Thesis (Ph. D.)--University of Rochester. Dept. of Chemical Engineering, 2014.
Hydroxyapatite (Ca5(PO4)3OH) is a highly studied material because of its similar
composition to bone and its ionic conducting capabilities. This thesis investigates a novel
electrochemical-hydrothermal synthesis method for depositing a hydroxyapatite membrane on
metal substrates. The deposited membrane is highly crystalline, oriented along the
crystallographic c-axis, which is perpendicular to the substrate, and is a uniform array of single
crystals. The novel synthesis method was modified by adding the dopants yttrium, ytterbium,
and fluoride during the hydrothermal synthesis. The thermal stability of the films was
characterized using scanning electron microscopy and X-ray diffraction. It was shown that
fluoride helped reduce dehydroxylation of the membrane at elevated temperatures. The stored
charge of yttrium-fluoride co-doped membranes was measured using the thermally stimulated
depolarization current test. The samples were shown to have extremely high stored charge
values even without electrical polarization. Ytterbium doped membranes were characterized
using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction.
Conductivity tests were also performed using electrochemical impedance spectroscopy, as well
as fuel cell performance tests. Finally, a new method of electrochemically depositing silver
nanoparticles onto hydroxyapatite films was developed and characterized in order to make an
antimicrobial coating. Preliminary experiments with Staphylococcus aureus demonstrated the
silver coated sample’s ability to retard bacteria growth.
