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The Crystal Structure of the Dioctahedral Mica 2M2 Determined by High Voltage Electron Diffraction

Published online by Cambridge University Press:  01 July 2024

A. P. Zhoukhlistov ,
B. B. Zvyagin ,
S. V. Soboleva  and
A. F. Fedotov
A. P. Zhoukhlistov
Affiliation:
Academy of Sciences, Moscow, U.S.S.R.
B. B. Zvyagin
Affiliation:
Academy of Sciences, Moscow, U.S.S.R.
S. V. Soboleva
Affiliation:
Academy of Sciences, Moscow, U.S.S.R.
A. F. Fedotov
Affiliation:
Academy of Sciences, Moscow, U.S.S.R.
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Abstract

The structure of a dioctahedral 2M2 mica was defined by high voltage electron diffraction. The cell parameters are: a = 8·965, b = 5·175, c = 20·31 Å, β = 100° 40′, Z = 4, space group C2/c. Despite the peculiar character of the layer disposition (σ4 σ5 σ4 σ5), the oxygens of the layers are packed according to the cubic law. Consequently, the interlayer cations K have a trigonal prismatic coordination. The angle of tetrahedral twist is 11° 20′. The interatomic distances T-O indicate ordered replacements of Al for Si.

Resume

Resume

La structure d’un mica dioctaédrique 2M2 a été définie par diffraction électronique à haute tension. Les paramètres de la maille sont: a = 8,965. b = 5,175, c = 20,31 Å, β = 100° 40′, Z = 4, groupe spatial C2/c. En dépit du caractère particulier de la disposition des feuillets (σ4 σ5 σ4 σ5), les atomes d’oxygène des feuillets sont ernpilés selon un arrangement cubique. Ainsi. les cations K interfeuillets ont une coordination trigonale prismatique. L’angle de rotation du tétraèdre est 11° 20′. Les distances interatomiques T-O indiquent l’existence de remplacements Al-Si ordonnés.

Kurzreferat

Kurzreferat

Die Struktur eines dioktaedrischen 2M2-Glimmers wurde durch Hochspannungselektronenbeugung bestimmt. Die Zellparameter sind: a = 8,965. b = 5,175, c = 20,31 Å, β = 100° 40′, Z = 4, Raumgruppe C2/c. Trotz des eigenartigen Charakters der Schichtgliederung (σ4 σ5 σ4 σ5) sind die Sauerstoffe der Schichten nach dem kubischen Gesetz angeordnet Die Zwischenschichtkaliumionen besitzen infolgedessen eine trigonale prismatische Zuordnung. Der Winkel der Tetraederdrehung beträgt 11° 20′. Die Atomabstände T-O weisen auf geordneten Ersatz von Si durch Al hin.

Резюме

Резюме

Дифракцией электронов высокого напряжения определялась структура диоктаэдральной слюды 2М2. Параметры ячейки следующие: a =8,965, b = 5,175, с = 20,31 Å, β = 100°40’, Z = 4, пространственная группа С2/с. Несмотря на специфический характер расположения слоев (σ4σ5σ4σ5), сложение кислородов в слоях следует кубическому закону. Следовательно, катионы промежуточного слоя К имеют треугольную призматическую координацию. Углом тетраэдрального витка является 11°20’. Межатомные пространства Т-О указывают на упорядоченную замену Si на Аl.

Type
Research Article
Information
Clays and Clay Minerals , Volume 21 , Issue 6 , December 1973 , pp. 465 - 470
Copyright
Copyright © 1973 The Clay Minerals Society

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