DEVELOPING FIRST-PRINCIPLES REACTIVE FORCE FIELDS AND DENSIFICATION PROCESS FOR Y-DOPED BaZrO3 PROTON-CONDUCTING CERAMICS

摘要

During the third semi-annual period we have mostly finished a series of QM calculations on relevant metals (Pt, Zr, Y, Ba), metal alloys (Y/Zr), metal oxides (ZrO{sub 2}, Y{sub 2}O{sub 3}, BaO) and Y-doped BaZrO{sub 3}. Based on these data we started developing ReaxFF for further MD simulations of different physico-chemical processes in the electrolyte and at the electrode/electrolyte interface. To accelerate the densification process of BaZrO{sub 3} ceramics at lower temperature an initial screening of all transition elements in the series Sc to Zn has been carried out. It turned out that NiO, CuO and ZnO are the most effective additives for enhancing barium zirconate densification. Characterization (X-ray diffraction, scanning electron microscopy, and impedance spectroscopy) of Zn-, Cu- and Ni-modified BYZ has been performed. The temperature dependence of the bulk conductivity {sigma}{sub gi}, grain boundary conductivity {sigma}{sub gb}, and specific grain boundary conductivity {sigma}{sub sp.gb} were measured. The bulk conductivity of BYZ-Zn4 is slightly lower than that of unmodified BYZ.