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In recent years, redox additive electrolytes have been anticipated as effectual selections over modest aqueous electrolytes. In the present study, porous carbon derived from nonporous Saccharum spontaneum confirms its efficacy as a supercapacitor electrode, in the presence of an optimized redox active electrolyte. Carbon synthesized via ZnCl2 activation at 600 °C shows optimum performance in terms of surface area (1590 m2 g−1) and porous properties. The same is reflected in the sample for excellent energy storage performance. High capacitances of 561 F g−1 and 275 F g−1 were obtained in an aqueous 1 M H2SO4 electrolyte, for three-electrode and two-electrode configurations, respectively. Similarly, with the incorporation of 0.01 M hydroquinone (HQ), as a redox additive to the 1 M H2SO4 electrolyte, a high specific capacity was achieved for three-electrode (1392 C g−1) and two-electrode (658 C g−1) configurations. Remarkably, a good cyclic stability of 77% retention after 5000 cycles has been evidenced in a HQ-incorporated aqueous electrolyte. A similar trend is followed for energy density, power density and other relevant electrochemical properties, as well.

Swift heavy ion (SHI) irradiation in thin films significantly modifies the structure and related properties in a controlled manner. In the present study, the 120 MeV Ag ion irradiation on AgInSe2 nanoparticle thin films prepared by the thermal evaporation method and the induced modifications in the structure and other properties are being discussed. The ion irradiation led to the suppression of GIXRD and Raman peaks with increasing ion fluence, which indicated amorphization of the AgInSe2 structure along the path of 120 MeV Ag ions. The Poisson's fitting of the ion fluence dependence of the normalized area under the GIXRD peak of AgInSe2 gave the radius of the ion track as 5.8 nm. Microstructural analysis using FESEM revealed a broad bi-modal distribution of particles with mean particle sizes of 67.5 nm and 159 nm in the pristine film. The ion irradiation led to the development of uniform particles on the film surface with a mean size of 36 nm at high ion fluences. The composition of the film was checked by the energy dispersive X-ray fluorescence (EDXRF) spectrometer. The UV-visible spectroscopy revealed the increase of the electronic bandgap of AgInSe2 films with an increase in ion fluence due to quantum confinement. The Hall measurement and EDXRF studies showed that the unirradiated and irradiated AgInSe2 films have n-type conductivity and vary with the ion fluence. The changes in the films were tuned with different ion fluence and are favorable for both optical and electronic applications.

Context: Original research. Aims: The aim of the present study to evaluate the effects of prosthetic material on the stress distribution of implant-supported prosthesis in the bone around implants using finite element analysis and to draw a comparison so as to which material causes the least amount of stress on the bone. Settings and Design: In vitro finite element analysis - Comparative study. Methods and Materials: Models of the implants and the mandible were constructed using SOLID WORKS software and then they were transferred to another software ANSYS Work bench for FEA. A four-unit prosthesis was designed in the region of anterior mandible with implants being placed in 32 and 42 regions. The prosthesis was made of different materials in different models, M1 was of made of cobalt chromium framework, M2 was made of Titanium framework, M3 was made of zirconia framework each with layered ceramic. M4 was a monolithic zirconia prosthesis. The values of the Von Mises stresses generated in the implant, superstructure and alveolar bone around were calculated. The total deformation and stress generated in different models were calculated and compared. Statistical analysis used: Von mises Stress Analysis, Unpaired t test. Results: Zirconia and Monolithic zirconia showed comparatively less total deformation and stress levels in peri-implant bone. Titanium prosthesis caused less total deformation and stress distribution as compared to cobalt chromium. Conclusions: The distribution of stress in peri implant bone is evidently dependent on the prosthesis material and different materials cause different amount of deformations as they differ in their clinical properties.

In the present study, the thermoluminescence (TL) properties of an Eu3+ -doped CaNa2 (SO4 )2 phosphor were studied. The Eu3+ -doped CaNa2 (SO4 )2 phosphor was synthesized using the combustion method. The samples were well crystallized in the monoclinic phase. The TL glow curve of the Eu3+ -doped CaNa2 (SO4 )2 phosphor showed a single prominent peak at around 210°C with showed linearity on increasing exposure. The response curve of the synthesized phosphor showed linearity in the range 500-7000 Gy. Trapping parameters of synthesized phosphors such as activation energy, frequency factor, and order of kinetics were calculated in the study. These trapping parameters were determined by different methods such as Chen's peak method, the initial rise method, and Ilich's method. Each characteristic of these outcomes demonstrated that the synthesized Eu3+ -doped CaNa2 (SO4 )2 phosphor had outstanding TL properties and might be valuable for TL dosimetry application.

