The determination of site occupancies in garnet by planar and axial ALCHEMI

Max T. Otten; P R Buseck

doi:10.1016/0304-3991(87)90160-4

The determination of site occupancies in garnet by planar and axial ALCHEMI

Max T. Otten
, P R Buseck

Earth and Space Exploration, School of (SESE)

Research output: Contribution to journal › Article › peer-review

16 Scopus citations

Abstract

The application of ALCHEMI (Atom Location by Channelling-Enhanced MIcroanalysis) to the determination of the cation distribution between the X, Y and Z sites in garnet has been studied. Planar ALCHEMI as well as the novel axial-ALCHEMI technique were used. Five types of diffracting conditions were used, two for planar ALCHEMI with electron channelling along (444) planes, and three for axial ALCHEMI along the [111], [211] and [311] zone axes. None of these allows a distinction between the large X and small Z sites, but these two together can be differentiated from the intermediate Y site. The channelling for planar ALCHEMI is too weak to produce reliable results. Axial ALCHEMI, especially for the [111] and [311] axes, gives good results, but the data must be corrected because X-ray generation is not perfectly localized. Correction factors for localisation are given for Mg and Ca on the X site, and for Ti and Cr on the Y site.

Original language	English (US)
Pages (from-to)	151-158
Number of pages	8
Journal	Ultramicroscopy
Volume	23
Issue number	2
DOIs	https://doi.org/10.1016/0304-3991(87)90160-4
State	Published - 1987

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Atomic and Molecular Physics, and Optics
Instrumentation

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title = "The determination of site occupancies in garnet by planar and axial ALCHEMI",

abstract = "The application of ALCHEMI (Atom Location by Channelling-Enhanced MIcroanalysis) to the determination of the cation distribution between the X, Y and Z sites in garnet has been studied. Planar ALCHEMI as well as the novel axial-ALCHEMI technique were used. Five types of diffracting conditions were used, two for planar ALCHEMI with electron channelling along (444) planes, and three for axial ALCHEMI along the [111], [211] and [311] zone axes. None of these allows a distinction between the large X and small Z sites, but these two together can be differentiated from the intermediate Y site. The channelling for planar ALCHEMI is too weak to produce reliable results. Axial ALCHEMI, especially for the [111] and [311] axes, gives good results, but the data must be corrected because X-ray generation is not perfectly localized. Correction factors for localisation are given for Mg and Ca on the X site, and for Ti and Cr on the Y site.",

author = "Otten, \{Max T.\} and Buseck, \{P R\}",

note = "Funding Information: This work was supportedb y grant EAR-8408168f rom the NSF Earth ScienceD ivision. Microscopyw asp erformeadt the ASU Centerf or Solid StateS cience,w hich is supportedb y the NSF and ASU. We thank Dr. P.G. Self for his advicea nd FORTRAN programsD, r. P. Rez and Dr. J.C.H. Spencef or helpfuld iscussionsD, r. J.R. Smytha nd Dr.T c' McCormickf or providingth e pyrope specimena nd microprobea nalysis, and J.C. WheatleyA,. Higgs and K. Weiss for technical support.",

year = "1987",

doi = "10.1016/0304-3991(87)90160-4",

language = "English (US)",

volume = "23",

pages = "151--158",

journal = "Ultramicroscopy",

issn = "0304-3991",

publisher = "Elsevier B.V.",

number = "2",

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AU - Otten, Max T.

AU - Buseck, P R

N1 - Funding Information: This work was supportedb y grant EAR-8408168f rom the NSF Earth ScienceD ivision. Microscopyw asp erformeadt the ASU Centerf or Solid StateS cience,w hich is supportedb y the NSF and ASU. We thank Dr. P.G. Self for his advicea nd FORTRAN programsD, r. P. Rez and Dr. J.C.H. Spencef or helpfuld iscussionsD, r. J.R. Smytha nd Dr.T c' McCormickf or providingth e pyrope specimena nd microprobea nalysis, and J.C. WheatleyA,. Higgs and K. Weiss for technical support.

PY - 1987

Y1 - 1987

N2 - The application of ALCHEMI (Atom Location by Channelling-Enhanced MIcroanalysis) to the determination of the cation distribution between the X, Y and Z sites in garnet has been studied. Planar ALCHEMI as well as the novel axial-ALCHEMI technique were used. Five types of diffracting conditions were used, two for planar ALCHEMI with electron channelling along (444) planes, and three for axial ALCHEMI along the [111], [211] and [311] zone axes. None of these allows a distinction between the large X and small Z sites, but these two together can be differentiated from the intermediate Y site. The channelling for planar ALCHEMI is too weak to produce reliable results. Axial ALCHEMI, especially for the [111] and [311] axes, gives good results, but the data must be corrected because X-ray generation is not perfectly localized. Correction factors for localisation are given for Mg and Ca on the X site, and for Ti and Cr on the Y site.

AB - The application of ALCHEMI (Atom Location by Channelling-Enhanced MIcroanalysis) to the determination of the cation distribution between the X, Y and Z sites in garnet has been studied. Planar ALCHEMI as well as the novel axial-ALCHEMI technique were used. Five types of diffracting conditions were used, two for planar ALCHEMI with electron channelling along (444) planes, and three for axial ALCHEMI along the [111], [211] and [311] zone axes. None of these allows a distinction between the large X and small Z sites, but these two together can be differentiated from the intermediate Y site. The channelling for planar ALCHEMI is too weak to produce reliable results. Axial ALCHEMI, especially for the [111] and [311] axes, gives good results, but the data must be corrected because X-ray generation is not perfectly localized. Correction factors for localisation are given for Mg and Ca on the X site, and for Ti and Cr on the Y site.

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The determination of site occupancies in garnet by planar and axial ALCHEMI

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