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Although photothermal therapy is widely employed for tumor treatment because of its high tumor cell selectivity and low apoptosis resistance, heat-shock proteins (HSPs) impart resistance to heat-induced apoptosis in tumor cells, thus diminishing the therapeutic effectiveness. To this end, tin selenide (SnSe) was grown in situ on reduced graphene oxide (rGO) nanosheets to construct a photothermal–thermoelectric SnSe/rGO nanosystem. The rGO component converted near-infrared light energy into localized thermal energy, resulting in the thermal ablation of tumor cells. Meanwhile, SnSe converted temperature fluctuations into pyroelectric charges, which interacted with surrounding O2 molecules to generate reactive oxygen species that oxidized the amino acids on the HSPs, which changed the protein conformation and functionally damaged the tumor cells. In addition, rGO functioned as an efficient electron acceptor to increase electron mobility, thus enhancing the thermoelectric conversion efficiency of SnSe. Then, the SnSe/rGO nanosystem was incorporated into a poly-l-lactic acid bone scaffold to prevent tumor recurrence. Results showed that the composite scaffold not only exhibited good photothermal and thermoelectric effects. In vitro cell tests demonstrated that the scaffold generated 1O2 based on temperature fluctuations and the antitumor rate reached 86.6% against osteosarcoma MG-63 cells. [ABSTRACT FROM AUTHOR]

The strong pyrocatalytic dye decomposition of the BaTiO3/Pr2O3 heterojunction catalyst under cold–hot alternation conditions has been demonstrated in this work. For pure BaTiO3 nanofibers, ~54% rhodamine B (RhB) dye is decomposed under the cold–hot alternation of 29–57 ℃. With the loading content of Pr2O3 increases from 0 to 4 wt%, the pyrocatalytic decomposition ratio of RhB solution increases first and then decreases, eventually achieving a maximum of 91% at 3 wt%. The enhanced pyrocatalytic performance after loading Pr2O3 can be attributed to an internal electric field of the heterojunction, which effectively separates positive and negative charges. The strongly pyrocatalytic performance of BaTiO3/Pr2O3 makes it hopeful for applications in the dye wastewater treatment through harvesting the environmental cold–hot temperature alternation thermal energy in future.

Pyroelectric materials are naturally electrically polarized and exhibits a built-in spontaneous polarization in their unit cell structure even in the absence of any externally applied electric field. These materials are regarded as one of the ideal detector elements for infrared applications because they have a fast response time and uniform sensitivity at room temperature across all wavelengths. Crystals of the perovskite lead titanate (PbTi O 3 ) family show pyroelectric characteristics and undergo structural phase transitions. They have a high Curie temperature (the temperature at which the material changes from the ferroelectric (polar) to the paraelectric (nonpolar) phase), high pyroelectric coefficient, high spontaneous polarization, low dielectric constant, and constitute important component materials not only useful for infrared detection, but also with vast applications in electronic, optic, and MEMS devices. However, the preparation of large perfect and pure single crystals PbTi O 3 is challenging. Additionally, difficulties arise in the application of such bulk crystals in terms of connection to processing circuits, large size, and high voltages required for their operation. In this part of the review paper, we explain the electrical behavior and characterization techniques commonly utilized to unravel the pyroelectric properties of lead titanate and its derivatives. Further, it explains how the material preparation techniques affect the electrical characteristics of resulting thin films. It also provides an in-depth discussion of the measurement of pyroelectric coefficients using different techniques. [ABSTRACT FROM AUTHOR]

Pyroelectric materials, are those materials with the property that in the absence of any externally applied electric field, develop a built-in spontaneous polarization in their unit cell structure. They are regarded as ideal detector elements for infrared applications because they can provide fast response time and uniform sensitivity at room temperature over all wavelengths. Crystals of the perovskite Lead Titanate (PbTi O 3 ) family show pyroelectric characteristics and undergo structural phase transitions. They have a high Curie temperature (the temperature at which the material changes from the ferroelectric (polar) to the paraelectric (nonpolar) phase), high pyroelectric coefficient, high spontaneous polarization, low dielectric constant, and constitute important component materials not only useful for infrared detection, but also with vast applications in electronic, optic, and Micro-electromechanical systems (MEMS) devices. However, the preparation of large perfect, and pure single crystals of PbTi O 3 is challenging. Additionally, difficulties arise in the application of such bulk crystals in terms of connection to processing circuits, large size, and high voltages required for their operation. A number of thin film fabrication techniques have been proposed to overcome these inadequacies, among which, magnetron sputtering has demonstrated many potentials. By addressing these aspects, the review article aims to contribute to the understanding of the challenges in the field of pyroelectric materials, highlight potential solutions, and showcase the advancements and potentials of pyroelectric perovskite series including PbZrTiO3 (PZT), P b x C a 1 − x (PZN-PT), etc. for which PbTi O 3 is the end member. The review is presented in two parts. Part 1 focuses on material aspects, including preparation methods using magnetron sputtering and material characterization. We take a tutorial approach to discuss the progress made in epitaxial growth of lead titanate-based ceramics prepared by magnetron sputtering and examine how processing conditions may affect the crystalline quality of the growing film by linking to the properties of the substrate/buffer layer, growth substrate temperature, and the oxygen partial pressure in the gas mixture. Careful control and optimization of these parameters are crucial for achieving high-quality thin films with desired structural and morphological characteristics. [ABSTRACT FROM AUTHOR]

