Thermal expansion of lanthanum and neodymium oxides from 300–1000 K from measurements of attenuation of gamma rays

Abstract

The present communication is a study of the linear attenuation coefficients, density and thermal expansion of oxides of lanthanum and neodymium as a function of temperature from 300–1000 K. The values of thermal expansion have been determined from linear attenuation coefficient of gamma rays and density in the range 300–1000 K. Measurements on the attenuation of gamma rays have been made with an experimental set up assembled in our laboratory using narrow beam geometry method. Radioactive gamma source 137Cs (0.662 MeV) has been used for making measurements. The results on the linear gamma ray attenuation (μ l), density (ρ) and the coefficient of linear thermal expansion (α) of Lanthanum oxide (La2O3)and Neodymium oxide (Nd2O3) as a function of temperature have been fit to a second degree polynomial equation. The linear attenuation coefficient (μ l) of La2O3 shows a decrease from 50.87 m−1 at 350 K to 49.96 m−1 at 1000 K. The linear attenuation coefficient (μ l) of Nd2O3 shows a decrease from 59.04 m−1 at 350 K to 58.07 m−1 at 1000 K. The decrease in density for lanthanum and neodymium oxides from 350–1000 K is 1.79% and 1.64% respectively. The present results on the thermal expansion of La2O3 and Nd2O3 have been compared with the results obtained from x-ray diffraction method.