High-resolution X-ray Diffraction Studies Research Articles

Mg incorporation induced microstructural evolution of reactively sputtered GaN epitaxial films to Mg-doped GaN nanorods

Mg-doped GaN films/nanorods were grown epitaxially on c-sapphire by reactive co-sputtering of GaAs and Mg at different N2 percentages in Ar–N2 sputtering atmosphere. Energy dispersive x-ray spectroscopy revealed that the Mg incorporation increases with increase of Mg area coverage of GaAs target, but does not depend on N2 percentage. In comparison to undoped GaN films, Mg-doped GaN displayed substantial decrease of lateral conductivity and electron concentration with the initial incorporation of Mg, indicating p-type doping, but revealed insulating behaviour at larger Mg content. Morphological investigations by scanning electron microscopy have shown that the films grown with 2%–4% Mg area coverages displayed substantially improved columnar structure, compared to undoped GaN films, along with rough and voided surface features at lower N2 percentages. With increase of Mg area coverage to 6%, the growth of vertically aligned and well-separated nanorods, terminating with smooth hexagonal faces was observed in the range of 50%–75% N2 in sputtering atmosphere. High-resolution x-ray diffraction studies confirmed the epitaxial character of Mg-doped GaN films and nanorods, which displayed complete c-axis orientation of crystallites and a mosaic structure, aligned laterally with the c-sapphire lattice. The catalyst-free growth of self-assembled Mg-doped GaN nanorods is attributed to increase of surface energy anisotropy due to the incorporation of Mg. However, with further increase of Mg area coverage to 8%, the nanorods revealed lateral merger, suggesting enhanced radial growth at larger Mg content.

MBE-grown tetragonal FeTe consisting of c-axis-aligned nanocrystals

Tetragonal FeTe grown on c-plane sapphire by the molecular beam epitaxy technique is found to result in a new structural phase consisting of c-axis-aligned nanocrystals. Their reflection high-energy electron diffraction patterns display two sets of streaks simultaneously at all rotation angles of the sample. High-resolution x-ray diffraction studies confirm that the nanocrystals are tetragonal FeTe with their c-axes aligned to the growth direction. Atomic force microscopy imaging reveals that further growth of these nanocrystals involves a cannibalism process resulting in nanocrystal pillars with sizes of about 0.5–1 µm. The temperature-dependent resistance of these thin films displays an overall semiconducting behavior, however, with a non-measurable state or jumps and falls depending on their nominal thickness, which can be attributed to the thermal responses of the nanocrystals during cooling and heating processes. This discovery provides an approach to form inhomogeneous heterostructures with all possible twisted angles.

Investigating the structural and mechanical behavioral properties of semi-organic nonlinear optical single crystal: L-arginine tetrafluoroborate

A semi-organic nonlinear optical material L-Arginine tetrafluoroborate (LAFB) was synthesized as single crystal using Slow Evaporation Technique. Various properties of this material were analyzed to make it suitable for NLO applications. The structural behavior of the material was determined by single crystal XRD and found that the crystal has orthorhombic structure and was synthesized with P212121 space group. The High-Resolution X-Ray Diffraction (HRXRD) study was conducted to determine the change in the lattice parameters resulting from strain, defects or by other means in LAFB material. The diffraction curve analysis show that the grown crystal consisted of interstitial type point defect. The Shock Damage Threshold (SDT) measures the stability of the compound against shock, the analysis exhibits that under Mach number 2.2 up to 10th shock no significant cracks were observed in the crystal but damage area of the crystal was increased. The mechanical behavior of the sample against highly intense laser was analyzed through Laser Damage Threshold (LDT). The calculated value of LDT was to be 0.75[Formula: see text]GW/cm2 for 1 pulse per second whereas it decreased to 0.57[Formula: see text]GW/cm2 for 10 pulse per second. To explore the mechanical properties of the material, Nano indentation was carried out, by which the values of H[Formula: see text][Formula: see text]MPa and E[Formula: see text][Formula: see text]GPa were obtained.