Pyroelectric materials are naturally electrically polarized and exhibits a built-in spontaneous polarization in their unit cell structure even in the absence of any externally applied electric field. These materials are regarded as one of the ideal detector elements for infrared applications because they have a fast response time and uniform sensitivity at room temperature across all wavelengths. Crystals of the perovskite lead titanate (PbTiO3) family show pyroelectric characteristics and undergo structural phase transitions. They have a high Curie temperature (the temperature at which the material changes from the ferroelectric (polar) to the paraelectric (nonpolar) phase), high pyroelectric coefficient, high spontaneous polarization, low dielectric constant, and constitute important component materials not only useful for infrared detection, but also with vast applications in electronic, optic, and MEMS devices. However, the preparation of large perfect and pure single crystals PbTiO3 is challenging. Additionally, difficulties arise in the application of such bulk crystals in terms of connection to processing circuits, large size, and high voltages required for their operation. In this part of the review paper, we explain the electrical behavior and characterization techniques commonly utilized to unravel the pyroelectric properties of lead titanate and its derivatives. Further, it explains how the material preparation techniques affect the electrical characteristics of resulting thin films. It also provides an in-depth discussion of the measurement of pyroelectric coefficients using different techniques.

Harvesting all-present environmental waste heat of decentralized, disordered, and diffused forms promises energy sustainability and carbon neutrality to meet the UN’s climate target [1]. The non-static waste heat or temporal temperature change (dT/dt), which is of equal importance as the spatial temperature gradient (dT/dx) [2], though commonly existed in the surroundings (e.g., human respiration, water vapours, and exhaust pipes; Fig. 1 and Table S1) according to the second law of thermodynamics, is still far from practice due to inefficiency, intricacy, and instability in powering consumer electronics [3,4]. Providentially, the pyroelectric effect allows for scavenging temporal temperature variations via spontaneous polarization change, making it an attractive approach for direct heat-to-electricity conversion from non-static thermal sources. Pyroelectricity is typically determined by p = ∂P/∂T (P = PS + PE, PE = εE) [5,6], where p is the pyroelectric coefficient, PS and PE are spontaneous and electric polarizations with respect to the applied thermal field and electric field (E), respectively, and ε is the dielectric constant. While tremendous efforts have been made to improve the p of polar materials (up to ∼ 10 mC m−2 °C−1) [7] and the power density of heat harvesters (up to ∼ 10 mW m−2) [8–10] over the past 50 years (Table S2), their large intrinsic impedance (in the level of MΩ) and low energy conversion efficiency (0.1‰) [11] have hindered the potential implications in the sustainable power supply of ever-increasing IoT-based electronics demands. In this short review, we first discuss the fundamental of electric polarization manipulation of typical polar materials for boosting p. Then, the state-of-the-art p versus Curie temperature (TCurie) of various pyroelectric materials is benchmarked. Next, paradigm-changing progress in tailoring the material properties and device configurations, as well as external electric/thermal field modulations, is surveyed. Finally, the review concludes by proposing challenges and opportunities for the next sustainable pyroelectric heat harvesting.

Pyroelectric materials, are those materials with the property that in the absence of any externally applied electric field, develop a built-in spontaneous polarization in their unit cell structure. They are regarded as ideal detector elements for infrared applications because they can provide fast response time and uniform sensitivity at room temperature over all wavelengths. Crystals of the perovskite Lead Titanate (PbTiO3) family show pyroelectric characteristics and undergo structural phase transitions. They have a high Curie temperature (the temperature at which the material changes from the ferroelectric (polar) to the paraelectric (nonpolar) phase), high pyroelectric coefficient, high spontaneous polarization, low dielectric constant, and constitute important component materials not only useful for infrared detection, but also with vast applications in electronic, optic, and Micro-electromechanical systems (MEMS) devices. However, the preparation of large perfect, and pure single crystals of PbTiO3 is challenging. Additionally, difficulties arise in the application of such bulk crystals in terms of connection to processing circuits, large size, and high voltages required for their operation. A number of thin film fabrication techniques have been proposed to overcome these inadequacies, among which, magnetron sputtering has demonstrated many potentials. By addressing these aspects, the review article aims to contribute to the understanding of the challenges in the field of pyroelectric materials, highlight potential solutions, and showcase the advancements and potentials of pyroelectric perovskite series including PbZrTiO3 (PZT), PbxCa1−x (PZN-PT), etc. for which PbTiO3 is the end member. The review is presented in two parts. Part 1 focuses on material aspects, including preparation methods using magnetron sputtering and material characterization. We take a tutorial approach to discuss the progress made in epitaxial growth of lead titanate-based ceramics prepared by magnetron sputtering and examine how processing conditions may affect the crystalline quality of the growing film by linking to the properties of the substrate/buffer layer, growth substrate temperature, and the oxygen partial pressure in the gas mixture. Careful control and optimization of these parameters are crucial for achieving high-quality thin films with desired structural and morphological characteristics.

In this work, explicitly pyro-catalytic performance is observed in sol-gel-synthesized ferroelectric Bi0.5Na0.5TiO3 lead-free nanomaterials, and its application for dye wastewater purification is also actualized under temperature fluctuations varying from 23 °C to 63 °C. The decomposition ratios of the pyro-catalytic Bi0.5Na0.5TiO3 nanomaterials on Rhodamine B, methyl blue and methyl orange can reach 96.75%, 98.35% and 19.97%, respectively. In the pyro-catalytic process, the probed active species such as hydroxyl radicals, superoxide radicals and holes play an extremely important role in decomposing dye molecules. The ferroelectric Bi0.5Na0.5TiO3 lead-free nanomaterials will have an excellent prospect for dye wastewater purification due to its explicit pyro-catalysis. [ABSTRACT FROM AUTHOR]

