摘要:

Experimental results of Roshelle salt group crystals dielectric spectra at ultra-low frequencies are discussed. In the vicinity of the phase transition point, the coexisting Cole-Cole type dispersion regions of dielectric permittivity are associated with the dynamics of defects of, both domain and non-domain nature. For the 180 plane domain structure model, the quantitative values of domain dynamics parametres in real crystals have been obtained.

ISSN:0731-5171    

DOI:10.1080/07315178808200674

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Dispersion of ε* dielectric complex permittivity of Roshelle Salt (RS) poly-domain crystals has been investigated in ultralow frequency range of weak sinusoidal electric field. Two Cole-Cole type ε* dispersion regions were found in RS polar phase. Effects of applied constant electric field and shering stress on the parametres of these ε* dispersion regions and their temperature dependences have been analysed. The values of electric field, shearing stress and activation energy of electric polarization relaxation for both dispersion regions have been determined.

ISSN:0731-5171    

DOI:10.1080/07315178808200675

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Influence of the damped optical phonons on the spin-lattice relaxation rate is considered. In the second order of the perturbation theory the temperature dependence of the transition probability is calculated in the vicinity of the phase transition temperature Tc. It is shown that Raman relaxation rate is the main contribution in the anomalous relaxation processes.

ISSN:0731-5171    

DOI:10.1080/07315178808200676

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The description of uniaxial cluster ferroelectrics in a wide temperature range, including a phase transition point, by means of the collective variables method is suggested. The peculiarities of critical behaviour of ferroelectrics cluster system with dipole-dipole interaction are investigated.

ISSN:0731-5171    

DOI:10.1080/07315178808200677

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Excitations in semi-infinite ferroelectrics of order-disorder type are analysed. The temperature dependence of relevant parameters is included by the use of the equivalent bosonic Hamiltonian of ferroelectrics. It turned that in the system appear standing waves (volume states) as well as the states, localized in the vicinity of boundary surface (surface states under specific relation connecting lattice deformation and ordering parameters.

ISSN:0731-5171    

DOI:10.1080/07315178808200678

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The temperature dependences of the dielectric properties, conductivity, spontaneous polarization as well as the effect of hydrostatic pressure on the anomalies of these properties have been investigated. The β-TlInS2crystals are shown to be often a mixture of the polytypes. Transition into a ferroelectric state for some of the β-TlInS2polytypes is not preceded by an incommensurats phase transition.

ISSN:0731-5171    

DOI:10.1080/07315178808200679

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

This short note reports some results concerning the study of pyroelectric effect in BCCD-(CH3)3NCH2COO.CaCl2.2H2O. The pyroelectric coefficient along the crystallographic b axis reveals anomalies at the transition points between the different commensurate and incommensurate phases existing in this material. The integration of the pyroelectric current shows the existence of small polarizations for the commensurate phase q=2/7 and below T=48K.

ISSN:0731-5171    

DOI:10.1080/07315178808200680

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Accurate measurements of gyration tensors g11(=-g22) and electrogyration effect of KH2PO4were made by applying the improved HAUP method. g11diverges conspicuously when the temperature approaches Tc from above and below it, the behaviour being analyzed as obeying the Curie-Weiss law with a Curie-Weiss constant of 7.35×10−4K. An electrogyration coefficient π13referring to the polarization manifests a characteristic nature of improper ferroelectrics.

ISSN:0731-5171    

DOI:10.1080/07315178808200681

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A free electron moving with velocity v≪c is enveloped in the electron positron lattice (epola) by an accompanying wave (AW), which has the de Broglie wavelength ΛB= h/mev, and also a channel diameter ΛB. There are 1043m−3allowed discrete values of ΛBand v in the epola. In solids, due to the strong interaction of the conduction electrons with the lattice, the conduction electrons have only one allowed state per atom, or 1029m−3. Hence, between two allowed states in the solid there are in average 1014allowed epola states. Interactions between certain AW's and the solid lattice may open some of these states to the conduction electrons. They then become free as in the epola and unrestricted by space charge as in the ionic matrix of metals. Conditions are discussed for the occurrence of such superconductive transitions in different classes of solids.

ISSN:0731-5171    

DOI:10.1080/07315178808200682

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor