Multifunctional Chiral Three-Dimensional Phosphite Frameworks Showing Dielectric Anomaly and High Proton Conductivity

Chair 3D Co(II) phosphite frameworks have been prepared by the ionothermal method. It belongs to chiral space group P3221, and the whole framework can be topologically represented as a chiral 4-connected qtz net. It shows a multistep dielectric response arising from the reorientation of Me2-DABCO in the chiral cavities. It can also serve as a pron conductor with high conductivity, 1.71 × 10−3 S cm−1, at room temperature, which is attributed to the formation of denser hydrogen-bonding networks providing efficient proton-transfer pathways.

Thermo- and light-triggered reversible interconversion of dysprosium–anthracene complexes and their responsive optical, magnetic and dielectric properties

[DyIII(SCN)3(depma)2(4-hpy)2] (1) shows reversible thermo-induced phase transition associated with thermochromism and dielectric anomaly and photo-induced dimerization with synergistic switching of luminescence, magnetic and dielectric properties.

Dielectric switching, SHG response and Pd(ii) adsorption of a multifunctional phase-transition complex

One-dimensional coordination polymer [(C2H4OH)C4H9NS]CdCl3 has the performance of dielectric switching and SHG response. And the compound can adsorb precious Pd(ii) and the adsorption could be monitored by dielectric anomaly and SHG signal.

Dipole defect decay and dielectric relaxation in Na0.5Bi0.5TiO3 single crystal

Electrical properties of heat treated in air and in vacuum Na0.5Bi0.5TiO3 single crystals were measured in AC field (f=1 kHz) in the range 300–800 K. Relaxation anomaly of permittivity ε(T) is observed near 700 K for the crystal heat treated in vacuum. It is argued that processing in vacuum generates the defect dipoles, which give rise to the dielectric anomaly. The character of the ε(T) experimental dependence is quite different from the predictions of Debye model. The non-Debye behavior of ε(T) is explained by the concentration decrease of dipole defects due to their thermal destruction at high temperatures. In addition, the ε(T) anomaly could be described more precisely by taking into consideration configurational and vibrational entropy of the subsystem of dipole defects. The observed dielectric relaxation is presumably attributed to reorientations of the dipole moments of Ti3+–VO centers.

Nature of polar state in 0.67BiFeO3–0.33BaTiO3

This study was conducted to further understand the nature of the polar state in 0.67BiFeO3–0.33BaTiO3 (0.67BF–0.33BT). A typical relaxor-type dielectric anomaly was observed (Tf = ~627 K, TB = ~820 K). The remnant polarization (Pr), maximum value of electrostrain (Sm) and magnitude strain at Ec in the bipolar mode (Sneg) increase clearly during heating (Pr, ~40 mC/cm2; Sm, 0.191 % under 40 kV/cm at 453 K). The first-cycle bipolar electrostrain loops indicate that the minimum strain on the negative side of the bipolar strain curves is negative. The slopes of the relative permittivity versus log frequency plots in unpoled (–21) and poled (–23) specimens are similar. The transition between the ergodic relaxor state and ferroelectric-like state does not involve a clear dielectric anomaly even in the poled specimen. Analyses based on the Rietveld refinement of XRD patterns, bright-field images and selected-area electron diffractions (SAED) demonstrate that the formation of the long-range ferroelectric domains is difficult under the poling field.

Tin based organic–inorganic hybrid semiconductors with reversible phase transition and dielectric anomaly

Two discrete tin based organic–inorganic hybrid compounds [(FMBA)2SnX6] (X = Cl and Br) showed reversible phase transition and dielectric anomaly above 400 K which were originated from the order-disorder of a fluorine-substituted organic amine.