Spectroscopic studies of Ti3+ ions speciation inside MgAl2O4 spinels

• Published in: Journal of crystal growth Vol. 311; no. 3; pp. 899 - 903
• Main Authors: LOMBARD, P, BOIZOT, B, OILIER, N, JOUINI, A, YOSHIKAWA, A
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Amsterdam Elsevier 15.01.2009
• Subjects: Condensed Matter; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Growth from melts; zone melting and refining; Materials Science; Methods of crystal growth; physics of crystal growth; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Aluminium oxide; 61.66.Fn; Pressure effects; Magnesium oxide; Doping; 76.30.Fc; A1. Crystal structures; A1. Characterization; Spinels; Paramagnetic materials; A2. Growth from melt; Titanium; Chemical composition; Optical materials; Growth from melt; Electron paramagnetic resonance; Titanium compounds; Titanium oxide; B1. Titanium compounds; 76.30.-v; Crystal structure
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2008.09.131

An electron paramagnetic resonance (EPR) investigation on Ti-doped MgAl2O4 spinels has been made in order to study the Ti3+ sites. The study we present here concerns the angular dependencies of the Ti3+ EPR lines and the variations of the EPR spectra due to a modificatino of the TiO2 content or of the chemical composition from MgAl2O4 to MgAl4O7 and MgAl6O10. In all the studied samples except one, we observe the presence of both Mn2+ and Ti3+ ions. No correlation was observed between Ti3+ amount and TiO2 content; The titanium ions are located in three different sites: the octahdral B site of the spinel structure; the tetrahedral A site and a last site which remains unclear. On the contrary, the major part of the Mn2+ ions is assumed to be in the tetrahedral A site of the spinel structure and a minor part in the octahedral B site. Our work demonstrates the overall interest of EPR spectroscopy in the study of the paramagnetic optically active ions inside optical materials.