DEBYE-SCHERRER DIFFRACTOMETER

Debye Scherrer System

Schematical view of our Debye-Scherrer system.


General Description

In contrast to standard instruments our Debye-Scherrer system enables measurements of very small amounts of sample material in thin capillaries or on glass fibres which are bathed in a highly focussed x-ray beam. Its also possible to collimate the primary beam to very small cross sections and to study local sections of larger samples. An elliptical Göbel mirror provides a focussed aund monochromatic beam (Kα1 and α2 are not separated) with high flux density and the appropriate cross section for this sample configuration. Due to the sample rotation (Debye-Scherrer or Gandolfi rotation) it is possible to obtain very good crystallite statistics important for coarse grained materials or very small amounts of sample material. A position sensitive detector (PSPC) with an angular acceptance angle of 10° additionally improves the crystallite statistics and also enables very short measuring times advantageous for in-situ studies. Our Debye-Scherrer system provides the opportunity of high-temperature measurements from RT up to 1200°C. The capillaries can be measured under ambient or non-ambient atmospheres (sealed off or controlled gas flow / micro-reactor with gas flow through capillary). The high temperature attachment works after an “oven” principle and has a temperature homogeneity along the capillary better than 3 K along the capillary in the investigated section (10-15 mm) and a temperature stability better than 0.5K.


Debye Scherrer System

Gandolfi Gandolfi Sample Stage

In addition to the simple Debye Scherrer sample rotation a combined rotation and precession (after Gandolfi) can be used to produce complete powder patterns even from polycrystalline particles or single crystals. This allows the materials identification of extremely small sample amounts.


GandolfiGandolfi

Debye Scherrer SystemDebye Scherrer System

Cross section of the high-temperature attachment and temperature profile along capillary axis.




Applications

Applications reach from phase identification of just a few crystalline particles or selected sections on parts with corrosions or surface layers (e.g. stents) to in-situ studies of phase transitions, thermal expansion and stress relaxation.

Example 1: In-situ high-temperature measurement (3D-image) of Quartz: phase transition of α- to β-Quartz at 573 °C and development of lattice constants evaluated with Rietveld Analysis.
Example 2: In-situ high-temperature measurement of Al/SiC Metal Matrix Composites: thermal expansion behaviour of SiC and Al and relaxation of phase specific micro residual stresses (Al: elasto-plastic behaviour, SiC: elastic behaviour)


Debye Scherrer Example

Example 1: In-situ high-temperature measurement (3D-image) of Quartz: phase transition of α- to β-Quartz at 573 °C and development of lattice constants evaluated with Rietveld Analysis.


Debye Scherrer Example

Example 2: In-situ high-temperature measurement of Al/SiC Metal Matrix Composites: thermal expansion behaviour of SiC and Al and relaxation of phase specific residual stresses (Al: elasto-plastic behaviour, SiC: elastic behaviour).