Solid State Ionics, Vol.167, No.3-4, 389-397, 2004
Proton solubility for La2Zr2O7 with a pyrochlore structure doped with a series of alkaline-earth ions
Alkaline-earth ion doped LaZr2O7 samples with a pyrochlore structure, i.e., (La2-xMx)Zr2O7-delta and La-2(Zr2-xMx)O7-delta (M=Mg, Ca, Sr and Ba), were prepared by conventional ceramic methods. The quantity of protons dissolved in the crystal was evaluated by evolved H2O gas, which was detected by a quadrupole mass spectrometer. The relationship between the proton solubility of the La2Zr2O7-based high temperature proton conductor and the basicity around the dopant, which is referred to as local basicity in the present paper, was studied. Proton solubility normalized by the positive charge introduced by doping was adopted to allow comparison of the proton solubility among the samples with different doping levels. Because the basicity of the alkaline-earth oxide is well-known to be ranked as MgO