Vibronic Structure in Luminescence Spectra of Rare Earth Ions In SrTiO3, BaTiO3 and Other Perovskites

1967 ◽  
Vol 23 (6) ◽  
pp. 1321-1332 ◽  
Author(s):  
Hajime Yamamoto ◽  
Shoji Makishima ◽  
Shigeo Shionoya
2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Wojciech A. Pisarski ◽  
Joanna Pisarska ◽  
Marta Kuwik ◽  
Marcin Kochanowicz ◽  
Jacek Żmojda ◽  
...  

AbstractFluoroindate glasses co-doped with Pr3+/Er3+ ions were synthesized and their near-infrared luminescence properties have been examined under selective excitation wavelengths. For the Pr3+/Er3+ co-doped glass samples several radiative and nonradiative relaxation channels and their mechanisms are proposed under direct excitation of Pr3+ and/or Er3+. The energy transfer processes between Pr3+ and Er3+ ions in fluoroindate glasses were identified. In particular, broadband near-infrared luminescence (FWHM = 278 nm) associated to the 1G4 → 3H5 (Pr3+), 1D2 → 1G4 (Pr3+) and 4I13/2 → 4I15/2 (Er3+) transitions of rare earth ions in fluoroindate glass is successfully observed under direct excitation at 483 nm. Near-infrared luminescence spectra and their decays for glass samples co-doped with Pr3+/Er3+ are compared to the experimental results obtained for fluoroindate glasses singly doped with rare earth ions.


1965 ◽  
Vol 20 (6) ◽  
pp. 835-837 ◽  
Author(s):  
Shyama P. Sinha

The room temperature luminescence spectra of the monoterpyridyl chelates of trivalent samarium, dysprosium and thulium have been studied in solid state by exciting with monochromatic radiation of 3200 Å. The spectra of these chelates show intra f → f fluorescent transitions of the chelated rare earth ions as well as the molecular band fluorescence. The “bottleneck” nature of the energy transfer from the nitrogen containing heterocyclic ligands to the coordinated rare earth ions is proposed. The fluorescence data of mono-terpyridyl chelates have been compared with those of bis-dipyridyl one.The phosphorescence spectrum of terpyridyl has also been investigated. The lowest triplet state of the free ligand is found at 22 940 cm-1 above the ground level. The phosphorescence lifetime of terpyridyl is about 2 sec


Author(s):  
A. P. Mar`in ◽  
U. A. Mar`ina ◽  
V. A. Vorob`ev ◽  
R. V. Pigulev

The paper presents the results of a study of the luminescent properties of calcium gallate activated by trivalent rare earth ions Yb3+ and Er3+. IR luminescence spectra of samples with a single activator Ca1‑хYbxGa2O4,Ca1‑хErxGa2O4 were studied when excited by radiation sources with a wavelength of 940 and 790 nm, respectively. The dependence of the luminescence intensity of samples on the concentration of rare earth ions is obtained. When the two-activator composition of Ca1‑х‑yYbxEryGa2O4 is excited by a semiconductor laser diode with a wavelength of 940 nm, IR luminescence is registered in the regions of 980-1100 nm and 1450-1670 nm. The radiation in these bands corresponds to electronic transitions in Yb3+ and Er3+ ions, respectively. For a luminescence band with a maximum at a wavelength of 1540 nm, the excitation spectra were measured, the maximum intensity is at the wavelengths: 930, 941, 970, 980 nm. The dependence of the IR luminescence intensity of a solid solution of Ca1‑х‑yYbxEryGa2O4 on the concentration of Er3+ ions was studied. With an increase in the concentration of Er3+ ions in the luminescence spectra, there is a redistribution in the intensity of the bands belonging to Yb3+ and Er3+ ions, which indicates the presence of energy transfer processes between these ions. The kinetics of IR luminescence attenuation was studied for series with one and two activators: Ca1‑хYbxGa2O4,Ca1‑хErxGa2O4, Ca1‑х‑yYbxEryGa2O4. It is established that the luminescence attenuation occurs mainly according to the exponential law, which indicates the predominance of the intracenter luminescence mechanism in the studied structures. Based on the analysis of the excitation and luminescence spectra of experimental samples, conclusions are made about the interaction of Yb3+ and Er3+ activator ions in the crystal lattice of calcium gallate.


2020 ◽  
Vol 62 (5) ◽  
pp. 800
Author(s):  
В.А. Трепаков ◽  
А.П. Скворцов ◽  
Z. Potuvcek ◽  
L. Jastrabik ◽  
A. Dejneka

Abstract In KTaO_3:Er crystals, we observed a temperature shift, unusual for rare earth impurities, for narrow zero-phonon luminescence lines, due to the ^4 S _3/2 → ^4 I _13/2, ^4 F _9/2 → ^4 I _15/2, and ^4 S _3/2 → ^4 I _15/2 transitions in Er^3+ impurity ions. The magnitude of the shifts turned out to be comparable with the large shifts of the R lines of the Cr^3+ luminescence in SrTiO_3:Cr and KTaO_3:Cr crystals, that is, substantially larger than that for the three-charged rare earth ions usually observed in the   f – f   luminescence spectra in ionic crystals.


