File.

The sub-menu File (Fig. 2) allows:

Fig. 2

  • to start with a "New" project;
  • to "Load" an existing input file (*.qua);
  • to load a binary file (*.bin) produced by a previous run ("Load old Project");
  • to "Save" the project at a given stage; 
  • to "Restore" a saved project;
  • to access to the "Data Bank";
  • to "Exit" from the program

 

New.

The option New opens a dialog-box to supply to the program all the necessary input data. It is organized in 5 folders: General, Pattern, Phases, Instrument, Corrections.

General.

The folder General is shown in Fig. 4.

 It includes the following fields:

- Home Directory (not editable).

It is the directory containing the program and all its files (SirWare files).

- Quanto work-files Directory.

It is the working directory chosen by the user (Browse button); all the files produced by the run will be stored in this directory.

- Project Name.

It is the name of the project chosen by the user. All the input data supplied to the program will be stored into the input file project.qua; data and results produced at each program stage will be stored into a binary file project.bin; the ascii output filename will be project.out.

 

- Job title.

It is a caption line for user’s comments (up to 80 characters).

 

Pattern.

The folder Pattern is shown in Fig. 5. It allows to supply all the information about the measured counts. It includes the following fields:

 

- Pattern filename.

It is the name of the ascii file containing the experimental counts; it can be edited or selected by the browse button.

- File content.

This section allows to supply

- starting 2-theta (value in degrees corresponding to the first count in the pattern filename);

- final 2-theta (value in degrees £ the last count in the pattern filename);

- angular step (in degrees);

- # of counts per record (number of counts per line);

- Caption line: the cross indicates that a comment is the first line in the pattern filename.

 

- Format section.

This section allows to supply the format (according to the Fortran syntax) of data stored into the pattern filename. The program reads only the counts and, if any, the corresponding e.s.d. [ cross in sigma(counts)]

The free format can be used when the file contains

- only counts

- angles and counts

- angles, counts and sigma(counts)

- a raw of 2-theta and a raw of counts.

 

The user format must be specified if the file contains additional fields, in order to skip them.

In Fig. 6 is shown an example of pattern file with the typical GSAS format: in this example the correct Format to be introduced is (10(2x,f6.0)).

 

Phases.

The folder Phases is shown in Fig. 7. It allows to supply:

 

- the structural model of phases in the mixture selected from the "Quanto Data Bank" (*.pha files);

 

- a "Parameter file" (*.par) for each phase. This kind of file contains information about the profile shape function, mixing and FWHM parameters, Preferred Orientation vectors. The same information can be supplied by graphics (see "Parameters" item);

 

- an "Intensity file" (*.hkl) for each phase. This kind of file contains a list of reflections with the corresponding |Fo| or |Fo|2 values; they can be used instead of those calculated from the model.

 

- The "Standard" phase to estimate the amorphous content in the mixture.

 

Parameters and Intensity files are ascii files produced by the user (Parameters file) or by other programs (Intensity file). The corresponding filenames require the same name of the .pha file for a given phase. As an example, if the phase filename is corundum.pha, the corresponding Parameter file must be corundum.par and the Intensity file must be corundum.hkl.

Parameters and Intensity files can be assigned to a given phase after that the .pha file has been selected.

 

To supply the structural models: after selecting Phases in the Select section, click on "Add" button: the dialog-box shown in Fig. 8 is open. By means of it the user can move to the Quanto Data Bank directory (or any other) and select the required .pha files. When this operation has been completed click on "OK" button: the list of phases will be displayed on the right part of the window in Fig. 7.

 

To supply a Parameters file: after selecting Parameters file in the Select section, click on the .pha file of the desired phase in the phases list at the right of the window, then click on "Add" button: the dialog-box shown in Fig. 9 is open. By means of it the user can move to the directory where the file is stored and select it; click on "OK" button to confirm the selection. The selected filename will be displayed at the right of the corresponding .pha (see Fig. 12).

 

To supply an Intensity file: after selecting Intensity file in the Select section, click on the .pha file of the desired phase in the phases list at the right of the window, then click on "Add" button: the dialog-box shown in Fig. 10 is open. By means of it the user can move to the directory where the file is stored and select it; clicking on "OK" button the dialog-box shown in Fig. 11 is open. It allows to specify the content of the .hkl file:

 

- the number of reflections per record

- if |Fo| or |Fo|2 values are supplied

- if sigma(|Fo|) are supplied

 

The Format of data in the .hkl file must be supplied as the first line of the same file.

