Single crystal growth of homologous compounds in the ZnO-In/sub 2/O/sub 3/ system and thermoelectric properties

Single crystals of (ZnO)/sub 5/In/sub 2/O/sub 3/ were grown by a normal flux method, using PbF/sub 2/ as a flux, and the resulting flaky single crystals were very thin along the c-axis. Single crystal quality was evaluated by XRD, TEM, and SEM. Band gap energy of single crystal was optically determined. The inplane electrical conductivity (/spl sigma/), and Seebeck coefficient (cc) were measured in the temperature range of 300 K to 1200 K and 500 K to 1200 K in air, respectively. The electrical conductivity of a single crystal was found to be 2/spl times/10/sup 6/ Sm/sup -1/ at room temperature, it decreased with increasing temperature and attained a value of 5/spl times/10/sup 5/ Sm/sup -1/ at 1200 K. Anisotropy of two orders of magnitude in electrical conductivity was first clarified. Seebeck coefficient was determined to be -9.6 /spl mu/VK/sup -1/ at 500 K and -31.6 /spl mu/VK/sup -1/ at 1200 K. The estimated power factor was about 1.4/spl times/10/sup -4/ Wm/sup -1/K/sup -2/ at 500 K. This factor increased with temperature, and reached the value of 5.3/spl times/10/sup -4/ Wm/sup -1/K/sup -2/ at 1200 K.