Neutron diffraction study of Pr0.5Ca0.5CoO3-γ(γ=0 and 0.07)

Chichev, A.; Dlouhá, M.; Vratislav, S.; Hejtmánek, J.; Jirák, Z.; Knı́žek, K.; Maryško, M.

doi:10.1524/zksu.2007.2007.suppl_26.435

Cited by 11 publications

(3 citation statements)

References 5 publications

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“…7(a) we may mention that the T MI vs r A relation is applicable only for the (Pr 1−y RE y ) 0.7 Ca 0.3 CoO 3 systems and does not hold for the intensively studied system Pr 0.5 Ca 0.5 CoO 3−δ , in which the Co, Pr valences and T MI strongly depend on the actual oxygen content. 4,7,17,29,30 Finally, in Fig. 7(b derived systems are prepared generally as stoichiometric ones, as proved for selected samples by thermogravimetry or neutron diffraction method.…”

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confidence: 99%

Simultaneous valence shift of Pr and Tb ions at the spin-state transition in (Pr1−yTby)0.7

et al. 2013

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Temperature dependence of the X-ray absorption near-edge structure (XANES) spectra at the Pr L 3 -and Tb L 3 -edges was measured for the (Pr 1−y Tb y ) 0.7 Ca 0.3 CoO 3 system, in which a metalinsulator (MI) and spin-state (SS) transition took place simultaneously at a critical temperature T MI . A small increase in the valence of the terbium ion was found below T MI , besides the enhancement of the praseodymium valence; the trivalent states, which are stable at room temperature, change to a 3+/4+ ionic mixture at low temperatures. In particular for the y=0.2 sample, the average valence determined at 8 K amounts to 3.25+ and 3.03+ for the Pr and Tb ion, respectively.In analogous (Pr 1−y RE y ) 0.7 Ca 0.3 CoO 3 samples (RE=Sm and Eu), in which the MI-SS transition also took place, no valence shift of the RE ion was detected in the XANES spectra at the RE ion L 3 -edge. The role of the substituted RE ion for the Pr-site on the MI-SS transition is discussed.

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confidence: 99%

Simultaneous valence shift of Pr and Tb ions at the spin-state transition in (Pr1−yTby)0.7

et al. 2013

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“…Note that anion-deficient Pr 0.5 Ca 0.5 CoO 3Àd exhibits macroscopic structural phase separation into ferromagnetic and nonmagnetic phases. 39 In this case, unit cell volume is too small to stabilize Co 3þ ion in high spin state. Spin state transition in "stoichiometric" Pr 0.5 Ca 0.5 CoO 3 is assisted by partial excitation of Pr 3þ ½15ð65Þ% into Pr 4þ ions.…”

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Very large magnetoresistance and spin state transition in Ba-doped cobaltites

Troyanchuk

Bushinsky

Nikitin

et al. 2013

Journal of Applied Physics

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Structural, magnetization, and magnetotransport measurements have been performed for anion deficient La 0.5 Ba 0.5 Co 1Àx Fe x O 3Àd (x 0:4) and La 1Ày Ba y CoO 3Àd (0:5 y 0:6) perovskites. It has been found that the iron doped compositions with x 0:23 are predominantly ferromagnetic. The Curie point and magnetization are slightly larger in insulating phase (x ¼ 0.1) than in metallic one (x ¼ 0.05). Magnetoresistance ratio rises with lowering temperature and increasing iron content reaching three orders of magnitude in predominantly antiferromagnetic state (x ! 0:2 5) .T h er i s eo ft h eb a r i u m content in La 1Ày Ba y CoO 3Àd series above y ¼ 0.5 leads to stabilization of antiferromagnetic phase and strong enhancement of the magnetoresistance. Antiferromagnetic ordering is accompanied by increase in resistivity. The lack of the low field intergrain magnetoresistance is in agreement with a weak spin polarization of the charge carriers. Magnetoresistance is associated with antiferromagnet-ferromagnet (from mixed high/low into intermediate spin state) transition induced by magnetic field. It is suggested that ferromagnetism is originated from superexchange interaction via oxygen. V

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“…7, 9 that the transition can be caused by partial ordering of Co ions being in intermediate spin state. The other possible explanation of the feature at T A is a spin state transition of Co 3+ ions into low spin state with temperature decrease 10. A 2f–2p hybridization of praseodymium and oxygen ions have also been proposed to explain the magnetic transition at T A 8.…”

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Magnetic peculiarity and crystal structure of Pr_0.5 Sr_0.5 Co_1−x Fe_x O₃

Karpinsky

Troyanchuk²,

Chobot

et al. 2009

phys. stat. sol. (b)

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Crystal structure and magnetic properties of the Pr 0.5 Sr 0.5 Co 1Àx Fe x O 3Àd are studied to clarify an origin of the magnetic peculiarity observed for Pr 0.5 Sr 0.5 CoO 3Àd compound near T A % 120 K. A correlation between crystal symmetry, magnetic structure, and the magnetic anomaly is discussed. At room temperature the compounds with x < 0.67 have orthorhombic crystal structure described by Imma space group. Crystal symmetry of these compounds reduces down to monoclinic (triclinic) one with a temperature decrease, whereas the crystal structure of the solid solutions with x > 0.7 remains orthorhombic at low temperatures. Increase of Fe percentage changes the magnetic properties of the compounds from ferromagnetic to cluster spin-glass, spin glass and then to antiferromagnetic one. An existence of the magnetic feature is strongly dependent on the magnetic state of the compounds. The data obtained specify that a rearrangement of the bond lengths in rare-earth sublattice is responsible for the crystal structure modification and thus for the magnetic anomaly.

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Neutron diffraction study of Pr_0.5Ca_0.5CoO_3-γ(γ=0 and 0.07)

Cited by 11 publications

References 5 publications

Simultaneous valence shift of Pr and Tb ions at the spin-state transition in (Pr1−yTby)0.7

Simultaneous valence shift of Pr and Tb ions at the spin-state transition in (Pr1−yTby)0.7

Very large magnetoresistance and spin state transition in Ba-doped cobaltites

Magnetic peculiarity and crystal structure of Pr_0.5 Sr_0.5 Co_1−x Fe_x O₃

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Neutron diffraction study of Pr0.5Ca0.5CoO3-γ(γ=0 and 0.07)

Cited by 11 publications

References 5 publications

Simultaneous valence shift of Pr and Tb ions at the spin-state transition in (Pr1−yTby)0.7

Simultaneous valence shift of Pr and Tb ions at the spin-state transition in (Pr1−yTby)0.7

Very large magnetoresistance and spin state transition in Ba-doped cobaltites

Magnetic peculiarity and crystal structure of Pr0.5 Sr0.5 Co1−x Fe x O3

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Neutron diffraction study of Pr_0.5Ca_0.5CoO_3-γ(γ=0 and 0.07)

Magnetic peculiarity and crystal structure of Pr_0.5 Sr_0.5 Co_1−x Fe_x O₃