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We present comprehensive temperature dependent Raman measurements for chemical vapor deposition grown horizontally aligned layered MoS2 in a temperature range of 4–330 K under a resonance condition. Our analysis of temperature dependent phonon frequency shift and linewidth suggests a finite role of three and four phonon anharmonic effect. We observe Davydov splitting of the out-of-plane (A1g) and in-plane () modes for both three layer (3L) and few layer (FL) systems. The number of Davydov splitting components are found more in FL compared to 3L MoS2, which suggests that it increases with an increasing number of layers. Further, Davydov splitting is analyzed as a function of temperature. Temperature evaluation of the Raman spectra shows that the Davydov splitting, especially for A1g mode, is very strong and well resolved at low temperature. We observe that A1g mode shows the splitting at low temperature, while mode is split even at room temperature, which suggests a prominent role of A1g mode in the interlayer interaction at low temperature. Further, an almost 60-fold increase in the intensity of the phonon modes at low temperature clearly shows the temperature dependent tuning of the resonance effect. [ABSTRACT FROM AUTHOR]

Surface roughness is one of the critical parameters that affect the component performance during its working life. To develop any process to its full potential, it is necessary to understand the physics of that process. Abrasive flow finishing (AFF) is one of the advanced finishing processes. In the current research work, an effort is made to understand physics and mechanism of surface roughness improvement during the AFF process. This research paper is divided into two sections. Firstly, the amount of finishing stresses and forces generated during the finishing of microholes fabricated on surgical stainless steel (316L) workpieces are computed by using the finite element method. Finishing stresses are generated in the viscoelastic medium. So, to compute finishing stresses, finite element analysis of the viscoelastic medium is carried out by incorporating its experimentally measured rheological properties. Finishing stresses are calculated along the circumferential direction of the microhole. Later, at the same workpiece surface location, simulated and experimentally measured surface roughness value are compared. Secondly, a new simulation model is proposed to predict the surface roughness on the microhole wall surface for various AFF input parameters. Maximum percentage change in surface roughness error of 8% is observed between simulated and experimental results after AFF process. [ABSTRACT FROM AUTHOR]

Abrasive flow finishing (AFF) is one of the advanced finishing processes used mainly for finishing of complex surface features. Nano finishing of aluminum alloys is difficult using conventional finishing processes because of its soft nature. So, in this work, aluminum alloys are finished using AFF process. Since the finishing is carried out using polymer rheological abrasive medium (medium), the finishing forces on aluminum alloy workpieces are too low compared to conventional finishing processes. Thus, this process generates nano surface roughness on aluminum alloy. By using the theoretical model, change in surface roughness (ΔRa) with respect to various AFF input parameters is studied. A new simulation model is proposed in this paper to predict the finishing forces and ΔRa during AFF process. Modeling of finishing forces generated during the AFF process is carried out using ansys polyflow. These forces are used as input in the simulation model to predict ΔRa. Medium rheology decides the magnitude of the generated finishing forces in AFF process. Therefore, to predict the forces accurately, rheological properties of the medium are measured experimentally and used as input during modeling. Further, to make the simulation more realistic, abrasive particle bluntness with respect to extrusion pressure and number of strokes is considered. Because of considering these realistic conditions, simulation and experimental results are in better agreement compared to theoretical results. [ABSTRACT FROM AUTHOR]

2D MoS2 holds immense potential for electronic and optoelectronic applications due to its unique characteristics. However, the atomic-scale thickness of MoS2 hinders the optical absorbance, thereby limiting its photodetection capability. Vertically-aligned MoS2 (VA-MoS2) has an advantage of strong optical absorption and quick intra-layer transport, offering high speed operation. The coupling of plasmonic metal nanostructure with MoS2 can further enhance the lightâ€"matter interaction. Pt/Pd (as opposed to Ag/Au) are more promising to design next-generation nano-plasmonic devices due to their intense interband activity over a broad spectral range. Herein, we report Pt nanoparticle (NPs) enhanced broadband photoresponse in VA-MoS2. The optical absorbance of MoS2 is enhanced after the integration of Pt NPs, with a four-fold enhancement in photocurrent. The formation of Schottky junction at Pt-MoS2 interface inhibits electron transmission, suppressing the dark current and substantially reducing NEP. The plasmonic-enabled photodetector shows enhanced responsivity (432 A Wâˆ'1, 800 nm) and detectivity (1.85 × 1014 Jones, 5 V) with a low response time (87 ms/84 ms), attributed to faster carrier transport. Additionally, a theoretical approach is adopted to calculate wavelength-dependent responsivity, which matches well with experimental results. These findings offer a facile approach to modulate the performance of next-generation optoelectronic devices for practical applications. [ABSTRACT FROM AUTHOR]

