M A T E R I A L S R E S E A R C H S O C I E T Y SYMPOSIUM P R O C E E D I N G S V O L U M E 271

Better Ceramics Through Chemistry V Symposium held April 27-May 1, 1992, San Francisco, California, U.S.A.

EDITORS:

Mark J . Hampden-Smith University of New Mexico

Albuquerque, New Mexico, U.S.A.

Walter G. Klemperer University of Illinois

Urbana, Illinois, U.S.A.

C. Jeffrey Brinker Sandia National Laboratories

Albuquerque, New Mexico, U.S.A.

M A T E R I A L S R E S E A R C H S O C I E T Y Pittsburgh, Pennsylvania

Contents

P R E F A C E xv

MATERIALS R E S E A R C H S O C I E T Y SYMPOSIUM PROCEEDINGS xvi

P A R T I : M O L E C U L A R R O U T E S T O C E R A M I C M A T E R I A L S

*NEW C H E M I S T R Y FOR T H E S O L - G E L PROCESS: A C E T O N E AS A NEW CONDENSATION R E A G E N T 3

Subhash C . Goel, Michael Y . Chiang, Patrick C . Gibbons, and William E . Buhro

* H E T E R O M E T A L L I C AGGREGATES AS INTERMEDIATES ON T H E M O L E C U L A R ROUTES TO MULTICOMPONENT OXIDES 15

Liliane G. Hubert-Pfalzgraf

F U R T H E R STUDIES ON ALUMINUM OXOALKOXIDE C L U S T E R S 27 R.A. Sinclair, M . L . Brostrom, W.B. Gleason, and R.A. Newmark

STUDIES ON T H E FORMATION OF TIN(IV) O X Y G E N COMPOUNDS B Y SOL-GEL-PROCESS 33

H. Reuter, Μ. Kremser, D. Schröder, and Μ. Jansen

HYDROLYSIS-CONDENSATION OF A L K Y L T I N - T R I A L K O X I D E S 45 Frangois Ribot, F . Banse, and C. Sanchez

HYDROLYSIS AND CONDENSATION OF MODIFIED TIN(IV) A L K O X I D E COMPOUNDS TO FORM C O N T R O L L E D POROSITY MATERIALS 51

Christophe Roger, M.J. Hampden-Smith, and C .J . Brinker

P O L Y N U C L E A R TITANIUM OXOALKOXIDES: M O L E C U L A R BUILDING B L O C K S FOR NEW MATERIALS? 57

Y.W. Chen, W.G. Klemperer, and C.W. Park

RAMAN AND S U R F A C E ENHANCED RAMAN SPECTROSCOPY O F TITANIUM C A R B O X Y L A T E S 65

Beatrice A. Van Vlierberge-Torgerson, Dilum Dunuwila, and Kris A. Berglund

HYDROLYSIS O F ZIRCONIUM PROPOXIDE B Y AN ESTERIFICATION REACTION 71

I. Laaziz, A. Larbot, C . Guizard, A. Julbe, and L . Cot

M O L E C U L A R DESIGN OF C A R B O X Y L I C PRECURSORS FOR ZIRCONIA 77 Allen W. Apblett, Jin Lei, and Galina D. Georgeva

PROPERTIES O F Z r 0 2 G E L S PREPARED B Y CONTROLLED C H E M I C A L MODIFICATION METHOD OF A L K O X I D E 83

Hisao Suzuki, Hajime Saito, and Hiroaki Hayashi

SINGLE-COMPONENT ROUTES TO PEROVSKITE PHASE MIXED M E T A L OXIDES 89

Clive D. Chandler, M.J. Hampden-Smith, and C .J . Brinker

SYNTHESIS OF BARIUM TITANATE B Y A BASIC pH PECHINI PROCESS 95 Suresh Kumar and Gary L . Messing

*Invited Paper

ν

PREPARATION O F STRONTIUM TITANATE POWDERS B Y DECOMPOSITION OF P O L Y M E R I C PRECURSORS 101

S .L . Peschke, M. Ciftcioglu, D.H. Doughty, and J.A. Voigt

SYNTHESIS, S T R U C T U R E , AND CHARACTERIZATION OF L a ^ B a T i O , (0 < X < 1) 107

Joseph E . Sunstrom IV and Susan M. Kauzlarich

COMBUSTION SYNTHESIS OF Sr-SUBSTITUTE L a C o 0 4 F e 0 6 O 3 POWDERS 113

J.J . Kingsley, L . A . Chick, G.W. Coffey, D . E . McCready, and L . R . Pederson

SYNTHESIS O F F E R R O E L E C T R I C PEROVSKITES THROUGH AQUEOUS SOLUTIONS TECHNIQUES 121

G. Guzmän-Martel, Μ.A. Aegerter, and P. Barboux

NEW GROUP 2 COMPOUNDS U S E F U L FOR PREPARATION O F THIN FILMS OF E L E C T R O N I C CERAMICS 127

William S. Rees, Jr. , Kerstin A. Dippel, Michael W. Cards, Celia R. Caballero, Debra A. Moreno, and Werner Hesse

STABILIZATION OF M E T A L ALKOXIDES (Μ = Ba, Cu) B Y ALKANOLAMINES 135

L . G . Hubert-Pfalzgraf, M.C. Massiani, J . C . Daran, and J. Vaissermann

SOLID S T A T E S T R U C T U R E S , DECOMPOSITION PATHWAYS, AND VAPOR PHASE BY-PRODUCTS OF Y(acac) 3 T Y P E OMVPE PRECURSORS FOR THIN FILMS OF YTTRIUM-CONTAINING C E R A M I C M A T E R I A L S 141

William S. Rees, Jr. , Henry A. Luten, Michael W. Cards, Eric J . Doskocil, and Virgil L . Goedken

