Fe掺杂对YCrO3微结构及磁特性的影响

Influence of Fe doping on microstructure and magnetic properties of YCrO3

利用溶胶-凝胶法制备YCr0.6Fe0.4O3样品,研究了Fe^3+掺杂对YCrO3的微结构与磁特性的影响。结果表明,样品具有良好的单相正交结构,属于Pnma空间群。拉曼及傅里叶红外光谱结果显示,Fe^3+掺杂使得Y/Cr-O键长被拉伸,增加了晶格畸变,导致振动模式向低波数偏移。热磁M-T曲线表明,体系在TN^183K发生反铁磁相变,随温度降低磁化强度增加,FC曲线在128K出现较宽的驼峰,温度降至85K,磁化强度达到最小(0.08 A·m^2/kg),随后逐渐增加。这主要是Fe^3+掺杂使YCrO3样品内Cr^3+O^2-Cr^3+、Fe^3+O^2-Fe^3+反铁磁有序与Cr^3+O^2-Fe^3+铁磁相互作用共存,Fe/Cr团簇导致磁化反转现象。当T<80K时,M-H曲线出现磁台阶效应,T=50K时出现交换偏置现象,场冷磁场增加,磁滞回线基本重合,表明样品内反铁磁和铁磁界面处产生钉扎效应。

YCr0.6Fe0.4O3 sample was synthesized by sol-gel method and the microstructure and magnetic properties of Fe^3+doped YCrO3 sample were investigated systematically.The XRD patterns showed that the sample presented good single-phase orthogonal structure with space group Pnma.Fourier transform infrared spectroscopy(FTIR)and Raman spectra results showed the vibration modes of YCr0.6Fe0.4O3 shifted to low wave-number in comparison with YCrO3,owing to the increase of Y/Cr-O band lengths and lattice distortion resulting from the substitution of Fe^3+.M-T curves indicated that the antiferromagnetic phase transition occurred at TN=183 K.With the decrease of temperature,the magnetization increased and a wide peak appeared at 128 K.Further cooling,the magnetization reached to minimum value 0.08 emu/g at 85 K and then increased gradually.The phenomenon was ascribed to the coexisting Cr^3+O^2-Cr^3+,Fe^3+O^2-Fe^3+antiferromagnetic order and Fe^3+O^2-Cr^3+ferromagnetic interaction as well as the magnetization reversal caused by the Fe/Cr-rich cluster in Fe3+doped YCrO3 system.Below 80 K,the magnetic step effect was observed in M-H curves.Meanwhile,the sample also exhibited an typical exchange bias effect at T=50 K in field cooling condition and hysteresis loops were coincident basically with increasing fields,suggesting the pinning effect of the antiferromagnetic phase to the ferromagnetic phase in the investigated YCr0.6Fe0.4O3 sample.