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摘要
The Griffiths phase has been investigated in terms of oxygen vacancy in polycrystalline samples La0.75Ca0.15MnO3 (LCMO-1) and La0.75Ca0.15MnO3-Delta (LCMO-2). The latter of the two samples is prepared by annealing the former (with existence of Griffiths phase) in N-2 atmosphere. Experimental results demonstrate that for the latter sample Griffith's phase disappears (according to its obeying Curie-Weiss law in the temperature dependence of inverse susceptibility) due to redistribution of magnetic disorder between Mn3+ and Mn4+ ions induced by the increment of crystal lattice structure parameters. XRD patterns of the two samples show an increase of crystal lattice structure parameters. X-ray absorption fine structure data manifest that the degree of structural disorder in LCMO-2 sample is higher than that of LCMO-1, indicating that local structural disorder in this system is not the key role to affect the existence of Griffiths phase, while magnetic distribution/disorder is an important character.
