Materials Science in Semiconductor Processing 107 (2020) 104800 Available online 21 November 2019 1369-8001/© 2019 Elsevier Ltd. All rights reserved. Cation effect on electronic, optical and thermoelectric properties of perovskite oxynitrides: Density functional theory Amjid Mahmood a , Sikander Azam a, * , Muhammad Irfan b , Muhammad Arshad Kamran c , Thamer Alharbi c , Abdul Majid c , Muhammad Waqas Iqbal a , Shabbir Muhammad d, h , Abdullah G. Al-Sehemi e, h , Saleem Ayaz Khan f , Souraya Goumri-Said g a Faculty of Engineering and Applied Sciences, Department of Physics, RIPHAH International University, I-14 Campus, Islamabad, Pakistan b Department of Physics, University of Sargodha, 40100, Sargodha, Pakistan c Department of Physics, College of Science, Majmaah University, Al-Majmaah, 11952, Saudi Arabia d Department of Physics, College of Science, King Khalid University, Abha, 61413, P.O. Box 9004, Saudi Arabia e Research Center for Advanced Materials Science (RCAMS), Department of Chemistry, College of science, King Khalid University, Abha, 61413, P.O. Box 9004, Saudi Arabia f New Technologies e Research Center, University of West Bohemia, Univerzitni 8, 306 14, Pilsen, Czech Republic g College of Science, Physics department, Alfaisal University, P.O. Box 50927, Riyadh, 11533, Saudi Arabia h Research Center for Advanced Materials Science (RCAMS), King Khalid University, P.O. box 9004, Abha 61413, Saudi Arabia A R T I C L E INFO Keywords: Perovskite oxynitrides Optoelectronic properties Thermoelectric properties DFT calculations ABSTRACT Perovskite oxynitride are of great interest due to their use as photo-catalysts. We investigated the electronic, thermoelectric and optical properties of ATaO 2 N (A ¼ Ba, Sr, Ra) with generalized gradient plus Hubbard approximation (GGA þ U). In electronic properties, we have computed, for each compound, densities of states (total and partial), band structure to extract their band gaps, nature and transition probability when the cation changes. Optical properties were explored by calculating dielectric constant ε (ω), refractive index n (ω), refectivity R (ω), optical loss L (ω), and absorption coeffcient I (ω) response against different photon energies. In order to examine the possibility of using these compounds in thermoelectric devices, we calculated their transport properties from Boltzman transport theory. We examined their thermal conductivity κ, electrical conductivity σ, seebeck coeffcient S, power factor PF and dimensionless fgure of merit ZT. 1. Introduction In 1839, Gustav Rose discovered calcium titanium oxide (CaTiO3) in Russia Mountain which later obtained the name of Perovskites after the name of Count Lev Aleksevich Von Perovski (1792–1856) [1]. Perov- skites have general formula of “ABX 3 ” where “A” and “B 00 are different size cations “X” is anion. “X” have bonding with both “A” and “B”. Usually “X” is oxygen but other anions are also possible like nitride sulfde and halides. Due to multifunction properties for magnetic, electronic, dielectric, energy conversion and catalytic application there is increase in demand of novel perovskite-type materials [2]. Over last few decays intense studies have been done to check the effect of structure substitution on physical and chemical properties of perovskite-related oxides. This work is mostly based on cationic sub- stitution. These substitutions are depending on oxygen vacancies as they are randomly ordered so each substitution and may produce new structures. These substitutions can strongly change the properties of perovskites ionicity and the charge of metal ion bond. The substitution with oxygen is very limited because of geometrical reasons. One such substitution is replacement of nitrogen with oxygen. This substitution give birth to oxynitride. These perovskite-type structures with oxy- nitrides have shown more importance in various applications. By introducing nitrogen to these materials, it reduces the optical gap value and modifes the absorption properties of substances. Furthermore, compared to oxides, the oxynitrides are often colored. The frst such colored oxynitride was obtained by substituting titanium within BaTiO 3 . Also they are stable against acid, good temperature stability, low density and non-toxic [3]. The syntheses, crystal structures, electrical properties, and optical absorbance spectra of six perovskite oxynitrides, AMO 2 N (A ¼ Ba, Sr, Ca; * Corresponding author. E-mail address: Sikander.physicst@gmail.com (S. Azam). Contents lists available at ScienceDirect Materials Science in Semiconductor Processing journal homepage: http://www.elsevier.com/locate/mssp https://doi.org/10.1016/j.mssp.2019.104800 Received 27 July 2019; Received in revised form 6 October 2019; Accepted 25 October 2019