  The ferromagnetic phase of an Ising model in d=3, with any amount of quenched
antiferromagnetic bond randomness, is shown to undergo a transition to a
spin-glass phase under sufficient quenched bond dilution. This general result,
demonstrated here with the numerically exact renormalization-group solution of
a d=3 hierarchical lattice, is expected to hold true generally, for the cubic
lattice and for quenched site dilution. Conversely, in the
ferromagnetic-spinglass-antiferromagnetic phase diagram, the spin-glass phase
expands under quenched dilution at the expense of the ferromagnetic and
antiferromagnetic phases. In the ferro-spinglass phase transition induced by
quenched dilution reentrance is seen, as previously found for the
ferro-spinglass transition induced by increasing the antiferromagnetic bond
concentration.
