Activation of Lead Fluoride Room Temperature Luminescence by Structural Modifications

1994 ◽  
Vol 348 ◽  
Author(s):  
D.L. Alov ◽  
A.V. Bazhenov ◽  
V.K. Egorov ◽  
G.A. Emelchenko ◽  
N.V. Klassen ◽  
...  
Keyword(s):  
Room Temperature ◽  
Structural Characteristics ◽  
Structural Defects ◽  
Luminescence Spectra ◽  
Lead Fluoride ◽  
Light Emitting ◽  
X Ray ◽  
Structural Modifications ◽  
Excited Luminescence ◽  
Room Temperature Luminescence

ABSTRACTThe connection of lead fluoride luminescence properties with its structural characteristics has been studied. Single crystals of the cubic and orthorombic phases, cubic and orthorombic powders, pressure compacted orthorombic ceramics, plastically deformed crystals were used. The photo- and X-ray excited luminescence spectra have been investigated. The experimental results have shown that the room temperature luminescence of lead fluoride can be accounted for local light emitting centers which are produced by the intrinsic structural defects in the orthorombic lead fluoride.

Comparative Studies of Optical Spectra in PbF2 at Different Excitations

1994 ◽  
Vol 348 ◽  
Author(s):  
V. K. Egorov ◽  
N.V. Klassen ◽  
V.D. Negrii ◽  
V.M. Prokopenko ◽  
S.Z. Shmurak ◽  
...  
Keyword(s):  
Comparative Studies ◽  
Room Temperature ◽  
Spectral Characteristics ◽  
Optical Spectra ◽  
Lead Fluoride ◽  
X Ray ◽  
Luminescence Centers ◽  
Room Temperature Luminescence ◽  
Α Particles

ABSTRACTThe spectral characteristics for cubic and orthorhombic lead fluoride excited by light with energies of 5–2.5 eV, X-ray, and α-particles were studied. It is shown that the room temperature luminescence in orthorhombic lead fluoride is connected with resonance excitations of some luminescence centers. Possible models of the centers responsible for this phenomenon are proposed.

Investigations on the Rare Earth Terpyridyl System

1965 ◽  
Vol 20 (6) ◽  
pp. 835-837 ◽  
Author(s):  
Shyama P. Sinha
Keyword(s):  
Rare Earth ◽  
Room Temperature ◽  
Free Ligand ◽  
Ground Level ◽  
Phosphorescence Spectrum ◽  
Rare Earth Ions ◽  
Luminescence Spectra ◽  
Heterocyclic Ligands ◽  
Phosphorescence Lifetime ◽  
Room Temperature Luminescence

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

X-ray diffraction single-crystal structure characterization of iron ludwigite from room temperature to 15 K

2006 ◽  
Vol 39 (1) ◽  
pp. 42-45 ◽  
Author(s):  
M. Mir ◽  
Jan Janczak ◽  
Y. P. Mascarenhas
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Structural Characteristics ◽  
Density Wave ◽  
Charge Ordering ◽  
Structure Characterization ◽  
Dimensional Structure ◽  
X Ray ◽  
Extra Electron ◽  
A Charge

Iron ludwigite exhibits a superstructure between 283 and 144 K. Anomalies in its transport properties are due to a structural transition related to a charge-ordering phenomenon in the low-dimensional structure. This ordering produces a commensurate transversal charge density wave in the system. To understand these structural characteristics, an X-ray single-crystal diffraction study has been performed at 300 and 15 K. No changes were found in the crystalline structure, except for contraction of the cell volume. The bond-valence sum for each cation shows that at room temperature each Fe4—Fe2—Fe4 triad is composed of three Fe3+ions with one extra electron per triad, and at 15 K in each Fe4a—Fe2—Fe4btriad the extra electron is accommodated in the Fe4a—Fe2 pair of each triad.

scholarly journals Long Time Stability Investigation for Structural and Magnetic Properties of Ti-doped Barium Ferrite