Modified matrix of ZnO prismoid structures for improved photocatalytic activity: A theoretical and experimental insight

Currently, the world needs low-cost and high-performance photocatalysts to degrade the carcinogenic pollutant from water. In the present work, a modified ZnO matrix using Mg as a dopant has been reported with theoretical and experimental results to highlight its structure and functions on photocatalytic activity. A versatile chemical co-precipitation technique was employed to get the Mg-ZnO nanostructures. Structural characterization by high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) studies show the formation of hexagonal wurtzite structures with no impurity phases. Optical studies confirm the formation of ZnO with intrinsic defects after modifying the matrix, which agrees with the band structure calculations computed using density functional theory (DFT). Mg-modified ZnO introduced intrinsic defects like vacancies and interstitials that have a great impact on applications like photocatalysis. Based on these supporting results we employed prepared samples for dye degradation, which performed well (80% degradation efficiency) in a short period of UV irradiation. This could be a promising technology for environmental remediation.

Effect of Stereochemically Active Electron Lone Pairs on Magnetic Ordering in Trivanadates.

Stereoactive electron lone pairs derived from filled 5/6s2 states of p-block cations are an intriguing electronic and geometric structure motif that have been exploited for diverse applications such as thermoelectrics, thermochromics, photocatalysis, and nonlinear optics. Layered trivanadates are dynamic intercalation hosts, where the insertion of cations can be used to tune electron correlation, charge localization, and magnetic ordering. However, the interaction of 5/6s2 stereoactive electron lone pairs with layered trivanadates remains unexplored. In this study, we contrast s- and p-block trivanadates and map off-centering in the coordination environment and reduction in symmetry arising from the stereochemical activity of lone pair cations to the emergence of filled antibonding lone-pair 6s2-O 2p hybridized states. The former is studied by high-resolution single-crystal X-ray diffraction studies of TlV3O8 and isostructural RbV3O8 to probe distinct differences in Tl and Rb coordination environments and the resulting modulation of V-V interactions in V3O8 slabs. The latter has been probed by variable-energy hard X-ray photoelectron spectroscopy (HAXPES) measurements, which manifest orbital-specific contributions from bonding and antibonding interactions of stereoactive Tl 6s2 electron lone pairs in TlV3O8. The spectroscopic assignment of valence band states to stereoactive lone pairs is further corroborated by first-principles electronic structure calculations, crystal orbital Hamilton population analyses, and electron localization function maps. The presence of the Tl 6s2 electron lone pair in TlV3O8 brings about the off-centering of Tl+ cations, which leads to anisotropy in Tl-O bonds. The off-centering of Tl ions weakens V-O bonds in one direction, which subsequently strengthens directional V-V coupling. Magnetic measurements reveal ferromagnetic signatures for both RbV3O8 and TlV3O8. However, the differences in V···V interactions significantly affect the energy balance of the superexchange interactions, resulting in an ordering temperature of 140 K for TlV3O8 as compared to 125 K for RbV3O8. The results demonstrate the distinctive effects of stereochemically active lone pairs in modifying electronic structure near the Fermi level and for mediating superexchange interactions.

Growth of quasi-1 dimensional (Bi1−x Sb x )2S3 nanowires on fluorine-doped tin oxide glass substrate by vapor transport

(Bi1−x Sb x )2S3 solid solution nanowires () are grown on fluorine-doped tin oxide (FTO) glass via physical vapor transport. The compositions were controlled by varying the Sb2S3 source temperature (300 °C–453 °C) by changing the upstream locations of the Sb2S3 source in the furnace while keeping the Bi2S3 source at the center of the furnace (497 °C). Defect-free nanowires with phase-pure orthorhombic and quasi-1 dimensional crystal structures were grown under a modified vapor–solid mechanism affected by FTO at initial growth stage. The aspect ratios of the nanowires reached the minimum at composition As the Sb2S3 source approached the Bi2S3 source, x increased owing to the increase in the Sb2S3 source temperature. x/(1-x), which is proportional to the evaporation flux of the Sb2S3 source, could be well-fitted with a thermally activated equation with an apparent activation energy ( ). However, at the distance between the Sb2S3 and Bi2S3 sources, with the Sb2S3 source at temperatures higher than 410 °C, the compositions reduced despite the increased Sb2S3 evaporation flux. Such retrograde behavior was confirmed by high-resolution transmission electron microscopy, x-ray diffraction, and micro-Raman studies. This retrograde behavior is ascribed to the loss due to the reaction of gaseous Sb species with the Bi2S3 source.

