Pyroelectric Energy Conversion Research Articles

Electronic cooling and energy harvesting using ferroelectric polymer composites

Thermal management emerges as a grand challenge of next-generation electronics. Efforts to develop compact, solid-state cooling devices have led to the exploration of the electrocaloric effect of ferroelectric polymers. Despite recent advances, the applications of electrocaloric polymers on electronics operating at elevated temperatures remain essentially unexplored. Here, we report that the ferroelectric polymer composite composed of highly-polarized barium strontium titanate nanofibers and electron-accepting [6,6] phenyl-C61-butyric acid methyl ester retains fast electrocaloric responses and stable cyclability at elevated temperatures. We demonstrate the effectiveness of electrocaloric cooling in a polymer composite for a pyroelectric energy harvesting device. The device utilizes a simulated central processing unit (CPU) as the heat source. Our results show that the device remains operational even when the CPU is overheated. Furthermore, we show that the composite functions simultaneously as a pyroelectric energy converter to harvest thermal energy from an overheated chip into electricity in the electrocaloric process. This work suggests a distinct approach for overheating protection and recycling waste heat of microelectronics.

Large pyroelectric energy conversion in lead scandium tantalate thin films

Non-linear pyroelectric energy harvesting using ferroelectric thin films exhibits high energy conversion, primarily due to their large breakdown field compared to bulks. Here, we report the pyroelectric energy conversion potential of lead scandium tantalate, Pb(Sc1/2Ta1/2)O3 (PST) thin film fabricated on a c-sapphire substrate using chemical solution deposition. To enable the application of high electric field and to assess the pyroelectric energy conversion performance, interdigitated electrodes were deposited on the PST thin film. A maximum harvested energy density of 9.1 J cm−3 per cycle was deduced from polarization measurements in films undergoing an Olsen cycle between 0 °C and 150 °C when the electric field was varied between 50 and 1500 kV/cm. Furthermore, PST thin films can reach up to 27 % of Carnot efficiency for a temperature interval of 10 K between 30 °C and 40 °C. This study highlights the significance of PST thin films for electro-thermal energy harvesting and promising opportunities for enhancing the conversion efficiency and power density using thin films or thin film multi-layer capacitors in the future for thermal energy harvesting.

Pyroelectric energy conversion efficiency of ferroelectrics in Olson cycle

Phenomenology theory of ferroelectrics is developed to solve pyroelectric energy conversion performances in Olson cycle by using rotation and coupling of dipoles depending on temperature and electric field. Numerical simulation shows electric field related pathway of cycle. The conversion efficiency of an Olson cycle has a peak at temperature over Curie temperature, which is higher for increased low temperature point. A horary conversion efficiency is developed to compare conversion efficiencies in different temperature range. The conclusion is that the horary efficiency is higher when the low temperature point is higher and the high temperature is lower.

Enhanced functional reversibility in lead-free ferroelectric material over long cycle pyroelectric energy conversion

Enhanced functional reversibility in lead-free ferroelectric material over long cycle pyroelectric energy conversion

Relaxor-antiferroelectric hybrids for pyroelectric energy conversion from low-grade heat using flexible PVDF-TrFE-CTFE-NaNbO3 nanocomposite films

Nowadays, researchers focus more on developing smart materials that respond to different stimuli for harvesting energy output. In this paper, the pyroelectric energy harvesting capabilities of smart terpolymer poly(vinylidene-fluoride-trifluoroethylene-chlorotrifluoroethylene) [PVDF-TrFE-CTFE]-based nanocomposites have been investigated. Sodium niobate (NaNbO3) from the perovskite family is selected as the filler. The Sol-gel method is used to synthesise NaNbO3 nanoparticles, and solvent-cast films for different weight fractions (0–20%) of fillers have been fabricated. Structural, morphological, and dielectric properties of the polymer nanocomposite samples were done at room temperature. The ferroelectric properties of the terpolymer is improved with filler addition. The thermal stability of composite films was confirmed using differential scanning calorimetric (DSC) studies. The thermodynamic Olsen cycle was applied to nanocomposites for calculating the harvested energy output. Maximum energy density is obtained for higher filler loading (20 wt % sodium niobate). The operating temperatures were selected at 303 K and 333 K with an applied field of 130 kV/cm. The results show that including NaNbO3 in the relaxor terpolymer matrix considerably enhances the energy harvesting density of the nanocomposites, indicating that they are promising materials for designing thermally stable energy harvesting systems.

