Fabrication and electrical characterization of 15% yttrium-doped barium zirconate—nitrate freeze drying method combined with vacuum heating

The best composition of an Y-doped BaZrO3 electrolyte: selection criteria from transport properties, microstructure, and phase behavior

“…3(e)), the amount of the fine grains reduced obviously with the increasing heating time. After heating at 1600 o C for longer than 40 h, quite uniform grain size was observed, in agreement with the previous report in our group [34]. Extending the heating time to 200 h results in the grain size increasing to around 2 μm ( Fig.…”

High Performance Protonic Ceramic Fuel Cells with Acid-Etched Surfaces

“…There is third benefit; that is, barium zirconate has a refractory nature and for sintering a quite high temperature, typically at around 1600 C or higher, is needed; however, vapor loss of BaO or Ba(OH) 2 is not negligible at such a temperature, which causes a marked drop in proton conductivity. 7,23,24 Mechanical polishing is therefore usually employed to remove the less conductive layer on the surface. Etching can remove this layer.…”

To Journal of Phase Equilibria and Diffusion Phase Relationship of the BaO-ZrO2-YO1.5 System at 1500 and 1600 °C

“…Yttrium-doped barium zirconate is known to have the lowest protonic resistance of grain interior among trivalent cation-doped barium zirconate and this property attracts many researchers. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] In the previous works, we investigated a sintering mechanism of 15% yttrium-doped barium zirconate (BaZr 0.85 Y 0.15 O 3-d ) at 1600°C based on the idea of twophase separation of yttrium poor barium zirconate and yttrium rich barium zirconate phase in the sample by conventional solid state reaction. [19,20] A phase separation at 1600°C was reported by Kojima et al [23] However, the points we discussed are that there is no phase separation in equilibrium at 1600°C, but traces of the phase separation at synthesizing temperature, 1300°C, might remain even at 1600°C.…”

“…Based on the proposed mechanism, we succeed in sintering wellgrain-grown 15% yttrium-doped barium zirconate with a powder obtained by a nitrate freeze-drying method and synthesis at 500°C which is finer and more homogeneous than that by solid state reaction route. [22] In this study, we try to provide the evidence of the phase separation by investigating phase relationships of a BaOZrO 2 -YO 1.5 system at synthesizing temperature, 1300°C, and sintering temperature, 1600°C. However, it was very difficult to obtain phase equilibration at the synthesizing temperature, at 1300°C, due to a kinetic reason, [20] this study has investigated the phase relationship of the BaO-ZrO 2 -YO 1.5 system at 1500°C, instead of 1300 and 1600°C.…”