The Defect Chemistry of LaMnO3±δ

Roosmalen, J.A.M. van; Cordfunke, E.H.P.; Helmholdt, R. B.; Zandbergen, H.W.

doi:10.1006/jssc.1994.1141

Cited by 357 publications

(180 citation statements)

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“…However it is interesting to note that the enthalpies obtained for x=0.3 after the first and the second titrations are near each other, suggesting a smaller dependence of the 2 O H Δ on the oxygen stoichiometry change at higher departure from stoichiometry. This result tends to agree with the assumption that metal vacancies prevail, since a value for enthalpy which is independent of nonstoichiometry is expected for randomly distributed and noninteracting metal vacancies (van Roosmalen, 1994;Tanasescu, 2005). The model based on excess oxygen compensated by cation vacancies and partial charge disproportionation of manganese ions was also proposed for other related systems, like LaMnO 3+δ (van Rosmallen, 1995;Töpfer, 1997), BiMnO 3+δ (Sundaresan, 2008), BiFe 0.7 Mn 0.3 O 3+δ (Kundu, 2008).…”

Section: Phase Composition and Crystalline Structuresupporting

confidence: 75%

Effects of Doping and Oxygen Nonstoichiometry on the Thermodynamic Properties of Some Multiferroic Ceramics

Tănăsescu¹,

Botea²,

Ianculescu³

2011

Ferroelectrics - Physical Effects

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Section: Phase Composition and Crystalline Structuresupporting

confidence: 75%

Effects of Doping and Oxygen Nonstoichiometry on the Thermodynamic Properties of Some Multiferroic Ceramics

Tănăsescu¹,

Botea²,

Ianculescu³

2011

Ferroelectrics - Physical Effects

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“…The excess oxygen is accounted by an equal number of vacancies at A and B sites of ABO 3 perovskites while the oxygen network in believed to be undefected. 26 As said earlier, investigations of low-doped manganites have revealed the formation of orbital domain state in the ferromagnetic insulating regimes. 7,10 Increasing non stoichiometry, increases the Mn 4+ content resulting in suppression of the OO phase with the clusters becoming more populous eventually coalescing leading to the establishment of homogeneous ferromagnetic order.…”

Section: Introductionmentioning

confidence: 99%

Changeover from glassy ferromagnetism of the orbital domain state to long-range ferromagnetic ordering inLa0.9Sr0.1MnO3

Mukherjee

Banerjee

2008

Phys. Rev. B

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An attempt is made to resolve the controversy related to the low temperature phase (ground state) of the low-doped ferromagnetic (FM)-insulator(I) manganite through bulk magnetic measurements on La0.9Sr0.1MnO3 sample. It is shown that the FM phase, formed out of well defined transition in the low-doped system, becomes inhomogeneous with decrease in temperature. This inhomogeniety is considered to be an outcome of the formation of orbital domain state of eg-electrons having hole rich (metallic) walls separating the hole deficient (insulating) regions. The resulting complexity brings in metastability and glassy behaviour within the FM phase at low temperature, however, with no resemblance to spin glass, cluster glass or reentrant phases. It shows ageing effect without memory but magnetic relaxation shows signatures of inter-cluster interaction. The energy landscape picture of this glassy phase is described in terms of hierarchical model. Further, it is shown that this inhomogeneity disappear in La0.9Sr0.1MnO3.08 where, the orbital domain state is destroyed by self doping resulting in reduction of Mn 3+ and hence eg-electrons. The ferromagnetic phase of the nonstoichiometric sample, does not show glassy behaviour. It neither follows 'hierarchical model' nor 'droplet model' generally used to explain glassy or inhomogeneous systems. Its magnetic response can be explained simply from the domain wall dynamics of otherwise homogeneous ferromagnet.

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“…When the concentration of Mn 4+ ions increases, there is a corresponding increase in the oxygen content, so the La 0.9 Ba 0.1 MnO 3 formula can be written as La 0.9 Ba 0.1 MnO 3+δ (where δ indicates the excess oxygen). Van Roosmalen et al [23] concluded that the randomly distributed cation vacancies in equal amounts in perovskites lattice is responsible for excess oxygen in hole doped manganites. The Mn 4+ content in combustion derived LBMO samples was estimated from the iodometric titration [24] and it is found that the Mn 4+ content is 36 and 32% for as-formed and calcined samples, respectively.…”

Section: Effect Of Mn 4+ Contentmentioning

confidence: 99%

Magnetoresistance studies on barium doped nanocrystalline manganite

Nagabhushana

Chakradhar

Ramesh

et al. 2008

Journal of Alloys and Compounds

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An energetically attractive, simple, fast and a novel low temperature (300• C) solution combustion route for the synthesis of crystalline and homogeneous nanoparticles of lanthanum barium manganese oxide La 0.9 Ba 0.1 MnO 3+δ (LBMO) is reported. Formation and homogeneity of the solid solutions have been confirmed by powder X-ray diffraction (PXRD) and energy dispersive X-ray analysis (EDS) respectively. The Rietveld analysis shows both as-formed as well as calcined samples are in cubic phase with space group pm3m. The microstructure and agglomerated particle size of the compounds are examined by scanning electron microscope. Infrared spectroscopy revealed that both Mn O Mn bending mode and Mn O stretching mode are influenced by calcination temperature. The magnetoresistance measurement on sintered LBMO pellet exhibits a broad metal-insulator transition (T M-I ) at around 228 K. At 1 T applied magnetic field, LBMO shows magnetoresistance (MR) of 10%, whereas for 4 and 7 T, the negative magnetoresistance values are in the range 51 and 59% respectively at T M-I . The experimental resistivity data of the present investigation are fitted to a simple empirical equation in order to understand conduction mechanism in this compound.

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The Defect Chemistry of LaMnO3±δ

Cited by 357 publications

References 0 publications

Effects of Doping and Oxygen Nonstoichiometry on the Thermodynamic Properties of Some Multiferroic Ceramics

Effects of Doping and Oxygen Nonstoichiometry on the Thermodynamic Properties of Some Multiferroic Ceramics

Changeover from glassy ferromagnetism of the orbital domain state to long-range ferromagnetic ordering inLa0.9Sr0.1MnO3

Magnetoresistance studies on barium doped nanocrystalline manganite

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