Saturation effects in the excitation spectra of rare-earth ions

1994 ◽  
Vol 62 (5) ◽  
pp. 189-201 ◽  
Author(s):  
C. de Mello Donegá ◽  
A. Meijerink ◽  
G. Blasse
Keyword(s):  
Rare Earth ◽  
Rare Earth Ions ◽  
Excitation Spectra ◽  
Saturation Effects

scholarly journals Kinetics of luminescence calcium gallate activated by Yb3+, Er3+ ions

2020 ◽  
Vol 23 (3) ◽  
pp. 213-221
Author(s):  
A. P. Mar`in ◽  
U. A. Mar`ina ◽  
V. A. Vorob`ev ◽  
R. V. Pigulev
Keyword(s):  
Rare Earth ◽  
Luminescence Intensity ◽  
Luminescent Properties ◽  
Rare Earth Ions ◽  
Luminescence Spectra ◽  
Excitation Spectra ◽  
Semiconductor Laser Diode ◽  
Intracenter Luminescence ◽  
Trivalent Rare Earth ◽  
Kinetics Of

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.

Mixed-Phase Crystallization and Visible Fluorescence in Rare-Earth Ions Doped Germanate Glass-Ceramics

2011 ◽  
Vol 399-401 ◽  
pp. 904-907 ◽  
Author(s):  
Yu Hua Li ◽  
Xiang Ling Zhang ◽  
Cun Xi Fan ◽  
Ming Liu ◽  
Bin Zhai ◽  
...  
Keyword(s):  
Rare Earth ◽  
Glass Ceramics ◽  
Heat Treating ◽  
Rare Earth Ions ◽  
Blue Laser ◽  
Excitation Spectra ◽  
Germanate Glass ◽  
Bluish Green ◽  
Doped Glass ◽  
Rare Earth Doped Glass

Rare-earth doped glass-ceramics were prepared by heat-treating the precursor germanate glasses. The crystalline phases of the glass-ceramics were assigned to be NaAlGeO4 (NAG) and Mg2GeO4 (MG), and the primary particle sizes were derived to be ~31 and ~32nm, respectively. The secondary particle size of crystal grains was estimated to be ~30µm, and the large grain size is owing to the particles aggregation. Under 254 and 365nm radiation, Sm3+-doped glass-ceramics exhibit orange and reddish-orange fluorescences, and Eu-doped glass-ceramics present red and purplish-red lights, respectively. The investigation results of excitation spectra indicate that the Sm3+- and Eu-doped NAG-MG glass-ceramics can be excited efficiently by commercial UV and blue laser diodes, as well as blue and bluish-green LEDs.

scholarly journals Effect of Rare-Earth Ions on the Optical and PL Properties of Novel Borosilicate Glass Developed from Agricultural Waste

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5607
Author(s):  
Aiyeshah Alhodaib ◽  
Omnia Ibrahim ◽  
Suzy Abd El All ◽  
Fatthy Ezzeldin
Keyword(s):  
Rare Earth ◽  
Agricultural Waste ◽  
Visible Spectrum ◽  
Rare Earth Oxides ◽  
Rare Earth Ions ◽  
Raw Material ◽  
Molar Ratio ◽  
Borosilicate Glasses ◽  
Excitation Spectra ◽  
Novel Structure

There is considerable attention devoted to the use of agricultural waste as a raw material substitute for commercial silica in the development of borosilicate glasses doped with rare earth oxides. Here, we present a novel structure for borosilicate glasses made from rice husk ash with a 25% molar ratio of extracted SiO2 and doped with neodymium (GRN) or dysprosium (GRD). Adding rare earth oxides to borosilicate glasses by the melt quenching method enhanced optical transmission due to the presence of their tetrahedral geometries. GRN samples showed few bands near zero, which constitutes good utility for band rejection filters in image devices, and the samples exhibited energy values ranging from 3.03 to 3.00 eV before and after gamma irradiation. Optical transmissions of GRD samples showed peaks at 25,974, 22,172, 13,333, 11,273, 9302, 7987, and 6042 cm−1. Deterioration in transmittance was observed when the investigated samples were exposed to irradiation doses of 20 and 50 kGy in the wavenumber range of 12,500 to 50,000 cm−1; however, different behaviors after irradiation with 50 kGy caused an increase in transparency in comparison to 20 kGy irradiation, which was pronounced for higher wavenumbers (greater than 12,500 cm−1). Photoluminescence emission and excitation spectra of the glass-doped Nd3+ (GRN) and glass-doped Dy3+ (GRD) samples were determined. GRD exhibited emission in the blue and yellow regions of the visible spectrum, which gave a white flash of light. Chromaticity coordinate (CIE) measurements of GRD samples indicated the origin of its luminous color relative to the standard white light region.

