Thermoelectric properties of Bi2Sr2Co2Ox polycrystalline materials

Abstract

Bi 2 Sr 2 Co 2 O 9 (BC-2202) polycrystalline materials with a layered structure have been prepared by partial melting. The chemical compositions of the samples are Bi2Sr2Co2Ox (2202), Bi1.8Sr2Co2Ox (Bi-1.8), and Bi2Sr1.8Co2Ox (Sr-1.8). All three samples are p-type conductors. The electric properties, namely, the Seebeck coefficient (S) and electric resistivity (ρ), of the samples are dependent on chemical composition. The S values increase with temperature at T>673 K and, at 973 K, reach 100, 110, and 150 μV K−1 for the 2202, the Bi-1.8, and the Sr-1.8 samples, respectively. Thermal conductivity (κ) for all samples is lower than for ordinary conducting oxides. The figure of merit (Z) increases with temperature for all samples. Z values at 973 K are 0.77×10−4, 0.61×10−4, and 2.0×10−4 K−1 for the 2202, Bi-1.8, and Sr-1.8 samples, respectively. The thermoelectric properties depend on the chemical composition of the BC-2202 phase. The BC-2202 material thus appears to be a promising thermoelectric material due to its high performance at high temperature (∼1000 K).

Transport properties of the layered Rh oxide K0.49RhO2

“…Equation (4) shows that the carrier concentration dependence of R H is almost independent of y where the carrier concentration is nearly half (y ∼ 0.5), and accordingly the four-times difference in dR H /dT between Na 0.68 CoO 2 and K 0.49 RhO 2 is ascribed to the difference in t.…”

“…Since the discovery of large thermopower with low resistivity in Na x CoO 2 [1], Co oxides with the CdI 2 -type CoO 2 layer such as Ca-Co-O and Bi-Sr-Co-O have been studied as thermoelectric materials [2,3,4,5,6]. These materials have large thermopower comparable to conventional thermoelectric materials, which is considered to be due to the degeneracy of spins and orbitals [7].…”

Thermoelectric properties of Bi2Sr2Co2O9 whiskers under hydrostatic pressure

“…7,8 Recently, it was discovered that oxide materials can have reasonably high values of S ͑100 V/K͒ at high temperatures, making them potentially useful for power generation applications. The thermoelectric properties of polycrystalline samples Bi 2 Sr 2 Co 2 O 9 ͑BC-222͒ were found to be superior to most other oxides 9 and singlecrystal BC-222 whiskers were found to have a power factor (S 2 ) 5-7 times higher than that of the polycrystalline BC-222 samples. In this letter, we extend the previous studies and investigate the thermoelectric properties BC-222 whiskers under hydrostatic pressure.…”

High Temperature Integrated Thermoelectric Ststem and Materials

“…The expectation was that they will exhibit n-type behavior. [16][17][18][19][20]. Literature reports tend to suggest it might be possible to sinter these Mn and Co based compositions in air to yield high electrical conductivities to give high ZTs for high temperature thermoelectric application.…”

“…The composition of 1.0 SrO -1.03x0.8 Ti02 -1.03x0.2 Nb02.5 as discussed in Task 4 work was chosen as the n-type thermoelectric leg. Physical and thermoelectric properties of this material as shown in Table 10, Figure 17, 18,19,20, and 21 in previous sections were chosen as design inputs. As a candidate p-type material has yet to be developed, it was assumed that the p-type legs have properties similar to n-type legs.…”