  We have investigated the Pb-substitution effect on the superconductivity of
NaCl-type In1-xPbxTe samples obtained using high-pressure synthesis.
Polycrystalline samples with x = 0-0.8 were obtained, and the lattice parameter
systematically increased by Pb substitution. The superconducting transition
temperature (Tc ~3 K for x = 0) increased to 5.3 K (for x = 0.4) by Pb
substitutions. According to the comparison of the electronic states between
NaCl-type InTe and PbTe, we consider that the Pb substitution increases
electron carriers. Possible mechanisms of the enhancement of Tc in this system
have been discussed on the basis of conventional pairing mechanism and the
possibility of the relation to the valence-skipping state of In.