Ligand-Receptor Interactions of Lamivudine: A View from Charge Density Study and QM/MM Calculations

The nature and strength of interactions for an anti-HIV drug, Lamivudine, were studied in a pure crystal form of the drug and the ligand-receptor complexes. High-resolution single-crystal X-ray diffraction studies of the tetragonal polymorph allowed the drug's experimental charge density distribution in the solid state to be obtained. The QM/MM calculations were performed for a simplified model of the Lamivudine complex with deoxycytidine kinase (two complexes with different binding modes) to reconstruct the theoretical charge density distribution. The peculiarities of intramolecular interactions were compared with previously reported data for an isolated molecule. Intermolecular interactions were revealed within the quantum theory of 'Atoms in Molecules', and their contributions to the total crystal energy or ligand-receptor binding energy were evaluated. It was demonstrated that the crystal field effect weakened the intramolecular interactions. Overall, the energies of intermolecular interactions in ligand-receptor complexes (320.1-394.8 kJ/mol) were higher than the energies of interactions in the crystal (276.9 kJ/mol) due to the larger number of hydrophilic interactions. In contrast, the sum of the energies of hydrophobic interactions was found to be unchanged. It was demonstrated by means of the Voronoi tessellation that molecular volume remained constant for different molecular conformations (250(13) Å3) and increased up to 399 Å3 and 521(30) Å3 for the Lamivudine phosphate and triphosphate.

Sawtooth lattice multiferroic BeCr2O4 : Noncollinear magnetic structure and multiple magnetic transitions

Noncollinear magnetic structures and multiple magnetic phase transitions in a sawtooth lattice antiferromagnet consisting of ${\mathrm{Cr}}^{3+}$ are experimentally identified in this work, thereby proposing the scenario of magnetism-driven ferroelectricity in a sawtooth lattice. The title compound, ${\mathrm{BeCr}}_{2}{\mathrm{O}}_{4}$, displays three magnetic phase transitions at low temperatures---at ${T}_{N1}\ensuremath{\approx}7.5$ K, at ${T}_{N2}\ensuremath{\approx}25$ K, and at ${T}_{N3}\ensuremath{\approx}26$ K---revealed through magnetic susceptibility, specific heat, and neutron diffraction in this work. These magnetic phase transitions are found to be influenced by externally applied magnetic fields. Isothermal magnetization curves at low temperatures below the magnetic transitions indicate the antiferromagnetic nature of ${\mathrm{BeCr}}_{2}{\mathrm{O}}_{4}$ with two spin-flop-like transitions occurring at ${H}_{c1}\ensuremath{\approx}29$ kOe and ${H}_{c2}\ensuremath{\approx}47$ kOe. Our high-resolution x-ray and neutron diffraction studies, performed on single crystal and powder samples, unambiguously determined the crystal structure as orthorhombic $Pbnm$. By performing the magnetic superspace group analysis of the neutron diffraction data at low temperatures, the magnetic structure in the temperature range ${T}_{N3,N2}<T<{T}_{N1}$ is determined to be the polar magnetic space group $P21nm.{1}^{\ensuremath{'}}(00g)0s0s$ with a cycloidal magnetic propagation vector ${\mathbf{k}}_{1}=(0,0,0.090(1))$. The magnetic structure in the newly identified phase below ${T}_{N1}$ is determined as $P21/b.{1}^{\ensuremath{'}}[b](00g)00s$ with the magnetic propagation vector ${\mathbf{k}}_{2}=(0,0,0.908(1))$. The cycloidal spin structure determined in our work is usually associated with electric polarization, thereby making ${\mathrm{BeCr}}_{2}{\mathrm{O}}_{4}$ a promising multiferroic belonging to the sparsely populated family of sawtooth lattice antiferromagnets.

Crystal growth, structural and DFT study of novel single crystal (E)-N’-(2-chlorobenzylidene)-4-fluorobenzohydrazide for nonlinear optical applications

Nonlinear optical (NLO) material, (E)-N'-(2-chlorobenzylidene)-4-fluorobenzohydrazide (CBBH) novel single crystal was grown via a Schiff base chemical reaction. A single crystal X-ray diffraction technique was utilized for the recognition of the crystal structure of the CBBH. The imperfection of novel CBBH crystal was checked by high resolution X-ray diffraction (HRXRD) study. Hirshfeld surface study through colour coding was applied to know the intra and intermolecular force interactions. Fourier transforms infrared (FTIR), proton 1H and carbon 13C nuclear magnetic resonance (NMR) spectra were employed to elucidate the various functional groups and structure of the crystal. The absorption maxima from UV–Vis plot for the CBBH molecule was found at 314 nm, which reveals the π-π* transition. Photololuminescence (PL) study reveals that emission observed in the blue-violet region. The HOMO and LUMO energies were investigated using the density functional theory (DFT) method. Natural bond orbital (NBO) analysis explored the donor-acceptor exchanges and it's endurance into intra-molecularly. The first-order hyperpolarizability value, β0 = 23.73 × 1030 esu was observed for CBBH crystal, which is ∼64 times larger than that of urea molecule (0.3728 × 1030 esu). Z-scan experiment on CBBH crystal supports its third-order nonlinear optical (NLO) properties. Optical limiting analysis indicates reverse saturation absorption behavior of CBBH crystal.

