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Good-quality organic nonlinear single crystal of 2,3-dimethyl-N-[(E)-2,4,5-trimethoxy benzylidene] aniline (DTA) was synthesized and successfully grown at room temperature by adapting slow evaporation technique using mixed solvent of acetone and methanol. The crystal structure was experimentally confirmed by single-crystal X-ray diffraction, where the DTA crystals crystallize in the centric space group (P $$\overline{1}$$ ) with triclinic crystal system. The surface morphology of DTA was examined by the Field Emission Scanning Electron Microscope (FE-SEM) technique. The presence of various modes of functional groups of the title crystal was analyzed by Fourier-Transform Infra-Red (FT-IR) spectra. Ultraviolet–Visible-Near Infrared (UV–Vis–NIR) spectrum showed high optical transparency of ~ 88% in the Vis and NIR region with a UV–Vis absorption edge of 390 nm. The result of photoluminescence studies suggests that the DTA crystal can be used as source material to exhibit green emission light. From thermogravimetric-differential scanning calorimetry (TG-DSC) analysis, the melting point of the grown crystal was found to be 111 °C. The standard Z-Scan technique was employed to evaluate the third-order nonlinear optical properties of the DTA crystal. The obtained third-order nonlinear parameters were compared with few of the already reported NLO crystals. All these findings indicate that the title crystal may be an attractive material for nonlinear optical device applications.

Diphenylacetylene (DPAC) is a promising organic scintillator material for fast neutron detection. Solubility measurement was carried with two different solvents such as toluene and methanol. Stilbene mixed diphenylacetylene (DPACS) was successfully harvested from toluene with the dimensions of 42 × 12 × 8 mm3. X-ray diffraction confirms the monoclinic crystal structure with the obtained lattice parameters. The vibrational characteristic functional group was identified by FTIR studies. UV–Vis spectral analysis of the grown DPACS crystal reveals good optical transparency in visible and near IR region. The thermal behaviour and melting point of the sample was analysed by TGA-DSC. Chemical etching analysis was carried out on the crystal surface at an ambient temperature to see the dislocations and growth pattern of the crystal. Fluorescence broad emission peak was observed and the prompt and delayed fluorescence lifetimes of the DPACS were calculated.

Ammonium dihydrogen phosphate (ADP) is a pioneer kind of nonlinear optical crystal. It can be used in various electro-optical, nonlinear optical applications. The pure and different weight percentage of Picric acid doped ADP single crystals are grown using the slow solvent evaporation technique at room temperature. The powder XRD study shows single phasic nature of all the grown crystals. The photoluminescence study suggests that the dopant causes defect in structure of ADP by virtue of vibration relaxation and self trapping exciton. The dielectric constant and the dielectric loss of all the grown crystals exhibited universal behaviour over frequency range considered. The Correlation Barrier Hopping and the Non Overlapping Small Polaron Tunnelling kind of conductivity mechanism are observed. The grain and grain boundary is indentified using the complex Impedance and the complex modulus spectroscopy. The third order nonlinear optical susceptibility is increased on doping the Picric acid in ADP crystals. The results are discussed here.

Single crystals of Sm0.55Sr0.45Mn0.4Fe0.6O3were grown by an optical floating zone technique in an oxygen atmosphere. The powder X-ray diffraction pattern for the grown crystal revealed single-crystalline nature. The lattice parameters and atomic structure were refined and indexed using a General Structure Analysis System (GSAS) to an orthorhombic structure with lattice parametersa= 5.4415 (32) Å,b= 7.6994 (27) Å,c= 5.43868 (28) Å, and space group Pnma.

2-(2-Chloro-benzylidene)-Cyclododecanone, a cyclic ketone has been synthesized by direct aldol condensation reaction and the single crystals were grown in mixed solved (Tetrahydrofuran and ethanol) by slow evaporation method. The linear optical property of the crystal has been studied in the wavelength range 190 nm–1100 nm and optical constants were calculated theoretically. The saturation absorption and self-defocusing effect were observed in Z-scan technique. The magnitude of nonlinear refractive index (10−10 m2/W), nonlinear absorption (10−3 m/W) and third order nonlinear susceptibility (10−4 esu) has been calculated. The optical response time of the crystal is coming around 10−3 s.

