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We establish factoriality and non-injectivity in full generality for the mixed q-Araki–Woods von Neumann algebra associated to a separable real Hilbert space H R with dim H R ≥ 2 , a strongly continuous one parameter group of orthogonal transformations on H R , a direct sum decomposition H R = ⊕ i H R (i) , and a real symmetric matrix (qij) with supi,j|qij| < 1. This is achieved by first proving the existence of conjugate variables for a finite number of generators of the algebras (when dim H R < ∞), following the lines of Miyagawa–Speicher and Kumar–Skalski–Wasilewski. The conjugate variables belong to the factors in question and satisfy certain Lipschitz conditions. [ABSTRACT FROM AUTHOR]

For the perovskite halides, current voltage hysteresis is the biggest puzzle to be solved before industrialization in spite of promising features for future photo-voltaic applications. All the possible causes, from the classical (viz., morphology, defects, slow transient capacitance, etc.) to quantum (viz., spin–orbit interaction) ones, are investigated. However, its origin is still under debate, as possibilities showed some ambiguity on the science known until now. In the present work, we have studied the time dependent photo-conduction behavior of CsPbBr 3 in continuous illumination of AM 1.5 G Sun light for 3 h. We observed a negative differential resistance for a forward scanned current–voltage curve in AM 1.5 G Sun light. Our investigations suggest that the photo-current voltage hysteresis is primarily affected by the thermionic-field emission, which slows down the drift velocity of hot charge carriers with field applications. This study will further lead the scientific community to investigate whether this slowdown in drift velocity is related to the Gunn effect or the Rashba effect. [ABSTRACT FROM AUTHOR]

The present study pertains to magnetoelectric coupling and energy storage analysis of (1 − x)BiFe0.95Mn0.05O3-xBaTiO3 (BFMO-BT) with x = 0.1, 0.2, 0.3 lead free solid solutions. BFMO-BT solid solutions possessed a cubic structure as confirmed from powder XRD and the Rietveld refinement. A maximum ferroelectric polarization of 0.82 μC/cm2 was observed in BFMO-0.3BT. BFMO-0.3BT exhibited a maximum energy storage density (WU) of 1.97 J/cm3 and an energy conversion efficiency of 81.7%. Enhanced bulk magnetization was associated with the lattice defects; however, it decreased with increased BT content. For BFMO-0.3BT, temperature dependent susceptibility, dielectric measurement, and differential scanning calorimetry measurement revealed the magnetic transition temperature to be 275 °C, 293 °C, and 223 °C, respectively. The linear magnetoelectric coupling coefficient was measured by quantifying change in maximum polarization with respect to the applied magnetic field and was found to be 28.55 mV cm−1 Oe for BFMO-0.3BT. Conductivity measurements of BFMO-0.3BT revealed a maximum value of activation energy, i.e., 0.21 eV at 1 kHz. [ABSTRACT FROM AUTHOR]

Complex and active fluids find broad applications in flows through porous materials. Nontrivial rheology can couple to porous microstructure leading to surprising flow patterns and associated transport properties in geophysical, biological, and industrial systems. Viscoelastic instabilities are highly sensitive to pore geometry and can give rise to chaotic velocity fluctuations. A number of recent studies have begun to untangle how the pore-scale geometry influences the sample-scale flow topology and the resulting dispersive transport properties of these complex systems. Beyond classical rheological properties, active colloids and swimming cells exhibit a range of unique properties, including reduced effective viscosity, collective motion, and random walks, that present novel challenges to understanding their mechanics and transport in porous media flows. This review article aims to provide a brief overview of essential, fundamental concepts followed by an in-depth summary of recent developments in this rapidly evolving field. The chosen topics are motivated by applications, and new opportunities for discovery are highlighted. [ABSTRACT FROM AUTHOR]

