Study Of Temperature Dependence Research Articles

Indirect Formation of Peptide Bonds as a Prelude to Ribosomal Transpeptidation.

The catalytic competency of the ribosome in extant protein biosynthesis is thought to arise primarily from two sources: an ability to precisely juxtapose the termini of two key substrates─3'-aminoacyl and N-acyl-aminoacyl tRNAs─and an ability to ease direct transpeptidation by their desolvation and encapsulation. In the absence of ribosomal, or enzymatic, protection, however, these activated alkyl esters undergo efficient hydrolysis, while significant entropic barriers serve to hamper their intermolecular cross-aminolysis in bulk water. Given that the spontaneous emergence of a catalyst of comparable size and sophistication to the ribosome in a prebiotic RNA world would appear implausible, it is thus natural to ask how appreciable peptide formation could have occurred with such substrates in bulk water without the aid of advanced ribozymatic catalysis. Using a combination of fluorine-tagged aminoacyl adenylate esters, in situ monitoring by 19F{1H} NMR spectroscopy, analytical deconvolution of kinetics, pH-rate profile analysis, and temperature-dependence studies, we here explore the mechanistic landscape of indirect amidation, via transesterification and O-to-N rearrangement, as a highly efficient, alternative manifold for transpeptidation that may have served as a prelude to ribosomal peptide synthesis. Our results suggest a potentially overlooked role for those amino acids implicated by the cyanosulfidic reaction network with hydroxyl side chains (Ser and Thr), and they also help to resolve some outstanding ambiguities in the broader literature regarding studies of similar systems (e.g., aminolyzes with Tris buffer). The evolutionary implications of this mode of peptide synthesis and the involvement of a very specific subset of amino acids are discussed.

Solution-processed tungsten diselenide as an inorganic hole transport material for moisture-stable perovskite solar cells in the n-i-p architecture

Some of the obstacles to the commercialization of perovskite solar cells (PSCs) are their long-term moisture stability and material cost of the constituent layers, such as the commonly used spiro-OMeTAD hole transport layer (HTL). Replacing the spiro-OMeTAD with low-cost inorganic hole transport materials (HTMs) are important to further elevate the attractiveness of PSCs for commercialization. Perovskite-compatible, solution-exfoliated two-dimensional (2D) transition metal dichalcogenides (TMDCs) are being considered as viable candidates for inorganic HTMs. We consider one such TMDC, WSe2 which was chemically exfoliated using dichlorobenzene (DCB), a perovskite-compatible solvent, as it was integrated with triple cation perovskite absorbers within the solar cell stack. The WSe2 HTL required heat treatment processes to be maintained below 100 °C in order to preserve the integrity of the underlying perovskite; despite this lower temperature post treatment process, the structural morphology of the film revealed its dense and pinhole-free nature. Temperature-dependent transport studies conducted on the WSe2 film provided evidence of its semiconducting character and its ability to extract holes well from the underlying triple-cation Cs0.05FA0.79MA0.16PbI2.45Br0.55 absorber. The inorganic HTL offered better environmental stability in moisture-rich environments of up to 60 % relative humidity, in comparison to spiro-OMeTAD HTL-based devices which degraded faster as a result of pinholes.

Enhancing Hole Transport and Autonomous Healing Properties of Supramolecular Columns in Unsymmetrical Discotics.

Designing smart autonomous healing soft materials is crucial to attaining cost-efficiency and optimal performance in organic semiconductors. In this context, we design an unsymmetrical thiophene-fused phenazine (TFP)-based discotic liquid crystal (DLC) with the goal of creating an active organic semiconductor that encompasses favorable attributes, such as polarizability, mobility, and processability. Aligned with our objective, we successfully synthesized two unsymmetrical TFP core-based DLCs by linking alkyl chains of variable lengths at the periphery through a coupling reaction. These DLCs show room temperature columnar oblique (Colob) mesophase as evident from temperature-dependent studies employing polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS). We performed space charge-limited current (SCLC) techniques to evaluate the hole mobility of TFP-based DLCs and found that they have high hole mobility (∼10-3 cm2/V s). Additionally, the film morphology and its self-healing nature have been examined using atomic force microscopy (AFM) and stress relaxation test. One of the unsymmetrical DLCs exhibited an ability to relax stress over time while maintaining a constant strain (up to 1-3%). The rational design of these unsymmetrical discotics, exhibiting reduced threshold voltage (as confirmed by conductivity studies) highlights their possible potential in various organic semiconductor devices.

The solid solutions RETi2Al20−x Ga x (0 ≤ x ≤ 10) with RE = Eu, Gd, Tb, Dy and Yb − first gallides with CeCr2Al20-type structure

Abstract The CeCr2Al20-type aluminides RETi2Al20 (RE = Eu, Gd, Tb, Dy and Yb), space group F d 3 ‾ m $Fd\overline{3}m$ , show the formation of solid solutions RETi2Al20−x Ga x with gallium in the ranges 0 ≤ x ≤ 10. Polycrystalline samples were prepared from the elements in alumina crucibles or directly via arc-melting followed by annealing in order to increase crystallinity. The structures of six single crystals were refined from single crystal X-ray diffractometer data for determining the precise occupancy parameters of the aluminum and gallium atoms. The solubility limit of gallium was found at around x ≈ 10. The RETi2Al20−x Ga x structures show a MgCu2-related substructure of the rare earth and titanium atoms. The Al/Ga atoms then form Frank-Kasper type polyhedra around the RE and Ti atoms, i. e., RE@(Al/Ga)16 and Ti@(Al/Ga12). These are the basic building units of the RETi2Al20−x Ga x structures. Temperature-dependent magnetic susceptibility studies show Pauli paramagnetic behavior for the YbTi2Al10Ga10 sample, i. e., a stable divalent ytterbium ground state.

CO2 selectivity and adsorption performance of K2CO3-modified zeolite: a temperature-dependent study.

High-performing zeolite materials for carbon dioxide capture are promising for applications such as flue gas CO2 capture. Potassium carbonate-loaded zeolites can offer a plethora of benefits. In this work, for the first time, zeolite-Y impregnated with K2CO3 was studied as a gas adsorbent (CO2, CH4, and N2) and characterized using TGA (thermogravimetric analyzer), XRD, BET, FTIR, FETEM (Field-Emission Transmission Electron Microscope), and XPS. The effect of carbonate loading, temperature, and pressure was particularly targeted and assessed. Accordingly, for a variation in K2CO3 loading from 5 to 15 wt.%, the CO2 adsorption capacity reduced from 3.61 to 1.73mmolg-1 in the synthesized adsorbents. Among all the cases, KYZC10 exhibited very good cyclic adsorption-desorption performance and thermal stability. Further equilibrium modeling studies indicate that the stable and optimally K2CO3-loaded adsorbent (KYZC10) demonstrates effective adsorption isotherm behavior, making it suitable for different temperature variation processes in commercial carbon dioxide capture applications. The KYZC10 adsorbent's stable performance at varying temperatures contributes to its enhanced economic feasibility. This study also used the ideal adsorbed solution theory (IAST) to predict CO2 selectivity over other gases (CH4 and N2).

Investigation of resistive switching behavior driven by active and passive electrodes in MoO2–MoS2 core shell nanowire memristors

Memristive devices based on layered materials have the potential to enable low power electronics with ultra-fast operations toward the development of next generation memory and computing technologies. Memristor performance and switching behavior crucially depend on the switching matrix and on the type of electrodes used. In this work, we investigate the effect of different electrodes in 1D MoO2–MoS2 core shell nanowire memristors by highlighting their role in achieving distinct switching behavior. Analog and digital resistive switching are realized with carbon based passive (multi-layer graphene and multiwall carbon nanotube) and 3D active metal (silver and nickel) electrodes, respectively. Temperature dependent electrical transport studies of the conducting filament down to cryogenic temperatures reveal its semiconducting and metallic nature for passive and active top electrodes, respectively. These investigations shed light on the physics of the filament formation and provide a knob to design and develop the memristors with specific switching characteristics for desired end uses.

Unveiling differential interaction pattern for iminium and alkanolamine forms of Sanguinarine with β-Lactoglobulin protein

A comparative study on the interaction of two tautomeric forms of sanguinarine (SANG), an alkaloid with therapeutic properties, with β-lactoglobulin (β-LG) protein was explored using spectroscopic and computational methods. The spectroscopic study reveals a high binding affinity for alkanolamine to monomeric β-LG (at pH = 9) as compared to iminium to dimeric β-LG (at pH = 6.2). Temperature dependent fluorescence study provides thermodynamic parameters for the binding process. Circular dichroism spectra showed changes in the secondary structure of the protein with major conformational transition from α-helix to β-sheets. Molecular docking and MD simulation validate the stable protein-drug complex during a 200 ns simulation period. All results clearly depict the differential interactions of two forms of SANG with β-LG protein. Overall, the characterization of SANG binding interactions with the whey milk protein provides valuable insights for pharmacological research and design of novel drug carriers based on β-LG protein.

Reusable nontoxic pyrimidine‐based oleogelators: Phase selectivity and nanostructured structuring

AbstractOver the last few decades, scientists have been working hard to produce edible structural agents those can be used in food, cosmetics, agriculture, pharmaceuticals, and biotechnology. The supramolecular assembly of simple amphiphiles in presence of edible oil is the most ideal system for this purpose because the system has no harmful health consequences. We have attempted to address the aforementioned implications in this article by synthesizing a novel class of structuring agents 2‐alkyl amino pyrimidine‐4‐carboxylic acid amphiphiles named 2‐decylamino‐pyrimidine‐4‐carboxylic acid (DPCA), 2‐dodecylamino‐ pyrimidine‐4‐carboxylic acid (DDPCA) and 2‐tetradecylamino‐pyrimidine‐4‐carboxylic acid (TDPCA), using simple procedure. To our delight, the prepared amphiphiles self‐assemble to a gel matrix in various vegetable oils and mineral oils. Microscopic analyses were used to investigate the nanostructured morphology of molecular gels. Rheological studies revealed that oleogels are mechanically processable and viscoelastic. Temperature dependent and concentration dependent proton nuclear magnetic resonance (1H‐NMR) studies were performed to analyze the hydrogen bonding and π–π interactions. The study discovered that gelators act as reusable phase selective gelators (PSG) of oil in water–oil mixture. The (3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5 diphenyl tetrazolium bromide) (MTT) assay has proven that the synthetic oleogelators are nontoxic.

Microwave assisted synthesis of ErxYbyCa1-x-yMoO4 nano-phosphor for efficient temperature sensing and catalytic applications

Here, Er/Yb Co-doped CaMoO4 materials (ErxYbyCa1−x−yMoO4 NPs where x = 0, 0.01 and y = 0, 0.05, 0.10, 0.15, 0.20) were prepared by microwave-assisted method and its pure-tetragonal structure were confirmed by X-ray diffraction spectra (XRD), Rietveld-refinement and Raman-vibrational spectra. The transmission-electron microscopy (TEM) study indicates the formation of nearly spherical shaped nanomaterial with average size of ~ 15 nm. Additionally, absorption and emission properties were studied by UV–Visible–NIR and photoluminescence (PL) spectrometer. The UV–Visible–NIR spectra attribute absorption of Er3+ ion in visible region (380–700 nm) and absorption of Yb3+ ion in near-infrared region (700–1400 nm). Moreover, PL up-conversion spectra of the sample recorded under excitation wavelength 980 nm. The PL peaks were observed at 530, 544–552, and 656–670 nm. Prominent PL-intensity was observed for Er0.01Yb0.15Ca0.84MoO4 phosphor. Temperature dependent PL study reveals that present phosphor is robust phosphor for temperature sensor. In addition, Er3+/Yb3+ doped CaMoO4 nanomaterials exhibited excellent activity and selectivity in the aerial oxidation of benzoin over benzyl under oxidant-free reaction conditions. The synergistic effect Er3+/Yb3+ co-doing in CaMoO4 matrix was observed, where only CaMoO4 material found to be inactive towards above oxidation reaction. Moreover, the oxidation of primary benzyl-alcohols was furnished in presence of tertiary butyl hydroperoxideas oxidant.