In Additive manufacturing, direct metal laser sintering (DMLS) is a technique for manufacturing of Metal bases 3D printing. Finely pulverized metal is melted using a high-energy fibre laser, by Island principle strategy produces mechanically and thermally stable metallic components with reduced thermal gradients, stresses & at high precision. Al-Si10-Mg alloys are being used in aircraft and automobile parts. However, this component is susceptible to lack of hardness and corrosion resistance when exposed to higher load bearing operations and industrial environments. The laser shot peening of Al-Si10-Mg prepared by DMLS process was found to enhance micro hardness of aluminium alloy. The formation of closed packed and oriented micro grains of metal atoms at interstitial layers have been ascertained from SEM and TEM studies. AFM measurements revealed that formation of micro rough surfaces and also dislocation of new grains have significantly contributed to enhancement of mechanical properties of Al-Si10-Mg alloys

To doubling the frequency of Nd: YAG and Nd: YLF laser sources the ammonium dihydrogen phosphate (ADP) single crystal is widely used. In the present communication, the effect of amino acid namely as l-serine on the growth and properties of ADP crystal is been reported. The slow solvent evaporation technique is adopted to grow pure and different weight percentage i.e. 0.4 wt%, 0.6 wt% and 0.8 wt% l-serine doped ADP crystals. The structural study suggested tetragonal structure symmetry of all grown crystal with single phasic nature of all of them. The amino acid dopant alters the functional group vibrations of ADP crystal as suggested in FT-IR spectroscopy. The change in morphology and presence of various elements is observed in SEM and EDAX spectroscopy. The improvement is observed in various optical properties like energy band gap, skin depth, SHG, third order nonlinear susceptibility, laser damage threshold etc. on doping the l-serine in ADP crystal. The spectra variation of refractive index of all grown crystals is studied. The pure and l-serine doped ADP crystals have posses negative kind of photoconductivity.

The aimed study proposes laser shock peening without a coating of high strength ultrafine bainitic steel to mitigating the fatigue failures for automotive and structural engineering applications. Laser pulse density of 2500 pulses/cm2 (75% overlapping) was optimised based on the induced residual stresses for employing the wide range of characterisations. The roughness and topographic results showed that surface roughening was controlled by tuning the laser pulse density. The High-Resolution X-ray Diffraction analysis confirmed the lattice misorientation resulting peak shift and the trend towards martensite phase transformations. The electron microscopic micro/nanostructure analyses revealed the grain refinement features such as nano-twins, micro shear bands and shear cells. The work hardening depth analysis indicates the significant enhancement in the mechanical properties. Completely reversed (R = −1) high-cycle fatigue tests extended the lifespan by an average of five times than the untreated. Also, it has potential to repair the structural components effectively.

This research work investigates the effect of laser shock peening (LSP) on commercially pure titanium grade 1 (CP Ti-1) weldment. The welding was done using gas tungsten arc welding (GTAW) with ERTi-2 filler wire. LSP was carried out on the cap surface of the weldment. The optical microstructure showed the Widmanstatten-type martensitic structure in the fusion zone (as-welded). The LSP fusion zone showed a refined microstructure compared to that of as-welded condition. Scanning electron microscope (SEM) of LSP weldment showed the indentation on the surface of the weld. This was a result of the surface ablation that occurred during LSP. X-ray diffraction analysis showed the absence of transformation of phases in the weldment. A reduction of 14.8% of crystalline size was observed in LSP weldment. A higher compressive residual stress was observed in LSP weldment than the as-welded condition. Tensile test showed the occurrence of failure in the base metal region in the case of LSP weldment, as against the failure in the case of as-welded condition in the fusion zone.

The present work has important implications for the use of graphene as reinforcement and interlocking the grains in nanocomposites. In order to achieve this, low energy laser shock peening (LSP) assessed on graphene (0.4 wt %)-AA 7075 nanocomposites fabricated through powder metallurgy (PM) technique and hot extrusion (28:1 extrusion ratio). As a consequence, substantial improvement in microstructure observed for the nanocomposites up to 400 µm depth. The added graphene serves the pinning effect and blocks the grain growth in the nanocomposites. LSP contribute the additional grain refinement effectively along interlocking the grains by graphene called pinned dislocation core in the nanocomposites leading to large deformation texture strengthening. Addition of graphene found to have improved in the ultimate tensile strength (UTS) by 42.93%, LSP has contributed 10.66%.

