High-frequency thermal-electrical cycles for pyroelectric energy conversion

Abstract

We report thermal to electrical energy conversion from a 150 nm thick BaTiO 3 film using pyroelectric cycles at 1 kHz. A microfabricated platform enables temperature and electric field control with temporal resolution near 1 ls. The rapid electric field changes as high as 11 Â 10 5 kV/cm-s, and temperature change rates as high as 6 Â 10 5 K/s allow exploration of pyroelectric cycles in a previously unexplored operating regime. We investigated the effect of phase difference between electric field and temperature cycles, and electric field and temperature change rates on the electrical energy generated from thermal-electrical cycles based on the pyroelectric Ericsson cycle. Complete thermodynamic cycles are possible up to the highest cycle rates tested here, and the energy density varies significantly with phase shifts between temperature and electric field waveforms. This work could facilitate the design and operation of pyroelectric cycles at high cycle rates, and aid in the design of new pyroelectric systems. V C 2014 AIP Publishing LLC.

Thin-film ferroelectric materials and their applications

“…120). This discovery could point towards new materials for applications such as infrared sensors, pyroelectric electron emitters and pyroelectric energy conversion systems [145][146][147] .…”

Thermodynamic cycle optimization for pyroelectric energy conversion in the thin film regime

“…For comparison, Bhatia et al measured 3 mJ/cm 3 conversion in a thin film pyroelectric from an electric field span of 15 kV/cm, or about 7% the energy conversion density of this work using 15% of the applied electric field. The authors in this study also tested a range of electric field ramping rates, which as in effect testing more Brayton‐like, or Ericsson‐like, conversion cycles . They found that there was no major difference in energy density, which was likely from unintended miss‐timing of their conversion cycles where, for example, heating and discharging occur simultaneously .…”

Pyroelectric Energy Conversion in Doped Hafnium Oxide (HfO2) Thin Films on Area‐Enhanced Substrates

“…To compare our experimental results to classic ferroelectric materials, we use the electrothermal coupling parameter found in the efficiency equation (Equation ) as a figure of merit, where only materials with demonstrated energy conversion and measured properties are considered. In Figure c, BTO, PZT, and PMN‐PT, harvestable energy densities per cycle are shown with respect to the electrothermal coupling parameter. For the area‐enhanced Si‐doped HfO 2 films examined in this work, we obtain a temperature‐normalized energy density of 0.15 μJ cm −2 K −1 and a coupling factor of 1.7 × 10 −3 .…”