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Preparation of the Bi12SiO20 thin films by the sol-gel method
Š. Kunej, A. Veber and D. Suvorov
Advanced MaterialsJožef Stefan Institute
Outline
• Introduction• Aim of work• Experimental• Results
• Sapphire
• Si/SiO2/TiO2/Pt
• Spinel MgAl2O4
• Conclusions
Introduction
SILLENITESILLENITE
MINITURIZATION
THIN FILMSTHIN FILMS
* M. Valant, D. Suvorov; J. Am. Ceram. Soc., 84[12], 2900-904, 2001
AgAg
“Bulk” Bi Bi1212SiOSiO2020*
(5.5GHz):
’ = 37.6
Qxf = 8100 GHz
f = -20 ppm/K
Tsint. = 850°C
Microwave technology
(LTCC)
Aim of work
• Preparing Bi12SiO20 (BSO) thin films using sol-gel method
• Determining microstructure and thickness of BSO thin films deposited on substrates:– Sapphire
– Si/SiO2/TiO2/Pt
– Spinel MgAl2O4
Experimental: SOL-GEL Synthesis
Used chemicals:Used chemicals:•Bismuth (III) nitrate
[Bi(NO3)3·5H2O]•Tetraethly orthosilicate
(TEOS) [Si(OC2H5)5]•Acetic acid
[CH3COOH]•Ethanolamine
[H2NCH2CH2OH]•2-ethoxyethanol
[C2H5OCH2CH2OH]
Vacuum drying
60°C/96h
Bi(NOBi(NO33
))
Acetic acid+
Ethanolamine
Bismuth Bismuth complex complex solutionsolution
SolSol
Bi(NOBi(NO33))33·5H·5H22
OO
Spin-Spin-coating coating (5000 rpm)
Firing:
300-700°C/1h
TEOSTEOS +2-
ethoxyethanol
Analytical methods:Analytical methods:
XRD XRD SEM SEM AFM AFMPyrolysis: 220°C/2min
4x4x
Results
C / ( mol/l ) t / h
1.20 5
1.12 48
0.98 168
0.76 456
0.67 -
050
100150200250300350400450500
0,5 0,6 0,7 0,8 0,9 1 1,1 1,2 1,3
c ( mol/L )
time o
f gela
tion (
h )
Influence of solvent on gelation time :
Results: SapphireResults: Sapphire
Spin-coating: 4 x 5000 rpm
Firing: 700°C/1h
Results: Sapphire
d 400nm
Results: Si/SiO2/TiO2/Pt
Spin-coating: 4 x 5000 rpm
Firing: 700°C/1h
Results: Si/SiO2/TiO2/Pt
d 230nm
Results: Spinel
Spin-coating: 4 x 5000 rpm
Firing: 700°C/1h
Results: Spinel
d 300nm
Conclusions• The Bi12SiO20 (BSO) thin films were successfully
prepared by the sol-gel method• The BSO thin film obtained on sapphire substrate is
porous with rough surface• Homogeneous BSO thin film of thickness 230nm was
obtained for the thin film deposited on Si/SiO2/TiO2/Pt substrate
• Thin film deposited on the spinel substrate shows homogeneous microstructure with grain size of 200-500nm.
Future work:• Optimization of BSO sol-gel precursor• Obtaining “denser” BSO thin films • Dielectric measurements of BSO thin films