CALCIUM-DOPING EFFECT ON TEMPERATURE COEFFICIENTS OF DIELECTRIC-CONSTANTS IN SRTIO3 CAPACITORS

SrTiO3 ceramic capacitors were studied to improve the temperature coef ficient, tau, of dielectric constants without decreasing the dielectri c constants. It was indicated that an addition of calcium in an insula ting reagent improved tau. From scanning electron microscopy and energ y-dispersive X-ray analysis measurements, the origin of this improveme nt was ascribed to the following layers: (1) the oxide layers which we re formed at the grain boundaries, and (2) the bismuth-oxide layers wh ich were formed on the sample surface.