|
Showing 1 - 3 of
3 matches in All Departments
The present Supplement Volume Beryllium A 3 continues and completes
the description of the physical properties of the element, begun in
Supplement Volume A 2, 1991, and also treats the electrochemical
behavior of the metal. The unique combination of the Be properties,
which was pointed out in Supplement Volume A 2, is also
demonstrated in the following chapters of this Volume A 3: 13.
Electrical Properties 14. Electronic Properties 15. Optical
Properties. Emission and Impact Phenomena 16. Electrochemical
Behavior Starting with the electrical properties, Be isarather good
electrical conductor in centrast to what might be expected.
Superconductivity was studied, especially on films. Quantum
effects, which are more pronounced in Be than in most other metals,
are the reason for numerous in vestigations of the
magnetoresistance and the magnetic-breakdown effect. The basis for
many of the characteristic properties is the unique nature of
bonding in Be as a consequence of its peculiar electronic structure
and the special shape of its Fermi surface which also gave rise to
further numerous studies. Detailed cluster calculations were per
formed to better understand the bonding in the metal. Regarding the
optical properties, the high reflectivity of Be, particularly in
the infrared region, makes it attractive for the fabrication of
precision optical surfaces (mirrors); it is also useful for
solar-collector surfaces in spacecraft applications. Emission and
electron-and ion impact phenomena as well as neutron optics are
also discussed.
The volume Rare Earth Elements C 11 deals with the compounds and
systems of the rare earth elements with boron, i.e. borides,
borates, and associated alkali double compounds. As in all earlier
volumes of "Rare Earth Elements" Series C (Seltenerdelemente Reihe
C) comparative data are presented in sections preceding treatment
of the individual compounds and systems. Topics of the present
volume C 11 a are the comparative data on the borides and the
individual sections on the systems and borides containing Sc, Y,
and La. The individual sections for the systems and borides with Ce
to Lu can be found in the following volume C 11 b together with the
borates, its alkali double compounds and other compounds containing
Ce to Lu, boron and elements related by the Gmelin system. The most
extensively studied borides treated in the comparative sections are
of the type MB6. These rare earth hexaborides are refractory
compounds and some of them, especially LaB6, are good thermionic
emissive materials or exhibit other interesting physical
properties. The most comprehensive chapter in the individual
sections of volume C 11 a deals with LaB6, which is a well-known
thermionic material of great practical importance with high
electron emission efficiency and an excellent stability in the
surface composition at high temperatures. The effects of
preparation conditions, composition, temperature, surface
structures, surface treatment, and of the atmosphere on the
thermionic emission are studied thoroughly. Another important item
of the LaB6 chapter is the electronic structure, which often serves
as an example for the other rare earth hexaborides.
This voLume continues the description of the physicaL properties of
tungsten metaL and covers specificaLLy surface properties, eLectron
emission, and fieLd evaporation. Tungsten surfaces are probabLy the
most extensiveLy studied metaL surfaces. RecentLy, experimentaLists
and theorists have focused their interest on the atomic structure,
Lattice dynamics, and eLectronic properties of the W(100) surface.
WhiLe the structure of the recon- structed Low-temperature surface
is weLL estabLished, there are still unresoLved probLems concerning
the structure at and above room temperature, the nature of the
phase transition, and the driving force for the reconstruction.
Other Low-index tungsten surfaces have been studied in much Less
detail. There are numerous and partLy confLicting data on the
surface energy, the seit-diffusion parameters, and the work
function of singLe-crystaL and poLycrystaL tungsten surfaces. ELec-
tron emission, which is of fundamentaL importance for many
appLications, comprises therm- ionic, fieLd, photofieLd, and
photoeLectric emission as weLL as emission induced by impinging
eLectrons, atoms, or ions. Pioneering work in areas Like thermionic
or fieLd emission is comprehensiveLy discussed. Very recent studies
of vaLence-band and core-LeveL spectra moreover provide detaiLed
information on intrinsic surface properties. FieLd evaporation
phenomena are treated at the end of this voLume. Frankfurt am Main
Woltgang HuisL November 1993 fable of Contents Page 1 Atomic
Structure, LaHice Dynamies, and Electronic Structure of Tungsten
Surfaces 1 1.1 W(100) ...1.1.1 Atomic Structure. Reconstruction and
Relaxation Survey ...
|
You may like...
Midnights
Taylor Swift
CD
R425
Discovery Miles 4 250
|