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首页> 外文期刊>Physical review >Properties of highly crystalline NiO and Ni nanoparticles prepared by high-temperature oxidation and reduction
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Properties of highly crystalline NiO and Ni nanoparticles prepared by high-temperature oxidation and reduction

机译：高温氧化还原制备高结晶NiO和Ni纳米粒子的性能

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摘要

We describe here the use of high-temperature oxidation and reduction to produce highly crystalline nanoparticles of Ni and NiO. Starting with an amorphous Ni powder, we demonstrate that oxidation at 900 ℃ produces faceted NiO nanocrystals with sizes ranging from 20 to 60 nm. High-resolution transmission electron microscopy measurements indicate near-perfect atomic order, truncated by (200) surfaces. Magnetization measurements reveal that the Neel temperature of these NiO nanoparticles is 480 K, substantially reduced by finite-size effects from the bulk value of 523 K. The magnetization of these faceted NiO nanoparticles does not saturate in fields as large as 14 T while a loop offset is observed which increases from 1000 Oe at 300 K to its maximum value of 3500 Oe at 50 K. We have used high-temperature reduction to transform the faceted NiO nanoparticles into highly ordered Ni nanoparticles, with a Curie temperature of 720 K and blocking temperatures in excess of 350 K. Subsequent efforts to reoxidize these Ni nanoparticles into the core-shell morphology found that the Ni nanoparticles are much more resistant to oxidation than the original Ni powder, perhaps due to the relative crystalline perfection of the former. At 800 ℃, an unusual surface roughening and subsequent instability was observed, where 50-nm-diameter NiO rods grow from the Ni surfaces. We have demonstrated that high-temperature oxidation and reduction in Ni and NiO are both reversible to some extent and are highly effective for creating the highly crystalline nanomaterials required for applications such as exchange-bias devices.
机译：我们在这里描述了使用高温氧化和还原来生产高度结晶的Ni和NiO纳米颗粒。从无定形的镍粉开始，我们证明了在900℃氧化会产生多面的NiO纳米晶体，尺寸在20至60 nm之间。高分辨率透射电子显微镜测量表明原子级接近完美，被（200）个表面截断。磁化强度测量表明，这些NiO纳米颗粒的Neel温度为480 K，受523 K体积值的有限大小影响而显着降低。这些多面NiO纳米颗粒的磁化强度在14 T的大磁场中不会饱和，而会发生循环。观察到偏移，该偏移从300 K时的1000 Oe增加到50 K时的最大值3500 Oe。我们已使用高温还原将切面NiO纳米颗粒转变为高度有序的Ni纳米颗粒，居里温度为720 K，并发生了结块。温度超过350K。随后将这些Ni纳米粒子重新氧化为核-壳形态的努力发现，Ni纳米粒子比原始Ni粉末具有更高的抗氧化性，这可能是由于前者的相对结晶完美。在800℃时，观察到异常的表面粗糙和随后的不稳定性，其中从Ni表面生长出直径为50 nm的NiO棒。我们已经证明，Ni和NiO的高温氧化和还原在一定程度上都是可逆的，并且对于产生诸如交换偏置器件之类的应用所需的高度结晶的纳米材料非常有效。

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  • 来源
    《Physical review》 |2010年第1期|014420.1-014420.9|共9页
  • 作者

    Mikhail Feygenson; Angela Kou; Lauren E. Kreno; Amanda L. Tiano; Jonathan M. Patete; Fen Zhang; Moo Sung Kim; Vyacheslav Solovyov; Stanislaus S. Wong; Meigan C. Aronson;

  • 作者单位

    Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA;

    Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA;

    Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA;

    Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA;

    Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA;

    Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA;

    Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA;

    Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA;

    Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA;

    Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA;

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  • 正文语种 eng
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  • 关键词

    fine-particle systems; nanocrystalline materials;

    机译：细颗粒系统;纳米晶材料;

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