In this work, a significant enhancement of pyrocatalysis is found in barium calcium titanate @carbon (Ba 0.8 Ca 0.2 TiO 3 @C) hybrid nanofibers hydrothermally synthesized and designed to decompose rhodamine B (RhB) dye. The pure Ba 0.8 Ca 0.2 TiO 3 can decompose the RhB dye at 30–60 °C cold-hot cycles with a final decomposition ratio of 31.3%. As the content of C mixed in Ba 0.8 Ca 0.2 TiO 3 gradually increases from 0 to 5 wt%, the decomposition ratio of RhB first increases and then decreases, with the highest decomposition ratio of 76.6%, when the content of C is 3 wt%. The enhancement of pyrocatalytic activity could be attributed to the fact that the presence of C accelerates the carrier mobility and impedes the free charges recombination in the pyrocatalysis process. With the enhanced pyrocatalytic performance, Ba 0.8 Ca 0.2 TiO 3 @C hybrid nanofibers have tremendous potential for the alleviation of dye wastewater pollution through utilizing alternative cold-hot energy variation. [ABSTRACT FROM AUTHOR]

This paper describes the low temperature growth of triglycine sulphate (TGS) and deuterated l -alanine triglycine sulfate (DLaTGS) crystals using a slow cooling method. The dielectric, ferroelectric and pyroelectric properties of the grown crystals were investigated using LCR meter, Sawyer–Tower-modified circuit, and temperature ramping method, respectively. Powder X-ray diffractometer (XRD) was used to determine the crystal structure of the grown crystals. Fourier Transform Infrared (FTIR) spectroscopy was used in the range of 400–4000 cm−1 and the functional groups of the grown crystals have been identified. The results and analysis of DLaTGS detectors at 1 kHz using the black body testing station exhibit a novel behavior at room temperature with relatively low noise-equivalent power (NEP). The proposed results show a specific detectivity (D*) between (2.09–2.29) × 108 (cm Hz1/2/W) with relatively low NEP between (5.05–5.55) × 10−10 W/√Hz. Further, the temperature-dependent pyroelectric coefficient of DLaTGS detector indicates effective operation below its Curie temperature of approximately 60 °C, exhibiting pyroelectric properties ideal for various sensing and detection applications in IR region. While the proposed results of DLaTGS detectors can be used in many IR applications, including spectroscopy, remote sensing, gas analysis, thermal imaging, and medical diagnostics, one of their drawbacks is their cost. This cost can be a limiting factor for some applications, especially those that require large arrays of detectors or where cost-effectiveness is a significant concern. [Display omitted] • A Controlled temperature decrease method is used to grow TGS and DLaTGS crystals. • Slow cooling of solution is crucial for the formation of high-quality TGS and DLaTGS crystals. • The XRD patterns of undoped and doped TGS are indistinguishable from each other. • DLaTGS detectors exhibit high detectivity and a relatively low noise level. • The high cost of DLaTGS can be a limiting/factor for applications requiring large arrays or cost-effectiveness. [ABSTRACT FROM AUTHOR]

The recent burst of research on smart materials is a clear evidence of the growing interest of the scientific community, industry, and society in the field. The exploitation of the great potential of stimuli‐responsive materials for sensing, actuation, logic, and control applications is favored and supported by new manufacturing technologies, such as electrospinning, that allows to endow smart materials with micro‐ and nanostructuration, thus opening up additional and unprecedented prospects. In this wide and lively scenario, this article systematically reviews the current advances in the development of thermoactive electrospun fibers and textiles, sorting them, according to their response to the thermal stimulus. Hence, several platforms including thermoresponsive systems, shape memory polymers, thermo‐optically responsive systems, phase change materials, thermoelectric materials, and pyroelectric materials, are described and critically discussed. The difference in active species and outputs of the aforementioned categories is highlighted, evidencing the transversal nature of temperature stimulus. Moreover, the potential of novel thermoactive materials are pointed out, revealing how their development could take to utmost interesting achievements. [ABSTRACT FROM AUTHOR]

Efficient charges separation and transfer are considered to be the key factors to achieve high efficiency photoelectric catalysis. Herein, we proposed that the internal potential difference and the macroscopic polarization field of the homotype BaTiO3/CdS pyroelectric heterojunction can adjust the photoelectric catalytic performance to achieve degradation of methylene blue (MB) and rhodamine B (RhB) dyes. Under 20–50 °C hot–cold cycles, light and external bias, the catalytic rate of BaTiO3/CdS for MB is 4.82×10−2 min−1, which is 1.29 times and 1.36 times higher than photoelectric catalytic rates of BaTiO3/CdS (3.74×10−2 min−1) and BaTiO3 (2.15×10−2 min−1) alone, respectively. In addition, the catalytic rate of BaTiO3/CdS for RhB is 3.07×10−2 min−1, which is 1.41 times and 1.28 times higher than photoelectric catalytic rates of BaTiO3/CdS (2.18×10−2 min−1) and BaTiO3 (1.45×10−2 min−1) alone, respectively. The improvement of catalytic efficiency is due to the generation of pyrogenerated and photogenerated carriers, and the macroscopic polarization field and the potential difference at the BaTiO3/CdS heterojunction interface can enhance the separation and transfer of charge. This study confirms that the homotype heterojunction based on the pyroelectric effect can use solar/thermal energy to achieve efficient photoelectric catalysis. This provides a reference for the design and development of new and efficient electrodes in the field of photoelectric catalysis. [ABSTRACT FROM AUTHOR]

In this work, explicitly pyro-catalytic performance is observed in sol-gel-synthesized ferroelectric Bi0.5Na0.5TiO3 lead-free nanomaterials, and its application for dye wastewater purification is also actualized under temperature fluctuations varying from 23 °C to 63 °C. The decomposition ratios of the pyro-catalytic Bi0.5Na0.5TiO3 nanomaterials on Rhodamine B, methyl blue and methyl orange can reach 96.75%, 98.35% and 19.97%, respectively. In the pyro-catalytic process, the probed active species such as hydroxyl radicals, superoxide radicals and holes play an extremely important role in decomposing dye molecules. The ferroelectric Bi0.5Na0.5TiO3 lead-free nanomaterials will have an excellent prospect for dye wastewater purification due to its explicit pyro-catalysis.

