Growth and luminescence properties of γ-CuBr single crystals by the Bridgman method

Abstract

The growth of fast scintillation γ-CuBr crystals with a large size and high quality still is a serious challenge. In this work, γ-CuBr single crystals of ∅22 mm × 20 mm size were successfully grown from melt by the Bridgman method. The obtained γ-CuBr single crystals were characterized by XRD, DTA, etc. Transmission spectra, fluorescence spectra, X-ray excitation spectra and photoluminescence decay times were measured. The results show that the γ-CuBr single crystals have good optical homogeneity with a 75% optical transmittance in the wavelength range of 300–800 nm, and with a 2.87 eV direct band gap. The γ-CuBr single crystals have emission peaks at around 460 nm, 495 nm and 660 nm, which are attributed to the emission of free excitons, copper vacancies and bromine deficiency respectively. The decay time of the free exciton is about 9 ns. This implies that γ-CuBr crystals may have potential application in fast radiation detection.