Translucent Gd2Si2O7:Ce (GPS:Ce) polycrystalline plates were prepared via liquid-phase sintering using SiO2 as a self-flux, and their scintillation performances for alpha-particles were investigated. Dense sintered compacts comprising large grains, some of which were larger than 100 mu m in diameter, were successfully prepared by sintering at 1690 degrees C for 100 h. The best result was obtained with the powder comprising only <40 mu m particles. Any combination of powders of <40 mu m and <15 mu m resulted in inhomogeneous structures with smaller grains of about 50 mu m. A translucent GPS:Ce thin plate was fabricated by grinding the sintered compact that contained excess SiO2 of 8 mol%. Since the plate was composed of large grains, scattering at the grain boundaries was effectively suppressed and many of the grains virtually act as single crystals when the plate thickness was less than 100 mu m. Therefore, the decrease in the plate thickness brought increase in the total transmission, and light yield and energy resolution were consequently improved. When the plate thickness was 50 mu m, light yield was 82% as compared with that of a GPS:Ce single crystal as a reference, and energy resolution attained to 13%. (C) 2015 Elsevier B.V. All rights reserved.