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Abstract:
Complete miscibility of the intermetallic phases (IPs) SrGa2 and BaGa2
forming the solid solution Sr1-xBaxGa2 is shown by means of X-ray
diffraction, thermoanalytical and metallographic studies. Regarding the
distances of Sr/Ba sites versus substitution degree, a model of isolated
substitution centres (ISC) for up to 10% cation substitution is explored
to study the influence on the Ga bonding situation. A combined
application of NMR spectroscopy and quantum mechanical (QM) calculations
proves the electric field gradient (EFG) to be a sensitive measure of
different bonding situations. The experimental resolution is boosted by
orientation-dependent NMR on magnetically aligned powder samples,
revealing in first approximation two different Ga species in the ISC
regimes. EFG calculations using superlattice structures within periodic
boundary conditions are in fair agreement with the NMR spectroscopy data
and are discussed in detail regarding their application on disordered
IPs.
