Si-Al distribution in high-pressure CaAl4Si2O 11 phase

A 29Si and27Al NMR study

Xianyu Xue, Shuangmeng Zhai, Masami Kanzaki

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

High-resolution 29Si and 27Al NMR techniques have been, applied to resolve the Si-Al distribution, and coordination in the high-pressure CaAl4Si2O11 (CAS) phase, a potentially important mineral in subducted crustal materials in the deep mantle that has a unique hexagonal ferrite structure containing two octahedral (M1; M2) and one trigonal bipyramidal sites. The 29Si MAS NMR spectra of the CAS phase synthesized at 20 GPa and 1400∼1600 °C show two broad, asymmetric peaks near -92.7 and -182.7 ppm with an intensity ratio of 1:3, suggesting that 1/4 of the Si are in tetrahedral coordination and 3/4 in octahedral coordination. Therefore, the trigonal bipyramidal and M1 octahedral sites are each occupied by equal proportions of Si and Al, and the former are effectively half-occupied face-sharing tetrahedra (at least for Si). The 27Al MAS and 3Q MAS NMR, spectra contain only one unresolved peak typical, of octahedral Al with a range of quadrupolar coupling constants.

Original languageEnglish
Pages (from-to)1739-1742
Number of pages4
JournalAmerican Mineralogist
Volume94
Issue number11-12
DOIs
Publication statusPublished - Nov 2009

Fingerprint

MAS
nuclear magnetic resonance
Nuclear magnetic resonance
ferrite
tetrahedrons
Minerals
Ferrite
ferrites
proportion
Earth mantle
minerals
mantle
high resolution
mineral
distribution
co-ordination

Keywords

  • Al and si coordination
  • CAS phase
  • High pressure
  • NMR spectroscopy
  • Si-Al disorder

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

Si-Al distribution in high-pressure CaAl4Si2O 11 phase : A 29Si and27Al NMR study. / Xue, Xianyu; Zhai, Shuangmeng; Kanzaki, Masami.

In: American Mineralogist, Vol. 94, No. 11-12, 11.2009, p. 1739-1742.

Research output: Contribution to journalArticle

@article{c1e114f372d24cba9e96383140bf35c5,
title = "Si-Al distribution in high-pressure CaAl4Si2O 11 phase: A 29Si and27Al NMR study",
abstract = "High-resolution 29Si and 27Al NMR techniques have been, applied to resolve the Si-Al distribution, and coordination in the high-pressure CaAl4Si2O11 (CAS) phase, a potentially important mineral in subducted crustal materials in the deep mantle that has a unique hexagonal ferrite structure containing two octahedral (M1; M2) and one trigonal bipyramidal sites. The 29Si MAS NMR spectra of the CAS phase synthesized at 20 GPa and 1400∼1600 °C show two broad, asymmetric peaks near -92.7 and -182.7 ppm with an intensity ratio of 1:3, suggesting that 1/4 of the Si are in tetrahedral coordination and 3/4 in octahedral coordination. Therefore, the trigonal bipyramidal and M1 octahedral sites are each occupied by equal proportions of Si and Al, and the former are effectively half-occupied face-sharing tetrahedra (at least for Si). The 27Al MAS and 3Q MAS NMR, spectra contain only one unresolved peak typical, of octahedral Al with a range of quadrupolar coupling constants.",
keywords = "Al and si coordination, CAS phase, High pressure, NMR spectroscopy, Si-Al disorder",
author = "Xianyu Xue and Shuangmeng Zhai and Masami Kanzaki",
year = "2009",
month = "11",
doi = "10.2138/am.2009.3348",
language = "English",
volume = "94",
pages = "1739--1742",
journal = "American Mineralogist",
issn = "0003-004X",
publisher = "Mineralogical Society of America",
number = "11-12",

}

TY - JOUR

T1 - Si-Al distribution in high-pressure CaAl4Si2O 11 phase

T2 - A 29Si and27Al NMR study

AU - Xue, Xianyu

AU - Zhai, Shuangmeng

AU - Kanzaki, Masami

PY - 2009/11

Y1 - 2009/11

N2 - High-resolution 29Si and 27Al NMR techniques have been, applied to resolve the Si-Al distribution, and coordination in the high-pressure CaAl4Si2O11 (CAS) phase, a potentially important mineral in subducted crustal materials in the deep mantle that has a unique hexagonal ferrite structure containing two octahedral (M1; M2) and one trigonal bipyramidal sites. The 29Si MAS NMR spectra of the CAS phase synthesized at 20 GPa and 1400∼1600 °C show two broad, asymmetric peaks near -92.7 and -182.7 ppm with an intensity ratio of 1:3, suggesting that 1/4 of the Si are in tetrahedral coordination and 3/4 in octahedral coordination. Therefore, the trigonal bipyramidal and M1 octahedral sites are each occupied by equal proportions of Si and Al, and the former are effectively half-occupied face-sharing tetrahedra (at least for Si). The 27Al MAS and 3Q MAS NMR, spectra contain only one unresolved peak typical, of octahedral Al with a range of quadrupolar coupling constants.

AB - High-resolution 29Si and 27Al NMR techniques have been, applied to resolve the Si-Al distribution, and coordination in the high-pressure CaAl4Si2O11 (CAS) phase, a potentially important mineral in subducted crustal materials in the deep mantle that has a unique hexagonal ferrite structure containing two octahedral (M1; M2) and one trigonal bipyramidal sites. The 29Si MAS NMR spectra of the CAS phase synthesized at 20 GPa and 1400∼1600 °C show two broad, asymmetric peaks near -92.7 and -182.7 ppm with an intensity ratio of 1:3, suggesting that 1/4 of the Si are in tetrahedral coordination and 3/4 in octahedral coordination. Therefore, the trigonal bipyramidal and M1 octahedral sites are each occupied by equal proportions of Si and Al, and the former are effectively half-occupied face-sharing tetrahedra (at least for Si). The 27Al MAS and 3Q MAS NMR, spectra contain only one unresolved peak typical, of octahedral Al with a range of quadrupolar coupling constants.

KW - Al and si coordination

KW - CAS phase

KW - High pressure

KW - NMR spectroscopy

KW - Si-Al disorder

UR - http://www.scopus.com/inward/record.url?scp=77249100759&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77249100759&partnerID=8YFLogxK

U2 - 10.2138/am.2009.3348

DO - 10.2138/am.2009.3348

M3 - Article

VL - 94

SP - 1739

EP - 1742

JO - American Mineralogist

JF - American Mineralogist

SN - 0003-004X

IS - 11-12

ER -