AGGREGATION AND HYDROLYSIS REACTIONS OF BISMUTH A L K O X I D E S 149

Kenton H. Whitmire, Carolyn M. Jones, Michael D. Burkart, J . Chris Hutchison, and Andrew L . McKnight

S O L - G E L SYNTHESIS O F YBiuC^O- , , USING Y T T R I U M , BARIUM, AND COPPER P O L Y E T H E R A L K O X I D E PRECURSORS 155

Catherine J . Page, Carol S. Houk, and Gary A. Burgoine

PREPARATION O F BSCCO PRECURSORS BY WATER EXTRACTION VARIANT O F S O L - G E L PROCESS 161

A. Deptula, W. Lada, Τ. Olczak, and A. Di Bartolomeo

FROM CERAMICS TO SUPERCONDUCTORS: RAPID MATERIALS SYNTHESIS B Y SOLID-STATE METATHESIS REACTIONS 169

Randolph E . Treece, Edward G. Gillan, Richard M. Jacubinas, John B. Wiley, and Richard B. Kaner

CHARACTERIZATIONS OF S O L - G E L CORDIERITE PRECURSORS 175 Yun Fa Chen, Said E l Hadigui, and Serge Vilminot

S O L - G E L PROCESS FROM H E T E R O B I M E T A L L I C ALKOXIDES TO INCORPORATE LANTHANIDES IN AN ALUMINA MATRIX 181

Chaitanya K. Narula

SYNTHESIS O F NEW COMPOUNDS B Y ION-EXCHANGE REACTIONS 187 M . E . Villafuerte-Castrejon, and A. Aragon-Pina

vi

COMPARATIVE STUDY OF T H E S O L - G E L AND METALLO-ORGANIC DECOMPOSITION (MOD) PROCESSES FOR T H E PREPARATION O F INORGANIC MATERIALS 193

Gustavo R. Paz-Pujalt, W. Nie, and C. Lurin

P A R T I I : P A R T I C U L A T E AND P O L Y M E R I C S O L S

*COMPLEXATION O F Zr(IV) PRECURSORS IN AQUEOUS SOLUTIONS 201 J . Livage, M. Chatry, M. Henry, and F . Taulelle

F R A C T A L GROWTH DURING GELATION 213 Edward J.A. Pope

SOLVENT QUALITY E F F E C T S IN S O L - G E L PROCESSING 219 Joseph K. Bailey

A RAMAN SPECTROSCOPIC STUDY OF THE INITIAL STAGES O F HYDROLYSIS O F T E T R A E T H O X Y S I L A N E 225

J.D. Barrie and K . A . Aitchison

SILICON-29 NMR STUDY ON T H E INITIAL STAGE OF T H E CO-HYDROLYSIS O F T E T R A E T H O X Y S I L A N E AND M E T H Y L T R I E T H O X Y -SILANE 231

Yoshiyuki Sugahara, Yoichi Tanaka, Shuji Sato, Kazuyuki Kuroda, and Chuzo Kato

S T R U C T U R A L CHARACTERIZATION OF G E L S PREPARED FROM CO-HYDROLYSIS O F T E T R A E T H O X Y S I L A N E AND D I M E T H Y L D I E T H O X Y -SILANE 237

Florence Babonneau, Laurence Bois, and Jacques Livage

E L E C T R O N E G A T I V I T Y - B A S E D COMPUTATION OF 2 9 S i C H E M I C A L SHIFTS 243

M. Henry, C . Gerardin, and F . Taulelle

RAMAN AND INFRARED STUDY OF M E T A L ALKOXIDES DURING SOL-G E L PROCESS 249

O. Poncelet, J -C . Robert, and J . Guilment

R E A C T I O N KINETICS FOR T H E HYDROLYSIS OF TITANIUM ISOPROPOXIDE C A R B O X Y L A T E COMPLEXES 257

Charles D. Gagliardi, Dilum Dunuwila, Beatrice A. Van Vlierberge-Torgerson, and Kris A. Berglund

USAXS AND X - R A Y MICROSCOPY INVESTIGATIONS ON SILICA AND PRECURSORS O F Z E O L I T E S 263

Theo P.M. Beelen, Wim Η. Dokter, Harold F . van Garderen, Rutger A. van Santen, Mike T. Browne, and Graeme R. Morrison

R H E O L O G Y OF ZIRCONIA-ALUMINA GELCASTING SLURRIES 269 Α. Bleier, O.O. Omatete, and C G . Westmoreland

PRODUCTION O F SPHERICAL POWDERS OF INORGANIC COMPOUNDS B Y WATER EXTRACTION VARIANT OF S O L - G E L PROCESS 277

A. Deptula, J . Rebandel, W. Drozda, W. Lada, and T. Olczak

N O V E L PRECIPITATION ROUTE TO SILICA GRAIN 285 Barbara Simms and Tom Gallo

* Invited Paper

vii

T H E O R E T I C A L AND E X P E R I M E N T A L INVESTIGATIONS OF T H E GROWTH OF SILICA AND ΤΙΤΑΝΙΑ PARTICLES IN LOW M O L E C U L A R WEIGHT ALCOHOLS 291

Michael T. Harris, Osman A. Basaran, and Charles H. Byers

T H E FAST S O L - G E L SYNTHETIC ROUTE TO SUPPORTED GLASS FILMS: SYNTHETIC F E A T U R E S , SCOPE, APPLICATIONS AND MECHANISTIC STUDIES 297

Y. Haruvy and S .E. Webber

STABILITY O F AQUEOUS SUSPENSIONS OF HIGH S U R F A C E A R E A ZIRCONIA POWDERS IN T H E PRESENCE OF P O L Y A C R Y L I C ACID P O L Y E L E C T R O L Y T E 303

Michel M.R. Boutz, R.J .M. Olde Scholtenhuis, A.J.A. Winnubst, and A.J . Burggraaf

