16229-40-6Relevant articles and documents
Dielectric properties of low-firing Bi2Mo2O 9 thick films screen printed on Al foils and alumina substrates
Liu, Weihong,Wang, Hong,Zhou, Di,Li, Kecheng
, p. 2202 - 2206 (2010/11/19)
Low-firing Bi2Mo2O9 thick films with a thickness of 15-20 μm were screen printed on Al foils and alumina substrates by screen-printing technology. The phase evolution, morphologies, and dielectric properties of the thick films were investigated. The thick films showed a pure Bi2Mo2O9 phase at temperatures below 610°C. A mixture of Bi2MoO6, Bi2Mo3O 12, and Bi2Mo2O9 phases was found in the thick films sintered at 610°C and higher temperatures. The Bi 2Mo2O9 thick films on Al foils sintered at 645°C showed excellent dielectric properties with a relative permittivity of 38 and a dielectric loss of 0.7% at 5 MHz. At the microwave frequency range from 5 to 19 GHz, the Bi2Mo2O9 thick films on alumina substrates sintered at 645°C had a relative permittivity of ～35 and Q × f of ～12 500 GHz. It indicates that the Bi2Mo 2O9 composition as potentially useful for low-temperature cofired ceramic using Al electrode.
Reactivity and properties of [-O-BiIII...O=Mo-]n chains
Roggan, Stefan,Limberg, Christian,Ziemer, Burkhard,Siemons, Maike,Simon, Ulrich
, p. 9020 - 9031 (2008/10/09)
A coordination polymer [Cp*(O)2Mo-O-Bi(o-tolyl) 2]n, II, containing Mo-O-Bi and Mo=O...Bi moieties was investigated with respect to its behavior in contact with OH- and Cp2MoH2 and as potential single source precursor in the polyol method. It turned out that hydroxide as a base breaks up the polymer to yield Cp*MoO3- and (o-tolyl)2BiOH. The latter polymerizes to give the coordination polymer [(o-tolyl) 2BiOH]n, 1. Alternatively, 1 can be prepared by reacting [(o-tolyl)2Bi(hmpa)2]SO3CF3 with NBu4OH/H20 in thf/water. If, however, NBu 4OH/MeOH is used in dichloromethane as the solvent, the (o-tolyl)2BiOH formed intermediately undergoes methanolysis, and finally, [(o-tolyl)2BiOMe]n, 3, is isolated. Although 1 and 3 are very similar compounds, their crystal structures differ significantly: while the structure of 1 is dominated by secondary bonding leading to seesaw-type coordination geometries around the Bi centers, the Bi atoms in 3 are coordinated in a distorted tetrahedral fashion, and secondary bonding plays only a minor role. If 1 is dissolved in a nonpolar, nonprotic solvent, condensation reactions occur immediately leading to [(otolyl) 2BiOBi(o-tolyl)2], 2, which can be obtained on a preparative scale this way. Compound 3 which can be prepared in good yields may prove to be a useful starting material in bismuth chemistry. Here, it was shown to react with molybdocene dihydrides to provide stable Bi-substituted molybdocene monohydrides [RCp2-Mo(H)(Bi(o-tolyl) 2)] (R = Me 4, R = H 5); compounds of that type were identified in solution before but had so far eluded isolation. Compound 4, whose crystal structure is discussed, also forms when II is treated with methylated molybdocene dihydride. This obviously leads to the formation of Mo-Bi bonds (→ 4), as well as Mo-OH units, which undergo condensation reactions leading to Mo-O-Mo moieties (i.e., [Cp*2Mo2O5] is formed as a byproduct). The use of II as precursor in the polyol method successfully led to bismuthmolybdate nanoparticles (accompanied by crystallites); however, no single phase is obtained, but biphasic materials consisting of Bi2Mo2O9 and Bi 2MoO6, whose ratio can be determined by the choice of the hydrolyzing reagent, are formed instead. One of these materials proved to be capable of sensing EtOH selectively at elevated temperatures.
