  We present model predictions for the Zr isotopic ratios produced by slow
neutron captures in C-rich asymptotic giant branch (AGB) stars of masses 1.25
to 4 Msun and metallicities Z=0.01 to 0.03, and compare them to data from
single meteoritic stardust silicon carbide (SiC) and high-density graphite
grains that condensed in the outflows of these stars. We compare predictions
produced using the Zr neutron-capture cross section from Bao et al. (2000) and
from n_TOF experiments at CERN, and present a new evaluation for the
neutron-capture cross section of the unstable isotope 95Zr, the branching point
leading to the production of 96Zr. The new cross sections generally presents an
improved match with the observational data, except for the 92Zr/94Zr ratios,
which are on average still substantially higher than predicted. The 96Zr/94Zr
ratios can be explained using our range of initial stellar masses, with the
most 96Zr-depleted grains originating from AGB stars of masses 1.8 - 3 Msun,
and the others from either lower or higher masses. The 90,91Zr/94Zr variations
measured in the grains are well reproduced by the range of stellar
metallicities considered here, which is the same needed to cover the Si
composition of the grains produced by the chemical evolution of the Galaxy. The
92Zr/94Zr versus 29Si/28Si positive correlation observed in the available data
suggests that stellar metallicity rather than rotation plays the major role in
covering the 90,91,92Zr/94Zr spread.