PRODUCTION O F SOLS FROM AGGREGATED ΤΙΤΑΝΙΑ PRECIPITATES 309 John R. Bartlett and James L . Woolfrey

P A R T I I I : C E R A M I C T H I N F I L M S , C O A T I N G S , M E M B R A N E S , AND F I B E R S

•STRESS AND PHASE TRANSFORMATION PHENOMENA IN O X I D E FILMS: R E A L - T I M E SPECTROSCOPIC MEASUREMENTS 319

Gregory J . Exarhos and Nancy J . Hess

• C H E M I C A L PROCESSING O F F E R R O E L E C T R I C NIOBATES E P I T A X I A L FILMS 331

Shin-Ichi Hirano, Toshinobu Yogo, Koichi Kikuta, Hisanobu Urahata, Yasuhide Isobe, Toshiyuki Morishita, Koji Ogiso, and Yasuhiro Ito

• C H E M I C A L PROCESSING AND PROPERTIES OF NANOCRYSTALLINE BaTi0 3 339

Z. Xu, H.K. Chae, M.H. Frey, and D.A. Payne

OPTIMIZATION O F S O L - G E L D E R I V E D PZT THIN FILMS BY T H E INCORPORATION OF E X C E S S PBO 345

G. Teowee, J.M. Boulton, and D.R. Uhlmann

E L E C T R I C A L AND OPTICAL PROPERTIES OF S O L - G E L PROCESSED Pb(Zr,Ti)0 3 FILMS 351

S.D. Ramamurthi, S .L . Swartz, K .R . Marken, J.R. Busch, and V . E . Wood

E L E C T R I C A L PROPERTIES OF C R Y S T A L L I N E AND AMORPHOUS Pb(Zr x Tii . x 0 3 THIN FILMS PREPARED BY T H E S O L - G E L TECHNIQUE 359

Yuhuan Xu, Chih-Hsing Cheng, Ren Xu, and John D. Mackenzie

PREPARATION O F BaTiO, AND PbTi0 3 THIN FILMS ON BaPb0 3 SUBSTRATES B Y T H E S O L - G E L METHOD AND THEIR PROPERTIES 365

M. Kuwabara, T. Kuroda, S. Takahashi, and T. Azuma

LOW T E M P E R A T U R E FORMATION OF F E R R O E L E C T R I C THIN FILMS 371 Chi Kong Kwok and Seshu B. Desu

MICROSTRUCTURAL VARIATIONS IN S O L - G E L PROCESSED LITHIUM NIOBATE THIN FILMS 377

Vikram Joshi, Grace K. Goo, and Martha L . Mecartney

•Invited Paper

viii

T H E GROWTH O F SINGLE C R Y S T A L - L I K E AND P O L Y C R Y S T A L K N b 0 3 FILMS VIA S O L - G E L PROCESS

Chih-Hsing Cheng, Yuhuan Xu, John D. Mackenzie, Jie Zhang, and LeRoy Eyring

PREPARATION AND CHARACTERIZATION O F S O L - G E L THIN FILMS OF K T i O P 0 4

Mark A. Harmer and Mark G. Roelofs

SYNTHESIS OF C U P R A T E BASED HIGH-T SUPERCONDUCTORS B Y P O L Y M E R I Z E D C O M P L E X METHOD

Masato Kakihana, Masahiro Yoshimura, Hiromasa Mazaki, Hiroshi Yasuoka, and Lars Börj Esson

APPLICATION O F ETHANOLAMINE METHOD FOR T H E PREPARATION O F INDIUM OXIDE-BASED SOLS AND FILMS

Yasutaka Takahashi, Hideo Hayashi, and Yutaka Ohya

GROWTH O F ORIENTED TIN O X I D E THIN FILMS FROM AN ORGANOTIN COMPOUND B Y SPRAY PYROLYSIS

Isao Yagi and Shoji Kaneko

S O L - G E L M U L T I L A Y E R S APPLIED B Y A MENISCUS COATING PROCESS

Jerald A. Britten and Ian M. Thomas

PHASE TRANSFORMATIONS IN S O L - G E L Y A G FILMS R.S. Hay

S T R U C T U R A L AND E L E C T R I C A L PROPERTIES OF Mn-Co-Ni-0 THIN FILMS PREPARED B Y DIP-COATING TECHNIQUE

Shoji Kaneko, Naoto Mazuka, and Tamotsu Yamada

M O L E C U L A R RECOGNITION ON ACOUSTIC W A V E D E V I C E S : MODIFIED Z E O L I T E - S I L I C A THIN FILMS WITH T A I L O R E D ADSORPTION PROPERTIES

Yongan Yan, Thomas Bein, Kelly D. Brown, Ray Forrister, and Jeffrey Brinker

S T R U C T U R E O F THIN S O L - G E L COATINGS NEAR T H E S U R F A C E OF SUBSTRATES

Hiroshi Hirashima and Takao Kusaka

L A S E R DENSIFICATION OF S O L - G E L D E R I V E D T i 0 2 - THIN FILMS N. Arfsten, B. Lintner, M. Heming, O. Anderson, and C.R. Otter-Mann

• C R Y S T A L L I N E THIN AND/OR THICK F I L M OF P E R V O S K I T E - T Y P E OXIDES B Y H Y D R O T H E R M A L E L E C T R O C H E M I C A L TECHNIQUES

Masahiro Yoshimura

E L E C T R O P H O R E T I C DEPOSITION OF S O L - G E L - D E R I V E D C E R A M I C COATINGS

Yining Zhang, C . Jeffrey Brinker, and Richard M. Crooks

CORROSION RESISTANT Z r 0 2 S O L - G E L COATING ON STAINLESS S T E E L

M. Atik and M.A. Aegerter

P R O T E C T I V E ZIRCONIA THIN FILMS ON M E T A L SUBSTRATES Andrea Tomasi, Paolo Scardi, and Fabio Marchetti

