Dielectric Spectroscopy of Calcium Titanate Processed by Spark Plasma Sintering

Area of Science:

• Materials Science
• Solid State Physics
• Ceramics Engineering

Background:

• Calcium titanate (CaTiO3) is a perovskite material with potential dielectric applications.
• Spark plasma sintering (SPS) offers rapid densification of ceramic powders.
• Understanding SPS parameter effects on CaTiO3 is crucial for optimizing its dielectric performance.

Purpose of the Study:

• To investigate the influence of SPS temperature on the phase stability and dielectric properties of CaTiO3.
• To determine optimal SPS processing parameters for producing stable dielectric ceramics.
• To correlate optical properties with dielectric behavior.

Main Methods:

• Compaction of CaTiO3 powder using spark plasma sintering (SPS) across a temperature range of 1100 °C to 1250 °C.
• Post-sintering annealing to address oxygen deficiency.
• Dielectric characterization (relative permittivity, loss tangent, DC resistivity) at 1 MHz.
• Optical reflectance measurements for band gap estimation.

Main Results:

• SPS temperature significantly affected density, porosity, and dielectric properties of CaTiO3.
• Annealing did not obscure the impact of SPS parameters on dielectric performance.
• Optical band gap estimations supported the dielectric results.
• No subtle lattice changes, observed in conventionally sintered samples, were confirmed in SPS-prepared CaTiO3.
• The best sample exhibited a relative permittivity of 370, a loss tangent of 0.008, and a DC resistivity of 3 × 10^12 Ωm.

Conclusions:

• SPS is a viable method for producing stable CaTiO3 dielectric ceramics.
• Specific SPS parameters can be tailored to achieve desired dielectric properties.
• The study provides valuable insights into processing-structure-property relationships in CaTiO3.