Why do metals have different Seebeck coefficients?
We define Seebeck coefficient as the potential difference developed to the temperature gradient applied. For metal the charge carriers are more and hence applying a temperature gradient should lead to diffusion of more charge carriers on the other side and hence potential difference should be more.
What is the value of Seebeck coefficient?
The Seebeck coefficient of platinum itself is approximately −5 μV/K at room temperature, and so the values listed below should be compensated accordingly. For example, the Seebeck coefficients of Cu, Ag, Au are 1.5 μV/K, and of Al −1.5 μV/K.
What does Seebeck coefficient depend on?
The Seebeck coefficient and electrical conductivity strongly depend on the Fermi level, which in turn depends on the carrier concentration, carrier effective mass, and temperature. In theoretical formulations, it is convenient to express the thermoelectric transport coefficients in terms of the Fermi energy.
How is Seebeck coefficient measured?
Seebeck coefficient is measured by measuring the upper and lower temperatures T1 and T2 with the thermocouples pressed against the side of the sample, followed by measurement of thermal electromotive force dE between the same wires on one side of the thermocouple.
Why Seebeck coefficient is inversely proportional to carrier concentration?
The electrical conductivity is proportional to carrier density and mobility (=n.q.u, where n is carrier density n-p), so that the S will decrease with increase of charge carrier concentration. Since the Seebeck is inversely proportional to the carrier density. n increases, Seebeck decreases as you said.
How do you increase Seebeck coefficient?
Lowering the charge carrier concentration can increase the Seebeck coefficient while decreasing the conductivity.
Does the Seebeck coefficient vary with temperature?
Here, we report the results of our experimental work on the thermoelectric properties of the undoped polycrystalline ZnO thin films. It is shown that as the temperature increases, the Seebeck coefficient of ZnO increases in absolute value.