In this report, we discuss the structural and dielectric properties of TM0.7Zn0.3Fe2O4 (TM = Ni, Mn) spinel ferrites. The ferrite materials under study were synthesized by the solid state reaction method. For structural elucidation, these materials were characterized by X-ray diffraction technique and Raman scattering Method. The analysis of XRD data obtained in the angular range of 10° – 80° revealed that both the samples under study have crystallized in cubic structure (Fd3m). The XRD results were verified by Raman spectral study from the display of fingerprint modes of vibration related to cubic structure acquired by these ferrite materials. The dielectric study infers the samples are extremely good dielectric materials with high dielectric constant and comparatively low loss value. The dielectric constant of Zn doped of MnFe2O4 is higher. However, the resonance like behaviour is observed for Zn doped NiFe2O4. The high dielectric constant and relatively low loss value infer their feasibility in advanced electronic device applications.

We report a change in the red photoluminescence of the Eu3+ doped Na2Sr2Al2PO4Cl9 phosphor via doping of singly, doubly and triply ionized ions. The synthesized phosphors show good crystalline nature. The EDS analysis confirms the presence of desired elements in the phosphor samples. The vibrational feature of the phosphor was confirmed by FTIR analysis. The photoluminescence excitation spectra of the phosphor show three peaks at 317, 395 and 467 nm. The Eu3+ doped Na2Sr2Al2PO4Cl9 phosphor emits intense red color on excitations with 395 and 467 nm wavelengths. However, the photoluminescence intensity of the phosphor is larger for 395 nm excitation. When the singly, doubly and triply ionized ions are co-doped in the Eu3+ doped Na2Sr2Al2PO4Cl9 phosphor (i.e. F−, WO42−, MoO42−, VO43−, La3+, and Y3+) the photoluminescence intensity of the phosphor is decreased significantly. The decrease in photoluminescence intensity is due to change in local crystal structure created by these ions. Interestingly, the photoluminescence intensity of phosphor increases many times when the (Y3+) ion incorporated phosphor is excited with 317 nm wavelength. The CIE diagram shows color emitted in the red region of visible spectrum and the color purity is larger for triply ionized (Y3+) ion. Thus, the singly, doubly and triply ionized ions activated Na2Sr2Al2PO4Cl9: Eu3+ phosphor may be used in displays devices, photonic devices, solid state lighting and white LEDs.

We report here thermoluminescence properties of Eu3+ doped Na2Sr2Al2PO4Cl9 phosphor via doping of singly, doubly and triply ionized ions on the basis of PL studies done for this sample. The proposed sample was synthesized using solid state reaction method. Vibrational feature of this phosphor was confirmed by FT-IR spectra. This sample shows high degrees of crystallinity. All subseries are irradiated with 60Co- γ (gamma) source and thermoluminescence studies were done for all subseries formed by doping of singly, doubly and triply ionized ions. The result shows that all the series give highest TL intensity at low dose rate. On doping of triply doped ionized ion (Y3+), TL intensity is enhanced to some extent. Deconvolution of broad TL glow data formed for some sample were done by using TLAnal computerized software. Thermoluminescence studies of these Eu3+ doped SrYAl3O7 phosphor were done by Nucleonix TL 1009I thermoluminescence (TL) reader. Trapping parameters of each phosphor such as activation energy (E), order of kinetics (b) and frequency factor (s) were calculated by Chen's peak shape method, Initial rise method and Ilich method. Thus, the singly, doubly and triply ionized ions co-doped with Na2Sr2Al2PO4Cl9: Eu3+phosphor may be used in high dose thermoluminescence dosimetric application in various fields.

The laser irradiation with band gap light of thermally evaporated As40Se55Bi5 and As40Se45Bi15 thin films was found to be accompanied by structural changes which in turn changed the optical constan...

This review focuses on various aluminium alloys as matrix materials used for synthesis of in-situ metal matrix composites(MMCs) with different reinforcements like graphite, Al 2 O 3 , SiC, TiB 2 and so on for their excellent characteristic properties. Taking their limitations into account, tailoring the physical, mechanical as well as wear properties of these composites with the use of appropriate type and amount of reinforcement along with optimum process parameters has also been investigated for different applications as a substitute of conventional metals and alloys. A numerous research activities on aluminium and aluminium alloy based MMCs have been and being carried out and review of some of them has been mentioned in this paper to compare different reinforcements and various techniques involved in synthesis of MMCs with special reference to stir casting route.

The interface of Ni-NiO thin films was developed by thermal evaporation of nickel and subsequent annealing in oxygen atmosphere at 400 °C at varying duration of time. The evolution of layer thicknesses with annealing time was studied using rutherford backscattering spectrometry. The structural characterization showed grain growth stagnation for Ni at higher duration of annealing. The Ni phase had more crystallinity compared to the NiO phase. The surface was studied using atomic force microscope. The magnetic domains were also imaged. Magnetic stripe domain patterns were observed for selected films. Variation in saturation magnetisation and coercivity with annealing time was observed. The observation of weak exchange bias shows the importance of antiferromagnetic phase in determining the exchange bias properties. Thermal annealing of Ni films caused a competition among oxidation and grain growth.

