Surface reactivity and cation non-stoichiometry in BaZr_1−xY_xO_3−δ (x = 0–0.2) exposed to CO₂ at elevated temperature

Abstract

Surface formation of BaCO3 mainly proceeds by transfer of Y to the Ba-site while a BaZrO3 formula unit is consumed.

Effect of A-Site Nonstoichiometry on Defect Chemistry and Electrical Conductivity of Undoped and Y-Doped SrZrO3

“…The effect of the dopant partitioning was reported in a number of researches [15,22,27,28,29]. The ionic size of the dopant was shown to have an impact on its localization in perovskite lattice.…”

“…Since SrO and BaO exhibit high vapor pressure, their evaporation from cerates and zirconates of the alkaline earth elements can occur. To prevent the evaporation, special efforts, such as sintering in a sacrificial powder bed or using of Ba-saturated furnace furniture, should be made [20,21,22]. Therefore, we assume that strontium evaporation occurs in strontium zirconate during the high-temperature sintering and thermal etching.…”

“…First-principles calculations performed for Y-doped barium zirconate [22] also showed that there were Y ions residing on the Zr and Ba sites. Besides, it was concluded that local enrichment of Y in bulk and on the surface observed by X-ray photoelectron spectroscopy attained a structure similar to Y 2 O 3 that can be considered as precipitation of the yttrium-containing phase.…”

First principles calculations of the thermodynamic stability of Ba, Zr, and O vacancies in BaZrO3

“…22 Cation vacancy defects inuence the site occupancy of foreign atoms and dopants. 23,24 In this context, it is very important to determine the properties of the Ba vacancy at high temperatures. Also the Zr vacancies are responsible for the electrochemical properties and the thermodynamic stability of BZO.…”

Investigation of the electrostatic potential of a grain boundary in Y-substituted BaZrO3 using inline electron holography

“…However, since electron holography measures Δ tot ≈ Δ MIP + Δ E , and in this case |Δ MIP | ≫ |Δ E |, information about Δ E will be almost completely hidden. Barium deficiency starting in the GBs tends to occur during sintering of BZY samples [25,26], and should be expected in this sample as well, especially when considering the very high sintering temperature (2200 °C). Hence, the large Ba deficiency we observe at the GB core seems reasonable.…”