  We calculate the linear evolution for a class of mixed dark matter models,
where the hot component derives from the decay of a heavier particle (CntHDM
models). These models differ from ordinary mixed models based on massive
neutrinos (CHDM models), for which the hot component has a phase space
distribution which derives from a thermal one. In CntHDM models the density of
the hot component and the derelativisation redshift of its quanta are
indipendent parameters.
  In this work we provide the spectra for a number of CntHDM models, and
compare them with CDM and CHDM spectra.
  If PQ symmetry and SUSY simultaneously hold, the lightest standard neutralino
can be expected to decay into axino and photon.
  We briefly summarise the features of this particle model which gives rise to
the cosmological framework discussed here, as a fairly generic consequence.
Other frameworks which lead to similar models are also briefly discussed.
