SrHfO3-based phosphors and scintillators

Abstract

a b s t r a c tThe heavily Ce-doped SrHfO 3 (SHO) and the undoped non-stoichiometric SHO sample sets were prepared by solid state reaction in powder form and their luminescence spectra and decay kinetics were measured. Concentration quenching effects and thermally induced ionization of the Ce 3+ excited states were followed and discussed in the former sample set. In the latter one new emission band at about 334 nm was found in Sr-deficient samples and temperature dependences of its emission intensity and decay times were studied in the detail. Room temperature decay time of about 180 ns and efficient and fast energy transfer from the host to the center of the 334 nm emission make this material promising candidate for X-ray phosphors.

Luminescence and scintillation properties of Ce dope SrHfO3 based eutectics

“…slower decay component of 263 ns (55%). Observed decay time is comparable value with previous reports[11][12][13].…”

“…5 shows radioluminescence spectra of the Ce doped SHO/ SAO eutectic sample. The peaks in the wavelengths of 410 nm are attributed to Ce 3+ 5d-4f transitions in SHO according to the previous reports [11][12][13]. Ce 3+ 5d-4f emission of Ce doped SAO at 310 nm reported by other groups [16,17] was not detected.…”

“…Due to the high melting-temperature, it is difficult to grow the crystal from the melt in a crucible using conventional crystal growth methods such as Czochralski, Bridgman, and micro-pulling down (l-PD) method. Therefore, Ce:SHO scintillators were investigated in the form of nano-crystals and ceramics obtained from crystalline powders prepared by solid-state synthesis (Ji et al, 2005;Nikl et al, 2011; therefore, Ce:SHO scintillators were investigated in the form of nano-crystals and ceramics obtained from crystalline powders prepared by solid-state synthesis [10,11]. Scintillation properties of the Ce:SHO ceramics have been investigated by some groups [11][12][13] Maximum emission wavelength, light output and decay time under X-ray excitation of Ce:SHO prepared by a vacuum hot pressing or a hot isostatic pressing were determined to be 410 nm), 40,000 photons/MeV and 42 ns, respectively.…”

“…Scintillation properties of the Ce:SHO ceramics have been investigated by some groups [11][12][13] Maximum emission wavelength, light output and decay time under X-ray excitation of Ce:SHO prepared by a vacuum hot pressing or a hot isostatic pressing were determined to be 410 nm), 40,000 photons/MeV and 42 ns, respectively. In addition, timing resolution of ceramics Ce:SHO was 276 ps [11].…”

Delayed recombination and excited state ionization of the Ce3+ activator in the SrHfO3 host

“…There must be another mechanism at work responsible for the low temperature signal. One should point out that such a low temperature signal is not restricted to a certain class of materials or specific recombination center, since such remnants were already observed by us in several different types of oxides doped either by Ce 3+ (current work, [8]) or Pr 3+ [4,9] or even in the undoped ones [10]. It has been obtained even for Y 3 Al 5 O 12 :Pr and Lu 3 Al 5 O 12 :Pr where thermally induced ionization was not detected below 500 K. Since this is evidently a kind of sub-gap process which does not involve the conduction band of the host, one candidate to explain such a phenomenon could be quantum tunneling between the recombination center and a nearby trap.…”