Defect luminescence in CaF2 nanoparticles

Luminescence and stability of Tb doped CaF2 nanoparticles

“…33 For the samples irradiated at 486 nm, only the TL glow curve due to the deep traps was observed at about 640 K. The TL results support two ideas: (i) the observed long Tb 3+ lifetime can be ascribed to the presence of traps, and (ii) the reduction in the PL lifetime of Tb 3+ excited at longer wavelengths could also be associated with unsuccessful activation of traps, although cross-relaxation energy transfer cannot be ignored since it was evidenced by the intensity decreased of 5 D 3 emission as a function of Tb content. In previous studies of the cross-relaxation energy transfer of Tb 3+ ions, the lifetime of 5 D 3 energy level was drastically decreased whereas the lifetime of 5 D 4 was almost unaffected, 9,12 unlike in our case where both lifetimes were decreased. Surprising when the samples were irradiated with a longer wavelength of 482 nm (blue light), only the TL glow curve peaks associated with deep traps and not shallow traps were observed.…”

“…The uorine centre is found to be one of the most prominent defects and it form complexes when it is perturbed by the parasitic oxygen ions that are always present in CaF 2 crystals. [12][13][14][15] On the other hand, recent research is focused on doping CaF 2 with different rare earth ions in order to develop an excellent CaF 2based photonic material for various applications such as lasers, bioimaging, lighting, thermoluminescence, etc. Nevertheless, a systematic investigation addressing the role of these defects on the luminescence dynamics of rare earth ions incorporated in CaF 2 host has rarely been performed.…”

Er3+-doped transparent glass ceramics containing micron-sized SrF2 crystals for 2.7 μm emissions

“…However, network modifiers and impurities in the glass matrix tend to accumulate on the surface of the nanocrystals because of the high surface energy, which may change the properties of the nanocrystals 17 . Meanwhile, defect energy levels are easily introduced into the forbidden band of nanocrystals because of large surface defects, resulting in defect luminescence 18 . Large grains can prevent the problems encountered in nanocrystals because of a small surface-to-volume ratio.…”

Влияние Отжига На Структурные, Текстурные, Термические, Магнитные И Люминесцентные Свойства Наночастиц Фторида Кальция

“…3). Уменьшение интенсивности ФЛ указывает на небольшое уменьшение концентрации F-центров, по-видимому, из-за их частичной рекомбинации с возможными дырочными центрами типа Vk, сформировавшимися во время испарения мишени [88,89] Oднако дальнейшее повышение температуры отжига привело к значительной трансформации ФЛ спектров отожженных образцов (рис. 6, c, d На обоих ФЛ спектрах образцов S400 и S900 исчезла длинноволновая полоса при 702 nm, и появилась новая желтая полоса при 581 nm.…”