PhD Thesis_RuiMSMartins.pdf - RUN UNL

In-situ XRD studies during growth of Ni-Ti SMA films and their complementary ex-situ characterization
(a)
(b)
Fig. 2.4: Six-circle diffractometer in the MRH of ROBL; (a) view of the χ-circle (Eulerian
cradle with inner diameter of 400 mm) with the x-y-z slide mounted directly on the
azimuthal ϕ-circle (front view: detector side), (b) scheme of the diffractometer with
identification of the axes (view from back: beam direction).
In order to follow in situ the film growth and post-deposition annealing, Matz et al.
[58] have designed a sputtering chamber that fits into the Huber six-circle diffractometer.
Since the diffractometer is used as a multi-purpose instrument for many other experiments,
the chamber has to be removed always after the beamtimes dedicated to this type of studies.
During the period of this thesis work, a new chamber was built by Schell et al. [156] and was
also tested and used in the deposition of the Ni-Ti films. The results were reproducible with
both chambers and the main advantage of the new chamber for this work are the enlarged
windows allowing the study of a higher number of Bragg peaks of the phases present in the
sample. The “old” set-up (equipped with Kapton-capped flanges as X-ray entrance and exit
windows) and the “new” set-up (sealed with Be foils) are described below.
The chambers have been designed to be mounted on the ϕ-circle and limited in weight
to 15 kg in order to guarantee the high precision of the goniometer settings of 0.001°. The
other geometrical limitation results from the χ-circle perpendicular to the ϕ-circle. The χ-
circle has an inner diameter of 400 mm but is located 85 mm off-centre of the ϕ-circle.
Taking those limitations into account one can use all existing instalments/equipment at the
diffractometer like detectors, slits, collimators, and filter units without additional
modifications. The Eulerian cradle is fitted to the θ circle and with an identical rotation axis
Chapter 2 – Experimental Details 81