Temperature dependences of the real part of the dielectric permittivity (a) and of the tangent of the dielectric losses measured on heating in ceramics at the frequencies 100 Hz, 1 kHz, 10 kHz, 100 kHz, and 500 kHz. The insets show temperature dependence of the dielectric permittivity and tangent of the dielectric losses measured on heating (solid symbols) and cooling (open symbols) at 500 kHz.
(a) P(E) hysteresis loops measured in ceramics at different temperatures on heating. Temperature dependences of remanent polarization measured on heating (solid symbols) and cooling (open symbols).
PFM images of ceramics taken on heating at (a) 295, (b) 335, (c) 350, and (d) 360 K (scan size ). Solid lines indicate grain boundaries.
Temperature dependences of the effective piezoresponse measured on heating and on cooling (line are drown to eye guidance). Inset shows a distribution of the piezoresponse signal measured at RT. This distribution is treated as a superposition of three Gaussian peaks: two polar peaks at and and one nonpolar centered at . Here is the local piezoresponse value.
PFM images of ceramics taken on cooling at (a) 360, (b) 315, and (c) 295 K (scan size ). Solid lines indicate grain boundaries.
Temperature evolution of the poled area in ceramics: (a) initial state; (b)–(d) after the area was scanned under −30 V: at (b) 295, (c) 335, and (d) 360 K.
Distribution of piezoresponse signal measured inside the poled area at different temperatures.
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