Crystallization and spectroscopic properties of electron-beam-deposited, chromium-doped, forsterite films

A sol−gel prepared, chromium-doped, magnesium- and silicon-containing oxide mixture was used as a target material for the electron-beam deposition of 1.2 μm thick chromium-doped forsterite films onto single-crystal quartz substrates. The stoichiometry of the target materials was adjusted to compensate for the disparate volatilities of the component oxides. X-ray diffraction revealed that the as-deposited films were amorphous, and the refractive indices of the films revealed that they were near full density. Heating the films to 650 °C produced isolated crystallites of forsterite that ranged in size from 50 to 250 nm in an amorphous matrix (by TEM). Only films that had been heated to 725 °C and above revealed Cr4+ emissions.