Boron Modifications Produced in an Induction-Coupled Argon Plasma

Abstract

Most of the small particles (50 to 100 micrometers in diameter) of microcrystalline beta-rhombohedral boron that quickly transit an argon plasma maintained within a radio-frequency induction-coupled torch emerge as better crystallized spheroids of the same crystalline form and nearly the same size as the starting material. A few crystals of each of four distinctive, well-faceted habits are formed along with the general product. Three of these types are monocrystals of the beta-rhombohedral polymorph, of the tetragonal-III modification, and of an unreported cubic form of boron. Specimens of the fourth type are polycrystals of another unreported form of boron, apparently consisting of many hexagonal platelets stacked in an imprecise fashion.

Boron: Elementary Challenge for Experimenters and Theoreticians

“…[1,110] t-II is also said to have been synthesized by sprinkling finely crushed boron into an argon plasma. [113] Since it has not been possible to reproduce the synthesis of t-II in the form of single crystals and hence its structure determination since 1978, slight doubts about the existence of this modification are justified. According to theoretical calculations, there might be a range over which t-II exists: Hayami and Otani recently published DFT studies on t-I [93] and t-II [114] which suggested that t-I and t-II can be more stable than a-B and b-B if the surface energy is taken into account in the calculations.…”

Bor – elementare Herausforderung für Experimentatoren und Theoretiker

“…[1,110] Außerdem soll t-II durch Einstreuen von fein zerteiltem Bor in ein Argon-Plasma erhalten worden sein. [113] Allerdings ist auch die Synthese von t-II in Form von Einkristallen und die Strukturbestimmung seit 1978 nicht wieder gelungen, sodass auch bei dieser Modifikation Zweifel an der Existenz angemeldet werden könnten. Theoretischen Untersuchungen zufolge soll diese Phase jedoch einen Existenzbereich aufweisen: Kürzlich publizierten Hayami und Otani DFT-Studien zu t-I [93] und t-II, [114] wonach t-I und t-II durchaus stabiler als a-B und b-B sein können, wenn man bei den Rechnungen die Oberflächenenergie berücksichtigt.…”

Mound Laboratory activities for the Division of Physical Research: July-- December 1973

“…Approximately 100 liters of waste solution, containing •an estimated 65 g of 234 U; has been concentrated to a volume of eight lit! :!rS wi~h an initial separation from 2 ;bPu and is ready for preparation as feed to the intermediate.purification step.…”

“…The separation of the two chlorine isotopes, • 3 5 Cl and 3.7Cl, was measured as a f1.1nr.t:ion of time. • Column parameters were derived from the data by fitting to the solution of the differential equation describing the transient performance of the column: ' (2) where w1 is the mass fraction of component 1, t is the time, 11 is the holdup per unit length, and z is the vertical coordinate. The quantities H and K are the initial transport coefficient.…”