[Display omitted] • Piezoelectric materials as drug delivery vehicles. • Smart cancer therapeutics. • Stress and temperature response for controlled release. • Targeted delivery of a drug with minimal invasive methods. Piezoelectric materials, capable of converting mechanical energy into electrical energy and vice versa, have emerged as promising candidates for designing intelligent drug delivery vehicles. Leveraging their inherent electrical properties, these materials respond to external stimuli, such as mechanical forces and electrical signals, to control drug release. By integrating piezoelectric materials into drug delivery systems, we can achieve exacting control over drug-release mechanisms. Piezoelectric materials hold enormous promise as smart delivery vehicles in cancer treatment, responding to mechanical and electrical cues, enabling site-specific drug release, reducing systemic toxicity and enhancing therapeutic effectiveness. Further advancements in the field are expected to lead to innovative piezoelectric-based systems that can revolutionize cancer treatment strategies, as explored in this review article. [ABSTRACT FROM AUTHOR]

This paper reports on direct thermal to electrical energy conversion by performing the Olsen (or Ericsson) cycle on [001]-poled 0.945PbZn1/3Nb2/3O3-0.055PbTiO3 (PZN-5.5PT) single crystals. The cycle consists of two isothermal and two constant electric field processes. The energy density was found to decrease with increasing cycle frequency while the power density increased. The maximum energy density obtained was 150 J/L/cycle for temperatures between 100 and 190oC and electric field between 0 and 1.2 MV/m at frequency 0.034 Hz. The maximum power density reached 11.7 W/L at 0.1 Hz for temperatures between 100 and 190oC and electric fields between 0.2 and 1.5 MV/m. Moreover, the dielectric constant and saturation polarization of PZN-5.5PT are reported for the first time at 0.1 Hz for temperatures between 100 and 190oC. Finally, the experimental results agree relatively well with predictions by a recently developed temperature-dependent property model already validated with PMN-32PT. Inter-sample variability and sample durability are also discussed.

Pyroelectric materials, are those materials with the property that in the absence of any externally applied electric field, develop a built-in spontaneous polarization in their unit cell structure. They are regarded as ideal detector elements for infrared applications because they can provide fast response time and uniform sensitivity at room temperature over all wavelengths. Crystals of the perovskite Lead Titanate (PbTiO3) family show pyroelectric characteristics and undergo structural phase transitions. They have a high Curie temperature (the temperature at which the material changes from the ferroelectric (polar) to the paraelectric (nonpolar) phase), high pyroelectric coefficient, high spontaneous polarization, low dielectric constant, and constitute important component materials not only useful for infrared detection, but also with vast applications in electronic, optic, and Micro-electromechanical systems (MEMS) devices. However, the preparation of large perfect, and pure single crystals of PbTiO3 is challenging. Additionally, difficulties arise in the application of such bulk crystals in terms of connection to processing circuits, large size, and high voltages required for their operation. A number of thin film fabrication techniques have been proposed to overcome these inadequacies, among which, magnetron sputtering has demonstrated many potentials. By addressing these aspects, the review article aims to contribute to the understanding of the challenges in the field of pyroelectric materials, highlight potential solutions, and showcase the advancements and potentials of pyroelectric perovskite series including PbZrTiO 3 (PZT), PbxCa1-x (PZN-PT), etc. for which PbTiO3 is the end member. The review is presented in two parts. Part 1 focuses on material aspects, including preparation methods using magnetron sputtering and material characterization. We take a tutorial approach to discuss the progress made in epitaxial growth of lead titanate-based ceramics prepared by magnetron sputtering and examine how processing conditions may affect the crystalline quality of the growing film by linking to the properties of the substrate/buffer layer, growth substrate temperature, and the oxygen partial pressure in the gas mixture. Careful control and optimization of these parameters are crucial for achieving high-quality thin films with desired structural and morphological characteristics.

Pyroelectric performance of the composites of plaster of Paris (POP) and the lead-free Sr0.5Ba0.5Nb2O6 (SBN) ceramic have been studied in this paper. SBN-POP composites with 30, 40, 50, and 60% SBN content by weight referred as SBN30, SBN40, SBN50, and SBN60 have been studied. The dielectric constants for SBN30, SBN40, SBN50, and SBN60 composites are obtained as 10.51, 21.62, 43.61, and 57, respectively at room temperature (25 °C). The maximum open-circuit voltages in the range of 31 to 103 mV could be obtained by subjecting the SBN-POP composite samples to temperature gradient by blowing hot and cold air. Further maximum voltages in the range of 8 to 34 mV and maximum current in the range of 2.9 to 18 nA could be obtained across 1 MΩ resistance. The SBN-POP composites seem to be suitable candidate to be used as pyroelectric sensors. [ABSTRACT FROM AUTHOR]

