Critical Review—A Review of the Electronic Structure and Optical Properties of Ions with d3Electron Configuration (V2+, Cr3+, Mn4+, Fe5+) and Main Related Misconceptions

Tetravalent manganese ions with the 3d 3 electronic configuration have recently began to play a major role as a red photon generator in the LED based lighting and display devices. The goal of this article is to tutorize the fundamental optical properties of Mn 4+ and to clear up some common misconceptions that we have encountered in the archival literature that pertains to the spectroscopic properties of this ion and other ions with the same electron configuration. The methods to properly interpret the optical spectra of these systems are also discussed. This is accomplished by presenting a discussion on the electronic properties of the free d 3 ions and the changes which occur when the ion is introduced in a crystalline lattice. It is hoped that such systematic presentation of spectroscopic properties of the d 3 ions and their variation from the free state to the crystalline solids will be useful for many researchers – mainly experimentalists – actively working in the field and will help them avoiding many mistakes when presenting their experimental results.