Infrared Absorption at Longitudinal Optical Frequency in Amorphous Oxides and Their Mixtures

Abstract
Infrared absorption at longitudinal optical (LO) frequency was measured in amorphous aluminum oxide, amorphous magnesium oxide and their mixtures. It was found that the LO mode of a mixture of these oxides has a single peak, and its position lies between those of the constituents if two oxides are mixed on the order of angstroms. The LO mode of amorphous MgAl2O4 is also reported.