REDUCED ALKALINE EARTH TANTALATES

Among reduced ternary transition metal oxides, tantalates are rare, even though interesting electronic properties might be expected. Here, we report on new reduced alkaline earth tantalates Ca2Ta2O6F, Sr3-xTa5O15, and Ba2Ta15O32 grown under vacuum conditions and high temperatures. These reduced ternary tantalates are isostructural with known reduced ternary niobates, indicating a strong similarity of the crystal chemistry between the two systems. © 1997 Elsevier Science Ltd