多晶样品SrFe_(1-x)Mn_xO_(3-δ)的结构及电输运性质研究

Structural and Electrical Transport Properties of Polycrystal SrFe_(1-x)Mn_xO_(3-δ)

为了探讨钙钛矿型氧化物中Fe、Mn对其结构和电输运性质的影响,以具有不同氧含量的多晶SrFe1-xMnxO3-δ(x=0.00,0.11,0.22,0.33,0.66,0.88)样品为研究对象,通过XRD谱图精修、碘滴定法测定氧含量和用PPMS测低温电阻等分析手段,对此系列样品的结构和电输运性质进行了详细的分析.研究结果表明,组分范围为0≤x≤0.22的样品为氧空位有序的正交结构(空间群为Cmmm),Mn的进一步掺杂使其结构逐渐转变成另一种正交结构(空间群为Pmmm).除高温时的x=0.00样品外,其余样品的电输运都服从变程跳跃(VRH)导电机制,这表明体系为势无序体系,并且随着Mn掺杂量的增加,由Efros-Shklovskii型VRH过渡到Mott型VRH机制.

The effects of Fe and Mn ions on the structural and electrical transport properties of SrFe1-xMnxO3-δ（x=0.00,0.11,0.22,0.33,0.66,0.88） samples with different oxygen contents are studied by employing the refinement of XRD patterns,oxygen content measurement by iodometric titration and low temperature resistance measurement by PPMS.The results show that it possesses an oxygen vacancy ordering orthogonal structure（space group： Cmmm） when 0≤x≤0.22,and changes into another orthogonal structure（space group： Pmmm） with increasing Mn content.The temperature dependence of resistivity shows characteristic variable-range-hopping（VRH） mechanism for all samples except the high temperature part of x=0.00 sample, which means this system is disordered.With increasing Mn doping,the conduction mechanism changes from ES VRH to Mott VRH model.