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De nouveaux oxydes a reseau forme d'octaedres NbO6 (TaO6) et de groupes Si2O7: Les phases A3Ta6Si4O26 (A = Ba, Sr) et K6M6Si4O26 (M = Nb, Ta)

1976; Elsevier BV; Volume: 11; Issue: 8 Linguagem: Inglês

10.1016/0025-5408(76)90160-4

1873-4227

J. Choisnet, Ninh Nguyen, D. Groult, Bernard Raveau,

Catalysis and Oxidation Reactions

New oxides, A3 Ta6 Si4 O26 (A = Ba, Sr) and K6 M6 Si4 O26 (M = Nb, Ta) have been synthesized. Their structure shows an interesting feature: Si2 O7 groups are linked with Nb O6 (Ta O6) octahedra so as to create distorted pentagonal channels. These channels have an half occupancy for A3 Ta6 Si4 O26; they are full for K6 M6 Si4 O26. The stuctures are basically the same for the two types of compounds. Supplementary potassium of K6 M6 Si4 O26 have two additionnal neighbor oxygen, of the Si O Si bridge.