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This work develops a microflow cytometer, based on a microfluidic chip for three-dimensional (3D) hydrodynamic focusing and a binary optical element (BOE) for shaping and homogenizing a laser beam. The microfluidic chip utilizes sheath flows to confine the sample flow along the channel centerline with a narrow cross section. In addition to hydrodynamic focusing, secondary flows are generated to strengthen the focusing in the vertical direction. In experiments, the chip was able to focus the sample flow with cross sections of 15 μm high and 8–30 μm wide at 5 m/s, under the condition of the sample flow rates between 10 and 120 μL/min. Instead of using the conventional elliptical Gaussian spot for optical detection, we used a specially designed BOE and obtained a 50 μm × 10 μm rectangular quasi-flat-top spot. The microflow cytometer combining the chip and the BOE was tested to count 3, 5, and 7 μm fluorescence microbeads, and the experimental results were comparable to or better than those derived from two commercial instruments.

Usually, optical tweezers for trapping atoms or nanoparticles are based on the focusing of a Gaussian laser beam (GB). The optical trap is characterised by its longitudinal stability (LS), expressed as the ratio of the backward axial gradient and the forward scattering forces. Replacing the GB with a LGp0 beam (one central peak surrounded by p rings) does not improve the LS because the on-axis intensity distribution is the same whatever the mode order p. However, it has been recently demonstrated that a restructured LGp0 beam can improve greatly the LS. In this paper, we consider the restructuring of a LGp0 beam when passing through a simple binary diffracting optical element called a circular π-plate (CPP). For a particular radius of the dephasing zone of the CPP, it is found that the LS is multiplied by a factor corresponding to a relative increase of about 220% to 320%.

This study presents an experimentally validated demonstration of an inverse-optimized binary phase-only gallium oxide diffractive optical element (DOE). This DOE transforms an incident Gaussian beam into a square flat-top beam at the working plane. The design methodology for this binary phase-only DOE beam shaper is founded on an efficient process that integrates the modified Gerchberg-Saxton algorithm and the adjoint method. Experimental characterization of the fabricated device on a single crystal gallium oxide substrate is conducted at a wavelength of 532 nm, confirming its ability to transform an incident Gaussian beam into a focused square flat-top beam. Such a device holds significant promise for various high-power laser applications, notably in laser welding and similar domains. Furthermore, because of the ultrawide bandgap of gallium oxide, DOEs operating at shorter wavelengths in the UV are also possible based on this technique.

The main objective in exploring a lead-free solder system comprising Gallium, Indium, and Tin lies in the desire to mitigate health hazards related to lead exposure. This research aims to substitute hazardous lead-based solder with a safer alternative due to the non-toxic nature without compromising the other properties. In this study, we investigated the partial and integral enthalpy of mixing for Gallium–Indium (Ga–In), Gallium–Tin (Ga–Sn), and Indium–Tin (In–Sn) binary alloy systems by the help of drop calorimeter at different temperatures of 673 K, 723 K, and 773 K. The results demonstrate that the enthalpy of mixing exhibits certain variations with temperature and composition, providing insights into the interatomic interactions between the constituent elements in the alloy systems. Endothermic enthalpies of mixing were obtained for the Ga–Sn and Ga–In system but slightly exothermic nature was observed for In–Sn system. After getting enthalpy data from the experiments, a Redlich–Kister polynomial fitting was employed to accurately describe the binary interactions within each alloy system. The variation of enthalpy of mixing was found to be temperature dependent for the Ga–In and Ga–Sn system but temperature independency was observed in In–Sn system. Binary interaction parameters for the Ga–Sn, Ga–In and In–Sn were determined at different temperatures. It was observed that interaction parameters are temperature dependent for the Ga–In and Ga–Sn system and independent for the In–Sn system. Comparison of partial molar and integral molar enthalpies of mixing obtained from this study with the literature was attempted. It was found that the results obtained in this study show very good agreement with the data available in literature.

SrY 2 O 4 belongs to the family of AB 2 O 4 (A = alkaline earth metal, B = rare earth element) type spinel oxides. SrY 2 O 4 is an inter oxide in SrO and Y 2 O 3 pseudo-binary phase diagram. It has attracted immense interest as a promising host lattice owing to its thermal and chemical stability. The luminescent characteristics of SrY 2 O 4 phosphors make them promising candidates for field emission displays. In the present review article, recent progress in the synthesis and luminescent properties of bare and doped SrY 2 O 4 phosphors are reviewed. In the first part, different synthesis routes and their resultant outcomes are discussed. Then, the downconversion and upconversion luminescent characteristics of undoped and doped SrY 2 O 4 phosphors are reviewed. The effect of site occupancy, morphology, reaction conditions, different excitation wavelengths, dopant concentrations, and energy transfer mechanisms are explained in detail. In the end, challenges and future scope in luminescence and synthesis of SrY 2 O 4 are proposed. This review article gives a complete summary for the drawbacks and current challenging issues of SrY 2 O 4 phosphors, which can give potential sprout for future work.

