Crystal structure of the K, Ti analogue of ilímaussite-(Ce), (Ba,K,Na,Ca)11–12(REE,Fe,Th)4(Ti,Nb)6(Si6O18)4(OH)12·4.5 H2O: revision of structure model and structural formula

Sergey V. Krivovichev; V. N. Yakovenchuk; Th. Armbruster; Y. A. Pakhomovskiy; W. Depmeier

doi:10.1524/zkri.218.6.392.20721

Published by De Gruyter (O) September 25, 2009

Crystal structure of the K, Ti analogue of ilímaussite-(Ce), (Ba,K,Na,Ca)_11–12(REE,Fe,Th)₄(Ti,Nb)₆(Si₆O₁₈)₄(OH)₁₂·4.5 H₂O: revision of structure model and structural formula

Sergey V. Krivovichev , V. N. Yakovenchuk , Th. Armbruster , Y. A. Pakhomovskiy and W. Depmeier

From the journal Zeitschrift für Kristallographie - Crystalline Materials

https://doi.org/10.1524/zkri.218.6.392.20721

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Abstract

The crystal structure of the K, Ti analogue of il¡maussite-(Ce), (Ba,K,Na,Ca)_11–12(REE,Fe,Th)₄(Ti,Nb)₆(Si₆O₁₈)₄(OH)₁₂·4.5 H₂O, from the Yukspor mountain, Khibiny massif, Kola peninsula, Russia, has been solved by direct methods and refined to R₁ = 0.077 on the basis of 1762 reflections with |F_o| ≥ 4σ_F. The mineral is rhombohedral, R32, a = 10.708(2), c = 60.073(11) Å, V = 5965.2(17) Å³. The structure is based upon a heteropolyhedral framework that consists of layers of corner-linked polyhedra. The SiO₄ tetrahedra share corners to form 6-membered rings which are further interlinked via REEO₆ trigonal prisms and Tiφ₆ octahedra (φ = O, OH). The obtained structure model is different from that recently reported by Rastsvetaeva et al. (2003) which is considered incorrect.

Published Online: 2009-9-25

Published in Print: 2003-6-1

Crystal structure of the K, Ti analogue of ilímaussite-(Ce), (Ba,K,Na,Ca)_11–12(REE,Fe,Th)₄(Ti,Nb)₆(Si₆O₁₈)₄(OH)₁₂·4.5 H₂O: revision of structure model and structural formula

Abstract

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