•Invited Paper

ix

PLASMA SPRAYED ALUMINA-ΤΙΤΑΝΙΑ COATINGS 485 T J . Steeper, A.J. Rotolico, J . E . Nerz, W.L. Riggs II , D.J. Varacalle, Jr. , and G.C . Wilson

A MICROPOROUS SILICA MEMBRANE 493 Wilhelm F . Maier and Herbert Ο. Schramm

T H E R M A L STABILITY OF SUPPORTED ΤΙΤΑΝΙΑ MEMBRANES 499 Krishnankutry-Nair P. Kumar, V . T . Zaspalis, F . F . M . De Mul, Klaas Keizer, and Anthonie J . Burggraaf

PREPARATION AND CHARACTERIZATION OF MICROPOROUS S O L - G E L D E R I V E D C E R A M I C MEMBRANES FOR GAS SEPARATION APPLICATIONS 505

R.S.A. De Lange, J.Η.A. Hekkink, Κ. Keizer, and A.J. Burggraaf

IMOGOLITE AS A M A T E R I A L FOR FABRICATION O F INORGANIC MEMBRANES 511

Jeffrey C . Huling, Joseph K. Bailey, Douglas M. Smith, and C . Jeffrey Brinker

S O L - G E L D E R I V E D PZT FIBERS 517 J.M. Boulton, G. Teowee, and D.R. Uhlmann

P A R T I V : AGING, D R Y I N G , AND CONSOLIDATION O F G E L S

•MECHANICS O F G E L S 527 George W. Scherer

T H E E F F E C T O F G E L AGING ON T H E PHYSICAL AND OPTICAL PROPERTIES O F A G E L - D E R I V E D GRIN GLASS 535

Mark A. Banash, Tessie M. Che, J . Brian Caldwell, Robert M. Mininni, Paul R. Soskey, Victor N. Warden, and Hui H. Chin

S O L - G E L FILMS WITH TAILORED MICROSTRUCTURES 541 Deborah L . Logan, Carol S. Ashley, and C. Jeffrey Brinker

PORE SIZE AND S U R F A C E T E X T U R E MODIFICATION O F SILICA VIA T R I A L K Y L S I L Y L A T I O N 547

Duen-Wu Hua and Douglas M. Smith

PORE S T R U C T U R E EVOLUTION OF SILICA G E L DURING AGING/ DRYING: E F F E C T OF S U R F A C E TENSION 553

Ravindra Deshpande, Douglas M. Smith, and C. Jeffrey Brinker

INTERPRETATION O F A E R O G E L SHRINKAGE DURING DRYING 559 Bharath Rangarajan and Carl T. Lira

PREPARATION O F LOW-DENSITY AEROGELS AT AMBIENT PRESSURE 567 Douglas M. Smith, Ravindra Deshpande, and C. Jeffrey Brinker

Hiroshi Hirashima and Kazumi Sudoh 573

P A R T V: C E R A M I C C O M P O S I T E S

L E U C I T E - P O L L U C I T E GLASS CERAMICS: A NEW F A M I L Y OF R E F R A C T O R Y MATERIALS WITH ADJUSTABLE THERMAL-EXPANSION 581

R . L . Bedard, R.W. Broach, and E . M . Flanigen

•Invited Paper

χ

SINTERING PROCESS AND MECHANICAL PROPERTIES FOR OXIDE-BASED NANOCOMPOSITES 589

Koichi Niihara, Atsushi Nakahira, and Masahiro Inoue

AMORPHIZATION AT T H E M E T A L - C E R A M I C I N T E R F A C E IN Nb—A1203 COMPOSITE THROUGH E X T E N S I V E INTERPHASE DIFFUSION 595

Abhijit Ray and Shy am K. Samanta

MODELING AND E X P E R I M E N T A L INVESTIGATIONS OF PRESSURE INFILTRATION O F S O L - G E L PROCESSED 3-D CERAMIC MATRIX COMPOSITES 601

Hsien-Kuang Liu and Azar Parvizi-Majidi

P A R T V I : H Y B R I D ORGANIC/INORGANIC M A T E R I A L S

* M A C R O - D E F E C T - F R E E CEMENT: A N O V E L ORGANOCERAMIC COMPOSITE 609

J . Francis Young and M. Berg

• M E T A L C O M P L E X E S IN OXIDIC MATRICES 621 Ulrich Schubert, Boris Breitscheidel, Hermann Buhler, Christian Egger, and Wlodzimierz Urbaniak

FORMATION O F HIGHLY DISPERSED METALS ON FUNCTIONALIZED SILICA SUPPORTS 633

Francois Rousseau, Z. Duan, M.J. Hampden-Smith, and A. Datye

E N E R G Y TRANSFER B E T W E E N E u 2 + , E u 3 + AND Rh6G IN SILICA, ZIRCONIA AND ALUMINA G E L S 639

W. Nie, Β. Dunn, C . Sanchez, and P. Griesmar

DIFFUSION O F CARBON MONOXIDE IN METALORGANIC THIN FILMS D E R I V E D FROM TITANIUM A L K O X I D E C A R B O X Y L A T E S 645

Charles D. Gagliardi, Dilum Dunuwila, C . K . Chang, and Kris A. Berglund

RIGIDOCHROMISM AS A PROBE OF GELATION, AGING, AND DRYING IN S O L - G E L D E R I V E D ORMOSILS 651

Stephen D. Hanna, Bruce Dunn, and Jeffrey I. Zink

SYNTHESIS AND CHARACTERIZATION OF ORGANIC D Y E DOPED SILICA GLASSES 657

Ilzoo Lee, Josephine Covino, and Michael D. Seltzer

DENSE X E R O G E L MATRICES AND FILMS FOR OPTICAL MEMORY 663 F. Chaput, J.P. Boilot, F . Devreux, M. Canva, P. Georges, and A. Brun