Uncovering upconversion photoluminescence in layered PbI2 above room temperature.

As a van der Waals (vdW) layered semiconductor material, lead iodide (PbI2) possessing a direct bandgap with strong photoluminescence emission in visible range has gained wide attention in applications of photonic and optoelectronic devices. Here, upconversion photoluminescence (UPL) in exfoliated PbI2 flakes is demonstrated at room temperature and elevated temperatures. The linear power dependence of UPL emission with 532nm excitation suggests the one-photon involved multiphonon-assisted UPL emission process, which is revealed by the temperature-dependent UPL emission measurement. Meanwhile, the nonlinear power dependence of UPL emission with 561nm excitation indicates the transition of UPL emission mechanism from linear to nonlinear regime, and the temperature-dependent UPL emission study further shows that the upconversion is contributed by both the multiphonon-assisted UPL process and the two-photon absorption induced PL process. This study will provide an insight to the understanding of photon upconversion in vdW layered semiconductors and advancing applications in temperature-controlled photon upconversion, tunable photonics, photodetection and imaging.

Comparative analysis of machine learning techniques in predicting dielectric behavior of ternary chalcogenide thin films

Abstract The current research introduces a comparative analysis of the dielectric behavior exhibited by ternary chalcogenide thin films, including both experimental data and machine learning techniques. The study of temperature and frequency dependencies of dielectric parameters is crucial for assessing material losses, particularly focusing on the low-frequency range where dielectric dispersion occurs. The experimental results on the frequency (100–1000000 Hz)and the temperature(303–393 K) influences on the dielectric (constant ( ε 1 ) and loss ( ε 2 )) of A s 4 G e 24 T e 72 composition in thin film form have been discussed. Results demonstrate that ε 1 exhibits an increasing trend with temperature, attributed to heightened orientation polarization as dipoles gain mobility with elevated thermal energy. Conversely, ε 1 declines with rising frequency, reflecting diverse different polarization mechanisms. Understanding these behaviors is important for material characterization and applications in fields like electronics and solar cells. A comparative analysis of the dielectric behavior exhibited by ternary chalcogenide thin films, including both experimental data and machine learning techniques. Through the experimental approach, the dielectric properties of the films are investigated. Additionally, the study employs a range of machine learning algorithms, including Artificial Neural Networks (ANN), Adaptive Neuro-Fuzzy Inference Systems (ANFIS), Genetic Programming (GP), hybrid techniques ANFIS-GA, and ANFIS-PSO, to model and predict the dielectric behavior with remarkable accuracy. The paper presents a comparison between the performance of the proposed machine learning models, highlighting their strengths and limitations in capturing the complex dielectric phenomena observed in the ternary chalcogenide thin films. This comparative study not only provides valuable insights into the dielectric properties of these materials but also demonstrates the efficacy of machine learning in understanding and predicting their behavior, paving the way for further advancements in materials science and device development.

Molecular Design and Synthetic Approaches for the Realization of Multichannel Radiative Decay Pathways in Gold(III) Complexes and Their Applications in Organic Light-Emitting Devices.

