反铁磁性
铁磁性
磁化
材料科学
透射电子显微镜
相(物质)
磁性
结晶学
居里温度
凝聚态物理
分析化学(期刊)
磁场
化学
纳米技术
物理
有机化学
量子力学
色谱法
作者
James D. Rall,M. S. Seehra,Naresh Shah,G.P. Huffman
摘要
For the two stable phases of Ni(OH)2, viz. α-Ni(OH)2 and β-Ni(OH)2, structural and magnetic properties are compared employing x-ray diffraction (XRD), scanning electron microscopy/transmission electron microscopy (TEM/SEM), and variation of the magnetization (M) with temperatures (2–350 K) and magnetic fields (up to ≈65 kOe). Both phases crystallize in the layered hexagonal structure with a=3.04 Å (3.12 Å) and c=23.6 Å (4.67 Å) for the α(β) phase with clear evidence for turbostraticity in the α-phase. From TEM/SEM, the β-phase consists of nanoplates of dimensions 30(10)×3(1) nm, whereas the α-phase has flowerlike morphology with petal thickness ≈5(1) nm. The low-field M versus T data for the zero-field-cooled/field cooled cases bifurcates at Tp=25 K (13 K) for the β(α) phase. For T>Tp, Curie–Weiss variation of M versus T is observed yielding positive θ=20.6 K (32 K) with μ=2.95 μB (3.13 μB) for the Ni2+ ions in the β(α) phase. The M versus H data at 2 K shows antiferromagnetic (ferromagnetic) like variation for the β(α) phase with dM/dH showing peaks at Hc1=28 kOe and Hc2=55 kOe for the β-phase. It is concluded that β-Ni(OH)2 is a metamagnet for T<TN=25 K, whereas α-Ni(OH)2 is a hard ferromagnet with Tc=13 K and domain structure for H<5 kOe.
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