Non-stoechiométrie par "intercroissance" dans les siliconiobates de baryum. Les composés (Ba 3Nb 6Si 4O 26) n· Ba 3Nb 4Ti 4O 21

A new family with general formula (Ba ₃Nb ₆Si ₄O ₂₆) _nBa ₃ Nb ₄Ti ₄O ₂₁ (2 n takes an integral value) was synthesized in Ba ₃Nb ₆Si ₄O ₂₆Ba ₃Nb ₄Ti ₄O ₂₁ system. The structure of these compounds shows the intergrowth of two structural types: Ba ₃Nb ₆Si ₄O ₂₆ and Ba ₃Nb ₄Ti ₄O ₂₁. Members of this family with n values = 1, 2, and 3 have been studied by X-ray diffraction and electron microscopy. For Ba ₁₅Nb ₂₈Ti ₄Si ₁₆O ₁₂₅ ( n = 4) composition, electron diffraction results are consistent with the existence of different compositions: n = 3, n = 5, and n = 4.5. n = 4 member was obtained by heating at 1300°C for long periods.