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AbstractAbstract
[en] Plate-like Ca_3Ti_2O_7 (CT) and Nd_2Ti_2O_7 (NT) particles were synthesized in molten salts and used as reactive templates for the preparation of highly textured (Ca_0_._7Nd_0_._3)_0_._8_7TiO_3 bulk ceramics (CNT) with preferred pseudocubic 〈100〉 and 〈110〉 orientations, respectively. During flux growth CT and NT particles developed facets parallel to the pseudocubic {100} and {110} planes, respectively, in a perovskite unit cell, since those planes correspond to the interlayers of the layered perovskite-type crystal structures. Complementary reactants for the CNT stoichiometry were wet-mixed with the reactive templates and the slurries were tape-cast. Then stacked tapes were heat-treated for dense single-phase CNT ceramics with a distorted and A-site deficient regular perovskite-type structure. The CNT ceramics prepared with CT and NT reactive templates exhibited strong pseudocubic 100- and 110-family x-ray diffraction peaks, respectively, with other peaks drastically suppressed when non-perovskite sources were used as complementary reactants. The textured ceramics possess unique microstructures; as either parallel or obliquely stacked block structures with a pseudocubic {100} plane faceted. The pseudocubic {100}-and {110}-textured CNT ceramics exhibited ∼10 and ∼20% higher products of the dielectric quality factor and frequency, Q · f, respectively, than conventional ceramic sintered at the same temperature. When Q · f is compared based on the same grain size, the {100}-textured CNT exhibited 27% higher values than non-textured while relative permittivity and temperature coefficient of resonant frequency were of similar values. Simple geometrical relationships between electric field and penetrated pseudocubic {hk0}-type grain boundaries must lead to the reduced scattering and dielectric loss. (paper)
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Source
Available from http://dx.doi.org/10.1088/1468-6996/16/3/035008; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Science and Technology of Advanced Materials; ISSN 1468-6996;
; v. 16(3); [10 p.]

Country of publication
CALCIUM COMPOUNDS, CERAMICS, COMPUTERIZED TOMOGRAPHY, CRYSTAL GROWTH, CRYSTAL STRUCTURE, DIELECTRIC MATERIALS, ELECTRIC FIELDS, GRAIN BOUNDARIES, GRAIN GROWTH, HEAT TREATMENTS, MICROWAVE RADIATION, NEODYMIUM COMPOUNDS, PERMITTIVITY, PEROVSKITE, QUALITY FACTOR, STOICHIOMETRY, TEMPERATURE COEFFICIENT, TITANATES, X RADIATION, X-RAY DIFFRACTION
ALKALINE EARTH METAL COMPOUNDS, COHERENT SCATTERING, DIAGNOSTIC TECHNIQUES, DIELECTRIC PROPERTIES, DIFFRACTION, DIMENSIONLESS NUMBERS, ELECTRICAL PROPERTIES, ELECTROMAGNETIC RADIATION, IONIZING RADIATIONS, MATERIALS, MICROSTRUCTURE, MINERALS, OXIDE MINERALS, OXYGEN COMPOUNDS, PEROVSKITES, PHYSICAL PROPERTIES, RADIATIONS, RARE EARTH COMPOUNDS, REACTIVITY COEFFICIENTS, SCATTERING, TITANIUM COMPOUNDS, TOMOGRAPHY, TRANSITION ELEMENT COMPOUNDS
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