GENERAL X-RAY SERVICE OF THE UPV/EHU: MOLECULES AND MATERIAL UNIT

Single crystal sample:

• Visual selection and preparation (assembly) of the glass. The samples are accepted as crystals previously filtered or in solution, being the latter option preferable in many cases.
• Preliminary quality measurements and preliminary data collection, time in which the single crystal to be measured is selected, the parameters of the unit cell, as well as its (preliminary) symmetry, are determined. If necessary, with this information the ICSD and CSD crystallographic databases are consulted to determine if the crystal phase in question has already been determined and published in international databases. If not, preliminary data collection allows selecting the most suitable diffractometer and optimizing the measurement conditions: temperature, angular interval, time, ...
• Collection of diffraction data. By default, data collection is done at 100K, except in cases where the user requests otherwise, or preliminary data indicates the formation of a twin, undesired phase transition, crystal degradation, or other undesired effect. by lowering the temperature. In any case, data collection can be carried out in a wide temperature range (10-600K) and can be carried out at various temperatures for phase transition studies.
• Data treatment. The process can end here if the user has enough knowledge to solve and refine the structure.
• Structural resolution, fine-tuning and presentation of results (report). The results obtained are sent to the users in the form of reports, graphs and / or tables, always providing the source data collected by the diffractometer, as well as information related to the equipment used, measurement conditions, etc. The complete CIF file is delivered, ready for deposit in the databases and / or publication.

Polycrystalline sample:

• Measurement and treatment of diffractograms: using the specific software of the diffractometers, the measurement programs are prepared according to the needs of the users.
• Phase identification: for users who require it, phase identification is carried out using specific software, in combination with the ICDD PDF2-4 database.
• Data processing for analysis of crystallinity, crystal domain size, austenite content, microdiffification, etc. Data processing is carried out both at the level of maximum individual diffraction and by means of complete diffraction diagram treatments.
• Analysis of the evolution of the intensities and positions depending on the orientation of the samples; Texture (pole figures) and Stress (residual stresses).
• Analysis of capillary samples (transmission) and high resolution measurements with monochromatic beam.
• Diffraction measurements from low angular positions, XRR and SAXS configurations.
• Measures of grazing incidence to determine surface gradients.
• Possibility of orientation of large monocrystals to determine lattice planes.
• Quantitative analysis by means of the theoretical simulation of the diffraction diagrams based on full-profile refinements with a structural model for both pure phases and compound mixtures.
• Data presentation: the results obtained are sent to users in the form of reports, graphs and / or tables, always providing the source data collected by the diffractometer. Likewise, these users are provided with information regarding the equipment used, measurement conditions, the methodology followed for preparing the samples, etc.
• Training through specific courses. Teaching support in different grades and masters.