CAJ | 학술논문

采用固相反应法制备了Nd_(0.5)Sr_(0.5)Co_(1-x)Mn_xO_3多晶样品(0≤x≤1).利用X射线衍射仪和Rietveld方法精修程序分析了样品的晶体结构;对样品的磁性和电输运性能进行了测量.结果表明:样品均为斜方晶系单相结构,空间群为Imma.样品的晶格常数a、b、c,晶格平均扭曲率D和有效磁矩μeff随着Mn含量x的增加而增大,促使Co离子向高自旋态转变.在x≥0.6时,样品中Co离子都处于高自旋态.在样品中,Mn替代了Co,Mn-O-Co的反铁磁性超交换作用与Co~(3+)-O~(2-)-Co~(4+)的铁磁性双交换作用相互竞争破坏了样品的金属导电行为,致使当x≥0.2时,样品表现出半导体导电行为.
채용고상반응법제비료Nd_(0.5)Sr_(0.5)Co_(1-x)Mn_xO_3다정양품(0≤x≤1).이용X사선연사의화Rietveld방법정수정서분석료양품적정체결구;대양품적자성화전수운성능진행료측량.결과표명:양품균위사방정계단상결구,공간군위Imma.양품적정격상수a、b、c,정격평균뉴곡솔D화유효자구μeff수착Mn함량x적증가이증대,촉사Co리자향고자선태전변.재x≥0.6시,양품중Co리자도처우고자선태.재양품중,Mn체대료Co,Mn-O-Co적반철자성초교환작용여Co~(3+)-O~(2-)-Co~(4+)적철자성쌍교환작용상호경쟁파배료양품적금속도전행위,치사당x≥0.2시,양품표현출반도체도전행위.
Nd_(0.5)Sr_(0.5)Co_(1-x)Mn_xO_3 (0≤x≤1) polycrystal were prepared by the solid state reaction method. The crystal structure of obtained samples was studied with XRD and Rietveld refinement program. The magnetic and electro transport properties of obtained samples were also investigated. The results show that all the samples exhibit single-phase orthorhombic structure (Imma). The lattice constants a, b, c, average ratio of crystal lattice distortion D and effective magnetic moment μeff of samples increase with increasing Mn content, promoting Co ions transforming into high-spin state. All the Co ions are in high-spin state when x≥0.6. In the Nd_(0.5)Sr_(0.5)Co_(1-x)Mn_xO_3 samples, Co is substituted by Mn, and the antiferromagnetic super-exchange interaction of Mn-O-Co competes with the ferromagnetic double-exchange interaction of Co~(3+)-O~(2-)-Co~(4+), resulting in the worsening of metallic behavior of samples. The samples exhibit semiconductor behavior when x≥0.2.