Study Of The High Temperature Thermoelectric Properties Of CdO Based Ceramics

The thermoelectric material as a functional material can convert between heat and electric energy, which has potential application in waste-heat power generation?refrigeration without Freon and so on. The oxide thermoelectric materials have some unique advantages such as good chemical and thermal stability in high temperature oxidizing atmosphere, thus, more and more attention are gained. Cadmium Oxide?Cd O? as an n-type transparent conducting oxides?TCO? also has a good higher-temperature thermoelectric performance, which may be applied. In this thesis, we prepared CdO-based ceramics by solid-state reactions method and investigated their performance. The main conclusions are as follow:1,We prepared CdO-based polycrystalline bulk samples with doping Al by traditional solid-state reactions method, to regulate carrier concentration?n? with doping higher valence ion Al³⁺,then investigate electric transport and thermoelectric performance. The results show that Al³⁺ doping improved power factor?S²??, so the total thermal conductivity??? was, due to the the increase in electron thermal conductivity. Thus, thermoelectric figure of merit didn't get better.2, To investigate electric and heat transport by doping equivalent ion Sr²⁺.For one thing carrier concentration increased for the difference of electron affinity, which improved both the resistivity??? and the Seebeck coefficient?S?. Then the power factor?S²?? decreased. For another, both the electron and phonon thermal conductivity decreased. As a result, the thermoelectric figure of merit was improved significantly. the sample:Cd0.97Sr0.03 O has the high ZT of 0.4,at 1000 K.3, We expected to regulate both the electric and heat transport by doping CuSO₄·5H₂O. CuSO₄·5H₂O at high temperature pyrolyzes into Cu2+ ion and SO₃, which can optimize both the electron transport and phonon transport better. The results show that Cd0.995Cu0.005 O sample has the high ZT of 0.41,at 1000 K.