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采用固相反应法,制备出一系列SmCo1-xIrxAsO(x=0.05,0.1,0.15,0.2,0.25,0.3)多晶样品。XRD测试结果表明所有样品均具有ZrCuSiAs型四方结构,随着掺杂量的增加,晶格参数a变大,c变小。在x≥0.25时发现小部分杂相峰IrAs2,说明SmCo1-xIrxAsO体系单相样品较难制得。磁性测量结果表明,SmCo1-xIrxAsO在高温区表现出顺磁性。外场为10Oe时,掺杂量为0.05的样品随着温度的降低,依次在60K和45K附近出现铁磁转变和反铁磁转变,在低温区ZFC与FC曲线分离,出现明显的不可逆性。随着外磁场的增加,不可逆性受到抑制,铁磁转变温度TC向高温方向移动。增加掺杂量,样品铁磁反铁磁转变温度几乎不变,表明Ir掺杂对样品磁性没有影响。M-H曲线表明,温度T<30K时,所有掺杂样品随着磁场的增加,均出现反铁磁(AFM)-铁磁(FM)的磁性转变,且转变磁场随温度的升高而减小。T=50K时,这种变磁性转变消失,样品表现出软铁磁特性。
A series of SmCo1-xIrxAsO (x = 0.05,0.1,0.15,0.2,0.25,0.3) polycrystalline samples were prepared by solid-state reaction. XRD results show that all the samples have a ZrCuSiAs tetragonal structure. With the increase of doping amount, the lattice parameter a becomes larger and c decreases. When x≥0.25, a small part of the heterosked peak IrAs2 was found, which indicated that the single-phase SmCo1-xIrxAsO system was difficult to obtain. Magnetic measurements show that SmCo1-xIrxAsO exhibits paramagnetism at high temperature. When the external field was 10Oe, the samples with doping amount of 0.05 showed ferromagnetic and antiferromagnetic transition near 60K and 45K with the decrease of temperature. The separation of ZFC and FC curve in the low temperature region showed obvious irreversibility. With the increase of the external magnetic field, the irreversibility is suppressed, and the ferromagnetic transition temperature TC moves to the high temperature. Increasing the doping amount, the ferromagnetic antiferromagnetic transition temperature of the sample almost does not change, indicating that Ir doping has no effect on the magnetic properties of the sample. The M-H curves show that all the doped samples exhibit magnetic transitions of antiferromagnetic (AFM) -ferromagnetic (FM) with increasing magnetic field at T <30K, and the transition magnetic field decreases with increasing temperature. At T = 50K, the change of the magnetization disappears and the sample shows soft ferromagnetic properties.