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采用传统简便的固相烧结法制备了四方相的室温铁磁Sr3YCo4O10.5+δ多晶.热分析、X射线衍射和扫描电镜结果表明Sr3 YCo4 O10.5+δ多晶最终烧结温度应在963℃以上,较佳的烧结温度为1180℃.Sr3YCo4O10.5+δ多晶在80～300K为半导体电输运行为,较佳烧结温度多晶的室温电阻率～78.8 mΩ·cm;多晶热电势在317～1018 K随温度增加而减小,317 K时为70.74 μV/K.磁化强度-温度曲线、磁滞回线结果表明,多晶在受外加磁场、温度及晶体场的影响下,内部Co3+自旋态及磁畴壁、磁矩方向发生改变,导致多晶磁化强度变化及多晶磁性的改变.外磁场(0.1 T)下的ZFC曲线在320 K出现磁化强度最大为0.46 emu/g的Hopkinson峰,居里温度(Tc) =323 K,而FC曲线在奈尔温度(TN)=264 K时磁化强度达到最大为1.1 emu/g,TC=320 K.ZFC、FC方式下多晶均表现为室温铁磁性.

Room temperature ferromagnetic Sr3YCo4O10.5+δ polycrystals with tetragonal structure were prepared by solid-state sintering method.The Sr3YCo4O10.5+δ polycrystals were characterized by thermogravimetricdifferential scanning calorimetry,X-ray diffraction and scanning electron microscopy.The results indicate that the final sintering temperature should be above 963 ℃,and the optimal sintering temperature was 1180 ℃ within our experiments.The Sr3YCo4O10.5+δ polycrystals show semiconductor behavior at 80-300 K,and the room-temperature resistivity reached its minimum of ～78.8 rΩ · cm with the optimal sintering temperature.The thermopower of polycrystals decreased with increasing temperature in at 317-1018 K,and the thermopower was 70.74 μV/K at 317 K.The magnetization-temperature curves and hysteresis loops showed that the spin states of internal Co3 +,magnetic domains and orientations of magnetic moments changed under the influence of applied magnetic field,temperature and crystal field,resulting in different magnetizations and magnetic states.With the applied magnetic field of 0.1 T,the Hopkinson peak with the largest magnetization of 0.46 emu/g was observed at 320 K in the ZFC curve,and the Curie temperature(Tc) was 323 K.While the largest magnetization of 1.1 emu/g was obtained at the Neel temperature(TN) of 264 K in the FC curve,and Tc was 320 K.The polycrystals all show room-temperature ferromagnetism in both ZFC and FC curves.