TL and OSL studies on lithium borate single crystals doped with Cu and Ag

Abstract

Lithium borate (LBO) single crystals doped with Cu and Ag (0.25mol% each) (Li2B4O7:Cu,Ag) are grown by the Czochralski method. The thermoluminescence readout on Li2B4O7:Cu,Ag crystals showed three glow peaks at∼375, 441 and 516K for the heating rate of 1 K/s. The thermoluminescence sensitivity of the grown Li2B4O7:Cu,Ag single crystals is found to be 5 times TLD-100 and a linear dose response in the range 1mGy to 1kGy. The glow curve deconvolution reveals nearly first order kinetics for all the three peaks with trap depths 0.77, 1.25 and 1.34eV respectively and corresponding frequency factors 1.6×109, 1.3×1013 and 6.8×1011s−1. The continuous wave optically stimulated luminescence (CW-OSL) measurements were performed on the LBO:Cu,Ag single crystals using blue light stimulation. The traps responsible for the three thermoluminescence peaks in Li2B4O7:Cu,Ag are found to be OSL sensitive. The qualitative correlation between TL peaks and CW-OSL response is established. The photoluminescence studies show that in case of co-doping of Ag in LBO:Cu the emission at 370nm in Cu states dominates over the transitions in Ag states implying doping of Ag plays a role as sensitizer when co-doped with Cu and increases overall emission.