Nanoscale Dipole Engineering of BaTiO3 Using Dy3+-Ta5+ and Ho3+-Ta5+ Dipole Pairs
Date
2023-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
New York State College of Ceramics at Alfred University. Inamori School of Engineering.
Abstract
Barium titanate (BaTiO3) is the most widely used base material for electroceramic capacitor technology. Previously, experiments conducted within the New York State College of Ceramics (NYSCC) Laboratory for Electroceramics (LEC) at Alfred University have demonstrated that substituting dipole pairs for the titanium ion in the center of the octahedral cage in BaTiO3 can enhance the electrical properties of the material for storing charge and provide the enhanced properties over a larger operating temperature range as compared with pure BaTiO3. This thesis investigates the properties of BaTiO3 - based material processed using dipole engineering at the nanoscale, through substitution of Dy3+-Ta5+ and Ho3+-Ta3+ dipoles for Ti4+, to form Ba(Dy,Ta)xTi1-2xO3 and Ba(Ho,Ta)xTi1-2xO3, respectively. The dipole pairs maintain charge neutrality, but desirably possess higher polarizability values than the original Ti4+ ion; thereby, leading to enhancements in electrical properties. The substitutions were performed through a solid-state reaction following the stoichiometric equation: Ba(Ḇ3+, Ta5+)xTi1-2xO3, with x = 0.0000, 0.0025, 0.0050, 0.0100, 0.0250 and 0.0500, and Ḇ being the Dy3+ or Ho3+. The material properties were investigated using room temperature and energy dependent characterization tools to improve understanding of the effects of dipole pair substitutions, including concentration dependence. Material characterization has been completed using: room temperature x-ray diffraction to determine room temperature structure, phase purity and lattice parameter; temperature dependent resistivity to determine intrinsic material resistivity and activation energy; impedance - inductance - resistance (LCR) to determine temperature and frequency dependent relative permitivity; temperature dependent Raman to determine thermally induced structural phase transitions; and, scanning electron microscope to determine microstructure, and grain size. Analysis indicates that a range of a priori predicted properties, using the new simple material model (NSMM) as well as projections from prior results, occur. Further, novel Raman properties are also observed, including a BaTiO3 - like lattice and a second lattice associated with either the individual ions Dy3+ and Ho3+ or the Dy - Ta and Ho - Ta dipole pairs within Ba(Dy,Ta)xTi1-2xO3 and Ba(Ho,Ta)xTi1-2xO3, respectively. Importantly, a decoupling of the relative permitivity peak from the structural phase transition temperature is demonstrated.
Description
Thesis completed in partial fulfillment of the requirements for the degree of Master of Science in Ceramic Engineering at the Inamori School of Engineering, New York State College of Ceramics at Alfred University
Type
Thesis
item.page.format
Keywords
Electroceramics, Electronic ceramics