•TAILORING O F TRANSITION M E T A L ALKOXIDES VIA COMPLEXATION FOR T H E SYNTHESIS OF HYBRID ORGANIC-INORGANIC SOLS AND G E L S 669

C. Sanchez, M. In, P. Toledano, and P. Griesmar

S T R U C T U R E - R E L A T E D MECHANICAL PROPERTIES OF ORMOSILS B Y S O L - G E L PROCESS 681

Yi Hu and John D. Mackenzie

MONITORING O F HETEROPOLYSILOXANE THIN F I L M PROPERTIES USING R H E O L O G I C A L AND ACOUSTIC CHARACTERIZATION METHODS 687

C. Guizard, P. Lacan, J.M. Saurel, F . Hajoub, and L . Cot

•Invited Paper

xi

T H E E F F E C T O F ULTRASONIC RADIATION ON GELATION AND PROPERTIES O F ORMOSILS 693

Kazuki Morita, Y i Hu, and John D. Mackenzie

PREPARATION O F A R Y L - B R I D G E D POLYSILSESQUIOXANE A E R O G E L S 699

Douglas A. Loy, Kenneth J . Shea, and Edward M. Russick

CHARACTERIZATION O F MICROPOROUS SILICA G E L S PREPARED FROM MODIFIED SILICON A L K O X I D E S 705

W.G. Fahrenholtz and D.M. Smith

H Y P E R V A L E N T SILICONATE MATERIALS. SYNTHESIS AND CHARACTERIZATION O F N O V E L L A D D E R AND NETWORK IONOMERS 711

Kenneth J . Shea, Douglas A. Loy, and James H. Small

MULTIFUNCTIONAL (METH) A C R Y L A T E A L K O X Y S I L A N E S A NEW T Y P E O F R E A C T I V E COMPOUNDS 719

H. Wolter, W. Glaubitt, and K. Rose

CHARACTERISATION O F H Y D R O L Y S E D A L K O X Y S I L A N E S AND ZIRCONIUMALKOXIDES FOR T H E DEVELOPMENT O F U V - C U R A B L E S C R A T C H RESISTANT COATINGS 725

K. Greiwe, W. Glaubitt, S. Arnberg-Schwab, and K. Piana

MULTIFUNCTIONAL A C R Y L A T E A L K O X Y S I L A N E S FOR P O L Y M E R I C MATERIALS 731

K. Rose, H. Wolter, and W. Glaubitt

P A R T V I I : N O V E L R O U T E S T O NON-OXIDE C E R A M I C S

•PREPARATION O F NON-OXIDE CERAMICS B Y PYROLYSIS OF O R G A N O M E T A L L I C PRECURSORS 739

Leonard V. Interrante, Wayde R. Schmidt, Paul S. Marchetti, and Gary E . Maciel

C H E M I C A L L Y DESIGNED, UV C U R A B L E POLYCARBOSILANE POLYMERS 749

Kevin J . Thome, Stephen E . Johnson, Haixing Zheng, John D. Mackenzie, and M.F. Hawthorne

PROCESSING OF SiC-BASED FIBRES FROM POLYCARBOSILANE 755 Vasilios Kalyvas, J . C . Ko, G .C . East, J . E . Mclntyre, B. Rand, and F . L . Riley

P O L Y M E R - D E R I V E D SILICON CARBIDE FIBERS WITH IMPROVED THERMOMECHANICAL STABILITY 761

W. Toreki, C D . Batich, M.D. Sacks, M. Saleem, and G.J. Choi

SYNTHESES, STRUCTURES AND PROPERTIES OF POLYCARBOSILANES FORMED D I R E C T L Y B Y POLYMERIZATION OF A L K E N Y L S I L A N E S 771

John Masnovi, Xin Y . Bu, Kassahun Beyene, Paula Heimann, Terrence Kacik, A. Harry Andrist, and Frances I. Hurwitz

NMR CHARACTERIZATION OF SILICON CARBIDES AND CARBONITRIDES. A METHOD FOR QUANTIFYING T H E SILICON SITES AND T H E F R E E CARBON PHASE 777

C . Gerardin, M. Henry, and F . Taulelle

•Invited Paper

xii

HIGH T E M P E R A T U R E STABILITY OF O X Y C A R B I D E GLASSES 783 Hanxi Zhang and Carlo G. Pantano

SILICON O X Y C A R B I D E GLASSES FROM S O L - G E L PRECURSORS 789 F . Babonneau, G.D. Soraru, G. D'Andrea, S. Dire, and L . Bois

THE R O L E OF Si-Η FUNCTIONALITY IN O X Y C A R B I D E GLASS SYNTHESIS 795

Anant K. Singh and Carlo G. Pantano

CHARACTERIZATION O F HIGH S U R F A C E A R E A SILICON OXYNITRIDES 801

Peter W. Lednor, Rene de Ruiter, and Kees A. Emeis

ISOCYANATE-MODIFIED POLYSILAZANES: CONVERSION TO CERAMIC MATERIALS 807

Joanne M. Schwark and Mark J . Sullivan

REACTION SINTERING MECHANISM OF SUBMICROMETER SILICON POWDER IN NITROGEN 813

Yoshiyuki Yasutomi, Masahisa Sobue, and Jiro Kondo

SYNTHESIS OF ADVANCED CERAMICS IN T H E SYSTEMS Si-B-N AND Si-B-N-C EMPLOYING N O V E L PRECURSOR COMPOUNDS 821

H.-P. Baldus, O. Wagner, and M. Jansen

DESIGN AND SYNTHESIS OF C H E M I C A L PRECURSORS TO BORON CARBIDE 827

Xiaoguang Yang, Stephen Johnson, M. Frederick Hawthorne, Haixing Zheng, Kevin Thome, and J.D. Mackenzie

