Origin of pyroelectricity in LiNbO3

We use molecular dynamics with a first-principles-based shell model potential to study pyroelectricity in lithium niobate. We find that the primary pyroelectric effect is dominant, and pyroelectricity can be understood simply from the anharmonic change in crystal structure with temperature and the Born effective charges on the ions. This opens an experimental route to study pyroelectricity, as candidate pyroelectric materials can be studied with x-ray diffraction as a function of temperature in conjunction with theoretical effective charges. We also predict an appreciable pressure effect on pyroelectricity, so that chemical pressure, i.e., doping, could enhance the pyroelectric and electrocaloric effects.