High-temperature crystal structure and transport properties of the layered cuprates Ln2CuO4, Ln=Pr, Nd and Sm

Abstract

High-temperature crystal structure of the layered cuprates Ln 2 CuO 4 , Ln=Pr, Nd and Sm with tetragonal T'-structure was refined using X-ray powder diffraction data. Substantial anisotropy of the thermal expansion behavior was observed in their crystal structures with thermal expansion coefficients (TEC) along a-and c-axes changing from TEC(a)/TEC(c)≈1.37 (Pr)

Influence of structural arrangement of R2O2 slabs of layered cuprates on high-temperature properties important for application in IT-SOFC

“…Anisotropy of the thermal expansion is observed for both compounds and the TEC(a)/TEC(c) [9]. Apparently, partial replacement of Sr for Pr leads to the appearance of rock-salt slabs in the crystal structure and creates longer interatomic distances between A-cation and O atoms making the thermal expansion behaviour of Pr 2-x Sr x CuO 4 similar to that found for other layered compounds.…”

“…However, layered cuprates with T'-structure have a number of advantages as cathode materials in IT-SOFC. This especially concerns Pr 2 CuO 4 having high total electrical conductivity >100 S/cm at 1173K and low linear TEC of 11.8 ppm K -1 [9].…”

Advances in Cathode Materials for Solid Oxide Fuel Cells: Complex Oxides without Alkaline Earth Metal Elements

“…The Pr 2 CuO 4 is another choice as it has a much high conductivity of around 100 S cm −1 at 700 °C. [ 341 ] The polarization resistance of a non-optimized Pr 2 CuO 4 electrode was about 1.7 Ω cm 2 at 700 °C, and this electrode showed a better short-term chemical compatibility with GDC electrolyte than La 2 CuO 4 and Nd 2 CuO 4 . [ 345 ] The charge transfer process was believed to be the rate determining step for ORR over the Pr 2 CuO 4 electrode.…”

“…However, the main drawback of Nd 2 CuO 4 and Sm 2 CuO 4 materials for application in SOFCs was their low electrical conductivities (less than 1 S cm −1 ) at working temperature. [ 341 ] To improve the electronic conductivity, Khandale et al As expected, an increased electrical conductivity could effectively enhance the electrical performance of a T'-structure phase. The Pr 2 CuO 4 is another choice as it has a much high conductivity of around 100 S cm −1 at 700 °C.…”

“…But, it should be noted that the La 2 CuO 4 oxide could still crystallize in the K 2 NiF 4 -type structure. [ 341 ] A Ce-doped Nd 2 CuO 4 with T'-structure was fi rst applied as an oxygen reduction electrode for SOFCs, but the electrode microstructure was poor and a relatively low electrode [ 331 ] Copyright 2013, Elsevier.…”