  We study the quark-hadron phase transition with the finite-size effects in
neutron stars. The finite-size effects should be, generally, taken into account
in the phase transition of multi-component system. The behavior of the phase
transition, however, strongly depends on the models for quark and hadron
matter, surface tension, neutrino fraction, and temperature. We find that, if
the surface tension is strong, the EOS becomes similar to the case of a Maxwell
construction for any hadron and/or quark model, though we adopt the Gibbs
conditions. We also find that the mass-radius relations for that EOS are
consistent with the observations, and our model is then applicable to realistic
astrophysical phenomena such as the thermal evolution of compact stars.
