The influence of Ba-excess and liquid phase sintering with SiO2 on the electrical conduction and microstructure in PTCR BaTiO3 has been investigated. Dense (95-96%), small grain (5-10 mu m) PTCR materials were obtained in Ba-excess (Ba/Ti = 1.006) BaTiO3. The materials exhibit low room temperature resistivity rho(RT) (10(0)-10(2) Omega . cm) and high PTCR respond (more than 5 orders). Solid state sintering was found to inhabit the semiconducting and PTCR behavior in Ba-excess materials. Liquid phase sintering, using SiO2 in the Ba-excess BaTiO3, resulted in low rho(RT) and significant PTCR response. Through domain observation, interior "Polaron deficient zones" were found in samples which exhibit limited liquid phase sintering, leading to non-uniform directional domains and low charge carrier mobility. Proper control of the SiO2 concentration was found critical for obtaining uniform directional domain microstructures and low rho(RT).