Improving the efficiency of a blue-emitting phosphor by an energy transfer from Gd to Ce

The low-voltage efficiency of the blue-emitting phosphor, cerium activated yttrium silicate (Y1 mCem)2SiO5, has been improved by co-activating with gadolinium, (Y1 m nCemGdn)2SiO5. Gd 3+ improves the efficiency by transferring energy to Ce, and makes this phosphor a more promising candidate for low-voltage field emission flat panel displays. Low-voltage cathodoluminescence and photoluminescence measurements were made to determine the optimum concentrations of Gd that yielded the most luminous efficient phosphor. For photoluminescence, Ce most efficiently luminesces at the excitation wavelength lex 1⁄4 358 nm. Co-activating with Gd 3+ did not improve the photoluminescent efficiency because Gd does not absorb at Ce excitation energy, and thus cannot transfer energy. For low-voltage cathodoluminescence, co-activating with Gd did improve the efficiency since Gd was sufficiently excited, with the optimum composition found to be (Y0.8425Ce0.0075Gd0.15)2SiO5. r 2002 Elsevier Science B.V. All rights reserved. PACS: 78.55. m; 78.60. b