Investigation of electrical and mechanical properties of 3Y-TZP/Cubic zirconia solid electrolytes with composite structure prepared by near net shape forming

Yttria doped zirconia solid electrolytes with non-equilibrium composite structure were prepared by impregnation of a porous 3Y-TZP matrix with a solution of yttrium nitrate. Microstructures were characterized by XRD and SEM. The electrical properties were studied by impedance spectroscopy as a function of temperature. Biaxial flexural strength and fracture toughness of composite samples were measured by ring on ring and Vickers microhardness indentation methods respectively. The yttria content of the electrolytes was increased by a multi impregnation process. It was concluded that electrical and mechanical properties of the electrolytes can be adjusted by controlling the amount of doped yttria especially if severe sintering treatments are avoided. Electrolytes with conductivity of 0.08 S/cm at 900 degrees C and fracture strength and fracture toughness of respectively 390 MPa and 2.9 Mpa m(1/2) were obtained. (c) 2009 Elsevier B.V. All rights reserved.</p

Investigation of electrical and mechanical properties of 3YSZ/8YSZ composite electrolytes

The effects of addition of 3YSZ (3 mol% yttria stabilized zirconia) on electrical and mechanical properties of 8YSZ (8 mol% yttria stabilized zirconia) has been investigated. Three different composites of 3YSZ/8YSZ with compositions of 10 wt.%, 25 wt.% and 35 wt.% of 3YSZ were prepared by conventional solid oxide mixing followed by sintering. Microstructures were characterized by XRD and SEM. The electrical properties were studied by impedance spectroscopy as a function of temperature. Biaxial flexural strength and fracture toughness of composite samples were measured by ring on ring and Vickers microhardness indentation methods respectively. Results of electrical conductivity measurement proved that by increasing the 3YSZ content of the composite samples, the electrical conductivity at high temperatures (T&gt;550 degrees C) decreased while at low temperatures (T&lt;550 degrees C) the conductivity increased. In addition, composite electrolytes had lower activation energy of conductivity at both low and high temperatures. It was shown that both toughness and fracture strength of composite samples improved by the addition of 3YSZ particles. (C) 2008 Elsevier B.V. All rights reserved.</p

Production of high conductivity composite zirconia solid oxide electrolytes with good mechanical strength through net-shape

Yttria- and scandia-doped zirconia composite solid electrolytes were prepared by impregnation of a porous tetragonal 3 mol% Y2O3 zirconia matrix with a solution of scandium nitrate in a net-shape type process. The resulting composite exhibited both high conductivity (0.01 S cm(-1) at 903 K) and good mechanical strength and fracture toughness. This excellent performance can be attributed to the achievement of a favourable inhomogeneous structure of the core-shell type. Grain surfaces are enriched with scandia dopant to improve both crystal and grain boundary conductivities with formation of cubic zirconia at these interfaces, whilst retaining the small grain size of the tetragonal phase, which optimises mechanical properties and favours production of thin electrolytes.</p