A unique class of tridentate diaryltriazine ligand-containing gold(III) complexes with thermally activated delayed fluorescence (TADF) and/or thermally stimulated delayed phosphorescence (TSDP) properties has been designed and synthesized. With a simple structural modification on the coordination of carbazole moiety in the monodentate ligand, a large spectral shift of ∼160 nm (ca. 4900 cm-1) spanning from sky blue to red emissions has been demonstrated in solid-state thin films. Three-state or four-state models have been employed in fitting the emission lifetimes of the gold(III) complexes at various temperatures. The findings clearly indicate the presence of three emitting states, S1, T1, and T1', suggesting the coexistence of TADF, phosphorescence, and TSDP. Notably, a minor structural change in the donor moiety between phenylcarbazolyl and diphenylaminoaryl has been demonstrated to turn on/off the TSDP, resulting in TADF-TSDP-phosphorescence or TADF-phosphorescence emitters. The TADF and/or TSDP properties have also been supported by temperature-dependent ultrafast transient absorption studies, with the direct observation of reverse intersystem crossing (RISC) and reverse internal conversion (RIC) and the determination of the activation parameters and excited state dynamics. Solution-processed and vacuum-deposited organic light-emitting devices (OLEDs) have been prepared, in which sky blue emitting devices based on 5 exhibit an operational lifetime LT70 ∼ 5 times longer than the previously reported sky blue emitting analogue that shows only TSDP property. These results have provided valuable insights into the manipulation of the excited states via rational molecular design toward the realization of gold(III)-based TSDP and/or TADF materials with multiple radiative decay pathways that show enhanced radiative decay rate constants (kr) for practical OLED applications.

Exploring Thermal Stability, Vibrational Properties, and Biological Assessments of Dichloro(l-histidine)copper(II): A Combined Theoretical and Experimental Study.

Dichloro(l-histidine)copper(II) crystal ([Cu(l-His)Cl2] complex) was obtained by the slow evaporation method and characterized concerning its thermal stability, phase transformations, and electronic and vibrational properties. X-ray diffraction (XRPD) confirmed that this complex crystallizes with an orthorhombic structure (P212121 space group). Thermal analyses (TG and DTA) demonstrate stability from ambient temperature up to 460 K, followed by a phase transition from the orthorhombic structure to the amorphous form around 465 K, as confirmed by temperature-dependent XRPD studies. The active modes in Fourier transform infrared (FT-IR) and Raman spectroscopy spectra were suitably assigned via density functional theory (DFT) calculations. Additionally, Hirshfeld surface analysis uncovered the prominence of Cl···H, O···H, and H···H interactions as the primary intermolecular forces within the crystal structure. The antimicrobial activity of the [Cu(l-His)Cl2] complex was investigated, demonstrating significant efficacy against Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Pseudomonas aeruginosa), and fungi (Candida albicans). The minimum inhibitory concentration and cell viability tests showed that the complex inhibits the growth of S. aureus bacteria at a concentration of 1.5 μM without causing damage to the human cell line. The pharmacokinetic parameters corroborate the other tested parameters and highlight the [Cu(l-His)Cl2] complex as a promising alternative for future clinical trials and medicinal applications. The alignment of the pharmacokinetic parameters with other tested criteria highlights the potential of the [Cu(l-His)Cl2] complex as a promising candidate for future clinical studies.

Effects of Ionic Liquids on the Nucleofugality of Dimethyl Sulfide.

The nucleofugality of dimethyl sulfide was measured in solvent mixtures containing ionic liquids. The first-order rate constants of the solvolysis of sulfonium salts were determined in mixtures containing different proportions of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide in ethanol, representing the first report on the solvolysis of a charged species in an ionic liquid. Temperature-dependent kinetic studies allowed determination of activation parameters and rationalization of observed solvent effects in different ionic liquid mixtures. From the solvolysis data, the nucleofugality of dimethyl sulfide in different proportions of this ionic liquid in ethanol was determined. Further, the nucleofugality of dimethyl sulfide was determined in mixtures containing high proportions of each of seven other ionic liquids in ethanol. These data allowed quantification of the effects of varying both the amount of ionic liquid present and on changing the components of the ionic liquid on the nucleofugality of dimethyl sulfide. The ionic liquid mixtures were shown to affect the nucleofugality of this nucleofuge in a different manner to the previously studied monatomic charged nucleofuges, owing to different microscopic interactions in solution. This work highlighted the necessity of considering electrofuges with an appropriate range of electrofugality values along with the importance of the nucleofuge-specific sensitivity parameter.

