Pure anhydrous cerium tetrafluoride is best prepared by fluorinating cerium dioxide at 350-500�. A monohydrate can be obtained from aqueous solution in a variety of ways, but it cannot be dehydrated without decomposition. It loses water "zeolitically" in vacuum, showing relatively small changes in lattice parameters for loss of 70% of its water content. Thereafter the lattice collapses, forming well-crystallized cerium trifluoride and poorly crystallized "anhydrous" cerium tetrafluoride. The refractive indices of anhydrous monoclinic cerium tetrafluoride have been measured and its fluorine dissociation pressure at 500� shown to be less than 0.5 mm. At higher temperatures the tetrafluoride sublimes incongruently, and at 835-841� it melts with extensive decomposition into a fluorine-poor liquid and a fluorine-rich vapour. Cerium tetrafluoride is easily reduced to the trifluoride by ammonia and by water vapour at low temperatures. At higher temperatures it is quantitatively converted by water vapour to cerium dioxide and hydrogen fluoride. When heated with cerium dioxide it is reduced to the trifluoride with liberation of oxygen.
Methods have been developed for measuring several of the physical properties of pure, freshly deposited carbide-iodide thorium over a range of temperatures without exposing the metal to atmospheric or other contamination. The allotropic transition of such material has been located at 1325 ~ _ 10~ the transition from fcc thorium to bcc thorium being complete at 1335~ in less than 1 min. New values are given for the electrical resistivity and total emissivity of thorium, these properties being markedly influenced by impurities in materials used by previous investigators. The morphology of the deposits has been studied and related to the composition and physical properties of the metal.
The compound a-K5ThF, has not previously been described. The compound K,ThF, is stable only a t high temperatures and has been shown to disproportionate a t lower temperatures into a mixture of P-K,ThF, and P-K,ThF,. Discordant views in the literature as to the formula of the compound of highest thorium fluoride content have been discussed, and the formula KTh,F,, for this compound confirmed. Partial solid solution has been shown to occur between KTh,F,, and ThF,. Optical properties have been recorded for the majority of the compounds listed.Systematic precipitation studies in the systems KF-Th(NO,),-H,O and KN0,-Th(NO,),-HF-H,O have shown that cationic complexes of thorium and fluorine strongly influence the composition of the precipitated potassium thorium fluorides. The hydrated compounds a-K,ThF,,nH,O, KTh,F,,nH,O, and ThF,,nH,O have been isolated from solution, but the compound KThF,,nH,O could not be isolated in a substantially pure state. Lattice water in the precipitated phases can be removed a t 300" without appreciable loss of fluorine.THE preparation of hydrated potassium thorium fluorides approximating in composition to K,ThF,, KThF, (probably a mixture of K,ThF, and KTh,F9), and KTh,F, (Rosenheim, Samper and Davidsohn, 2. autorg. Chem., 1903, 35, 424) suggests a considerable degree of complexity for the binary system KF-ThF,. Ample confirmation of this complexity was obtained from preliminary studies of the system and from the results of Dergunov and
A process is described for the separation of rare earth clcments in monazite into the following products : (a) cerium group hydroxides containing thorium hydroxide, (b) crude thorium osalate. Quantitative aspects of the various methods used to accomplish the separations have been investigated. The process is suitable for large scale operation.
Wylie : Extraction of Ceric Nitrate by Solvents. Solvents. Extraction of Ceric Nitrate by
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.