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Two solution synthetic methods, sol-gel and a polymeric route, have been studied in order to obtain Ca 3 Co 4 O 9 misfit compounds with improved thermoelectric properties, compared to the classical solid state reaction. A comparison among the final products obtained by these different methods has been performed using DTA, TGA, FTIR X-ray diffraction, scanning electron microscopy, and thermoelectric characterizations. All the samples obtained by solution synthesis show a very significative reduction on the secondary phases content. As a consequence, an important decrease on the electrical resistivity values is produced, compared to the solid state prepared samples, leading to a relatively important power factor raise.

Textured Bi 2 Ca 2 Co 1.7 O x ceramic rods were obtained by Electrically Assisted Laser Floating Zone (EALFZ) technique. The polarity effects of an external current, applied during the laser floating zone growth, have been investigated.Microstructure and thermoelectric properties have been studied and correlated with the current polarity. An important improvement of power factor was obtained for samples grown with the positive pole connected to the seed. This result evidences the advantages of EALFZ technique as a potential method for obtaining high performance thermoelectric materials.