Estimation of module temperature is important for the assessment of performance and reliability of photovoltaic (PV) modules. The objective of the present work is to develop a simple model for estimation of module temperature of water-based PV systems. In this paper, a new approach has been proposed to incorporate the effect of water on PV module temperature. PV modules experience differential heat exchange from their front and rear sides under the influence of water. Therefore, in the proposed approach, separate thermal loss coefficients have been calculated for the front and rear sides of PV modules. The experimentally measured data of a complete year has been utilized to determine the thermal loss coefficients of front and rear sides of PV modules. These coefficients have been used along with PV module technology parameters for predicting module temperature. The ratio of front and rear side thermal loss coefficient of hetro-junction with intrinsic thin layer (HIT), multi-crysalline Silicon (mc-Si), and Cadmium Telluride (CdTe) PV technologies is found to be 0.537, 0.556, and 0.363, respectively. The developed model has been validated using an experimental setup comprising of three different PV module technologies. The mean bias error and root mean square error for the developed model have been found to be less than 0.5 °C and approximately 3 °C, respectively. This shows that the developed model is accurate enough and consistent for temperature estimation of different PV module technologies on water bodies. [ABSTRACT FROM AUTHOR]

Polymeric flow through porous media is relevant in industrial applications, such as enhanced oil recovery, microbial mining, and groundwater remediation. Biological processes, such as drug delivery and the transport of cells and particles in the body, also depend on the viscoelastic flow through the porous matrix. Large elastic stresses induced due to confined geometries can lead to elastic instability for the viscoelastic fluid flow through porous media. We have numerically studied viscoelastic flow through a channel having two closely placed cylinders to investigate pore scale elastic instabilities. We have discovered three distinct flow states in the region between the cylinders. These flow states are closely coupled with the topology of the polymeric stress field. The transition between the flow states can be identified with two critical Weissenberg numbers ( Wi cr 1 and Wi cr 2 ), where the Weissenberg number (Wi) is the ratio of elastic to viscous forces. At Wi < Wi cr 1 , the flow is stable, symmetric, and eddy free. For Wi cr 1 < Wi < Wi cr 2 , eddies form in the region between the cylinders. We have measured the area occupied by the eddies for different flow conditions and fluid rheological parameters. At Wi > Wi cr 2 , the eddy disappears and the flow around the cylinders becomes asymmetric. We have quantified the flow asymmetry around the cylinders for different flow rates and fluid rheology. We have also studied the effect of the cylinders' diameter and separation on the eddies' size ( Wi cr 1 < Wi < Wi cr 2 ) and flow asymmetry (Wi > Wi cr 2 ). We have also investigated the effect of fluid rheology and cylinders' diameter and separation on the value of critical Weissenberg numbers. [ABSTRACT FROM AUTHOR]

The valence and conduction band offsets of Zn1-xCd1-xO/ZnO hetero-junctions deposited by pulsed laser deposition technique were estimated by X-ray photoelectron, valence band, and UV-visible spectroscopy. Type-II band alignment (staggered gap) with ratios of conduction band to valence band offsets (ΔEC/ΔEV) was found to be 0.77 and 0.59 for Zn0.95Cd0.05O/ZnO and Zn0.90Cd0.10O/ZnO hetero-structures, respectively, which can be used in longer wavelength regime optoelectronic devices. The higher value of valence band offset as compared to conduction band offset suggests that the transport at interface is mainly due to electrons. [ABSTRACT FROM AUTHOR]

Here, we present the low temperature magnetic behaviour of epitaxial La0.7Ca0.3Mn0.85Al0.15O3 (LCMAO) thin film through a series of DC magnetic measurements. Overall behaviour inferred from the magnetization measurements indicate that the magnetic phases created due to Al doping induced inhomogeneous distribution of Mn3+ and Mn4+ ions and oxygen vacancies present in the system act like superspins, and the strong interaction among themselves results in the superspin glassy behaviour. Interactions among the superspins are marked by the aging and zero filed memory effects. The glassy magnetic phase in LCMAO is found to follow the hierarchical model of spin glasses. [ABSTRACT FROM AUTHOR]

