Preparation, Electrical Conductivity, and Thermal Expansion Behavior of Dense Nd _{1− <i>x</i>} Ca <i> _x </i> CrO ₃ Solid Solutions

Abstract

Nd 1− x Ca x CrO 3 (0≤ x ≤0.25) solid solutions are synthesized using a two‐step calcination solid‐state reaction method and can potentially be used as interconnect applications in solid oxide fuel cells (SOFCs). The lattice parameters and unit cell volume decrease with an increase of the Ca 2+ dopant concentration at the A‐site. On the other hand, the relative density, electrical conductivity, and thermal expansion coefficient (TEC) increase with an increase of Ca 2+ contents. Calcium doping significantly depresses the chromium vaporization of NdCrO 3 , thus accelerating the sintering and densification of the oxides. Nd 1− x Ca x CrO 3 with x =0.25 shows the best electrical conductivity of 28.8 and 1.1 S/cm at 850°C in air and hydrogen, respectively, with a high relative density of 98.0% and a good TEC of 9.19 × 10 −6 K −1 in the temperature range from 30° to 1000°C in air. This indicates that Nd 0.75 Ca 0.25 CrO 3 is a promising candidate as an interconnect material for application in SOFCs.