Thermoelectricity is crucial matter to use exhaust heat in our daily life. A metal oxide has been popular now besides metal compound and alloy. Unfortunately, oxide seems to be low electrical conductivity in general. However, an oxide has high thermoelectric power (Seebeck coefficient) and relatively low thermal conductivity. We study an oxide to decrease electrical resistivity during maintaining higher Seebeck coefficient and lower thermal conductivity. Fe_2O_3 was mostly investigated in substitution way to utilize metal such as Ti and Mn as compared with the other oxide such as ZnO for instances. Furthermore, in experiment we designed the actual materials based on ab-initio calculation. Fe_2O_3 was investigated in substitution method to utilize metal such as Ti in this study. As the results, non-substituted (or standard ) Fe_2O_3 has an energy gap of 3.5 eV to show 0.65 mV /K of Seebeck coefficient and10~(-1) OMEGA m . The energy gap of the substitution of Ti was calculated 2.3 eV and it resulted in the value of -0.35 mV/K and 10~(-3) OMEGA m. The effective charge of Fe was 1.88 and Ti was 2.42 ,meaning that the electrons seemed to move to Fe. Transport coefficient of thermoelectricity was also discussed associating with Onsager's equation
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