Preparation and thermoelectric properties of Al and Ti co-doped non-stoichiometric TiAl0.02O1.78 under different synthesis pressures

Abstract Nonstoichiometric TiAl0.02O1.78 materials were synthesized by high temperature and high pressure (HPHT) under different synthesis pressures (3.0 GPa, 4.0 GPa and 5.0 GPa). The purpose of combined Al and Ti doping is to improve the electrical properties of the material. And the thermal conductivity was inhibited by the HPHT process. Using the X-ray diffraction to study the phase structure. Using the transmission electron microscope (TEM) to study the microstructure and scanning electron microscope (SEM) to study morphology. Also, the thermoelectric properties were studied with respect to variable temperatures at atmospheric pressure and the effects of pressure were studied relative to the sample energy gap width. It was determined that as synthesis pressure increases, the energy gap width decreases, which aids in the resistivity decrease of the sample. When the test temperature was 973 K at atmospheric pressure and the synthesis pressure of samples was 5.0 GPa, the zT value of the sample reached a maximum of 0.20.