Carbide magnetic properties

Many other atom-probe analyses of different phases in different types of steels exist as steels are one of the most important materials. It is possible to investigate how the magnetic properties of alloys are correlated to the microstructures of different phases in the alloys.57,58,59 The chemical contents, growth process and structures of metallic carbides in different alloy steels have been studied with the field ion microscope and the atom-probe field ion microscope.60 61 62 63 We refer the reader to some of the original papers published on these subjects. 

The previous section showed that the physical properties of the carbides and nitrides differed substantially from those of the parent metals, and resembled those of ceramic compounds. The electronic and magnetic properties of the carbides and nitrides provide an interesting contrast, because here there are similarities with the metals. 

Carbides, Silicides, and Related Compounds. Niobium carbide has been obtained by deposition from a NbCl4-H2-CH4 mixture. There has been a review of the electrical, thermoelectrical, and magnetic properties of MC-TaC systems (M = Hf or... 

Altliough activated adsorjition does not necessarily precede catalysis, the investigation of the activated adsorption as well as the investigation of adsorption by means of IR spectra and of magnetic properties of chemisorbed molecules, must be important for catalysis. Of no less importance is the study of bulk chemical compounds which are similar to the supposed surface compounds, for example, the alcoholates in the dehydration of alcohols. From this point of view, one should study the properties of nitrides, carbides, hydrides, and other similar compounds. These studies are necessary because they permit one to make a judgment of the chemical forces which are displayed under conditions similar to catalysis. It should be borne in mind, however, that this evidence is indirect, as it refers not to the catalytically active centers themselves but to the surface, which is much larger they refer not to the activated complex, but to more stable compounds formed with the help of a catalyst. 

In contrast to the physical properties, transition metal carbides and nitrides possess electric and magnetic properties that are often similar to metals. For example, electrical resistivities of Ti or W are 39 and 5.39 pft cm at room temperamre, while their respective carbides have only slightiy higher resistivities of 68 and 22 p,fl cm. For comparison the electrical resistivity of the hard SiC ceramics is significantly higher (1000 pfi cm). 

Altounian, Z., Chan, X., Liao, L. X., Ryan, D. H. Strom-Olsen, J. O. (1993). Structure and magnetic properties of rare earth iron nitrides, carbides and carbonitrides. Journal of Applied Physics, 73, 6017-22. 

Investigations of the electrical and magnetic properties of the metal-rich rare earth halides have focussed on the Gd halide hydrides (deuterides) and carbides, and the Tb halide hydrides (deuterides). Table 10 summarizes some significant electrical and magnetic data of Gd, Tb, Sc and Y compounds. The binary compounds, the carbide halides with cluster chains or planes, and the hydride halides are discussed in detail. 

Mir] Resistometry, X-ray analysis, magnetic properties of carbides extracted by dissolution of metallic matrix 0 - 20.4 mass% Cr and 0.46 - 1.54 mass% C... 

The majority of metal phosphides have a metal arsenide analogue which they usually resanble in properties and structure (Table 8.2). Metal phosphides, arsenides and nitrides not infrequently exhibit properties similar to those of metal carbides, silicides and germanides. Some metal phosphides are very useful semiconductors, while others shew superconduction or a variety of magnetic properties. Light-emitting diodes (LEDs) and nanostructured materials are other modem applications (Chapter 12.19). 

Carbothermal route provides a general method for preparing crystaUine nanowires of oxides such as ZnO, Al Oj and Ga Oj, nitrides such as AIN and SijN, and carbides such as SiC [3], The set-up employed for the synthesis of oxide nanomaterials is shown in Figure 3.1. The method has enabled the synthesis of crystalhne nanowires of both silica and sihcon. In the case of GaN, it has been possible to dope it with Mn, Mg and Si to bestow useful optical and magnetic properties. Carbothermal reaction involving Ga Oj powder mixed with activated carbon or carbon nanotubes carried out at 1100 °C in flowing Ar yields nanowires, nanorods as well as novel nanostructures... 

Iron metal is obtained by reduction with carbon as iron carbide. It is the least expensive and most widely used of all metals, primarily after conversion to steel, which is carbon-hardened iron. In addition to its uses in heavy construction (bridges, buildings, vehicles, armaments) [6] and because of its magnetic properties, a colloidal form of iron is extensively utilized in the manufacture of magnetic tapes and disks and other products. 

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