Evolution of the structure and surface morphology of thin films composed of two selenium based chalcogenide phases, AgInSe2 and Ag2Se on 140 MeV ion irradiation is reported. At this high energy, the projectile Ni ions sputtered the surface of the films through energy deposition to the target electrons. The sputtering led to decrease of silver and selenium concentration, but did not affect indium concentration. Surface analysis by field emission scanning electron microscopy study revealed nanoparticles of widely varying shapes and sizes on the surface of the films. Irradiation did not affect the particle size distribution which peaked at ~100 nm. The two phases, AgInSe2 and Ag2Se exhibited different sensitivity to 140 MeV Ni ion irradiations. While Ag2Se phase was insensitive, the AgInSe2 phase showed complex structural modifications at intermediate fluences, finally getting amorphized at high ion fluences. Analysis of the fluence dependence of Grazing Incidence X-ray Diffraction (GIXRD) peak area of AgInSe2 phase indicated that each ion that penetrated the film, created an amorphous column of 1.6 nm radius. Surrounding the amorphous column, a cylindrical crystalline AgInSe2 region of radius 8.2 nm, but with reduced lattice parameters formed. High resolution transmission electron microscopy image also confirmed registration of amorphized tracks and the modified crystalline region of similar radii around the path of 140 MeV Ni ions in a grain of AgInSe2 as obtained from GIXRD study.

The structural, microstructural and electronic band gap properties of bilayer Bi/As2Se3 thin films prepared on glass substrate have been discussed in detail. The thin films prepared by thermal evaporation technique under high vacuum were characterized by X-ray diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FESEM) and UV–visible–NIR spectrophotometer. The bilayer films with small Bi thickness showed amorphous nature, while large Bi thickness film led to the development of sharp XRD peaks corresponding to Bi and Bi2Se3 phase. The band gap of the studied film decreased with increasing Bi layer thickness which is explained on the basis of high concentration of localized defect states in the band gap region. The FESEM images showed the smooth and homogeneous surface for all the films. The Raman spectra showed the different structural units like AsSe3 pyramidal unit and Se8 rings that change with the Bi layer thickness. The present study reveals the interface diffusion of Bi into As2Se3 layer and interaction of Bi with Se due to exposure of the films to UV radiation.

In the present study, Bi/As2Se3 bilayer thin films (100 nm Bi as top layer and 800 nm As2Se3 as bottom layer) were prepared by thermal evaporation technique and were annealed at 165 °C for ½ h, 1 h and 2 h. The structural, micro-structural and optical studies of the films were characterized by X-ray diffractometer (XRD), Field emission scanning electron microscopy (FESEM), Atomic force microscopy (AFM) and Fourier transform infrared (FTIR) Spectrophotometer. The XRD study revealed the annealing induced diffusion of Bi into As2Se3 layer and its reaction with Se leading to the formation of Bi3Se2 phase. The as deposited Bi/As2Se3 bilayer film exhibited strain at the interface leading to localized states in the band gap of the bottom As2Se3 layer with a consequent reduction of its band gap. The increase in annealing time from 1/2 h–2 h led to strain relaxation and increased the band gap towards that of the pristine As2Se3 along with the precipitation of a second Bi3Se2 phase. The increase in optical band gap has been explained by the density of localized states in the gap. The change in refractive index, transmission, absorption coefficient, dielectric constant is the consequence of annealing effect. The FESEM images revealed the smooth surface for as deposited bilayer film and a large number of agglomerated grains of As2Se3 have been seen in the annealed films. The AFM study showed the grain growth stagnation or even decrease of grain size on prolonged annealing.

Aligned ZnO nanorods (NRs) were synthesized by a simple and inexpensive hydrothermal method. Morphological, structural, photoabsorbance and photoluminescence studies have been carried out using field emission scanning electron microscopy (FE-SEM), grazing incidence X-ray diffraction (GIXRD), Raman, UV–visible and Photoluminescence spectroscopy. Results show that crystallinity and alignment of ZnO NRs lead to good photocatalytic activity in the presence of visible light. The Photoluminescence spectra revealed a decrease in the UV emission, suggesting a reduced recombination of the photo generated carriers. The visible region emission is due to the surface oxygen vacancies. Increase of charge separation rate observed from emission spectra and the vacancy related sub-bands in the absorbance spectra are together responsible for the enhanced visible light photocatalytic activity of ZnO NRs. Vertically aligned 1-D morphology of ZnO NRs and the presence of oxygen vacancy states assist in the visible light photocatalytic degradation of Methylene Blue dye.

A series of Cu-C o ferrite based bulk particles (Cu (1-x) Co(x)Fe2O4) in which x is varied from 0.0 to 0.6 were prepared by Solid State reaction route. The influence of the Co content on the structural properties of cubic Nickel ferrites (CuFe2O4) was investigated using Raman spectroscopy. Slight reduction in the lattice parameter of Co doped CuFe2O4 has been observed as compared to the parent CuFe2O4. From Raman scattering spectra, a shoulder like feature has been observed in both parent and doped com pounds which reveals that octahedral site is occupied by Co, Cu and Fe ions and tetrahedral site is occupied by only Feion.

