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Title
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double perovskite : an antipolar anti-ferromagnet
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Author
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Abstract
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| Pb2MnTeO6, a new double perovskite, was synthesized. Its crystal structure was determined by synchrotron X-ray and powder neutron diffraction. Pb2MnTeO6 is monoclinic (I2/m) at room temperature with a regular arrangement of all the cations in their polyhedra. However, when the temperature is lowered to similar to 120 K it undergoes a phase transition from I2/m to C2/c structure. This transition is accompanied by a displacement of the Pb atoms from the center of their polyhedra due to the 6s2 lone-pair electrons, together with a surprising off-centering of Mn2+ (d5) magnetic cations. This strong first-order phase transition is also evidenced by specific heat, dielectric, Raman, and infrared spectroscopy measurements. The magnetic characterizations indicate an anti-ferromagnetic (AFM) order below TN approximate to 20 K; analysis of powder neutron diffraction data confirms the magnetic structure with propagation vector k = (0 1 0) and collinear AFM spins. The observed jump in dielectric permittivity near similar to 150 K implies possible anti-ferroelectric behavior; however, the absence of switching suggests that Pb2MnTeO6 can only be antipolar. First-principle calculations confirmed that the crystal and magnetic structures determined are locally stable and that anti-ferroelectric switching is unlikely to be observed in Pb2MnTeO6. |
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Language
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English
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Source (journal)
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Inorganic chemistry / American Chemical Society. - Easton, Pa
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Publication
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Easton, Pa
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2016
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ISSN
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0020-1669
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DOI
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10.1021/ACS.INORGCHEM.6B00054
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Volume/pages
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55
:9
(2016)
, p. 4320-4329
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ISI
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000375519700027
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Pubmed ID
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27058393
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Full text (Publisher's DOI)
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Full text (publisher's version - intranet only)
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