Glasses containing transition metal oxides

It is interesting to note here that Mj, which is an octahedra, has two NBOs attached to the central Mo or W. We should expect for reasons of coulombic repulsion that the two NBOs are posited at the opposite comers of the octahedron. The next stage of modification does not lead to the formation of [M03/203] . Indeed it does not occur at all in a chemical sense. Only [M04] is formed as a result of stmctural conversion of M2. This is because the increased O ion activity brought about by the higher concentration of K2O, induces a stmctural rearrangement in [MO4/2O2] as 

The formation of discrete M04 (s M3) shows up in the IR spectra and manifests in various properties of these glasses. Corresponding changes occur when M-O-P linkages are modified leading to the formation of Q3, 

If PbO is added instead of an alkali oxide to the molybdophosphate or tunstophosphate glasses, the modification becomes even more 

Formation of Mo is a consequence of a small degree oxygen loss during the preparation of these glasses. In the presence of modifier oxides, oxygen loss is suppressed and concentration is of Mo is also suppressed. This is because of increased O ion activity in the melt. The concentration 

Transition metal (TM) ions can be readily incorporated particularly into phosphate glasses. Since TM ions give rise to characteristic spectra in the region of near IR to near UV, their characterization is relatively easy. An example is the study of a series of glasses having chemical compositions of NASICONs. NASICON is an acronym for sodium superionic conductors of the general formula A B2(P04)3, where B is generally a TM ion or elements like Zr, Ge, Sn, etc. (or their combination) and A is an alkali metal, whose number n in the formula is dependent on the 

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Franz, H. "Infrared Absorption of Molten Soda-Lime-Silica Glasses Containing Transition Metal Oxides." International Congress on Glass, Science and Technology 9, no. 1 (1971) 243-60. 

Solution Phase. Adsorption experiments were done in aqueous solutions containing 1.093 X 10" M NaHC03 plus 9.156 X lO M NaCl (0.02 I buffer) (some buffers were prepared with 1% less NaCl) and 1.516 X lo w NaHC03 plus 2.941 X 10 W NaCl (0.305 I buffer) (twice physiological ionic strength) equilibrated with 5% CO2 in air at 15° it 2°C. Buffer compositions were determined by chemical titration and calculations that included both activity coeflGcients and complexation. Buffer solutions were prepared with ddd H2O, sterilized by 0.22 /xm Milli-pore filtration, and stored in borosilicate glass vessels. For transition metal oxide experiments, buffers were pre-equilibrated with solids for at least... 

The earliest glasses used by man were found in nature. The ease of formation of sharp edges on obsidians, for example, allowed the production of knives, arrow heads, and other cutting tools. These naturally occurring glasses, which result from the cooling of molten rock, or lava, contain a wide variety of components, including alkali, alkaline earths, and transition metal oxides. In every case, however, silica is found to be the major constituent of these materials. 

Structural Insight into Transition Metal Oxide Containing Glasses by Molecular Dynamic Simulations... 

The glass fiber based catalysts containing transition metals in highly dispersed state (mostly, Pt and Pd) were tested in many catalytic reactions, such as deep oxidation of saturated hydrocarbons [1], SO2 oxidation [3], deNOx [8], selective hydrogenation of acetylene feedstock [2 ] etc. Despite of extremely low content of noble metals the GFCs showed high activity and thermal stability, low ignition temperature. 

Colored or stained glass has been made for thousands of years, first by Egyptians and later by Romans. Color is typically introduced by addition of transition metals and oxides. Table 12.5 contains selected inorganic colorants and the resulting colors. Because of the high... 

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