The structure of V4Al23

Abstract

The crystal structure of the intermetallic compound V4~L123 has been determined. The space-group symmetry was found to be D~h-P63/mmc, and precision lattice parameters were measured as a = 7.6928 ~, c = 17.040 A. The compound is structurally related to Co2A15, Fe3NiAll0, and MnaSiA] 9. The compound shows a pronounced, but imperfect, layering. Zone boundaries are prominent. Abnormally short A1-V bond distances were found.

New insights on the crystalline forms in binary systems of n-alkanes: Characterization of the solid ordered phases in the phase diagram tricosane + pentacosane

“…However, we are interested in having the diffractogram of the orthorhombic phase alone. Smith 30 found that pure even alkanes above C 26 normally crystallize as monoclinic at room temperature, but if impurities (neighboring homologues) exist, they crystallize in the orthorhombic form. We have thus prepared mixed samples of C 28 with C 26 molecules behaving like impurities (in fact, we have studied the binary system C 26 1 C 28 which will be the subject, as said, in the introduction of another paper).…”

“…The study of binary phase diagrams (temperature versus composition) has revealed a complex structural behavior of the mixed samples [28][29][30][31][32][33][34][35][36][37][38][39][40][41] where other forms than those seen in the components are observed and which are stabilized by mixing. The earliest binary phase diagram showing multiple one-phase domains at low temperature (temperature domain where the ordered phases are observed) is that of Lüth et al 28 for the system C 20 -C 22 .…”

“…Polymorphism of n-alkanes (C n H 2n12 ; hereafter denoted by C n ) and determination of binary phase diagrams [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] in the alkane family have been reported on in recent years in numerous publications. The polymorphism of n-alkanes is rather well known where many solid-solid phase transitions have been observed as a function of temperature.…”

The oxidation resistance and hardness of some intermetallic compounds

“…Here we have brittle compounds of low symmetry so that prima facie All0V might (to take one example) be expected to be as hard as AIsV. However, it has been shown [7][8][9] that the compounds All0 and A16V are characterized by the persistence of a basic:, tetrahedral unit of structure. These stro~gfyf bonded A13V units arrange themselves to each other in different ways in the two compounds, the remainder of the structure in each case being 61t filled with aluminium of more "metallic" size.…”

A test for electron transfer in the intermetallic compound, V4Al23

“…The structure of the compound V4AI23 has been determined by Smith and Ray (1957). This compound was chosen for the purposes of this in vestigation for several reasons, namely, (1) it has a large, fairly complex structure and therefore several observable reflections at rela tively small diffraction angles; (2) there is little doubt as to the correctness of the structure since it has been determined independently by Brown*; (3) it is one of the few compounds of this type which appears *Brown, P. J. Cambridge, England.…”