Zum Chemischen Transport im System Mg/Mo/O ‐ Experimente und Modellrechnungen

Abstract

Equilibria Equilibria E 4000On

Synthesis, Characterization, and Chemical Vapor Transport of Solid Solutions in the MgMoO4‐NiMoO4 System

“…Since the chemical vapor transport of the boundary phases NiMoO 4 8 and MgMoO 4 9 with chlorine as transport agent is well understood, thermodynamic modeling on the β‐Mg 1– x Ni x MoO 4 solid solution were conducted prior to the experiments in order to choose appropriate experimental conditions and to give predictions of the results.…”

“…The transport of MMoO 4 (M = Ni, Mg) with chlorine as transport agent can be described by the general equilibrium Equation (1):8,9 …”

“…A more detailed analysis by means of thermodynamic modeling8 revealed 1100 K for NiMoO 4 . Sink temperatures ≥ 1173 K are necessary for a detectable transport of MgMoO 4 9, on the other hand transport temperatures above 1273 K are not recommended for practical reasons (increasing reaction with the quartz wall, durability of the furnace etc.). Thus 1273 K and 1173 K were chosen as source temperature and sink temperature in a first series of experiments with β‐Mg 1– x Ni x MoO 4 solid solution.…”

“…Migration rates at deposition temperatures <823 K are too low for a detectable deposition of α‐NiMoO 4 8. The chemical vapor transport of MgMoO 4 is also well investigated 9. Because the solubility in the gas phase is lower for magnesium than for nickel, temperatures ≥ 1173 K are necessary for MgMoO 4 deposition rates greater than 0.1 mg · h –1 .…”

Chemischer Transport ternärer Oxide in den Systemen Ca/Mo/O und Sr/Mo/O

“…Während über den Chemischen Transport binärer und ternärer Magnesiumverbindungen eine Reihe von Untersuchungen bekannt sind (siehe [1,2]), ist zum Transport ternärer Calcium-und Strontiumoxide bisher sehr wenig veröffentlicht worden. Ausnahmen sind CaNb 2 O 6 [3] sowie kürzlich MWO 4 (M ϭ Ca, Sr) [4].…”