(Bi1−xLax)(Fe,Co)O3 multiferroic magnetic film were fabricated using pulsed DC (direct current) sputtering technique and demonstrated magnetization reversal by applied electric field. The fabricated (Bi0.41La0.59)(Fe0.75Co0.25)O3 films exhibited hysteresis curves of both ferromagnetic and ferroelectric behavior. The saturated magnetization (Ms) of the multiferroic film was about 70 emu/cm3. The squareness (S) (= remanent magnetization (Mr)/Ms) and coercivity (Hc) of perpendicular to film plane are 0.64 and 4.2 kOe which are larger compared with films in parallel to film plane of 0.5 and 2.5 kOe. The electric and magnetic domain structures of the (Bi0.41La0.59)(Fe0.75Co0.25)O3 film analyzed by electric force microscopy (EFM) and magnetic force microscopy (MFM) were clearly induced with submicron scale by applying a local electric field. This magnetization reversal indicates the future realization of high performance magnetic device with low power consumption.

Pure and picric acid-added KDP (potassium dihydrogen phosphate) crystals are grown by slow evaporation technique from aqueous solution. Unit cell parameters for pure and doped KDP crystals were measured from single-crystal X-ray diffraction studies. Vickers and Knoop microhardness studies were carried out on the grown crystals over a load range of 0.1 to 0.5 N. The microhardness decreases with load P, i.e., normal indentation size effect (ISE), and from Meyers index it is shown that grown crystals falls in to hard material category. Mechanical properties, such as Young’s modulus, yield strength, elastic stiffness constant, were calculated for pure and doped KDP crystals. Hardness anisotropy has been observed in accordance with the orientation of the crystal. Etching studies were carried out using aqueous solution as an etchant. Improved second-harmonic generation efficiency is observed for doped KDP crystals in comparison to pure KDP crystals.

Hematite nanoparticles have been prepared from Moringa oleifera leaf extracts. Phytochemicals are derived from plant extracts which act as a stabilizing and capping agent as well as a surfactant. This green route protocol is attractive owing to its speed, reliability, and ecofriendly and cost-effective qualities. The synthesized iron oxide nanoparticles were subjected to three different calcination temperatures (500, 600, and 700°C). The crystallinity nature and phase purity have been confirmed by powder X-ray diffraction (PXRD). Optical properties have been studied by UV-visible (UV-vis) and diffuse reflectance spectroscopy (DRS). A very narrow bandgap was observed, and absorbance was observed at the visible region. Photoluminescence spectra have exhibited a multicolor emission band from the near UV to visible region due to defect centers (F centers). EDX (energy dispersive X-ray spectrum) has given information on the stoichiometric ratio of Fe and O. The functional groups which are responsible for nanoparticle formation have been identified by Fourier transformed infrared spectroscopy (FTIR), surface morphology transformation has been illustrated by scanning electron microscopy (SEM) studies, and VSM measurements have exhibited a hysteresis curve that shows the weak and strong ferromagnetic behavior in nature at RT. TEM micrographs have confirmed that particles are in the nanorange, matching the results from the XRD report. The SAED pattern gives information on the polycrystalline nature of hematite nanoparticles. TG-DSC characterization revealed phase transition, decomposition, and weight loss information. Frequency-dependent electrical properties were studied. Here, we report what the present studies have revealed: that hematite nanopowder prepared from the green route is environmentally friendly, takes a short time to prepare, is an economical and promising candidate material for electromagnetic devices and ferromagnet manufacturing, and is a photocatalyst in water treatment applications without adding additives (H2O2).

The pure and 0.1 wt% dl-methionine doped ADP crystals are grown using slow solvent evaporation technique at room temperature. The powder XRD study shows single phase nature of both grown crystals with tetragonal structural symmetry. The UV–Vis transmittance spectroscopy shows improvement in optical transmittance, energy band, and low refractive index of doped ADP crystal compare to pure ADP crystal. The Wemple–DiDomenico single oscillator model is found to be appropriate for the refractive index dispersion below the energy band edge of ADP crystal. The Nyquist plots of pure and doped ADP crystals represent presence of grain and grain boundary. The Jonscher’s powder law is successfully applied to the conductivity phenomena in pure and doped ADP crystals. The complex modulus spectroscopy helps to discriminate the grain and grain boundary in grown crystals clearly. The Non-Debye type relaxation is observed in both crystals. The nonlinear optical properties such as second harmonic generation efficiency and third order susceptibility are improved on doping the dl-methionine in ADP crystal.

