Thermal relaxation method to determine the specific heat of optical glasses

Abstract

In this work the thermal relaxation method is applied to determine the specific heat of the following optical glasses: undoped chalcohalides (As 2S 3 and 40PbI 2+30Sb 2S 3+30As 2S 3); undoped and Nd 2O 3 doped phosphate (38.66P 2O 5+40.22ZnO+21.12Na 2O) and low silica calcium aluminosilicate (47.4CaO+41.5Al 2O 3+7.0SiO 2+4.1MgO) glasses. For the latter the samples were melted both under vacuum and air conditions. Our results show that the specific heats of silica calcium aluminosilicate samples prepared under vacuum conditions were larger than that of the samples melted under air atmosphere. For chalcohalide glass sample (40PbI 2+30Sb 2S 3+30As 2S 3) the occurrence of a glass transition at 171 °C was observed. These results indicate that this simple and low cost method is an useful tool to measure the specific heat of glasses as a function of the temperature.