A 2D/3D heterostructure of MoS 2 /Ga 2 O 3 exhibits excellent performance in broadband photodetection, demonstrating an impressively wide photo-response range spanning from UV-C to NIR, with high responsivity and fast response time. [Display omitted] • Band-alignment and charge carrier dynamics are studied at MoS 2 /a-Ga 2 O 3 heterointerface. • Broadband photoresponse from Deep UV to NIR. • The heterostructure photodetector exhibits an impressive responsivity of 171 A/W, which is over 300 times higher than that of a pristine MoS 2 photodetector. • MoS 2 /a-Ga 2 O 3 photodetector exhibits fast rise/fall time of 97/114 µs. • The photodetector demonstrates remarkable long-term stability and reproducibility in photoresponse. Recently, 2D materials have gained tremendous research interest due to their unique properties in electronics and optoelectronics. However, single 2D material-based photodetectors suffer from limitations such as narrow spectral sensitivity and slow response time due to bandgap restriction and difficulty in charge extraction. A heterojunction, which separates photo-excited electron-hole pairs and tunes absorption edge through appropriate selection of semiconductors with complementary bandgaps, is an effective strategy for broad spectral energy-conserving photodetection. This study presents a scalable 2D/3D heterostructure of MoS 2 /Ga 2 O 3 with outstanding UV-C to NIR broad spectral photoresponse. The MoS 2 /Ga 2 O 3 photodetector demonstrated a 315-fold increase in responsivity and EQE compared to pristine MoS 2 photodetector. The device showed highest responsivity and EQE of 171 AW−1 and 2.4 × 104 % respectively under 900 nm illumination at 5 V bias. The device also exhibits high detectivity (4.6 × 1013 Jones) and fast response time of 97 µs. Moreover, the device is highly stable and shows no performance degradation over time. The device behavior was investigated through energy band diagrams and charge carrier dynamics using photoelectron spectroscopy and Kelvin probe force microscopy to gain intrinsic physical insights. The demonstration of MoS 2 /Ga 2 O 3 as a high-performance broadband photodetector offers exciting opportunities for efficient optoelectronics and imaging applications. [ABSTRACT FROM AUTHOR]

Abstract Development of solid electrolytes with good lithium ion conductivity is one of the key pre-requisites of high performing rechargeable all-solid-state lithium batteries. In this work, NA-Super-Ionic-CONductor (NASICON)-type LiSnZr(PO 4) 3 ceramics fabricated via a sol-gel route were characterized using Synchrotron x-ray diffraction, Raman Spectroscopy, x-ray photoelectron spectroscopy (XPS) and complex impedance spectroscopy. Stabilization of high Li+ conducting rhombohedral (R 3 ¯ c) phase at room temperature was confirmed by the Rietveld refinement of synchrotron x-ray diffraction data. LiSnZr(PO 4) 3 sample sintered at 1000 °C exhibited an excellent room temperature bulk and total conductivity ∼ 0.1 mScm−1 and 1.45 × 10−5 Scm−1 with associated activation energies of ∼0.36 eV and ∼0.38 eV, respectively. Direct current polarization study confirmed the conductivity of LiSnZr(PO 4) 3 as predominantly ionic in nature. The role of inductive effect in improving the room temperature ionic conductivity by utilizing the electronegativity of counter-cations in NASICON framework is also discussed. Graphical abstract Image 1 Highlights • LiSnZr(PO 4) 3 was prepared via a sol-gel method. • Rhombohedral phase (R 3 ¯ c) achieved at synthesis temperature of 900 °C. • LiSnZr(PO 4) 3 exhibited excellent RT bulk ionic conductivity ∼ 0.1 mScm−1. • Signifies the role of inductive effect in facile Li+ conduction. [ABSTRACT FROM AUTHOR]