1973 ◽  
Vol 51 (4) ◽  
pp. 382-388 ◽  
Author(s):  
R. W. Ward ◽  
P. W. Whippey

The X-ray luminescence and thermoluminescence due to Eu ions in CaF2 have been investigated. Thermoluminescent glow curves of CaF2 single crystals containing several different concentrations of europium have been measured between 4.2 K and 400 K. Spectral analysis of the two major glow peaks at 92 K and 240 K shows that the luminescence is due mainly to Eu2+ ions. The available evidence suggests the thermoluminescence of Eu2+ in CaF2 is a hole-type recombination process similar to the generally accepted mechanism for thermoluminescence from trivalent rare-earth ions in CaF2. In addition to the Eu2+ emission, lines are observed at lower energies in the X-ray luminescence spectra due to Eu3+ ions in at least three different symmetry sites.


2016 ◽  
Vol 846 ◽  
pp. 131-136
Author(s):  
Nurhafizah Hasim ◽  
Md Supar Rohani ◽  
Md Rahim Sahar ◽  
Sib Krishna Ghoshal

Achieving tuneable photoluminescence via controlled co-doping of rare earth ions in lithium niobate based glasses are challenging. A series of Er3+/ Nd3+ co-doped tellurite glasses of composition (70-x-y) TeO2 – 15 Li2CO3 – 15 Nb2O5 – (x) Er2O3 – (y) Nd2O3 with x = 0; 1.0 mol % and 0 ≤ y ≤ 1.0 mol % are prepared using melt quenching technique. The influence of co-dopants on the emission properties is analyzed and discussed using partial energy level diagram of rare earth ions. The dopants concentration dependent physical properties such as refractive index, molar volume, density, polarizability and molar refractions are determined. The down-converted luminescence spectra for 2G9/2 à4I9/2 transition reveal a strong green emission band centred at 497 nm is attributed to the energy transfer from erbium to neodymium ion. The emission spectra exhibit five prominent peaks centred at 497, 539, 553, 616 and 634 nm corresponding to the transitions from 2H11/2, 4S3/2 and 4F9/2 excited states to the ground state of Er3+ ion and the transitions from 2G9/2, 2G7/2, 2H11/2 and 4F9/2 excited states to ground state of Nd3+ ion. The highest intensity is achieved for x = y = 1.0 mol%. The excellent luminescence response suggests that our glasses may be nominated for solid state lasers and other photonic applications.


2021 ◽  
Vol 9 ◽  
Author(s):  
Roman Ziniuk ◽  
Artem Yakovliev ◽  
Hui Li ◽  
Guanying Chen ◽  
Junle Qu ◽  
...  

Rare-earth doped nanoparticles (RENPs) have been widely used for anti-counterfeiting and security applications due to their light frequency conversion features: they are excited at one wavelength, and they display spectrally narrow and distinguished luminescence peaks either at shorter wavelengths (i.e., frequency/energy upconversion) or at longer wavelengths (frequency/energy downconversion). RENPs with a downconversion (DC) photoluminescence (PL) in short-wave infrared (SWIR) spectral range (~1,000–1,700 nm) have recently been introduced to anti-counterfeiting applications, allowing for multilevel protection based on PL imaging through opaque layers, due to a lesser scattering of SWIR PL emission. However, as the number and spectral positions of the discrete PL bands exhibited by rare-earth ions are well-known, it is feasible to replicate luminescence spectra from RENPs, which results in a limited anti-counterfeiting security. Alternatively, lifetime of PL from RENPs can be used for encoding, as it can be finely tuned in broad temporal range (i.e., from microseconds to milliseconds) by varying type of dopants and their content in RENPs, along with the nanoparticle morphology and size. Nevertheless, the current approach to decoding and imaging the RENP luminescence lifetimes requires multiple steps and is highly time-consuming, precluding practical applications of PL lifetime encoding for anti-counterfeiting. Herein, we report the use of a rapid lifetime determination (RLD) technique to overcome this issue and introduce real-time imaging of SWIR PL lifetime for anti-counterfeiting applications. NaYF4:20% Yb, x% Er (x = 0, 2, 20, 80)@NaYF4 core@shell RENPs were synthesized and characterized, revealing DC PL in SWIR region, with maximum at ~1,530 nm and PL lifetimes ranging from 3.2 to 6 ms. Imaging of the nanoparticles with different lifetimes was performed by the developed time-gated imaging system engaging RLD method and the precise manipulation of the delay between the excitation pulses and camera gating windows. Moreover, it is shown that imaging and decrypting can be performed at a high rate (3–4 fps) in a cyclic manner, thus allowing for real-time temporal decoding. We believe that the demonstrated RLD-based fast PL lifetime imaging approach can be employed in other applications of photoluminescent RENPs.


2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
M. A. Marzouk ◽  
H. A. ElBatal ◽  
Y. M. Hamdy ◽  
F. M. Ezz-Eldin

Glasses with the Na2O–ZnO–P2O5 composition and doped with single CeO2, Sm2O3, or mixed dopants were melted and studied. Collective optical, photoluminescence, and FT-infrared spectral studies were carried out. CeO2-doped glasses show two extra UV absorption bands due to Ce4+ and Ce3+ ions while Sm2O3-doped samples reveal pronounced peaks collected into two segments from 367 to 472 nm and from 950 to 1623 nm which are characteristic of absorption from Sm3+ ions. The mixed dopants glasses show combined UV-visible–near-IR absorption peaks due to cerium (Ce4+, Ce3+) ions and samarium (Sm3+) ions. The photoluminescence spectra (PL) of the single CeO2-doped and Sm2O3-doped glasses and even the mixed dopant sample reveal luminescence spectra after excitation which are characteristic of the rare-earth ions. The intensities for both excited or emitted peaks are found to increase with the increase of the rare-earth percent. FTIR spectra of the glasses show pronounced vibrational peaks related to phosphate groups (Q2 and Q3 units) in accordance with the P2O5 percent (70 mol %).


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