Development of Oxygen Semipermeable Membrane Using Mixed Conductive Perovskite-Type Oxide

For the development of an oxygen semipermeable membrane using mixed conductive perovskite-type oxides，investigated were the material searching，the evaluation of mixed conductivity and the fabrication of pracical device.21sorts of LnCoO_3based perovskite-type oxides were prepared and their oxygen semipermeabilities were examined systematcally with regard to a partial substitution of A and B site cations.Among them，La_&lt；0.6&gt；Sr_&lt；0.4&gt；Co_&lt；0.8&gt；B‘_&lt；0.2&gt；O_3(B’=Cu，Ni)，Gd_&lt；0.6&gt；Sr_&lt；0.4&gt；CoO_3，La_&lt；0.2&gt；Sr_&lt；0.8&gt；Co_&lt；0.8&gt；Fe_&lt；0.8&gt；Fe_&lt；0.8&gt；O_3and Gd_&lt；0.2&gt；Ba_&lt；0.8&gt；Co_&lt；0.7&gt；Cu_&lt；0.2&gt；Fe_&lt；0.1&gt；O_3showed an excellent oxygen semipermeability and they were found to be suitable for the oxygen semipermeable membrane.By the way，La_&lt；1-x&gt；Sr_XCo_&lt；1-r&gt；Fe_yO_3was found to show a good mixed conductivity by means of four probe ionic dc and ordinary four-probe dc techniques.La_&lt；0.6&gt；Sr_&lt；0.4&gt；CoO_3(LSCO)was used for the fabrication of practical device。Of the several methods attempted，sintering of a compact of LSCO pow…More der which was calcined at 1400℃and sieved to 44-74 mum gave discs having a high air permeability through penetrating channels consisting of a network of intergranular pores.The disc appeared to be suitable as a porous support on which oxygen semipermeable thin membrane was formed.The preparation of dense thin membrane on the porous support was achieved by using a spray deposition-technique consisted of a repetition of sprying an ethanol suspension of fine LSCO particles and sintering for 1h in air。Under the condition of 2.0 mg/cm^2of LSCO per one spray and 1400°C for sintering，the open pores of porous support were progressively covered with the deposited layer with repeating the procedure and the almost completely dense overlayer of about15mum thickness was obtained after repetition by four times。The thin film device fabricated by above-mentioned procedure showed a higher rate of oxygen semipermeation than that of the dense sintered disc with the thickness of 1.5毫米，although the rate was lower than was expected。Control of the chemical composition at the film surface as well as the dispersion of open pores of the substrate was suggested to be important for further revisions。Less：Less

For the development of an oxygen semipermeable membrane using mixed conductive perovskite-type oxides, investigated were the material searching, the evaluation of mixed conductivity and the fabrication of pracical device. 21 sorts of LnCoO_3 based perovskite-type oxides were prepared and their oxygen semipermeabilities were examined systematcally with regard to a partial substitution of A and B site cations. Among them, La_<0.6>Sr_<0.4>Co_<0.8>B'_<0.2>O_3 (B'=Cu, Ni), Gd_<0.6>Sr_<0.4>CoO_3, La_<0.2>Sr_<0.8>Co_<0.8>Fe_<0.8>O_3 and Gd_<0.2>Ba_<0.8>Co_<0.7>Cu_<0.2>Fe_<0.1>O_3 showed an excellent oxygen semipermeability and they were found to be suitable for the oxygen semipermeable membrane. By the way, La_<1-x>Sr_XCo_<1-r>Fe_yO_3 was found to show a good mixed conductivity by means of four probe ionic dc and ordinary four-probe dc techniques. La_<0.6>Sr_<0.4>CoO_3 (LSCO) was used for the fabrication of practical device. Of the several methods attempted, sintering of a compact of LSCO pow … More der which was calcined at 1400 ゜C and sieved to 44-74 mum gave discs having a high air permeability through penetrating channels consisting of a network of intergranular pores. The disc appeared to be suitable as a porous support on which oxygen semipermeable thin membrane was formed. The preparation of dense thin membrane on the porous support was achieved by using a spray deposition-technique consisted of a repetition of sprying an ethanol suspension of fine LSCO particles and sintering for 1h in air. Under the condition of 2.0 mg/cm^2 of LSCO per one spray and 1400 ゜C for sintering, the open pores of porous support were progressively covered with the deposited layer with repeating the procedure and the almost completely dense overlayer of about 15 mum thickness was obtained after repetition by four times. The thin film device fabricated by above-mentioned procedure showed a higher rate of oxygen semipermeation than that of the dense sintered disc with the thickness of 1.5 mm, although the rate was lower than was expected. Control of the chemical composition at the film surface as well as the dispersion of open pores of the substrate was suggested to be important for further revisions. Less