Shape- and field-dependent Morin transitions in structured α-Fe2O3

被引：69

作者：

Mitra, Subarna ^{[2
]}

Das, Soumen ^{[1
]}

Basu, Soumen ^{[1
,3
]}

Sahu, Puspendu ^{[4
]}

Mandal, Kalyan ^{[2
]}

机构：

[1] Indian Assoc Cultivat Sci, Dept Mat Sci, Kolkata 700032, India

[2] SN Bose Natl Ctr Basic Sci, Dept Mat Sci, Kolkata 700098, India

[3] Natl Inst Technol, Dept Phys, Durgapur 713209, India

[4] Jadavpur Univ, Dept Phys, Kolkata 700032, India

来源：

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS | 2009年 / 321卷 / 18期

关键词：

alpha-Fe2O3; Solvothermal; Morin transition; MAGNETIC-PROPERTIES; IRON(III) OXIDES; MOSSBAUER; HEMATITE; SIZE; NANORODS; PROFILE;

D O I：

10.1016/j.jmmm.2009.04.044

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We report shape- and field-dependent magnetic properties of ellipsoid-, spindle-, flattened- and rhombohedra-shaped alpha-Fe2O3 samples prepared by solvothermal technique. We observed that a magnetic spin-flip mechanism, mostly known as Morin transition (T-M), depends on the shape of alpha-Fe2O3 as well as on the applied magnetic field. In each of these structures the obtained value of T-M was less than its bulk value of 263 K. We observed that T-M shifted from highest 251.4K for ellipsoid to lowest 220.8K for rhombohedra structure, with intermediate values of T-M for the other two structures. However, for rhombohedra structure T-M shifted from 220.8 to 177.5K under the external magnetic field of 100 Oe-30 kOe, respectively. The observed lowering of T-M in the structured sample was analyzed in terms of elementary size, shape of the nanocrystallites, lattice parameters and occupancyof Fe+3 ions as well. These parameters were determined from the Rietveld refinement process using MAUD software. (C) 2009 Elsevier B.V. All rights reserved.

引用

页码：2925 / 2931

页数：7

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