DRY HIGH PRESURE METHODS OF SOLID STATE SYNTHESIS

1. DRY HIGH PRESURE METHODS OF SOLID STATE SYNTHESIS • Pressures up to Gbars accessible, at high T with insitu observations by diffraction and spectroscopy - can probe chemical reactions, structural transformations, crystallization, amorphization, phase transitions - kinetics and mechanism of solid state transformation - think about this? Nucleation and growth of one phase within another!!! • Methods of obtaining high pressures: anvils, diamond tetrahedral and octahedral pressure transmission, shock waves, explosions • Go to another planet, recall hydrogen is metallic at 100 Gbars (explain why this is so?)

2. DRY HIGH PRESURE METHODS OF SOLID STATE SYNTHESIS • Pressure techniques useful for synthesis of unusual structures, metastable, yet stable when pressure released (why?) • Often high pressure phases have a higher density, higher coordination number • In fact ruby is used for calibrating a high pressure diamond anvil, so explain how this method works?

3. HIGH PRESSURE DIAMOND ANVIL SOLID STATE SYNTHESIS

4. HIGH PRESSURE POLYMORPHISM FOR SOME SIMPLE SOLIDS • Solid Normal structure Typical transformation High P structure and coord. no. conditions P kbar, T °C and coord. no. • C Graphite 3 130 3000 Diamond 4 • CdS Wurtzite 4:4 30 20 Rock salt 6:6 • KCl Rock salt 6:6 20 20 CsCl 8:8 • SiO2 Quartz 4:2 120 1200 Rutile 6:3 • Li2MoO4 Phenacite 4:4:3 10 400 Spinel 6:4:4 • NaAlO2 Wurtzite 4:4:4 40 400 Rock salt 6:6:6

5. DIAMONDS ARE FOREVER

6. P-T PHASE DIAGRAM OF CARBON

7. RELATIVE STABILITY OF GRAPHITE AND DIAMOND Graphite sp2 Diamond sp3

8. SO WHY IS IT SO DIFFICULT TO TRANSFORM GRAPHITE INTO DIAMOND? • Industrial diamonds made from graphite around 3000oC and 130 kbar • Problem is activation energy required for a sp2 3-coordinate to a sp3 4-coordinate structural transformation is very high, requires extreme conditions • Ways of getting round the difficulty • Squeezing and heating buckyball whose carbons are already intermediate between sp2-3. In the case of C60, diamond anvil, 20 GPa instantaneous transformation to bulk crystalline diamond, highly efficient process, fast kinetics • Using 1% CH4/H2 microwave discharges to create reactive atomic carbon whose valency’s are more-or-less free to form sp3 diamond, in this case with atomic hydrogen this is the route for making diamond films

9. P > 20 GPa R.T. CHIMIE DOUCE WITH DIAMOND SYNTHESIS

10. APPLICATIONS OF SUPERHARD DIAMOND MATERIALS -CRYSTAL, POWDER, FILM  Superabrasives (200 t/year)  Gemstones  Heat sinks for microelectronics  Radiation windows  Speaker tweeters  Mechanical bearings  Surgical knives  Coatings - frying pans  Semiconductors - wide band gap

11. HYDROTHERMAL SYNTHESIS AND CRYSTALLIZATION OF ZEOLITES • Typical zeolite synthesis • NaAl(OH)4(aq) + Na2SiO3(aq) + NaOH(aq), 25oC, condensation-polymerization, Na(H2O)n+ template  • Naa(AlO2)b(SiO2)c.NaOH.H2O(gel)  25-175oC, hydrothermal crystallization of amorphous gel • Nax(AlO2)x(SiO2)y.zH2O(crystals)

12. HYDROTHERMAL SYNTHESIS AND CRYSTALLIZATION OF ZEOLITES • Nax(AlO2)x(SiO2)y.zH2O(crystals) • Extraframework charge-balancing cations, templates, ion-exchangeable • Framework Al(III)O4 and Si(IV)O4 tetrahedral primary building-blocks • (AlO2)- and SiO2 stoichiometry for building blocks as bridging O • Occluded water, removed by 25-500oC vacuum thermal dehydration • Organic cationic templates, quaternary alkylammonium, structure-directing, space-filling, charge-balancing, discovery of new structures

13. Corner sharing SiO4/AlO4 tetrahedra Cation binding site in six ring resembles crown ether-cation complex Six ring shorthand notation Mq+ ZEOLITE BUILDING UNITS SHORTHAND NOTATION

14. BUILDING-BLOCK APPROACH TO ZEOLITE SYNTHESIS, STRUCTURES AND PROPERTIES • Primary tetrahedral units, AlO2-, SiO2, PO2+ and so forth, combined to give open-framework and framework charge, balanced by extraframework cations • Existence of primary and secondary units in a synthesis mixture including: • 4R, 6R, 8R, D4R, D6R, 5-1, cubooctahedron

18. ZEOLITE POST MODIFICATION FOR CONTROLLING PROPERTIES OF ZEOLITES • Tailoring channel, cage, window dimensions, adsorbents, gas separation, purification • Tuning Brnsted acidity, hydrocarbon cracking • Ion exchange capacity, Lewis acid-base character, water softening, detergents • Size-shape selective catalysis, separations, sensing -reactant, product, transition state selectivity

19. ZEOLITE POST MODIFICATION FOR CONTROLLING PROPERTIES OF ZEOLITES • Host-guest inclusion, atoms, ions, molecules, radicals, organometallics, coordination compounds, clusters, polymers (conducting, insulating), nanoreaction chambers • Advanced zeolite devices, electronic, optical, magnetic applications • Entry to nanoscale materials, size tunable properties, QSEs

22. SHAPE SELECTIVE CATALYSIS - REACTANT, PRODUCT, TRANSITION STATE SELECTIVITY

23. ALKYLATION OF TOLUENE BY METHANOL - SHAPE SELECTIVE CATALYTIC PRODUCTION OF p-XYLENE Used for manufacture of terephthalic acid for production of polyester fibers Snug fit can diffuse through channels

24. Shape slective dehydration of normal and iso-butanols to butenes over calcium ion exchanged zeolite A and zeolite Y

25. DIAMOND LATTICE OF 1.3 nm SPHERICAL SUPERCAGES IN ZEOLITE Y

26. SIMPLIFIED NOTATION FOR ZEOLITE ION EXCHANGE, BRNSTED ACID SITE FORMATION AND DEALUMINATION TO HIGH SILICA ZEOLITES

28. The changing face of zeolite science and technology - pore and channel dimensions way beyond 1 nm - periodic table of compositions

29. LAYER-BY-LAYER GROWTH OF ZEOLITE THIN FILMS FOR PERMSELECTIVE MEMBRANES

31. ORGANICS ORGANIZING INORGANICS ABIOGENIC

32. Mq+ links building blocks via S binding and structure directed by Me4N+ template Ge4S104- adamantanoid building block ARCHITECTURAL CONTROL - TEMPLATE DIRECTED TRANSFORMATION OF BUILDING BLOCKS TO OPEN FRAMEWORK SOLIDS

33. LEARNING FROM NATURE - TEMPLATING INORGANICS WITH SINGLE MOLECULES AND SUPRAMOLECULAR ASSEMBLIES