Alkaline earth-doped La2Zr2O7 oxides with a pyrochlore structure: phase equilibria and electrical properties

A row of La2-xSrxZr2O7-delta (X = 0.00, 0.05, 0.10, 0.15, 0.50) oxides was synthesized using the citrate-nitrate method. The solubility limit for strontium in La2Zr2O7 was found to be 0.07 according to the XRD analysis. At a higher strontium content, the second phase of SrZrO3 was observed. Electrical conductivity of La0.95M0.05Zr2O7-delta (M = Ca, Sr) oxides has been studied by means of impedance spectroscopy in wet and dry air in the temperature range of 300-550 degrees C. Total electrolyte resistance was divided into bulk and grain boundary contributions. The total, bulk, and grain boundary conductivity values in wet air were found to be higher than the corresponding values in dry air. The response of the Sr-doped oxide on humidifying the atmosphere was found to be more pronounced than that of the Ca-doped one. The influence of acceptor doping on electrolyte conductivity is discussed.

Automated summary

La2-xSrxZr2O7-delta oxides were synthesized using the citrate-nitrate method, with the solubility limit for strontium in La2Zr2O7 found to be 0.07. A second phase of SrZrO3 was observed at higher strontium content. The conductivity of the electrolyte in wet air was higher than in dry air, with Sr-doped oxides showing a more pronounced response.