2019 ◽  
Vol 3 (2) ◽  
pp. 53-57
Author(s):  
Mohammed Abdul Malek Al Saadi
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Structural Characteristics ◽  
Barium Hexaferrite ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Storage Process ◽  
X Ray ◽  
Air Atmosphere ◽  
Long Time

Barium hexaferrite (BHF) (BaFe12O19) and its substituted derivatives have been considered as the most potential magnetic candidates with considerable chemical stability and physiochemical characteristics. BHF with x ferrite ions substituted by titanium (Ti-doped BTHF) (BaTixFe12-xO19) (x=1 and x=3) was prepared from ferric oxide (Fe2O3), barium oxide (BaO), and titanium oxide (TiO2) of purity >98%. The materials were mixed with deionized water and then dried at 1100°C and 1200°C overnight. For the formation of BaFe12O19 phase, the mixture was annealed at a rate of 10°C/min in static air atmosphere until reaching 1200°C and then maintained for 10 h. Structural properties of these samples were measured using X-ray diffraction (XRD) and scanning electron microscopy, while magnetic properties were measured using vibrating sample magnetometer (VSM) device. Magnetic and structural characteristics are investigated after preserving Ti-doped BHF samples at room temperature and ambient conditions for 12 years. The samples are characterized using the same previous techniques to find out the possible effect of long period storage on their properties. The results showed that the storage process has little effect on these properties where the granular size increased due to increased oxidation. XRD tests also showed the absence of Ti at low ratios due to increased oxidation of ferrite. VSM results showed increased magnetic properties after storage due to increased iron oxide.

scholarly journals Структура R-=SUB=-1-=/SUB=- и R-=SUB=-2-=/SUB=- полос изотопов иона Cr-=SUP=-3+-=/SUP=- в монокристалле рубина при комнатной температуре

2021 ◽  
Vol 129 (4) ◽  
pp. 494
Author(s):  
В.С. Аракелян ◽  
Т.И. Бутаева ◽  
П.Г. Мужикян ◽  
Д.Г. Заргарян ◽  
Р.Б. Костанян
Keyword(s):  
Stable Isotopes ◽  
Comparative Analysis ◽  
Laser Diode ◽  
Room Temperature ◽  
Selective Excitation ◽  
Luminescence Spectra ◽  
Halogen Lamp ◽  
Combined Structure ◽  
Absorption And Luminescence Spectra ◽  
Excited Luminescence

Abstract. The absorption and luminescence spectra of the R1 and R2 bands in a ruby Al2O3:Cr3+ (0,05%) single crystal at room temperature were studied. The luminescence bands have been obtained both by excitation of the crystal by the radiation of a halogen lamp and by selective excitation of the two upper levels of the 2T1 state using the radiation of a laser diode with a tunable wavelength (656-662 nm). In the spectra of selectively excited luminescence bands, four different displacements of the R1 and R2 bands and four different distances between these bands have been detected, the change of which is a multiple of ~ 0.52 cm-1. A detailed comparative analysis of the obtained spectra of the luminescence bands and their absorption allowed us to determine the combined structure of each of the R1 and R2 bands, formed by additional doublets of these bands of all four stable isotopes of ions 50Cr3+, 52Cr3+, 53Cr3+ and 54Cr3+. The splitting of the obtained doublets varies from 7.04 to 9.14 cm-1 depend on the mass of the isotope

Synthesis, Crystal Structure, Luminescence, and Nonlinear Optical Properties of 2-[(E)-[[4-[2-(4-Methoxyphenyl)ethynyl]phenyl] imino]methyl]-4- [(E)-phenyldiazenyl]phenol

2020 ◽  
Vol 17 (8) ◽  
pp. 618-623
Author(s):  
Sagar Subhash Mohite ◽  
Aditya Babasaheb Patil-Deshmukh ◽  
Sanjay Shamrao Chavan
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Nonlinear Optical ◽  
Room Temperature ◽  
Second Harmonic ◽  
Monoclinic Structure ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Shg Efficiency ◽  
Room Temperature Luminescence

2-((E)-((4-((4-methoxyphenyl)ethynyl)phenyl)imino)methyl-4-((E)phenyldiazenyl)phenol (1) have been synthesized and characterized. X-ray single crystal diffraction study of the compound 1 reveal a monoclinic structure. Room temperature luminescence is observed for 1 in CH2Cl2 solution due to π* → π transition. The SHG efficiency by Kurtz powder technique indicating the compound 1 displayed the second harmonic generation (SHG) property.