Good quality, third order nonlinear optical single crystal, 2-(4-ethylbenzylidene) malononitrile (EBM) was successfully grown by slow evaporation solution growth technique (SESGT) at room temperature using ethanol solvent. The formation of new crystalline structure, packing array and features of the molecular geometry were confirmed through the single crystal X-ray diffraction analysis. And also, it is addressed that, crystal belongs to the monoclinic system with centrosymmetric space group P21/c. The morphology of the EBM crystal is simulated with the help of WinXMorph software. The crystalline purity and multifarious functional groups of the EBM were ascertained by powder XRD and FT-IR analyzes, respectively. The Uv–Vis–NIR spectral study directs the way to find the lower cut-off wavelength (λ = 427 nm) and transparency (∼76%) of the grown specimen. The band gap of the EBM is estimated to be 2.92 eV. The photoluminescence spectrum of the crystal reveals that, it can be served as a new green lighting material. The quite low dielectric responses of EBM play a noticeable role in micro-electronics device application. The low etch pit density (EPD) is great evidence for the crystalline perfection of the titular crystal. The laser induced surface damaged threshold (LDT) value of inclusion free EBM crystal is 2.11 GW cm-2, it is quite good as compared with previously reported crystals. The effective third order optical nonlinearity of the title crystal has been investigated systematically using typical Z-scan technique. All these findings are addressed to the EBM crystal which is smart candidate for the NLO applications.

A cyclic ketone, cyclododecanone (CDD) and its derivatives has been synthesized by direct aldol condensation reaction. CDD derivative (–CH3, –OMe, –2Br, –2Cl, –4Cl, 2CF3, –C6H6) crystals were grown in the mixture of solvent tetrahydrofuran and ethanol by Natural evaporation method. The linear optical property of CDD derivative crystals has been studied using UV–Vis–NIR spectroscopy. The optical constants are calculated theoretically in the wavelength range 190–1100 nm. The third order nonlinear optical property of CDD derivatives has investigated by using z-scan technique using He–Ne laser (632.8 nm). The saturation absorption and self-defocusing effect was observed in z-scan open and closed aperture methods respectively. The nonlinear optical effects were due to the thermal mechanism processes of the incident laser power passing through an optical material. The response time of CDD derivative has found to be in the order of milliseconds. The two figures of merit W > 1 and T

Hybrid inorganic nonlinear optical crystals find huge applications in laser assisted photonic devices therefore present communication firstly aims to investigate the dielectric, microscopic and linear-nonlinear optical properties of ammonium zinc sulphate hydrate (AZSH) crystal. The inorganic AZSH complex has been synthesized and 15 × 10 × 09 mm3 single crystal was grown by slow solvent evaporation method. The powder and single crystal X-ray diffraction technique has been employed to evaluate the crystalline phase and determine the structural parameters of AZSH crystal. The optical transparency of AZSH crystal has been examined within the wavelength rage of 200–1100 nm. The enhanced second harmonic generation efficiency of AZSH crystal is 2.53 times higher than standard KDP crystal. The laser damage threshold of AZSH crystal has been determined using the Nd:YAG laser operating at 1064 nm. The close and open aperture Z-scan studies have been performed to ascertain the nature of third order nonlinear optical (TONLO) refraction and absorption of AZSH crystal. The order of TONLO parameters n2, β and χ3 is found to be 10−9 cm2/W, 10−4 cm/W, 10−4 esu respectively. The AZSH crystal is found to have violet colored luminescence emission centered at 370 nm. The dielectric constant and dielectric loss of AZSH crystal has been evaluated within 30 Hz to 1 MHz. The chemical etching technique has been imposed to examine the growth habitat and determine the etch pit density of AZSH crystal.

