Use of low-frequency sinusoidal temperature waves to separate pyroelectric currents from nonpyroelectric currents. Part I. Theory

This is the first of two papers wherein a new method is described which allows the analysis and evaluation of electric currents, such as pyroelectric currents and thermally simulated conductivity or currents arising from heated dielectric materials. It is shown for certain temperature and frequency ranges that the ac current from a nonpyroelectric material is in phase with a small sinusoidal temperature wave superimposed on a constant heating rate used to warm the samples. In addition, the ac current of pyroelectric origin is shown to be π/2 radians out of phase with the same temperature wave. Possible sources of error, such as undesired phase shifts resulting from slowly varying background currents or harmonics in the sinusoidal temperature wave, are also discussed.