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Nanocrystalline Barium Strontium Titanate Ceramics Synthesized via the “Organosol” Route and Spark Plasma Sintering
Author(s) -
Gao Yanling,
Shvartsman Vladimir V.,
Gautam Devendraprakash,
Winterer Markus,
Lupascu Doru C.
Publication year - 2014
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12933
Subject(s) - materials science , nanocrystalline material , spark plasma sintering , dielectric , ceramic , barium titanate , grain size , curie temperature , ferroelectricity , permittivity , analytical chemistry (journal) , mineralogy , atmospheric temperature range , composite material , nanotechnology , optoelectronics , condensed matter physics , meteorology , chemistry , physics , chromatography , ferromagnetism
Dense nanocrystalline barium strontium titanate Ba 0.6 Sr 0.4 TiO 3 ( BST ) ceramics with an average grain size around 40 nm and very small dispersion were obtained by spark plasma sintering at 950°C and 1050°C starting from nonagglomerated nanopowders (~20 nm). The powders were synthesized by a modified “Organosol” process. X‐ray diffraction ( XRD ) and dielectric measurements in the temperature range 173–313 K were used to investigate the evolution of crystal structure and the ferroelectric to paraelectric phase transformation behavior for the sintered BST ceramics with different grain sizes. The Curie temperature T C decreases, whereas the phase transition becomes diffuse for the particle size decreasing from about 190 to 40 nm with matching XRD and permittivity data. Even the ceramics with an average grain size as small as 40 nm show the transition into the ferroelectric state. The dielectric permittivity ε shows relatively good thermal stability over a wide temperature range. The dielectric losses are smaller than 2%–4% in the frequency range of 100 Hz–1 MHz and temperature interval 160–320 K. A decrease in the dielectric permittivity in nanocrystalline ceramics was observed compared to submicrometer‐sized ceramics.