The effect of Ni doping in BiFe1−xNixO3 (BFNO) multiferroics are studied by X-ray diffraction (XRD), Fourier transmission infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), hysteresis loop (M–H), temperature dependent magnetization (FC-ZFC) measurements and electron spin resonance (ESR) techniques. The XRD and FTIR studies indicate that the BFNO compounds remain in rhombohedral (R3c) phase without appearance of any structural transformation due to Ni doping. The XPS studies show the oxidation states of Fe ions as 3+, whereas Bi is found to be in a mixed valence state of 2+ and 3+ in BFNO. The Ni ion doping enhances the saturation magnetization from 0.179 emu/g (x = 0.025) to 2.38 emu/g (x = 0.20), which is higher than the reported values found in literature. The FC-ZFC magnetization studies suggest the presence of a magnetic phase transition from a weak ferromagnetic to a spin glass state at low temperature. The ESR studies confirm the ferromagnetic state of BFNO samples.

Present study investigates the structural and magnetic properties of TiO2 thin films prepared by electron beam evaporation technique, annealed at 900 °C and irradiated with 500 keV Ar2+ ions. The films before irradiation exhibit anatase phase. Irradiation leads to diffused XRD peaks indicating amorphisation of the anatase phase at the fluence of 1 × 1014 ions/cm2. Increasing the fluence to 5 × 1016 ions/cm2 leads to evolution of brookite phase out of the amorphous TiO2. In addition, an impurity phase, Ti4O7 is observed in pristine as well as in irradiated films, which show radiation resistant behavior to 500 keV Ar2+ ion irradiation upto the highest fluence 5 × 1016 ions/cm2. Anatase to brookite phase transformation followed by an intermediate amorphous phase occurs without showing either grain growth or change in film thickness as evidenced from Atomic Force Microscopy (AFM) and Rutherford’s Back Scattering (RBS) measurements, respectively. Further, both pristine and irradiated films exhibit ferromagnetic behavior at room temperature (RT) irrespective of their phase and crystallinity. The difference in magnetization observed in pristine and film irradiated at ion fluence 5 × 1016 ions/cm2 is ascribed to the difference in oxygen vacancies.

In the present study, the AgInSe2 (AIS) thin films 500 nm in thickness were prepared by selenization of the Ag/In/Ag/In multilayer deposited by DC magnetron sputtering. The selenization was carried out at 250 °C and was followed by annealing at 450 °C, 475 °C and 500 °C. The selenized and annealed films were characterized by grazing incidence X-ray diffraction (GIXRD), UV-Visible-NIR spectroscopy, Field-Emission Scanning Electron Microscopy (FESEM) and Raman spectroscopy. The XRD analysis revealed the formation of the desired AgInSe2 phase along with Ag2Se (AS) impurity phase. The impurity Ag2Se phase is being diminished at higher annealing temperature (500 °C) resulting the formation of AgInSe2 phase. The super ionic nature of α-Ag2Se phase facilities the diffusion of Ag ion with its neighbouring tetrahedral sites. The low band gap Ag2Se impurity phase suppression by annealing at 500 °C lead to optical band gap increase. The Raman spectrum shows individual AgInSe2 and Ag2Se peaks and also the overlapping of these two phases. The Ag2Se peaks are vanished after annealing. The EDXRF study revealed that the film is off-stoichiometric and exhibit n-type conductivity. The RBS analysis indicates the diffusion of the film material to the glass substrate. From Hall measurement it is confirmed that the film shows n-type conductivity and the resistivity decreases with increasing the annealing temperature.

In the present report, we have studied the structural and optical change in the In2Se3 thin films prepared by the thermal evaporation method, deposited on a glass substrate and annealed at 250°C. B...

Towards enhancing the thermal performance and fuel flexibility of existing domestic cooking stoves, the present work employs the heat recirculation mechanism of the porous medium (PM) combustion to these burners offering greater fuel compatibility for both liquefied petroleum gas (LPG) and renewable fuel dimethyl ether (DME). To establish the advantages of DME combustion than that of LPG within the stove, experimental measurements and numerical modeling are performed in a two-layer PM burner. The numerical model is used to investigate the dynamics of DME flame in the PM through reaction path analyses. Both experiment measurements and numerical predictions show lower CO emissions for DME flame than that of LPG flame inside the PM stove. With the use of DME instead of LPG, following the guideline of World Health Organization, the maximum allowable equivalence ratio can be extended from 0.4 to 0.5 and the thermal load from 4.0 kW to 5.0 kW. Moreover, the total heat generation rate, the gas- and solid-phase temperatures and radiant efficiencies of the burner with DME flame are higher than that with LPG flame at the same input conditions. However, the stability ranges of DME flame are found to be less than that of LPG flame.

