Temperature dependence of total hemispherical emittance in perovskite-type manganese oxides, La_(1-x)Sr_xMnO_3

摘要

La_(1-x)Sr_xMnO_3 is a manganese oxide with a perovskite-type structure, LaMnO_3, by substitution of La~(3+) sites with Sr~(2+), which shows a variety of phenomena with changing hole concentration (x). The total hemispherical emittance, ε_H, of La_(1-x)Sr_xMnO_3 (x = 0, 0.175 and 0.3) in the vicinity of the metal - insulator transition temperature was measured by the calorimetric method in the temperature range 173 - 373 K. Remarkable differences in ε_H resulted with changing hole concentration (x). It was observed that ε_H of La_(0.825)Sr_(0.175)MnO_3 changed notably at about 280 K accompanied by the metal - insulator transition and the maximum amount of variation in ε_H was 0.42. The effects of surface conditions and thicknesses of samples were also observed. The uncertainty in the measurement of ε_H was estimated to be at most ±2.2 from 173.15 to 373.15 K.