【摘要】 用液相共沉淀法合成了La0.7Sr0.3Mn1-xRxO3(R=Co,Ni)样品。利用XRD对样品结构进行表征,结果表明,由于Co2+半径与Mn3+离子半径不匹配,当Co2+含量x>0.07时,样品La0.7Sr0.3Mn1-xCoxO3的结构由正交晶系向单斜晶系转变,而Ni2+离子半径与Mn3+离子半径相近,Ni的掺杂并没有改变系列样品La0.7Sr0.3Mn1-xNixO3的晶体结构。通过振动样品磁强计测试样品的磁性,结果表明,La0.7Sr0.3Mn1-xRxO3(R=Co,Ni)系列样品的比饱和磁化强度随掺杂浓度的增加而减少,这是由于Co2+和Ni2+取代Mn3+后,引起B位离子的电场差的减少,样品的稳定性降低,而使得比饱和磁化强度降低。更多还原

【Abstract】 La0.7Sr0.3Mn1-xRxO3(R=Co,Ni) powders were prepared by co-precipitation techniques.The structures of powder were characterized by X-ray diffraction.A orthorhombic-monoclinic transition of La0.7Sr0.3Mn1-xCoxO3 when x>0.07 was observed.This can be ascribe to dismatch radius between Co2+ and Mn3+.Meanwhile,the structure of La0.7Sr0.3Mn1-xNixO3 was not affected by the Ni doping for the ionic radio of Mn and Ni is similar.The magnetic properties were measured by VSM.It shows that the saturated magnetization of La0.7Sr0.3Mn1-xRxO3(R=Co,Ni) powders decrease with increase in dopant content x.It is suggested that it related to the substitution of Mn ion with Co2+ and Ni2+,which may decrease the difference of the B site electric field and weaken the stability of powders,so that the saturated magnetization was decreased.更多还原