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The present work explains the structural and magnetic properties of Ho doped barium hexaferrite. The BaFe12-xHoxO19 (x = 0.0, 0.25, and 0.50) were synthesized by the sol-gel method and annealed at 850 °C. The average crystallite size decreases with the increase in Ho concentration in barium hexaferrite. The “Law of Approach to Saturation model” is employed to determine the magnetocrystalline anisotropy constant as well as saturation magnetization. The saturation magnetization decreases and coercivity increases with the increase in Ho concentration in barium hexaferrite. The decrease of saturation magnetization with the Ho concentration could be due to the reduction of average crystallite size as well as the presence of secondary phase in the Ho doped samples. The magnetic parameters of barium hexaferrite depend on Fe-O-Fe superexchange interaction and average crystallite size which is considered to explain the magnetic properties of the Ho doped barium hexaferrite. Also, the presence of an extra phase has been considered to explain the magnetic properties of Ho doped barium hexaferrite.

Of late, d0 ferromagnetic oxide materials have been studied as potential material for spintronics application. We investigate the crystal structure, magnetic, optical, and dielectric properties of Ag-doped TiO2 compounds. XRD study reveals polycrystalline rutile form of TiO2 with tetragonal-type structure. SEM micrographs show spherical particles of size 2–3 µm. All the compounds exhibit ferromagnetism with Curie temperature beyond 400 K and with a typical coercivity value in the range 130–550 Oe. The bifurcation of ZFC and FC M–T curves points out magnetic irreversibility. All Ag-doped TiO2 compounds exhibited p-type conductivity as per the Hall effect study. Optical absorbance data indicate the widening of the band gap up to 6% of Ag doping followed by a decrease for higher doping and these materials exhibit transmittance in the range of 20–30%. The compounds exhibit zero dielectric loss and appreciable dielectric constant and their AC conductivity increases with Ag doping.

We have fabricated VO2 nano-columns (NCs) on the aluminized quartz glass substrates using glancing angle deposition (GLAD) technique inside the electron beam (e-beam) evaporator chamber. An e-beam deposited TiO2 thin cap-layer has been introduced on the top of the VO2 NCs to protect VO2 phase which is usually unstable and turns to stable higher oxidation state, i.e., V2O5. The X-ray diffraction (XRD) analysis of TiO2 thin film (TF) coated VO2 NCs shows the presence of VO2 phases along with the other oxidation states. The Fourier-Transform-Infrared-Spectroscopy (FTIR) confirms the presence of Ti–O–V, V–O vibrations bands in VO2 NCs/TiO2 TF samples. The VO2 NCs/TiO2 TF sample possesses a sharp drop (~103 order) in resistance at the transition temperature (Tc) ~66 °C. This sample also shows a stable semiconducting to metallic phase (vice versa as well) transition temperature (PTT) hysteresis even after one month which ensures the stable performance in terms of phase transition characteristic. Small-radius polaron model (SRPM) is used to calculate the sheet resistance of the VO2 NCs, where we consider the effect of thermal lattice vibrations on the overlap integral of the crystal atoms. The temperature dependency of constants A and e have been observed uniquely. The Fermi-Dirac (F-D), Migdal distribution (MD) model have been taken into account for the first time to calculate the conduction band carrier density of VO2 NCs and ratio of the resistance in the semiconducting (RS), metallic phase (RM) is also calculated. The calculated electron concentration ( n c ) is 3.1 × 1019 cm-3 at the point of PTT (66 °C).

The evolution of microstructure (grain size) with the sintering temperature and its effect on the electrical properties has been investigated for ((Bi0.5Na0.5)0.94Ba0.06)0.70Sr0.30TiO3 [BNBSTO] electroceramic. The X-ray diffraction patterns and the Rietveld refinements reveal the formation of the single phase with perovskite structure. The relative dielectric constant increases with the sintering temperature up to 1175 °C. Temperature-dependent relative permittivity shows the dispersive nature with the diffuse electrical phase transitions. The diffusivity of the electrical properties of the electroceramics has been estimated using the Curie–Weiss law. It is observed that the electrical diffuseness decreases with the increase of the grain size. The Nyquist plots reveal the role of grains and grain boundaries on the electrical conductivity of the electroceramic. Also, the grain size affects the ferroelectric properties which directly influences the energy storage density.