Abstract Structural, vibrational and dielectric properties of (Pb 1- x Bi x )(Ti 1- x Mn x )O 3 (PBTM) (0 ≤ x ≤ 0.50) polycrystalline ceramics have been examined as a function of temperature. Synchrotron-based powder x-ray diffraction was employed to confirm phase purity and crystal structures of the samples. Tetragonality ( c / a ratio) of the PBTM system increased to 1.066 from 1.064 for the compositions x = 0.12 for pure PbTiO 3 sample and decreased with further increase in x (≥0.18). The temperature of phase transition increased to a maximum of 773 K for the sample x = 0.09. The peak corresponding to the ferroelectric-paraelectric phase transition for x = 0.09 sample was accompanied by a change in crystal structure from tetragonal to cubic at ∼773 K, as confirmed by the temperature dependent XRD data. Unit cell volume was found to decrease with increase in temperature, indicating the existence of a negative coefficient of thermal expansion in all samples up to the temperature of phase transitions. The thermal coefficients were found to be −1.571 × 10−5/K, −2.44 × 10−5/K, and −0.50 × 10−5/K for x = 0, 0.06, and 0.09 samples, respectively. Raman spectra showed softening of the transverse optical phonon modes and their full width at half maxima (FWHM) increased with the increase in composition. Field-emission scanning electron microscope equipped with energy dispersive x-ray spectrometer (EDS) confirmed compositional homogeneity and dense-type microstructure. Highlights • (Pb 1- x Bi x )(Ti 1- x Mn x )O 3 (0 ≤ x ≤ 0.50) powders were synthesized using sol-gel method. • Tetragonal lattice strain was found to increase for samples with x ≤ 0.12. • Negative thermal expansion was observed in tetragonal phase for all samples. • Highest T C ≈ 773 K was observed for sample with x = 0.09. [ABSTRACT FROM AUTHOR]

Through the modifications in crystal structure and particle morphology introduced by Ti substitution, a faster Na-ion diffusion was achieved in P2-Na 0.70 Ni 0.20 Cu 0.15 Mn 0.65 O 2 , which significantly improved specific capacity and rate performance. [Display omitted] • Ti substitution increased the area of Na-ion conduction bottlenecks. • The aspect ratio of particles decreased from ∼8 to ∼1. • Na 0.70 Ni 0.20 Cu 0.15 Mn 0.575 Ti 0.075 O 2 showed a capacity of 127 mAh/g at 0.1C. • Excellent capacity retention of 97% was achieved after 300 cycles at 1C. In recent years, P2-type layered oxides have received considerable attention as potential cathodes for Na-ion batteries owing to their compositional diversity, good specific capacity, and cyclability. However, poor rate performance and low-capacity retention at high discharge rates have limited their use in commercial battery applications. This study aims to mitigate this issue by synthesizing a series of structurally engineered P2-type cathode materials, through Ti substitution, with high cyclability and improved rate performance. P2-type Na 0.70 Ni 0.20 Cu 0.15 Mn (0.65- x) Ti x O 2 were prepared through a sol–gel route and were characterized for their structural, electrical, and electrochemical properties In the Ti-substituted samples, the Rietveld refinement of XRD data revealed an increased size of the bottleneck area of the Na-O 6 prism planes, while the SEM images showed a decrease in the aspect ratio of hexagon-type morphology of particles which facilitates faster Na-ion conduction through the material. These changes in the crystal structure and particle morphology induced by Ti substitution have significantly improved electrical and electrochemical performance compared to the parent material. The sample with x = 7.5% exhibited a specific capacity of 126 mAh/g at a discharge rate of 0.1C in the 2.00–4.25 V window, which was about 25% more than that of the undoped material. At a discharge rate of 1C, the specific capacity of Na 0.70 Ni 0.20 Cu 0.15 Mn 0.575 Ti 0.075 O 2 was 97 mAh/g compared to 74 mAh/g for Na 0.70 Ni 0.20 Cu 0.15 Mn 0.65 O 2 sample. Na 0.70 Ni 0.20 Cu 0.15 Mn (0.65- x) Ti x O 2 samples also exhibited excellent cyclability, with over 95% of original capacity retained after 300 cycles. Complex impedance measurements corroborated the improved Na-ion conductivity in Ti-doped samples and an associated increase in Na-ion transference number from 0.86 for the sample with x = 0 to 0.97 for the sample with x = 0.075. [ABSTRACT FROM AUTHOR]

