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Open access

Azeezaa Varsha Mohammed and Suresh Sagadevan

Abstract

L-cysteine hydrogen fluoride (LCHF) single crystals were grown from aqueous solution. Single crystal X-ray diffraction, FT-IR, UV-Vis-NIR, and TG-DTA were used to test the grown crystals. The specimen dielectric and mechanical behaviors were also studied. Powder X-ray diffraction of the grown crystal was recorded and indexed. The optical properties of the LCHF crystal were determined using UV-Vis spectroscopy. It was found that the optical band gap of LCHF was 4.8 eV. The crystal functional groups were identified using FT-IR. Second harmonic generation (SHG) efficiency of the LCHF was three times higher than that of KDP. The dielectric constant, dielectric loss and AC conductivity were measured at different frequencies and temperatures.

Open access

A. Sadoun, S. Mansouri, M. Chellali, N. Lakhdar, A. Hima and Z. Benamara

Abstract

In this work, we have presented a theoretical study of Au/Ni/GaN Schottky diode based on current-voltage (I-V) measurement for temperature range of 120 K to 400 K. The electrical parameters of Au/Ni/GaN, such as barrier height (Φb), ideality factor and series resistance have been calculated employing the conventional current-voltage (I-V), Cheung and Chattopadhyay method. Also, the variation of Gaussian distribution (P (Φb)) as a function of barrier height (Φb) has been studied. Therefore, the modified ((1n(I0T2)-(q2σs022kT2)=1n(AA*)-qB0kT)vs.(1kT)) relation has been extracted from (I-V) characteristics, where the values of ΦB0 and ASiuml* have been found in different temperature ranges. The obtained results have been compared to the existing experimental data and a good agreement was found.

Open access

Tahmineh Jalali, Abdolrasoul Gharaati and Mohammad Rastegar

Abstract

In this paper, employing of one-dimensional magnetophotonic crystals in infrared wavelengths range is considered. For this purpose, magnetophotonic multilayer structures, composed of magnetic defect layer surrounded by dielectric and MO Bragg mirrors, have been proposed. Ce:YIG with an optical thickness in the range of 0 to λs was used as a magnetic material. By using four by four transfer matrix method, the transmittance values and Faraday rotation (FR) angles of these structures were computed. The electric field distribution was obtained by Finite Element Method (FEM). By investigation of transmittance and FR angle of magnetophotonic crystals, it was possible to design the optimized structures with a rotation larger than 30 degrees and high transmittance. Such structures with a few micrometer thickness and fast magneto-optical (MO) responses have the potential to be used in MO devices like integrated photonic elements and sensors.

Open access

S. Abarna and G. Hirankumar

Abstract

Solid polymer electrolytes based on polyvinyl alcohol (PVA) doped with LiPF6 have been prepared using solution casting technique. Electrical properties of prepared electrolyte films were analyzed using AC impedance spectroscopy. The ionic conductivity was found to increase with increasing salt concentration. The maximum conductivity of 8.94 × 10−3 S·cm−1 was obtained at ambient temperature for the film containing 20 mol% of LiPF6. The conductivity enhancement was correlated to the enhancement of available charge carriers. The formation of a complex between the polymer and salt was confirmed by Fourier transform infrared spectroscopy (FT-IR). The optical nature of the polymer electrolyte films was analyzed through UV-Vis spectroscopy.

Open access

Božana Čolović, Danilo Kisić, Bojan Jokanović, Zlatko Rakočević, Ilija Nasov, Anka Trajkovska Petkoska and Vukoman Jokanović

Abstract

Thin films of titanium oxides, titanium oxynitrides and titanium nitrides were deposited on glass substrates by the methods of direct current (DC) and pulsed magnetron sputtering and cathodic arc evaporation. Phase analysis of the deposited films by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) showed the presence of phases with various Ti oxidative states, which indicated a high concentration of oxygen vacancies. The films morphology was investigated by scanning electron microscopy (SEM). Investigations of the films wettability, either with water or ethylene glycol, showed that it depends directly on the concentration of oxygen vacancies. The wettability mechanism was particularly discussed.

Open access

P. Sakthi, R. Rajasekaran and A. Arun

Abstract

An inorganic coordination complex of single crystal containing sodium and aluminum (SA) was grown at room temperature by slow evaporation technique. The crystal was characterized using single crystal X-ray diffraction (XRD), FT-IR, UV-Vis, SHG, SEM, EDX and TG/DTA analyses. The size of the grown crystal was around 17 mm × 15 mm × 5 mm. Both optical and SEM photographs confirmed that the crystal is transparent with smooth surface. The XRD data showed that the crystal belongs to the BCC crystal structure. The crystal shows excellent transparency in the entire region of visible light (cut-off value is 339 cm−1). The dielectric constant as well as dielectric loss of the sample was calculated by varying frequencies at different temperatures and the presence of low dielectric loss proved that this crystal can be used for the NLO application.

