Zur Kenntnis der Chrom(II)‐Salze und des Chrom(II)‐oxyds, II

Abstract

Die in der älteren Literatur als Chrom(II)‐oxyd beschriebenen, durch Oxydation von Chromamalgam erhältlichen Produkte sind röntgenamorph, in ihrer Zusammensetzung undefiniert und enthalten stets noch reichlich Quecksilber. Als Chrom(II)‐oxyd sind sie aus der Literatur zu streichen. — Die thermische Zersetzung von Chrom(II)‐oxalat und Chrom(II)‐formiat i. Hochvak. bei Temperaturen bis 800° führt zu Rückständen der Zusammensetzung CrO1.5–1.32. Vorsichtige Trocknung von Cr(OH)2 ergibt ein Produkt der Zusammensetzung CrO1.08·0.33 H2O, das bei weiterem Erwärmen nur noch Wasserstoff abgibt. Chrom(II)‐oxyd entsteht jedoch, wenn man Chromhexacarbonyl bei 250 bis 550° i. Hochvak. zersetzt. Das Produkt ist in kochender konz. Salzsäure oder heißer konz. Schwefelsäure unlöslich und zeigt im Pulverdiagramm nur die Linien des Steinsalzgitters mit einer Identitätsperiode von 4.12 Å, die nahezu mit jener des ebenfalls kubischen CrN übereinstimmt. Oberhalb von 700° zersetzt sich die Substanz rasch unter Disproportionierung.

Transformations in CrFeCoNiCu High Entropy Alloy Thin Films during In-Situ Annealing in TEM

“…The composition measured in the whole area in Figure 8 demonstrates that the composition of the original HEA phase on average was basically preserved in the film. These results lead to the conclusion that the crystals, which remained in the voids have a possible composition Cr 4-x M x O 4 (M can be Co, Fe, Ni or Cu) corresponding to four molecules in the FCC unit cell of either CrO [25] or a HEA-oxide [26] type phase.…”

“…The composition measured in the whole area in Figure 8 demonstrates that the composition of the original HEA phase on average was basically preserved in the film. These results lead to the conclusion that the crystals, which remained in the voids have a possible composition Cr4-xMxO4 (M can be Co, Fe, Ni or Cu) corresponding to four molecules in the FCC unit cell of either CrO [25] or a HEA-oxide [26] Local EDS measurement of the composition inside the "void" proves that these areas were dominated by Cr accompanied by only a little amount of the remaining HEA metal components (area #1 in Figure 8 and in Table 3). Areas #2 and #3 in Figure 8 and in Table 3 indicate compositional fluctuation on the tens of nm scale implying that the redistribution of components is going on.…”

“…According to the phase analysis of the diffraction pattern recorded at 700 • C ( Figure 3b) the L12 simple cubic phase reflections of the same lattice parameter as the host HEA FCC phase (a = 0.360 nm) were identified besides of the BCC phase (a = 0.294 nm). Moreover, another small grain size FCC phase of a = 0.420 nm was present, which could be identified as a complex oxide phase [25].…”

Transformations in CoCrCuFeNi MPEA thin films during in-situ annealing in TEM

“…The composition measured in the whole area in Figure 4.9 demonstrates that the composition of the original MPEA phase on average was basically preserved in the film. These results lead to the conclusion that the crystals, which remained in the voids have a possible composition Cr 4-x M x O 4 (M can be Co, Fe, Ni or Cu) corresponding to four molecules in the FCC unit cell of either CrO [127] or a MPEA-oxide [108] type phase.…”