Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 14 of 14 for “"d33"”.
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Uniform-electric-field-approximation based modelling of longitudinal piezoelectric transducers
… in principle, be divided into d31-mode LPT and d33-mode LPT. Both types are investigated in this thesis work. The main contributions of this thesis work are presented in 6 chapters, with each based on an individual scientific paper. Paper 1 presents the rationale behind the …
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Preparation and investigation of polymer-foam films and polymer-layer systems for ferroelectrets
… PP-foam ferroelectrets may exhibit piezoelectric d33 coefficients of 600 pC/N and more. Their operating temperature can, however, not be much higher than 60 °C. Recently developed polyethylene-terephthalate (PET) and cyclo-olefin copolymer (COC) foam ferroelectrets show slightly better d33 thermal …
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Fabrication and Properties of Bi1/2Na1/2TiO3 Based Ferroelectric Ceramics with Low Levels of B-site Additives
… Improvements of approximately 30% in the d33 values were found at concentrations of 0.5% of each of the additives, but higher concentrations of the additives degraded the d33 values. The coercive field was affected by the additions to BNT. Increasing concentrations of BNMN reduced the …
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High temperature ultrasonic gas flow sensor based on lead free piezoelectric material
… found to increase the piezoelectric coefficient (d33) from around 5 pC N¯¹ in pure bismuth titanate, to above 20 pC N¯¹ in doped compounds. This increase is attributed to lower conductivity and improved poling conditions. Further increases in d33 (up to 35 pC N¯¹) were then realised through …
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High-strain actuation of lead-free perovskites : compositional effects, phenomenology and mechanism
… mapped. The peak of electromechanical response (d33 = 400 pC/N) has been found at the composition (Bil/2Nal/2)0.93Bao.07Zro.02Tio.9803. The compositional dependence of ferroelectric phase stability has been mapped by means of a Landau type free energy expansion. A nanodomain relaxation mechanism …
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Processing Effects for Integrated PZT: Residual Stress, Thickness, and Dielectric Properties
… 30MPa tensile stress resulted in an increase of d33 from 33 to 65pm/V, irrespective of changes in film thickness. These results isolated, for the first time, the effects of stress and thickness on the dielectric, ferroelectric and piezoelectric properties of PZT films without convolution from the …
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Piezoreflectance of gallium arsenide
… potential ratios, D1/5 /Dl/l = -.55 ± .03, D35/D33 = .77 ± .03, have been derived. Comparison of the hydrostatic component of the perturbation with the energy derivative of the unmodulated reflectivity spectrum shows good agreement with a rigid shift model. Finally, the 4.5 eV transition has …
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Piezoelectric single crystal based one-dimensional phased array for breast tissue imaging
… due to its superior piezoelectric properties (d33 = 2,800 pC/N, εr = 7,000, k33 = 0.93). I then fabricated a 1D phased array transducer consisting of 64 elements with an operational frequency of 7.0 MHz. The 1D array exhibits promising acoustic performance with i) a maximum imaging depth of 80 …
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Self-Assembled Barium Titanate Nanoscale Films by Molecular Beam Epitaxy
… coefficients. An enhancement in the d33 for the 5 nm thin films compared to the 40 nm thin films was also observed. The compressive strain on 5 nm thin films enhanced the polarization over fully relaxed 40 nm thin films. </p>
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Magnetoelectric Oxide Nanocomposite Heterostructures
… interface and a larger piezoelectric coefficient d33 was achieved in this film. Finally, with respect to their characteristics and potential, I redirected from two-dimensional thin film materials to one-dimensional nanowire materials. By utilizing vertically aligned templates, I fabricated a new …
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Magnetoelectric Effect in Ferroelectric-Ferromagnetic Heterostructures
… materials shared a linear relationship (d31 or d33) with the electric field, which is true only with small electric field signals. In contrast, the largest strain is produced during phase transformation in piezoelectric single crystals. In this work, we systematically investigated electric field …
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Effect of Dopants on the Local Atomic Structure and Sintering Behavior of Bismuth Sodium Titanate
… temperature and the piezoelectric coefficient d33 decreased with increasing cobalt concentrations. The dielectric properties deteriorated as well. This was attributed to the high electrical conductivity of the doped samples, which prevented full poling.
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Macro-Fiber Composites for Sensing, Actuation and Power Generation
… electrodes that capitalize on the higher d33 piezoelectric coupling coefficient that allow it to produce higher forces and strain than typical monolithic piezoceramic materials. The research presented in this thesis investigates some potential applications for the MFC as well as topics in …
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Synthesis-Structure-Property Relationships in Lead-Free Piezoelectric Materials
… The longitudinal piezoelectric constant (d33) of samples sintered for 20h at 1175°C, 1200°C and 1225°C was measured to be ~153 pC/N, ~216 pC/N and ~180 pC/N, respectively. Next, a novel method was developed for the synthesis of nanostructured lead-free ferroelectric NBT-BT whiskers with …