A L K Y N L SUBSTITUTED CARBORANES AS PRECURSORS TO BORON CARBIDE THIN FILMS, FIBERS AND COMPOSITES 833

Stephen E . Johnson, Xiaoguang Yang, M.F. Hawthorne, Kevin J . Thome, Haixing Zheng, and John D. Mackenzie

BORON CARBIDE NITRIDE D E R I V E D FROM AMINE-BORANES 839 Joachim Bill and Ralf Riedel

POLYMER PRECURSORS FOR ALUMINUM NITRIDE CERAMICS 845 James A. Jensen

OPTIMIZATION OF ALUMINUM NITRIDE T H E R M A L CONDUCTIVITY VIA C ON TR OL L E D POWDER PROCESSING 851

Theresa A. Guiton, James E . Volmering, and Kris K. Killinger

• E L E C T R O C H E M I C A L SYNTHESIS OF ALUMINUM NITRIDE IN LIQUID AMMONIA E L E C T R O L Y T E SOLUTIONS 857

Travis Wade, Jongman Park, Gene Garza, Claudia B. Ross, Douglas M. Smith, and Richard M. Crooks

E L E C T R O C H E M I C A L L Y PREPARED POLYMERIC PRECURSORS FOR T H E FORMATION OF NON-OXIDE CERAMICS AND COATINGS 869

Ralph Zahneisen and Christian Rüssel

ORGANOMETALLIC PRECURSORS TO VANADIUM AND TITANIUM CARBONITRIDE 875

Francois Laurent, Christophe Daures, Lydie Valade, Robert Choukroun, Jean-Pierre Legros, and Patrick Cassoux

•Invited Paper

xiii

NEW ROUTES TO GROUP IVA METAL-NITRIDES Chaitanya K. Narula

TITANIUM CARBIDE FROM C A R B O X Y L I C ACID MODIFIED A L K O X I D E S Tom Gallo, Carl Greco, Claude Peterson, Frank Cambria, and Johst Burk

PREPARATION O F TITANIUM CARBONITRIDE COATINGS B Y T H E S O L - G E L PROCESS

Haixing Zheng, Kris Oka, and John D. Mackenzie

XPS STUDY OF T H E NITRIDATION PROCESS O F A POLYTITANO-CARBOSILANE INTO Si-Ti-N-O CERAMICS

G. Granozzi, A. Glisenti, R. Bertoncello, and G.D. Soraru

P A R T V I I I : V A P O R P H A S E R O U T E S T O O X I D E C E R A M I C S

•MULTICOMPONENT C E R A M I C POWDER GENERATION B Y SPRAY PYROLYSIS

Shirley W. Lyons, J . Ortega, L . M . Wang, and T . T . Kodas

S T R U C T U R A L AND T H E R M A L INVESTIGATIONS ON BARIUM, COPPER AND Y T T R I U M MOCVD PRECURSORS

Alain Gleizes, Dominique Medus, and Sandrine Sans-Lenain

E L E C T R O N I C PROPERTIES O F OMVPE GROWN FILMS O F Y B a ^ O ^ O N 1" LaA10 3 SUBSTRATES

Willliam S. Rees, Jr. , Yusuf S. Hascicek, and Louis R. Testardi

REACTION OF BARIUM BIS(0-D1KETONATE) C O M P L E X E S WITH T H E S U R F A C E O F MAGNESIUM O X I D E

R.A. Gardiner, P.S. Kirlin, G .A.M. Hussein, and B . C . Gates

OMCVD ELABORATION AND CHARACTERIZATION O F SILICON CARBIDE AND CARBON-SILICON CARBIDE FILMS FROM ORGANOSILICON COMPOUNDS

R. Morancho, A. Reynes, M'b. Amjoud, and R. Carles

COMPUTATION, VISUALIZATION, AND CHEMISTRY O F E L E C T R I C FIELD-ENHANCED PRODUCTION O F CERAMIC PRECURSOR POWDERS

Michael T. Harris, Warren G. Sisson, and Osman A. Basaran

E F F E C T OF DOPANTS IN VAPOR PHASE SYNTHESIS O F ΤΙΤΑΝΙΑ POWDERS

M. Kamal Akhtar, S .E . Pratsinis, and S.V.R. Mastrangelo

DEPOSITION OF C E R A M I C FILMS B Y A N O V E L PULSED-GAS MOCVD TECHNIQUE

Kenneth A. Aitchison, James D. Barrie, and Joseph Ciofalo

AUTHOR INDEX

SUBJECT INDEX

•Invited Paper

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435

M O L E C U L A R RECOGNITION ON A C O U S T I C W A V E D E V I C E S : MODIFIED Z E O L I T E - S I L I C A THIN FILMS WITH T A I L O R E D

ADSORPTION PROPERTIES

Y O N G A N Y A N , a THOMAS ΒΕΙΝΛ* K E L L Y D. B R O W N , b R A Y F O R R I S T E R , b and C . J E F F R E Y B R I N K E R c a Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA b Department of Chemistry, University of New Mexico, Albuquerque, NM 87131, USA c Sandia National Laboratories, P. O. Box 5800, Albuquerque, NM 87185, USA

A B S T R A C T

Microporous thin films composed either of zeolite crystals embedded in sol-gel derived glass or of a molecular coupling layer, zeolite crystals and a porous silica overlayer, were formed on the gold electrodes of Quartz Crystal Microbalances (QCM). The microporosity of the thin films was characterized by in situ nitrogen and vapor sorption isotherms. Both preparation methods result in thin films with substantial microporosity. Selective adsorption based on molecular size exclusion from the microporous films could be achieved.