Tailored Permeation Through ≈1 nm Thick Carbon Nanomembranes by Subtle Changes in Their Molecular Design.

Due to their nanoscale thickness (≈1 nm) and exceptional selectivity for permeation of gases, nanomembranes made of 2D materials possess high potential for energy-efficient nanofiltration applications. In this respect, organic carbon nanomembranes (CNMs), synthesized via electron irradiation-induced crosslinking of aromatic self-assembled monolayers (SAMs), are particularly attractive, as their structure can be flexibly tuned by choice of molecular precursors. However, tailored permeation of CNMs, defined by their molecular design, has not been yet demonstrated. In this work, it is shown that the permeation of helium (He), deuterium (D2) and heavy water (D2O) for CNMs synthesized from biphenyl-based SAMs on silver (C6H5-C6H4-(CH2)n-COO/Ag, n = 2-6) can be tuned by orders of magnitude by changing the structure of the molecular precursors by just a single methylene unit. The selectivity in permeation of D2O/D2 with an unprecedented value of 200000 can be achieved in this way. The temperature-dependent study reveals a clear correlation between the molecular design and the permeation mechanisms facilitating therewith tailored synthesis of molecular 2D materials for separation technologies.

Impact of the Ge-Si interfacial barrier on the temperature-dependent performance of PureGaB Ge-on-Si p + n photodiodes

A temperature-dependent study of the near-infrared (NIR) responsivity of Ge-on-Si photodiodes is presented. The diodes, formed as n-Ge islands within oxide windows on n-Si and capped with Ga and B layers (PureGaB), exhibit low dark current of ∼2 × 10−13 A/µm2 and broadband responsivity. Temperature-dependent measurements reveal an inherent potential barrier at the low-doped n-Ge on the n-Si heterointerface. This leads to a decrease in responsivity with decreasing temperatures for wavelengths above 1100 nm. The Al-migration process along the Ge-Si interface, associated with the sidewall passivation and found to be a means of reducing dark current, increases the barrier height. Irrespective of the barrier height, room-temperature responsivity is fully recovered by applying a reverse bias to lower the interface barrier. In the devices with the highest barrier, the responsivity at 1310 nm increased from 4.8 to 164 mA/W, at 0 V and 18 V reverse bias, respectively. An additional increase in maximum responsivity at 1550 nm is attributed to Al-sidewall passivation leading to a measured responsivity of 126.4 mA/W at 18 V reverse bias.

Polaron assisted hopping mechanism in microwave processed Nd doped second layered aurivillius SrBi2Nb2O9 ceramics

The polycrystalline Sr0.8Sn0.2Bi1.75Nd0.25Nb2O9 (NdSBN) was synthesized using the green synthesis microwave sintering method, which significantly reduced the processing parameters of the NdSBN ceramics. Orthorhombic crystal structure with A21am symmetry was revealed by Rietveld refinement study, whereas the doping-induced strain and crystallite size was studied using the Williamson Hall method. Crossectional SEM micrographs confirm the plate-like structure, with an average grain size of 273.7 nm. A diffuse type of phase transition was observed at 345 °C, which usually arises due to compositional fluctuations and mobile oxygen vacancies; further, the diffusiveness of the NdSBN was studied using Uchino and Nomura function, a modified version of Curie-Weiss law (CW). The frequency and temperature-dependent dielectric study of NdSBN ceramics display a Maxwell-Wagner relaxation with a high loss in a low frequency regime, possibly due to the presence of leakage current in the solid solution. Frequency dependent AC conductivity obeys Jonscher's power law, whereas DC conductivity supports polaron assisted hopping in NdSBN composition with dual activation energies of 0.55 eV and 0.75 eV, which correspond to electrons and ions, respectively. The non-Debye type relaxation mechanism in conjunction with negative temperature coefficient of resistance (NTCR) behavior was demonstrated by temperature dependent impedance spectroscopy, while modulus spectroscopy confirmed the multiple relaxation processes in NdSBN ceramics.

