科研之友
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摘要
One-micron-sized uniform red-phosphor spheres of an (Y,Gd)BO3 ternary system have been converted from their colloidal moydite precursor spheres facilely synthesized using modified homogenous precipitation. The moydite spheres, possessing the composition (Y0.95-xGdxEu0.05)(B(OH)(4))CO3 (0 <= x <= 0.50), are orthorhombic in structure. Gd3+ is more effective than Y3+ in raising nucleation density, leading to a decreased average size of the precursor particles with a higher addition of Gd3+. The lattice parameters, a and b, increase linearly with increasing Gd incorporation, while the c value shrinks with a higher Gd content. The moydite spheres completely decomposed into hexagonal orthoborate upon heating to 800 degrees C, while retaining the spherical shape and excellent dispersion of the original particles. However, they lost their spherical shape and underwent significant aggregation at a higher temperature. The lattice constant of (Y0.95-xGdxEu0.05)BO3 calcined at 800 degrees C follows Vegard's law and increases linearly with an increase in the value of x from 0 to 0.30. Upon excitation with 207 nm wavelength light, (Y0.95-xGdxEu0.05)BO3 spheres show typical Eu3+ emission, with the strongest emission at 610 and 627 nm (D-5(0)-> F-7(2) transition of Eu3+) and almost the same CIE chromaticity coordinates of (similar to 0.632, similar to 0.373). The incorporation of Gd3+ resulted in enhanced luminescence intensity and shorter lifetimes (similar to 5.77-6.56 ms). The optimized doping concentration of Gd3+ is 15 at%. The uniform phosphor spheres obtained in this work are expected to have wide applications for the contemporary interest in high-resolution display technologies.