Electronic phase transition in the Re3Ge7 endohedral cluster compound

${\mathrm{Re}}_{3}{\mathrm{Ge}}_{7}$ is a unique electronic material showing low-temperature metal--insulator-like phase transition. Furthermore, bulk superconductivity can be induced in ${\mathrm{Re}}_{3}{\mathrm{Ge}}_{7}$ by hole doping. Here, we present transport properties, temperature-dependent high-resolution powder x-ray diffraction study, and electronic structure of ${\mathrm{Re}}_{3}{\mathrm{Ge}}_{7}$ in the vicinity of the electronic phase transition. Electrical resistivity and heat capacity measurements confirm the anomaly at 58.5 K in zero magnetic field. The Seebeck coefficient changes its sign and exhibits a maximum below the transition temperature indicating substantial changes in the electronic structure. Temperature-dependent structural studies confirm the second-order nature of phase transition, where unit cell parameters show abrupt change at the transition temperature. An analysis of interatomic distances indicates that the shrinkage of the unit cell volume is due to the interatomic changes taking place in the second coordination sphere of Re atoms. Electronic structure calculations reveal strong $5d\ensuremath{-}4p$ hybridization of valence orbitals near the Fermi level, which is situated between two deep pseudogaps of the density of states. The transition to the semiconducting state is accompanied by the opening of a band gap at the Fermi level right above the narrow pocket of hybridized states.

Insights into the structural symmetry of YCrO3 from synchrotron X-ray diffraction

A high-resolution synchrotron X-ray diffraction study of a single-crystal YCrO3 compound was employed to obtain its crystallographic information, such as lattice parameters, atomic positions, bond lengths and angles, and local crystalline distortion size and mode. The measurements were taken at 120 K (below the antiferromagnetic transition temperature T N ≃ 141.5 K), 300 K (between T N and the ferroelectric transition temperature T C ≃ 473 K) and 500 K (above T C). Using the high intensity of synchrotron X-rays, it was possible to refine collected patterns with the previously proposed noncentrosymmetric monoclinic structural model (P1211, No. 4) and determine detailed structural parameters. Meanwhile, for a controlled study, the data were refined with the centrosymmetric orthorhombic space group (Pmnb, No. 62). The lattice constants a, b and c and the unit-cell volume increased nearly linearly upon heating. With the P1211 space group, the distributions of bond lengths and angles, as well as local distortion strengths, were observed to be more dispersed. This implies that (i) the local distortion mode of Cr2O6 at 120 K correlates with the formation of canted antiferromagnetic order by Cr1–Cr2 spin interactions, primarily via intermediate O3 and O4 ions; and (ii) the previously reported dielectric anomaly may have a microscopic origin in the strain-balanced Cr1—O3(O4) and Cr2—O5(O6) bonds as well as the local distortion modes of Cr1O6 and Cr2O6 octahedra at 300 K. Local crystalline distortion is shown to be an important factor in the formation of ferroelectric order. The comprehensive set of crystallographic information reported here allows for a complete understanding of the unique magnetic and ferroelectric properties of YCrO3.

High resolution X-ray diffraction study in InAs/GaSb superlattice

In our experiment, the high-resolution X-ray diffraction rocking curves and AFM morphology of InAs/GaSb superlattices with different periods, thicknesses and soaked time are studied, which were grown by molecular beam epitaxy. We get the structural parameters of high-quality InAs/GaSb superlattices. During the growth process, the short-period InAs/GaSb superlattice has larger root mean square roughness than the long period, poor surface uniformity and weak stress release ability. The use of multi-period structure can better overcome stress and mismatch, the X-ray diffraction peak is modulated due to the change of InAs layer thickness and GaSb layer thickness. Through the position and distribution of diffraction peak, the strain characteristics of superlattice structure can be obtained, and then the regulation of energy band structure and shape of high-quality InAs/GaSb superlattice can be realized, which indicates good perspective for multi-period structure devices.