4-N,N-dimethylamino-4′-N′-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate (DSTMS) terahertz organic material has been synthesized by the knoevenagel condensation method. DSTMS single crystals were grown in methanol by slow-cooling method. The linear optical property of DSTMS crystal has been studied using UV–Vis-NIR spectroscopy in the wavelength range 190–1100 nm and optical constants are calculated theoretically. The magnitude of nonlinear refractive index (10−10 m2/W), nonlinear absorption (10−3 m/W) and third order nonlinear susceptibility (10−4 esu) has been studied using Z-scan technique. Dielectric property of DSTMS crystal has been studied at frequency range 50 Hz–5 MHz. The electronic properties such as valence electron plasma energy, penn gap, fermi energy, electronic polarization, electric susceptibility of the grown crystal has been studied. Photoluminescence spectrum was recorded using xenon lamp in the range of 450–700 nm. Laser optical damage threshold of DSTMS crystal was calculated (3.57 GW/cm2) using pulsed Nd-YAG laser (1064 nm) of repetition rate 10 ns. The refractive index of the crystal (1.571) has been measured using Abbe’s Refractometer. The optical limiting behaviour of DSTMS crystal has been studied using Nd-YAG laser. The response time (τ) of optical limiting power for the crystals is 10−11 s.

The search for organic crystals with high efficient fast neutron detection with short decay time have become more demand nowadays. These are being used in the frontline areas in radiation medicine, neutron spectroscopy and special nuclear material detection. We explored the growth progress and characterized the pure and stilbene doped bibenzyl (BBS) organic scintillator crystal by solution growth technique. The solubility of bibenzyl was determined in methanol by thermogravimetric method. The grown crystal was subjected to single X-ray diffraction to find the cell parameters which shows the monoclinic structure. The crystallinity was examined by powder X-ray diffraction pattern. Fourier transform infrared spectra was carried out for the doped crystal and compared that of pure bibenzyl (BB) crystal. The absorption and transmittance range were measured by UV-Vis-NIR analysis. The emission spectrum was measured by photoluminescence, two significant peaks were observed at 353 and 373 nm. The grown BBS crystal decay time 0.8 and 1.65 ns was calculated for prompt and delayed emission by using pulsed nano-LED source. Thermal steadiness of BBS was verified by thermo-gravimetric and differential scanning calorimetry.

2-(4-fluorobenzylidene) malononitrile (FBM), an organic third order nonlinear (TONLO) single crystal with the dimensions of 32 × 7 × 11 mm3, has been successfully grown in acetone solution by slow evaporation technique at 35 °C. The crystal system (triclinic), space group (P-1) and crystalline purity of the titular crystal were measured by single crystal and powder X-ray diffraction, respectively. The molecular weight and the multiple functional groups of the FBM material were confirmed through the mass and FT-IR spectral analysis. UV–Vis–NIR spectral study enroles that the FBM crystal exhibits excellent transparency (83%) in the entire visible and near infra-red region with a wide bandgap 2.90 eV. The low dielectric constant (er) value of FBM crystal is appreciable for microelectronics industry applications. Thermal stability and melting point (130.09 °C) were ascertained by TGA-DSC analysis. The laser-induced surface damage threshold (LDT) value of FBM specimen is found to be 2.14 GW/cm2, it is fairly good compared to other reported NLO crystals. The third - order nonlinear optical character of the FBM crystal was confirmed through the typical single beam Z-scan technique. All these finding authorized that the organic crystal of FBM is favorably suitable for NLO applications.

Potassium pentaborate (KB5) is an excellent nonlinear optical material especially in the UV region. In this work, Li and NH4 doped KB5 crystals were grown using slow evaporation solution growth method. The incorporation of dopant has been confirmed and analysed by Energy dispersive X-ray analysis (EDAX), Inductively coupled plasma (ICP) analysis and Raman spectroscopy. The crystalline perfection of pure and doped KB5 crystals was studied by High resolution X-ray diffraction (HRXRD) analysis. Structural grain boundaries were observed in doped crystals. Second harmonic generation was confirmed for pure and doped crystals and output values revealed the enhancement of SHG efficiency in doped crystals. Resistance against laser damage was carried out using 1064 nm Nd-YAG laser of pulse width 10 ns. The laser damage threshold value is increased in Li doped crystal and decreased in NH4 doped crystal when compared to pure KB5 crystal.

Single crystals of high concentration iron substituted Sm 0.55 Sr 0.45 Mn 0.4 Fe 0.6 O 3 were grown by optical floating zone technique in oxygen atmosphere. Analysis of powder X-ray diffraction and Laue patterns revealed single-phase formation and crystal quality respectively. Replacement of Mn by iron has reduced the ratio of trivalent to tetravalent Mn ions thus suppressing the double exchange interactions and ferromagnetism. The grown crystal exhibits spin glass behavior below 35 K due to the competition between the Mn 3+ -O-Mn 4+ double exchange and the Mn 3+ -O-Fe 3+ super exchange interactions.

