Gd³⁺ and Bi³⁺ co-substituted cubic zirconia; (Zr_1−x−yGd_xBi_yO_2−δ): a novel high κ relaxor dielectric and superior oxide-ion conductor

Abstract

The high polarizability of the Bi3+ ion coupled with synergistic interaction of Bi and Gd in the host ZrO2 lattice seems to create the more labile oxide ion vacancies that enable high oxide ion conductivity at lower temperatures.

Highly efficient Bi-promoted ZrO2-based materials for non-oxidative propane dehydrogenation

“…In this regard, bismuth oxide may be an attractive promoter because it enhances the ionic conductivity of the accordingly promoted ZrO 2 -based solid electrolytes at intermediate (600–800 °C) temperatures. 12–14 Substitution of Zr 4+ sites by Bi 3+ leads to the creation of “structural” oxygen vacancies due to the charge compensation. Moreover, the high polarizability of Bi 3+ cations with 6s 2 lone pair electrons additionally increases the mobility of lattice oxygen in the lattice of ZrO 2 , which is important for the formation of “generated” Zr cus sites.…”

“…2(b)) implying that Bi 2 O 3 itself unlikely catalyses the dehydrogenation reaction. Accordingly, the enhanced rate of propene formation over pre-reduced Bi-containing materials compared to bare ZrO 2 or ZrO 2 modified by other promoters can be related to the superior oxide-ion conductivity of Bi-modified ZrO 2 , 14 which seems to be required to facilitate the formation of active Zr cus sites under reductive conditions through the removal of lattice oxygen.…”