In our earlier report, where we have demonstrated ferromagnetic behavior at room temperature (RT) in TiO2 thin films deposited through electron beam evaporation technique followed by annealing either in Ar or O2 atmosphere [Mohanty et al., Journal of Magnetism and Magnetic Materials 355 (2014) 240–245], here we have studied the evolution of structure and magnetic properties after irradiating the TiO2 thin films with 500 keV Ar2+ ions. The pristine film while exhibits anatase phase, the films become amorphous after irradiating at fluence in the range 1 × 1014 to 1 × 1016 ions/cm2. Increasing the fluence up to 5 × 1016 ions/cm2, amorphous to crystalline phase transformation occurs and the structure becomes brookite. Although anatase to rutile phase transformation is usually reported in literatures, anatase to brookite phase transformation is an unusual feature which we have reported here for the first time. Such anatase to brookite phase transformation is accompanied with grain growth without showing any change in film thickness evidenced from Rutherford’s Back Scattering (RBS) measurement. From scanning probe micrographs (SPM), roughness is found to be more in amorphous films than in the crystalline ones. Anatase to brookite phase transformation could be realized by considering the importance of intermediate amorphous phase. Because due to amorphous phase, heat deposited by energetic ions are localized as dissipation of heat is less and as a result, the localized region crystallizes in brookite phase followed by grain growth as observed in highest fluence. Further, we have demonstrated ferromagnetic behavior at RT in irradiated films similar to pristine one, irrespective of their phase and crystallinity. Origin for room temperature ferromagnetism (RTFM) is attributed to the presence of oxygen vacancies which is confirmed by carrying out XPS measurement.

This article reports a study on simultaneous estimation of four parameters for combined-mode conduction and radiation heat transfer in a 2D rectangular porous matrix with a localized volumetric hea...

Simultaneous estimation of the gas velocity, scattering albedo, and downstream pore diameter in a two-layer planar porous matrix involving combined mode conduction, convection, and radiation heat transfer with combustion is reported. Non-local thermal equilibrium between the gas and the solid phase is accounted by separate energy equations for the two phases. Performances of the genetic algorithm, genetic algorithm parallel, simulated annealing, multiple starting point algorithm parallel, pattern search algorithm, pattern search algorithm parallel, and global search algorithm in the simultaneous estimation of three parameters are analyzed. All the algorithms utilize a priori knowledge of the axial gas temperature distribution, and the magnitudes of the convective and the radiative heat fluxes at the outer surface of the porous matrix. With volumetric radiative information needed in the solid phase energy equation computed using the discrete transfer method, the two energy equations are simultaneou...

Many different methods, such as screen printing, gravure, flexography, inkjet etc., have been employed to print electronic devices. Depending on the type and performance of the devices, processing is done at low or high temperature using precursor- or particle-based inks. As a result of the processing details, devices can be fabricated on flexible or non-flexible substrates, depending on their temperature stability. Furthermore, in order to reduce the operating voltage, printed devices rely on high-capacitance electrolytes rather than on dielectrics. The printing resolution and speed are two of the major challenging parameters for printed electronics. High-resolution printing produces small-size printed devices and high-integration densities with minimum materials consumption. However, most printing methods have resolutions between 20 and 50 μm. Printing resolutions close to 1 μm have also been achieved with optimized process conditions and better printing technology.

Ni1−xZnxO/Ni nanocomposite samples synthesized by wet chemical method were characterized by X-ray powder diffraction, Fourier Transform Infrared (FTIR) spectrometer, UV–Vis spectrometer and Nine Tesla Physical Property Measurement System (PPMS)-based vibrating sample magnetometer (VSM). XRD spectra contained peaks due to NiO and Ni. Rietveld refinement of XRD data indicated the change in lattice parameter is more than twice in NiO than in Ni suggests that Zn goes more favorably into NiO than in Ni. The band gap of NiO in Ni1−xZnxO/Ni samples increased from 3.58 to 3.81 eV with increasing x from 0 to 0.07 and thereafter the band gap slightly decreases. NiO/Ni nanocomposites show strong room temperature ferromagnetism. The ferromagnetic interaction further enhanced with 1% of Zn doping into NiO in NiO/Ni nanocomposite. Beyond this doping concentration, the magnetic interaction does not show any systematic variation. The observation of room temperature ferromagnetism in nanocomposite samples is explained by combining the effect of bound magnetic polaron and the magnetization of system with the distribution of magnetic ions as meagerly dispersed in large clusters. Our study indicated that Ni0.99Zn0.01O/Ni nanocomposite sample could be useful for magnetic recording device application.

