Synthesis and characterization of BaTiO3 pellets and thin films
Barium titanate was synthesized using a solid state approach and an aqueous method. Solid state syntheses were used to prepare barium titanate pellets using a powder metallurgy method. Appropriate amounts of barium carbonate and titanium dioxide powder were mixed together in an agate mortar. Bari...
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| Format: | Thesis |
| Language: | English |
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| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/42988/1/P.1-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/42988/2/Full%20Text.pdf |
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| Summary: | Barium titanate was synthesized using a solid state approach and an aqueous method.
Solid state syntheses were used to prepare barium titanate pellets using a powder
metallurgy method. Appropriate amounts of barium carbonate and titanium dioxide
powder were mixed together in an agate mortar. Barium titanate pellets were mixed
according to 5 different ratios of Ba/Ti which are 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1.1.
Pellets were sintered in air at a temperature 1400 °C. Barium titanate thin films were
prepared using an aqueous method. Sol-gel of barium titanate was prepared according to
the similar ratios as pellets. Thin films of barium titanate sol-gel were deposited using a
desktop printer onto a glass substrate and fired at 400 °C. Both pellets and thin films
were characterized by X-ray diffraction, scanning electron microscope, Atomic Force
Microscope (thin films only), and impedance spectroscopy. This thesis focuses on
determination of dielectric properties of barium titanate including the resistance,
capacitance, dielectric constant, relaxation frequency, and loss tangent. The highest
density for the barium titanate pellets were 5.90 g/cm3 when a Ba:Ti ratio of 1:1 was
used. The average thicknesses of the thin films were 2.89 nm as measured using the
atomic force microscope and verified using the scanning electron microscope.
Characteristic of barium titanate were observed under various temperatures starting
from room temperature up to 450 °C (for pellets) and 300 °C (for thin films). The
measured dielectric constant of the pellets at 10 kHz (at room temperature) varied from
a maximum of 2810 to a minimum of 1375. Samples with Ba:Ti ratio of 1:1 show the
highest dielectric properties. The highest dielectric constant was measured at 100 °C for
stoichiometric samples. X-ray diffraction result shows the production of a secondary
phase, Ba2TiO4 when barium excess of 5 % or 10 % was added. The barium titanate
thin films showed lower crystallinity than the pellets. X-ray diffraction peak broadening
measurements of the thin films show an average crystallite size of 14 nm compared to
110 nm for the pellets. Impedance spectroscopy of the barium titanate pellets show the
presence of a resistive grain boundary component, a conductive bulk component as well
as a ferroelectric third component. The presence of these components were verified via
Curie Weiss plots where applicable. The barium titanate thin films did not show the
presence of the ferroelectric component. The dielectric constant of the pellets (ɛ= 2810)
were significantly higher than the dielectric constant of the thin films (ɛ = 342) and this
was attributed to the lower crystallinity of the thin films. |
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