Na₃Ca₂TaO₆, a rock-salt superstructure phase with a fully ordered cation arrangement

Abstract

The title quaternary oxide, trisodium dicalcium tantalum hexaoxide, is isostructural with Li(3)Ni(2)TaO(6), a partially ordered rock-salt phase. The Na, Ca and Ta atoms occupy octahedral sites in an orderly manner and form a cation-ordered superstructure.

Materials Discovery by Flux Crystal Growth: Quaternary and Higher Order Oxides

“…Crystals of oxides containing early transition elements, such as transparent crystals of Li 7 La 3 Zr 2 O 12 ,84 were successfully grown from a Li 2 CO 3 flux. The polycrystalline materials was mixed with the flux in a gold crucible and heated at 1040 °C for 48 h. Na 3 Ca 2 TaO 6 85 and Na 2 Ca 3 Ta 2 O 9 86 were obtained as colorless transparent crystals from the dissolution of CaCO 3 and Ta 2 O 5 in a Na 2 CO 3 flux. The starting materials were pressed into a pellet, which was heated at 1000 °C on a platinum plate, before being cooled at 3 °C per hour to 800 °C, at which point the furnace was turned off.…”

Crystal Growth of Two New Photoluminescent Oxides: Sr3Li6Nb2O11 and Sr3Li6Ta2O11

“…Niobates and tantalates in the A O− A 2 ′O− M 2 O 5 − system ( A = Ca 2+ , Sr 2+ , Ba 2+ ; A ′ = Li + , Na + , Rb + ; M = Nb 5+ /Nb 4+ , Ta 5+ /Ta 4+ ) commonly crystallize in the perovskite or perovskite-related structure types, including Ca 2 A′M 3 O 10 ( A′ = Li + , Na + , K + , Rb + , Cs + , NH 4 + , Tl + ; M = Nb 5+ , Ta 5+ ), − Ca 2 A′ 2 Ta 3 O 10 ( A′ = Li, Na), Li 2 x Ca 0.5− x TaO 3 , Li 0.2 (Ca 1− y Sr y ) 0.4 TaO 3 , Ca 4 NaNb 5 O 17 , , Ca 2 Na 2 Nb 4 O 13 , , Sr x Na 1− x NbO 3 , Ba 4 LiM 3 O 12 , − and A 3 Na M O 6 ( M = Nb, Ta), , as well as in less commonly observed structure types including Ruddlesden−Popper-related compounds (Li 4 Sr 3 Nb 6 O 20 , Li 2 SrNb 2 O 7 ), anion-deficient pyrochlores (SrNaNb 2 O 6.5 ), rock salt structures (Ca 2 Na 3 TaO 6 ), and tetragonal tungsten bronzes (Ba 2 NaNb 5 O 15 ) . In almost all cases, polycrystalline samples of these oxides were synthesized by the traditional solid-state or ion-exchange methods, ,, while single crystals were obtained from sulfate and carbonate fluxes .…”

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

“…Polykristallines Ausgangsmaterial wurde mit dem Flussmittel in einem Goldtiegel vermischt und 48 h lang auf 1040 °C erhitzt. Na 3 Ca 2 TaO 6 85 und Na 2 Ca 3 Ta 2 O 9 86 wurden als farblose transparente Kristalle durch Lösen von CaCO 3 und Ta 2 O 5 in einem Na 2 CO 3 ‐Fluss erhalten. Die Ausgangsmaterialien wurden zu einer Tablette gepresst, die auf einer Platinplatte auf 1000 °C erhitzt und dann mit 3 °C pro Stunde auf 800 °C abgekühlt wurde, worauf der Ofen ausgeschaltet wurde.…”