Dezhi Su

Effect of Nd3+ substitution for Bi3+ on the dielectric properties and conduction behavior of Aurivillius NdBi4Ti3FeO15 ceramics

NdBi4Ti3FeO15 and Bi5Ti3FeO15 ceramics were prepared by solid state reaction. The effect of Nd3+ on dielectric and electrical properties was investigated in a wide range of frequencies and temperatures by dielectric/impedance spectroscopies. The combination of impedance and electric modulus analysis enabled the distinguishing of two relaxation behaviors that were assigned to originate from grains and grain boundaries. Kinetic analysis of temperature-dependent dielectric data was performed to probe the defect-related conduction. The results demonstrated that the Nd3+ substitution for Bi3+ significantly suppressed the conductivity and the ferroelectric transition temperature was decreased to ∼250 °C in NdBi4Ti3FeO15.

The effect of the phase structure on physicochemical properties of TMO materials: a case of spinel to bunsenite

It is worthwhile to comprehensively investigate the relationship between different phase structures and physicochemical properties of TMO materials. For investigating the phase structure effect, spinel Co3O4, NiCo2O4, and bunsenite NiO microflowers were rationally synthesized through a facile solvothermal method combined with a post-annealing process. The phase structures of final products were controlled by adjusting the Ni/Co addition ratio. The SEM and TEM results revealed that these Ni/Co oxides exhibited similar flower-like morphology; this provided convenience for investigation of their physicochemical properties in view of their phase structure. Compared with Co3O4 that exhibited superparamagnetic behavior, NiCo2O4 exhibited ferromagnetic characteristics because of the incorporation of nickel into the spinel structure. Co3O4 and NiCo2O4 demonstrated thermal catalytic ability higher than that of bunsenite NiO due to the more efficient electron transfer ability of the spinel structure. In view of the phase structures, this study provided a prospective case of research on the physicochemical properties of transition-metal oxide (TMO) materials.