稀土元素钇和钬掺杂对铁酸铋磁性能的影响

Effects of rare earth elements yttrium and holmium doping on magnetic properties of bismuth ferrite

铁酸铋是一种典型的单相多铁性材料,宏观上磁性很弱,为了改善其磁性能,用稀土元素钇和钬对其A位元素进行替代.采用水热法制备掺钇和掺钬的铁酸铋系列粉末样品,然后将这些粉末样品采用常规的固相反应法制备出陶瓷样品.以浓度12.5mol/L的氢氧化钾为矿化剂,反应温度为240℃,反应时间为24h时,得到了掺钇和掺钬的铁酸铋样品.X射线衍射结果显示,当掺杂量小于或等于0.05时,样品结构为纯相的三方铁酸铋结构,当掺杂量大于0.05时,出现了越来越多的杂相;通过振动样品磁强计测试样品的磁性能,发现所有样品都观察到了饱和的磁滞回线,说明掺钇和钬都能明显改善铁酸铋的磁性能;通过对比掺钇和掺钬所有样品的饱和磁化强度值,发现掺杂量相同时,掺钇样品的饱和磁化强度值都要比掺钬的大,而相同大小的钇离子没有磁性,钬离子有磁性,说明稀土离子本身的磁矩可能不是铁酸铋磁性增强的主要因素.

Bismuth ferrite is a kind of typical single phase multiferroic material, its macro magnetic property is poor. To improve the magnetic performance, rare elements yttrium and holmium were used to replace A-site of bismuth ferrite. The yttrium-doped and holmium-doped powder samples were prepared using hydrothermal method, and the ceramics were fabricated using these powders by conventional solid state reaction. When 12.5 mol/L potassium hydroxide was used as a mineralizer, the reaction temperature was 240 ℃ and reaction time was 24 h , yttrium-doped and holmium-doped bismuth ferrite particles were synthesized. The X-ray diffraction patterns reveal that a pure rhombohedral bismuth ferrite phase can only be obtained at doping amount χ≤0.05, with the increase of doping, more and more impurities appear. Magnetic measurement shows saturated magnetization and hysteresis loop for all the doped samples, indicating enhanced magnetism by yttrium and holmium doping. The yttrium-doped samples possess larger saturation magnetization comparing to the holmium- doped samples on the same doping amount. As yttrium ion and holmium ion in the similar size are nonmagnetic and magnetic respectively, the results suggest that the magnetic moment of the doping ions may not be the major impact factor for the magnetic enhancement of doped bismuth ferrite.