Synthesis and Na+ conduction properties of Nasicon-type glass–ceramics in the system Na2O–Y2O3–R2O3–P2O5–SiO2 (R = rare earth) and effect of Y substitution

Glass–ceramics of the phosphorus-containing Na5RSi4O12-type (R = rare earth) Na+-superionic conductors were prepared by crystallization of glasses with the composition Na3 + 3x + yY1 − x − zRzPySi3 − yO9 (NaYRPSi; R = Nd, Sm, Eu, Gd, Dy, Er, Yb) (x = 0.4, y = 0.2, z = 0.1). The crystallization kinetics of the glasses was examined by DTA, and the effects of R elements on the separation of the phase and the microstructural effects on the conduction properties of glass–ceramics were discussed. The activation energy of crystal growth of the NaYRPSi glass decreases as the ionic radius of R is increased. The conductivity of the NaYRPSi glass–ceramics increases as the ionic radius of R is increased.