The high resolution powder diffractometer SPODI is designed for the structure solution and Rietveld refinement of structural parameters on crystalline powders. The instrument is characterized by a very high monochromator take-off angle of 155° (standard configuration). Optionally, a take-off angle of 135° is available.

The detector array consists of 80 3He position sensitive detector tubes (300 mm active height) with fixed Soller collimators of 10‘ horizontal divergence. The multidetector of SPODI spans an angular range of 2θ = 160°. As each detector covers 2° corresponding to 160° / 80 detectors. The data collection is performed via stepwise positioning of the detector array to obtain a diffraction pattern of the desired step width (typically 2°/40 steps resulting in Δ(2θ) = 0.05°).

The two-dimensional raw data are evaluated to provide diffraction patterns corresponding to different detector heights ranging from 10 mm to 300 mm and variable detector height, accounting for vertical beam divergence effects (see figure 1). Thus, asymmetric broadenings at quite low and high scattering angles are overcome, while the full detector height in the medium 2θ regime can be used.

Various sample environmental devices enable the characterization of materials under special conditions: A rotatable tensile rig allows in-situ studies under tensile stress, compression stress or torsion while the load axis can be oriented with respect to the scattering plane. A potentiostat for charging/ discharging of Lithium ion batteries is available as well as a device to apply high electric fields on ferroelectrics. Additional apparatuses for the in-situ charging of catalysers with sorbents or the study of hydrogen storage materials under high deuterium pressures and elevated temperatures will be available in future.