Lead-free double perovskite materials (viz., Cs2AgInCl6) are being explored as stable and nontoxic alternatives of lead halide perovskites. In order to expand the optical response of Cs2AgInCl6 in the visible region, we report here on the stability, electronic structure, and optical properties of Cs2AgInCl6 by sublattice mixing of various elements. We have employed a hierarchical first-principles-based approach starting from density functional theory (DFT) with appropriate exchange-correlation functionals to beyond DFT methods under the framework of many body perturbation theory (viz., G0W0@HSE06). We have started with 32 primary set of combinations of metals M(I), M(II), M(III), and halogen X at Ag/In and Cl sites, respectively, where the concentration of each set is varied to build a database of nearly 140 combinations. The most suitable mixed sublattices are identified to engineer the bandgap of Cs2AgInCl6 to have its application in optoelectronic devices under visible light. [ABSTRACT FROM AUTHOR]

The present work demonstrates the effect of the grain size on electrocaloric and pyroelectric properties in BaTiO3-based ceramics prepared by a chemical coating method and then sintered in a reducing atmosphere at different temperatures. In a grain size of 136 ± 50 nm to 529 ± 245 nm, the electrocaloric temperature change increases from 0.30 K to 0.63 K under the electric field of 4 MV/m at the ferroelectric–paraelectric phase transition. The corresponding entropy change, heat extraction capacity, coefficient of performance, and electrocaloric strength exhibit a twofold increase (i.e., 0.31 J/kg K–0.75 J/kg K, 148 J/kg–303 J/kg, 7–14, and 0.0075 K cm/kV–0.016 K cm/kV, respectively). The effects of the grain size on the pyroelectric properties are established from the pyroelectric coefficient and the associated pyroelectric figures of merit (FOMs). The pyroelectric coefficient and pyroelectric FOMs exhibit about a fivefold increase with the increasing grain size. The pyroelectric energy harvesting is calculated for the Olsen cycle. The energy harvesting capabilities enhance from ∼96 kJ/m3 to ∼135 kJ/m3 when the cycle is operated at temperatures between 303 K and 423 K and an electric field between 1 MV/m and 4 MV/m. The results show that the increase in the grain size significantly improves the electrocaloric and pyroelectric properties. Furthermore, it is established that the pyroelectric properties are more sensitive to the grain size as compared to the electrocaloric effect when ceramics are prepared by the chemical coating-cum-sintering route. In summary, the present study suggests that microstructure control in BaTiO3 fabrication with the enhanced grain size can be an effective approach to enhance the pyroelectric and electrocaloric properties. [ABSTRACT FROM AUTHOR]

The coalescence dynamics of an ethanol droplet freely falling on a sessile ethanol droplet is investigated experimentally using a high-speed imaging system. The regime maps showing the partial coalescence and spreading behaviors in the plane of the Weber number (We) and the volume of the sessile droplet (Vp) normalized with the volume of the impacting droplet (Vi) have been presented. The partial coalescence phenomenon is observed when the ratio of the volume of the sessile droplet to that of the impacting droplet (Vp/Vi) is greater than two. For Vp/Vi = 2, the size of the daughter droplet is found to be about 0.1 times as that of the impacting droplet, which increases with the increase in the We and normalized volume of the sessile droplet. In the present study, the negative curvature of the droplet coupled with the presence of the substrate leads to a different coalescence dynamics. [ABSTRACT FROM AUTHOR]

Ag:ZrO2 nanocomposite films have been synthesized by a sol-gel dip coating process at room temperature, followed by irradiation using swift heavy ions. The effect of electronic energy loss and fluences on the evolution and consequently on the tailoring of plasmonic properties of films has been studied. The optical study exhibits that color of films converts from transparent in pristine form into shiny yellow when films are irradiated by 100 MeV Ag ions at a fluence of 3×1012 ions/cm2. However, irradiation by 120 MeV O ions up to the fluence of 1 × 1014 ions/cm2 does not induce any coloration in films. The coloration is attributed to the evolution of plasmonic feature resulting in a surface plasmon resonance (SPR) induced absorption peak in the visible region. Increase in fluence from 3 × 1012 to 6 × 1013 ions/cm2 of 100 MeV Ag ions induces a redshift in SPR induced peak position from 434 to 487 nm. Microstructural studies confirms the conversion of Ag2O3 (in pristine films) into cubic phase of metallic Ag and the increase of average size of particles with the increasing fluence up to 6 × 1013 ions/cm2. Further increase in fluence leads to the dissolution of Ag atoms in the ZrO2 matrix. [ABSTRACT FROM AUTHOR]

