AWARDED THE WINNERS OF THE XVII EDITION OF THE ITALGAS PRIZEdrasmuss/ES360 Spring... · AWARDED THE WINNERS OF THE XVII EDITION OF THE ITALGAS PRIZE ♦Science and Environment, of

AWARDED THE WINNERS OF THE XVII EDITION OF THE ITALGAS PRIZE♦ Science and Environment, of the amount of 80,000 Euro, awarded to scientists and researchers that have attained relevant results in the field of research on Energy and the relation with the Environment.The Scientific Commission has awarded the prize to Daniel G. Nocera, Keck Professor of Energy, Department of Chemistry, MIT (USA), who accomplished a work on molecular chemistry for the production of renewable energy. The research has attained results in the development of the first photocatalytic cycle for the production of hydrogen.

BS (Chemistry, RU, 1979)

•You are part of an engineering team at NASA whose assignment is to find a way to keep NASA shuttles from getting too hot from sunlight while in orbit and from burning up during reentry to atmosphere. The engineering design of suitable insulation will not be easy.

•Insulation must withstand 2200 oF (1204 oC).•Insulation MUST BE LIGHT!•Insulation must a ceramic.

CeramicsCeramics

• Ceramics: solids having covalently bonded networks and/or ionic lattices

• Typical examples: alumina (Al2O3), silicon carbide (SiC),zirconia (ZrO2) and beryllia (BeO), silica (SiO2).

• Ceramicsare inorganic, nonmetallic, solids, crystalline, amorphous (e.g.

glass), hard, brittle, stable to high temperatures, less dense than metals, more elastic than metals, and very high melting

• Lightest ceramics are produced by sol-gel processes

polymer

Remove liquid

Remove liquid

Low density “aerogel”

Higher density

Both of these SiO2 materials have lots of open spaces and are MUCH lessdense (lighter) than sand (SiO2)NASA tiles are a composite ceramic: Silica aerogel reinforced with fibers

(text: p.470)

Ceramic Composites• Composite: two or more materials making up a ceramic.• Result: tougher ceramic.• Most effective method: add fibers to ceramic material.

Example: SiC fibers added to alluminosilicate glass.• Fiber must have a length ≥100 times its diameter.

www.cffls.uky.edu/C1/2002%20meeting/ Utah%20Brian%20Dunn.pdf

Chemistry of aerogel formation from reaction of Si(OCH3)4 with H2O

See eqn. 12.8 in text:Condensation reactionsmake polymers withSi-O-Si bonds

White tiles reduce solar heating in orbit

Black tiles maximize radiative heat loss during reentry

•Your job: keep NASA shuttles from getting hot while in orbit and burning up during reentry to atmosphere.•Insulation must withstand 2200 oF (1204 oC).•Insulation MUST BE LIGHT!•Insulation must a ceramic.

JPL's newest version of Aerogel is 99.8 percent air and is a stiff foam made from silicon dioxide and sand. Its density is just 3 milligrams per cubic centimeter (1000x less dense than glass). Its melting point is 2,200 degrees Fahrenheit (1,200 degrees Centigrade).

Scientist Samual Kistler invented the original Aerogel in 1932. Monsanto later bought the rights to the material and used it as an insulator in picnic coolers and as a thickening agent in napalm bombs.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., got involved with Aerogel as it looked for lightweight material to use on the 1997 Mars Pathfinder rover mission and actually improved the material.

Some applications of ceramics• Used in cutting tool industry.• Used in electronic industry (semiconductor integrated

circuits usually made of alumina).• Used to make tiles on the space shuttle.

• Superconductors show no resistance to flow of electricity.

• Superconducting behavior only starts below the superconducting transition temperature, Tc.

• Meissner effect: permanent magnets levitate over superconductors. The superconductor excludes all magnetic field lines, so the magnet floats in space.

Superconducting Ceramic Oxides

•Below some temperature Tc, all electrical resistance vanishes!• Infinitely large currents can flow without any losses.• Big currents generate big magnetic fields. • Superconducting magnets have led to important new technologies –

including magnets for MRI imaging, MAGLEV trains that travelabove the rails.

N2(l) boils @ 90oK

http://depts.washington.edu/chemcrs/bulkdisk/chem162U_spr04/handout_Lecture_Apr_19_6x.pdf

• Thin films generally have a thickness between 0.1 µm and 300 µm.

• Useful thin films must– be chemically stable,– adhere well to the surface,– be uniform,– be pure,– have low density of imperfections.

Thin Films

Uses of Thin Films• Microelectronics (conductors, resistors and

capacitors).• Optical coatings (reduce reflected from a lens).• Protective coatings for metals.• Increase hardness on tools.• Reduce scratching on glass.

•(Low-E) coatings: thin, almost invisible, metal or metallic oxide layers

•Reduce radiative (infrared) heat loss through window glass

•Layers formed by sputtering onto glass surfaces

•Layers pass most of visible light

Sputtering

Formation of Thin Films• Vacuum Deposition

– Material is placed in one chamber and the objects to be coated in another.

– Pressure is reduced, the material is heated, vaporizes, and condenses on the object to be coated.

– Examples: MgF2, Al2O3, and SiO2.

Formation of Thin Films• Chemical Vapor Deposition

– Surface is coated with a volatile compound at a high temperature

– On the surface, the compound undergoes a chemical reaction to form a stable, non-volatile coating.

– Examples:TiBr4(g) + 2H2(g) → Ti(s) + 4HBr(g)SiCl4(g) + 2H2(g) → Si(s) + 4HCl(g)SiCl4(g) + 2H2(g) + 2CO2(g)→ SiO2(s) + 4HCl(g) + 2CO(g)3SiH4(g) + 4NH3(g) → Si3N4(s) + 12H2(g)

Metallic layer

Polar covalently-bonded ceramic layer

http://www.lhup.edu/~dsimanek/chapman.htm

A web site giving lots of tips on how to study physics, take notes,prepare for lectures, learn definitions and concepts, study for exams,and other items. All of these apply to the study of chemistry – andprobably most of the upper level technical courses you may take.

That’s all folks for now.

Next semester will include:•Modern battery designs (for cell phones, laptops)•Semiconductors•Laser diodes•Xerography•Solar energy conversion (solar cells)•Cd’s and new generations of DVD’s •LED computer displays•Biomaterials at Rutgers•CPU chip research at Rutgers