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

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

Laser-induced piezoelectricity in AgGaGe

Photoinduced changes of piezoelectric coefficients for novel chalcogenide AgGaGe3–xSixSe8 (x = 0.15, 0.3, 0.6, 0.9) single crystals are discovered. The measurements were performed during illumination by cw 532 nm laser (above energy band gap) with power about 400 mW. The relaxation after switching off of the laser beam was studied. Additional temperature dependences of piezoelectric diagonal tensor components were recorded to separate the thermal effect with respect to pure electronic contribution to the photoinduced piezoelectricity. In addition to the photoinduced piezoelectric effect FTIR spectra are studied in order to explore the influence of the thermal contribution. The photoinduced changes with taking into account of temperature contribution have achieved magnitude equal to approximately 50–60% for all the studied samples and the changes were found to be completely reversible. The possible mechanisms for the observed effects are discussed and additional quantum chemical DFT simulations for the principal structural fragments were performed

Nové dibenzothiofenové chromofory s postranním barbiturovým akceptorem

A series of novel chromophores based on central 2,8-disubstituted dibenzothiophene (DBT) or dibenzothiophene-S,S-dioxide (DBTO) has been designed and prepared. The interconnection of DBT(O) central scaffold with two peripheral barbituric acceptors via various pi-spacer allowed significant property tuning of target chromophores. Four new final chromophores and six DBT(O)-intermediates have been successfully synthesized and fully characterized. Experimental and calculated data showed that the fundamental properties are affected by the chromophore A-pi-D-pi-A or A-pi-A-pi-A arrangement (DBT vs. DBTO) and the pi-linker (ethenylene vs. ethynylene). Thorough structure-property relationships have been elucidated and discussed in detail.Byly připraveny nové chromofory na bázi 2,8-disubstituovaného dibenzothiofenu nebo dibenzothiofen-S,S-dioxidu. Spojení centrální jednotky s postranním barbiturovým akceptorem prostřednictvím pi-konjugované spojky zajistilo modulování vlastností chromoforů. Byly syntetizovány čtyři finální chromofory a šest meziproduktů, látky byly plně charakterizovány. Byly u nich studovány vztahy mezi strukturou a vlastnostmi

Insight into the Optoelectronic and Thermoelectric Properties of Mn Doped ZnTe from First Principles Calculation

Using DFT band structure simulations together with semi-classical Boltzmann transport kinetics equations, we have explored the optoelectronic and transport features of MnxZn1−xTe (x = 8% and 16%) crystals. Optimization of the doping and related technological processes it is extremely important for optimization of the technological parameters. The Generalized Gradient Approximation is applied to compute the corresponding band structure parameters. We have applied the Generalized Gradient Approximation Plus U (GGA+U). We have demonstrated that MnxZn1−xTe (x = 8% and 16%) is a direct type band semiconductor with principal energy gap values equal to 2.20 and 2.0 eV for x = 8% and 16%, respectively. The energy gap demonstrates significant decrease with increasing Mn content. Additionally, the origin of the corresponding bands is explored from the electronic density of states. The optical dispersion functions are calculated from the spectra of dielectric function. The theoretical simulations performed unambiguously showed that the titled materials are simultaneously promising optoelectronic and thermoelectric devices. The theoretical simulations performed showed ways for amendment of their transport properties by replacement of particular ions

ThDion: Silná elektronakceptorní jednotka pro push-pull molekuly

A series of new push-pull chromophores based on a combined cyclopenta[c]thiophene-4,6-dione (ThDione) acceptor,N,N-dimethylaniline,N-piperidinylthiophene or ferrocene donors, and ethylene or buta-1,3-dienylene pi-linkers has been designed and synthesized. Utilizing one or two ThDione acceptors afforded linear or branched push-pull molecules. Experimental and theoretical study of their fundamental properties revealed thermal robustness up to 260 degrees C, a electrochemical/optical HOMO-LUMO gap that is tunable within the range of 1.47-2.19/1.99-2.39 eV, and thorough elucidation of structure-property relationships. Compared to currently available portfolio of heterocyclic electron-withdrawing units, ThDione proved to be a powerful and versatile acceptor unit. It imparts significant intramolecular charge transfer and polarizes the pi-system, which results in enhanced (non)linear optical response.Série nových push-pull chromoforů nesoucích akceptorní jednotku na bázi cyklopenta[c]thiofen-4,6-dionu (ThDionu) byla navržena a úspěšně syntetizována. Na základě experimentálních i teoretických studií těchto cílových chromoforů bylo potvrzeno, že ThDion je silnou a univerzální akceptorní jednotkou ve srovnání s aktuálně dostupným portfoliem heterocyklických elektronakceptorních jednotek. ThDion významně přispívá k intramolekulárnímu přenosu náboje a výrazné polarizaci celého π systému, což dále navyšuje (ne)lineární optickou odezvu cílových chromoforů