We have measured the a. c. conductivity of pure BaFz single crystals up to 1 336 K. At the higher temperatures we observed polarisation effects possibly due to a reaction of the crystal with the atmosphere in the cell. The defect energies derived from the low temperature region agree well with those obtained by Barsis and Taylor [27, 281. The effect of the high temperature phase transition on t...

Recently, the energy of all five levels of the @Xe#5d configuration of Ce in 63 different fluorides and oxides have become available. It provides values for the barycenter shift of the 5d configuration. This shift was analyzed by a model that involves the polarizability of the anion ligands, and values for the in-crystal anion polarizability were obtained. In this work, for Ce in both the oxide...

Hydrogenated amorphous silicon alloys of carbon and germanium can be deposited by glow-discharge decomposition of gaseous hydrides or fluorides. Non-plasma methods such as photochemical vapour deposition are also used and offer guidelines for understanding and improving the standard glow-discharge method. These amorphous alloys usually have poorer structural and electronic properties than pure ...

Fluorine is a highly reactive common element that does not occur in nature in the elemental state. It exists in the form of fluorides and accounts for about 0.3 g/kg of the Earth’s crust. Generally, it is found in the form of a number of minerals like fluorspar, cryolite and fluor-apatite. Fluoride has both positive and negative effects on individual health. Fluoride, in the form of fluorspar a...

A major shortcoming in olefin metathesis, a chemical process that is central to research in several branches of chemistry, is the lack of efficient methods that kinetically favor E isomers in the product distribution. Here we show that kinetically E-selective cross-metathesis reactions may be designed to generate thermodynamically disfavored alkenyl chlorides and fluorides in high yield and wit...

Fluoroform (HCF3, HFC-23) is a side product in the manufacture of polytetrafluoroethylene (Teflon). Despite its attractive properties, taming HCF3 for trifluoromethylation is quite problematic owing to its low acidity and the lability of the naked trifluoromethyl carbanion generated from HCF3. Herein we report the organic-superbase-catalyzed trifluoromethylation of ketones and arylsulfonyl fluo...

The fluorolytic sol-gel synthesis for binary metal fluorides (AlF₃, CaF₂, MgF₂) has been extended to ternary and quaternary alkaline earth metal fluorides (CaAlF₅, Ca₂AlF₇, LiMgAlF₆). The formation and crystallization of nanoscopic ternary CaAlF₅ and Ca₂AlF₇ sols in ethanol were studied by 19F liquid and solid state NMR (nuclear magnetic resonance) spectroscopy, as well as transmission electron...

This study compares the values of the critical air pollution indicators (including-sulphur dioxide, smoke, total deposited matter, gaseous fluorides, fluorides, and manganese in suspended particulates and deposited matter) measured in Sibenik for years 1989/90 when the industry was working with full capacity, and for years 1994/95 and 1995/96 when most plants were shut down due to Serbian aggre...

Significant differences inseveralcomponents of bronchoalveolar lavage fluid (BAL fluid) have previously been reported in aluminium potroom workers compared with controls. The present paper describes the long term effects in rats of one time exposure to potroom aluminium oxide without fluorides (primary alumina (PA)) or with adsorbed fluorides (secondary alumina (SA) ) on components of BAL fluid...