Browsing by Author "Chang, Y. F."

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    Aging associated domain evolution in the orthorhombic phase of < 001 > textured (K0.5Na0.5)Nb0.97Sb0.03O3 ceramics
    Yao, Jianjun; Li, Jiefang; Viehland, Dwight D.; Chang, Y. F.; Messing, G. L. (AIP Publishing, 2012-03-01)
    Aging effect due to domain evolution in (K-0.5,Na-0.5)Nb0.97Sb0.03O3 < 001 > textured ceramics was investigated by piezoresponse force microscopy. We find that aging effect is pronounced in the orthorhombic single phase field. A more uniform and finer domain structure on the order of several hundred nanometers was observed after aging and is believed to originate from defect-migration. After poling, large domains (similar to 10 mu m) with smooth boundaries were found in the aged condition due to the more readily redistribution of uniform and finer domain structures after aging. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3698154]
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    Electric-field-dependent phase volume fractions and enhanced piezoelectricity near the polymorphic phase boundary of (K0.5Na0.5)(1-x)LixNbO3 textured ceramics
    Ge, Wenwei; Li, Jiefang; Viehland, Dwight D.; Chang, Y. F.; Messing, G. L. (American Physical Society, 2011-06-01)
    The structure, ferroelectric and piezoelectric properties of < 001 > textured (K0.5Na0.5)(0.98)Li0.02NbO3 ceramics were investigated as a function of temperature and dc bias E. X-ray diffraction revealed an orthorhombic (O) -> tetragonal (T) polymorphic phase boundary (PPB). Phase coexistence was found near the PPB over a 30 degrees C temperature range, where the relative phase volume fractions changed with temperature. Furthermore, increasing E applied along the < 001 > texture direction resulted in a notable increase in the volume fraction of the T phase at the expense of the O phase, effectively shifting the O -> T boundary to lower temperature. An enhancement in the piezoelectric properties was found to accompany this increase in the T volume fraction.