Exploring Electro‐Thermal Interconversion in Oxide Superlattices Across Polarization Behavior Transition

AbstractDue to the great demand for global energy consumption, electro‐thermal energy interconversion has drawn great attention. Ferroelectrics as promising candidates realize energy conversion through pyroelectric and electrocaloric effects, but their efficiency is not sufficiently high. Herein, using phase‐field simulations, it is demonstrated that superlattices with polar topologies tend to have various polarization behaviors, and the antiferroelectric‐ to paraelectric‐like phase transition induces a large polarization change and thus a high pyroelectric response. In KNbO3/KTaO3 superlattices, the pyroelectric energy conversion has a scaled efficiency of 50% and the equivalent ZT of 7.2, and the electrocaloric cooling temperature reaches 40 K. The operation temperature can be tuned by changing the thickness of the superlattice. The results reveal that oxide superlattices are competitive in energy harvesting and conversion, thus creating new application prospects for polar topologies.

Synergetic H-Bonding and C-T Interaction-Mediated Self-Assembled Structure Results in a Room-Temperature Ferroelectric Material Exhibiting Electric Field-Induced Dipole Switching and Piezo- and Pyroelectric Energy Conversion

Synergetic H-Bonding and C-T Interaction-Mediated Self-Assembled Structure Results in a Room-Temperature Ferroelectric Material Exhibiting Electric Field-Induced Dipole Switching and Piezo- and Pyroelectric Energy Conversion

Studies on PVDF/ferrite composite films on flexible substrates for pyroelectric energy conversion

Multiferroic flexible composite films on ITO-coated PET substrates for pyroelectric energy conversion. A maximum figure of merit of 8.67% was observed in 5 wt% of MnFe2O4 and 12.19% in 10 wt% of NiFe2O4 composite film.

Peculiarities of the pyroelectric current generated using a LiNbO3 single crystal driven by low-frequency sinusoidal temperature variation

Lithium niobate (LiNbO3) single crystal is one of the pyroelectric materials, which can be applicable in energy storage and conversion devices. A theoretical and experimental study of the sinusoidal temperature variation of a single crystal of LiNbO3 with ultra-low frequency of 1–80 mHz is presented here. The previously unreported phenomenon of the optimal frequency range with the maximum amplitude of pyroelectric current oscillations is shown. It is noted that the observed effect is very sensitive to the thermal properties of the material. The impact of thermal properties of the crystal on the optimal frequency range is discussed. The accurate calculations of the pyroelectric coefficient using sinusoidal temperature variation are introduced. The observed phenomenon can be applied in pyroelectric energy converters and storage devices having a cycle time of 10–1000 s.

Fluorine-containing ferroelectric polymers: applications in engineering and biomedicine

Highly polar fluorine-containing ferroelectric polymers based on vinylidene fluoride refer to the class of electroactive polymers suitable for various engineering applications. Under usual crystallization conditions, polycrystalline texture is formed, while after high-voltage polarization, it is transformed into a non-centrosymmetric structure, which gives rise to high piezoelectric and pyroelectric responses. Such materials can be used for pyroelectric energy conversion. Owing to high impact strength, ferroelectric polymers can serve as materials for alternative energy sources that convert dynamic impact energy into electricity. The non-linearity of electric response (owing to ferroelectricity) and high breakdown fields offer opportunity of using them in capacitive charge storage devices. The intense dynamics of the amorphous phase provides a rapid discharge of the stored energy into an external circuit. In view of the considerable fraction of the amorphous phase ( 50%) in fluorine-containing ferroelectric polymers and high dielectric permittivity of the amorphous phase, it is possible to change the system entropy by applying an electric field. In the case of pulsed field, this provides a temperature drop; therefore, these materials (especially as composites) are promising for the design of solid-state refrigerators. The high thermoplasticity of these polymers is useful for the design of sensors <i>e.g.</i>, microphones) with a patterned active membrane surface and enhanced characteristics. Biocompatibility and low acoustic impedance (close to the impedance of biological tissues) accounts for the possibility of using these polymers as biosensors. When domains are present in a ferroelectric film, strong local electric fields appear, which can affect the activity of living cells. Using the direct and reverse piezoelectric effect, it is possible to stimulate and control the functions of various tissues, including the nervous tissue. <br> The bibliography includes 463 references.

