[en] The puzzle of three-dimensional magnetic interactions in the structurally two-dimensional layered-oxide Na_xCoO₂ is addressed using first-principles calculations and an analysis of the exchange mechanisms. The calculations agree with recent neutron results, favoring the antiferromagnetic stacking of ferromagnetic planes. The superexchange via direct O-O hopping and through intermediate Na sp² hybrids couples each Co to its nearest and six next-nearest interplanar neighbors via equivalent paths. The individual exchange constants are rather two-dimensional, like the lattice itself, but due to multiple c-axis exchange paths, the magnetism becomes effectively three-dimensional.

[en] Interest in zirconium as a structural material for nuclear reactors has led to a research for cheaper, more convenient ways of opening up Thai zirconium ores. The most abundant domestic zirconium ore is zircon. Caustic soda was found to be effective in decomposing this ore. The content of zirconium oxide and hafnium oxide in Thai zircon were found to be 65.57+-0.18% and 1.43% respectively by X-ray fluorescence spectrometer. By using a caustic to zircon sand weight ratio of 3:2 and a furnace temperature of 550⁰C for 45 min, the zircon sand was decomposed without previous grinding. It was found that 98.62+-0.23% of the Thai zircon reacted to form water-soluble sodium silicates and water-insoluble sodium zirconates. The contents of zirconium and hafnium oxide in the zirconia sample determined by neutron activation technique were 92.14+-1.86% and 2.53+-0.30% respectively. Quality test of the zirconium crystals done by X-ray diffraction technique found that most of the zirconia crystal structure were monoclinic, some tetragonal form was also present

No abstract available

[en] Microhardness of glasses of R₂O-B₂O-SiO₂ (R=Li, Na, K, Rb, Cs, Li+Cs) systems is determined on PMT-3 device. The most fully considered is ternary sodium system, where 141 multisilicon glasses, lying in 25 sections with constant content of each components or constants ratio between them, are studied. Data on microbrittleness of glasses with SiO₂/Na₂O=4 are obtained

[en] A method of sintering a shaped green, beta-type alumina body comprising: (A) inserting said body into an open chamber prepared by exposing the interior surface of a container consisting essentially of at least about 50 weight percent of alpha-alumina and a remainder of other refractory material to a sodium oxide or sodium oxide producing environment; (B) sealing the chamber; and heating the chamber with the shaped body encapsulated therein to a temperature and for a time necessary to sinter said body to the desired density. The encapsulation chamber prepared as described above is also claimed

No abstract available

No abstract available

[en] A glass composition was developed to accommodate 30 wt % sodium oxide and resist devitrification and leaching. An in-can melting process that is compatible with a comtaminated sodium calciner developed by Argonne National Laboratory was tested both on a laboratory and on an engineering scale and found to be viable. The Liquid Metal Fast Breeder Reactor experimental program continues to produce elemental sodium contaminated with radionuclides. This material is presently in temporary storage facilities because the current criterion will not permit alkali metals to be disposed of in shallow land burials. As a first step in treatment, Argonne National Laboratory (ANL) has developed a calciner that will convert the sodium metal to an oxide. In work supported by the U.S. Department of Energy, Pacific Northwest Laboratory (PNL) is developing and demonstrating a process that is compatible with the calciner and facilities at ANL-West for incorporating sodium oxide into a glass. Glass, which normally contains sodium oxide, was chosen as the waste form because it is chemically durable and nondispersible. It is simple to produce, and the technology for incorporating nuclear wastes into glass is well developed

[en] Several procedures for preparation of the ^95mTc radiotracer following irradiation of a thin Mo target with deuterons were tested. The procedures consisting of alkaline-oxidative fusion of the irradiated target in a mixture of Na₂O₂ + NaOH and subsequent liquid-liquid extraction with 2-butanone, and acid decomposition of the target in a mixture of H₂SO₄ + HNO₃ followed by extraction chromatography with PAN-Aliquat 336 composite material appeared suitable for the given purpose. (author)

[en] Reaction between metal clusters and various reactant gases in a coexpanding nozzle led to the formation of Na₂Cl and Na₂O. These species were subjected to photoionization using a UV light source, monochromator, and mass spectrometer detection system. Appearance potentials of 95.7 and 116.7 kcal/mol were obtained for Na₂Cl and Na₂O, respectively. The appearance potential of the Na₂Cl lies between the ionization potential of the metal and the electron affinity of chlorine, while that of Na₂O is close to the ionization potential of the metal. Using these values and other literature data, energies were derived for the following bonds: Na--NaCl (19.7 kcal/mol), Na⁺₂xCl (115.5), Na₂xCl (98.9), and Na⁺₂xCl^- (127.8); Na⁺xNaO (56.8), Na⁺₂xO (94.2), Na₂xO (98.6), and Na⁺₂xO^- (177.2)