Crystallization mechanism and ac conductivity studies on strontium barium niobate glass–ceramics

The strontium barium niobate (SBN) glasses were synthesized through a melt–quenching method. Crystallization mechanism for SBN glass–ceramics has been investigated by differential scanning calorimeter and optical microscope. The value of activation energy for the crystallization process indicates a controlling step of Si–O band breaking while optical microscope analysis shows a surface crystallization phenomenon. The effect of crystallization time on ac conductivities for glass and crystal phase was carried out by impedance analysis. The value of conductivity exhibits a rising trend as the crystallization time is increased. The results showed a better temperature–sensitive behavior for the crystal phase. In the conductivity spectra, Jonscherʹs universal power law and double power law were separately used to the glass and the crystal phase polarization effect. Results of dc conductivity versus measuring temperature from both effects well obey the Arrhenius law. Moreover, the value of the activation energy indicates an oxygen vacancy conductivity mechanism for the SBN glass–ceramics.