The Intensity filename will be displayed at the right of the corresponding .pha (see Fig. 12).

 

To indicate the Standard phase: click on the Standard button and the dialog-box shown in Fig. 13 is open. It allows to select the phase added as a standard among the phases component the mixture and the known weight percentage (xs × 100). The weight amorphous fraction xa is derived as follow:

 

xa = 1.0 – xs ¤ x’s

 

x’s is the weight fraction of the standard phase estimated by Rietveld.

 

To Delete a selected file. The Delete button allows to eliminate one or more files (.pha, .par, .hkl) from the phases list on the right of the window. As for the Add button, the user has to select the type of file in the Select section, then click on the raw of the desired phase in the phases list and, finally, to click on the Delete button.

 

Instrument.

The folder Instrument is shown in Fig. 14. It allows

 

- to select the kind of Source used for data collection (X-Ray Home tube, Synchrotron, constant wavelength Neutron);

 

- to select the Geometry of the instrumental apparatus (Bragg-Brentano diffractometer in reflection or in trasmission mode with a fixed divergence slit, Debye-Scherrer or Guinier camera);

 

- to supply the values of the wavelength(s) l .

For laboratory data (the most employed for quantitative determination) l values for the doublet ka 1 / ka 2 and the intensity ratio a 2 / a 1 can be supplied;

 

 

- to include/exclude the anomalous scattering factors in/from the structure factors calculations (cross the field for including them).

 

It has been previously outlined that the SirWare.xen file distributed with the Quanto program contains the mass absorption coefficient (m ¤ r ) and the anomalous scattering factors (f’ and f’’) for each chemical specie up to Cf (????) only for l ka of Cu and Mo targets. When a different wavelength is used for data collection, m ¤ r , f’ and f’’ for each chemical specie must be supplied by an external file named scafact.dat and shown in Fig. 15.

 

Corrections.

The folder Corrections is shown in Fig. 16. It allows to supply the information for suitable experimental corrections: the Monochromator information for Polarization correction (Pol) and the absorption correction for data collected in trasmission mode. The Polarization correction is grouped with the Lorentz correction

 

Li= 1.0 ¤ ( sinq i sin2q i )

 

2q i = Bragg angle of i-th reflection

 

 

The considered cases and relative corrections are as follow:

 

POLARIZATION CORRECION

 

X-Ray Home Tube (Totally non polarized incident beam, Azaroff 1955, Acta Cryst., 8, 701)

 

- No Monochromator

 

Poli = ( 1.0 + cos22q i ) ¤ 2

 

 

 

- Monochromator on the incident beam

 

Poli = ( 1.0 + Apol× cos22q i ) ¤ ( 1.0 + Apol )

 

 

 

- Monochromator on the diffrated beam

 

Poli = ( 1.0 + Apol× cos22q i ) ¤ ( 1.0 + cos22q i )

 

 

Apol = Polarization factor = cos22q M

 

2q M = Bragg angle of Monochromator crystal

 

 

Synchrotron or Neutron ( For synchrotron, incident beam totally polarized in the vertical plane, Kahn et al., 1982, J. Appl. Cryst., 15, 330-337)

 

 

Poli = 1.0

 

 

 

ABSORPTION CORRECTION

 

The correction is applied to the measured count at each step in the pattern as follow:

 

Yo(i) = Y’o(i) × T(i)

 

Y’o(i) = measured count at i-th step

T(i) = absorption correction

 

 

- Bragg-Brentano geometry in trasmission mode (flat sample)

 

Ti = e-(m t ¤ cosq i) ¤ cosq i

 

m = linear absorption coefficient of sample

 

t = sample’s thickness

 

q i = i-th step in the pattern

 

 

 

- Debye-scherrer geometry (cylindrical sample)

 

Ti = e-Corr(i)

 

Corr(i) = (1.7133 – 0.0368 × sin2q i ) m R + (0.0927 – 0.375 × sin2q i ) (m R)2

 

m = linear absorption coefficient of sample

 

R = capillary’s radius

 

q i = i-th step in the pattern