Organotrialkoxysilanes, particularly amino-glycidoxy and epoxy-functionalized alkoxysilanes, allow for the controlled synthesis of noble metal nanoparticles and bimetallic nanoparticles; these materials enable a concentration-dependent enhancement in resonance Rayleigh scattering, which may be useful for the selective detection of hydrazine. 3-aminopropyltrimethoxysilane (3-APTMS)-treated gold cations were converted into gold nanoparticles within a few seconds (

The present work includes the fabrication of Mg0.4Ti0.6O2 thin film (TF) based Metal-oxide–semiconductor (MOS) capacitor on (1 0 0) n-type GaAs substrates by electron beam evaporation technique. The thickness of the thin film alloy is found to be about 300 nm measured from Field emission gun-scanning electron microscope (FEG-SEM) data. The pore volume, surface roughness and grain size of the thin film samples are calculated from non-contact atomic force microscopy (NC-AFM) images. Experimental as well as analytical studies have been carried out to determine the bandgap and defect level transition of the material. The band-to-band transition of the Mg0.4Ti0.6O2 sample is calculated to be at ~ 5.2 eV. The as prepared sample shows tetragonal crystal structure. Presence of anatase phase of TiO2 in the TF material is confirmed through XRD (X-ray diffraction) investigation. Current (I) – Voltage (V) characteristics of the Mg0.4Ti0.6O2 Schottky devices reveal that the leakage current at −1 V is 8.1 × 10-4 A.

Benzoic acid derivatives are important molecular systems in the pharmaceutical industry. Salicylic acid is distinct among the derivatives of benzoic acid due to the presence of an intramolecular hydrogen bond. With a view to study the evolution of inter and intramolecular hydrogen bonding at shorter length scales, in situ high pressure Raman spectroscopic measurements, angle dispersive X-ray diffraction experiments, and density functional theory (DFT) based first principle calculations have been carried out on crystalline salicylic acid. Subtle structural modifications are noted across ∼1 GPa leading to structural phase transition to a new crystalline phase above 7 GPa which is reversible. Substantial softening of the OH stretching Raman mode associated with intramolecular hydrogen bond is observed prior to the transition pressure. Possible molecular configurations associated with tautomerization are discussed with the aid of DFT calculations.

Aluminum nanoparticles (AlNPs) were embedded into a sol-gel synthesized In₂O₃ thin film by using a combination of thermal evaporation and glancing Angle Deposition technique. Presence of different sizes of aluminum nanoparticles was confirmed from field emission gun scanning electron microscopy. The high-resolution X-ray diffraction confirms the formation of Al₂O₃ NPs by surface oxidation of aluminum nanoparticles. Embedded Metal-Oxide-Semiconductor like device Al/In₂O₃/AlNPs/In₂O₃/p-Si was fabricated, and its memristor behavior was analyzed. The Al/In₂O₃/AlNPs/In₂O₃/p-Si device possessed high current conduction and analog resistive switching as compared to Al/In₂O₃/p-Si device. Significant and consistent memory window up to 150 current (I)-voltage (V) loop was obtained for Al/In₂O₃/AlNPs/In₂O₃/p-Si device between ±6 V applied bias. The Al/In₂O₃/AlNPs/In₂O₃/p-Si device measured high free carrier concentration, i.e., (Nd)~1.93 × 1020 cm-3 calculated from capacitance (C)-Voltage (V) measurement. The memory was retained in accumulation and depletion regions as obtained from the C-V looping curves.