Mechanism of energy conversion of ferroelectric in pyroelectric cycle

<p indent="0mm">“Waste heat” in the environment can be converted into electric energy by the Seebeck effect of semiconductor and pyroelectric effect of ferroelectrics ascribed to induction effect of polarization by electric field applied, energy conversion originates from the difference of polarization hysteresis electric field (<italic>P-E</italic>) loops between two different temperatures. Two isothermal processes and two iso-electric field processes form a pyroelectric cycle. By absorbing and releasing heat between two thermal reservoirs, a ferroelectric change its polarization successively so as to convert heat into electricity in a thermal-electric cycle, similar to the Carnot cycle. Output electric energy is the area enclosed by the cycle. For a constant high temperature environment, how to design a ferroelectric with proper Curie temperature and how to set cycling condition to match the temperatures to enlarge the area of a cycle are the two crucial problems. Experiment researches on pyroelectric energy conversion have been performed since the 1960s. The theoretic research was limited on simple expressions due to the difficulty on solving <italic>P-E</italic> loop. The <italic>P-E</italic> loop of ferroelectrics stems from rotation of dipoles and polarization hysteresis. In three-dimensional ferroelectrics, Gibbs free energies in the orientation directions of dipoles change with applied electric field differently, which causes changes in probabilities of dipole in different directions, i.e., rotation effect of dipoles. By introducing a coupling factor in the parallel dipoles the hysteresis effect was solved. The above solutions are extended to pyroelectric cycle to solve the problems referring to two isothermal processes and two iso-electric field processes with different initial condition. By combining the rotation effect and coupling effect that the coupling strength between dipoles is proportional to the rotated dipoles in the field direction during the field increasing process and persists to the same value in the field withdrawing process, mechanisms of polarization hysteresis are derived as several formulae. By editing a software program, numerical simulation method is used by setting values to the parameters to obtain evolution of polarization in the four processes of a cycle. Simulated result provides path of a cycle, depending on the maximal electric field (<italic>E</italic>_max). For a <italic>P-E</italic> loop in the first quadrant, there is a middle-curve rises from zero point to the top point of the loop, and an up-curve reduces from the top point to the remnant polarization at the zero field. In a cycle for a large enough <italic>E</italic>_max, the iso-low temperature process passes along the up-curve in the opposite direction, while for a smaller <italic>E</italic>_max, the process starts between the middle-curve and the up-curve and then transforms to the up-curve with the increase in the field because of impact of the small remnant polarization produced by <italic>E</italic>_max. The efficiency of pyroelectric cycling depends on cycling temperatures relative to Curie temperature and magnitude of the fields. High temperature is set above or below Curie temperature, and low temperature is set much below Curie temperature. Results show that when the low temperature is closer to Curie temperature, and high temperature is slightly higher than Curie temperature, pyroelectric energy conversion efficiency is higher and stable. When the high and low temperatures are close to the Curie temperature, the maximum pyroelectric conversion efficiency is obtained, but it decreases with the increase of the high temperature rapidly. A scaled efficiency, the efficiency relative to the Carnot cycle, decreases with the increase of temperature.

Phase transition enhanced pyroelectric nanogenerators for self-powered temperature sensors

Pyroelectric materials are of interest for waste heat utilization and thermal detection. However, the low output current and inefficiency reduces their effectiveness. Here, we utilize the abrupt decrease in polarization of ferroelectric BaTiO3 materials around Curie temperature to improve the output performance of a pyroelectric nanogenerator. The variation of the polarization leads to a large change in the density of surface free charges, resulting in an increase of pyroelectric current. We have designed a temperature control and recording system to realize direct measurement of the pyroelectric output current. The pyroelectric current, power and energy conversion efficiency of the device near the Curie temperature were measured to be 15.6-fold, 18-fold and 15.8-fold higher than those acquired near room temperature. Moreover, the temperature induced current and charge density enhancement can be applied to detect temperature and temperature change. The responsivity of the self-powered temperature sensor near Tc is 120 nC/cm2∙K, which 4.8 times higher than that near room temperature (25.1 nC/cm2∙K). The results confirmed the ability to exploit a ferroelectric phase transition for pyroelectric performance enhancement.