Evidence of Delta Phase of Fe in MBE-Grown Thin Epitaxial Films on GaAs

Fe/GaAs is an important system for the study of spin injection behavior that can vary with the nature and interfaces of Fe films. Here, we investigate the effect of interfacial strain on the microstructure, interfaces and phase-formation behavior in epitaxially grown Fe films. To vary the strain, we have characterized Fe films of various thicknesses ranging from 10 to 1000 nm which were grown using molecular beam epitaxy on GaAs (011) and AlGaAs (001) substrates. High resolution X-ray diffraction studies revealed that films with higher thicknesses exhibited an equilibrium α-Fe phase, while the films with less than 10 nm thicknesses indicated the presence of δ-Fe. Transmission electron microscopy revealed the interface for 10-nm-thick films had strain lobes with no interfacial phase formation for films deposited at room temperature. At a higher deposition temperature of 175 °C, similar strain lobes were observed for a 10-nm-thick film. Extended annealing at 200 °C transformed the metastable δ-Fe phase to an equilibrium α-Fe. However, at higher temperature, the interface contained an intermixing layer of (FeAl)GaAs. We demonstrate that the interfacial strain plays a major role in stabilizing the metastable δ-Fe on GaAs.

Mosaic growth induced magnetic anisotropy in double perovskite PrBaCo2O5+δ thin films

Controlling crystal structure is one of the most crucial steps for tuning the physical properties in layered perovskite oxides. The growth of mosaic-patterned double perovskite PrBaCo2O5+δ (PBCO) thin films was achieved to study the growth dynamics and the effect on the magnetic anisotropy (MA). High-resolution X-ray diffraction and scanning transmission electron microscopy studies indicate the crystal structures of PBCO thin films are highly oriented with three variants, i.e., <100>(013) grains tilted around ±18° away from [00l] direction along a or b axis, <110>(001) domains rotated 45° along c axis, and common cube-on-cube <100>(001) epitaxy. The MA transformation to isotropic and an anomalous anisotropic magnetoresistance were observed in the films with the mosaic-patterned nanostructures. These evidences not only highlight the correlation between nanostructures and physical properties in perovskite systems, but also lay out the new avenues to manipulate the MA through controlling the preferred oriented nanostructures, which paves the way to create future nanoelectronics and spintronic devices via nanostructure design.

Laboratory time-resolved X-ray diffractometry for in situ studies of crystalline materials under uniaxial compression and vibration

A novel laboratory diffractometer for time-resolved high-resolution X-ray diffraction studies of reversible and irreversible processes in crystalline materials under uniaxial compression and vibration is described. Temporal resolution up to milliseconds for double-crystal and up to tens of seconds for triple-crystal diffraction experiments was achieved with a single adaptive bending X-ray optics element. Design solutions and techniques for applying and controlling uniaxial compression and vibration for in situ time-resolved studies are described. Results are presented for various static and dynamic load experiments, controlled by a system based on the TANGO Controls framework. Rocking curves of paratellurite (TeO2) under quasi-static compression and lithium fluoride (LiF) under ultrasonic vibration were measured with temporal resolution. Reciprocal-space maps of LiF under static compression and quartz (SiO2) under ultrasonic vibration were collected.

Coexisting Z-type charge and bond order in metallic NaRu2O4

How particular bonds form in quantum materials has been a long-standing puzzle. Two key concepts dealing with charge degrees of freedom are dimerization (forming metal-metal bonds) and charge ordering. Since the 1930s, these two concepts have been frequently invoked to explain numerous exciting quantum materials, typically insulators. Here we report dimerization and charge ordering within the dimers coexisting in metallic NaRu2O4. By combining high-resolution x-ray diffraction studies and theoretical calculations, we demonstrate that this unique phenomenon occurs through a new type of bonding, which we call Z-type ordering. The low-temperature superstructure has strong dimerization in legs of zigzag ladders, with short dimers in legs connected by short zigzag bonds, forming Z-shape clusters: simultaneously, site-centered charge ordering also appears. Our results demonstrate the yet unknown flexibility of quantum materials with the intricate interplay among orbital, charge, and lattice degrees of freedom.

