Patterns indexing programs

The results obtained in the present work show that the developed methods can be applied successfully to oblique texture electron diffraction patterns. The program TexPat has been designed to produce accurate lattice parameters and intensities. Indexing oblique texture electron diffraction patterns from structures with S5mrmetry lower than orthorhombic remains quite difficult task due to the geometrical properties of texture patterns. This difficulty is overcome by the introduction of semi-automatic algorithms for the indexing. 

Alloys were prepared from metals of 99.9% purity by arc melting on a water-cooled copper hearth under an argon atmosphere. The alloys were homogenized at 800° C. Diffraction patterns of cast material were equally as sharp as those of homogenized alloys. X-ray diffraction patterns were taken with filtered FeKa radiation. Computer programs verified x-ray pattern indexes. 

Kohl/TMO Trial and error indexing program for powder patterns of monoclinic substances, F. Kohlbeck and E. M. Horl, J. Appl. Crystallogr., 1978, 11, 60 61 Crysfire... 

After establishing a phylogenetic tree, further analysis can be pursued to determine patterns in diversity within and across communities. Phylogenetic diversity (PD) can be determined with the aid of programs like DOTUR (84), and DIVERSITY (85). DOTUR calculates the Shannon-Weiner index, a calculation of diversity based on how predictable the community is, and the Simpson diversity index, a calculation based on both the number of different samples in a community and their proportions in addition to several richness estimators. DIVERSITY calculates PD a diversity index that summates... 

The main sharp features in the PXD pattern were indexed, with the aid of the visser program [48], on the basis of a monoclinic unit cell, with a = 6.509(8)A, b =... 

Initial PXD patterns of phase B materials (encountered, as above, when fumed silica was used as the Si02 source, or when products were crystallized in the presence of LiOH [47]) were clearly multiphasic, but by cross comparing reflection appearances and intensities in data from three different samples, it proved possible to assign the main peaks in the PXD patterns to one of three phases, of which the predominant was labelled B. Attempts at indexing using the treor program [55] based on the positions of a number of the peaks ascribed to phase B yielded two possible unit cells, one tetragonal (with a = 8.812(1)A and c = 12.460(2)A) and the other monoclinic (with a = 6.950(3)A, b = 12.467(5)A, c = 4.911(1)A and P = 116.24(2)°). A repeated synthesis of phase B yielded a much cleaner PXD pattern, that showed a well-defined (if weak) peak at 20 -12.3° which indicated the former cell to... 

Then TREOR (4) program [18] was used to index the pattern automatically and finally all peaks were indexed by orthorhombic system, resulting in the figure of merit, M(10)=32, F(10)=21. SOS (II) program [16] was performed to refine the cell edges (a = 0.8969(7) nm, b = 0.7011(8) nm, c = 0.596(1) nm) and calculated out more indices of the reflections. The cell volume is about half of that of cubic modification. So the orthorhombic system (hereafter 5 -ZrW, 5M00 4O8) is a new crystal structure other than the pressure-induced orthorhombic y-ZrW208 structural model. 

Figure 1. The indexing of 6 -Zr W, 6M004O,. The indices were calculated from the TREOR program. The tick marks under the pattern were demonstrations of the failed index by known structural models. The tick marks were the allowed Bragg reflection positions of space groups of P(-3)c (the lowest), Pa(-3) (middle low), P2 3 (middle up) and P 2,2, 2, (top) models of ZrWjO, or ZrMo20j. The inset emphasizes that both indices 110 and 101 can not be indexed by any structure.

Electron Microdiffraction. Spence and Zuo, 1992. Contains well-dociunented Fortran listings for programs to simulate CBED patterns by Bloch Wave method, and multislice. Indexed patterns shown with HOLZ to speed indexing. 

IdealMicroscope. A Macintosh program helps index diffraction patterns, find excitation errors and structure factors, draw crystal structures, K-hnes, stereograms, CBED geometry, etc. Contact sharon emlahsoftware.com. 

These data were taken from Kemmit et al. all other cell parameters were obtained in this work from XRDP taken with Cu Ko radiation (Ni filter), the indexing being carried out with the program ERACEL which refines lattice parameters applying a Nelson—Riley extrapolation function. Eight out of 23 lines in the powder pattern of the compound could not be indexed on the basis of a rhombohedral unit cell the authenticity of the compound is therefore doubtful. 

---