Bismuth-stabilized

These stability changes are in accordance with the change from a non-metal to a weak metal for the Group V elements nitrogen to bismuth. 

Bismuth oeeurs mainly as bismite (a-Bi203), bismuthinite (Bi2S3) and bismutite [(Bi0)2C03] very oeeasionally it oeeurs native, in assoeiation with Pb, Ag or Co ores. The main eommereial souree of the element is as a byproduet from Pb/Zn and Cu plants, from whieh it is obtained by special processes dependent on the nature of the main product. Sulfide ores are roasted to the oxide and then reduced by iron or charcoal. Because of its low mp, very low solubiUty in Fe, and fairly high oxidative stability in air, Bi can be melted and cast (like Pb) in iron and steel vessels. Like Sb, the metal is too brittle to roll, draw, or extrude at room temperature, but above 225°C Bi can be worked quite well. 

Beta radiation Electron emission from unstable nuclei, 26,30,528 Binary molecular compound, 41-42,190 Binding energy Energy equivalent of the mass defect measure of nuclear stability, 522,523 Bismuth (m) sulfide, 540 Blassie, Michael, 629 Blind staggers, 574 Blister copper, 539 Blood alcohol concentrations, 43t Body-centered cubic cell (BCC) A cubic unit cell with an atom at each comer and one at the center, 246 Bohrmodd Model of the hydrogen atom... 

When Z gets big enough, no number of neutrons is enough to stabilize the nucleus. Notice in Figure 2-20 that there are no stable nuclei above bismuth, Z — 83. Some elements with higher Z are found on Earth, notably radium (Z = 88), thorium (Z = 90), and uranium (Z = 92), but all such elements are unstable and eventually disintegrate into nuclei with Z < 83. Consequently, the set of stable nuclei, those that make up the world of normal chemistry and provide the material for all terrestrial chemical reactions, is a small subset of all possible nuclei. 

A study was made of the comparative stabilities at various exposures of an upset stomach remedy suspension. This product consisted of a dispersion of bismuth subsalicylate and phenylsalicylate in an aqueous system. Methyl-cellulose and magnesium aluminum silicate were selected as the suspending agents, because the presence of polyvalent metallic ions precluded the use of hydrocolloids affected by these ions. In addition, it was found that methyl-cellulose contributed a demulcent effect. The viscosity, as well as the suspension characteristics of the combination of protective colloids used, was of a synergistic nature. These colloids formed a thixotropic system. The thixotropy undoubtedly aids in stabilizing this system. In order to make this product palatable and impart elegance, color and flavor were added. Sample 1 (with protective colloids) showed no separation, while sample 2 (without... 

The origin of chemical elements has been explained by various nuclear synthesis routes, such as hydrogen or helium burning, and a-, e-, s-, r-, p- and x-processes. "Tc is believed to be synthesized by the s (slow)-process in stars. This process involves successive neutron capture and / decay at relatively low neutron densities neutron capture rates in this process are slow as compared to /1-decay rates. The nuclides near the -stability line are formed from the iron group to bismuth. 

There are many organometallic compounds of arsenic, antimony, and bismuth known that constitute series having chemical properties that differ markedly. These compounds generally decrease in stability in the order As > Sb > Bi, which agrees with the increasing difference in size of the atoms and carbon atoms. Arsenic compounds include both aliphatic derivatives and heterocycles such as arsabenzene,... 

Metal Compound Mixtures - Part III. A Comparison of Behaviors of Antimony Trioxide and Bismuth Compounds," Polym. Degradation and Stability, d, 367 (1983). ... 

The favorable bismuth-sulfur bond translates into thermal and hydrolytic stability for the thiolates of bismuth, which are currently more numerous than the alkoxide derivatives (Table II). Various monomeric trithiolates have been identified, and most adopt predictable structural formulas, although the solid-state structures reveal interesting intermolecular and intramolecular interactions. 

See Table XII and Chart 5.) The stability of the thiolate-bismuth bond has allowed for the assessment of interactions between bismuth... 

Alkoxide bridged dimers are observed for Bi(02CCH3)2(bdmap) (H20)o,5 (237) and Bi2(Hdpmd)2(02CCF3)4 (thf)2 (238). The stability of the compounds is accredited to the coordinative saturation of bismuth... 

Four solid oxide electrolyte systems have been studied in detail and used as oxygen sensors. These are based on the oxides zirconia, thoria, ceria and bismuth oxide. In all of these oxides a high oxide ion conductivity could be obtained by the dissolution of aliovalent cations, accompanied by the introduction of oxide ion vacancies. The addition of CaO or Y2O3 to zirconia not only increases the electrical conductivity, but also stabilizes the fluorite structure, which is unstable with respect to the tetragonal structure at temperatures below 1660 K. The tetragonal structure transforms to the low temperature monoclinic structure below about 1400 K and it is because of this transformation that the pure oxide is mechanically unstable, and usually shatters on cooling. The addition of CaO stabilizes the fluorite structure at all temperatures, and because this removes the mechanical instability the material is described as stabilized zirconia (Figure 7.2). 

FIGURE 1.2 Composition dependence of conductivity for yttria-stabilized zirconia (YSZ) measured at 1000°C [7], yttria-doped bismuth oxide (YDB) at 600°C [6], and yttria-doped ceria (YDC) at 700°C [8],... 

Figure 10.2 The radioactive stability of the elements. The x axis is proton number (up to Z = 83, bismuth), the y axis the neutron number (N). Stable isotopes are shown in black and radioactive isotopes in grey, indicating the relative excess of radioactive isotopes over stable isotopes in nature, and the fact that as proton number increases, the neutron number has to increase faster to maintain stability. The basic data for this figure are given in Appendix VI.

Bonnemann, H. etal., Selective oxidation of glucose on bismuth-promoted Pd-Pt/C catalysts prepared from N(Oct)4Cl-stabilized Pd-Pt colloids, lnorg. Chim. Acta., 270, 95, 1998. 

A second class of membranes are described as dense membranes. They may consist of thin plates of metals (Pd and its alloys, Ag and some alloys) or oxides (stabilized zirconia or bismuth oxides, cerates). These membranes are permeable to atomic (for metals) or ionic (for oxides) forms of hydrogen or oxygen and have been studied, especially, in conjunction with chemical... 

Abstract Several bismuth-catalyzed synthetic reactions, which proceed well in aqueous media, are discussed. Due to increasing demand of water as a solvent in organic synthesis, catalysts that can be used in aqueous media are becoming more and more important. Although bismuth Lewis acids are not very stable in water, it has been revealed that they can be stabilized by basic ligands. Chiral amine and related basic ligands combined with bismuth Lewis acids are particularly useful in asymmetric catalysis in aqueous media. On the other hand, bismuth hydroxide is stable and works as an efficient catalyst for carbon-carbon bond-forming reactions in water. 

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