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AQUEOUS SYNTHESIS AND DEPOSITION TECHNIQUES FOR THE LEAD FREE
PIEZOELECTRIC, SODIUM POTASSIUM NIOBATE-Matthew Clark-
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PIEZOELECTRICITY
• Material that in response to a mechanical stress creates a voltage and vis versa
• Due to symmetry, a ferroelectric must also be a pyro and a piezoelectric
• Extensively used in microelectronic applications
Piezoelectric
Pyroelectric
Ferroelectric
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CURRENT MATERIALS
Lead Zirconium Titanate (PZT), Pb(Zr1−xTix)O3
The EU has banned the use of lead in electronic devices since 2006
Difficult to make quality thin films
Electrical Current
PbO
Zr/Ti
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WHAT IS SODIUM POTASSIUM NIOBATE
Commonly referred to as KNN
K0.5Na0.5NbO3
A lead free ferroelectric material which in certain applications is expected to match or surpass PZT
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AQUEOUS DEPOSITION
Processing is done under atmospheric conditions
Important for the creation of thin films using low energy methods
(Na,K)6Nb6O19 solution is spun onto substrate material
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Al2O3 Substrate SrTiO3 Substrate
Quartz Substrate
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X-RAY DIFFRACTION DATA
2θ
Inte
nsity
Al2O3 Substrate
Phase Pure KNN: 8-layer film
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ELLIPSOMETRY DATA
Ellipsometry is a optical technique that can give information concerning thickness and optical constants
35.21 +/- 0.048 nm in thickness with an MSE of 5.213
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ATOMIC FORCE MICROSCOPY (AFM)
A high tech turntable needle
The AFM tip is dragged across the surface and resulting data gives an accurate image of the surface morphology of the film
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Polycrystalline surface morphology with few voids
Average roughness of 4.82 nm (amplitude)
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EPITAXIAL THIN FILMS
Epitaxial thin films consist of ordered crystallite domains matching the structure of the underlying substrate
Causes an increase in physical properties
SubstrateFilm
Polycrystalline Film
Epitaxial Film
SubstrateFilm
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X-RAY DIFFRACTION DATA
Epitaxial KNN
Inte
nsity
2θ
1-layer film on SrTiO3
Bare SrTiO3 Substrate
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FUTURE WORK
Perform electrical characterization to determine d33 and other figures of merit
Reduce surface roughness of films through addition of polymers
Improve piezoelectric properties through doping of material
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ACKNOWLEDGEMENTS
Research possible due to funding from URISC, Oregon State Department of Chemistry, The Center for Sustainable Materials Chemistry and The National Science Foundation.
Thank you, Michelle Dolgos and Dylan Fast. Without your guidance, this work would not have been realized.
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KNN FROM POLYOXOMETALATES
The goal is to create KNN thin films using these metal clusters
stoichiometric ratios of the two alkali-niobium clusters: K8Nb6O19 and HNa7Nb6O19 are mixed in solutionHexaniobate clusters