Abstract: The invention provides apparatus and methods for heating and cooling ferroelectric materials during a conversion between thermal and electrical energy. One method comprises the use of a fluid that performs repeated heating and cooling cycles, e.g., ‘thermal cycling’, of ferroelectric materials during the evaporation and condensation of a phase changing fluid. The systems, devices, and methods eliminate the need for external inputs such electrical or mechanical power, thereby improving the overall efficiency of the energy conversion. One apparatus comprises liquid-retaining wicks that helps fluid distribution and expands the range of operational environment for the energy system. Ultimately, the uniformity and speed of various embodiments of the thermal cycler apparatus and method provide improvements in conversion efficiency and reductions in parasitic loss over current thermal cyclers.