β-Gallium oxide is a wide bandgap material that is used in many electronic devices owing to its ultra wide bandgap of ~ 5 eV. It is commonly doped with rare earth metals like europium to improve its electronic and photoluminescence properties. However, the effect of doping concentration on particularly the optical properties has not been clearly reported yet. Here the aim was to dope β gallium oxide with different concentrations of europium. Therefore europium and gallium oxide were co-sputtered to get varying concentrations of europium in β gallium oxide structure. The doping concentration varied from 4.6 to 10.1 mole% of europium. Their microstructure and phase was studied by SEM and XRD, respectively and their optical performance was studied using UV–Vis spectrophotometer. The optical bandgap of β gallium oxide was found to decrease due to doping with europium. Although the transmittance increased drastically with increase in doping concentration from 4.6 to 10.1%, their bandgap was independent of the dopant concentration. In consultation with the binary phase diagram and photoluminescence of the thin films, the optimal dopant concentration in β gallium oxide was found to be around 10% Eu.

The optical properties of silver and gold based bimetallic alloys make possible to adjust their plasma frequency. The direct alloying and plasmonic activity of thin layers from the Au-Sb system are presented in the present work. The thin films were deposited by thermal co-evaporation of gold and antinomy. The chemical and phase composition of thin films, were analysed by X-ray microanalysis and X-ray diffraction (XRD), respectively. The results of the X-ray microanalysis show that the composition of the thin layers corresponds well to the predetermined. The XRD patterns, depending on the envisaged compositions, show formation of intermetallic compound AuSb 2 and binary alloys between the initial elements and the intermediate compound, which is in accordance with the Au-Sb phase diagram. The dispersion of the complex permittivity was determined by spectroscopic ellipsometry. The results show that the increase of the antimony content leads to an increase of the values of the imaginary part of the complex permittivity in the visible spectral region at photon energies greater than 3 eV, and a decrease in the ultraviolet spectral region. Based on the obtained dispersions of the complex permittivity, extinction cross-sections and local field enhancement of spherical Au-Sb nanoparticles were determined and their plasmon activity was evaluated.

Rapidly solidified (RS) binary Sn–5 wt .% Sb and ternary Sn–5 wt .% Sb– x wt .% Ag, x  = 1, 3 and 5 solder alloys were prepared in form of ribbons using melt spinning technique (MS). X-ray diffractometer (XRD), scanning electron microscopy (SEM) attached with energy dispersive x-ray technique (EDX) and differential scanning calorimetry (DSC) were used to investigate the impacts of Ag contents on microstructures and properties of the binary Sn–5 wt .% Sb rapidly solidified alloy. XRD analysis confirmed the formation of an ultrafine microstructure of Ag 3 Sn intermetallic compound in addition to a supersaturated solid solution of Sn by Sb and Ag. Moreover, SEM and EDX analysis assigned the formation of SnSb intermetallic compound as well as the dissolution of Sb and Ag in β -Sn with maximum wt .% of 20.75 and 11.7 for Sn-5Sb and Sn-5Sb-5Ag ribbons, respectively. The melting point of the melt spun ribbons was lowered by 3.7 °C, 1.7 °C, 5.4 °C and 2.3 °C for the 0, 1, 3 and 5 Ag containing solder alloys as deduced by DSC. The rapidly solidified ribbons exhibit better Vickers hardness due to the microstructure refinements and the extension of solid solubilities of the alloying elements.

The solid-phase reaction method for preparing forsterite (Mg2SiO4) using the MgO and SiO2 powders has the disadvantages of high reaction temperature, long reaction time, and inhomogeneous reaction depending on the particle size of MgO. Therefore, MgO-based powders with a high reactivity were synthesized using a coprecipitation method with substitutional elements (Mn or Ni), and the effects of processing parameters on synthesizing MgO-based binary composition powders were investigated through the particle characteristics. The crystal structure was changed continuously with the contents and species of substitutional elements, showing the same trend as the atomistic simulation results. The MgO-based powders showed a higher reactivity than the conventional MgO powder, which could be confirmed in the particle characteristics, such as particle size and crystallinity, obtained in a short reaction time and at a relatively low temperature. The optimum composition ratio in the binary composition powder for forming the Mg2SiO4 depended on the type of substitutional element, and the reaction mechanism was identified based on the particle characteristics.