Optical studies of Pb<sup>2+</sup>ions in a LiBaF<sub>3</sub>crystal

Aminov, L. K.; Nikitin, S. I.; Silkin, N. I.; Shakhov, A A; Yusupov, R. V.; Abdulsabirov, R. Yu.; Кораблева, С. Л.

doi:10.1088/0953-8984/18/20/021

Cited by 15 publications

(5 citation statements)

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“…But a large energy separation between the lowest excited state 3 P 0 and the 3 P 1 states can also result from the strong spinorbit splitting and reduce the electron population on the radiative 3 P 1 state. 56 Many previous experiments on Pb and Bi activated phosphors and scintillators involve uoride or oxide-based largeband-gap host materials, 56,57,[59][60][61][62] which have narrow valence band width and low VBM. 63 This may lead to the electronic structure depicted in Fig.…”

Section: Discussionmentioning

confidence: 99%

Chemical trends of electronic and optical properties of ns² ions in halides

2014

J. Mater. Chem. C

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Section: Discussionmentioning

confidence: 99%

Chemical trends of electronic and optical properties of ns² ions in halides

2014

J. Mater. Chem. C

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“…But a large energy separation between the lowest excited state 3 P 0 and the 3 P 1 states can also result from the strong spin-orbit splitting and reduce the electron population on the radiative 3 P 1 state. 92 Many experiments on Pb and Bi activated phosphors and scintillators involve fluoride or oxide-based large-band-gap host materials, 92,93,[96][97][98][99] which have narrow valence band width and low VBM. 100 This may lead to the electronic structure depicted in Fig.…”

Section: Ns 2 Ions As Activatorsmentioning

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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“…In the 'inverse' perovskite with cubic structure, the monovalent ion Li þ is at the center of six F À octahedrons and the Ba 2þ divalent ions are in the 12-fold environment site, which is different from the classic perovskite structure [13].…”

Section: Calculation Modelmentioning

confidence: 96%