On the Luminescence of HfGeO4:Ti4 + X-ray Phosphor and Luminescence Thermometer

Abstract

The HfGeO4:Ti phosphor was investigated, focusing on its thermoluminescence properties in the range of 30−500 °C and photoluminescence in the 13–600 K. The nominal Ti content was 1%, while 0.2% concentration was proved by EDS. The thermoluminescence exposed three TL peaks at 70, 120, and 180 °C whose properties were analyzed. Emissions peaking at 430 nm under 255 nm excitation, 580 nm under 320 nm, and 790 nm under 355 nm were identified and characterized. The latter two were not reported earlier. The 790 nm emission is suggested to result from slight contamination with rutile-TiO2. Contrary to the emission intensity, which slightly increased from 13 K to about 200 K, the decay time of the 430 nm luminescence started shortening at just about 40 K. The 580 and 790 nm luminescence is thermally quenched within ∼30–400 K range. Relative thermal sensitivity of 7.67%/K at 62 K (430 nm luminescence), and 6.04%/K at 73 K (580 nm) were achieved using decay time as the thermometric parameter. The HfGeO4:0.2%Ti appeared to be a very good luminescence thermometer operating in a wide range of 30–600 K, with sensitivities higher than 0.4%/K.