The optical properties of thallium-like impurities in alkali-halide crystals

Ranfagni, A.; Mugnai, D.; Bacci, Mauro; Viliani, G.; Fontana, M. P.

doi:10.1080/00018738300101621

Cited by 334 publications

(200 citation statements)

References 164 publications

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“…Based on the existing literature, it can be ruled out that the sensitisation will work in oxides (including aluminates, sulphates, borates, phosphates), chlorides, bromides, sulphides or other more covalent (compared to F -) host lattices [121,122,123,126].…”

Section: +mentioning

confidence: 99%

Multi-Photon Phosphor Feasibility Research

Graham¹,

Chow²

2003

199

341

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Section: +mentioning

confidence: 99%

Multi-Photon Phosphor Feasibility Research

Graham¹,

Chow²

2003

199

341

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“…45 Good examples of the multivalent ions that can act as luminescent centers are rare-earth ions (e.g., Ce 3+ , Eu 2+ ), [6][7][8][9][10][11] transition metal ions (e.g., Cr 3+ , Mn 4+ ), [12][13][14][15][16][17] and ns 2 ions (ions with outer electron configuration of ns 2 , such as Tl + , Sn 2+ ). [18][19][20] Energy efficiency is critically important for phosphors used for lighting. To suppress the energy loss through nonradiative recombination, a phosphor is excited by directly exciting activators, not the host (see Fig.…”

mentioning

confidence: 99%

Using DFT Methods to Study Activators in Optical Materials

2015

ECS J. Solid State Sci. Technol.

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Density functional theory (DFT) calculations of various activators (ranging from transition metal ions, rare-earth ions, ns 2 ions, to self-trapped and dopant-bound excitons) in phosphors and scintillators are reviewed. As a single-particle ground-state theory, DFT calculations cannot reproduce the experimentally observed optical spectra, which involve transitions between multi-electronic states. However, DFT calculations can generally provide sufficiently accurate structural relaxation and distinguish different hybridization strengths between an activator and its ligands in different host compounds. This is important because the activator-ligand interaction often governs the trends in luminescence properties in phosphors and scintillators, which can be used to search for new materials. DFT calculations of the electronic structure of the host compound and the positions of the activator levels relative to the host band edges in scintillators are also important for finding optimal host-activator combinations for high light yields and fast scintillation response. Mn 4+ Luminescence of materials when excited by photons or ionizing radiation is the foundation for numerous technologies, such as energy efficient lighting (fluorescent lamps and white LEDs), laser, medical imaging, and nuclear materials detection.1-3 Efficient luminescence in semiconductors and insulators usually relies on the localization of excited electrons and holes at certain impurities, which act as luminescence centers (or activators). An activator can trap electrons and holes for efficient radiative recombination and is the essential component of a phosphor or scintillator material. The commonly used activators are typically multivalent ions, which can insert multiple electronic states inside the bandgap of the host material. 45 Good examples of the multivalent ions that can act as luminescent centers are rare-earth ions (e.g., Ce 3+ , Eu 2+ ), 6-11 transition metal ions (e.g., Cr 3+ , Mn 4+ ), [12][13][14][15][16][17] and ns 2 ions (ions with outer electron configuration of ns 2 , such as Tl + , Sn 2+ ). 18-20Energy efficiency is critically important for phosphors used for lighting. To suppress the energy loss through nonradiative recombination, a phosphor is excited by directly exciting activators, not the host (see Fig. 1a). The excitation energy is less than the bandgap energy of the host but is large enough to excite the activator. Since the excitation occurs locally at the activator, the chance for the excited activator to interact with nonradiative recombination centers, such as deep defects, is small. This is important for achieving high quantum efficiencies for phosphors. In scintillators used for detecting ionizing radiation, the radiation creates charge carriers in the valence and conduction bands of the host, which are subsequently trapped by activators, leading to radiative recombination (see Fig. 1b). In scintillators, a portion of the charge carriers need to travel a certain distance before being trapped by the activators, which ...

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“…Figure 7 shows a photograph of the xMnO2.5SnO57.5ZnO40P 2 O 5 glass under UV light irradiation (4.88 eV), and the chromaticity coordinates. It is notable that these glasses shows a high normalized QE value, comparable to that of practical MgWO 4 . This value enables us to confirm the potential application of the obtained RE-free glass as a phosphor with a high QE.…”

Section: Comparison Of Snmentioning

confidence: 74%

Preparation of rare-earth-free oxide glass phosphors

Masai

2013

J. Ceram. Soc. Japan

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Light emission in rare earth (RE)-free SnOZnOP 2 O 5 glasses is demonstrated. The RE-free transparent phosphate glasses show light emission with high quantum efficiency (QE) values, comparable to conventional crystalline phosphors, by excitation with deep-UV light. The broad emissions of the RE-free transparent glasses can be continuously tuned by both the amount of activator and the composition of the glasses, without reduction of the QE values. For future emitting devices, we believe that the lowmelting glasses will constitute one of the most industrially favorable inorganic materials possessing transparency and emitting properties.

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The optical properties of thallium-like impurities in alkali-halide crystals

Cited by 334 publications

References 164 publications

Multi-Photon Phosphor Feasibility Research

Multi-Photon Phosphor Feasibility Research

Using DFT Methods to Study Activators in Optical Materials

Preparation of rare-earth-free oxide glass phosphors

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