Cubic Pyrochlore Bismuth Zinc Niobate Thin Films for High-Temperature Dielectric Energy Storage

Thin films of cubic pyrochlore bismuth zinc niobate, a lead-free dielectric, were fabricated using a solution chemistry based upon the Pechini method. Scanning electron microscopy confirmed that the films are smooth and mostly dense. The films exhibit a dielectric constant of 145 +/- 5, a low dielectric loss of 0.00065 +/- 0.0001, and a room temperature, 1kHz maximum field of approximately 4.7MV/cm. At frequencies of 100Hz and 10 kHz, the maximum field sustained by the material increased to 5.0MV/cm and 5.1MV/cm, although the dielectric loss increased to 0.0065 +/- 0.001. At a measurement frequency of 10kHz, the maximum energy storage density was similar to 60.8 +/- 2.0J/cm(3), while at a measurement frequency of 100Hz, the maximum energy storage was similar to 46.7 +/- 1.7J/cm(3). As the temperature was increased to 200 degrees C, the breakdown strength of the films decreased, while the loss tangent remained modest. At 200 degrees C and a measurement frequency of 100Hz, the maximum energy storage density was similar to 23.1 +/- 0.8J/cm(3), and at 10kHz, the maximum energy storage density was similar to 27.3 +/- 1.0J/cm(3).