A series of KAl(SO4)2 phosphors with different Eu3+ doping concentrations have been synthesized by solid-state reaction method. In the present work, the properties of synthesized Eu3+ doped KAl(SO4)2 phosphors have been examined by XRD, Photoluminescence (PL), and photometric characterization techniques. Under Near Ultraviolet (NUV) and blue excitation at 395nm and 466nm, PL emission spectra observed at 593nm and 614nm, which are ascribed due to 5D0→7F1 and 5D0→7F2 transition of Eu3+ ions. The emission band of 614 nm indicates the highest emission intensity compared to the 593 nm emission band. The PL emission spectra depict maximum intensity at 0.7mol% doping of Eu3+ ions. In addition, the synthesized Eu3+ activated KAl(SO4)2 phosphors show good color chromaticity coordinates, which is lies in the orange-red region. All these results indicated that the synthesized Eu3+ activated KAl(SO4)2 phosphors have potential results for future work in the field of solid state lighting.

With progressing miniaturization of modern electronic devices, interconnects become increasingly smaller. Additionally, as electronic devices move away from rigid substrates toward flexible ones, understanding their mechanical and structural stability is becoming crucial. In this work, a thorough mechanical characterization of copper thin films deposited on flexible substrates was performed with two techniques, namely well-established synchrotron X-ray diffraction (sXRD) and the rather new usage of reflectance anisotropy spectroscopy (RAS) for mechanical characterization of thin films. The comparison of these two techniques shows that RAS can be reliably used for the accurate and prompt yield stress measurements. The acquisition time of RAS is much faster than that of sXRD: 1 second per data point compared to several seconds per data point for sXRD experiments. Moreover, the signal-to-noise ratio of the RAS data is much higher than that of the sXRD. Our results show that yield stress of Cu films increases with the decrease in the film thickness, going from 352 MPa for a 500 nm films to 793 MPa for a 50 nm thick film. Microstructure analyses of the films by electron microscopy allowed correlation of the mechanical behavior of the films to their grain morphologies. We have shown that RAS can supplement sXRD measurements due to a faster acquisition rate which allowed us to analyze the creep behavior of our copper thin film at different strain rates.

Present study investigates the photoabsorption properties of single crystal rutile TiO2 (110) surfaces after they have been implanted with low fluences of cobalt ions. The surfaces, after implantation, demonstrate fabrication of nanostructures and anisotropic nano-ripple patterns. Creation of oxygen vacancies (Ti3+ states), development of cobalt nano-clusters as well as band gap modifications have also been observed. Results presented here demonstrate that fabrication of self organized nanostructures, upon implantation, along with the development of oxygen vacancies and ligand field transitions of cobalt ion promote the enhancement of photo-absorbance in both UV (∼2 times) and visible (∼5 times) regimes. These investigations on nanostructured TiO2 surfaces can be important for photo-catalysis.

Application of the lattice Boltzmann method (LBM) in solving a combined mode conduction, convection, and radiation heat transfer problem in a porous medium is extended. Consideration is given to a 1-D planar porous medium with a localized volumetric heat generation zone. Three particle distribution functions, one each for the solid temperature, the gas temperature, and the intensity of radiation, are simultaneously used to solve the gas- and the solid-phase energy equations. The volumetric radiation source term appears in the solid-phase energy equation, and it is also computed using the LBM. To check the accuracy of the LBM results, the same problem is also solved using the finite volume method (FVM). Effects of convective coupling, flow enthalpy, solid-phase conductivity, scattering albedo porosity, and emissivity on axial temperature distribution are studied and compared with the FVM results. Effects of flow enthalpy, solid-phase conductivity, and emissivity are also studied on radiative output...

Rare earth activated fluoride phosphors have attention in recent years in the field of solid state lighting. In the present study, RE (RE = Ce3+,Eu2+) doped/co-doped BaSiF6 phosphor has been synthesized by low temperature solution combustion method at 500 ± 20 °C using urea as a fuel. Photoluminescence (PL) properties of this sample were investigated by RF-5301 PC Spectrofluorophotometer. The structural, vibrational features and morphology of all the samples were analyzed by X-ray Diffraction (XRD), and Fourier Transform-Infrared Spectroscopy (FT- IR) which showed that the samples were crystallized in a well known structure. Photoluminescence characterization of Eu2+ doped phosphor shows a blue emission at λmax ~460 nm under the excitation of 287 nm. The photoluminescence properties of the as‐prepared phosphors were investigated and the Ce3+ ions in these hosts were found to give little broadband emission in the UV range at 344 nm on exciting it at 300 nm. A broad PL excitation peak is obtained on co-doping Ce3+ with Eu2+ in the range of 300–425 nm highest intensity at 362 nm gives broad blue emission at 440 nm. This luminescent powder are expected to find out potential applications in the blue emitting phosphor converted white light emitting diodes and optical display systems.

