High pressure synthesis and properties of Bi{sub 0.5}Pb{sub 0.5}CrO{sub 3}: A novel Cr{sup 4+}/Cr{sup 3+} perovskite

Journal Article · Fri May 15 00:00:00 EDT 2015 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2014.10.027· OSTI ID:22475611

Pirrotta, Ivan ^[1]; Schmidt, Rainer ^[2]; Dos Santos-García, Antonio J. ^[1]; Garcia-Hernandez, Mar ^[3]; Morán, Emilio ^[1]; others, and

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1. Dpto. Química Inorgánica, Facultad de CC. Químicas, Universidad Complutense de Madrid, 28040 Madrid (Spain)
2. Dpto. Física Aplicada III, Facultad de CC. Físicas, GFMC, Universidad Complutense de Madrid, 28040 Madrid (Spain)
3. Instituto de Ciencias de Materiales de Madrid—Consejo Superior de Investigaciones Cientìficas (ICMM-CSIC), Sor Juana Inés de la Cruz, 3, Cantoblanco, E-28049 Madrid (Spain)

We have synthesized a new Bi{sub 0.5}Pb{sub 0.}5CrO{sub 3} perovskite phase by means of a high pressure reaction at 70 kbar and 1000 °C. The distorted orthorhombic perovskite structure can be indexed in the space group Pnma with lattice parameters a=5.4768 (1) Å, b=7.7450 (2) Å, and c=5.4574 (1) Å at room temperature, but undergoes a structural phase transition and enters into a P2{sub 1}/m monoclinic distorted perovskite phase below 150 K with a=5.4173 (2), b=7.7286 (4) and c=5.4930 (3). The structural transition is coincident with the onset of magnetic interactions. At lower temperatures a weak ferromagnetic structure is evident related to antiferromagnetic Cr-spin canting and a spin-glass transition is observed at ≈40 K. The semiconducting-type electrical resistivity is relatively low, associated with Cr{sup 3+}/Cr{sup 4+} electron hopping, and shows considerable magneto-resistance (up to 15%). Due to the low resistivity the dielectric permittivity ε{sub r} could be determined only below T<80 K to be ≈300 and did not show any strong temperature-dependence. Ferroelectricity was not detected in the T-range investigated and no magnetocapacitance effects were observed. - Graphical abstract: A new Bi{sub 0.5}Pb{sub 0.}5CrO{sub 3} perovskite phase has been synthesized under high pressure (70 kbar) and high temperature (1000 °C) conditions. The room temperature structure is orthorhombic and can be indexed in the space group Pnma but below 150 K undergoes a structural phase transition and enters into a P2{sub 1}/m monoclinic distorted perovskite phase. The structural transition is coincident with the onset of magnetic interactions. Mott variable-range hopping charge transport and magnetoresistance effects are evident. - Highlights: • A new Bi{sub 0.5}Pb{sub 0.}5CrO{sub 3} perovskite has been synthesized under HP/HT conditions. • An orthorhombic-to monoclinic phase transition takes place at 150 K. • The structural transition is coincident with the onset of magnetic interactions. • Mott variable-range hopping charge transport and magnetoresistance are evident.

• OSTI ID: 22475611
• Journal Information: Journal of Solid State Chemistry, Vol. 225; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANTIFERROMAGNETISM
BISMUTH COMPOUNDS
CHARGE TRANSPORT
CHROMATES
CHROMIUM IONS
CHROMIUM OXIDES
DIELECTRIC MATERIALS
LATTICE PARAMETERS
LEAD COMPOUNDS
MAGNETIC PROPERTIES
MAGNETORESISTANCE
MONOCLINIC LATTICES
ORTHORHOMBIC LATTICES
PERMITTIVITY
PEROVSKITE
PHASE TRANSFORMATIONS
SPIN GLASS STATE
SYNTHESIS
TEMPERATURE DEPENDENCE