Pyroelectric energy conversion using PLZT ceramics and the ferroelectric–ergodic relaxor phase transition

Abstract

This paper is concerned with direct conversion of waste heat into electricity by executing the Olsen cycle on lead lanthanum zirconate titanate (PLZT) ceramics undergoing a relaxor-ferroelectric phase transition. The Olsen cycle consists of two isothermal and two isoelectric field processes. First, the temperature-dependent dielectric properties were measured for x/65/35 PLZT. The polarization transition temperature of x/65/35 PLZT was found to decrease from 240 to 10 • C as x increased from 5 to 10 mol%. This suggests that the different compositions should be operated over different temperature ranges for maximum thermal to electrical energy conversion. The energy and power densities generated by the Olsen cycle using x/65/35 PLZT samples were measured by successively dipping the samples in isothermal dielectric oil baths. Large energy and power densities were obtained when the samples underwent the ergodic relaxor-ferroelectric phase transition. A maximum energy density of 1014 J l −1 per cycle was obtained with a 190 µm thick 7/65/35 PLZT sample cycled at 0.026 Hz between 30 and 200 • C and between 0.2 and 7.0 MV m −1 . To the best of our knowledge, this is the largest pyroelectric energy density ever demonstrated experimentally with ceramics, single crystals, or polymers. A maximum power density of 48 W l −1 was achieved using a 200 µm thick 6/65/35 PLZT sample for temperatures between 40 and 210 • C and electric fields between 0 and 8.5 MV m −1 at a frequency of 0.060 Hz. The maximum applied electric field and temperature swings of these materials were physically limited by dielectric breakdown and thermomechanical stress.

Novel Electrothermodynamic Power Generation

“…The produced loop area is considered as an energy density ( N D , the area of the D -E loop); the power density ( P D , = N D f ) is also evaluated from the area. [7][8][9][10][11][12][13][14] To the best of our knowledge, there is no application that satisfi es a true energy breakeven because of the diffi culties associated with fi nding a suitable energy source that can simultaneously give alternative heat and an electric fi eld. [7][8][9][10][11][12][13][14] In this study, a novel electrothermodynamic cycle is presented based on temporal temperature variation to obtain practical net energy from exhaust heat of automobile.…”

“…[ 8,9 ] To date, considerable effort, in terms of theoretical investigations, materials, and systems, has been devoted to developing the pyroelectric effect as a useful renewable energy source. [10][11][12][13][14] This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifi cations or adaptations are made. The copyright line for this article was changed on 14 May 2015 after original online publication.…”

Relationship Between the Material Properties and Pyroelectric‐Generating Performance of PZTs

“…[9][10][11][12] To date, considerable effort has been devoted to investigating the pyroelectric effect to develop a useful renewable energy source based on theoretical investigations, materials, and systems. [13][14][15][16][17][18] In the 1980s, Olsen et al reported on an electrothermodynamic cycle (Olsen cycle) using the pyroelectric effect and an external electric field, [19,20] which can be described by a loop of electric displacement, D, versus the electric field, E (D-E loop). The area denotes an energy density (N D , theoretical generating potential), and a power density (P D , = N D f ) can also be evaluated.…”

“…[13][14][15][16][17][18][19][20] However, despite these trials, this cycle has not yet been established in reality due to the difficulty of obtaining alternating high and low isothermal temperature periods. [13][14][15][16][17][18][19][20] In a previous study, we presented a novel electro-thermodynamic cycle based on a temporal temperature variation to obtain a practical net energy from the exhaust gas of an automobile. [1] The most representative pyroelectric and piezoelectric material, Pb(Zr x , Ti 1−x )O 3 (PZT, Fuji ceramics), was used.…”

Alternative Caloric Energy Conversions

“…However, other properties should be taken into account when choosing the appropriate pyroelectric material, such as a high electrical resistivity (to minimize the leakage current through the pyroelectric element), a low heat capacity (to minimize the heat input needed to change the temperature of the pyroelectric material) and a small hysteresis [59,60]. Furthermore, for some applications, the high dielectric strength of the pyroelectric material is important [61,62].…”