Luminescence characteristics of Y₂SiO₅:Tb phosphor particles directly prepared by the spray pyrolysis method

Tb-doped Y₂SiO₅ phosphor particles were prepared directly by a continuous droplet-to-particle preparation process using an ultrasonic spray generator. The photoluminescence characteristics of as-prepared and calcined particles were investigated. The particles of Y₂SiO₅ prepared below 1100 °C had poor crystallinity because of the short residence time of the particles inside the hot wall reactor, while the particles of Y₂SiO₅ prepared at 1200 °C had sharp crystallinity. The crystal structure of Y₂SiO₅ particles was changed from the X1 to X2 type after calcining above 1400 °C. Both prepared and calcined particles had spherical morphology, submicron size, and narrow size distribution. Agglomeration of particles did not occur even after calcining at 1200 °C. The prepared Y₂SiO₅:Tb particles absorbed excitation energy in the range from 220 to 325 nm, and the maximum excitation wavelength was near 240 nm. The main emission peak was 538 nm. The optimum brightness was obtained at the doping concentration of 4 atom %. The activation of terbium occurred directly even at short reaction times inside the hot wall reactor. The brightness of as-prepared particles increased with increasing temperature because of good activation and crystallization in high temperatures. The PL intensity of as-prepared particles at 1200 °C was 96% in comparison with maximum intensity of calcined particles.