Distinctive contributions to dielectric response of relaxor ferroelectric lead scandium niobate ceramic system

摘要

Dielectric properties of Pb(Sc1/2Nb1/2)O3 (PSN) ceramic system, prepared from mechanochemically activated powder, were studied in a broad temperature range of 150-750K. Various distinctive contributions were recognized in the detected reponse. A typical relaxor dispersive maximum, accompanied by a sharp dielectric anomaly showing a hysteretic behavior, reveals that developed disordered PSN ceramics undergoes a spontaneous relaxor-to-ferroelectric phase transition, even in zero electric field. At high temperatures, a strong dielectric dispersion due to the Maxwell-Wagner-type contributions of interface layers between the sample and contacts governs the detected response above 500K. The intrinsic high-temperature dielectric response follows, however, the universal scaling rather than the classical mean-field behavior. The latter can be rejected on the confidence level better than 99% according to the F-test and, furthermore, the analysis revealed a critical exponent that indicates a critical behavior associated with universality classes typically found in spin glasses. Finally, nearly perfect agreement between the fitting parameter of Tc=372±3K (obtained by analysis in the interval of 600-775K) and the experimentally detected value of this relaxor-to-ferroelectric phase transition temperature manifests that the low-temperature fingerprint behavior can be observed at much higher temperatures, well above the dispersive relaxor dielectric maximum.