Chemischer Transport ternärer Indiummolybdate

Abstract

Chemical Vapor Transport of Ternary Indium MolybdatesAn isothermal section of the phase diagram of the system In/Mo/O at 1273 K was established by isothermal equilibration and XRD analyses of quenched samples. The chemical vapor transport of In2Mo3O12 was investigated in dependence on mean transport temperature (823 K to 1123 K) and amount of transport agent (Cl2 or Br2). The observed transport behaviour is compared with results of thermodynamical calculations and the influence of mean temperature, transport agent and moisture contents is described in detail. Single crystals of the metal rich compound InMo4O6 were grown by chemical vapor transport in a temperature gradient 1273 K to 1173 K using H2O as transport agent. The gaseous compound In2MoO4(g) accounts for the chemical vapor transport of molybdenium compounds in the metal rich part of the ternary phase diagram In/Mo/O.

Thermal stability of In2(MoO4)3 and phase equilibria in the MoO3–In2O3 system

“…The above results have undoubtedly proven that the compound studied does not melt at 1230°C as suggested by the authors of [10], but it undergoes a thermal decomposition in the solid phase to In 2 O 3 with sublimation of MoO 3 . In the air atmosphere, this decomposition begins with a low rate even at 935°C.…”

“…1) revealed two endothermic effects of which the first (a small one) started at 335°C, while the second started at 1125°C. On the basis of the literature data [9,10], the first effect starting at 335°C was assigned to the polymorphous transition of the regular indium(III) molybdate(VI) to the orthorhombic crystal form of this compound. The temperature of this transition is consistent with the values reported by other authors [9].…”

“…MoO 3 , In 2 O 3 and In 2 (MoO 4 ) 3 formed as a result of a reaction between the former two, are components of active and selective catalysts of different processes of oxidation of organic compounds, e.g. methanol to formaldehyde, propene to acrylaldehyde or acrylic acid, or benzene to maleic anhydride [8][9][10]. These oxides have been used in semiconducting sensors for detection of oxidating gases O 3 and NO 2 [11].…”

“…It is known that at *340°C this compound (In 2 (MoO 4 ) 3 ) undergoes a polymorphous transition from the variety of regular structure (C-In 2 (MoO 4 ) 3 , a = 13.34 ± 0.07 Å ) [9] to the variety of orthorhombic structure (R-In 2 (MoO 4 ) 3 , a = 9.447 Å , b = 9.597 Å , c = 13.29 Å ) [10]. The authors of the study [10] gave the melting point of this compound as 1230°C, however, with no information on the type of the melting process, i.e. whether it is congruent or incongruent.…”

Thermochemistry and Chemical Vapor Transport of In2M3O12 (M = Mo, W)

“…With these data now available, we use thermodynamic modelling for a detailed analysis of the transport behavior of compounds In 2 M 3 O 12 ( M = Mo, W) with transport agent chlorine. The chemical vapor transport of In 2 Mo 3 O 12 using chlorine or bromine as transport agent was investigated before 5. Modeling in the earlier work5 was carried out with estimated thermodynamic data for In 2 Mo 3 O 12 only.…”