Pinyang Fang

Dc-bias-field-induced Dielectric Relaxation and AC Conduction in CaCu3Ti4O12 Ceramics

The dielectric relaxation and ac conduction of CaCu3Ti4O12 (CCTO) ceramics were investigated at different temperatures under a dc bias. The dc bias gives rise to space charge accumulation, i.e. an electrode response, resulting in the significant increase of dielectric permittivity and dielectric loss tangent. Two Debye-like relaxations, arising from electrode and grain boundary responses, are present at low frequency with an increase of the dc bias. The electrode and grain boundary relaxations are distinguished according to the impedance spectroscopy and the frequency-dependent ac conductivity. The relaxation times of electrode and grain boundary relaxation are 0.955 ms and 0.026 ms, respectively, with a dc bias of 10 V at 328 K.

Lanthanum induced larger polarization and dielectric relaxation in Aurivillius phase SrBi2−xLaxNb2O9 ferroelectric ceramics

Ferroelectric ceramics SrBi2−xLaxNb2O9 (SBLNO) were prepared by a solid state reaction process. X-ray diffraction analysis indicated that single phase layered perovskites were obtained. The maximum dielectric permittivity peak broadened gradually with the lanthanum content increasing indicated that the phase transition from normal ferroelectrics to relaxorlike ferroelectrics occurs in SBLNO. The modified Curie–Weiss (CW) law was used to describe the relaxor behavior of SBLNO ceramics. The relaxation indication coefficient (γ) was estimated from a quadratic fit of modified CW law and was found to be 1.71 and 1.72 for SBLN20 and SBLN30 specimens, respectively. The substitution of La3+ ions for Bi3+ ions in the Bi2O2 layers resulted in a shift in the Curie point to lower temperature and an increase in remanent polarization and electrical field-induced strain. The maximum strain for SBLN30 specimen was found to be about 2.5×10−5 at the 5 MV/m. The nature of relaxor behavior of SBLNO is attributed to the catio...

Erratum to: Structural and electrical properties of Ho3+-modified Pb(Zn1/3Nb2/3)O3–9PbTiO3 single crystals

The original version of the article contains errors about the temperature dependence of permittivity of PZN-9PT single crystals. The correct results are showed as follows: TR–T and TC of PZN–9PT single crystals were 363 and 447 K, respectively. The diffuse factor dA of PZN–9PT was 26.03 K (Table 2; Figs. 4, 5). According to the correct temperature dependence of dielectric permittivity of the PZN–9PT single crystals, the changed sentences of the abstract and conclusion are as follows: Revised Abstract: Ho-modified Pb(Zn1/3Nb2/3)O3– 9PbTiO3 (PZN–9PT) single crystals were grown through a flux method. Phase structure and microstructural morphology of the as-grown single crystals were performed by X-ray diffraction analysis and scanning electron microscopy. The refinement of the lattice parameters were obtained by the Rietveld method. The electrical properties of PZN–9PT single crystals were improved significantly by the modification of Ho ions. The rhombohedral–tetragonal phase transition temperature, coercive field at 15 kV cm, and remnant polarization of Ho-modified PZN-9PT single crystals were increased by 12 K, 2.4 kV cm, and 7.5 lC cm, respectively (i.e., 375.45 K, 5.9 kV cm, and 38.40 lC cm, respectively). Furthermore, Lorentz-type law was used to describe the dielectric relaxor behavior of the as-grown single crystals. Revised Conclusion: Ho-modified PZN–9PT single crystals were successfully grown by using the flux method. The as-grown single crystals had single perovskite structure. The enhancement of diffused phase transition and frequency dispersion was observed in the Ho-modified PZN–9PT single crystals. The diffuse factor dA ranged