With increasing emphasis on implantable and portable medical devices, low-power, small-chip-area sensor readout systems realized in lab-on-a-chip (LOC) platforms are gaining more and more importance. The main building blocks of the LOC system include a front-end transducer that generates an electrical signal in response to the presence of an analyte of interest, signal processing electronics to process the signal to comply with a specific transmission protocol, and a low-power transmitter, all realized in a single integrated circuit platform. Low power consumption and compactness of the components are essential requirements of the LOC system. This brief presents a novel charge sensitive pre-amplifier developed in a standard 180-nm CMOS process suitable for implementing in an LOC platform. The pre-amplifier converts the charge generated by a pyroelectric transducer into a voltage signal, which provides a measurement of the temperature variation in biological fluids. The proposed design is capable of providing 0.8-mV/pC gain while consuming only $2.1~{\mu }\text{W}$ of power. The pre-amplifier composed of integrated components occupies an area of 0.038 mm2. [ABSTRACT FROM AUTHOR]

Abstract: A large gain in pyroelectric voltage and current when exposed to infrared radiation after candle soot coating on material surfaces is reported. A piezoelectric buzzer is selected to quantify the effect of candle soot on pyroelectric output. For a given temperature change, the peak value of the open‐circuit voltage is enhanced from 2 V to 8 V and electric current is boosted from 15 nA to 95 nA. A load capacitor is also connected through a full wave rectifier. Energy storage in a 10 μF load capacitor is increased from 5 nJ to 70 nJ. [ABSTRACT FROM AUTHOR]

Abstract: The thermal energy harvesting potential of different pyroelectric materials including Sr0.5Ba0.5Nb2O5 (SBN), [Bi0.48Na0.4032K0.0768] Sr0.04(Ti0.975Nb0.025)O3 (BNT‐Nb), Ba0.85Sr0.15Zr0.1Ti0.9O3 (BST‐BZT), Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCT‐BZT), and Ba0.9Ca0.1TiO3 (BCT) ceramics is compared. Amongst these materials, BCT is found to be best for pyroelectric energy harvesting. Open‐circuit voltages were found to be 1.7 V, 500 mV, 650 mV, 600 mV, and 400 mV for BCT, SBN, BCT‐BZT, BST‐BZT, and BNT‐Nb, respectively. BCT is further analyzed, revealing an optimum power output of 0.072 μW at the optimized cycle frequency (0.06 Hz) and at a load resistance of 18 MΩ. To improve the effectiveness of energy conversion from heat to electricity, the synchronized switch harvesting on inductor (SSHI) technique is experimentally tested on a BCT sample. It is revealed that this concept based on SSHI can significantly increase the amount of power extracted from pyroelectric materials. Compared with 0.072 μW across a standard circuit in a BCT sample, an enhanced power output of 0.16 μW and 0.14 μW is obtained using parallel and series SSHI, respectively at 0.06 Hz. The results reveal that the non‐linear processing technique based on SSHI leads to significant power improvement compared to non‐switched interface. [ABSTRACT FROM AUTHOR]

Abstract: The pyroelectric performance of Pb0.99Nb0.02[(Zr0.57Sn0.43)0.92Ti0.08]0.98O3 ceramics was quantified by dielectric, polarization, and specific heat capacity measurements. The tunability of pyroelectric properties upon electric field application was studied as a function of temperature. The large pyroelectric coefficient of 0.28 C m−2 K−1 was associated with the ferroelectric (FE)–antiferroelectric (AFE) phase transition. The pyroelectric coefficient can be tuned over a broad temperature range of almost 40 K above the zero electric field phase transition. Electrical and thermal measurements were used to estimate various pyroelectric figures of merit. Pyroelectric figures of merit are almost three order of magnitude higher than those previously reported in FE materials. The large pyroelectric properties indicate that the investigated material is a promising candidate for many pyroelectric applications. [ABSTRACT FROM AUTHOR]

Among the various forms of natural energies, heat is the most prevalent and least harvested energy. Scavenging and detecting stray thermal energy for conversion into electrical energy can provide a cost-effective and reliable energy source for modern electrical appliances and sensor applications. Along with this, flexible devices have attracted considerable attention in scientific and industrial communities as wearable and implantable harvesters in addition to traditional thermal sensor applications. This review mainly discusses thermal energy conversion through pyroelectric phenomena in various lead-free as well as lead-based ceramics and polymers for flexible pyroelectric energy harvesting and sensor applications. The corresponding thermodynamic heat cycles and figures of merit of the pyroelectric materials for energy harvesting and heat sensing applications are also briefly discussed. Moreover, this study provides guidance on designing pyroelectric materials for flexible pyroelectric and hybrid energy harvesting.

We deal with the thermal energy which is one of the ambient energy sources surely exploitable, but it has not been much interest as the mechanical energy. In this paper, our aim is to use thermal energy and show that it’s an important source for producing the electrical energy through pyroelectric effect which is the property of some dielectric materials to show a spontaneous electrical polarization versus temperature. In this context, we present a concept to harvest a thermal energy using infrared rays and pyroelectric effect. The pyroelectric material used in this work can generate an electrical voltage when it subjected to a temperature change which will be ensured by the use of infrared lamp. Our experimental results show that the electrical voltage, current and harvested power increased significantly when increasing the area of the pyroelectric element. The experimental results show also that with this simple concept we harvested a heavy amount value of power which will certainly be useful in an extensive range of applications, including sensors and infrared detection. These results shed light on the thermoelectric energy conversion by Ceramic lead zirconate titanate (PZT) buzzer having the pyroelectric property. [ABSTRACT FROM AUTHOR]