The development of blue LEDs [1] enabled one to construct white LEDs by combining them with appropriate phosphors. Recently Mn4+-doped fluorides have been put into commercial use as the red phosphors for high color-rendering white LEDs [2]. However, in order to suppress the degradation due to high humidity and high temperature, a special surface treatment is required for these phosphors. Therefore, the search of other red phosphors activated by Mn4+ is still desired. For theoretical design of novel phosphors, non-empirical prediction of optical parameters such as the crystal-field and Racah parameters is quite important. The purpose of this study is to establish a first-principles approach to predict these parameters of transition metal ions in crystals. In this work, the crystal-field and Racah parameters of ruby (Cr3+ doped α-Al2O3) were evaluated based on the first-principles calculations using the relationship between the ligand-field theory and the molecular orbital (MO) theory derived by Sambe and Felton [3]. Two types of first-principles methods were adopted. One is the discrete-variational (DV)-Xα method [4], which is an MO calculation method based on the one-electron approximation. The other is the discrete variational multi-electron (DVME) method [5], which is a configuration-interaction (CI) calculation method based on the explicit many-electron wave functions. The estimation of the crystal-field and Racah parameters were performed in the following three approaches. (1) Estimation based only on the DV-Xα method (2) Estimation based only on the DVME method (3) Estimation based on the combination of the DVME method and the DV-Xα method The results show that the values of the crystal-field and Racah parameters obtained by the approach (3) are in the best agreement with the values obtained by fitting to the experimental data [6], indicating that CI calculations using some corrections based on the one-electron MO calculations are effective for the non-empirical estimation of the crystal-field and Racah parameters [7]. These results also provide theoretical basis for the configuration-dependent correction and the correlation correction introduced in our previous CI calculations of ruby [5]. This approach could be applied to prediction of d-d transitions of Mn4+ in crystals to find a suitable host for novel Mn4+-activated red phosphors for white LEDs. [1] I. Akasaki and H. Amano, Jpn. J. Appl. Phys. 45, 9001 (2006). [2] J. E. Murphy, F. Garcia-Santamaria, A. A. Setlur, and S. Sista, SID 2015 DIGEST, 927 (2015). [3] H. Sambe and R. Felton, Int. J. Quant. Chem., 10, 155 (1976). [4] H. Adachi, M. Tsukada, and C. Satoko, J. Phys. Soc. Jpn. 45, 875 (1978). [5] K. Ogasawara T. Ishii, I. Tanaka, and H. Adachi, Phys. Rev. B 61, 143 (2000). [6] W. M. Fairbank, Jr., G. K. Klauminzer, and A. L. Schawlow, Phys. Rev. B 11, 60 (1975). [7] K. Ogasawara, K.C. Mishra, and J. Collins, ECS J. Solid State Sci. Technol. 9, 016011 (2020).

Energy transfer between donor and acceptor ions is an important phenomenon in phosphor applications. In a quantum electrodynamic formulation of the energy transfer process, the donor-acceptor interaction is mediated by photons. In the presence of a metal, however, donor-acceptor interactions may also be mediated by surface plasmons. For donor-acceptor pairs near a smooth planar metallic surface, the probability of surface plasmon-mediated transfer has been estimated, and depends on both the donor-acceptor distance and the distance of each ion from the metallic surface. With the goal of designing an experiment to directly observe surface plasmon-mediated energy transfer, we simulated plasmon-mediated energy transfer in a solid using Monte Carlo methods. Using MatLab, we constructed a solid doped with randomly placed acceptors and donors, simulated the energy transfer process, and plotted the donor decay curves. We show that the plasmon-mediated transfer rate can be comparable to the radiative decay rate, and that the shape of the donor decay curves in plasmon-mediated transfer differs greatly from those resulting from Foerster-Dexter energy transfer. Thus, for a well-designed experiment, it should be possible to unambiguously identify the role of surface plasmons in the energy transfer process.

In order to improve the performance of phosphors in lighting and display devices, one needs to understand the temperature dependence of the radiative and nonradiative processes of optical ions in solids. In this presentation, we have revisited the theory of radiative transitions from an excited state of a polyatomic system within the framework of the proper adiabatic theory. First the transition rate for spontaneous emission from an excited state to the ground state has been derived rigorously using the methods of molecular quantum electrodynamics. It is assumed that this transition is associated with a loss of energy through the creation of p phonons in the system. It will be shown for the first time in a rigorous manner that only limited number of vibrational modes for which the Huang-Rhys parameter, s, is nonzero will participate. These modes will be identified as the active modes. Other modes will be completely passive during the relaxation process. It is speculated that these active modes are the local vibrational modes, and can be identified from the vibronic spectra of rare earth ions, particularly at low temperature. Based on the present formulation of the problem, the band shape function, W(p,T), will be derived. This band shape function will be used to interpret available vibronic spectra for some optical ions at low temperature.

