The temperature-dependent characteristics of fluorescence of several rare-earth-doped ceramic phosphors has made these materials the focus of a major effort in the field of noncontact thermometry over the past few decades. These “thermographic phosphors,” e.g., Y2O3:Eu, have been used for remote measurements of the temperatures of both static and moving surfaces, and have performed many other tasks that standard sensors (thermocouples, thermistors, etc.) cannot. The range of usefulness of this class of materials extends from cryogenic temperatures to those approaching 2000 °C. The instrumentation needed for this type of thermometry has followed many different lines of development, and this evolution has produced a wide variety of both field- and laboratory-grade systems that are now described in the literature. In general, the technique offers high sensitivity (≈0.05 °C), robustness (e.g., stability of the sensor sample in harsh environments), and NIST traceability. In addition, such systems have been suc...

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Remote thermometry with thermographic phosphors: Instrumentation and applications

Cathode ray tube phosphors.

We have synthesized nanoparticles of ZnS doped with Mn for potential use as cathodoluminescent phosphors in field-emission displays (FEDs). We show that the cathodoluminescent efficiency of particles ⩽100 nm in diameter is within 40% of that of a commercial (micron-sized) phosphor when the electron-beam energy ranges between 500 and 3500 eV. The nanoparticles exhibit less current saturation than larger-sized phosphors, an important feature for use in FEDs. Furthermore, the nanoparticles were annealed at just 535 °C, hundreds of degrees below the processing temperatures of standard phosphors. Finally, we discuss the effect of the particle surface on low-voltage luminous efficiency.

Mn-doped ZnS nanoparticles as efficient low-voltage cathodoluminescent phosphors

Luminescent films of ZnS [Mn], Zn2SiO4 [Mn], Zn2(PO4)3 [Mn], and [Mn], CaF2 CaWO4[W] have been formed by evaporation in a vacuum and a subsequent heat treatment. Most of the films may be made either transparent or fogged depending on the post-heat treatment. The luminescent brightness of the fogged films, under cathode ray excitation, approaches the brightness of the bulk powdered material. The brightness of the transparent films is limited chiefly by internal reflection. In general, the phosphor chemistry of the powdered materials has been found to be applicable to thin films.

P. H. Dowling

Papers

Saturation and Voltage Effects in Cathodoluminescence