Coherent Laser Induced Synthesis of Rare Earth Doped Nanocrystallites of 50PbO-25Bi2_2O3_3-20Ga2_2O3_3-5BaO

A principal possibility of formation the nanostructures on the surfaces of 50PbO-25Bi$_2$O$_3$-20Ga$_2$O$_3$-5BaO (doped by Eu3+, Er3+, Dy3+) is demonstrated by using multi-coherent beams. As a sources of the photoinducing coherent light we have used nanosecond Nd:YAG and Er:Yb lasers generating at 1064 nm and 1540 nm, respectively. The morphology of the photoinduced surfaces is sensitive to the type of rare earth ions. The thickness of the layer was about 20-30 nm. Possible mechanisms are explained by coherent photoinduction of the valence electrons

CdS Nanocrystallines: Synthesis, Structure and Nonlinear Optical Properties

We report the synthesis, structure and nonlinear optical properties of cadmium sulphide (CdS) nanocrystallines (NCs) synthesized electrochemically both with and without detergent ATLAS G3300. Relevant structural and morphological features are explored by X-ray diffraction and scanning electron microscopy (SEM) techniques. The efficiency of the second harmonic generation (SHG) appears to be strongly dependent on the energy density of the incident fundamental laser radiation and NC sizes.Comment: 2020 IEEE 15th International Conference on Advanced Trends in Radioelectronics, Telecommunications and Computer Engineering (TCSET), Conference Location: Lviv-Slavske, Ukraine, 25-29 February 2020, 5 pages, 8 figures, 3 table

Er/Pr-codoped borotellurite glasses as efficient laser operated nonlinear optical materials

We have discovered a rare opportunity to operate by the SHG at fundamental wavelength 10.6 μm of microsecond CO2 laser during simultaneous irradiation by 1064/532 nm bicolor laser beams of (60-x-y)TeO2-10B2O3-10BaO-10ZnO-10Na2O-(x)Er2O3-(y)Pr6O11 (x = 0.5, 1.0; y = 0); (x = 0; y = 0.1, 0.2, 0.3, 0.4, 0.5); (x = 0.5,1.0; y = 0.1, 0.2, 0.3, 0.4, 0.5) (mol%) glasses. The effect has shown a drastic sensitivity of the effect to the Er/Pr ratio. The effect exists only during the simultaneous illumination and applied dc-electric field at 5 kV/cm. Only completely reversible changes were observed. The effect is a consequence of photopolarization during the bicolor coherent laser beams and its efficiency is determined by the transfer of excitation between the Er and Pr ions

Effect of alkali/mixed alkali metal ions on the thermal and spectralcharacteristics of Dy3+:B2O3-PbO-Al2O3-ZnO glasses

Thermal and spectroscopic features of 50 B2O3–10 PbO–10 Al2O3–10 ZnO–(x) Li2O–(y) Na2O–(z) K2O–1.0 Dy2O3 (mol %) (x = 19, y = 0, and z = 0; x = 0, y = 19, and z = 0; x = 0, y = 0, and z = 19; x = 9.5, y = 9.5, and z = 0; x = 9.5, y = 0, and z = 9.5; x = 0, y = 9.5, and z = 9.5) glasses, that were fabricated by utilizing melt-quenching approach, are investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), optical absorption, photoluminescence excitation (PLE), photoluminescence (PL), and PL decay lifetimes. PL spectra for all the Dy3 +-doped samples show emission bands at 453 nm (blue), 482 nm (blue), 573 nm (yellow), 662 nm (red), and 752 nm (red) corresponding to the 4I15/2 → 6H15/2, 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2, and 4F9/2 → 6H9/2 transitions, respectively, upon excitation at 350 nm. Here, Dy3 +: Li–Na glass shows the highest PL intensity for all identified emissions. The yellow-to-blue (Y/B) emission intensity ratio (varied within the range 1.257–1.376), CIE chromaticity coordinates (x,y) (slight variation between (0.3410, 0.3802) and (0.3495, 0.3872), and correlated color temperatures (CCTs) (changed from 4953 K to 5212 K) are calculated following the PL spectra. Dy3 +: 4F9/2 decay curves show non-exponential behavior and are fitted by the Inokuti-Hirayama (I–H) model, where S = 6 shows best fit, indicating dipole-dipole (d-d) interactions for Dy3 + excited (donor) and ground state (acceptor) ions

Optical and dielectric studies for Tb3+/Sm3+ co-doped borate glasses for solid-state lighting applications

Singly doped Tb3+ and Sm3+ ions along with co-doped Tb3+/Sm3+ borate glasses have been fabricated by melt quenching technique. Both TGA and DSC curves were measured for exploration of thermal properties. Among all Tb3+/Sm3+ co-doped glasses, the (Tb0.5-Sm0.5) glass shows the highest emission intensity with respect to others. A total of five emission bands where two are from Tb3+ transitions corresponding to 488 nm (blue) (5D4 → 7F6) and 543 nm (green) (5D4 → 7F5) are found. Three emission bands from Sm3+ at 563 nm (green), 599 nm (orange-red) and 645 nm (red) according to 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, and 4G5/2 → 6H9/2 electronic transitions are identified. The calculated CIE chromaticity (x,y) coordinates for singly doped Tb3+ (Tb0.5) green emission, singly doped Sm3+ (Sm0.5) orange-red emission, and co-doped Tb3+/Sm3+ (Tb0.5-Sm0.5) yellow emission are (0.343, 0.584), (0.607, 0.389), and (0.438, 0.515), respectively, following the CIE 1931 chromaticity diagram. Further, dielectric features were studied for the Tb3+/Sm3+co-doped glass (Tb0.5-Sm0.5) in terms of dielectric constant, dielectric loss and AC conductivity with the increasing of frequency and temperature

