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1.
It has been shown by using the statistical approach that the angular dependence of intensity I(θ) in multiple small-angle light scattering can be described by Lévy’s universal distribution functions. The fundamental property
of the stability of these distributions permits one to extract information on the characteristics of fractal media as complete
as it is possible in the simple single-scattering case. In particular, an analysis of the polarization characteristics of
I(θ) in disordered PST reveals that the surface fractals observed in these crystals are of the heterophase rather than domain
origin.
Fiz. Tverd. Tela (St. Petersburg) 40, 1537–1541 (August 1998) 相似文献
2.
L. S. Kamzina 《Physics of the Solid State》2016,58(12):2460-2464
The kinetics of electric field-induced nucleation of ordered ferroelectric phases from a mixed glassy relaxor state has been studied in a number of single-crystal (1–x)PbMg1/3Nb2/3O3–xPbTiO3 (PMN–xPT) solid solutions (x = 29, 33, 35%) lying in a morphotropic phase region. It is shown that the formation of these phases and fast establishment of a macroscopic polarization are preceded by some delay time, depending on the electric field strength and temperature. It is found that the monoclinic phase is thermodynamically stable at room temperature in all the compounds in the time (~3000 s) and electric field (~1 kV/cm) ranges under study, whereas the monoclinic phase of the compound with x = 35% transforms, at temperatures near the temperature of the morphotropic phase transition after insignificant time interval of ~100 s, to another stable ferroelectric tetragonal phase. 相似文献
3.
L. S. Kamzina E. V. Snetkova I. P. Raevski A. S. Emelyanov Jiayue Xu Weidong Xiang 《Physics of the Solid State》2007,49(4):762-768
The effect of a dc electric field on the nucleation and evolution of the phase with long-range order in a cubic nonpolar matrix
in 〈001〉-oriented (100 − x)PbMg1/3Nb2/3O3-xPbTiO3 single-crystal relaxors as the content of PbTiO3 is gradually increased (6 ≤ x ≤ 20, where x is the PbTiO3 content given in molecular percent) is investigated. The optical properties of these solid solutions are studied in different
modes of application of an electric field. It is shown that an applied electric field with a strength above a threshold value
induces a first-order ferroelectric phase transition with a temperature hysteresis occurring between measurements performed
under cooling and heating of the crystal in the electric field. As the PbTiO3 content or electric field strength increases, the hysteresis becomes less pronounced and the first-order phase transition
is suppressed. At x ∼ 20, the induced transition resembles a second-order rather than first-order transformation. It is assumed that, for compositions
with x > 10 in electric fields higher than 4 kV/cm, the formation of the rhombohedral phase is accompanied by the appearance of
another (possibly, monoclinic) phase associated with the rotation of the polarization vector from the [111] direction of the
rhombohedral phase to the [001] direction of the tetragonal phase.
Original Russian Text ? L.S. Kamzina, E.V. Snetkova, I.P. Raevskiĭ, A.S. Emel’yanov, Jiayue Xu, Weidong Xiang, 2007, published
in Fizika Tverdogo Tela, 2007, Vol. 49, No. 4, pp. 725–730. 相似文献
4.
The possibility of realizing a stable relaxor behavior in PbSc1/2Nb1/2O3 (PSN) compounds and the conditions favoring the formation of a phase with long-range order in PbZn1/3Nb2/3O3 (PZN) are studied using optical methods. It is found that the replacement of only 6% of Pb ions with Ba ions (PBSN-6) freezes the relaxor state in PSN compounds, while adding even 7% of PbTiO3 to the PZN relaxor (PZN-7PT) leads to the formation of a phase with long-range order and a phase transition occurring at T maxε through the percolation mechanism. Common features in the formation and destruction of the long-range order phase in relaxors of different types are revealed. The differences associated with the presence of spontaneously polarized ferroelectric regions in the cubic nonpolar matrix of PSN-type compounds are determined. 相似文献
5.
Physics of the Solid State - The time changes of permittivity, damping and velocity of sound are studied for PbFe0.5Nb0.5O3 and PbFe0.5Nb0.5O3–7PbTiO3 single crystals in the electric fields... 相似文献
6.
The processes of polarization evolution in single crystals of the PbMg1/3Nb2/3O3 model ferroelectric relaxor in a sinusoidal electric field are investigated at temperatures near and above the temperature T d 0 of destruction of the induced ferroelectric state upon heating in zero electric field. The polarization switching current loops are measured in the ac electric field applied along the 〈111〉 and 〈110〉 pseudocubic directions. The electroluminescence intensity loops are obtained under the combined action of ac and dc electric fields applied along the 〈100〉 direction. In a certain temperature range above T d 0 and the freezing temperature T f in lead magnesium niobate, there are electric current anomalies, that correspond to the dynamic formation and subsequent destruction of the ferroelectric macroregions throughout each half-cycle of the ac electric field. The measurements of electroluminescence hysteresis loops demonstrate that the observed depolarization delay (related to the ac electric field amplitude) increases with an increase in the dc electric field and decreases as the ac field amplitude increases. The nature of the observed phenomena is discussed. 相似文献
7.
L. S. Kamzina 《Physics of the Solid State》2017,59(9):1778-1782
Phase transformations in [111]- and [001]-oriented PbMg1/3Nb2/3O3–29PbTiO3 single crystals have been studied using dielectric and optical measurements before and after applying an electric field. It is shown that the subsequence of phase transitions rhombohedral (R)—tetragonal (T)—cubic (C) phases is observed in nonpolarized samples of both orientations as temperature increases. In the [111]-oriented crystal, an additional intermediate monoclinic phase (it is possible, M a ) is induced after preliminary polarization at room temperature and the R–M a –T–C phase transitions are observed on heating. In the [001]-oriented crystal, after its polarization, the monoclinic phase forms instead of the rhombohedral phase even at room temperature and the M a –T–C transitions occur on heating. The results are discussed from the point of view of the existence polar nanoregions with different local symmetries in a glasslike matrix. 相似文献
8.
Physics of the Solid State - The polarization kinetics in a transparent Pb(Mg1/3Nb2/3)O3–23Pb(Zr0.53Ti0.47)O3 ferroceramic is investigated in the electric fields of 0 < E < 6... 相似文献
9.
Physics of the Solid State - The effect of La concentration on the kinetic character of the induced phase transition in PbMg1/3Nb2/3O3–25PbTiO3 ferroceramics is studied. Below the... 相似文献
10.
The influence of different regimes of application of a dc electric field (0 < E < 4 kV/cm) on structural phase transformations and behavior of the phase boundary in [001]-oriented single crystals PMg1/3Nb2/3O3-xPbTiO3 (PMN-xPT) with compositions near the morphotropic phase boundary (x = 28 and 32%) and far from it (x = 13%) has been investigated. The studies have been performed using optical methods, namely, optical transmittance and small-angle
light scattering. It has been revealed that the number, symmetry, and stability of field-induced phases depend on the regime
of electric field application. During cooling of the PMN-28PT crystals from the cubic phase in the field (FC regime), the
tetragonal phase is induced already in weak fields of ∼0.5 kV/cm, whereas even a field of 3 kV/cm is insufficient for inducing
this phase by applying the field in the ferroelectric phase. In the PMN-32PT crystal (which has a composition closer to the
morphotropic phase boundary as compared to that of the PMN-28PT crystal) in the FC regime and when the field is applied in
the ferroelectric phase, the tetragonal phase is induced already in weak electric fields, even though this phase in the latter
case appears to be unstable. The E-T phase diagrams have been constructed for different regimes of field application. The possible factors responsible for the
observed differences have been discussed. 相似文献