Structure, magnetism, specific heat, and dielectric properties of Eu{sub 2}Ta{sub 2}O{sub 7}

Journal Article · Mon Nov 17 00:00:00 EST 2014 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4902345· OSTI ID:22392028

Sakurai, H.; Matsushita, Y. ^[1]

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1. National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan)

Polycrystalline Eu{sub 2}Ta{sub 2}O{sub 7} containing layered perovskite slabs was prepared and analyzed. Eu{sub 2}Ta{sub 2}O{sub 7} crystallizes in the orthorhombic centrosymmetric Cmcm space group (with unit cell: a = 3.95156(9), b = 27.0775(6), and c = 5.68279(13) Å) isomorphous with high-temperature Sr{sub 2}Ta{sub 2}O{sub 7}. Dielectric measurements reveal that, in contrast to Sr{sub 2}Ta{sub 2}O{sub 7} which is ferroelectric below 166 K, Eu{sub 2}Ta{sub 2}O{sub 7} remains paraelectric down to at least 0.45 K and shows no magneto-dielectric coupling. Magnetic data in the 2–400 K range indicate an antiferromagnetic phase transition with a sharp susceptibility peak at 2.71(5) K. Further analysis using specific heat measurements reveals that the second magnetic phase transition occurs at 1.10(5) K and dominates the spin entropy of the Eu{sup 2+} 4f{sup 7} ions. The possible origin of the two successive magnetic phase transitions in Eu{sub 2}Ta{sub 2}O{sub 7} requires further studies.

• OSTI ID: 22392028
• Journal Information: Applied Physics Letters, Vol. 105, Issue 20; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANTIFERROMAGNETISM
DIELECTRIC PROPERTIES
ENTROPY
EUROPIUM COMPOUNDS
EUROPIUM IONS
FERROELECTRIC MATERIALS
ORTHORHOMBIC LATTICES
PEROVSKITE
PHASE TRANSFORMATIONS
POLYCRYSTALS
SPACE GROUPS
SPECIFIC HEAT
SPIN
STRONTIUM COMPOUNDS
TANTALATES