采用溶胶-凝胶法制备了纳米La(1-x-y)CaxSryMnO3系列粉体,经压片后烧结成陶瓷。用振动样品磁强计测量样品的磁化强度随温度的变化,结果表明各样品的居里温度在250-330K温度范围内,| M/ T|最大值在1.353-3.392A·m2/kg·K范围内变化。用差示扫描量热仪(DSC)测定了各样品相变温度和相变潜热,得出各样品的相变潜热在0.852-2.381J/g范围内,相变潜热较大的样品其|d M/dT|最大值也较大;另外,La0.8-xCa0.20SrxMnO3(x=0.05、0.08、0.10)样品的|dM/dT|最大值较大,并且居里温度在室温附近,有可能成为室温附近的磁制冷材料。
A series of nanocrystalline powder of La(1-x-y)CaxSryMnO3 was prepared by sol-gel technique, then
was pressed and annealed to form ceramic. The results of magnetic measurement show that the Curie temperature of all the samples varies from 250K to 330K,
and the maximal absolute value of (dM/dT) varies from 1.353 to 3.392A·m2/kg·K. The differential scanning calorimetry (DSC)
measurements indicate that the latent heat in phase transition changes from 0.852 to 2.381J/g and increases with the increase of the maximal absolute values of (dM/dT).
In addition, the maxial absolute value of (dM/dT) of La0.8-xCa0.20SrxMnO3(x=0.05, 0.08, 0.10) is also larger. Their Curie
temperatures are adjacent to room temperature and they can be used as magnetic refrigeration materials at about room temperature.
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