Open access

A. Gadalla, M. S. Abd El-Sadek and R. Hamood

Abstract

This paper attempts to describe an effective method for producing a composite of quantum dots consisting of CdSe (core) with CdS (shell). This nanoparticles composite was synthesized from modified organometallic precursors. The sizes of the nanoparticles were estimated from X-ray diffraction data using Debye-Scherer formula and compared with high resolution electron microscopy (HRTEM) and optical spectra. The shape of CdSe/CdS NPs is nearly spherical and revels that the CdS shell with the thickness ~0.6 nm almost fully covers the CdSe core (higher contrast). Using UV-Vis spectroscopy, a systematic red shift in the absorption and emission spectra was observed after the deposition of CdS which confirms the shell growth over the CdSe core. In the CdSe/CdS core/shell structure, the holes are confined to the core, while the electrons are delocalized as a result of similar electron affinities of the core and the shell. The increased time of synthesis resulted in shell thickness increase. The observed properties of prepared CdSe/CdS QDs demonstrate the capability of the nanocomposite for using in the optoelectronics and photonics devices.

Open access

M. Irshad Ahamed and K. Sathish Kumar

Abstract

In this communication, we report on Cu2SnS3 quantum dots synthesized by the solvothermal process using different solvents. The optical properties of the quantum dots are analyzed by UV-Vis-NIR and photoluminescence spectroscopy. The results suggest that Cu2SnS3 material has tunable energy bandgap and appropriate wavelength for fabrication of light emitting diodes and laser diodes as sources for fiber optic communication. They exhibit wide absorption in the near infrared range. Further morphological studies with the use of atomic force microscope confirm the surface topography and the existence of quantum dots. The observed characteristics prove the efficiency of Cu2SnS3 quantum dots for O-band wavelength detection used in fiber optic communication and solar cell applications.

Open access

M. Suresh, S. Asath Bahadur and S. Athimoolam

Abstract

In the present work, a new organic second order NLO material: L-isoleucinium p-toluenesulfonate monohydrate (LIPT) is synthesized and reported for the first time. The LIPT is crystallized in a non-centrosymmetric monoclinic space group P21. Structural and hydrogen bond nature of the compound is analyzed using single crystal X-ray diffraction studies. The crystal exhibits very good optical properties such as wide optical transparency in the region of 210 nm to 1100 nm and the ultraviolet wavelength emission (λ = 283 nm). The second harmonic generation efficiency is found to be 1.7 times the standard KDP. Good thermal, mechanical properties and low dielectric constant at high frequency range show that the material may be a potential candidate for optoelectronic applications.

Open access

Madiha Sarfraz, Nasar Ahmed, Khizar-ul-Haq, Shabnam Shahida and M. A. Khan

Abstract

Transition metals, such as chromium (Cr) and manganese (Mn) doped zinc oxide (ZnO) magnetic nanoparticles, were synthesized via sole gel auto-combustion method. The prepared magnetic (Zn1−(x+y)MnxCryO, where x, y = 0, 0.02, 0.075) nanoparticles were calcined in an oven at 6000 °C for 2 hours. The morphologies of the nanoparticles were investigated using different techniques. X-ray diffraction (XRD) analysis revealed that the hexagonal wurtzite structure of the synthesized nanoparticles was unaffected by doping concentration. The crystallite size measured by Scherrer formula was in the range of 32 nm to 38 nm at different doping concentrations. Nanosized particles with well-defined boundaries were observed using a field emission scanning electron microscopy (FE-SEM). Fourier transform infrared (FT-IR) spectra showed a wide absorption band around 1589 cm−1 in all the samples, corresponding to the stretching vibration of zinc and oxygen Zn–O bond. A blue shift in optical band gaps from 3.20 eV for ZnO to 3.08 eV for Zn0.85Mn0.075Cr0.075O nanoparticles was observed in diffuse reflectance spectra, which was attributed to the sp-d exchange interactions. The field-dependent magnetization M-H loops were measured using vibrating sample magnetometer (VSM). The VSM results revealed diamagnetic behavior of the ZnO nanoparticles which changed into ferromagnetic, depending on the doping concentration and particle size. The compositions of Zn, Cr, Mn and O in the prepared samples were confirmed by using the energy dispersive X-ray spectroscopy (EDX). Our results provided an interesting route to improve magnetic properties of ZnO nanoparticles, which may get significant attention for the fabrication of magnetic semiconductors.