The efficient separation and transfer of electrons-holes is a key problem in photoelectric catalysis. Herein, oxygen vacancies are introduced into BaTiO 3 and combined with pyroelectric polarization to regulate the photoelectric catalytic performance, improving the separation efficiency of carriers. Under 20–50 °C hot-cold cycle, illumination and bias, the maximum current density of BaTiO 3−X -5% after oxygen vacancies introduced is 0.77 mA·cm−2, which is higher than the current density of BaTiO 3 under light alone (0.17 mA·cm−2), and the current density of BaTiO 3 under temperature fluctuation and light (0.35 mA·cm−2). This is because oxygen vacancies are characterized by prolonged light absorption and improved the use utilization of solar energy, it can be used as the capture center of excited electrons to inhibit excited electron-hole pairs recombination. In addition, the generation of photogenerated and pyrogenerated carriers increases the total carrier concentration, and the formation of polarized electric field promotes the separation and transfer of carriers. This offers an idea for development of high performance photoelectrodes in photoelectric catalytic water splitting. [Display omitted] • Pyro-photo-electric catalysis of BaTiO 3 pyroelectric materials with oxygen vacancies is studied in water splitting. • The PEC performance of BaTiO 3 is improved with the assist of pyroelectric effect and oxygen vacancies. • Oxygen vacancies can improve solar energy utilization and inhibit carrier recombination as electron capture centers. • Polarization field of pyroelectric effect promotes the separation and transfer of carriers. • Pyroelectric assisted photoelectric catalysis can realize the utilization of thermal and solar energy. [ABSTRACT FROM AUTHOR]

In an effort to harvest thermal energy and exploit abundantly available waste heat the pyroelectric effect offers the opportunity to convert temperature fluctuations into useable electrical energy. Here, the micropatterning of the surface of a pyroelectric in order to enhance heat transfer and achieve faster and larger temperature fluctuations, which improve pyroelectric energy transformation, is reported. Methods for the fabrication of partially covered electrodes on polyvinylidene difluoride (PVDF) films are developed to investigate and quantify the benefits of such an electrode structure for pyroelectric energy harvesting. The micropattern consists of an array of holes that are etched into the upper aluminum electrodes of free standing ferroelectric PVDF films using a low cost photolithography and wet etching process. Under the application of infrared radiation heating, it is demonstrated that such microfeatures are able to significantly improve the open circuit voltage by 380% and the closed circuit current by 420% for an electrode area coverage of 45% when compared to a fully covered electrode design. Capacitance measurements show constant electric fields with microfeatures for electrode area coverages as low as 28%. A specific generator performance of 66.9 μJ cm−3 cycle−1 is presented at oscillation temperatures of 2.8 °C. [ABSTRACT FROM AUTHOR]

The energy conversion and harvesting properties of pyroelectric devices depend on many aspects, including the properties of pyroelectric materials, the structure of the devices, and so on. In this work, the capability of harvesting energy using Pb[(Mn x Nb 1− x ) 1/2 (Mn x Sb 1− x ) 1/2 ] y (Zr z Ti 1− z ) 1− y O 3 (PMnN–PMS–PZT) ceramics was studied. For this purpose, three different Zr/Ti compositions, i.e. 94/6, 95/5 and 96/4 (in molar ratio) of the ceramics were prepared and characterized. The ceramic with 95/5 of Zr/Ti was found to have optimized pyroelectric properties and consequently used to fabricate pyroelectric energy harvesting devices. Three different device configurations, including a monolithic ceramic, ceramic arrays and multilayered ceramics were studied, and the innovated multilayered ceramic structure proposed in this study showed advantages in energy conversion and collection efficiency, which were evaluated by using an oven and a Peltier cell as heating and cooling methods. The maximum densities of surface charge achieved for the three types of ceramic structures are 7.19 × 10 −6 C/cm 2 , 6.59 × 10 −6 C/cm 2 , 1.55 × 10 −5 C/cm 2 , respectively, which are in general higher than that of the commercial lead zirconate titanate (PZT-5H). We also investigated the effects of temperature change frequency on the electrical response by using the monolithic ceramic device as an example. At an operating frequency of 70 mHz, the pyroelectric device shows an induced energy as high as 2.873 μJ and a power density of 4.857 mW/cm 3 . The obtained results indicate that our proposed PMnN–PMS–PZT devices in general has a better pyroelectric performance than the commercial lead zirconate titanate (PZT-5H) pyroelectric devices, and may have potential applications in ultra-low-power devices and in wireless network systems. [ABSTRACT FROM AUTHOR]

As low-carbon and smart cities are recently developing fast, non-intrusive and movable energy harvesters can be a trend of energy harvester development to face the severe climate change and to follow the fast pace of urban development and energy needs. To study the feasibility of developing non-intrusive and movable energy harvesters within the limit area available on transportation infrastructures (e.g., roadway, bridge, pipeline), advanced energy materials and the innovative energy harvester designs have been extensively reviewed, identified, and analzyed. For the energy material selection, the review covers the development of photovoltaic materials, thermoelectric materials, piezoelectric materials, and pyroelectric materials. It shows significant relevant progresses, which have reached the theoretical limitations of their energy harvesting performance. On the other side, this review collects a series of relevant innovative designs, including concentrating solar power devices, portable solar panels, horizontal wind turbines, piezoelectric-based (or pyroelectric-based) wind energy harvesters, and vibration-based piezoelectric harvesters. Based on their sizes, power outputs, and external environmental requirements, it is clear that some non-intrusive and movable energy harvesters can be quickly implemented on transportation infrastructures for producing considerable power outputs. As a result, through critically assessing current developments of all relevant advanced materials with innovative designs, a new research direction is explored to develop movable and non-intrusive energy harvesters suitable for transportation infrastructures. • Critically reviewed advanced material developments for energy harvesting. • Discussed innovative designs of non-intrusive and movable energy harvesters. • Proposed potential use of energy harvesters on transportation infrastructures exposed to live loading and environment. [ABSTRACT FROM AUTHOR]

