[IEEE ICT'03. 22nd International Conference on Thermoelectrics - La Grande Motte, France (17-21 Aug. 2003)] Proceedings ICT'03. 22nd International Conference on Thermoelectrics (IEEE Cat. No.03TH8726) - Sintering process and nonstoichiometry of NaCo/sub 2/O/sub 4/ layered thermoelectric oxide