Low phonon energies and wideband optical windows of LaO-GaO glasses prepared using an aerodynamic levitation technique.

xLaO-(100 - x)GaO binary glasses were synthesized by an aerodynamic levitation technique. The glass-forming region was found to be 20 ≤ x ≤ 57. The refractive indices were greater than 1.92 and increased linearly with increasing x. The polarizabilities of oxide ions were estimated to be 2.16-2.41 Å, indicating that the glasses were highly ionic. The glasses were transparent over a very wide range from the ultraviolet to the mid-infrared region. The widest transparent window among the oxide glasses was from 270 nm to 10 μm at x = 55. From the Raman scattering spectra, a decrease in bridging oxide ions and an increase in non-bridging oxide ions were confirmed to occur with increasing LaO content. The maximum phonon energy was found to be approximately 650 cm, being one of the lowest among oxide glasses. These results show that LaO-GaO binary glasses should be promising host materials for optical applications such as lenses, windows, and filters over a very wide wavelength range.