INTRODUCTION

Growing efforts are being devoted towards the design of chemical microsensors for environmental monitoring and industrial processing [1]. We have recently developed microsensors with molecular sieving functions in chemically selective layers on piezoelectric devices [2,3,4]. The successful design of microporous thin films retaining the molecular sieving capabilities of glass-embedded zeolites requires that several issues be addressed:

ο The glass matrix should not introduce additional, undesired porosity. ο The glass matrix should not clog the zeolite pores after deposition, i.e., the zeolite

porosity should be accessible from the gas phase, ο The attachment technique should result in a mechanically stable film that provides

effective coupling between the zeolite crystals and the oscillating QCM.

In situ nitrogen adsorption data of different zeolite-containing glass films were used to explore some of these aspects. In an extension of the glass-based composite approach we have also explored the attachment of zeolite crystals on sensor substrates by molecular means, i.e., by using a bifunctional coupling layer that binds to the substrate as well as to the zeolite crystals. As an example of such a system, we discuss a chemical microsensor with combined molecular sieve and selective surface interactions, based on novel silicalite-silica composite thin films on the active area of QCMs. The function of this sensor will be discussed in the context of selective responses towards ethanol.

In addition to the high sensitivity and selective size exclusion offered by molecular sieve films, the nature of the chemical surface interactions is important. In the thin films described below, interference from water (2.65Ä) which is smaller than ethanol (4.3Ä), could be minimized through hydrophobicity of the molecular sieve and the matrix (silica). The interplay of size exclusion and surface affinity thus provides highly selective adsorption suitable for sensor applications.

E X P E R I M E N T A L SECTION

The Q C M crystals used in the present study are AT-cut 5-9 MHz piezoelectric resonators, with 0.20 c m 2 gold electrodes deposited on chromium underlayers on opposite sides of the crystal. The sensitivity of a 6 MHz QCM according to the Sauerbrey relationship [5] is 12.3 ng Hz" 1 cm' 2 .

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The sol-gel derived, dip-coated composites were prepared from a suspension of silicalite (MFI) and Na-faujasite (FAU) in acid- or base-catalyzed (A2 and B2, respectively) TEOS sols as described previously [2b, 6]. Silicalite is a crystalline molecular sieve of composition S1O2 with a pore system of zig-zag channels along A (free cross-section ca. 5.1 χ 5.5 A), linked by straight channels along Β (5.3 χ 5.6 A), while F A U is composed of truncated Si/Al octahedra (sodalite cages) that form supercages with 7.5 A circular openings and 13 A internal diameter, with typical composition Na58Al58Sii340384 [7].

The preparation of the microporous layer for the ethanol sensor (MFI-EtOH) involved two steps: First, silicalite crystals (about 3 μιη diameter) were chemically anchored to the Q C M gold electrodes via a thiol-organosilane coupling layer [4]. The silicalite crystals bonded to the Q C M electrodes were then further coated with an amorphous, porous silica layer, prepared via sol-gel processing from Si(OEt)4 [8], so that stable microporous thin film composites were obtained. Nitrogen sorption at liquid nitrogen temperature on films where the microporosity is presaturated with ethanol revealed a nitrogen monolayer capacity of 0.0028 g/(g film), corresponding to only 9.8 m 2/g external surface area.

The selectivity and sensitivity of the composite film coated Q C M devices was determined by measuring the dynamic vapor sorption isotherms in a computer controlled helium vapor flow system. Q C M frequency changes of 0.1 Hz could be detected with a Keithley 775A frequency counter interfaced to a 386-based personal computer. Equilibrium of the vapor sorption was assumed when the frequency changes were less than 1.0 Hz in 30 seconds.

R E S U L T S AND DISCUSSION

Uncoated and glass-coated OCMs. Nitrogen adsorption isotherms of uncoated Q C M crystals are Type II and indicate surfaces with no porosity or with macropores. A polished 9 MHz Q C M crystal shows a B E T surface area of 2.0 cm 2 /cm 2 and a C constant of 20. This deviation from a perfectly flat surface is attributed to microscopic roughness of the devices. If the crystal is dip-coated with A2 sol and heated in air at 350°C to result in a coating mass of 1.55 μg/cm 2 , the B E T surface area does not increase. However, coating the crystal with a B2-sol derived glass film results in some porosity of the film when heated at the same conditions. The B E T surface area increases to 10 cm 2 /cm 2 .

The conditions of the heat treatment have a profound effect on the porosity of the glass films. Calcination in oxygen at 450 °C further increases the surface area of the films and introduces some microporosity. For instance, if a B2-derived film (45 μg/cm 2 ) is treated at 450 °C, the B E T surface area increases to 19 cm 2 /cm 2 (corresponding to 42 m 2/g; derived from the desorption branch), and micropore filling with 0.019 g N2/g film is observed. In the sorption branch, the micropore filling is 0.010 g N2/g. The difference between the adsorption and desorption branches found in several isotherms is probably associated with tortuous porosity of diameter close to that of nitrogen, such that hysteresis results.

Adsorption on Zeolite Sol-Gel Composites. Silicalite (MFI) and faujasite (NaY) type zeolites were embedded in different sol-gel derived glasses by dip-coating a suspension of the zeolites in the corresponding sol. The microporosity and external surface areas of these films were determined from α-plots of the nitrogen adsorption isotherms taken on the QCMs.

In general, the isotherms of the zeolite-glass composites show distinct microporosity as indicated by the initial steep rise of the adsorption at very low partial pressures. However, the isotherms differ from ideal Type I (Langmuir) adsorption which would be expected for zeolite crystals. After the initial steep rise the films are not saturated but continue to adsorb nitrogen in a fashion typical for many porous solids with Type IV isotherms. The continued adsorption indicates the presence of meso- and macroporosity that must result from combining the zeolites with the glass matrix.