Two parallel semiconductor plates, separated by a short distance, support surface plasmon eigenmode with amplitude maxima at the inner surfaces of the plates and minimum at the center. A relativistic sheet electron beam propagating through the space between the planes resonantly excites the surface plasma wave (SPW). The frequency of the driven SPW decreases with the energy of the beam while the growth rate increases. At the beam current ≈168 A the growth rate of 5.93×108 rad/s is achieved at the frequency ≈0.51 THz of SPW for the 5 mm y⁁ width and spacing between the two plates of ≈2.83 mm. The growth rate scales as 1/3 root of the electron beam current. [ABSTRACT FROM AUTHOR]

An analytical formalism of whistler pumped free electron laser (FEL) with tapered magnetic field is developed. The tapering raises the efficiency of the device to 7% for typical parameters. The frequency and power of the FEL can be controlled by tuning the plasma density and/or magnetic field also by increasing the energy of electron beam. The angle of injection of electron beam is very crucial for higher efficiency of FEL. Presence of plasma ensures the space charge and current neutralization and larger power handling capacity of the device. [ABSTRACT FROM AUTHOR]

Distribution of Zn 2 + , Al 3 + , and Fe 3 + ions on tetrahedral and octahedral sites in Fe 3 + -doped ZnAl 2 O 4 nanocrystals is studied through detailed x-ray diffraction (XRD) analysis. Significant changes in the intensity ratio of (220), (311), (400), and (422) diffraction peaks upon Fe addition were perceived, whose correlation with lattice inversion, Fe 3 + ions distribution, and ionic vacancies is probed through simulations and Rietveld refinement. Fe 3 + ions were found to be occupying tetrahedral sites in increasing proportion with the doping concentration, leading to decreased spinel inversion. However, different orders of defects, viz., cation and anion vacancies were also found to be playing their part in the statistical distribution of cations on octahedral/tetrahedral interstices. Fe L 2 , 3 -edge x-ray absorption near edge structure spectroscopy indicated Fe 3 + ions being present on tetrahedral as well octahedral interstices and distortion in cation polyhedra, while O K-edge inferred formation of different orders of ionic vacancies upon Fe addition, thereby corroborating the results from XRD. The photoluminescence study illustrated the quenched emission intensity upon Fe doping, with almost no change in emission color, and signatures of tetrahedral/octahedral Fe 3 + occupancy in the lattice. Thus, this study highlights the variation in degrees of freedom associated with atomic arrangements in spinel ZnAl 2 O 4 lattice upon Fe 3 + addition. [ABSTRACT FROM AUTHOR]

Simultaneously achieving higher carriers concentration and mobility is a technical challenge against up-scaling the transparent-conductive performances of transparent-conductive oxides. Utilizing one order higher dense (~1 × 1011 cm-3) plasmas (in comparison to the conventional direct current plasmas), highly c-axis oriented Al-doped ZnO films have been prepared with precise control over relative composition and chemical states of constituting elements. Tailoring of intrinsic (O vacancies) and extrinsic (ionic Al and zero-valent Al) dopants provide simultaneous enhancement in mobility and concentration of charge carriers. Room-temperature resistivity as low as 4.89 × 10-4 Ω cm along the carrier concentration 5.6 × 1020 cm-3 is obtained in 200 nm thick transparent films. Here, the control of atomic Al reduces the charge trapping at grain boundaries and subdues the effects of grain boundary scattering. A mechanism based on the correlation between electron-hole interaction and carrier mobility is proposed for degenerately doped wide band-gap semiconductors. [ABSTRACT FROM AUTHOR]

