Kinetic evolution in the incommensurate phase in K2ZnCl4

Abstract Time evolution of dielectric constants in the incommensurate phase of K2ZnCl4 was observed. The dielectric constants showed a long-term relaxation when the sample was held at a constant temperature. They did not relax exponentially but obeyed a stretched exponential exp{-(t/τ)β} with β=0.6 and τ=22 min. at 436 K. This evidence indicates that the slow relaxation phenomenon can not be explained by the DDW theory, but is attributable to the kinetic process of nucleation and annihilation of discommensurations or to DDW diffusion with a wide distribution of relaxation times. No clear fine discontinuous stepwise changes in e were found even at the slow scanning speed of 0.001 K/min.

[1]  Lu,et al.  Phase transitions in K2ZnCl4. , 1992, Physical review. B, Condensed matter.

[2]  Shore,et al.  Logarithmically slow domain growth in nonrandomly frustrated systems: Ising models with competing interactions. , 1992, Physical review. B, Condensed matter.

[3]  J. Fousek,et al.  Ageing and reactivation of domain wall oscillations in the ferroelectric lock-in phase of purified Rb2ZnCl4 , 1991 .

[4]  F. Dénoyer,et al.  Memory effect and relaxational dielectric behaviour in the incommensurate phase of ferroelectric thiourea , 1990 .

[5]  H. Sakata,et al.  Nucleation and Annihilation of Discommensurations in the First-Order Commensurate-Incommensurate Phase Transition in K2ZnCl4 , 1990 .

[6]  B. Strukov.  Global hysteresis in ferroelectrics with incommensurate phases , 1989 .

[7]  F. Dénoyer,et al.  Dielectric anomalies in the incommensurate phase of urea-doped thiourea , 1988 .

[8]  P. Bastie,et al.  Birefringence and γ‐ray study of the irreversible behaviour of the incommensurate phase of quartz , 1988 .

[9]  H. Mashiyama,et al.  Time Evolution of the Incommensurate Phase in K2ZnCl4 Observed by Dielectric Measurements and X-Ray Scatterings , 1987 .

[10]  J. Jamet,et al.  Modulated phases, memory effect and defect density waves in thiourea , 1986 .

[11]  R. Blinc,et al.  Incommensurate phases in dielectrics , 1986 .

[12]  T. Nattermann.  Dielectric tails in K2ZnCl4: No evidence for an intrinsic chaotic state , 1986 .

[13]  H. Cummins,et al.  Time dependence of the soliton density in K2ZnCl4: Dielectric evidence for pair annihilation in the intrinsic chaotic state , 1985 .

[14]  H. Orland,et al.  Stretched exponential relaxation in systems with random free energies , 1985 .

[15]  K. Ema,et al.  Dielectric Dispersion in K2ZnCl4 around the Incommensurate-Commensurate Phase Transition Point , 1984 .