scholarly journals Индуцированный фазовый переход в монокристаллических твердых растворах PbMg-=SUB=-1/3-=/SUB=-Nb-=SUB=-2/3-=/SUB=-O-=SUB=-3-=/SUB=--29PbTiO-=SUB=-3-=/SUB=- и PbZn-=SUB=-1/3-=/SUB=-Nb-=SUB=-2/3-=/SUB=-O-=SUB=-3-=/SUB=--9PbTiO-=SUB=-3-=/SUB=-: сходство и различие

2021 ◽  
Vol 63 (11) ◽  
pp. 1880
Author(s):  
Л.С. Камзина
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Low Temperature ◽  
Electric Fields ◽  
Delay Time ◽  
Optical Transmission ◽  
Ferroelectric Phase ◽  
Morphotropic Phase Transition ◽  
Macroscopic Polarization ◽  
Kinetics Of

The kinetics of the induced phase transition in single-crystal relaxor solid solutions PbMg1 / 3Nb2 / 3O3-29PbTiO3 and PbZn1 / 3Nb2 / 3O3-9PbTiO3 is studied when an electric field is applied along the [001] direction. At temperatures below the temperature of the morphotropic phase transition, the changes in the dielectric constant and optical transmission in electric fields are studied. It is shown that the decrease in optical transmission with time is associated only with a change in the sizes of nanoregions during the phase transition. It was found that the induced phase transition proceeds differently in these crystals. In PMN-29PT crystals, the formation of ferroelectric phases and the rapid establishment of macroscopic polarization are preceded by a certain delay time, while in PZN-9PT crystals, the ferroelectric phase is induced immediately after the application of the field without a delay time. The results obtained are explained by the different structures of the low-temperature phases in these compounds. Key words: ferroelectricity, relaxors, induced phase transition.

scholarly journals Влияние концентрации La на кинетику индуцированного фазового перехода в прозрачной керамике PbMg-=SUB=-1/3-=/SUB=-Nb-=SUB=-2/3-=/SUB=-O-=SUB=-3-=/SUB=--25PbTiO-=SUB=-3-=/SUB=-

2020 ◽  
Vol 62 (4) ◽  
pp. 584
Author(s):  
Л.С. Камзина ◽  
G. Li
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Electric Fields ◽  
Optical Transmission ◽  
Ferroelectric Phase ◽  
Sharp Decrease ◽  
Polar Regions ◽  
Transparent Ceramics ◽  
The Stability ◽  
Over Time

The effect of La concentration on the kinetic nature of the induced phase transition in PbMg1/3Nb2/3O3–25PbTiO3 ferroceramics was studied. At temperatures below the Vogel-Fulcher temperature, the time-dependent changes in the dielectric constant and optical transmission in electric fields are studied 0 <E <6 kV / cm. It was found that in an electric field in La-containing transparent ceramics, a sharp decrease in the dielectric constant and optical transmission occurs over time, indicating an induced phase transition and an increase in the fraction of the ferroelectric phase. It has been shown that in undoped La ceramics the changes in the dielectric constant at the same fields are much smaller. It was found that the stability of the induced phase depends on the La concentration: the higher the concentration, the lower the stability. The results obtained are explained by both a varying degree of diffuse of the phase transition and different sizes of polar regions, which depend on the La concentration.

scholarly journals Поведение керамических твердых растворов 33PbYb-=SUB=-1/2-=/SUB=-Nb-=SUB=-1/2-=/SUB=-O-=SUB=-3-=/SUB=--22PbZrO-=SUB=-3-=/SUB=--45PbTiO-=SUB=-3-=/SUB=- в электрическом поле

2020 ◽  
Vol 46 (6) ◽  
pp. 31
Author(s):  
Л.С. Камзина ◽  
G. Li
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Electric Field ◽  
Electric Fields ◽  
Dielectric Parameters ◽  
Morphotropic Phase Transition ◽  
Temperature Dependences ◽  
Pseudocubic Phase

The temperature dependences of the dielectric parameters were studied, as well as the changes in the dielectric constant with time in ceramic 33PbYb1 / 2Nb1 / 2O3-22PbZrO3-45 PbTiO3 samples in electric fields (0 <E <8 kV / cm). It is shown that in the phase existing below the temperature of the morphotropic phase transition, in addition to the rhombohedral and tetragonal phases, a small fraction of the relaxor pseudocubic phase is present. It was found that, unlike other relaxors, the dielectric constant practically does not change with time when an electric field is applied in the phase below the temperature of the morphotropic phase transition. Possible reasons for this behavior are discussed.

