多孔氧化镍纳米片的制备及其磁性能研究

采用水热合成法制备了大孔径和小孔径两种多孔氧化镍纳米片.采用透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、全自动比表面及孔隙度分析仪以及超导量子相干磁强计等对它们的形貌、晶体结构、比表面积以及磁性能进行了表征,并且探讨了这两种不同孔径氧化镍纳米片的形成机制.研究结果显示:这两种多孔NiO纳米片在55 K和300 K温度下都呈现类铁磁性,而小孔径NiO纳米片显示具有更高的饱和磁化强度,这可能是由于小孔径氧化镍纳米片拥有较大的开孔密度和比表面积,表面缺陷增多导致其表面自旋无序度增加,超反铁磁性效应更加显著.

Preparation and magnetic properties of porous NiO nanoplates

Two kinds of porous NiO nanoplates with different pore sizes were successfully prepared by hydrothermal synthesis.Their morphology,crystalline structures,BET surface area and magnetic properties were characterized by using transmission electron microscopy(TEM),X-ray diffractometer(XRD),ASAP 2020 surface area and porosity analyzer,and superconducting quantum interference device magnetometer(SQUID).In addition,the possible formation mechanism of the different porous NiO nanoplates was discussed.The results show that both porous NiO nanoplates present ferromagnetic-like behaviors.However,the porous NiO with a smaller pore size and larger surface area exhibits a higher saturation magnetization Ms than that of the porous NiO with a bigger pore size and less surface area.This result can be attributed to the larger pore density and specific surface area which may enhance the surface spin disorder and thus lead to a larger magnetization and remanent magnetism.