Figure 1 shows a comparison of adsorption isotherms of silicalite (MFI) embedded in A2 glass and heated to 350 and 450 °C. Porosity parameters obtained from these isotherms are listed in Table 1. At about the same total coating weight, the adsorption isotherm resulting from lower temperature heating shows clearly much less adsorption in the micropore region (0.015 g N2/g film at p/po=0.10) than that resulting from high temperature heating (0.047 g N?Jg film at p/p o=0.10). Even if the desorption branch with the hysteresis is evaluated, higher

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Figure 1. Nitrogen adsorption isotherms on silicalite crystals embedded in A2-derived glass films calcined at 350 °C (top), and calcined at 450 °C (bottom).

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microporosity results from heating at higher temperature (0.021 vs. 0.014 g N2/g). The other important difference between the two isotherms relates to the desorption behavior. After heating at lower temperature, the desorption branch is offset by a strong hysteresis similar to that observed with some of the glass films themselves (see above) which is probably associated with a tortuous pore network of diameters close to that of nitrogen. On heating to 450°C in oxygen, the hysteresis in the low pressure region all but disappears, and some minor hysteresis in the mesopore region remains. Apparently the oxygen treatment removes residual organics from the films such that access to the zeolites is more facile.

The microporosity of these composite films is substantially less than that expected for a film consisting of 100% accessible silicalite (0.17 g N2/g). Since the weight fraction of the zeolite in the films is not known, it cannot be determined exactly how much of this decrease in microporosity must be attributed to potential pore clogging, ineffective acoustic coupling, or dilution with the glass film. Previous spectroscopic studies have established that zeolite porosity is accessible in similar films [2b].

Table 1. Microporosities and external surface areas of zeolite-glass composite films from nitrogen adsorption isotherms.3

Sample Coating Mass Microporosity External Surface Hysteresis μg /cm 2 g N2/g film m2/g film atp/po

Figure 2. Nitrogen adsorption isotherms on faujasite crystals embedded in A2-derived glass films calcined at 350 °C (top), and calcined at 450 °C (bottom).

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Ethanol selectivity. The selective vapor responses of a Q C M coated with the microporous, hydrophobic silicalite composite layer (MFI-EtOH) are illustrated by the sorption of pure vapors of ethanol (ca. 4.3 Ä diameter), 2,2,3-trimethylpentane (iso-octane, ca. 6.2 A) and water (2.65 A) in the range of 0-2000 parts per million (ppm) in moles (Figure 3). The QCMs were pre-degassed at 170 °C in a helium flow for 20 min. The sorption of ethanol (top curve) shows the largest and fairly linear response as a function of vapor concentration. A 50.4 ppm ethanol vapor concentration results in 0.024 μg sorption per fig coating layer, 309 ppm cause further mass increase to 0.050 μg/μg, and 722 ppm to 0.076 \Lgl\\,%, which is about 1000 times higher than the alcohol response of a bare QCM.

In contrast, the response of the microdevice to iso-octane (bottom line) exhibits an almost negligible change with increasing vapor concentration. As the concentration of iso-octane is varied from 200 ppm to 700 ppm, the amount adsorbed changes from 1.66 ng^g to 1.87 ng^g, which is a mass increment of only 0.6% of that of alcohol sorption at the same concentrations. The results show that novel sensing layers with highly effective molecular sieving functions and very low external surface areas can be designed. Sorption of the small water molecules (middle line) shows also a small response. Although water sorption slightly increases with increasing concentration (at the two concentrations given above, the capacity is respectively 12.2 and 15.5 ng^g), it already approaches a rectilinear isotherm at these low concentrations. This behavior differs drastically from the sorption of ethanol.

The microsensor design discussed in this communication shows that highly selective responses can be achieved when microporous adsorption is combined with tailored surface interactions in composite films. Exploration of additional selective interactions in microporous glass composites is in progress.

Funding from the National Science Foundation (Division of Materials Research) and from the Department of Energy (New Mexico W E R C program) for this research is gratefully acknowledged.

Vapor concentration in PPM by mole

Figure 3. Sorption isotherms of ethanol (O), water (Π) and isooctane (Δ) on a Q C M coated with 168 μg /cm 2 of MFI-EtOl I composite at 20 °C.

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R E F E R E N C E S

1 For recent reviews see: (a) J. Janata, Anal. Chem. £2, 33r (1990). (b) R. C . Hughes, A. J. Ricco, M. A. Butler and S. J . Martin, Science 254, 75 (1991).

2 (a) T. Bein, Κ. Brown, G. C. Frye and C. J. Brinker, U . S. Patent Application 07/580,373, allowed on Jan. 23, 1992. (b) T. Bein, Κ. Brown, G. C. Frye and C . J . Brinker, J . Am. Chem. S o c . l l l , 7640 (1989).

3 T. Bein, Κ. Brown and C. J . Brinker, Stud. Surf. Sei. Catal. 49, P. A. Jacobs, and R. A. Van Santen, Eds.; (Elsevier, Amsterdam, 1989), p. 887.

4 Y . Yan and T. Bein, J. Phys. Chem., in press. 5 Af= -2f 0 2 AmA- 1 (pq^)- 1 / 2 , where Af is the frequency shift, f 0 the parent

frequency of the QCM, Am the mass change in g, A the piezoelectrically active area in cm 2 , pq the density (2.648 g enr 3 ) and μς the shear modulus (2.947 x l O 1 1 dynes cm- 2) for AT-cut quartz. See: G. Sauerbrey, Ζ. Physik 155, 206 (1959).

6 C . J. Brinker and G. W. Scherer, Sol-Gel Science. (Academic Press, San Diego, 1990), p. 110.

7 (a) Ε. M. Flanigen, J . M. Bennett, R. W. Grose, J. P. Cihen, R. L . Patton, R. M. Kirchner and J. V. Smith, Nature 271, 512 (1978). (b) W. M. Meier and D. H. Olson, Atlas of Zeolite Structure Types, 2nd Edition, (Butterworths, 1987).

8 T. Bein and Y . Yan, U.S. Patent in preparation.