Wireless and Battery-Less Tamper Detection With Pyroelectric Energy Converter and High-Overtone Bulk Acoustic Resonator

This paper describes a proof-of-concept sensor (1) that can detect and record (without battery) a semiconductor-chip tamper activity (i.e., de-soldering followed by mechanical banging) which a counterfeiter does to scavenge semiconductor chips from a printed circuit board and (2) that can be wirelessly interrogated without need to open semiconductor packages. The sensor is based on a High-overtone-Bulk-Acoustic-Resonator (HBAR) working as a Radio-Frequency Identification (RFID) tag, which can be permanently broken down by the voltage and charge generated by a pyroelectric-energy-converter (PEC). The concept is demonstrated through connecting a 7.5 GHz HBAR (based on a 350 nm-thick ZnO thin film deposited on sapphire) to a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5\times 5\times0.15$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> lithium niobate-based PEC, via a Kapton-copper cantilever switch. When the switch is turned on (due to a mechanical shock emulating a counterfeiter’s mechanical banging), the accumulated charge on the PEC (produced by 250 °C temperature rise emulating a counterfeiter’s de-soldering) generates an electrical pulse with 9.6 V peak voltage and 1.36 nC charge transfer to an 8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{M}\Omega $ </tex-math></inline-formula> load (close to the HBAR’s resistance). The PEC’s voltage and charge are shown to permanently breakdown the ZnO film on the HBAR ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.1\times 0.1\times0.33$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) having a quality factor (Q) of about 2,500, so that the Q drops to near zero, drastically changing the RF absorption/scatter characteristics. A wireless interrogation is demonstrated by having a pair of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 2\times0.2$ </tex-math></inline-formula> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> microstrip patch antennas, one of which is connected to HBAR while the other one is connected to a network analyzer working as a wireless interrogator.

Multi-objective optimization of pyroelectric thermal–electrical cycles

Pyroelectric thermal–electrical cycles enable a class of solid-state heat engines that convert waste heat to electrical energy. This article numerically investigates thermal-to-electrical energy conversion in a PbZr0.52Ti0.48O3 (PZT) pyroelectric layer near room temperature and optimizes operating parameters to maximize the electrical energy output. A general thermodynamic cycle is modeled after the prototypical pyroelectric Ericsson cycle—implemented based on the Ginzburg–Landau–Devonshire theory—with variable operating temperature range, and heating/cooling and charging/discharging time intervals. We used a Pareto optimization approach to simultaneously maximize electrical energy density and power density for different PZT sample and cycle parameters. The evaluated Pareto optimal fronts showcase the possibility of achieving multiple optimal solutions and highlight the trade-off between output energy density and power density in pyroelectric energy conversion. Specifically, we demonstrate that a 4× enhancement in power density is achievable with a less than 10% reduction in energy density for the same sample and operating conditions primarily by optimizing heat transfer. The multi-objective optimization approach and results presented in this study could provide a framework to facilitate the design and operation of pyroelectric cycles for waste heat energy harvesting systems.

Pyroelectrics on purpose: A perspective on generation vs harvesting

Solid-state pyroelectric heat engines that utilize the temperature and electric field dependence of electric displacement are promising for high-efficiency high-power thermal-to-electrical energy conversion. However, one of the key challenges for pyroelectric energy conversion is the inaccessibility of tunable transient heat sources for energy harvesting. This Perspective analyzes the potential of thermal waveform engineering for pyroelectric energy generation. We use the Landau-Devonshire phenomenological model to evaluate the energy conversion performance of a representative pyroelectric material coupled to (1) static heat source/sink via thermal switches, and (2) modulated heat source. Using this thermodynamic analysis, which accounts for thermal and electrical losses, we demonstrate a path toward maximizing pyroelectric energy conversion performance through purposeful thermal and electrical control.

High Entropy Oxide Relaxor Ferroelectrics.

Relaxor ferroelectrics are important in technological applications due to strong electromechanical response, energy storage capacity, electrocaloric effect, and pyroelectric energy conversion properties. Current efforts to discover and design materials in this class generally rely on substitutional doping as slight changes to local compositional order can significantly affect the Curie temperature, morphotropic phase boundary, and electromechanical responses. In this work, we demonstrate that moving to the strong limit of compositional complexity in an ABO3 perovskite allows stabilization of relaxor responses that do not rely on a single narrow phase transition region. Entropy-assisted synthesis approaches are utilized to synthesize single-crystal Ba(Ti0.2Sn0.2Zr0.2Hf0.2Nb0.2)O3 [Ba(5B)O] films. The high levels of configurational disorder present in this system are found to influence dielectric relaxation, phase transitions, nanopolar domain formation, and Curie temperature. Temperature-dependent dielectric, Raman spectroscopy, and second-harmonic generation measurements reveal multiple phase transitions, a high Curie temperature of 570 K, and the relaxor ferroelectric nature of Ba(5B)O films. The first-principles theory calculations are used to predict possible combinations of cations to design relaxor ferroelectrics and quantify the relative feasibility of synthesizing these highly disordered single-phase perovskite systems. The ability to stabilize single-phase perovskites with various cations on the B-sites offers possibilities for designing high-performance relaxor ferroelectric materials for piezoelectric, pyroelectric, and electrocaloric applications.

