Glass-ceramics of the boron-, aluminium- or gallium-containing Na5RSi4O12-type (R = rare earth; Y) Na (+)-superionic conductors were prepared by crystallization of glasses with the composition Na-3 + 3x + yY1-xXySi3-yO9 (X = B; NaYBSi, X = Al; NaYAlSi, X = Ga; NaYGaSi) (x = 0.2, y = 0.1). The crystallization kinetics of the glasses was examined by DTA, and the effects of X elements on the separation of the phase and the microstructural effects on the conduction properties of glass-ceramics were discussed. The activation energies of crystal growth of the NaYBSi, NaYAlSi and NaYGaSi glasses with the Na3.7Y0.8B0.1S2.9O9, Na3.7Y0.8Al0.1Si2.9O9 and Na3.7Y0.8 Ga0.1Si2.9O9 compositions were 410,392 and 382 kymol, respectively. The conductivities of the glass-ceramic NaYBSi, NaYAlSi and NaYGaSi were 432 x 10(-2). 3.73 x 10(-2) and 3.40 x 10(-2) S/cm at 300 degrees C, respectively. (C) 2012 Elsevier B.V. All rights reserved.