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SUMMARY:Exciton-like and defect-related luminescence in K3WO3F3  oxyfluori
 de crystals
DTSTART;VALUE=DATE-TIME:20160705T090000Z
DTEND;VALUE=DATE-TIME:20160705T100000Z
DTSTAMP;VALUE=DATE-TIME:20260814T150859Z
UID:indico-contribution-1242@indico.inp.nsk.su
DESCRIPTION:Speakers: Vladimir Pustovarov (Ural Federal University)\nCompl
 ex metal oxyfluorides such as K3WO3F3 are attractive compounds for develop
 ing new noncentrosymmetric crystals having ferroelectric and ferroelastic 
 properties. This is achieved due to the strong distortion of metal-(O\,F) 
 polyhedra in crystal lattice because of different ionicity of metal-O and 
 metal- F bonds. The luminescence spectroscopy can be a sensitive method to
  study the character of lattice distortion of these compounds.\nSpectra of
  photoluminescence (PL) and X-ray excited luminescence\, PL excitation spe
 ctra (3–22 eV)\, PL decay kinetics as well as thermoluminescence curves 
 were measured for single crystals and ceramics K3WO3F3. Synchrotron radiat
 ion (HASYLAB\, DESY\, Hamburg) were used for low temperature PL experiment
 s with time resolution. Crystals were grown and examined in Institute of G
 eology and Mineralogy SB RAS (Novosibirsk). \nThe intrinsic luminescence o
 f tungstates is usually ascribed to the radiative relaxation of exciton-li
 ke excitations localized on WO6 octahedra or WO4 tetrahedra. In K3WO3F3 th
 ere are anion sites with mixed oxygen/fluorine occupancy. Therefore\, diff
 erent octahedra form with different distortion. Two emission centers of ex
 citon-like origin\, with distinct relaxation time\, different types of suc
 h octahedra were found. The time-resolved luminescence spectroscopy techni
 que was applied to distinguish these centers\, proving itself as a sensiti
 ve method to study the character of lattice distortion. The energy transfe
 r mechanism between these PL centers is found and tentatively described by
  the diffusion of excitons. Apart from intrinsic luminescence\, the PL of 
 defect-related centers was found in samples irradiated by fast electrons f
 rom linear accelerator (E=10 MeV\, D=120 Gy). The role of shallow charge c
 arrier traps in the low-temperature luminescence was revealed.\n\nhttps://
 indico.inp.nsk.su/event/3/contributions/1242/
LOCATION:Budker INP 2nd and 3rd floors
URL:https://indico.inp.nsk.su/event/3/contributions/1242/
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