TY - JOUR
T1 - The determination of site occupancies in garnet by planar and axial ALCHEMI
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.
UR - http://www.scopus.com/inward/record.url?scp=0023513527&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0023513527&partnerID=8YFLogxK
U2 - 10.1016/0304-3991(87)90160-4
DO - 10.1016/0304-3991(87)90160-4
M3 - Article
AN - SCOPUS:0023513527
SN - 0304-3991
VL - 23
SP - 151
EP - 158
JO - Ultramicroscopy
JF - Ultramicroscopy
IS - 2
ER -