The cobalt ferrite nanoparticles were prepared by coprecipitation in the presence of poly (N-vinylpyrrolidone) (PVP) and characterized by XRD, TEM, EDX and magnetometry. XRD results suggest the formation of pure cobal...The cobalt ferrite nanoparticles were prepared by coprecipitation in the presence of poly (N-vinylpyrrolidone) (PVP) and characterized by XRD, TEM, EDX and magnetometry. XRD results suggest the formation of pure cobalt ferrite. The mean particle sizes of CoFe2O4 samples annealed at 400 ℃ and 600 ℃ were ca. 6 and 25 nm, respectively as obtained by transmission electron microscopy (TEM). The magnetic measurements indicated that nano-particles obtained at 400 ℃ were superparamagnetic while that prepared at 600 ℃ were ferrimagnetic.展开更多
运用密度泛函理论的第一性原理计算分析了MgZn2相的电子结构及相关磁性质。能带结构和态密度分析表明Zn4s和Zn4p轨道、Mg3s和Mg3p轨道分别发生sp态杂化,然后杂化态之间相互作用而形成Zn-Mg键;Mulliken布居分布计算显示:Zn1-Mg(Zn1是处...运用密度泛函理论的第一性原理计算分析了MgZn2相的电子结构及相关磁性质。能带结构和态密度分析表明Zn4s和Zn4p轨道、Mg3s和Mg3p轨道分别发生sp态杂化,然后杂化态之间相互作用而形成Zn-Mg键;Mulliken布居分布计算显示:Zn1-Mg(Zn1是处于晶格边缘的Zn原子)和Zn2-Mg(Zn2是处于晶格内部的Zn原子)电子云重叠布居数接近0,电子密度分析显示Zn-Mg之间电子密度分布具有明显的定域性。结合上述结果与Zn、Mg原子的电负性差异,确定Zn-Mg键为极性共价键。分态密度(PDOS)分析显示,Zn1-Mg键和Zn2-Mg键的差异主要表现在Zn24s轨道在-10^-6 e V区域对成键的贡献度高于Zn14s轨道,而Zn14s轨道在2~5 e V区域对成键的贡献度高于Zn24s轨道。进一步对MgZn2的积分自旋态密度和磁矩计算表明:MgZn2磁性质表现为顺磁性,其磁性主要来源于Zn1-Mg键中的2个自旋相同的未配对电子;MgZn2的顺磁性特性将使Al-Zn-Mg-Cu(7×××系)高强铝合金产生磁致塑性效应。展开更多
A new cyano bridged assembly,2·5H2O, prepared by slow diffusion of an aqueous solution of K2 and an aqueous solution of ClO4 in an U tube, has been characterized by X ray structure analysis, IR and magnetic measu...A new cyano bridged assembly,2·5H2O, prepared by slow diffusion of an aqueous solution of K2 and an aqueous solution of ClO4 in an U tube, has been characterized by X ray structure analysis, IR and magnetic measurements. The crystal crystallizes in orthorhombic, space group Pnna, a=2.8189(5)nm, b=0.8407(2)nm, c=1.4554(2)nm, V= 3.4491(11)nm3 and Z=4. The complex is built up of infinite chains which are formed by trans Ni(en)2 μ (NC)2, cis μ (NC)2Ni(CN)2 and cis μ (CN)2Ni(en)2 groups. The variable temperature magnetic susceptibility has been measured in the 5～300K range. A magnetic susceptibility study indicates the presence of a weak antiferromagnetic interaction and gives it’s weiss constant θ=2.6K. CCDC: 207329.展开更多
采用第一性原理密度泛函理论系统地研究Mn原子单掺杂和双掺杂ZnS纳米管的结构、电子性质和磁性质.掺杂纳米管的形成能比纯纳米管形成能更低,表明掺杂是个放热过程.掺杂纳米管的能隙远小于纯纳米管能隙.计算结果表明Mn掺杂纳米管趋于反...采用第一性原理密度泛函理论系统地研究Mn原子单掺杂和双掺杂ZnS纳米管的结构、电子性质和磁性质.掺杂纳米管的形成能比纯纳米管形成能更低,表明掺杂是个放热过程.掺杂纳米管的能隙远小于纯纳米管能隙.计算结果表明Mn掺杂纳米管趋于反铁磁态.为了获得室温铁磁性,用一个C原子替代一个S原子.发现铁磁态能量比反铁磁态能量低0.454 e V.如此大的能量差表明这类材料中有可能获得室温铁磁性.展开更多
文摘The cobalt ferrite nanoparticles were prepared by coprecipitation in the presence of poly (N-vinylpyrrolidone) (PVP) and characterized by XRD, TEM, EDX and magnetometry. XRD results suggest the formation of pure cobalt ferrite. The mean particle sizes of CoFe2O4 samples annealed at 400 ℃ and 600 ℃ were ca. 6 and 25 nm, respectively as obtained by transmission electron microscopy (TEM). The magnetic measurements indicated that nano-particles obtained at 400 ℃ were superparamagnetic while that prepared at 600 ℃ were ferrimagnetic.
