Electrical properties of proton-conducting BaCe0.8Y0.2O3-δ and the effects of bromine addition

Abstract

A detailed analysis of the electrical properties of the proton-conducting BaCe0.8Y0.2O3- phase (BCY20) and the effects of Br doping has been undertaken. Members of the system of nominal stoichiometry BaCe0.8Y0.2O2.9-(x/2)±Brx (x = 0, 0.05, 0.1 and 0.2) were synthesised by a citrate-nitrate process and high-temperature annealing up to 1500 °C. Xray diffraction revealed the formation of single-phase material with a monoclinically distorted perovskite structure (space group I2/m) with greater distortion for Brsynthesised phase. Significant contrasts in electrical behaviour and stability between BCY20 and Br-synthesised series members were also found. However, chemical analysis by total X-ray fluorescence spectroscopy indicated that only trace amounts of Br remain after synthesis, indicating that Br addition influences stoichiometry but not directly the physicochemical properties. Higher conductivity is observed for the Br-synthesised compositions in wet and dry oxidising conditions in the temperature range 300-900°C, reaching a value of 5.8 S•m -1 at 800 ºC for the x = 0.2 member in wet O2 (pH2O ~ 0.022 atm). Determination of partial-conductivity components indicated that, in humid conditions and low temperature, conductivity of 20% Br-synthesised material is principally protonic (tH = 0.91 at 600 °C and pO2 = 0.2 atm) and superior to that of BCY20. Mixed oxide-ionic-electronic conductivity dominates at high pO2 (1 atm) and oxide-ionic conductivity at low pO2 (~ 10 -4 atm) in the temperature range 600-900 ºC for both BCY and Br-doped samples. Stability was found to be poorer in CO2 for the Brsynthesised phases as determined by thermogravimetry and prolonged conductivity measurements.

Fluoride‐Based Anion Doping: A New Strategy for Improving the Performance of Protonic Ceramic Conductors of the Form BaZrO3

“…demonstrated a stable electrolyte by doping F − in barium cerate oxides . Higher conductivity was observed for the Br − doped BaCe 0.8 Y 0.2 O 3‐δ but with poor stability than the parent perovskite …”

Advances in developing protonic ceramic cells

“…[5,40] ( 에 가깝게 만들어 안정성을 개선할 수 있다. [30,45] B-site 도펀트 이온 치환은 주로 결함의 형성에 관여 하고 추가적으로 lattice volume 변화에 영향을 끼친다. S/cm at 600℃).…”

“…earth, B= Nb, Ta) 구조가 있다. [26][27][28][29][30] 하지만, 페로브 이다. [31,32] Analysis (TGA) 분석을 이용해 계산할 수 있다.…”

Fluorine-containing oxygen electrodes of the nickelate family for proton-conducting electrochemical cells

“…Regarding the functional materials that can be used in PCECs or PCFCs, the anionic modification of brownmillerite-type Ba 2 In 2 O 5 -based protonic conductors using halogens has been intensively studied over the last decade by Animitsa et al [36][37][38][39][40]. Later, F-, Cl-and Br-doping was used for classical BaCeO 3 -based electrolytes having a perovskite structure [41][42][43][44][45]. However, studies of anionic modification of oxygen-conducting electrode materials for protonic ceramic electrochemical cells are limited to only a few works [45,46] and need to be extended to gain a better understanding of the corresponding effects on electrode performance.…”