Preparation and scintillation properties of translucent LiCaBO 3 :Ce polycrystalline plates

Abstract

Translucent LiCaBO 3 :Ce thin plates were prepared by liquid phase sintering using LiBO 2 as a sintering aid, and their fluorescent and scintillation properties were investigated to examine the possibility to use as neutron scintillator. Since the initial part of the directionally solidified specimen contained a second phase of Ca 3 B 2 O 6 , LiCaBO 3 may melt incongruently, and simple melt growth of LiCaBO 3 :Ce is consequently difficult. Translucent thin plates 300 µm in thickness were successfully fabricated from LiCaBO 3 :Ce sintered compacts. Although strong fluorescence with the peak wavelength of 390 nm was observed in photoluminescence measurement, scintillation light yield and detection efficiency by α-particle irradiation were rather poor. The diffuse reflectance spectrum of LiCaBO 3 :Ce revealed existence of an absorption band other than Ce 3+ bands in the ultraviolet region. The band may corresponds to defect levels, which interrupt the energy transfer from the conduction band of the host to the 5d level of Ce 3+ resulting in the degradation of the scintillation performance.