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HIGH STRAIN FUNCTIONALLY GRADED BARIUM TITANATE AND ITS MATHEMATICAL CHARACTERIZATION

SURANA, RAJESH R
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1096650232

Abstract Details

2004, MS, University of Cincinnati, Engineering : Materials Science.
Ferroelectric materials are used in variety of sensor and actuator applications. These are generally piezoelectric or electrostrictive, polycrystalline ceramics. The behavior of conventional materials is characterized by good high frequency response and low hysteresis, though the strains are limited to 0.1 %. A variety of methods have been developed for creating large displacement actuators by using monomorph or bimorph benders, RAINBOW, single crystals, relaxor based systems such as PMN-PT, formulated near the morphotropic phase boundary etc. In unimorphs and bimorphs; the bonding interface has low strength. Also large stress discontinuity and concentration are induced in the bonding interface due to the difference of material properties between the shim and piezoelectric material. The stress concentration and structural weakness at the bonding interface are the main causes for the breakdown of the bimorph and unimorph actuators in cyclic actuation. To increase the durability of bending actuators, RAINBOW actuators were proposed. In the RAINBOW, since the reduced layer and piezoelectric layer are chemically integrated, the interface has high strength, but the stress discontinuity cannot be relieved due to the discontinuity of material properties. In this study more structurally efficient functionally graded barium titanate was investigated. It was found that strain was a function of dielectric constant and spontaneous polarization change; on application of electric field. High dielectric constant was obtained by doping with Nd2O3 and ZrO2, which resulted in core-shell grain microstructure. In addition both grain boundary and surface barrier structure were used to increase the dielectric constant to the order of 20,000 to 35,000. Due to difference in expansion coefficient of different layers, functionally graded BaTiO3 is pre-stressed and has dome shape. This anisotropic macroscopic stress leads to preferred domain orientation (hence high spontaneous polarization) which when switched by electric field leads to high strain; upto 1.7 %. In this study the analytical equation was derived to correlate the observations and predict the strain behavior. For dome shaped functionally graded BaTiO3 the effective piezoelectric coefficient, d31 calculated was 196 X 10-11 C/N and spontaneous polarization change was 0.198 C/m2. This leads high strain behavior of functionally graded barium titanate.
Dr. Relva Buchanan (Advisor)
105 p.
Engineering, Materials Science
doped barium titanate; functionally graded structures; mathematical modeling of strain; barrier layer capacitors; actuators.

Recommended Citations

Citations

  • SURANA, R. R. (2004). HIGH STRAIN FUNCTIONALLY GRADED BARIUM TITANATE AND ITS MATHEMATICAL CHARACTERIZATION [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1096650232

    APA Style (7th edition)

  • SURANA, RAJESH. HIGH STRAIN FUNCTIONALLY GRADED BARIUM TITANATE AND ITS MATHEMATICAL CHARACTERIZATION. 2004. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1096650232.

    MLA Style (8th edition)

  • SURANA, RAJESH. "HIGH STRAIN FUNCTIONALLY GRADED BARIUM TITANATE AND ITS MATHEMATICAL CHARACTERIZATION." Master's thesis, University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1096650232

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Cincinnati and OhioLINK.