Optical characteristics, Judd-Ofelt analysis of enhanced luminescence by flux in thermally stable, novel Eu3+- doped BaZr(PO4)2 phosphor for indoor lighting applications

A series of novel single phased Eu3+ doped BaZr(PO4)2 phosphor were synthesized employing simple solid-state reaction route and studied the influence of different chlorides as fluxes (NH4Cl, KCl, LiCl and NaCl) on structural and photoluminescence properties. The structural characterization reveals pure phase formation of the as prepared phosphors with monoclinic crystal structure. The photoluminescence (PL) spectra recorded under 392 nm excitation depicts intense emission at 612 nm. Further, the concentration of Eu3+ ion was well tuned by carefully studying the PL spectra and the optimised amount of Eu3+ ion in BaZr(PO4)2 is found to be 3.0 mol%. The luminescence properties of phosphor with added aforementioned fluxes were also studied in detail. NH4Cl was found to be the best among all the fluxes taken and the photoluminescence intensity of phosphor gets enhanced by 1.43 times of without flux. The Judd-Ofelt theory was employed for determination of spectral parameters from photoluminescent emission spectra. The temperature dependent photoluminescent studies establishes stability of phosphor emission at operating temperatures. The CIE coordinates were evaluated that confirms the pure red emission under n-UV excitation. All the studies indicate the potential of the said phosphor in phosphor converted white light emitting diodes as red emitter and indoor lighting.

Dynamics of magnetic inhomogeneity in La2CoMnO6 films probed by Raman spectroscopy

We report the dynamic effects of magnetic inhomogeneity on the temperature evolution of the Raman modes in polycrystalline La2CoMnO6 (LCMO) films. The LCMO films were obtained via chemical solution deposition and annealed at different temperatures, 700, 800 and 900 °C. Temperature-dependent Raman spectroscopic studies uncover anomalous phonon energy behaviors, associated with strong spin-phonon couplings revealed even at ambient conditions. This effect, which is observed to occur well above ferromagnetic ordering temperature is ascribed to short-range Mn4+/Co2+ ferromagnetic clusters. Moreover, our study has shown that spin-phonon coupling strength is governed by competing antiferromagnetic (AFM) and ferromagnetic (FM) interactions. These results significantly enhance the understanding of the complex spin-phonon coupling mechanism to provide insights into magnetic inhomogeneity in systems with two or more magnetic sublattices. These findings suggest the presence of similar effects in other double perovskites within the RE2CoMnO6 (RE = rare earths) family, which exhibit analogous magnetic sublattice and order–disorder defects.

Temperature-dependent hydrothermal processing of WS2 nanorods with controlled growth morphology, crystallography and optical properties

WS2 nanorods with uniform size-distribution of width 120 nm and length 600–950 nm were successfully processed at 230 °C by reliable and cost-effective hydrothermal method. Two more temperatures (±10 °C) were employed to understand its influence on structural- and optical-properties. Consequences achieved from crystallography and spectroscopy analyses suggest that formation of hexagonal-phase of crystalline WS2 with direct allowed band-gap values in upward manner as temperature increased. In light of temperature-dependent studies achieved from experimental evidences, plausible growth-mechanism of WS2 nanorods was proposed. It will provide potential reference for future studies in both basic- and applied-WS2 research.