Effects of post-annealing on thermoelectric properties of p-type CoSb3 grown by the vertical Bridgman method

Thermoelectric properties of undoped p-type CoSb3 prepared by vertical Bridgman crystal growth and spark plasma sintering

“…The samples annealed for more than 5 h demonstrate that the observed Seebeck coefficient has a high value in the relatively lower temperature range from 370 to 600 K, although CoSb 3 sintered in a conventional manner exhibits a maximum Seebeck coefficient at 600-750 K [7][8][9][10][11][12][13][14]. Compared with the expected Seebeck coefficient of ∼190 V/K for the present carrier concentration [15], the observed values are higher in the lower temperature region.…”

“…We have fabricated bulk CoSb 3 using the conventional vertical Bridgman method [11][12][13]. While single crystallike material was obtained with a growth rate of 0.4 mm/h, at a faster rate of 2.8 mm/h grains of CoSb 3 crystals surrounded by residual metallic Sb were grown [11].…”

“…The residual Sb caused the electrical conductivity to be increased and the Seebeck coefficient to be decreased. We found that the residual Sb could be removed by post-annealing, leading to a significant increase in the Seebeck coefficient, but these samples also exhibited a much decreased electrical conductivity [12]. To improve the figure of merit, we applied a post-annealing process and deposited a highly conductive metal (Au) on the post-annealed samples.…”

Czochralski crystal growth of Zn2Te3O8

“…Some researchers were able to pull single crystals at incongruent points [11]. Other workers reported the growth of single crystals from non-stoichiometric melts [12,13], while others grew multiphase semiconductor crystals at the peritectic phase transformation [14].…”

ZnTeO 3 crystal growth by a modified Bridgman technique

“…This mole percentage was also selected because it produced the required crystal. When cooled down, the 40:60 goes through a peritectic transformation and forms more than one phase, but single crystals can still be grown at this transformation [14,15]. Table 1 shows several mole percentages of ZnO-TeO 2 powders that were tested for growth.…”