Low voltage operated display devices require thin fluorescent screens of 3 to 4 micrometer, consist of 0.1 to 2.0 micrometer size phosphor particles. Fine grain phosphors are synthesized by hydrothermal, combustion and sol-gel processes. In sol-gel process, the pores in dried gels are often extremely small and the components of homogeneous gels are intimately mixed. The surface area of powders produced from sol-gel is very high, leading to a lower processing temperature. Stable sols of Y(OH)₃, Al(OH)₃ and RE(OH)₃ were prepared by passing respective nitrates through an ion exchange column. Stiochematric amounts of these sols were mixed to obtain YAG:RE (0.001 to 5.0 m/o) phosphors. DTA/TGA analysis showed weight loss corresponding to the loss of water molecules and oxidation. XRD of the samples fired at 1200 degrees Celsius showed only YAG phase. SEM studies revealed that the phosphor particles are nearly spherical in shape and uniform in size. Emission spectra from these samples excited by 200 to 5000 eV, exhibited a number of lines in blue, green and red regions corresponding to Tm³⁺, Tb³⁺ and Eu³⁺ transitions. Introduction of inhibitors (Li⁺) and sensitizes (Pr³⁺) appears promising in improving the morphology as well as the efficiency of the phosphors.

Date Published: 11 March 1996
PDF: 8 pages
Proc. SPIE 2651, Liquid Crystal Materials, Devices, and Applications IV, (11 March 1996); doi: 10.1117/12.235348

Published in SPIE Proceedings Vol. 2651:
Liquid Crystal Materials, Devices, and Applications IV
Ranganathan Shashidhar, Editor(s)