SUMMARY

Although research and development and production of powder phosphor materials takes place at some of the sites visited, the main development and production facility appears to be at the Phosphor Institute and at an associated government stock company in Stavropol (Dr. Vladimir Vituk, Director). Unfortunately, this site was not included on the WTEC agenda since it is difficult to travel there, and at the time of the trip there was civil unrest at the Georgian border, where Stravropol is located. Therefore, this report concerning luminescent materials may be incomplete without input from this facility.

However, the strengths of the work in powder phosphors appear to be in the development of low-voltage materials and multicomponent phosphors that emit different colors depending on the beam voltage or current. The low voltage structure in VFDs provides very high brightness, high lifetime (approx. 100,000 hrs), and multicolor capability. There seems to be significant development of oxide (particularly Y-oxide) phosphors.

For electroluminescent displays, thin-film materials include ZnS, ZnSe, and ZnS:Mn, with colors of yellow orange, red, green, and blue. A new type of EL indicator based on the integration of a thin-film luminescent structure and active layers of ferroelectric ceramics has been developed recently. There has been considerable work in EL displays at brightness levels greater than 50,000 lx with yellow green color, with a lifetime greater than 10,000 hrs. Significant improvements in blue or white phosphors were not reported.

The progress in R&D for FED cathode emitters appears to be significant, particularly carbon fiber cathodes and the patterned growth of silicon needles. The deposition of diamond microspheres on the silicon needles could have significant applications in field emitter devices, especially if uniformity of deposition can be achieved and if the diamond spheres can be doped for negative electron affinity.

The materials developed for LEDS are SiC and III-V semiconductors. Amorphous SiC structures deposited onto flexible substrates have been developed recently. The work on the growth of single crystal II-VI lasing materials is impressive, particularly with applications for projection TV. The development of organic photochromic/ electrochromic materials appears to be advanced.


Published: December 1994; WTEC Hyper-Librarian