Photoluminescence and Structural Characteristics of SnO2 Nanopetals Synthesized by Thermal Evaporation

2010 ◽  
Vol 152-153 ◽  
pp. 697-701
Author(s):  
Bing Wang ◽  
Ling Li
Keyword(s):  
Room Temperature ◽  
Thermal Evaporation ◽  
Structural Characteristics ◽  
The Self ◽  
Silicon Substrates ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Room Temperature Photoluminescence ◽  
Sno2 Nanostructure

A new nanostructure, (2D) nanopetal of SnO2, has been grown on single silicon substrates by Au-Ag alloying catalyst assisted carbothermal evaporation of SnO2. Field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD) and Raman are employed to identify the morphology and structure of the synthesized productions. Room-temperature photoluminescence (PL) is used to characterize the luminescence of SnO2 nanostructure. Three new peaks at 356, 450 and 489 nm in the measured photoluminescence spectra are observed, implying that more luminescence centers exist in SnO2 nanopetals due to nanocrystals and defects. The growth of the SnO2 nanopetals is discussed on the basis of the self-catalyst mechanism.

Selective Luminescence Spectroscopy of Poly(p-Phenylene) Thin Films at Room Temperature

1995 ◽  
Vol 413 ◽  
Author(s):  
M. A. Drobizhev ◽  
M. N. Sapozhnikov ◽  
V. M. KobryanskII
Keyword(s):  
Thin Films ◽  
Luminescence Spectrum ◽  
Room Temperature ◽  
Selective Excitation ◽  
Luminescence Spectroscopy ◽  
Luminescence Spectra ◽  
Model Calculations ◽  
Localization Threshold ◽  
Low Energy Tail ◽  
Room Temperature Luminescence

ABSTRACTSelectively excited room-temperature luminescence spectra are reported for thin films of poly(p-phenylene) (PPP) deposited onto quartz substrata. The spectra exhibit a localization threshold in the low-energy tail of the luminescence excitation band at vloc.= 22400 cm−1, 2200 cm−1 below the maximum of the excitation spectrum. Upon laser excitation at Vex < Vloc., the maximum Vem of the luminescence spectrum shifts linearly with Vex due to selective excitation of polymer segments. It was found that there exists the frequency range where the slope of the Vem vs Vex dependence is smaller than unity, which corresponds to our previous model calculations for the case of selective excitation of chromophores through broad phonon bands. At vex > vloc,, the luminescence spectrum is independent of Vex. This behavior can be explained if one assumes that upon excitation below the localization threshold the luminescence is related to polymer segments directly excited by laser, whereas upon exciting above the threshold the fast energy relaxation takes place from initially excited states to lower-lying states, from which uminescence occurs.

Structural, Magnetic and Microwave Absorbing Properties of Nanosized NiXZn1-xFe2O4 Powders Synthesized by Sol-Gel Technique

2010 ◽  
Vol 148-149 ◽  
pp. 1144-1147
Author(s):  
Xiang Rong Zhu ◽  
Lin Feng Lu ◽  
Hong Lie Shen
Keyword(s):  
Room Temperature ◽  
Structural Characteristics ◽  
Sol Gel ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Gel Technique ◽  
Soft Magnetism

NixZn1-xFe2O4 (x=0.4, 0.6) powders are synthesized by sol-gel technique. The X-ray diffraction (XRD) measurements show their polycrystalline spinel structural characteristics. Both XRD and Atomic Force Microscopy demonstrate the samples are nanosized. At room temperature typical soft magnetism is exhibited by the samples. The reflection attenuation resulting from microwave absorption would reach to 1.9 dBm over the frequency range 6 GHz - 10 GHz when the samples are paved on a 10 cm  10 cm square aluminum plate with a thickness of about 0.35 mm.

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