Size-dependent shifts of the Néel temperature and optical band-gap in NiO nanoparticles
Size-dependent shifts of the Néel temperature and optical band-gap in NiO nanoparticles
复制标题
NiO 纳米颗粒中尼尔温度和光学带隙的尺寸依赖性变化
DOI：
10.1063/1.4838915
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发表时间：
2013
影响因子：
3.2
通讯作者：
M. Seehra
中科院分区：
文献类型：
--
作者：
S. Thota;J. Shim;M. Seehra
块体NiO是众所周知的反铁磁体，其Neel温度TN（∞）= 524 K，光学带隙Eg = 4.3 eV。随着NiO颗粒尺寸D从40 nm减小到4 nm，TN和Eg的系统变化在这里观察和讨论。根据磁场测量，TN随D的变化符合有限尺寸标度方程TN（D）= TN（∞）[1 −（λ o/D）λ]，其中λ = 3.2 ± 0.5，λ o = 3.2 ± 0.2 nm，与海森堡系统的预测非常一致。观察到的蓝移的Eg与D的减少达到Eg = 5.12 eV的D为4 nm的可能是由于量子限制和非化学计量。
Bulk NiO is a well-known antiferromagnet with Neel temperature TN(∞) = 524 K and an optical band-gap Eg = 4.3 eV. With decrease in particle size D from 40 nm to 4 nm of NiO, systematic changes of TN and Eg are observed and discussed here. From magnetic measurements, the changes in TN with D are found to fit finite-size scaling equation TN(D) = TN(∞) [1 − (ξo/D)λ] with λ = 3.2 ± 0.5 and ξo = 3.2 ± 0.2 nm, in good agreement with the predictions for a Heisenberg system. The observed blue shifts of Eg with decrease in D reaching Eg = 5.12 eV for D ∼ 4 nm are likely due to quantum confinement and non-stoichiometry.