Thermodynamics and kinetics of the phase transition ferroelectric smectic C* - nematic in electric fields

1993 ◽  
Vol 147 (1) ◽  
pp. 263-280 ◽  
Author(s):  
Sergel Pikin ◽  
Leonid Beresnev ◽  
Steffen Hiller ◽  
Wolfgang Haase
Keyword(s):  
Phase Transition ◽  
Electric Fields ◽  
Thermodynamics And Kinetics ◽  
Smectic C ◽  
Kinetics Of

Micro Mechanism of BaTiO3 Ferroelectric Phase Transition Described by Electron Cloud Model

2012 ◽  
Vol 479-481 ◽  
pp. 619-622
Author(s):  
Chao Fang ◽  
Liang Yan Chen
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Equilibrium Position ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Cloud Model ◽  
Electron Cloud ◽  
Oxygen Ions ◽  
Expansion Effect ◽  
Coulomb Attraction

In this paper the micro mechanism of BaTiO3 ferroelectric phase transition is studied based on the thermodynamic model using electron cloud model, and further the Curie - Weiss law is explained. The results indicate that the contraction of the electron cloud, as the temperature decreased through Curie temperature, causes oxygen ions shift the equilibrium position, and the Coulomb attraction makes Ti ion shift the equilibrium position causing phase transition; With temperature rising, the ion displacement polarization decreases owing to the electron cloud expansion effect, and the variation of dielectric constant with temperature follows the Curie - Weiss law.

scholarly journals Synthesis and characterization of lead-free ternary component BST–BCT–BZT ceramic capacitors

2014 ◽  
Vol 04 (02) ◽  
pp. 1450014 ◽  
Author(s):  
Venkata Sreenivas Puli ◽  
Dhiren K. Pradhan ◽  
Brian C. Riggs ◽  
Shiva Adireddy ◽  
Ram S. Katiyar ◽  
...  
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Energy Density ◽  
Electric Field ◽  
Hysteresis Loop ◽  
Electric Fields ◽  
Room Temperature ◽  
Thermal Hysteresis ◽  
Lead Free ◽  
Maximum Electric Field

Polycrystalline sample of lead-free 1/3( Ba 0.70 Sr 0.30 TiO 3) + 1/3( Ba 0.70 Ca 0.30 TiO 3) + 1/3( BaZr 0.20 Ti 0.80 O 3)( BST - BCT - BZT ) ceramic was synthesized by solid state reaction method. Phase purity and crystal structure of as-synthesized materials was confirmed by X-ray diffraction (XRD). Temperature-dependent dielectric permittivity studies demonstrated frequency-independent behavior, indicating that the studied sample has typical diffuse phase transition behavior with partial thermal hysteresis. A ferroelectric phase transition between cubic and tetragonal phase was noticed near room temperature (~ 330 K). Bulk P–E hysteresis loop showed a saturation polarization of 20.4 μC/cm2 and a coercive field of ~ 12.78 kV/cm at a maximum electric field of ~ 115 kV/cm. High dielectric constant (ε ~ 5773), low dielectric loss (tan δ ~ 0.03) were recorded at room temperature. Discharge energy density of 0.44 J/cm3 and charge energy density of 1.40 J/cm3 were calculated from nonlinear ferroelectric hysteresis loop at maximum electric field. Dielectric constant at variable temperatures and electric fields, ferroelectric to paraelectric phase transition and energy storage properties were thoroughly discussed.

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