Effect of platelet template seeds on microstructure and thermoelectric properties of Ca3Co4O9 ceramics

Influence of pressure and dwell time on pressure‐assisted sintering of calcium cobaltite

“…In literature, 10,16 κ of hot‐pressed Co349 decreases with rising measuring temperature. The κ over temperature curve is very similar for similar κ in different studies 10,16,35,36 and it can be fitted by the following equation κ = A ∙ e (‐ T /B) + C with absolute temperature T , and constants A, B, and C. . In this study, only κ of the reference was determined over the whole temperature range.…”

“…Thus, the ZT ab values presented in this paper are probably underestimated. When ZT ab is calculated using the extrapolated κ fit based on the κ over temperature curve of similar κ from literature, 35,36 the ZT values at 700°C as shown in Table 2 are reached ( ZT fit ). This results in ZT fit (700°C) of 0.2 for 2.5MPa, which is higher than published for hot‐pressed Co349 using κ ab 10,37 …”

“…All bold values were calculated using the extrapolated κ fit (700°C) according to κ fit = A ∙ e (‐ T /B) + C with A = 0.849, B = 512, C = 0.892 for 2.5 MPa derived from Shi et al 36 and A = 2.106, B = 205, C = 2.166 for 7.5 MPa 35 …”

Microstructure and thermoelectric performance of La‐doped (Ca0.9Ag0.1)3Co4O9/nano‐sized Ag composite ceramics

“…The peak of the lower binding energy located at 528.9 eV represented the Ca-O bonds/ Co-O bonds of lattice oxygen, the moderated peak located at 531.1 eV represented the adsorbed oxygen, such as the surface oxygen O 2− and O − , and the peak of higher binding energy located at 533.1 eV could be ascribed to the oxygen vacancy. [18][19][20] Table 2 shows the ratios of lattice oxygen, adsorbed oxygen, and oxygen vacancy. Due to the O 2− ions in the lattice was not easy to lose in the oxidizing atmosphere and the La 3+ ions reduced the concentration of oxygen vacancies, the oxygen vacancies was lower, ranging from 11.4% to 10.2%.…”

Effect of B4C addition on mechanical and electrical properties of Ca3Co4O9

“…However, their TE performances are lower than those determined in intermetallic materials. Consequently, most of the works published in this eld are dealing with the improvement of their TE performances through many different ways [7][8][9][10][11][12][13].…”