Secondary phase Bi_(2)O_(3),which could promote the sintering densification of ceramics,was used to prepare(Ca_(0.85)Ag_(0.1)La_(0.05))_(3)Co_(4)O_(9) thermoelectric ceramics.The mechanism of liquidphase sintering pr...Secondary phase Bi_(2)O_(3),which could promote the sintering densification of ceramics,was used to prepare(Ca_(0.85)Ag_(0.1)La_(0.05))_(3)Co_(4)O_(9) thermoelectric ceramics.The mechanism of liquidphase sintering process revealed that the diffusion rate of particles originated from the dissolvedeprecipitated processing for samples and suppressed the coarsening of grain growth.The effects of Bi_(2)O_(3) on the microstructure and thermoelectric properties were investigated.The results showed that the relative density of samples increased from 92.1% to 95.5% through the liquidphase sintering mechanism.The band gaps were tuned and it had the profound impact on the transport of charge carriers.Electrical resistivity decreased while Seebeck coefficient increased from 110 mV/K to 190 mV/K with increasing Bi_(2)O_(3).Furthermore,the peak ZT value of 0.25 for 6 wt% Bi_(2)O_(3) sample at 1073 K was obtained,resulting from low thermal conductivity of 0.92 W/(m·K).It suggests that Bi_(2)O_(3) additive can dramatically improve the thermoelectric properties of Ca_(3)Co_(4)O_(9).展开更多
基金supported by the National Natural Science Foundation of China(No.51672219,5171101743,51702259)Excellent Youth Fund of the National Natural Science Foundation of China(No.11722219)+3 种基金Foundation of National High Technology Research and Development Program(No.2015AA0172)Fundamental Research Fund for the Central Universities(No.G2016KY0302)the“111”Project(No.B08040)the Research Foundation of the State Key Laboratory of Solidification Processing(NWPU),China(No.137-QP-2015).
文摘Secondary phase Bi_(2)O_(3),which could promote the sintering densification of ceramics,was used to prepare(Ca_(0.85)Ag_(0.1)La_(0.05))_(3)Co_(4)O_(9) thermoelectric ceramics.The mechanism of liquidphase sintering process revealed that the diffusion rate of particles originated from the dissolvedeprecipitated processing for samples and suppressed the coarsening of grain growth.The effects of Bi_(2)O_(3) on the microstructure and thermoelectric properties were investigated.The results showed that the relative density of samples increased from 92.1% to 95.5% through the liquidphase sintering mechanism.The band gaps were tuned and it had the profound impact on the transport of charge carriers.Electrical resistivity decreased while Seebeck coefficient increased from 110 mV/K to 190 mV/K with increasing Bi_(2)O_(3).Furthermore,the peak ZT value of 0.25 for 6 wt% Bi_(2)O_(3) sample at 1073 K was obtained,resulting from low thermal conductivity of 0.92 W/(m·K).It suggests that Bi_(2)O_(3) additive can dramatically improve the thermoelectric properties of Ca_(3)Co_(4)O_(9).
