High-Temperature Dielectric Permittivity Characterization of Curie’s Temperature Shifting and Correlation with the Changing Dielectric Loss in a Semiconductor Ferroelectric

Reference	Presenter	Authors (Institution)	Abstract
08-096	Marcos Augusto Lima Nobre	Nobre, M.A.(Faculdade de Ciências e Tecnologia); Praxedes, F.R.(Faculdade de Ciências e Tecnologia); Bellucci, F.S.(Ministério da Ciência, Tecnologia e Inovação); Lanfredi, S.(Faculdade de Ciências e Tecnologia);	The loss of magnitude of niobium off-center has been induced by selective doping, in fact a non-isovalent doping at niobium site of the KSr2Nb5O15 host structure of polar tetragonal tungsten bronze TTB-type structure. A set of single phase ferroelectric niobates based on the nickel-doped KSr2Nb5O15 solid solution were prepared. In these materials, the transition ferroelectric-paraelectric is gradual at around Curie’s temperature. Then, non-symmetry correlated phase-transition phenomenon were investigated by both dielectric spectroscopy, in the temperature range from room temperature up to 700 K. The ferroelectric-paraelectric phase transition is characterized by the shifting of Curie’s Temperature at low temperature domain. The magnitude of the Nb off-center displacement and its correlation with the Curie’s Temperature was revisited. An innovative tools based on the both dielectric spectroscopy and dielectric loss spectroscopy was applied to derive the Curie’s Temperature and investigated the structural thermal stability of nickel-doped KSr2Nb5O15 solid solutions. The structural softening phenomenon is discussed via direct comparison between structural and dielectric parameter loss tangent.
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