Oseroff et al. measured the specific heat (Cp) of Zn, Ni and Mn-doped CuGeO3 and found a peak at the cusp temperature . Since a peak in the specific heat should be absent for the spin-glass transition , but present for Néel order, they proposed a Néel ordered ground state for the doped materials.
Recent neutron scattering measurements of single crystalline (Cu1-xZnx)GeO3 (x=3.4 %) showed the existence of antiferromagnetic Bragg reflections ; this result directly indicates the Néel order. The size of the ordered moments was obtained as , which is less than half of what was observed in a Néel ordered spin chain ( for KCuF3 ).
Si-doped systems Cu(Ge1-ySiy)O3 were investigated by Renard et al. with susceptibility and 63Cu-NMR measurements . The spin Peierls transition disappeared at Si concentration % and a Néel ground state appeared at %. The phase diagram for the Si-doped compounds is similar to that of the Zn-doped systems (Fig.53), with the -maximum concentration shifted from x=4% to y=2% for the Si doping.
Poirier et al. measured elastic constants in high magnetic fields and
obtained an phase diagram for a Si 0.7% doped system
. They found that the overall structure of the
phase diagram (Fig.54) was similar
to the general phase diagram of spin Peierls systems
(Fig.51), except that the spin Peierls phase (SP)
is split to a SP-phase and a Néel ordered phase (AF).
Since a magnetic ordered phase is expected from previous measurements, SR is a good probe for further investigations of the Zn/Si-doped systems. Previously, Tchernyshyov et al.  and García-Muñoz et al.  performed SR measurements on Zn 4% samples and found a spin-glass-like muon spin relaxation. In the next section, more extensive SR studies of Zn/Si-doped systems [(Cu1-xZnx)(Ge1-ySiy)O3; x=2, 4, 8 %, and ], are presented in addition to the SR results from the nominally pure CuGeO3.