Origin of Pyroelectricity in LiNbO3

We use molecular dynamics with a first-principles based shell model potential to study pyroelec- tricity in lithium niobate. We find that the primary pyroelectric effect is dominant, and pyroelec- tricity can be understood simply from the anharmonic change in crystal structure with temperature and the Born effective charges on the ions. This opens a new experimental route to studying py- roelectricity, 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, which could be used to optimize materials pyroelectricity, and the converse electrocaloric effect, peak as Tc is approached.