NBS*AIDS83 is a large, dynamic and evolving program with over 17 000 statements and 100 subroutines. Over the years, many scientists have made contributions to the program. Many man-years have been invested in creating the software and in devising the theory underlying many of the routines. Because numerous commercial computer programs use the output from NBS*AIDS83, every effort has been made during program revisions and expansions to keep the formats for all existing data items constant.
True real time search/match programs are not being developed by the JCPDS-ICDD because many are available from APD manufacturers or software developers. The JCPDS-ICDD considers itself a database producer, not a software house, but it does distribute programs developed by others. As soon as the PDF became available in computer-readable form in about 1963, several groups developed search programs. Some of these older programs are still being improved, and many new ones are being developed by equipment manufacturers and individual entrepreneurs. The JCPDS-ICDD will distribute any program in the public domain which will be supported by the authors. Presently, only three PDF programs fall into this category along with two for NIST Crystal Data and one for the Electron Diffraction Database. The JCPDS-ICDD maintains a public bulletin board and other Internet access, but does not, at the present allow searching of its files by users.
Pcpdfwin Jcpds Software 13
Download File: https://urlcod.com/2vJ2mk
Powder X-ray Diffraction (PXRD) is a decisive tool in identifying polycrystalline materials by their unique diffraction patterns and is one of the best common analytical methods for nondestructive technique which provides information on structures, phases, texture, and other structural parameters of grain size, crystallinity, strain for characterizing crystalline materials about the composition of the solid crystalline material and are especially significant for the analysis of solid materials in forensic science for the forensic identification of unknown solid [1]. High-resolution PXRD patterns provide good data to determine the phase composition of crystalline samples, yet morphology and particle shape/size can induce severe preferential orientation that can degrade the utility of XRD powder data. Indeed the morphology of a stone can even induce to adopt the X-ray diffraction technique in identification of unknown solid samples [2]. Very small changes in the X-ray powder diffraction pattern may appear as a new peak(s) or shoulders or shifts in the peak position due to impurity of the solid sample or some other well-defined crystalline material adhered with the very high percentage of the solid sample can imply the presence of a new form of crystal components [3] [4]. X-ray diffraction is the principle method of characterization and its simplicity and advantages of the powder diffraction technique can help to identify the unknown material after comparing with the diffraction spectrum of the specimen material provided by the Joint Committee for Powder Diffraction File (JCPDF) [5] inbuilt in the software and licensed.
The analysis has been constrained to a total of 100% relative intensity which will be collected from each peak. The d spacing and the intensity data has been compared to similar data in the Joint Committee on Powder Diffraction Standards (JCDPS) provide with the software in the Philips (Panalytical) X-PERT PRO, Dy993 XRPD.
X-ray diffraction patterns were obtained using a Philips DY993, X-PERT PRO X-ray Powder Diffractometer equipped with proportional detector. The sample was exposed with the X-rays produced under the copper target (1.5418 Å) and diffracted data was collected through the proportional counter. The 2θ, d, relative intensity etc. values have been obtained. Accordingly, the spectrum pattern obtained from the X-ray powder diffraction has been analysed eliminating the kα values and then the peak has been searched using the software X-PERT PRO ver 3.0. Phase identification was performed using the software, search Match ver 3.01, from Philips and the PDF database file version 2003 from ICDD.
On the basis of the JCPDS, the peaks were indexed and analysed for the identification of minerals the stone sample contains. The Hanawalt procedure, prevalently adapted to the diffractometric technique [8] [9] [10] [11] has been used in identification of mineral contents in the stone sample and then by searching the crystalline component phases of a mixture or unknown in its X-ray diffraction pattern using PCPDFWIN software which can retrieve/display for accessing records from the search from JCPDS having 60,000 compounds. Indexation of the powder pattern and calculation of the lattice constant(s) have been carried out manually by using the method of sin2θ and experimental d values respectively. Alpha-2 Stripping, Background subtraction and Indexation has also been carried out using the procedure Treor incorporated in the POWDER X [12] software for an intermediate check if the background subtraction and indexation do compromise with the Treor inbuilt with the Fullprof [13] suite of programs. The indexing of this pattern is shown in Table 1.
The data thus obtained from POWDER X has been subjected to Rietveld refinement using Fullprof Suit of Programs [13], General Structure Analysis System (GSAS) [14] software packages. The refinement was conducted based on the model for the crystal structure, peak profile, background intensities, lattice constants, atomic position etc. the refinement method based on the likelihood estimation of fluorapatite Ca3(PO4)3F [15] [16], anglesite PbSO4 [17] and barite BaSO4 [18] have been carried and demonstrated out using DBWS, Fullprof and RIETAN-FP software packages [19]. The structure of a novel layered aluminum methylphosphonate, Al2(CH3PO3)3, has been solved from X-ray powder diffraction data by simulated annealing of five independent structural sub-units, revealing a combination of four-and five-fold coordinated aluminums within the
The crystallographic properties have been uniformly maintained in both the two software packages for getting the results from the refinement of the data. The structure, thus, obtained is as summarized below.
The software, Fullprof-Suit of programs, was employed for refinement of the powder data thus obtained from the X-ray powder diffractometer as described. The matching .cif file as suspected was chosen from Crystallographic Open Data Base [24] along with input raw data in the .rd format obtained from the X-ray diffractometer. The procedure as described in the Fullprof user manual was followed for refining the crystallographic parameters such as unit cell values, atomic coordinates, atomic displacements, background of the spectrum, the Kα removed original powder data of the spectrum, asymmetric data sets etc.
The refinement was also carried out using the software GSAS with the Raw XRD data and CIF file downloaded from open crystallographic database. The weighted R value is converged as 13.38% with R background 17.45%. The unit cell parameters were, a = b = c = 5. 5.97822 Å, α = β = γ = 90. The limit values refined is from 2 to 100 and the converged structure is placed in van der walls model (VDW) model in Figure 4 and Figure 5.
The cell lattice constant of the PbS crystallites was determined from the XRD pattern as 5.935 which is the same as standard phase PbS (5.94 Å) reported [25] as experimentally proved from the XRD results on the Galena synthesized. From the calculations of the indices [26] hkl presented in Table 2 the unit cell is falling under cubic FCC lattices and the same values have been calculated by the PowderX Diffraction analysis software.
This study has been used to identify and confirm the unknown stone which was subjected to identify for the forensic purpose. The data collected using the powder X-ray diffraction was subjected to analysis with the Rietveld techniques with the help of two crystallographic software packages, in order to cross-check the results, such as Fullprof and GSAS both ended elucidating the similar molecular structure of the unknown stone as PbS, Galena by converging both the unit parameters of unknown stone a = b = c = 5.93557, α = β = γ = 90 and a = b = c = 5.97822, α = β = γ = 90 respectively and also their atomic positions with Vander Waals radii and temperature factors are:
Hence, on the basis of the crystal unit cell parameters of the unknown stone, their coordinates and the peak positions at 2θ values and the structure of the molecule PbS elucidated by these two refinement software packages used in this study also in addition to the physical parameters, which are very essential to direct the study in this direction, the authors have concluded that this unknown stone could be only belonged to PbS, Galena and nothing otherwise. 2ff7e9595c
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