Microstructural tuning: A route towards realization of enhanced pyroelectric figure of merits of Sr and Zr doped barium titanate ceramics

In this article, we emphasize microstructural tuning approach to realize an enhanced pyroelectric energy conversion associated figure of merits (FOMs) in ferroelectric Ba0.85Sr0.15Zr0.1Ti0.9O3 (BSZT) ceramics. To develop porous microstructure in the ceramics, we employ BURPS (burning out of polymer sphere) technique using PMMA as a pore-forming agent. In present scenario, the porosity in the ceramics is intentionally being introduced for the noble cause of enhancement in pyroelectric figure of merits (Fe*, Fe,Fv). Here, we investigate the effect of porosity on structural, morphological, dielectric and ferroic characteristics and its correlation with pyroelectric property. We note that, in comparison to dense ceramic, the porous ceramics with 6.9% porosity level shows remarkable enhancement of 29% in Fe*, 24% in Fe, 53% in Fv at 303 K. The microstructural engineering in pyroelectric/ferroelectric ceramics opens the effective route towards the realization of high piezoelectric and pyroelectric figure of merits. Ferroic ceramics with good figure of merit are highly anticipated for their decisive role in the area of green energy harvesting, energy storage and infrared detection.

Enhanced Pyroelectric Coefficient in Ferroelectric Lead Zirconium Titanate Thick Films for Thermal Energy Harvesting Applications

Due to increase in growth population and energy demand, energy harvesting technology has become a sensational topic of research community. Amongst all the available energy harvesting technologies (mechanical, magnetic, wind, hydrothermal), harvesting waste heat has gained a lot of interest because of its cost effectiveness and availability of significant thermal fluctuations in industrial processes as well as in nearby surroundings. Therefore, efforts have been made on harvesting thermal energy through pyroelectric devices. Such devices have huge range of applications in fire alarms, heat sensors, infrared detectors, thermal imaging, gas analysis and so on. In the present study, the pyroelectric Lead Zirconium Titanate (PZT) thick films grown using modified sol-gel approach have been used for pyroelectric energy conversion. The effect of annealing temperature (450 °C, 450 °C and 650 °C) on the growth of PZT films has been monitored by investigating their dielectric, ferroelectric and pyroelectric properties. An appreciable enhancement in saturation and remnant polarizations from 17μC cm−2 to 24μC cm−2 and 13μC cm−2 to 22 μC cm−2 has been obtained when annealed temperature is increased from 550 °C to 650 °C respectively. A visible change in dielectric constant is also observed from 207 to 325 from dielectric constant–frequency curves with very small change in dielectric losses from 0.06 to 0.10 with increase in the annealing temperature from 550 °C to 650 °C at 1 MHz. The pyro electric coefficient and figure of merit are found to increase from 25 × 10−3 Cm−2K−1 to 230 × 10−3 Cm−2K−1 (p) and from 2.2 m2C−1 to 20 m2C−1 for the optimized PZT thick film based pyroelectric device with increase in the external DC bias field from 0.5 V to 2.5 V. The enhanced results of pyroelectric coefficient and figure of merit achieved in the present work are good indication of electrical energy harvesting through pyroelectricity.

Broad Distribution of Local Polar States Generates Large Electrothermal Properties in Pb-Free Relaxor Ferroelectrics

Electrothermal energy conversion provides attractive solutions for global energy management, such as energy harvesting from waste heat using pyroelectric energy conversion (PEC) and efficient cooli...

Low hysteresis and enhanced figure-of-merit of pyroelectric energy conversion at compatible phase transformation

The pyroelectricity of polar materials provides great potential for electricity generation from waste heat. The pyroelectric effect of the material can be magnificently enhanced at a first-order phase transformation due to the abrupt jump in spontaneous polarization within a narrow temperature range. Here, we show that the performance of energy conversion by phase transformation is inversely resonant with the hysteresis of thermally driven structural transformations in a (Ba1−xSrx) (Hf0.02Ce0.005Ti0.975)O3 system, corresponding to a singular lattice distortion mode satisfying the crystallographic compatibility condition. Among the finely tuned Sr compositions from 0.04 to 0.10, we discovered that Sr0.07 composition is a promising material candidate in this material system for pyroelectric energy conversion. Our work suggests a rational strategy of material development for pyroelectric energy conversion applications.