Ion beams of widely varying energies from keV to GeV have played a significant role in the modification of materials. The manuscript reports the influence of 120 MeV Ag swift heavy ion irradiation (SHI) at two different fluence on As40Se58Bi02 and As40Se45Bi15 thin films. The irradiation has shown strong impact on the optical constants like transmittivity, absorption coefficient, extinction coefficient, optical band gap and disorderness with no structural change. The optical transmittance decreased while absorption coefficient and extinction coefficient increased with increase in the fluence from 5 × 1012yions/cm2 to 5 × 1013ions/cm2. The decreased optical band gap with irradiation is explained on the basis of bond distribution model and density of defect states with increase in disorder. The p-type to n-type conductivity switching was observed at higher Bi content and the Hall measurement showed the increase in conductivity with irradiation. The Raman study on these ion irradiated films also confirmed no structural transformation. The surface morphological evolution of the films by Ag ion irradiation was studied by Field Emission Scanning Electron Microscopy.

In the present work, we probe into the phase transition of amorphous Bi10As40Se50 to a crystalline one upon thermal annealing. The Bi10As40Se50 thin films were prepared through thermal evaporation method and were annealed at 130° for 5h. The as-prepared and annealed films were characterized by XRD, FESEM and Raman spectroscopy. X-ray diffraction study revealed the amorphous nature of the as-prepared film and Bi3Se4 crystallite phase formation in the annealed film. This clearly indicates annealing induced diffusion of Bi into As2Se3 and hence the formation of Bi3Se4 phase. FESEM images show the smooth and homogeneous surface for the Bi10As40Se50 film whereas the annealed film shows these crystallites covers the surface. The Raman spectra shows a broad band corresponds to AsSe3 unit and a raman peak of bismuth selenide in the asprepared film whichshows shifting in case of annealed film.

The In/Se thin films were prepared by thermal evaporation method on glass substrate and were annealed at 200 °C for 1 hr. The indium diffusion into selenium matrix to form indium selenide phases like In2Se3, In4Se3 due to annealing was revealed from the X-ray diffraction study and also supported by the Raman spectra analysis. The optical band gap decreased with annealing as a result of different phase formation as studied from UV-visible spectroscopy. The formation of nano rod like structure in the as-prepared film and their disappearance upon annealing is probed by FESEM characterization.

Sensitivity of the anatase and rutile phases of titanium dioxide to Swift Heavy Ion (SHI) irradiation was experimentally probed and compared with the predictions of the Coulomb explosion, analytical and inelastic thermal spike models of ion-matter interaction. Conforming to the predictions of all these models, our study indicated higher sensitivity of anatase to these ions than the rutile phase. A detailed examination however revealed that Coulomb explosion model cannot explain either the nature of variation of the interaction cross section of SHI with the energy deposited by these ions, Se to the target electrons, or the relative values of the threshold electronic energy loss, Seth of anatase and rutile. The analytical thermal spike (a-TS) model, using the available physicochemical data for this oxide, predicted that tracks cannot form either in anatase or in rutile by 297 MeV and 511 MeV Ni ions, while inelastic thermal spike (i-TS) model predicted formation of ion tracks by 297 MeV Ni ions and their absence with 511 MeV Ni ions in both anatase and rutile. Our observation agreed with the predictions of i-TS model albeit with a difference in the radius of the tracks. In addition, we observed halo of defect ridden crystalline region of much larger radius around the ion track. Interestingly, the radius of the halo scales with the velocity of the ions, which is opposite to the conventionally observed velocity effect.

MoSi 2 coating has been developed on Nb-1Zr-0.1C alloy surface by firstly depositing Mo using magnetron sputtering technique and subsequent Si deposition by a chemical vapor deposition process namely pack siliconizing. About 2 μm thick interdiffusion zone is formed after annealing the Mo-coated Nb-alloy at 1500°C. The detailed characterization studies using XRF, SEM, EDS and EBSD of the pack siliconized coated alloy revealed the formation of an outer MoSi 2 layer and an inner NbSi 2 layer. About 25 μm thick MoSi 2 layer comprising of fine grained microstructure is formed at 1100°C.

This paper deals with numerical and experimental analyses of combustion of LPG (liquefied petroleum gas) (48% n-butane, 25% iso-butane, 23% propane, 4% ethane by mole fraction) in a domestic cooking stove with a two-layer porous radiant burner. The combustion zone consists of SiC matrix with 90% porosity, and the preheating zone is made of 3.0 mm diameter alumina balls. In the numerical study, for the 1-D planar geometry of the burner, the gas and the solid-phase energy equations, continuity equation, species conservation equation and ideal gas equation are simultaneously solved using the finite volume method. The volumetric radiation term appearing in the solid-phase energy equation is also computed using the finite volume method. Numerical results of temperature distributions, flammability limits and pollutant emissions for various equivalence ratios and thermal loads are found to have reasonably a good agreement with the experimental data. Towards improving the thermal performance of the cooking stove, effects of SiC matrix thickness, preheater thickness, solid-phase conductivity and scattering albedo on CO emissions and radiative flux are studied. In addition, following guidelines of the World Health Organization, the most effective burner on the basis of the minimum CO emission and the maximum thermal efficiency is proposed.