Relaxorlike dielectric behavior in Ba0.7Sr0.3TiO3 thin films

Abstract

We present the results of a systematic dielectric study for sputter deposited barium strontium titanate thin film planar capacitors measured over a wide temperature range of 20–575K for frequencies between 1kHz and 1MHz. Our observations of dielectric loss peaks in the temperature and frequency domains cannot be understood in the typical framework of intrinsic phonon losses. We find that the accepted phenomenological Curie–von Schweidler dielectric behavior (universal relaxation law) in our barium strontium titanate films is only applicable over a narrow temperature range. An excellent fit to the Vogel-Fulcher expression suggests relaxorlike behavior in these films. The activation energy of the observed phenomenon suggests that oxygen ion motion play a role in the apparent relaxor behavior, although further experimental work is required to test this hypothesis.