Mn and/or rare earth-doped xCaTiO₃ - (1-x)CaMeO₃ dielectrics, where Me=Hf or Zr and x=0.7, 0.8, and 0.9 were developed to yield materials with room temperature relative permittivities of Εr ~ 150-170, thermal coefficients of capacitance (TCC) of ± 15.8% to ± 16.4% from -50 to 150°C, and band gaps of ~ 3.3-3.6 eV as determined by UV-Vis spectroscopy. Un-doped single layer capacitors exhibited room temperature energy densities as large as 9.0 J/cm₃, but showed a drastic decrease in energy density above 100°C. When doped with 0.5 mol% Mn, the temperature dependence of the breakdown strength was minimized, and energy densities similar to room temperature values (9.5 J/cm₃) were observed up to 200°C. At 300°C, energy densities as large as 6.5 J/cm₃ were measured. These observations suggest that with further reductions in grain size and dielectric layer thickness, the xCaTiO₃ - (1-x)CaMeO₃ system is a strong candidate for integration into future power electronics applications.To further improve the high temperature, high field reliability of these material systems, rare earth donor doping has been utilized. Initially, 1 mol% doping with Dy, Gd, and Sm showed the most significant reduction in high temperature, high field conductivity. Further investigation of Dy co-doping with 0.5 mol% Mn , Mg, and (Mn+Mg) showed the most significant increase in Ca(Ti₀.₈Hf₀.₂)O₃ resistivity from 4.61 MΩ.m with only Mn doping to 176 GΩ.cm with Dy and Mg co-doping. Material systems were characterized using capacitance and dielectric loss versus temperature, current-voltage (I-V), UV-Vis spectroscopy for band gap determination, and polarization versus field measurements.
High Temperature, High Energy Density Dielectrics for Power Electronics Applications
Sae Int. J. Mater. Manf
Sae International Journal of Materials and Manufacturing
SAE 2012 Power Systems Conference ; 2012
Sae International Journal of Materials and Manufacturing ; 6 , 1 ; 77-84
2012-10-22
8 pages
Conference paper
English
High Temperature, High Energy Density Dielectrics for Power Electronics Applications
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