Effect of negative capacitances on high-temperature dielectric measurements at relatively low frequency

Barium ferrite (BaFe12O19) was elaborated and investigated in this work in terms of its capacitance-temperature characteristics. The curve taken at the fixed frequency of 1 kHz shows anomalous negative values of capacitance over the high-temperature regime. A complete analysis of this effect is carried out by performing as measurements at various temperatures. The results indicate that a resonance phenomenon, arising from the external electrical circuit and shifting from the higher frequencies to the lower ones with increasing temperature, is responsible for this unusual effect. (C) 1997 American Institute of Physics. [S0003-6951(97)03351-2].