Structure and densification of thin films prepared from soluble precursor powders by sol gel processing [Elektronische Ressource] / vorgelegt von Matthias Bockmeyer

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Informations

• Publié par: julius-maximilians-universitat_wurzburg
• Publié le: 01 janvier 2007
• Nombre de lectures: 35
• Langue: Deutsch
• Poids de l'ouvrage: 27 Mo

Extrait

STRUCTURE AND DENSIFICATION OF THIN FILMS PREPARED
FROM SOLUBLE PRECURSOR POWDERS
BY SOL-GEL PROCESSING




Dissertation
zur Erlangung des naturwissenschaftlichen Doktorgrades
der Julius-Maximilians-Universität Würzburg




vorgelegt von
Matthias Bockmeyer
aus Würzburg


Würzburg 2007













Eingereicht am:……………………………...
Bei der Fakultät für Chemie und Pharmazie
1. Gutachter: ………………………….
2. Gutachte…….
der Dissertation.

1. Prüfer: ………………………………
2. ……
3. Prüfer: ………………………………
des öffentlichen Promotionskolloquiums.

Tag des öffentlichen Promotionskolloquiums:……………………
Doktorurkunde ausgehändigt am:………………………………...

































“I am still confused,
but on a higher level”
Enrico Fermi
TABLE OF CONTENTS IV

1 INTRODUCTION ...........................................................................................................1
2 STATE OF KNOWLEDGE ................................................................................................2
2.1 SOL-GEL PROCESSING......................................................................................................... 2
2.2 THIN FILM FORMATION....................................................................................................... 3
2.3 FILM DENSIFICATION .......................................................................................................... 4
2.4 STRESS FORMATION IN THIN FILMS....................................................................................... 5
2.5 CRACK FORMATION IN THIN FILMS 7
2.6 TITANIA ........................................................................................................................... 9
3 OBJECTIVES OF THESIS ...............................................................................................10
4 EXPERIMENTAL .........................................................................................................11
4.1 MATERIALS ....................................................................................................................11
4.2 PREPARATION .................................................................................................................11
4.2.1 PRECURSOR POWDER PREPARATION................................................................................11
4.2.2 SOL PREPARATION......................................................................................................12
4.2.3 PREPARATION OF SOL POWDER AND FILM POWDER ............................................................12
4.2.3 THIN FILM PREPARATION ..............................................................................................12
4.3 CHARACTERIZATION13
4.3.1 ANALYTICAL ULTRACENTRIFUGATION .............................................................................13
4.3.2 CHEMICAL ANALYSIS ..................................................................................................13
4.3.3 DEFECT ANALYSIS13
4.3.4 ELLIPSOMETRIC POROSIMETRY.......................................................................................13
4.3.5 FILM THICKNESS AND REFRACTIVE INDEX .........................................................................14
4.3.6 INFRARED SPECTROMETRY............................................................................................14
4.3.7 MICROSCOPY ...........................................................................................................14
4.3.8 NITROGEN SORPTION14
4.3.9 PENCIL HARDNESS TEST ...............................................................................................15
4.3.10 PHOTOCATALYTIC ACTIVITY .........................................................................................15
4.3.11 3-POINT BENDING TEST15
4.3.12 REFRACTIVE INDEX OF POWDERS....................................................................................15
4.3.13 SKELETAL DENSITY......................................................................................................15
4.3.14 STRESS MEASUREMENTS ..............................................................................................15
4.3.15 THERMO ANALYSIS.....................................................................................................16
4.3.16 VISCOSITY................................................................................................................16
4.3.17 X-RAY – DIFFRACTOMETRY ..........................................................................................16
4.3.18 X-RAY – REFLEKTOMETRY ............................................................................................16
TABLE OF CONTENTS V
5 RESULTS AND DISCUSSION..........................................................................................18
5.1 SOLUBLE PRECURSOR POWDERS.........................................................................................18
5.2 ETHANOL BASED COATING SYSTEMS ..................................................................................22
5.2.1 SOLUBILITY AND STABILITY ...........................................................................................22
5.2.2 CHANGES INDUCED BY THE SOLVENT COMPOSITION ..........................................................24
5.2.3 DENSIFICATION OF ETHANOL BASED FILM POWDERS ...........................................................30
5.2.3.1 GENERAL CONSEQUENCE OF LARGE SURFACE-TO-VOLUME RATIO AND AIR MOISTURE DURING
FILM FORMATION ...................................................................................................30
5.2.3.2 CHANGES INDUCED BY 1,5-PENTANEDIOL...................................................................36
5.2.4 MICROSTRUCTURE OF THIN FILMS ..................................................................................41
5.2.4.1 CONSTRAINT OF SHRINKAGE BY THE SUBSTRATE: GENERAL CONSEQUENCE..........................41
5.2.4.2 CHANGES INDUCED BY THE SOLVENT COMPOSITION.......................................................46
5.2.5 RESIDUAL STRESS AND CRACKING OF THIN FILMS...............................................................55
5.2.5.1 INFLUENCE OF SOLVENT COMPOSITION ON RESIDUAL STRESS OF THIN FILMS .........................55
5.2.5.2 CHARACTERIZATION AND ANALYSIS OF CRACKING IN THIN FILMS ......................................57
5.2.5.3 INFLUENCE OF SOLVENT COMPOSITION ON CRACKING OF THIN FILMS .................................60
5.2.5.4 INFLUENCE OF AIR MOISTURE DURING COATING PROCEDURE ............................................62
5.3 WATER BASED COATING SYSTEMS .....................................................................................66
5.3.1 SOLUBILITY AND STABILITY ...........................................................................................66
5.3.2 GENERAL CONSEQUENCE OF WATER AS SOLVENT ..............................................................69
5.3.3 CHANGES INDUCED BY THE SOLVENT COMPOSITION ..........................................................74
5.3.4 DENSIFICATION OF WATER BASED FILM POWDERS78
5.3.4.1 GENERAL CONSEQUENCE OF LARGE SURFACE-TO-VOLUME RATIO AND AIR MOISTURE DURING
FILM FORMATION ...................................................................................................78
5.3.4.2 CHANGES INDUCED BY 1,5-PENTANEDIOL IN THE SOLVENT..............................................80
5.3.5 MICROSTRUCTURE AND CRACKING OF THIN FILMS.............................................................82
5.4 TRIETHANOLAMINE BASED PRECURSOR POWDERS ................................................................88
5.4.1 CHARACTERIZATION OF POWDERS ISOLATED FROM COATING SOLUTIONS................................88
5.4.2 DENSIFICATION OF THIN FILMS.......................................................................................92
5.5 VALIDITY FOR OTHER SOL-GEL SYSTEMS (8YSZ)..................................................................98
5.6 FURTHER CONSEQUENCES OF THIN FILM DENSIFICATION......................................................102
6 SUMMARY..............................................................................................................104
7 ZUSAMMENFASSUNG...............................................................................................106
8 LITERATURE ............................................................................................................109
1 I NTRODUCTION 1
1 INTRODUCTION
Besides mostly vacuum-based technologies such as physical or chemical vapor deposition (PVD,
CVD) inorganic thin films can be prepared by sol-gel processing [BRI90]. Thin films can be
fabricated on large areas with high quality from liquid precursors [GOM98,GOM00,TAK06]. From
a commercial point of view this coating technology is especially advantageous even for small- and
mid- sized companies, because only low investment and operating costs are required compared
to vacuum-based technologies [LOE03b].
Most technologic