BaCe_ (1-x) M_xO_ (3-α) (M = Ca, Yb) synthesis, and application of electrical conductivity in the temperature

Title: BaCe_ (1-x) M_xO_ (3-α) (M = Ca, Yb) synthesis, and application of electrical conductivity in the temperature
　　Author: Liu Jinwei
　　Degree awarded: Suzhou University
　　Keywords: BaCeO_3;; microemulsion;; proton conductor;; atmospheric ammonia;; hydrogenation of organic matter
　　Summary:
　　BaCeO_3 sub-conductor substrate is an important class of functional materials in solid oxide fuel cell (SOFC), hydrogen sensor, steam electrolyzer, hydrogen separation and purification, atmospheric ammonia, nuclear fusion of hydrogen isotopes in the rare earth magnets reactor exhaust gas recycling electrochemical devices and membrane reactors has important application value and broad application prospects.
　　BaCeO_3 usually trivalent ion-doped rare earth ions and Ca ~ (2), relative to the Ca ~ (2) doped with trivalent rare earth ions have a higher conductivity, but the Ca-rich low-cost elements, the Ce-bit mixed in BaCeO_3 Ca for the cost of industrial applications is important. But so far, the BaCeO_3 CaO-doped ceramics research, there are two deficiencies: (1) the traditional preparation of high temperature solid proton conductor doped with CaO in BaCeO_3 calcining and sintering temperature is usually up to 1400 ° C and 1665 ° C, high temperature heat treatment produces high energy consumption and higher demands on the equipment issue. (2) Iwahara group of Ca-doped BaCeO_3 at 600 ~ 1000 ° C the proton conductivity, Slade group only uses water vapor concentration cell method of Ca-doped BaCeO_3 at 400 ~ 800 ° C under proton conductivity, but so far for the 300 ~ 600 ° C the proton conductivity is still not fully studied, and no atmospheric ammonia in the application report. In addition, BaCeO_3 organic substrate used in catalytic synthesis of sub-conductors few reports. To this end, this paper conducted a study to address these issues.
　　The paper's research work and results are as follows:
　　1 was synthesized using microemulsion BaCe1-xCaxO_3-α (x = 0.05, 0.10, 0.15, 0.20) ceramic samples of the powder series, the 1050 ° C 1500 ° C calcined and sintered dense ceramic samples had the system, calcining and sintering temperatures than traditional high-temperature solid-phase method to reduce the 350 ° C and 165 ° C. In order to compare the impact of different methods, also used sol - gel synthesis of x = 0.10 sample. Microstructure of the sample formation process and structure of the DSC-TGA, TEM, SEM and XRD were characterized.
　　2 AC impedance, electrochemical hydrogen concentration cell and hydrogen molecules through (hydrogen pump) system and other methods studied BaCe1-xCaxO_3-α in the sample temperature (300 ~ 600 ° C) conductivity. Study: the sample temperature in the hydrogen atmosphere is pure proton conductor, x = 0.10 sample has the highest proton conductivity.
　　3 The study found that the conductivity of the sample synthesis method has a more significant impact on performance. Microemulsion synthesis of samples than the sol - gel synthesis of samples with higher conductivity. For example: For BaCe0.90Ca0.10O_3-α, microemulsion and sol - gel synthesized samples at 600 ° C respectively, the proton conductivity of 7.64 × 10-4 S · cm-1 and 1.22 × 10-4 S · cm-1.
　　4 successfully BaCe1-xCaxO_3-α proton conductivity in a series of samples the highest BaCe0.90Ca0.10O_3-α used in atmospheric ammonia. When applied at 480 ° C under the conditions of DC to 0.80 mA, the maximum yield of ammonia 2.69 × 10-9 mol? S-1? Cm-2, higher than the journal Science reported that ammonia production rate (electrolyte: SrCe0.95Yb0 .05 O_3-α, ammonia production rate: 7.5 × 10-11 mol? s-1? cm-2).
　　5 was synthesized using microemulsion BaCe1-xYbxO_3-α (x = 0.05, 0.10, 0.15, 0.20) Ceramic powder samples, at lower sintering temperatures http://www.chinamagnets.biz/ obtained dense ceramic samples. Samples in the series, x = 0.10 sample has the highest proton conductivity, 600 ° C when 1.17 × 10-2 S · cm-1. Will BaCe0.90Yb0.10O_3-α used in atmospheric ammonia in the 480 ° C, 0.60 mA of current conditions, plus the maximum yield of ammonia 1.98 × 10-9mol? S-1? Cm-2.
　　6 This is the first proton conductor of the Yb3-doped BaCeO_3 formaldehyde used in catalytic hydrogenation to methanol, the applied current of 10mA, 260 ° C the maximum yield of methanol 1.60 × 10-8mol · s-1 · cm-2 for the catalytic hydrogenation of organic matter provides an important basis.