Synthesis of mesoporous Lainf0.7/infSrinf0.3/infMnOinf3/inf thin films for thermoelectric materials

Mesoporous Lainf0.7/infSrinf0.3/infMnOinf3/inf (LSMO) films were prepared to determine the potential for applications within thermoelectric materials. The mesoporous structure induces a decrease in thermal conductivity due to increased phonon scattering, and an increase in the Seebeck coefficient due to an increased specific surface area. An increase in surface area induces an increase in oxygen vacancies which results in band narrowing and a filled Mn 3d state with the electron-combined oxygen. As a result, the mesoporous LSMO film showed an increased Seebeck coefficient and a reduced thermal conductivity but, in addition, showed a greatly increased electrical resistivity with the filled Mn 3d states. This abnormally large increase in electrical resistivity resulted in a reduced figure of merit for the LSMO film even after the introduction of a mesoporous structure. An effect of the applied mesoporous structure on the thermoelectric properties was shown to be varied due to a change in the amount of oxygen defects in the LSMO with a perovskite structure.