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CoCr_2O_4纳米晶的制备及其磁性研究 被引量:3
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作者 毕红 蒋锡群 +2 位作者 杨昌正 李山东 都有为 《功能材料》 EI CAS CSCD 北大核心 2004年第3期293-295,共3页
 通过高分子金属络合物热解法制备了CoCr2O4纳米晶,并对它的表面微结构和磁性能进行了表征。通过高分辨电镜和傅立叶红外光谱的研究发现在平均粒径为12nm的纳米晶表面不仅有晶格缺陷,而且吸附有大量聚合物分解后的有机碎片,这些有机碎...  通过高分子金属络合物热解法制备了CoCr2O4纳米晶,并对它的表面微结构和磁性能进行了表征。通过高分辨电镜和傅立叶红外光谱的研究发现在平均粒径为12nm的纳米晶表面不仅有晶格缺陷,而且吸附有大量聚合物分解后的有机碎片,这些有机碎片对纳米晶表面磁矩的钉扎以及纳米晶自身的表面晶格缺陷,导致自旋无序的表面和相对自旋有序的核之间产生强的交换耦合作用,从而使得纳米晶呈现出奇特的磁性能,如低温下存在较大的矫顽力和偏置场等。 展开更多
关键词 高分子金属络合物热解法 COCr2O4 纳米晶 磁性
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Dielectric and ferroelectric properties of CoCr_(2)O_(4)nanoceramics
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作者 Pankaj Choudhar P.Saxena +2 位作者 A.Yadav V.N.Rai A.Mishra 《Journal of Advanced Dielectrics》 CAS 2019年第3期1-7,共7页
CoCr_(2)O_(4)nanoceramics are prepared by sol-gel auto combustion method.Synchrotron X-ray diffraction analysis affirms the singlephasepristine cubic structure with space group Fd3m.Debye-Scherrer method estimates the... CoCr_(2)O_(4)nanoceramics are prepared by sol-gel auto combustion method.Synchrotron X-ray diffraction analysis affirms the singlephasepristine cubic structure with space group Fd3m.Debye-Scherrer method estimates the crystallite size of main intense peak tobe~27:15 nm.Prominent bands obtained in infrared spectra at 448 and 599 cm^(-1)are due to metal-oxygen stretching bond presentat tetrahedral and octahedral sites.Dielectric parameters decrease as frequency increases from 103 to 106 Hz that can be interpretedby Maxwell-Wagner-type interfacial polarization.Complex impedance spectra(Nyquist plot)reveal arc like behavior,which ismainly due to intergrain(grain boundary)resistance that also exhibits conducting nature of the nanoceramics.Weak ferroelectricityis mainly associated with the partial reversal of the polarization.Leakage current behavior follows the Ohmic and Child square law.Electron conduction process was interpreted by space-charge limited current(SCLC)mechanism.Leakage current behaviorobserved in cobalt chromite nanoceramics is mainly attributed to the oxygen vacancies. 展开更多
关键词 CoCr_(2)O_(4)nanoceramics synchrotron X-ray diffraction dielectric spectroscopy electric polarization leakage currentbehavior
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