文摘运用密度泛函理论的第一性原理计算分析了MgZn2相的电子结构及相关磁性质。能带结构和态密度分析表明Zn4s和Zn4p轨道、Mg3s和Mg3p轨道分别发生sp态杂化,然后杂化态之间相互作用而形成Zn-Mg键;Mulliken布居分布计算显示:Zn1-Mg(Zn1是处于晶格边缘的Zn原子)和Zn2-Mg(Zn2是处于晶格内部的Zn原子)电子云重叠布居数接近0,电子密度分析显示Zn-Mg之间电子密度分布具有明显的定域性。结合上述结果与Zn、Mg原子的电负性差异,确定Zn-Mg键为极性共价键。分态密度(PDOS)分析显示,Zn1-Mg键和Zn2-Mg键的差异主要表现在Zn24s轨道在-10^-6 e V区域对成键的贡献度高于Zn14s轨道,而Zn14s轨道在2~5 e V区域对成键的贡献度高于Zn24s轨道。进一步对MgZn2的积分自旋态密度和磁矩计算表明:MgZn2磁性质表现为顺磁性,其磁性主要来源于Zn1-Mg键中的2个自旋相同的未配对电子;MgZn2的顺磁性特性将使Al-Zn-Mg-Cu(7×××系)高强铝合金产生磁致塑性效应。
文摘A new cyano bridged assembly,2·5H2O, prepared by slow diffusion of an aqueous solution of K2 and an aqueous solution of ClO4 in an U tube, has been characterized by X ray structure analysis, IR and magnetic measurements. The crystal crystallizes in orthorhombic, space group Pnna, a=2.8189(5)nm, b=0.8407(2)nm, c=1.4554(2)nm, V= 3.4491(11)nm3 and Z=4. The complex is built up of infinite chains which are formed by trans Ni(en)2 μ (NC)2, cis μ (NC)2Ni(CN)2 and cis μ (CN)2Ni(en)2 groups. The variable temperature magnetic susceptibility has been measured in the 5～300K range. A magnetic susceptibility study indicates the presence of a weak antiferromagnetic interaction and gives it’s weiss constant θ=2.6K. CCDC: 207329.
基金Supported by the Natural Science Foundation of China(11404279,11247235,11547263)Qinglan Project of Jiangsu Province
文摘采用第一性原理密度泛函理论系统地研究Mn原子单掺杂和双掺杂ZnS纳米管的结构、电子性质和磁性质.掺杂纳米管的形成能比纯纳米管形成能更低,表明掺杂是个放热过程.掺杂纳米管的能隙远小于纯纳米管能隙.计算结果表明Mn掺杂纳米管趋于反铁磁态.为了获得室温铁磁性,用一个C原子替代一个S原子.发现铁磁态能量比反铁磁态能量低0.454 e V.如此大的能量差表明这类材料中有可能获得室温铁磁性.