The derivative of an organic stilbazolium single crystal, (E)-1-ethyl-2-(4-nitrostyryl) pyridin-1-ium iodide (hereafter abbreviated as NSPI), was synthesized by the Knoevenagel condensation method. Single crystal of NSPI of size 13 × 12 × 3 mm3 were obtained from a 1:1 ratio of methanol and acetonitrile mixed solvent using the slow evaporation technique. X-ray structural analysis has indicated that NSPI crystallizes in the centric triclinic system with the P1 space group. In addition, Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopic analyses were carried out to confirm the molecular structure of the grown crystal. The small energy difference of the frontier molecular orbitals indicates the possible nonlinear optical properties present in the title crystal. Thermal studies confirm that the material has a good thermal stability of about 151 °C. Etching studies provide the layered growth of the NSPI crystal with fewer dislocations. The optical transmission range and the b...

Organometallic crystals offer considerable nonlinear response therefore, present article focuses on bulk growth and investigation of Cu2+ ion doped zinc thiourea chloride (ZTC) crystal to explore its technological impetus for laser assisted nonlinear optical (NLO) device applications. The Cu2+ ion doped ZTC bulk single crystal of dimension 03 × 2.4 × 0.4 cm3 has been grown from pH controlled aqueous solution by employing slow solvent evaporation technique. The structural analysis has been performed by means of single crystal X-ray diffraction technique. The doping of Cu2+ ion in ZTC crystal matrix has been confirmed by means of energy dispersive spectroscopic (EDS) technique. The origin of nonlinear optical properties in Cu2+ ion doped ZTC crystal has been studied by employing the Kurtz-Perry test and Z-scan analysis. The remarkable enhancement in second harmonic generation (SHG) efficiency of Cu2+ ion doped ZTC crystal with reference to ZTC crystal has been determined. The He-Ne laser assisted Z-scan analysis has been performed to determine the third order nonlinear optical (TONLO) nature of grown crystal. The TONLO parameters such as susceptibility, absorption coefficient, refractive index and figure of merit of Cu-ZTC crystal have been evaluated using the Z-scan transmittance data. The laser damage threshold of grown crystal to high intensity of Nd:YAG laser is found to be 706.2 MW/cm2. The hardness number, work hardening index, yield strength and elastic stiffness coefficient of grown crystal has been investigated under microhardness study. The etching study has been carried out to determine the growth likelihood, nature of etch pits and surface quality of grown crystal.

We have theoretically and experimentally studied the tailoring of intermediate bands in the CuGa1-xFexS2 chalcopyrite system. An ab initio density functional theory calculations within GGA + U approach have been performed to model pristine and Fe-doped CuGaS2 to understand their structural and electronic properties and thereby understand the origin of intermediate states produced with Fe doping. Thin films of the pristine and Fe-doped CuGaS2 of various compositions are deposited using chemical spray pyrolysis for the experimental studies. The crystal structure, morphology, and topography of the deposited thin films are examined using Powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM), respectively. The binding energy and chemical composition of CuGa0.95Fe0.05S2 thin films are determined using X-ray Photoelectron Spectroscopy (XPS). The direct and intermediate band optical responses have been probed through UV–Vis–NIR Spectroscopy. Pristine CuGaS2 exhibits a direct bandgap of 2.43 eV, with formation of intermediate bands in Fe-doped CuGaS2 at 1.82 eV, 1.75 eV, 1.54 eV and 1.49 eV with varying Fe atomic percentage (X = 0.025, 0.05, 0.075, and 0.1 at. %). The optimum Fe concentration is determined to be X = 0.05 (CuGa0.95Fe0.05S2) as it exhibits the highest photocurrent (1.46 mA), electrical conductivity, and intermediate band optical response. The IB formation is further supported by the calculated density of states of the Fe doped CuGaS2 structure.

