical absorption spectra in the same order of magnitude. We have used crystal field theory to explain high optical absorption which is due to the involvement of different electronic states in formation of electronic and optical band gaps. Lӧwdin charge analysis is used over the customarily Mulliken charges to predict 89% of covalence in the compound. Our results indicate the importance of new phase to enhance the efficiency of photovoltaic materials for practical applications.
一种第一性原理计算方法已被用于研究钌掺杂对白铁矿FeS的电子和光吸收特性的影响。此外，我们还在RuS中发现了一种新的白铁矿相，这与大多数研究的黄铁矿结构不同。新相满足了结构稳定性及其实际存在的所有必要标准。8 GPa的转变压力促使RuS的结构从黄铁矿转变为正交相。通过热力学计算，我们报道了新相在不同施加压力和温度范围内的稳定性。此外，从零点能处计算的声子色散结果来看，黄铁矿结构表现出基态稳定性，而白铁矿相的所有频率模式均为正值。新提出的相是一种半导体，其带隙与其黄铁矿对应物相当，但光吸收变化约10 cm。各种钌掺杂结构也显示出相似的光吸收光谱，其量级相同。我们使用晶体场理论来解释高光吸收现象，这是由于不同电子态参与了电子和光学带隙的形成。与传统的穆利肯电荷相比，我们使用洛丁电荷分析来预测该化合物中89%的共价性。我们的结果表明新相对提高光伏材料实际应用效率的重要性。
