Wolfgang Kurtz – författare

In the first part of this volume the nitrogen-containing compounds of molybdenum are described. The Mo-N system shows that M0 N and MoN are the stable nitrides. MOlybdenum 2 metal dissolves nitrogen to some extent but only at high temperatures. To get better insight into the reactions between nitrogen and molybdenum, the solubility, diffusion, adsorption and desorption phenomena, and ion bombardment are included in the section of the Mo-N system. M0 N has a large range of homogeneity toward lower nitrogen concentrations. The black 2 hexagonal MoN has only a narrow range of homogeneity. In addition some molybdenum compounds containing nitrogen and oxygen are known. The second part contains a full description of the compounds of molybdenum with fluorine. The fluorides MoF n with n ~ 2 are metastable while those with n = 3 to 6 are stable and have been observed in the Mo-F system. Pure MoF can exist without traces of oxygen, in co nt rast 3 to earlier assumptions. MoF was unambigously prepared and characterized in 1957. Its crystal 4 structure is still unknown. MoF is often contaminated with the oxide fluoride MoOF and it is s 4 difficult to remove. Even sm all amounts affect the properties of MoF . MoF , which is liquid at s 6 room temperature and solidifies to a "plastic" crystal modification below ca. 17SC, is the most investigated of all the molybdenum fluorides.

The present volume continues the description of the chemical reactions of eiemental tungsten started with "Tungsten" Suppl. Vol. A 7. It covers the reactions with the metallic elements from zinc to actinoids. The treatment includes phase diagrams, bulk reactions, and surface processes which again are of outstanding importance in most systems. The raader is referred to the introductory remarks on pp. X/XI. Frankfurt am Main Ernst Koch November 1987 Introductory Remarks Abbreviations In order not to overload the text, the following abbreviations are sometimes used without definitions in the present volume, in addition to the abbreviations usual in the Gmelin Handbook. a. c. alternating current AE Auger electron Auger electron spectroscopy(ic) or spectrum AES bcc body-centered cubic CPD contact potential difference counts per second cps d. c. direct current DTA differential thermoanalysis Fermi Ievel EF EI electron impact ELS electron energy loss spectroscopy or spectrum EMF, emf electromotive force fcc face-centered cubic FE field emission field electron (emission) microscope(ic) FEM FES field emission spectroscopy FIM field ion microscope(ic) F-N Fowler-Nordheim hcp hexagonal close-packed 6 L Langmuir=1·10- Torr·s LEED low energy electron diffraction monolayer ML PES photoelectron spectroscopy PSD photon-stimulated desorption RHEED reflection high energy electron diffraction room temperature RT SI secondary ion SIMS secondary ion mass spectrometry TDS thermal desorption spectroscopy(ic) or spectrum TE thermionic emission total energy distribution TED UHV ultra-high vacuum UPS ultra-violet photoelectron spectroscopy(ic) or spectrum XPS X-ray photoelectron spectroscopy(ic) or spectrum Gmelin Handbock WSuppl. Vol.