Modeling of dielectric behavior using modified Lorentz equation for Ca_0.1Sr_0.9R_0.1Bi_1.9Ta₂O₉ (R=Nd, Pr & La) ceramics

ABSTRACT

Ceramic samples Ca_0.1Sr_0.9R_0.1Bi_1.9Ta₂O₉ (R=Nd, Pr & La) were prepared by solid state double sintering route. XRD data confirms single phase formation with orthorhombic structure at room temperature. SEM studies revealed polycrystalline nature with randomly oriented needle and plate like morphology for Nd and La doped CSBT ceramics. Dielectric studies were carried out as a function of temperature at different frequencies. Modified Lorentz equation which gives information about the thermally activated orientation of dipoles was used to describe the temperature dependence of dielectric data. The activation energy for thermally activated orientation of dipoles for the present ceramic samples was found to be in the range 60–130 μeV depending up on the type of rare earth ion substitution in CSBT.

KEYWORDS:

• Ca_0.1Sr_0.9R_0.1Bi_1.9Ta₂O₉
• rare earth doping
• dielectric
• modified Lorentz equation

Funding

The authors thank Defence Research and Development Organization, New Delhi for the financial assistance.