Amar S. Bhalla

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Structural health monitoring (SHM) is an emerging field in which smart materials interrogate structural components to predict failure, expedite needed repairs, and thus increase the useful life of those components. Piezoelectric wafer active sensors (PWAS) have been previously adhesively-bonded to structures and demonstrate the ability to detect and locate(More)
The dielectric behavior of the pyrochlore (Bi3/4Zn1/4)2(Zn1/4Ta3/4)2O7 compound has been studied. A low-temperature dielectric relaxation was observed in a low-permittivity matrix with «5;60. The dielectric relaxation process follows a modified Debye model in the vicinity of the relaxation peak, and the relaxation rate follows the Arrhenius law in the wide(More)
The field distribution, dielectric constant, and loss in a two-phase composite, in which phase A is distributed inside a square matrix of phase B, have been calculated using the finite-element method ~FEM!. The calculation was carried out by taking into account different shapes for phase A, such as circles, triangles, and rings with different sizes. The(More)
The dielectric and pyroelectric properties of triglycerol-gelatin thick films were studied as a function of temperature and frequency. The films exhibited a strong dispersion in the dielectric permittivity accompanied by a high dielectric loss near room temperature. The pyroelectric current measured by the static Byer-Roundy method is heavily dominated by(More)
The dielectric behavior of SrTiO3 single crystals under high dc electric field ~up to 50 kV/cm! is reported in this letter. The rounded dielectric constant peaks are induced by the application of dc bias, and the corresponding dielectric losses are observed. The results show that dielectric loss under dc bias consists of several components coming from(More)
The effect of dc electric field and post-treatment on the dielectric properties of SrTiO3 single crystals are reported. Both the dielectric constant and the loss tan d decrease after post-treatment in flowing oxygen environment for 26 h at 1100 °C. The possible physical mechanism is briefly discussed. The dielectric behavior under dc electric field is(More)
The dc electric-field dependence of dielectric constant in the paraelectrics, KTaO3 single crystals, CaTiO3 and (Ln1/2Na1/2)TiO3 (Ln5La and Nd! ceramics is studied at cryogenic temperatures in the dc electric-field range 0–60 kV/cm. The results indicate that KTaO3 possesses a high tunability K$5@e(E0)2e(E)#/e(E0) 5;50%% at 20 kV/cm, and low dielectric loss(More)
We report on the fabrication of ferroelectric BaTiO3 thin films on titanium substrates using pulsed laser deposition and their microstructures and properties. Electron microscopy studies reveal that BaTiO3 films are composed of crystalline assemblage of nanopillars with average cross sections from 100 nm to 200 nm. The BaTiO3 films have good interface(More)
The doping effect on the structural, microstructural and dielectric properties of bismuth layer structured SrBi<sub>2</sub>Nb<sub>2</sub>O<sub>9</sub>(SBN) ferroelectric ceramics has been investigated. The samples were obtained from the solid state reaction sintering method. Particularly, the A-site cation substitution of Sr<sup>2+</sup> by La<sup>3+</sup>(More)