Brian C Riggs - Academia.edu (original) (raw)
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National Physical Laboratory, New Delhi, India
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Papers by Brian C Riggs
We investigated structural, aging induced ferroelectric, piezoelectric and energy density propert... more We investigated structural, aging induced ferroelectric, piezoelectric and energy density properties of ceramic (Ba 0.70 Ca 0.30 )TiO 3 (BCT) capacitors that were prepared by the solid-state reaction method. According to X-ray (XRD) data, along with BaTiO 3 tetragonal peaks, CaTiO 3 rich orthorhombic peaks were also observed at room temperature. Raman scattering gives evidence for the formation of oxygen vacancies in BCT due to partial migration of Ca 2+ into Ti 4+ site. Abnormal double like hysteresis polarizationelectric field (P-E) loops were observed at room temperature for naturally aged BCT ceramics. Strain-electric field (S-E) loops confirm piezoelectric behavior. Room temperature (300 K) charge curve and discharge curve energy densities [(Ed) c $ 0.35 (before aging) 0.39 J/cm 3 (aged)], [(Ed) d $ 0.20 (before aging) 0.24 J/cm 3 (aged)], respectively, at a maximum electric field 50kV/cm.ThebulkBCTmaterialshaveshowninterestingenergydensitieswithgoodenergystorageefficiency(50 kV/cm. The bulk BCT materials have shown interesting energy densities with good energy storage efficiency (50kV/cm.ThebulkBCTmaterialshaveshowninterestingenergydensitieswithgoodenergystorageefficiency(58% before aging, $61% after aging) suggesting they might be strong candidates for high energy density capacitor applications.
To meet the rising need for on-demand electric energy, dielectric capacitors have been of increas... more To meet the rising need for on-demand electric energy, dielectric capacitors have been of increasing interest owing to their unique energy storage properties. The ability to deliver large amounts energy near instantaneously with a simple device that can last over millions of cycles is making dielectric capacitors one of the most attractive future options for large-scale electrical energy storage. The low gravimetric energy density, however, has prevented its widespread application in a wide range of fields including electric vehicles, and personal power technologies. Ceramic and polymer materials are being developed for energy storage, however, intrinsic limits on their dielectric properties (e.g., breakdown field and dielectric constant, respectively) prevents them from being used for high energy density applications. Because of this, composite systems of ceramics and polymers have been of increasing interest as they hold the potential for simultaneous improvement of both the dielectric constant and breakdown field leading to significant improvements in the energy storage potential. Herein we present new results and discuss the state of dielectric capacitor research including a discussion of the properties of interest. Recent developments in the field will be discussed including improvements in material properties, processing, and interface issues that arise when compositing materials as well as solutions to overcome these obstacles.
We investigated structural, aging induced ferroelectric, piezoelectric and energy density propert... more We investigated structural, aging induced ferroelectric, piezoelectric and energy density properties of ceramic (Ba 0.70 Ca 0.30 )TiO 3 (BCT) capacitors that were prepared by the solid-state reaction method. According to X-ray (XRD) data, along with BaTiO 3 tetragonal peaks, CaTiO 3 rich orthorhombic peaks were also observed at room temperature. Raman scattering gives evidence for the formation of oxygen vacancies in BCT due to partial migration of Ca 2+ into Ti 4+ site. Abnormal double like hysteresis polarizationelectric field (P-E) loops were observed at room temperature for naturally aged BCT ceramics. Strain-electric field (S-E) loops confirm piezoelectric behavior. Room temperature (300 K) charge curve and discharge curve energy densities [(Ed) c $ 0.35 (before aging) 0.39 J/cm 3 (aged)], [(Ed) d $ 0.20 (before aging) 0.24 J/cm 3 (aged)], respectively, at a maximum electric field 50kV/cm.ThebulkBCTmaterialshaveshowninterestingenergydensitieswithgoodenergystorageefficiency(50 kV/cm. The bulk BCT materials have shown interesting energy densities with good energy storage efficiency (50kV/cm.ThebulkBCTmaterialshaveshowninterestingenergydensitieswithgoodenergystorageefficiency(58% before aging, $61% after aging) suggesting they might be strong candidates for high energy density capacitor applications.
To meet the rising need for on-demand electric energy, dielectric capacitors have been of increas... more To meet the rising need for on-demand electric energy, dielectric capacitors have been of increasing interest owing to their unique energy storage properties. The ability to deliver large amounts energy near instantaneously with a simple device that can last over millions of cycles is making dielectric capacitors one of the most attractive future options for large-scale electrical energy storage. The low gravimetric energy density, however, has prevented its widespread application in a wide range of fields including electric vehicles, and personal power technologies. Ceramic and polymer materials are being developed for energy storage, however, intrinsic limits on their dielectric properties (e.g., breakdown field and dielectric constant, respectively) prevents them from being used for high energy density applications. Because of this, composite systems of ceramics and polymers have been of increasing interest as they hold the potential for simultaneous improvement of both the dielectric constant and breakdown field leading to significant improvements in the energy storage potential. Herein we present new results and discuss the state of dielectric capacitor research including a discussion of the properties of interest. Recent developments in the field will be discussed including improvements in material properties, processing, and interface issues that arise when compositing materials as well as solutions to overcome these obstacles.