Structural, photo, optical and thermal luminescent properties of beta barium metaborate

Abstract

Barium borate compounds (BaB4O7 – β-BaB2O4) were produced by different synthesis methods, which include solution assisted solid state synthesis method (SAS), microwave assisted solid state synthesis method (MAS) and high temperature solid state synthesis method (HTS). These different synthesis methods were carried out in air atmosphere (AA) and nitrogen atmosphere (NA). Luminescence emission spectra of barium borate compounds exhibited a broad band around 400 nm (∼310 nm excitation). X- ray induced luminescence measurements have shown a similar emission band, supporting the PL measurements. Photoluminescence decay curve of β-BaB2O4 compound (excited with 365 nm) is well fitted with a double exponential function with lifetimes τ1=3,69 ms and τ2=29,45 ms. At around 365 nm, Quantum Efficiency (QE) of the luminescence emission from β-BaB2B4 was calculated as 8 ± 1 percent. In order to test the possibility of using in radiation dosimetry, Optically Stimulated Luminescence (OSL) properties of β-BaB2O4 were investigated by determining radiation dose response, fading and repeatability of response. The OSL signal intensity was observed to increase linearly with increasing beta dose from 5 Gy to 1000 Gy. Thermoluminescence (TL) glow curve of β-BaB2O4 phosphor consist of broad glow peak with an apparent maximum at around 240 °C; which is also growing with radiation dose. The results presented here are of preliminary in nature and for a better understanding of the luminescence properties of β-BaB2O4 deserves more attention with possible applications as a phosphor and optical and dosimeter material.