Ti掺杂对Ba_(0.5)Sr_(0.5)Co^(0.8)Fe_(0.2)O_(3-δ)陶瓷透氧膜性能的影响

Effect of TiDoping on Performance of Ba_(0.5)Sr_(0.5)Co^(0.8)Fe_(0.2)O_(3-δ)Ceramic Membrane for Oxygen Separation

采用EDTA-柠檬酸双络合法合成了Ba_(0.5)Sr_(0.5)(Co^(0.8)Fe_(0.2))_(1-x)Ti_(x)O_(3-δ)(x=0~0.2)粉体,并通过干压成型和高温烧成制备了片状致密陶瓷膜。研究了钙钛矿结构中B位Ti掺杂量对合成粉体物相结构和相应的膜的微观结构、电导特性、氧渗透性能和热膨胀性能等的影响。结果表明,5~20 mol/%Ti掺杂Ba_(0.5)Sr_(0.5)Co^(0.8)Fe_(0.2)O_(3-δ)(BSCF)与未掺杂BSCF一样都呈现单一立方钙钛矿结构。不同Ti含量BSCF陶瓷膜经1150℃保温5 h烧成后都可获得致密的微观结构。制备的混合导体陶瓷膜的电导率、氧渗透通量和热膨胀系数都随着Ti含量增加而不断减小,但膜的高温长期稳定性却明显提高。其中,10 mol/%Ti掺杂BSCF膜在800℃工作100 h后的氧渗透通量保持在0.87 mL·cm^(-2)·min^(-1)左右,而未改性膜却衰减至低于0.70 mL·cm^(-2)·min^(-1)。

Ba_(0.5)Sr_(0.5)(Co^(0.8)Fe_(0.2))_(1-x)Ti_(x)O_(3-δ)(x=0~0.2) powdersweresynthesized by the EDTA-citric acid double complex method.The corresponding disk membranes were fabricated by dry pressingand subsequent high-temperature sintering.The effects of Ti doping in the B-site of perovskite structure on the phase structure of obtained powders and the microstructure,conductivity,oxygen permeate flux and thermal expansion coefficient of prepared membranes were investigated.Results show that both undoped Ba_(0.5)Sr_(0.5)Co^(0.8)Fe_(0.2)O_(3-δ)(BSCF)and 5~20 mol/%Ti doped BSCF possess the cubic perovskite structure.A dense microstructure can be achieved for all the membranes sintered at 1150℃ for 5 h.The increasing of Ti content led to the decreasing of total conductivity,oxygen permeate flux and thermal expansion coefficient.However,the long-term stability at high temperature could be increased greatly for BSCF-based ceramic membranes with the doping of Ti.The 10 mol/%Ti doped BSCF membrane exhibited a relative stable oxygen permeate flux of about 0.87 mL·cm^(-2)·min^(-1)after run for 100 h at 800℃,while the flux of undoped membranes degraded to less than 0.70 mL·cm^(-2)·min^(-1).