Investigation of structural, thermal properties and shielding parameters for multicomponent borate glasses for gamma and neutron radiation shielding applications

Multicomponent borate glasses with the chemical composition (60 − x) B2O3–10 Bi2O3–10 Al2O3–10 ZnO–10 Li2O–(x) Dy2O3 or Tb4O7 (x = 0.5 mol%), and (60 − x − y) B2O3–10 Bi2O3–10 Al2O3–10 ZnO–10 Li2O–(x) Dy2O3–(y) Tb4O7 (x = 0.25, 0.5, 0.75, 1.0, 1.5, and 2.0 mol%, y = 0.5 mol%) have been fabricated by a conventional melt-quenching technique and were characterized by X-ray diffraction (XRD), Attenuated Total reflectance-Fourier transform Infrared (ATR-FTIR) spectroscopy, Raman spectroscopy, thermo-gravimetric analysis (TGA), and differential scanning calorimetry (DSC). Also, the radiation shielding parameters such as mass attenuation coefficient (μ/ρ), half value layer (HVL), mean free path (MFP) and exposure buildup factor (EBF) values were explored within the energy range 0.015 MeV–15 MeV using both XCOM and MCNPX code to determine the penetration of gamma and neutron radiations in the prepared glasses. The main BO3, BO4, BiO6, and ZnO4 structural units and AlOAl bonds were confirmed by ATR-FTIR and Raman spectroscopy. Weight loss, and the glass transition (Tg), onset crystallization (Tx), and crystallization (Tc) temperatures were determined from TGA and DSC measurements, respectively. The stability of the glass against crystallization (ΔT) is varied within the temperature range 114–135 °C for the studied glasses. In addition, the shielding parameters like the (μ/ρ) values investigated using both MCNPX Monte Carlo and XCOM software are in good agreement with each other. The (μ/ρ) values calculated using XCOM software were used to evaluate the HVL and MFP in the photon energy range 0.015 MeV–15 MeV. It is found that all the synthesized glasses possess better shielding properties than ordinary concrete, zinc oxide soda lime silica glass and lead zinc phosphate glass indicating the high potentiality of the prepared glasses to be utilized as radiation shielding materials

PHYSICAL ORIGIN OF PHOTOVOLTAIC EFFECTS IN CYANO SUBSTITUTED PYRAZOLOQUINOLINES

International audienceWe have achieved an increase of efficiency in the single layered photovoltaic cells up to 0.44 % for the cyano substituted pyrazoloquinolines. Principal role in the increase of the open circuit voltage Voc play state dipole moments. However, there exist several discrepancies which are caused by position of the chromophore HOMO levels. We have found that incorporation of the highly polarized cyano group leads to enhancement of the state dipole moments and open circuit voltage up to 1.107 V. That means the enhancement at least by 40 % compared to the pyrazoloquinoline without the cyano groups. Principal explanations are given

Investigations of the TlInp2Se6–In4(P2Se6)3 System and its Optical Properties

The equilibrium phases were investigated and the corresponding phase diagram constructed for the TlInP2Se6–In4(P2Se6)3 system from physical and chemical analyses, namely differential thermal analysis (DTA), X-ray diffraction (XRD), and microstructural analysis (MSA). It was established that this system belongs to the eutectic type and is characterized by the formation of boundary solid phases containing complex compounds. Single crystals of the compounds TlInP2Se6 and In4(P2Se6)3 were grown using the Bridgman method. Both crystals were found to exhibit diffuse reflection spectra and photoinduced dependence of birefringence at various IR wavelengths generated by CO2 laser irradiation. Birefringence properties were investigated using the Senarmont method

Band Structure Simulations of the Photoinduced Changes in the MgB2:Cr Films

An approach for description of the photoinduced nonlinear optical effects in the superconducting MgB2:Cr2O3 nanocrystalline film is proposed. It includes the molecular dynamics step-by-step optimization of the two separate crystalline phases. The principal role for the photoinduced nonlinear optical properties plays nanointerface between the two phases. The first modified layers possess a form of slightly modified perfect crystalline structure. The next layer is added to the perfect crystalline structure and the iteration procedure is repeated for the next layer. The total energy here is considered as a varied parameter. To avoid potential jumps on the borders we have carried out additional derivative procedure

The Separation of the Mn₁₂ Single-Molecule Magnets onto Spherical Silica Nanoparticles

The Mn12 single-molecule magnets (SMMs) could be attached to the surface of spherical silica for the first time with a high probability. This allowed separation of the individual molecular magnets and direct microscopic observation of the SMMs. We described in detail how to fabricate such a composite material. The synthesis procedure proposed here is simple and efficient. We confirmed the efficiency of the method by transmission electron microscopy (TEM): single-molecule magnets were visible at the surface of a silica substrate. Based on TEM observation, we described how the molecules anchor to the surface of silica (the geometry of the magnetic molecule in regard to the surface of the substrate). The SQUID magnetometry showed that single-molecule magnet behaviour is kept intact after grafting. The attachment of the single-molecule magnets to the surface of silica allows to investigate their properties as separate molecules. This is particularly important in the analysis of magnetic properties such as magnetic states of the separated SMMs, their mutual interactions, and the influence of a silica support