Advantages of obliquely cut TGS crystals in pyroelectric applications

Shaulov, A.; Smith, W.A.; Rao, N. Venkat

doi:10.1080/00150198108209593

Cited by 5 publications

(1 citation statement)

References 4 publications

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“…This approach controls the morphology, structure, and size of the nanocrystals through the template's material properties and structure. This approach is, however, limited in its success, as far as TGS is concerned, which is also used within this study: it turns out that a porous thin film can be used as a matrix for crystal growth, however the crystallographic orientation of the pyroelectric material deposited in the matrix is random which decreases the pyroelectric response in comparison to well-oriented single crystals [12].…”

Section: Introductionmentioning

confidence: 99%

A pyroelectric thin film of oriented triglycine sulfate nano-crystals for thermal energy harvesting

Ghane-Motlagh

Woias

2019

Smart Mater. Struct.

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This study introduces a method for the fabrication of transparent and flexible pyroelectric thin films containing oriented triglycine sulfate (TGS) nanorods for thermal energy conversion or thermal sensing. For the fabrication of such thin films a highly nanoporous anodic aluminum oxide (AAO) template is mounted on top of a b-cut TGS seed crystal before filling the template’s nanopores with TGS solution. Crystal growth in the filled pores is done via the so-called temperature-lowering technique. Two principles are applied to grow oriented nanocrystals in the AAO template: first, the effect of different crystal growth rates in different directions of a nanopore’s confined space is exploited. Second, crystal growth at the bottom of the pores is initiated in a preferential direction by the TGS seed crystal. As confirmed by x-ray diffraction the crystal nanorods obtained are oriented in the desired spontaneous polarization vector of TGS (b-direction). Optical transparency of the filled AAO thin film is good when compared to a pure AAO film which indicates a reasonably high homogeneity and a reasonably low defect density of the TGS nanocrystals. Dielectric characterization at 1 kHz shows a relative permittivity similar to a bulk TGS crystal and a high resistivity of about 199 MΩ m. At its phase transition temperature (44 °C), the dielectric loss factor of the thin film is about 0.3. An average pyroelectric coefficient of 133 μC m−2 K−1 and a relative permittivity of 15.6 are calculated from measurement results at room temperature, taking the effect of the AAO thin film into account. With that, the pyroelectric voltage figure of merit (FOM) (pc/εrε0) and the energy harvesting FOM (pc2/εrε0) and are about 820 kV m−1 K−1 and 72 J m−3 K−2, respectively. In comparison to other approaches for growing thin films of oriented TGS crystals, the described method exhibits advantages concerning the growth of oriented nanocrystals, simplicity, fast growth, and an access to both sides of the nanocrystals.

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Section: Introductionmentioning

confidence: 99%

A pyroelectric thin film of oriented triglycine sulfate nano-crystals for thermal energy harvesting

Ghane-Motlagh

Woias

2019

Smart Mater. Struct.

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Pyroelectric infrared detectors and materials—A critical perspective

Whatmore

Ward

2023

Journal of Applied Physics

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Pyroelectric infrared detectors (PIRDs) have a number of advantages over other IR sensors, including room-temperature operation, wide wavelength sensitivity, and low cost, leading to their use in many applications and a market expected to reach U.S.$68 million by 2025. Physical models that can be used to accurately predict the performances of PIRDs of different types are reviewed in detail. All polar dielectrics exhibit the pyroelectric effect, so there are many materials potentially available for use in PIRDs. Traditionally, a range of “figures-of-merit” (FoMs) are employed to aid the selection of the best material to use in a given application. These FoMs, and their utility in determining how a given pyroelectric material will behave in a PIRD, are reviewed in the light of the physical models and the availability of dielectric data, which cover the frequency ranges of greatest interest for PIRDs (0.1–100 Hz). The properties of several pyroelectric materials are reviewed, and models are derived for their dielectric properties as functions of frequency. It is concluded, first, that the availability of full-frequency dielectric data is highly desirable if accurate predictions of device performance are to be obtained from the models and that second, the FoMs have practical utility in only very limited circumstances. Thus, they must be used with considerable care and circumspection. The circumstances under which each FoM is likely to give a good prediction for utility are discussed. The properties of some recently researched pyroelectric materials, including lead-containing single crystals in the Pb[(Mg⅓Nb⅔)xTi1−x]O3 system and Na½Bi½TiO3–K½Bi½TiO3 based lead-free crystals and ceramics, are reviewed in the light of this, and their properties and potential for device applications compared with the industry-standard material, LiTaO3. It is concluded that while there is potential for significant device performance improvements by using improved materials, especially with the PMN-PT-based materials, factors such as temperature stability, uniformity, and ease-of-processing are at least as important as device performance in determining material utility. The properties reported for the new lead-free materials do not, as yet, promise a performance likely to compete with LiTaO3 for mm-scale detectors, a material that is both readily available and lead-free.

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Optimum cuts of monoclinic m crystals for pyroelectric detectors

Shaulov

Smith

1983

Ferroelectrics

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An analysis of pyroelectric figures of merit in oblique cuts of crystals belonging to the symmetry class m is presented. It is shown that the optimum cut and the gain depend on the dielectric anisotropy and the orientation of the pyroelectric axis with respect to the dielectric principal axes. Remarkable enhancements are possible in optimum cuts of crystals with large anisotropy ratio in the mirror plane and large deviation of the pyroelectric axis from the principal axes of the dielectric tensor.

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Advantages of obliquely cut TGS crystals in pyroelectric applications

Cited by 5 publications

References 4 publications

A pyroelectric thin film of oriented triglycine sulfate nano-crystals for thermal energy harvesting

A pyroelectric thin film of oriented triglycine sulfate nano-crystals for thermal energy harvesting

Pyroelectric infrared detectors and materials—A critical perspective

Optimum cuts of monoclinic m crystals for pyroelectric detectors

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