Abstract
Optical-absorption and electron paramagnetic resonance (EPR) techniques were used to study iron impurities in yttrium aluminum garnet (YAG) crystals. Due to its low symmetry, YAG containing exhibited many EPR lines. ions in octahedral and tetrahedral sites were identified. A correlation study involving both EPR and optical-absorption measurements indicated that the absorption band at 255 nm, which had been previously attributed to an charge-transfer band, was a composite charge-transfer band made up of contributions from substitutional at both symmetry sites. Oxidation and reduction experiments up to 1700 K were performed. The former increased the concentration, and the latter diminished it. Conversion of to was governed by a thermal activation energy of 3.0±0.3 eV.
- Received 15 March 1988
DOI:https://doi.org/10.1103/PhysRevB.38.8555
©1988 American Physical Society