  The influence of lattice strain and Mg vacancies on the superconducting
properties of MgB2 samples has been investigated. High quality samples with
sharp superconducting transitions were synthesized. The variation in lattice
strain and Mg vacancy concentrations were obtained by varying the synthesis
conditions. It was found that high strain (~1%) and the presence of Mg
vacancies (~ 5 %) resulted in lowering the Tc by only 2 K.