Structural, electrical, and luminescence properties of (0001) ZnO epitaxial layers grown on c-GaN/sapphire templates by pulsed laser deposition technique

A systematic study of growth, structural, electrical, and luminescence properties of zinc oxide (ZnO) layers grown on c-oriented GaN/sapphire templates by the pulsed laser deposition technique is carried out. A thorough high-resolution x-ray diffraction study reveals that c-ZnO films with high crystalline quality can be grown under certain growth conditions. Screw and edge dislocation densities in these films are found to be as low as 7×108 and 3×1010cm−2, respectively. All layers are found to be unintentionally n-type with ∼1019cm−3 electron concentration and mobility as high as ∼50 cm2 V−1 s−1. Temperature and excitation intensity dependent photoluminescence (PL) studies as functions of the growth conditions are carried out to identify the transition processes behind various luminescence features found in these samples. At low temperatures, PL spectra are marked by sharp neutral donor bound excitonic transitions, their phonon replicas, and two broad luminescence bands at 2.2 and 2.9 eV. These broad bands are attributed to transitions from the (2+/0) oxygen vacancy (VO) and (2+/+/0) zinc-interstitial (Zni) levels, respectively, to the valence band. Thermal energy needed to depopulate these defects is found to be 11 and 385 meV, respectively, for the (2+/0) VO and (2+/+/0) Zni levels. Low temperature PL spectra for the samples grown with relatively high oxygen pressures are featured by the Zn-vacancy (VZn) related neutral acceptor bound excitonic transition, its phonon replicas, and a broad band at 2.75 eV. This band diminishes with increasing temperature and, instead, another broad feature appears at ∼2.1 eV. Our study attributes the 2.75 eV band to transition from the conduction band to (0/−) VZn levels and the 2.1 eV feature to the transition between (−/2−) VZn levels and the valence band. It has been found that all the defect related features can be minimized by adjusting the growth conditions.

Reduction in electrical resistivity of bismuth selenide single crystal via Sn and Te co-doping

The structural and thermoelectric transport properties of melt-grown Bi2Se3 single crystals are systematically investigated with the co-doping of Sn and Te in the temperature range 10–400 K. The powder X-ray diffraction and high-resolution X-ray diffraction studies confirm the hexagonal crystal structure with R3‾m space group. Images of the field emission scanning electron microscopy have shown crack-free smooth surface morphological features. Energy dispersive analysis of X-ray authorizes the chemical composition of elements in the samples. The degenerate semiconducting nature is observed in the entire series of samples with 6.8 times reduction in electrical resistivity for (Bi0.96Sn0.04)2Se2.7Te0.3 compared to the pristine Bi2Se3. The maximum ZT value of ∼0.32 is obtained for Bi2Se2.7Te0.3 single crystal at 400 K, about 7.4 times larger than that of Bi2Se3.

Systematic optical study of high-x InxGa1-xAs/InP structures for infrared photodetector applications

Optical and structural properties in high-x InxGa1-xAs (x > 0.65) samples with varying indium concentration grown on InP (100) substrate are reported. By increasing the indium fraction, it was found by the high-resolution X-ray diffraction (HR-XRD) study that the dislocation density in the InxGa1-xAs epitaxial layer significantly increased, and the surface quality deteriorated remarkably. Photoreflectance (PR) spectra show the presence of Franz-Keldysh Oscillations (FKOs) features above the InxGa1-xAs energy bandgap. The strain-induced electric field is then estimated directly from the FKOs periods. Temperature-dependent photoluminescence (TDPL) measurements from 10 K to 300 K showed carrier locations (S-shape). This abnormal behavior is due to the dislocation density associated with fluctuations in the indium concentration. A quasi-stationary rate equation model for the temperature-dependent luminescence spectra of the localized state material system is proposed to interpret the band gap emission process quantitatively. Low-temperature (10 K) time-resolved PL measurements show the increase of lifetime with increasing the indium concentration. Yet, the addition of only 1.7% of indium concentration results in a strong enhancement of PL lifetime by ∼ 80%.All these results reveal a more precise picture of the localization and recombination mechanisms of photogenerated carriers in the InGaAs layer, which could be the crucial factors in controlling the performance of high indium content InGaAs SWIR detector.

Investigation on thermo-physical properties of L-valinium picrate single crystal for industrial applications

Good quality L-valinium picrate single crystal was grown by slow evaporation technique. The lattice parameters of the crystal were measured by single crystal X-ray diffraction analysis. The High resolution X-ray diffraction study reveals good crystalline perfection of the grown crystals. The UV–Visible study reveals the transparency of the crystal in the entire visible region and the cut off wavelength has been found to be 462 nm. The thermal diffusivity and specific heat capacity were experimentally measured using photoacoustic technique and standard DSC technique, respectively. The thermo physical properties such as thermal conductivity, thermal diffusivity, specific heat capacity, volumetric specific heat capacity, and thermal effusivity of LVP are reported for the first time at ambient temperature.