Phase analysis of AlFe2B2 by synchrotron X-ray diffraction, magnetic and Mössbauer studies
Phase analysis of AlFe2B2 by synchrotron X-ray diffraction, magnetic and Mössbauer studies
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DOI：
10.1016/j.pnsc.2017.03.007
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发表时间：
2017-04
期刊：
影响因子：
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通讯作者：
Tahir Ali;Masaud Khan;E. Ahmed;Asad Ali
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文献类型：
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作者：
Tahir Ali;Masaud Khan;E. Ahmed;Asad Ali
用电弧熔炼法制备了纯相的AlFe 2B 2和含杂质的AlFe 2B 2样品，并对其结构和磁性进行了比较。通过同步加速器X射线衍射、磁性测量和穆斯堡尔谱进行了分析。同步辐射X射线衍射数据分析证实了AlFe_2B_2的正交结构，空间群为Cmmm，主要杂质相为Al_（13）Fe_（4+）。磁性测量表明AlFe 2B 2处于非饱和铁磁态，其转变温度Tc为286 K.在5 K下的等温磁化强度测量得到每个Fe原子的饱和磁化强度为0.7 μ B，而Arrott图则确定了铁磁转变的二级性质。穆斯堡尔谱的热演化证实了这种材料的铁磁性质，揭示了73 kOe的超精细场和在100 K时0.46 mm/s的同质异能素位移。比较了纯相样品和含杂质相样品的穆斯堡尔谱。本文认为，纯相材料穆斯堡尔谱中的低温顺磁贡献可能源于晶体结构中的缺陷或不均匀性所引起的某些本征现象。
The structural and magnetic properties of essentially phase pure AlFe2B2prepared by arc melting were compared with a sample containing impurities. Analysis was carried out by means of synchrotron X-ray diffraction, magnetic measurements and Mössbauer spectroscopy. The analysis of synchrotron X-ray diffraction data confirmed the orthorhombic structure of space groupCmmmfor AlFe2B2with Al13Fe4as main impurity phase. The magnetic measurements revealed an unsaturated ferromagnetic state in AlFe2B2with a transition temperature (Tc) of 286 K. Isothermal magnetization measurment at 5 K gave a saturation magnetization of 0.7 μBper Fe atom while Arrott plots establish the second order nature of ferromagnetic transition. The thermal evolution of Mössbauer spectra confirmed the ferromagnetic nature of this material revealing an hyperfine field of 73 kOe and an isomer shift of 0.46 mm/s at 100 K. The Mössbauer spectra of a phase pure sample was compared with the one containing impurity phases. It is suggested that the low temperature paramagnetic contribution in Mössbauer spectra of phase pure material may have its origin in some intrinsic phenomena arising from defects or inhomogeneities in crystal structure.