The research of crystal structure and electrical properties of a new electrolyte material: Scandia and Holmia stabilized Zirconia

Abstract

Weakly agglomerated nano-crystalline Ho 2 O 3 and Sc 2 O 3 stabilized ZrO 2 (HoScSZ) powders are prepared by the hydrothermal method. Dense HoScSZ ceramic pellets are fabricated by isostatically pressing the powders then sintering at 1350°C for 2 h. All the HoScSZ samples are cubic phase verified by X-ray diffraction. 7 mol % Sc 2 O 3 + 1 mol % Ho 2 O 3 stabilized zirconia (7Sc1HoSZ) is verified by impedance spectroscopy possessing the higher conductivity than that of 8 mol % Sc 2 O 3 stabilized zirconia (8ScSZ). Space charge potential and specific grain boundary conductivity are calculated and fitted under the circumstance that the grain boundary is free of any amorphous phase which is verified by high resolution transmission electron microscopy. With the increase of the doping content of Ho 2 O 3 , the specific grain boundary conductivity and space charge potential decrease, while oxygen vacancy concentration increases.

Ionic Conductivity of Zirconia-Scandia-Dysprosia Solid Electrolyte

“…The behavior of the total conductivity may be represented by a single straight line. The activation energy for conduction (1.31 eV) obtained from the slope of the straight line is similar to those of other zirconia-scandia systems containing rare earths (6)(7)(8).…”

“…One approach to overcome the cubic phase decomposition is by introducing a second additive. In this context, it has been shown that rare earth oxides such as ceria, gadolinia, holmia, samaria, ytterbia and yttria are good candidates for phase stabilization in the zirconia-scandia system (3)(4)(5)(6)(7)(8). However, these additives influence the ionic conductivity.…”

Investigação da estabilidade de fases da zircônia-escândia

“…Com a finalidade de estabilizar a estrutura cúbica na zircônia-escândia e suprimir a transição de fase cúbica-romboédrica, característica do sistema binário para composições molares de Sc 2 O 3 entre 9,5 e 13%, 5,13 48 A principal propriedade avaliada, além da estrutura cristalina, é a condutividade iônica.…”

“…Os valores de energia de ativação para os materiais com e sem aditivos são da ordem de 1,40 eV (até 550 °C) e 0,80 eV (entre 550 e 800 °C), e estão de acordo com aqueles já reportados. 39,45,48…”