Two dimensional chalcogenides and metal sulfide materials with their sensitive surfaces are promising and potential postulant for the purpose of chemical gas sensing as a consequence of extraordinary vast surface area to volume ratio and significant band gap. We demonstrate a highly selective and sensitive NO 2 gas sensor using vertically aligned 2D SnS 2 flakes, grown by a chemical vapor deposition method in controlled gas flow. The vertically aligned SnS 2 flakes were confirmed by scanning electron microscopy, Raman spectroscopy, and X-ray diffraction. The sensing behaviour of the vertical aligned structures was analyzed for various concentrations of NO 2 at different temperatures. The sensor exhibits high gas sensing response (ΔR/R%) of ~164 at 120 °C with 50 ppm of NO 2 gas, which is the highest response among the SnS 2 based reports. The device shows excellent sensing response at room temperature but poor recovery. The selectivity of the sensor was performed under different gas environments and found highly selective towards NO 2 gas, and the results are supported by electronic structure calculations. Based on experimental results and electronic structure calculations, a gas sensing mechanism is proposed. The result indicates that fabricated sensor can be used in air purification industries and in air monitoring. • Vertically aligned 2D SnS 2 flakes were grown by CVD in controlled gas flow. • Highly selective and sensitive NO 2 gas sensor was fabricated using vertically aligned 2D SnS 2 flakes. • The sensor exhibits high gas sensing response (ΔR/R%) of ~164 at 120 °C with 50 ppm of NO 2 gas. • The selectivity of the sensor is supported by electronic structure calculations. • The sensing mechanism responsible for the dramatically increased sensitivity was also discovered. [ABSTRACT FROM AUTHOR]

Two dimensional chalcogenides and metal sulfide materials with their sensitive surfaces are promising and potential postulant for the purpose of chemical gas sensing as a consequence of extraordinary vast surface area to volume ratio and significant band gap. We demonstrate a highly selective and sensitive NO 2 gas sensor using vertically aligned 2D SnS 2 flakes, grown by a chemical vapor deposition method in controlled gas flow. The vertically aligned SnS 2 flakes were confirmed by scanning electron microscopy, Raman spectroscopy, and X-ray diffraction. The sensing behaviour of the vertical aligned structures was analyzed for various concentrations of NO 2 at different temperatures. The sensor exhibits high gas sensing response (ΔR/R%) of ~164 at 120 °C with 50 ppm of NO 2 gas, which is the highest response among the SnS 2 based reports. The device shows excellent sensing response at room temperature but poor recovery. The selectivity of the sensor was performed under different gas environments and found highly selective towards NO 2 gas, and the results are supported by electronic structure calculations. Based on experimental results and electronic structure calculations, a gas sensing mechanism is proposed. The result indicates that fabricated sensor can be used in air purification industries and in air monitoring. • Vertically aligned 2D SnS 2 flakes were grown by CVD in controlled gas flow. • Highly selective and sensitive NO 2 gas sensor was fabricated using vertically aligned 2D SnS 2 flakes. • The sensor exhibits high gas sensing response (ΔR/R%) of ~164 at 120 °C with 50 ppm of NO 2 gas. • The selectivity of the sensor is supported by electronic structure calculations. • The sensing mechanism responsible for the dramatically increased sensitivity was also discovered. [ABSTRACT FROM AUTHOR]