Mechanism of light scattering defects formation in NaI:Tl during crystal growth

Abstract

Nature of growth light scattering defects in NaI:Tl crystal has been studied by optical and electron microscopy technique. The heterogeneous mechanism of inclusion formation has been proposed. This mechanism consists in three stages. At first stage, sodium oxide diffuses to the internal surfaces of gas bubbles or channels. The oxide then reacts with carbon dioxide and converts into sodium carbonate. At the third stage, a new phase is formed inside the gas-filled channels. Finally carbonates covered internal surface of gas channels due to the shape of inclusion becomes morphologically stable.