Moessbauer studies of ZnCrsub(2x)Gasub(2-2x)O4 spinel solid solutions: a cluster spin glass for 0.6 <approx. x <approx. 0.85

Moessbauer studies of topologically frustrated ZnCrsub(2x)Gasub(2-2x)O4 system (0.6 <= x <= 1) are performed. Almost all the spectra consist of a superposition of a paramagnetic doublet and an enlarged magnetic hyperfine pattern. Two models are used to fit the spectra, a static hyperfine field distribution method and a superparamagnetic type relaxation simulation method. In the composition range 0.6 <= x <= 0.85, for which spin glass behaviour has been evidenced, only the second model gives coherent results rather in agreement to a dynamic non equilibrium process with a progressive freezing of cluster moment. (Auth.)