Whole crystal glass

If soda is replaced by potassium carbonate in glass manufacture and lead oxide is added, the light refraction properties of the glass are improved. The whole crystal glass contains at least 24% lead oxide, while the semi-crystal glass has at least 10% in all of lead, potassium and zinc oxides. Some characteristic physical properties of the different glass types are shown in Table 43.5. 

For whole crystal glass no alternative seems to be possible as the international quality systems specify a lead oxide content of 24% or more. Until these specifications are changed, the manufacture of glass with high lead levels will continue. 

The temperature dependence of the FE and glassy volume fractions was determined for the four different compositions mentioned above (Fig. 10). Whereas D-RADP-0.20 exhibits a quasi-continuous sequence of local PE-FE phase transitions with a coexistence range of about 20 K and a pure FE phase state throughout the whole crystal below 135 K [17], in D-RADP-0.25 part of the crystal remains in the PE or glass state, respectively, down to very low temperatures. This is also observed in D-RADP-0.30, while in D-RADP-0.35 (not shown) no FE polarization could be observed at all. 

A crystal is never a perfect sphere, it has some geometric shape. As it rotates in the X-ray beam, different volumes of the whole crystal may be exposed. As a consequence hki will not be equal to I-h-k-i as we supposed. The same effect is produced by absorption because the diffracted X-rays must pass through different volumes of the crystal, or different volumes of the glass capillary or solvent, liquid, or ice, that surrounds the crystal. 

In their study of the Laacher See eruption. Bourdon et al. (1994) obtained an isochron from their data on phonolitic pumice glasses (probably with U/Th ratios similar to those of the whole rocks) and glasses from cumulate nodules. The fractionation of U/Th ratios is attributed in that case to the crystallization of accessory U and Th-enriched phases such as sphene and apatite. The age of 14.3 6.5 ka is similar to the ages deduced from mineral isochrons (see section 3.5) and to the eruption age of 12.5 0.5 ka (Fig. 7b). Thus differentiation within the phonolitic magma occurred shortly before eruption. 

Most of the solid-state lasers employ as active material crystals or glasses doped with rare-earth or actinide ions, because these ions exhibit a large number of relatively sharp fluorescent lines, covering the whole visible and near-infrared spectrum 380) search for new laser materials and investigations of the characteristics of laser emission at different temperatures of the active material and with various pump sources have improved knowledge about the solid state spectra and radiationless transitions in laser media 38i). 

Into a glass tube was introduced 2-/erf-butylsulfanylacrylonitrile (21 1.41 g, 0.01 mol) and a few crystals of hydroquinone. The tube was then connected to a vessel containing chlorotrifluoroethene (CFTE) (1.7 g, 0.015 mol) which was distilled into it by cooling to — 78 °C. The tube was then sealed under vacuum, inserted into a metal tube, and the whole was heated in an oil bath for 8 h at 120°C. Caution the ampule may explode if not properly sealed. The tube was cooled in liquid N2 and opened. Excess CFTE was left... 

Boil six ounces of finely-bruised Aleppo galls In six pints of water then add four ounces of clean and well crystallized sulphate of iron, and four ounces of gum-arabic. Keep the whole in a wooden or glass vessel, occasionally shaken. In two months, strain, and pour off the ink into glass bottles.—Braude. 

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