Site occupancy and spectroscopic properties of Mn4+ in double perovskites, La2MgGeO6

• Published in: Optical materials Vol. 94; no. C; pp. 148 - 151
• Main Authors: Srivastava, A.M., Smith, D.J., Brik, M.G.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2019; Elsevier
• Subjects: Bonding covalence; Crystal-field theory; Double perovskites; La2MgGeO6; Mn4; La2MgGeO6; Mn4; Crystal-field theory; Double perovskites; Bonding covalence
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2019.05.043

The spectroscopic properties of Mn4+ (3 d3) in the La2MgGeO6 double perovskite is the subject of this investigation. The optical data have been used to perform detailed crystal field calculation of the Mn4+ energy level scheme. In La2GeMgO6, the Mn4+ can occupy either the octahedral Mg2+ or the Ge4+ sites. To address the question of site occupation, the Mn4+ energy levels were calculated when the ion substitutes for the Mg2+ and Ge4+ sites of the double perovskite lattice. An unambiguous decision on the site occupation cannot be reached based on our calculations. A comparative study of the variations in the energy of the 2Eg→4A2g emission transition in a series of materials with the double perovskite structure is presented. The energy of the 2Eg→4A2g emission transition tends to increase with increasing distortion of the octahedral O–Mn–O bond angle from the ideal 90°. •Spectroscopic properties of Mn4+ in the double perovskite La2MgGeO6 is reported.•The Mn4+ energy levels are calculated using the exchange chare model of crystal-field theory.•A comparative study of the variations in the 2Eg.→4A2g emission energy in a series of double perovskites is presented.