Purity Chemicals Research Articles

Parkinsonite, (Pb,Mo, □)8O8Cl2, a new mineral from Merehead Quarry, Somerset

AbstractParkinsonite, ideally (Pb,Mo,□)8O8Cl2, is a new mineral from the Merehead Quarry, Cranmore, Somerset, England. It occurs as compact clusters or patches of red to purplish red bladed crystals, which have an adamantine lustre and a perfect {001} cleavage and occupy fractures and cavities in carbonate vughs in veins of manganese and iron oxide and hydroxide minerals. Associated minerals are mendipite, diaboleite, chloroxiphite, wulfenite, cerussite and hydrocerussite. Discrete crystals were not found; intergrown crystalline aggregates are the usual form of occurrence. The maximum grain size is about 300 × 100 µm, but most grains are appreciably smaller. Parkinsonite was synthesized using high purity chemicals. The measured density of the synthetic material is 7.32 g/cm3; the calculated density is 7.39 g/cm3, the difference being due to minor impurity and slight porosity in the synthetic sample. Parkinsonite is translucent. Reflectance spectra were obtained in air and in oil. Refractive indices calculated from these (at 589 nm) are for Ro, 2.58, and Re', 2.42, i.e. uniaxial negative. VHN50 is 113–133 from which the calculated Mobs hardness is 2–2.5.X-ray studies show that parkinsonite is tetragonal with space group I4/mmm, I4̄2m, I4̄m2, I4/mm, or I422 and a 3.9922(3), c 22.514(2) Å. It has a cell volume of 358.82(5) Å3 with Z = 1. The strongest six lines of the X-ray powder diffraction pattern are [d in Å (I) (hkl)] 2.823, 2.813(100) (110,008); 5.63(85) (004); 2.251(33) (116, 0.0.10); 2.988(27) (105); 3.750(15) (006); 1.994(11) (200,118). Averaged electron microprobe analyses give the empirical formula Pb6.34Mo0.89□0.77O8.02Cl1.98 on the basis of 10 atoms [O + Cl]. The name is for Reginald F. D. Parkinson, mineral collector of Somerset, UK, who first found the mineral.

In-Line Pretreatment Method for Flow Injection Analysis of Total Phosphorus and Nitrogen Impurities in Hydrogen Peroxide Solution

Controlling various impurities below their tolerable limits is frequently required for high purity chemicals to be used in the semiconductor industry. We have developed an in-line pretreatment device which can be coupled with the flow injection analysis (FIA) system developed for simultaneous determination of total phosphorus (TP) and total nitrogen (TN) in water

Electronic Materials: Problems and Prospects in India

Semiconductor devices require the use of electronic grade (high purity) chemicals during processing and manufacture. With ever-increasing requirements of these devices in a variety of applications, the demand for high purity chemicals is also increasing. This aspect is briefly reviewed in this paper. Silicon is a widely used semiconductor in electronic industry. The author has also shared his own experience in developing a process for semiconductor grade silicon at Indian Institute of Science. Briefly, the efforts to grow Amorphous silicon have also been mentioned.

High purity chemicals in semicon production: K. G. Clark, E. M. Juleff and S. Fawcett Electron. Prod., p.43 (April 1977)

High purity chemicals in semicon production: K. G. Clark, E. M. Juleff and S. Fawcett Electron. Prod., p.43 (April 1977)

Analysis of high purity chemicals: examination and improvement of the residue after evaporation test for solvents

Analysis of high purity chemicals: examination and improvement of the residue after evaporation test for solvents

High purity chemicals and resists : Alan J. Jertens. Proc. Internepcon. (Microelectron.) p. 83 (Oct. 19–21, 1976)

High purity chemicals and resists : Alan J. Jertens. Proc. Internepcon. (Microelectron.) p. 83 (Oct. 19–21, 1976)

High purity chemicals in semicon production : Kenneth G. Clark, E. Malcolm Juleff, and Stephen Fawcett. Electron. Prod. p. 43 (April 1977)

High purity chemicals in semicon production : Kenneth G. Clark, E. Malcolm Juleff, and Stephen Fawcett. Electron. Prod. p. 43 (April 1977)

Practical analysis of high purity chemicals—V: Precision silver chloride gravimetry

A reasonably simple gravimetric silver chloride procedure with fairly wide tolerance in conditions is presented in full detail with all critical steps and precautions delineated. The procedure allows the precision determination of chloride by analysts having limited expertise with exacting gravimetric methods, and can be performed with equipment common to nearly all laboratories and without dependence on a standard substance. The elapsed and actual working times for the assessment of a solid sample in triplicate are 65 and 10–12 hr respectively. The application of the procedure to the assay of some highpurity chloride salts and to the standardization of hydrochloric acid solutions is described.

The mechanism of the decomposition of alkaline permanganate solutions

The decomposition of permanganate in alkaline solutions which yields manganate(VI) and oxygen has been shown to be a trace-catalyzed reaction, the rate of which depends on the minute amounts of nickel and cobalt ions present in the solution. The catalyzed reaction has been studied using high purity chemicals and a new reaction mechanism is suggested. It is shown, that free hydroxyl radical, which was generally believed to be a reaction intermediate does not take part in the reaction mechanism.

The Quantitative Analysis of Non-Olefinic Gasolines

A previous method described the application of gas chromatography to the qualitative analysis of all types of gasoline. This method has now been extended and developed to enable non-olefinic gasolines to be analysed on a quantitative basis. It is particularly suitable for gasolines blended from straight-run and catalytically-reformed components, but products from other refinery processes can be similarly analysed.A number of paraffins, naphthenic and aromatic hydrocarbons were selected as being typical gasoline hydrocarbons, and calibration curves were obtained. It was found that all these curves could be reduced to a general equation, the curve for any individual hydrocarbon being obtained by inserting a specific constant. This, therefore, enabled the calibration curve for any other hydrocarbon to be constructed by simply determining any one point on that curve.For those hydrocarbons which were not available as high purity chemicals, values for the constant were extrapolated from the experimentally determined values of the available hydrocarbons. Hence calibration curves were drawn for these hydrocarbons and those which were not otherwise available. The data so obtained is applied in this paper to the quantitative analysis of three commercial gasolines.The gas liquid chromatography apparatus employed in this study consists of a programme heated column with a non-polar stationary phase, and a flame ionisation detector.