Optical properties of sodium β-alumina single crystals doped with neodymium and chromium–neodymium

Abstract

Single crystals of sodium β-alumina have been grown by two methods: flux evaporation and a new process, solid–vapour reaction. These compounds were doped with neodymium through a homogeneous ion-exchange reaction. Their X-ray diffuse scattering patterns show a two-dimensional (2D) superstructure (a√3; a√3) for Nd β-alumina. The optical behaviour of NaNd β-alumina single crystals is reported here. A strong absorption occurs at 580nm. Nd³⁺ emission shows a broad band (FWHM about 30 nm) centred at 1.06 µm and the Nd³⁺ lifetime measured at room temperature is about 530 µs. Finally, chromium-neodymium co-doped samples of β-alumina single crystals are investigated. Timeresolved spectroscopy and lifetime analysis indicate that Cr→Nd energy transfer takes place in this host matrix.