双钙钛矿(Y,Gd,Eu)BaCo_(2)O_(5+δ)的制备和氧敏性

Synthesis and oxygen sensing properties of double perovskite(Y,Gd,Eu)BaCo_(2)O_(5+δ)

双钙钛矿钴氧化物因高的电导率和快的氧离子扩散能力在固态燃烧电池阴极和氧敏传感器中具有潜在的应用前景.RBaCo_(2)O_(5+δ)(R=Y,Gd,Eu)陶瓷的电输运性质表明从室温到700℃,发生半导体金属转变,且电导率随着离子半径的增加而增大.其中,EuBaCo_(2)O_(5+δ)的电导率高达850 S/cm,远高于阴极材料的电导率需求(>100 S/cm).在600℃,当从O_(2)切换到N_(2)时,(Gd,Eu)BaCo_(2)O_(5+δ)陶瓷的电阻率灵敏度高达130%,响应时间约为3000 s,而YBaCo_(2)O_(5+δ)陶瓷的电阻率灵敏度仅约60%,响应时间仅约600 s;当从N_(2)切换到O_(2)时,(Gd,Eu)BaCo_(2)O_(5+δ)陶瓷的恢复时间约为40 s,而YBaCo_(2)O_(5+δ)陶瓷的恢复时间约为10 s.随着温度的升高,氧脱附速率增加,而氧吸附速率几乎不变.

Double perovskite cobalt oxides(Y,Gd,Eu)BaCo_(2)O_(5+δ)have a potential application prospect in the cathode of solid-state fuel cells and oxygen sensors due to their high conductivity and fast oxygen diffusion ability.The electric transport properties of(Y,Gd,Eu)BaCo_(2)O_(5+δ)ceramics show that they have semiconductor-metal transformation from room temperature to 700℃,and their conductivities increase with the increase of ionic radius.The conductivity of EuBaCo_(2)O_(5+δ)is as high as 850 S/cm,much higher than that of the cathode materials of solid fuel cell(>100 S/cm).At 600℃,when the gaseous atmosphere is shifted from O_(2) to N_(2),the resistivity sensitivity of(Gd,Eu)BaCo_(2)O_(5+δ)ceramics is 130%,the response time is about 3000 s,while the resistivity sensitivity of YBaCo_(2)O_(5+δ)is only about 60%,the response time is only about 600 s.When gaseous atmosphere is shifted from N_(2) to O_(2),the recovery time of(Gd,Eu)BaCo_(2)O_(5+δ)is about 40 s,and the recovery time of YBaCo_(2)O_(5+δ)ceramic is about 10 s.With the increase of temperature,oxygen desorption rate increases,and oxygen adsorption rate is almost unchanged.