Abstract
The dielectric spectroscopy of lead magnesium niobate relaxor ferroelectrics has been investigated over the frequency range of 102 to 107 Hz. The imaginary component was found to become nearly frequency independent below a freezing temperature, and scaled to a phenomenological equation involving the Vogel-Fulcher relationship. The absorption and Cole-Cole plots were found to become very broad near this freezing temperature. The relaxation time distribution was subsequently calculated by analogy to spin and dipolar glasses. A strong broadening of the distribution was found in the vicinity of the freezing temperature. It is proposed that this deviation from Debye behaviour is a result of the development of correlations between polar moments leading to the onset of nonergodicity near freezing.