scholarly journals Photoluminescence Properties of Eu3+ and Ce3+ Activated Calcium Chlorophosphate Via Combustion Synthesis Method

2016 ◽  
Vol 1 (1-2) ◽  
pp. 10-15
Author(s):  
Nahida Baig ◽  
N. S. Dhoble ◽  
N. S. Kokode ◽  
S. J. Dhoble
Keyword(s):  
Rare Earth ◽  
Combustion Synthesis ◽  
Synthesis Method ◽  
Ultra Violet ◽  
Luminescent Properties ◽  
Rare Earth Ions ◽  
Excitation Spectra ◽  
Pl Emission ◽  
Narrow Bands ◽  
Uv Range

Calcium chlorophosphate (Ca2PO4Cl) phosphors, activated by rare earth ions Eu3+ and Ce3+ were prepared by urea assisted combustion synthesis technique and their characterization and luminescent properties were studied. The synthesized phosphors were investigated by powdered XRD, SEM and Photoluminescence characterization (PL) methods. PL excitation spectra of Ca2PO4Cl:Eu3+/Ce3+ phosphor exhibit narrow bands in the near ultra violet (n-UV) range, and the PL emission spectra of Ca2PO4Cl: Eu3+/Ce3+ phosphor shows sharp narrow bands typical of rare earth ions. The bands observed in the PL emission and excitation spectra of Ca2PO4Cl: Eu3+/Ce3+ phosphors can be ascribed to the electronic transitions within 4f configurations of rare earth ions. The excitation peaks for Ca2PO4Cl: Eu3+ is in n-UV range. The obtained results suggest that these phosphors may be favorable for lamp industry.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

Structural, Morphological and Magnetic Characterization of Sm-substituted Ni-Zn Ferrite

2020 ◽  
Vol 10 (2) ◽  
pp. 152-156 ◽  
Author(s):  
Muhammad Hanif bin Zahari ◽  
Beh Hoe Guan ◽  
Lee Kean Chuan ◽  
Afiq Azri bin Zainudin
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Saturation Magnetization ◽  
Sol Gel ◽  
Magnetic Behavior ◽  
Rare Earth Ions ◽  
Ion Concentration ◽  
Zn Ferrite ◽  
Auto Combustion ◽  
Combustion Technique

Background: Rare earth materials are known for its salient electrical insulation properties with high values of electrical resistivity. It is expected that the substitution of rare earth ions into spinel ferrites could significantly alter its magnetic properties. In this work, the effect of the addition of Samarium ions on the structural, morphological and magnetic properties of Ni0.5Zn0.5SmxFe2-xO4 (x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) synthesized using sol-gel auto combustion technique was investigated. Methods: A series of Samarium-substituted Ni-Zn ferrite nanoparticles (Ni0.5Zn0.5SmxFe2-xO4 where x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by sol-gel auto-combustion technique. Structural, morphological and magnetic properties of the samples were examined through X-Ray Diffraction (XRD), Field-Emission Scanning Electron Microscope (FESEM) and Vibrating Sample Magnetometer (VSM) measurements. Results: XRD patterns revealed single-phased samples with spinel cubic structure up to x= 0.04. The average crystallite size of the samples varied in the range of 41.8 – 85.6 nm. The prepared samples exhibited agglomerated particles with larger grain size observed in Sm-substituted Ni-Zn ferrite as compared to the unsubstituted sample. The prepared samples exhibited typical soft magnetic behavior as evidenced by the small coercivity field. The magnetic saturation, Ms values decreased as the Sm3+ concentration increases. Conclusion: The substituted Ni-Zn ferrites form agglomerated particles inching towards more uniform microstructure with each increase in Sm3+ substitution. The saturation magnetization of substituted samples decreases with the increase of samarium ion concentration. The decrease in saturation magnetization can be explained based on weak super exchange interaction between A and B sites. The difference in magnetic properties between the samples despite the slight difference in Sm3+ concentrations suggests that the properties of the NiZnFe2O4 can be ‘tuned’, depending on the present need, through the substitution of Fe3+ with rare earth ions.

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