Pure HfO 2 and Gd-doped HfO 2 thin films have been grown on different single crystal substrates ͑silicon, R-Al 2 O 3 , and LaAlO 3 ͒ by pulsed laser deposition. X-ray diffraction ͑XRD͒ patterns show that the pure HfO 2 thin films are of single monoclinic phase. Gd-doped HfO 2 films have the same XRD pattern except that their diffraction peaks have a shift toward lower angles, which indicates that Gd dissolves in HfO 2. Transmission electron microscopy images show a columnar growth of the films. Very weak ferromagnetism is observed in pure and Gd-doped HfO 2 films on different substrates at 300 and 5 K, which is attributed to either impure target materials or signals from the substrates. The magnetic properties do not change significantly with postdeposition annealing of the HfO 2 films. In addition to the films, HfO 2 powders were annealed in pure hydrogen flow, and a ferromagnetic signal was not observed.
There is worldwide interest in the use of fluor materials that emit visible light when exposed to ionizing radiation. Typically, fluors are used as components in high performance electromagnetic calorimeters, down-hole oil well loggers, temperature sensors for equipment with high speed moving parts, and beam positioning systems for large particle accelerators. A candidate fluor should have a large fluorescence efficiency, small reduction in output as a function of exposure, intense visible fluorescence spectrum, large material density, and small prompt fluorescence decay time.Over the last few years, new fluor materials have been located by organizations such as Oak Ridge National Laboratory, Lawrence Berkeley National Laboratory, and the Department of Defense. These new fluors, such as YAIO3:Ce, YSiO5:Ce, GdSiO5:Ce, Y2O2S doped with Tb, Pr, and Eu, and Gd2O0S doped with Th, Pr, and Eu, show a great deal of promise for use in the applications listed above.This paper will present a summary of fluor research completed by the authors over the last ten years. These results will be used to establish a fluor characterization program at the Acadiana Research Laboratory (ARL) that will move it to the front of this developing technology.
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