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中国物理学会期刊

非化学计量配比La0.67Sr0.33-x□xMnO3的结构和输运性质的研究

CSTR: 32037.14.aps.58.378

Study on structural and transport properties of nonstoichiometric La0.67Sr0.33-x□xMnO3

CSTR: 32037.14.aps.58.378
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  • 利用固相反应法制备了非化学计量配比的类钙钛矿锰氧化物La0.67Sr0.33-x□xMnO3(0x≤0.33),研究了A位空位对材料的晶体结构和输运性质的影响.对粉末X射线衍射谱的Rietveld全谱拟合表明样品均为单相,在x=0到x=0.33空位浓度范围内晶体对称性没有发生变化,均具有三方对称性,空间群为R3c<

     

    In this article,hole-doped nonstoichiometric manganites La0.67Sr0.33-x□xMnO3 (x=0,0.05,0.1,0.15,0.2,0.25,0.3,0.33) with A-site vacancy were synthesized using the solid-state reaction technique and the effect of A-site vacancy on structure and transport properties were studied. Results from Rietveld refinement of powder X-ray diffraction patterns showed that all samples were single phase with space group R3c and there were no structural phase transition for vacancy content x ranging from 0 to 0.33. The lattice parameters and volume of unit cell vary distinctly with x. These variations maybe result from the uncertain occupation ratio of vacancies at A-sites and Mn-sites. The bond angle of Mn—O—Mn decreases with increasing x,which indicates the presence of further distortion of MnO6 octahedron. Electrical measurements of La0.67Sr0.33-x□xMnO3 showed that the samples exhibited a metallic-insulator phase transition for xTMI towards higher temperature. In the range of 0.25≤x≤0.33,the samples exhibit insulating behavior without metallic-insulator transition,and also the effect of the magnetic field is to lower the resistivity.

     

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