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Zu den Phasenverhältnissen im System V/Nb/O, III Die Koexistenzbeziehungen der Mischkristallreihe V1_J t-NbJC 02 zu den binären und ternären Phasen derSubsysteme V 0 2/N b 02/V20 3 und V 0 2/N b 0 2/V20 5/Nb20 5 The Phase Relations in the System V /N b/O , III C oexistance R elations o f M ixed C rystals V j_ xN bxOT to the Binary and Ternary Phases o f Subsystem s V 0 2/N b 0 2/V 20 3 and V 0 2/N b 0 2/V 20 5/N b 20 5 F. von Woedtke, L. KirstenMixed crystals V|_^NbA0 2 exist about the whole area of quasibinary line V 0 2-N b02. The phase relations between these compositions V 0 2-N b 02 and the binary and ternary phases of the described subsystems were cleared using chemical transport reactions (CTR) and solid state reactions. A more precise phase diagram of the ternary system V/Nb/O is given for the temperature range of 900 -1000°C.

The observation of reductive decomposition with SEC-current-time-temperature curves on the binary line V2O5-Nb2O5 is a useful method to determine qualitatively and quantitatively (“quasi in situ”) the known ternary coexistence regions. By reduction of VO2 the Magneli-Phases VnO2n-1 are generated. The method is generally applicable and allows rapid information by reductive decompositon or oxidative formation in coexistence regions.The conditions of decomposition can be optimized for a given system. Slow solid-gas equilibria are not detectable by this method.

The Phase Relations in the System V/Nb/O. Part 4. Solid Electrolytic Coulometry (SEC) as a Method to Investigate Ternary Systems: V/Nb/O. -The observation of reductive decomposition with SEC-current-time curves on the binary line V 2 O 5 -Nb 2 O 5 is a useful method to qualitatively and quantitatively determine the known ternary coexistence regions. The Magneli phases VnO 2n−1 are generated by reduction of VO 2 . Slow solid-gas equilibria are not detectable by this method. -(KIRSTEN, L.; VON WOEDTKE, F.; OPPERMANN, H.; Z. Naturforsch., B: Chem. Sci. 54 (1999) 1, 123-130; Inst. Anorg.