Auf der Suche nach neuen Materialien: Kristallzucht von quaternären und höherwertigen Oxiden in Flussmitteln

Abstract

Dieser Aufsatz behandelt die explorative Kristallzucht in Hochtemperaturlösungen als eine Methode zur Entdeckung von komplexen Oxidmaterialien. Er gibt eine Übersicht über das Verfahren der Kristallzucht in der Schmelze (Flux‐ oder Flussmittelzüchtung) und kann als Leitfaden für die Anwendung dieser Technik dienen. Die am häufigsten eingesetzten Schmelzen werden hinsichtlich ihres Lösungsvermögens für spezifische Elemente diskutiert, und typische Reaktionsbedingungen werden zusammengestellt. Um das Leistungsvermögen der Fluxmethode zu demonstrieren, werden verschiedene kürzlich hergestellte quaternäre und höhere Oxide vorgestellt, die für das Züchten von Oxidkristallen aus spezifischen Elementen geeignet sind.

Pb2PdO2(OH)2 and Pb2PdO(OH)4(H2O): Synthesis and Crystal Growth at Ambient Conditions

“…Furthermore, for a full physical characterization, it is essential to make the newly synthesized (metastable) solids available as macroscopic crystals, which adds another hard to tackle implication to the task set. For this latter purpose, flux8 and solvothermal methods4 have been successfully employed. However, the temperatures of 200–500 °C commonly applied are still quite high.…”

Oxohydroxo‐Tellurates(VI) K2[TeO2(OH)4] and K2[Fe2TeO6(OH)2] ⋅ 2H2O from Alkaline Hydroflux

“…In 2013, the term hydroflux was mentioned again by zur Loye [15,16] . In this case, it describes an ultra‐alkaline reaction medium consisting of an approximately equimolar mixture of water and alkali metal hydroxide.…”

“…The work of zur Loye [15,16,19–28] and the recent contributions by us [29–47] give an impression of the potential of the hydroflux method. In just a few years, almost 100 new compounds were found in already extensively explored systems.…”

Synthesis of a Ferrolite: A Zeolitic All‐Iron Framework

“…[9][10][11] Thenew all-iron zeolite (ferrolite) was crystallized in ah ydroflux reaction, where Fe(NO 3 ) 3 ·9 H 2 O( 4.28 mmol), Ba(OH) 2 ·8 H 2 O( 4.28 mmol), NaOH (9 g), and H 2 O(7g)were heated at 230 8 8CinaPTFElined stainless-steel autoclave for 24 hours followed by slow cooling at ar ate of 0.3 8 8Cmin À1 to 80 8 8C. [9][10][11] Thenew all-iron zeolite (ferrolite) was crystallized in ah ydroflux reaction, where Fe(NO 3 ) 3 ·9 H 2 O( 4.28 mmol), Ba(OH) 2 ·8 H 2 O( 4.28 mmol), NaOH (9 g), and H 2 O(7g)were heated at 230 8 8CinaPTFElined stainless-steel autoclave for 24 hours followed by slow cooling at ar ate of 0.3 8 8Cmin À1 to 80 8 8C.…”

“…Thes ynthesis of this new material was enabled by our development of the hydroflux crystal growth technique,which occupies an iche area between hydrothermal synthesis and molten flux chemistry. [9][10][11] Thenew all-iron zeolite (ferrolite) was crystallized in ah ydroflux reaction, where Fe(NO 3 ) 3 ·9 H 2 O( 4.28 mmol), Ba(OH) 2 ·8 H 2 O( 4.28 mmol), NaOH (9 g), and H 2 O(7g)were heated at 230 8 8CinaPTFElined stainless-steel autoclave for 24 hours followed by slow cooling at ar ate of 0.3 8 8Cmin À1 to 80 8 8C. Block crystals measuring 0.05 to 0.1 mm in size with truncated corners were isolated in nearly quantitative yield by removing the residual flux with methanol under sonication.…”