Ferromagnetic and large magnetoresistance (MR) nanocomposites of La0.67Sr0.33MnO3-BaTiO3 (LSMO-BTO) are synthesized via sol-gel route. The X-ray diffraction confirms the existence of two chemically separated phases in the composites. The maximum MR (35%) was achieved in LSMO-5% BTO (LB5). The coupling between the coexisting phases is observed from the dielectric anomaly at the ferromagnetic transition (Tc=353 K) for LB5 composition. We observed maximum magnetodielectric effect at Tc of 1.18% in magnitude for LB5 and the effect of magnetic field on other composites was significant. These results are related to the large spin polarization within grains as well as at the grain boundaries and the evidence of variation in dielectric parameters with magnetic field reveal the magnetoelectric coupling in LSMO-BTO nanocomposites. [ABSTRACT FROM AUTHOR]

Ferromagnetic and large magnetoresistance (MR) nanocomposites of La0.67Sr0.33MnO3-BaTiO3 (LSMO-BTO) are synthesized via sol-gel route. The X-ray diffraction confirms the existence of two chemically separated phases in the composites. The maximum MR (35%) was achieved in LSMO-5% BTO (LB5). The coupling between the coexisting phases is observed from the dielectric anomaly at the ferromagnetic transition (Tc = 353 K) for LB5 composition. We observed maximum magnetodielectric effect at Tc of 1.18% in magnitude for LB5 and the effect of magnetic field on other composites was significant. These results are related to the large spin polarization within grains as well as at the grain boundaries and the evidence of variation in dielectric parameters with magnetic field reveal the magnetoelectric coupling in LSMO-BTO nanocomposites. [ABSTRACT FROM AUTHOR]

We propose a simple and straightforward method to generate spatially variant lattice structures by optical interference lithography method. Using this method, it is possible to independently vary the orientation and period of the two-dimensional lattice. The method consists of two steps which are: numerical synthesis of corresponding phase mask by employing a two-dimensional integrated gradient calculations and experimental implementation of synthesized phase mask by making use of a phase only spatial light modulator in an optical 4f Fourier filtering setup. As a working example, we provide the experimental fabrication of a spatially variant square lattice structure which has the possibility to guide a Gaussian beam through a 90° bend by photonic crystal self-collimation phenomena. The method is digitally reconfigurable, is completely scalable, and could be extended to other kind of lattices as well. [ABSTRACT FROM AUTHOR]

Electronic structure of pulsed laser deposited hexagonal-YMnO3 film on Al2O3 (0001) substrate has been investigated by photoemission spectroscopy using variable energy photon sources. Resonance photoemission results reveal the charge transfer nature of h-YMnO3 and variation in strength of hybridization between oxygen 2p and Mn 3d across the valence band region. The valence states sensitive to lattice distortion (inversion asymmetry) demonstrate the evolution of spin orbit interaction (SO). This SO along with its anisotropic behavior is well identified by the constant initial state plots. [ABSTRACT FROM AUTHOR]

Publisher's Note: "Sublattice mixing in Cs2AgInCl6 for enhanced optical properties from first-principles" [Appl. Phys Lett. HT ht (3) All online versions of the article were corrected on 19 January 2021. This article was originally published online on 15 January 2021 with an error in Eq. (3). [Extracted from the article]

The morphology of the spin-coated photoactive layer is one of the major factors affecting the performance of perovskite solar cells. In this work, we have employed a mixed-solvent strategy to obtain a high quality MAPbI3 (MA=CH3NH3) perovskite film, without pinholes and reduced grain boundaries. Perovskite films formed with single and mixed-solvents are systematically characterized for their optical, structural, and morphological properties using UV-vis absorption, photoluminescence (PL), X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) tools. The power conversion efficiency (PCE) of the devices fabricated using the mixed-solvent showed better performance than the devices made using the single solvent. The best-optimized mixed-solvent perovskite film exhibited a PCE of 15.2% with uniform film coverage on the substrate, better charge generation, and a high hole mobility of 1.16X10-4cm2/ Vs. The disparities in photovoltaic properties have been analyzed with the intensity dependent current density-voltage (J-V), transient photovoltage (TPV), and relationship between photocurrent (Jph) and effective voltage (Veff). [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Zero-field cooled exchange bias in hexagonal YMnO3 nanoparticles" that was published in the 2013 issue.