BaTi1-xCoxO3 ceramics (x = 0.05 approximate to 0.25) have been synthesized with the solid state method and the Co-doping samples were formed hexagonal structure with x < 0.25. The XPS spectra show the two Co(2+)2p(3/2) and Co(2+)2p(1/2) peaks in full doping range, which indicates hexagonal BaTi1-xCoxO3 are stable by Co2+, not Co3+-ion. Although the radius of Co2+-ion is larger than the radius of Ti4+-ion, the volume of unit cell is still decreasing with Co concentration increasing due to oxygen vacancy increasing, which can induce the hydrostatic pressure in this system. The Qxf value and K value are both decreasing with Co-doping level increasing due to hydrostatic pressure increasing.
