Dataset for "Pressure-induced symmetry changes in body-centred cubic zeolites"

Data collection method:

The data within this archive was collected on the high pressure X-ray diffraction ID15B beamline at the European Synchrotron Radiation Facility (ESRF) in Frenoble, France. The data collection procedure was as follows: The incident X-ray radiation used of wavelength 0.4113 A (Angstroms), and silicon was used to calibrate the detector parameters. Each zeolite sample was loaded into a diamond anvil cell (DAC), suspended in Daphne 7373 oil. Also included in the DAC was a ruby chip, which was used to estimate the applied pressure in the DAC. This was achieved by exciting the ruby chip with a laser and detecting the shift of the R1 fluorescence emission line. The pressure was increased sequentially, with three 2D diffraction patterns taken at each pressure point. The pressure was record before and after each pressure point, with an average pressure calculated. The pressure was increased until pressure-induced amorphisation was imminent, upon which the DAC was depressurised with a number of diffraction patterns being taken during the decompression cycle.

Data processing and preparation activities:

Prior to data analysis the X-ray diffraction patterns were processed in the following way: At each pressure point three 2D diffraction patterns were taken. These three patterns were averaged in the FIT2D software, to produce an average image. Following this, the 2D area of the image was integrated over to produce a 1D powder diffraction pattern in the Dioptas software. This produced the .xy data files found in this archive. These .xy data files were subsequently used in order to calculate unit cell parameters. This was achieved by performing Pawley refinements using the TOPAS Academic software. The refinement at ambient conditions was performed manually, with the Batch mode used for subsequent refinements. This is a iterative process, where the input file for each pressure point is the output structure from the previous pressure point. The space groups used for each zeolite during the Pawley refinements were as follows: Zeolite Na-X (Fd-3m) Zeolite RHO C-form (Im-3m) Zeolite RHO A-form (I-43m) Zeolite ZK-5 Cubic (Im-3m) Zeolite ZK-5 Tetragonal (I4/mmm) The bulk moduli for each zeolite sample was determined using the PASCal webtool. Only the 0-2.2 GPa data range was used, and fitted to both the 2nd and 3rd order Birch-Murnaghan equations of state. These fits were weighted using the 0.1 GPa estimated error in the pressure within the DAC. The GASP software was used to simulate the flexibility windows of the 18C6 containing and calcined zeolite frameworks.