The ammonium dihydrogen phosphate (ADP) crystals have wide range of non-linear optical applications. The doping of bivalent impurity like strontium can strongly retard growth rate and modify properties of ADP crystals. The pure and 0.5 mol% Sr2+ doped ADP crystals are grown by using the slow evaporation technique at room temperature. The powder XRD indicates the single phase nature of both samples. The FT-IR spectra indicate the shifting of absorption peaks for the doped sample. The thermal study indicates that the doped sample is thermally less stable than the pure sample. The EDAX study confirms the presence of strontium in the doped sample. The UV–Vis spectra indicate slight decrement in the transmittance due Sr2+ doping. The Wemple–DiDomenico model is satisfactorily applied to dispersive behaviour of refractive index. The dielectric constant and dielectric loss decreases with frequency increased. The Jonscher’s power law is studied for A.C. conductivity. The Nyquist plot and complex modulus plot exhibits two semicircles for pure ADP due to grain and grain boundary contributions and the same plots show single semicircle for doped ADP due to grain contribution only. The stretch exponent (β) is obtained less than unity, indicates the non-Debye type relaxation process. The second harmonic generation efficiency of fundamental laser beam is found to be 2.07 and 1.54 times higher than the pure KDP for pure ADP and Sr2+ doped ADP, respectively. The Z-scan study reveals the self focusing and reverses saturable absorption kind of nonlinear response for both samples.

Low energy laser shock peening without coating (LSPwC) was conducted on AISI 304 austenitic stainless steel specimens with varying pulse densities or overlapping. Highest magnitude of compressive residual stress (CRS) was achieved for an optimized pulse density of 2500 pulses/cm 2 (75% overlapping). The 2-D and 3-D topographical analysis were indicative of the fact that controlled roughening of the surface was achieved after the LSPwC process. After the LSPwC process, the hydrophilic unpeened surface was converted into the hydrophobic surface, thus decreasing the wettability characteristics of the surface. The X-ray diffraction (XRD) results reveal that there is a beginning of the martensite transformation and the rise in the intensity value of the peaks after LSPwC indicates the presence of compressive residual stresses induced in the specimen. The optical microscope and high-resolution transmission electron microscope results provided evidence of grain refinement and deformation induced refinement features such as multidirectional mechanical twinning, dislocations lines, micro shear cells and stacking faults in the near and sub-surface areas. The average hardness value of the LSPwC specimens was found to be increased by 28% more than the untreated specimen. The potentiodynamic polarization revealed that there was a considerable amount of increase in the pitting corrosion resistance after the LSPwC process, thus, supporting to extend the fatigue life of the specimen. The electrochemical impedance spectroscopic (EIS) analysis depicts that the LSPwC process supports the formation of the strong passivation layer in 3.5% NaCl solution.

Present competitive world is looking for Components with high strength and fatigue resistance finding their applications in aerospace, turbine parts and especially bio-medical devices with high bio-compatibility. Advanced engineering techniques are required to produce parts of higher complexities and desirable surface qualities. Laser peening stood first in a row of all various surface treatments of metallic component. A Fundamental purpose of nobility of the nearby variations in residual stress that happen inside the processed region, that are sensitive to processing variables and not effectively measured tentatively. The rule of residual .stress .is important .in guaranteeing .the nobility of engineering segments and Laser. Shock. Peening (LSP) process .can be utilized to great impact to present the gainful compressive residual. stress .levels as required. It is, nonetheless, hard to utilize ordinary laser. peening .rule .frameworks to set up the perfect peening .state that. will bring about the best .execution. This .paper.. results .from .a study .to optimize the .laser .peening .parameters. for a typical. titanium.. ND- YAG laser equipment was taken for the experimental work and statistical Taguchi technique was .used .to bound .the number .of experiments .necessary .for optimization .to be feasible.

Tailoring sub-bandgaps using intermediate states or bands with wide bandgap semiconductors is a promising and novel technique for the application in high efficiency solar cells. Pure and chromium (Cr) doped chalcopyrite CuGaS2 (CGS) thin films were prepared by facile chemical spray pyrolysis technique and annealed in vacuum, nitrogen and argon atmospheres. Structural characterization confirmed that the prepared films are in tetragonal chalcopyrite structure with polycrystalline nature. No secondary phases were present in both pure and Cr doped CGS thin films. Presence of Cr ions was confirmed by X-ray photoelectron spectroscopy and energy dispersive analysis of X-rays analyses. The optical direct and sub band gap of pristine and Cr doped CGS thin films were measured from UV absorption data. It was revealed that the pure CGS film has a band gap of 2.40 eV sub-band gap values were observed at 2.25 and 2.15 eV for 1 and 2 wt% of Cr doping, respectively. These gaps can be ascribed to the formation of intermediate bands due to hybridization of Cr d-states into the host electronic structure. Meanwhile, photoconductivity study demonstrated the photo-electric activity of the intermediate bands in the Cr doped thin films.