| 摘要 |
FIELD: chemistry.SUBSTANCE: calcium-doped lanthanum manganite is obtained by reaction from lanthanum, manganese and calcium oxides by their grinding, first annealing in air at 1350±50°C, cooling to room temperature, re-grinding and pressing obtained material in tablets, its re-annealing in air at 1350±50°C, further annealing in oxygen and cooling to room temperature, with obtaining samples with composition LaCaMnO, in which selected calcium concentration is 0.05<x<0.22, selected manganese concentration is 0<z?0.05, first annealing in air is carried out for 12 hours, second re-annealing in air is carried out for 4 hours, annealing in oxygen is carried out at T=650±20°C for 50 hours, and further cooling to room temperature is carried out in air at rate not lower than 10°C/min.EFFECT: material is simple in manufacturing and comparatively cheap, has high magnet-resistance in broad area of temperatures 5-300 K and especially high values of magnet-resistance at nitrogen and helium temperatures.5 dwg, 3 tbl |
