Paired zinc tungsten dipole engineering of barium titanate at the nanoscale
Date
2021-05-11
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Abstract
Barium titanate, BaTiO3, is a widely used capacitor material with well-defined structural transition temperatures, marking changes in material dielectric behavior. Above the Curie temperature, Tc, the structure does not have a permanent dipole moment, limiting the operable temperature for spontaneous polarization. Increasing the energy in the crystal lattice enables engineering of the phase transition temperatures, from the Clausius-Mossotti relation. Controlling the phase transitions has been successful in past research, proving advantageous for electrical and dielectric property changes. The additional energy in the form of discrete and localized electric fields could be provided by substituted dipole pairs. In this work, utilizing Zn2+-W6+ as the dipole pair, compositions of Ba(Zn2+,W6+)xTi1-2xO3 with x equal to 1, 0.025, 0.01375, 0.0025, 0.001375, 0.00025, and 0. Sample materials are synthesized from high purity solid oxide precursor materials based on the solid-state ceramic sintering process technique. Scanning electron microscopy (SEM), room temperature X-ray diffraction (XRD), UV-VIS-IR spectroscopy, electric resistivity and dielectric permittivity measurements were taken to test and analyze the material behavior from the dipole substitution. From the experimental analysis, Zn-W dipole substituted BaTiO3 experiences phase and structural changes at high dipole concentrations, increased the resistivity at all dipole concentrations, and increased the dielectric behavior for the higher dipole concentrations as well.
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Thesis completed in partial fulfillment of the requirements for the Alfred University Honors Program.
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Thesis
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Keywords
Honors thesis, Barium titanate, Dipoles, Engineering