I. The preparation and configuration of levorotatory 4,5-dimethly-1,3-dioxolane. II. Studies of color centers in alkali halide crystals. III. A structural investigation of the strontium-zinc system
NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. I. The configuration of the formal of [...]-2,3-butanediol has been established unequivocally by reactions of the diol under basic conditions with methylene iodide, methylene chloride...
| Summary: | NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.
I. The configuration of the formal of [...]-2,3-butanediol has been established unequivocally by reactions of the diol under basic conditions with methylene iodide, methylene chloride, and chloromethyl acetate. The products are optically active, are alike, and are the same as the one obtained in the acid-catalyzed reaction of the glycol with formaldehyde.
II. The coloration of sodium chloride by white x-radiation has been separated into two distinct types. The intense color at the surface involves the creation of new anionic vacancies by longwave radiation; aggregate color centers result from optical or thermal bleaching. The less intense coloration throughout the crystal is due to the short-wave radiation; no new vacancies are created and no secondary coloration occurs. Plastic deformation does not affect the overall colorability but greatly enhances the secondary coloration effects. Tentative mechanisms for these processes are discussed.
Studies of the secondary radiative coloration, the so-called colloidal band in additively colored crystals, and the color of blue rocksalt have led to the suggestion that these color centers are members of a continuous series of F center aggregates. The possibility of a true colloidal dispersion in additively colored sodium chloride has been investigated by comparison of these crystals with sodium chloride, known to contain colloidal copper.
Crystals of sodium chloride have been grown containing heavy metal ion impurities. Spectrophotometric studies have been made of these crystals before and after radiative and additive coloration. The ultraviolet absorption bands in the uncolored crystals have been tentatively explained in terms of V centers. X-radiation and bleaching destroys some of the absorption bands and creates others.
III. An investigation of the strontium-zinc system, using x-ray diffraction techniques, has revealed four intermetallic phases. The compound SrZn13, previously reported elsewhere, has been confirmed with respect to composition and symmetry. The second phase, SrZn5, contains 24 atoms in its unit cell, is orthorhombic, and has been tentatively assigned the symmetry Pmnb. The third phase, SrZn2, is also orthorhombic, and has 12 atoms in a body centered unit cell. No single crystals of the fourth phase have been isolated, but the composition has been shown to correspond approximately to Sr3Zn2 or Sr4Zn3.
The structure of the [...] phase has been worked out in detail. It has the space group [...]-Imma, and corresponds to an orthorhombic distortion of the hexagonal magnesium boride structure.
|
|---|