Highlights: [•] Demonstration of a novel cycle converting thermal and mechanical energy directly into electrical energy. [•] The new cycle is adaptable to changing thermal and mechanical conditions. [•] The new cycle can generate electrical power at temperatures below those of other pyroelectric power cycles. [•] The new cycle can generate larger electrical power than traditional mechanical cycles using piezoelectric materials. [ABSTRACT FROM AUTHOR]

• Pyro-photo-electric catalysis of Bi 2 WO 6 is firstly studied in organic dyes. • The polarized field generated by pyroelectric effect promotes the separation and transfer of photo-generated carriers. • The carrier concentration is the highest in the process of pyro-photo-electric catalysis. • The dual catalysis is better than pyro-electric catalysis or photo-electric catalysis in dyes degradation. • It has the potential of Bi 2 WO 6 in the use of thermal/solar/electric energy to degrade pollutant. [Display omitted] The severe recombination of photo-generated carriers is a key issue that restricts the development of photo-electric catalysis technology. Herein, it is proposed for the first time to utilize the polarization field of Bi 2 WO 6 pyroelectric materials to adjust the photo-electric catalysis performance to achieve the degradation of dyes such as methylene blue (MB) and rhodamine B (RhB). Under 20–45 °C alternating hot and cold, light illumination and external bias, the catalytic rate of Bi 2 WO 6 for MB is 3.06 × 10−2 min−1 which respectively increases by 2.14 and 13.85 times compared with photo-electric catalysis (9.731 ×10−3 min−1) and pyro-electric catalysis (2.06 ×10−3 min−1), and the catalytic rate of Bi 2 WO 6 for RhB is 1.96 × 10−2 min−1 which respectively increases by 1.04 and 11.35 times compared with photo-electric catalysis (9.60 ×10−3 min−1) and pyro-electric catalysis (1.59 ×10−3 min−1). The improvement in catalysis efficiency is originated from the increased carrier concentration caused by the combination of pyro-generated carriers and photo-generated carriers, and the polarized built-in electric field. This study proves that Bi 2 WO 6 pyroelectric materials can be used for photo-electric catalysis degradation of pollutants by utilization of a variety of clean energy including solar energy, thermal energy and electrical energy simultaneously, which provides a critical idea for the design of new environmentally friendly electrodes for catalytic degradation. [ABSTRACT FROM AUTHOR]

Abstract: In the last decades the development of new satellite platforms from a smaller to a bigger size goes in parallel with the development of the microelectronics equipment boarded on. Avionics, control systems and payloads equipment exploit the microelectronics in order to reduce the overall dimensions and masses and to increase the performances of each unit for the improvement of goals in each mission. A larger use of electronic elements with the relevant components increases the importance of a carefully equipment designed under different points of view. One of them is the thermal management. It is well known that the Joule Effect causes the heat overstocking which in turn reduces the efficiency of the electronic devices and increases the difficulties to manage the thermal power budget on board. A new design philosophy sees a possibility for a simpler and a more efficient thermal control on the use of the pyroelectric materials. Pyroelectrics are a “special” class of materials that demonstrates a spontaneous capacity to convert thermal fluxes in electrical charge and if applied on a “passive” structure they can “actively” reduce the heat overstocking. The electrical charge could be eventually stored for different purposes such as for instance the auto-feeding, or better the energy harvesting. With the reduction of the temperature of each component, and consequently with the reduction of the heat flux that flows through microelectronics, better efficiency and better performances are ensured. In this way the reliability is increased and the goals of the mission could be achieved easier and easier. In this paper the design of a thermal rig made up of pyroelectric devices and dummy electronics components in order to verify the thermo-electric conversion is presented. Furthermore an experimental campaign has been performed to validate the technology here introduced and the relevant results presented. In particular the characterisation of a typical aerospace pyroelectric material via scanning electron microscope (SEM) and a semi-quantitative analysis will be discussed. In order to verify the trustworthiness of the experimental campaign the results will be compared with the ones coming from an in-house-developed numerical code. [Copyright &y& Elsevier]

Abstract: This paper reports numerical simulations of a prototypical pyroelectric energy converter as a novel approach for directly converting waste heat into electricity. The two-dimensional mass, momentum, and energy equations were solved to predict the local time-dependent pressure, velocity, and temperature. Then, heat input, pumping power, and electrical power generated were estimated, along with the thermodynamic energy efficiency and power density of the device. It was established that reducing the length of the device and/or the viscosity of the working fluid improved the energy efficiency and power density of the device by increasing the optimum operating frequency. Results show that a maximum efficiency of 5.2% at 0.5Hz corresponding to 55.4% of the Carnot efficiency between 145 and 185°C can be achieved with commercial 1.5cst silicone oil as the working fluid and PZST as the pyroelectric material. The associated power density was found to be 38.4W/L of material. [Copyright &y& Elsevier]

This study investigates the feasibility of heat energy harvesting using pyroelectric effect. In order to improve the effectiveness of the energy conversion from heat to electricity, the synchronized switch harvesting on inductor (SSHI) (Guyomar et al., 2005) technique is experimentally tested, which has already proved its quality in electromechanical conversion. For several amplitude variations of temperature from 0.5 to 8.0 K, the conversion efficiency is found about 0.02% of Carnot thermodynamic cycle with a standard interface. Under the same heating conditions, experimental results show that the SSHI technique increases the converted energy by a factor which is about 2.5 times of the standard interface, with which the efficiency practically becomes 0.05% of Carnot thermodynamic cycle. In this case, the produced electrical power for temperature amplitude 7K is more than 0.3mW for an energy harvesting device composed of 8 g of active material. The main power limitation is due to temperature frequency. Low speed of heat transfer makes it difficult to obtain fast temperature variations with large amplitude. [ABSTRACT FROM AUTHOR]

