“…The impedance spectra were transformed into Nyquist plots. The plots were used to fit the parameters of an equivalent circuit consisting of ( R b Q b )( R gb Q gb )( Q el ), where R is the resistance, Q is the constant phase element, and the subscripts el, b, and gb refer to the electrode, bulk, and grain boundary, as described elsewhere. , The ionic conductivity was calculated as σ = L / RA , where L and A are the thickness and area of the pellet, respectively. In addition, possible hygroscopicity issues were also minimized by predrying the prepared pellets before cell assembly in an inert atmosphere.…”