Photoinduced Superparamagnetism in Nanostructured α-Fe2O3

被引：23
|
作者：
Macdonald, I. Ross [1 ]
Howe, Russell F. [1 ]
Saremi-Yarahmadi, Sina [2 ,3 ]
Wijayantha, K. G. U. [2 ,3 ]
机构：
[1] Univ Aberdeen, Dept Chem, Aberdeen AB24 3UE, Scotland
[2] Univ Loughborough, Dept Mat, Loughborough LE11 3TU, Leics, England
[3] Univ Loughborough, Dept Chem, Loughborough LE11 3TU, Leics, England
来源：
JOURNAL OF PHYSICAL CHEMISTRY LETTERS | 2010年 / 1卷 / 16期
基金：
英国工程与自然科学研究理事会;
关键词：
NANOPARTICLES; WATER; OXIDE; RESONANCE; ELECTRODES; PARTICLES; OXIDATION; HEMATITE; ANATASE; FILMS;
D O I：
10.1021/jz100650w
中图分类号：
O64 [物理化学（理论化学）、化学物理学];
学科分类号：
070304 ; 081704 ;
摘要：
This Letter reports a remarkable influence of light on the magnetic properties of nanocrystalline a-Fe203. EPR spectroscopy shows that the a-Fe203 is superparamagnetic, showing an intense narrow EPR signal at room temperature which shifts to a lower field and broadens to be barely detectable at 77 K Or below In situ irradiation of samples held in vacuo at 4 or 77 K with near-UVor visible light causes the appearance of an intense new EPR signal, which decays immediately after the irradiation is stopped. We suggest that the generation of conduction band electrons by irradiation Into the band gap of the a-Fe203 moderates the coupling between the magnetic domains in these nanocrystals This effect is largely suppressed in the presence of adsorbed oxygen, which can scavenge conduction band electrons.
引用
收藏
页码：2488 / 2492
页数：5
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