Synthesis and Characterization of Advanced Materials (1984) / Chapter Skim
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Panel 2: Scientific Challenges Arising from Technological Needs
Panel 2: Scientific Challenges Arising from Technological Needs
Pages 44-58
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From page 44... ...
The purpose of characterization is generally twofold: to understand closely related materials on the basis of their chemical bonding, atomic structure, and microscopic and macroscopic perfection and to improve and specify materials for particular applications.
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From page 45... ...
Si and GaAs) o Magnetic materials o Ferroelectric materials o Piezoelectric materials o High-strength and electronic ceramics o Metallic organic materials, especially those with established connections between bonding, structure, and properties, where synthesis of desired structures is critical, for example, linear chain conductors and layered compounds o Inorganic polymers, for example, SNX o Active organic polymers, such as resists and piezoelectric materials 0 New superconducting materials, particularly binary and ternary compounds, alloys, and solid solutions 0 High-performance composites o Amorphous materials for which the preparation requirements are unusual, such as amorphous metals and fibers 0 Alloys and composites for which specialized care in preparation and processing control is essential o Some single-crystal materials o Various other inorganic materials such as oxides, layered materials, tunnel junction materials.
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From page 46... ...
Another area of SACAM contributions to electronics is the preparation of magnetic materials. The descriptive and structural chemistry of oxide magnetic materials, alloys, and intermetallic compounds was developed through decades of continuous work.
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From page 47... ...
The exploitation of this crystalline anisotropy required the development of powder-metallurgy techniques for the consolidation of these highly reactive materials and the exploitation of new chemistry to produce fine powders at reasonable cost from inherently inexpensive rare earth oxides. Although these materials are intrinsically more expensive than oxide materials, their high coercive force makes them extremely resistant to demagnetization and thus cost effective for many device applications.
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From page 48... ...
The key to these advances was the discovery that MgO inhibited grain growth in A12O3 and the subsequent careful exploitation of this discovery' 80 that it 'could be used under~actual processing conditions.' Other examples of SACAM achievements based on detailedunderstanding of ceramic processing include the efficient fabrication of UO2 fuel rods for fission reactors, ZrO2 ceramics for oxygen detectors, which find use in emission control in internal combustion engines, ballistic armor for military and civil police applications, tungsten carbide tool tips for high-speed machining, and 8-A12O3 and related ceramic materials for solid-state battery electrodes. The key has been the careful control of grain structure to make a useful polycrystalline material at a cost low enough to permit exploitation.
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From page 49... ...
Hi.. 3.~49 The efficient conversion of petroleum into the variety of fuels needed by modern industry and the conversion of petroleum feedstocks to petrochemicals and polymeric materials depend on the availability of highly specific solid catalysts.
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From page 50... ...
Historically, the major body of phase-state information has been obtained by measurement and computation of bulk properties, augmented, when appropriate, with simple rules for predicting phase type from electron concentration and pre-existing knowledge of crystal structure. Crystal structure cannot be predicted a priori except in the s implest of cases .
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From page 51... ...
Modern analytical tools, such as the electron microscope, microprobe, and Auger spectrometer, which permit chemical and structural analysis on a localized scale, are now being effectively used in studying structure and composition of grain boundaries and other internal interfaces in solids. Primary and secondary recrystallization of metals and alloys, such as copper, nickel, and transformer steels, are controlled in part by segregation of minor additives, both intentional and inadvertent.
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From page 52... ...
Several driving forces important to the future of the electronic materials industries have as their central feature the need for improved advanced materials. Probably foremost is the continuing increase in the scale of integration of silicon integrated circuits (SICs)
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From page 53... ...
These developments will come about only as a result of increases in the memory and calculating power obtainable per unit investment. Less costly data processing results directly from putting more circuit functions on a single Si chip.
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From page 54... ...
There are many other opportunities for SACAM in electronics. Examples include high-speed circuit elements, such as Josephson logic junctions, and new display mater ials.
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From page 55... ...
New energy sources, including fission, fusion, geothermal energy, and ocean thermal energy, and new approaches to higher-efficiency energy generation, such as magnetohydrodynamics, all involve demanding temperature, corrosion, or radiation environments. The ability of the SACAM community to provide nitrides, carbides, silicides, superalloys, and composites for these critical areas could well determine the extent and reliability of advances in these technologies.
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From page 56... ...
However, improvement in mechanical properties, such as strength, ductility, and durability, and improved control of electronic properties over wider ranges would greatly increase the economic attractiveness and utility of ceramic materials. Research techniques, many of them originally used in physical metallurgy, are unraveling many of the mysteries of grain growth and control during densification and sintering in ceramics.
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From page 57... ...
SACAM researchers would like to begin to look at catalytic material with a complexity approaching that of catalysts used in technology; however, it is essential that these materials be prepared reproducibly with stoichiometry and defect chemistry well characterized and understood. The need for theoretical work of many sorts is obvious.
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From page 58... ...
A large fraction of the sabbaticals taken by SACAM researchers in U.S. industry involve substantial interaction with the European SACAM community.
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