The pyroelectric coefficient of 0-3 composites of ferroelectric ceramic particles in a polymer matrix can be increased drastically by introducing a specified dc conductivity as explained by predictions based on the Poon-Shin model. The influence of doping with lithium chlorate on the dielectric permittivity of polyurethane has been studied to identify proper process parameters for the doping of composites. After appropriate doping the pyroelectric coefficient of 0-3 PZT/polyurethane composite is increased by more than a factor of ten at frequencies around 50 Hz. [ABSTRACT FROM AUTHOR]

Ba0.65Sr0.35(Ti0.95Sn0.05)O3 (BSTS) ferroelectric thin films are prepared by means of the sol-gel method on the Pt/Ti/SiO2/Si substrate. The results of the atomic force microscopy and X-ray diffraction analysis indicate that the grain sizes of BST thin films does not cause the change with the doped Sn. Compared with Ba0.65Sr0.35TiO3 (BST) thin films, BSTS thin films possess a lower dielectric constant and loss tangent, which is propitious to the improvement of the figures of merits of pyroelectric materials. The polarization at E = 0 and the field at P = 0 of BSTS thin films are 1.35 μ C/cm2 and 12.89 kV/cm, respectively. [ABSTRACT FROM AUTHOR]

To obtain an optimum coupling of the pyroelectric activity of ferroelectric inclusions to the electrodes of a 0–3 composite film, the dielectric constants of matrix material and inclusions would have to be comparable. While there is no way to substantially raise the real part of the dielectric constant of the polymer matrix, the imaginary part can be increased by an appropriate doping. The results from theoretical modelling predict a significant increase of the pyroelectric coefficient and especially the pyroelectric signal power. Experimental investigations on composites of lead titanate particles in polyurethane doped with potassium bromide show the improvement and give hints to further optimization of its pyroelectric performance. [ABSTRACT FROM AUTHOR]

To improve the coupling of the pyroelectric activity of the ferroelectric particles to the electrodes of a composite film we propose the use of a matrix material which is not a perfect insulator but shows some electric conduction. Theoretical modelling results show that the pyroelectric coefficient of these composites is drastically enhanced. Furthermore, the noise figure of merit can be optimized by a proper selection of the electric conductivity of the polymer matrix. For the practical application in a sensor, these new composites have the additional advantage that the gate voltage of the first field effect transistor can be supplied through the resistance of the pyroelectric sensor element. [ABSTRACT FROM AUTHOR]

Abstract: Single crystals of triglycine sulfate (TGS) doped with D-phenylalanine and with Pt(IV) ions (PATGS/Pt(IV)) were grown from aqueous solution by means of the slow cooling method. On the samples prepared from 〈110〉 and growth pyramids we measured the relevant physical properties, in particular: spontaneous polarization Ps, values of coercive field Ec, internal electrical field Eb, dielectric permittivity εr, dielectric losses tanδ and hysteresis loops. The first series of pyroelectric detectors were prepared from these materials; their fundamental parameters are presented. [Copyright &y& Elsevier]

A simplified photopyroelectric (PPE) configuration that allows the simultaneous determination of the temperature dependent thermal and pyroelectric parameters of pyroelectric materials is described. The thermal parameters (thermal diffusivity, conductivity, effusivity and volumic specific heat) are obtained from the analysis of the phase of the complex photopyroelectric (PPE) signal generated from the pyroelectric sample itself and measured for two different modulation frequencies. The pyroelectric coefficient is obtained from the amplitude of the signal. Experimental results on thermal and pyroelectric parameters of LiTaO 3 single crystal in the 25°C-70°C temperature range are reported. [ABSTRACT FROM AUTHOR]

As one important subclass of piezoelectric materials, pyroelectric materials have caused increasing attention owing to the unique pyroelectric effect induced by spontaneous polarization, showing broad promising application prospects due to various electrical responses induced by time-dependent temperature variation. This review systematically introduces the pyroelectric effect and evaluation of pyroelectric materials and follows by analyzing and concluding the novel properties corresponding to four kinds of main pyroelectric materials. The emphasis of this review focuses on several significant and practical applications of pyroelectric materials in thermal energy harvesting from the external environment, pyroelectric sensing, and imaging, even some electrochemical applications including hydrogen generation, wastewater treatment, sterilization, and disinfection. Finally, the development direction of pyroelectric materials, potential challenges and opportunities in the future are all discussed and proposed. Through systematical conclusion and analysis of the latest research progress in the recent two decades, this review may provide significant guide and inspiration in the development of pyroelectric materials., (© 2021 Wiley-VCH GmbH.)

Among the various forms of natural energies, heat is the most prevalent and least harvested energy. Scavenging and detecting stray thermal energy for conversion into electrical energy can provide a cost-effective and reliable energy source for modern electrical appliances and sensor applications. Along with this, flexible devices have attracted considerable attention in scientific and industrial communities as wearable and implantable harvesters in addition to traditional thermal sensor applications. This review mainly discusses thermal energy conversion through pyroelectric phenomena in various lead-free as well as lead-based ceramics and polymers for flexible pyroelectric energy harvesting and sensor applications. The corresponding thermodynamic heat cycles and figures of merit of the pyroelectric materials for energy harvesting and heat sensing applications are also briefly discussed. Moreover, this study provides guidance on designing pyroelectric materials for flexible pyroelectric and hybrid energy harvesting. [ABSTRACT FROM AUTHOR]