Document Type : Original Article


Professor, Dept. of Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea. Telephone no.: 82-2-2123-2853; Fax no.: 82-2-312- 5375.


Mesoporous ceramic materials have a structure containing nano-sized pores of 2~50
nm. Their pore size, pore distribution (regular/irregular, open/close), and pore shape
can be controlled easily during sol-gel procedure using evaporation induced self
assembly (EISA). During the EISA process, the pore structure of the films including
porosity, pore size, and pore distribution can be controlled by varying the surfactant
molar ratio. The existence of pores in the material grants distinctive properties such
as decreased dielectric constant from increased porosity and decreased thermal
conductivity from increasing phonon scattering. Therefore the mesoporous ceramic
thin films can be used in many applications such as thermal insulators, low dielectrics,
thermoelectrics, gas sensors, and so on.
Mesoporous titania and manganese-based films were prepared and their
thermoelectric properties were investigated. The efficiency of a thermoelectric is
determined by its dimensionless figure of merit, Z = S2
/ where S, , and  are the
Seebeck coefficient, electrical conductivity, and thermal conductivity, respectively.
Various experimental approaches including a control of pore structure and
introductions of dopants and nano-materials to enhance the thermoelectric property
are discussed. Through the approaches, an individual control of governing
parameters was carried out to control the thermal conductivity and electrical
conductivity of mesoporous oxides to maximize the thermoelectric property.