A series of hybrid proton exchange membranes were synthesized via in situ polymerization of poly (2-acrylamido-2-methyl-1-propanesulfonic acid) PMPS with sulfonated poly (1,4-phenylene ether-ether-sulfone) (SPEES). The insertion of poly (2-acrylamido-2-methyl-1-propanesulfonic acid) PMPS, between the rigid skeleton of SPEES plays a reinforcing role to enhance the ionic conductivity. The synthesized polymer was chemically characterized by fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance 1H NMR spectroscopy to demonstrate the successful grafting of PMPS with the pendent polymer chain of SPEES. A variety of physicochemical properties were also investigated such as ion exchange capacity (IEC), proton conductivity, water uptake and swelling ratio to characterize the suitability of the formed polymer for various electrochemical applications. SP-PMPS-03, having the highest concentration of all PMPS, shows excellent proton conductivity of 0.089 S cm&minus, 1 at 80 &deg, C which is much higher than SPEES which is ~0.049 S cm&minus, 1. Optimum water uptake and swelling ratio with high conductivity is mainly attributed to a less ordered arrangement polymer chain with high density of the functional group to facilitate ionic transport. The residual weight was 93.35, 92.44 and 89.56%, for SP-PMPS-01, 02 and 03, respectively, in tests with Fenton&rsquo, s reagent after 24 h. In support of all above properties a good chemical and thermal stability was also achieved by SP-PMPS-03, owing to the durability for electrochemical application.

Electron beam evaporation technique is employed to synthesise TiO2, Mg0.1Ti0.9O2 and Mg0.2Ti0.8O2 thin films (TFs) grown on (100) n-type GaAs substrates. Field emission gun-scanning electron microscope (FEG-SEM) results show that the TFs have a thickness of ~225 nm. The non- contact atomic force microscopy (NC-AFM) images shows the pore volume of the TiO2, Mg0.1Ti0.9O2 and Mg0.2Ti0.8O2 TFs enhanced gradually. UV-Vis absorption measurements are performed on the samples to determine the main bandgap and defect level transition of the material. A unique modified Urbach theoretical model has been introduced to simulate the experimental absorption spectrum. The main bandgap energy of the TiO2, Mg0.1Ti0.9O2 and Mg0.2Ti0.8O2 samples are calculated to be ~3.45 eV, 3.85 eV and 4.30 eV respectively. A gradual enhancement in main bandgap transition probability and decrease in defect level transition of the material has been observed with enhanced incorporation of Mg into the TiO2 host material. X-ray diffraction (XRD) is performed, which shows a continuous change in lattice constant of TiO2 with Mg. Current (I)-voltage (V) characteristics of the TiO2, Mg0.1Ti0.9O2 and Mg0.2Ti0.8O2 Schottky devices revealed that the leakage current at −1 V was 1.28 × 10−6 A, 1.46 × 10−9 A and 2.44 × 10−10 A respectively. Capacitance (C)–voltage (V) measurements are performed on the devices at different frequencies. A theoretical simulation has been adopted by amending the delta depletion model at 1 MHz. The dielectric constant and the flat band voltage of the TiO2, Mg0.1Ti0.9O2 and Mg0.2Ti0.8O2 devices are found to be 100, 120 and 160 and 16.1 V, 14.7 V and 9.7 V respectively. Hill-Coleman’s method shows a gradual enhancement of the density of interface states (Dit) with Mg concentration. The calculated Dit value of the TiO2, Mg0.1Ti0.9O2 and Mg0.2Ti0.8O2 TF devices are ~6.16 × 1010 eV−1 cm−2, 6.44 × 1010 eV−1 cm−2 and 1.11 × 1011 eV−1 cm−2 respectively. The observed C-V hysteresis confirms an enhancement in the charge retention into the film with increasing Mg concentration, which in turn improves the memory window (MW) from ~0.36 V (at±7 V) to ~0.67 V (at±7 V) and ~0.87 V (at±10 V) to ~1.0 V (at±10 V) with sweeping voltage.

We have reported a new method of synthesis of InN nanowires (NWs) on p-Si (100) substrate by the vapour transport cum glancing angle deposition (GLAD) technique. The field emission gun transmission electron microscopy (FEG-TEM) reveals that the InN NWs are crystalline in nature. Photoluminescence (PL) analysis shows that the optical bandgap of the NW is ~1.07 eV at 300 K. Metal-Semiconductor-Metal (M-S-M) photodetecor has been fabricated using InN NWs. The device produced trivial dark current ~7.31 μA cm -2 at 3 V applied voltage. The broad band near-infrared (NIR) photo-response from 900-1400 nm was recorded for the device.

Because of a unique sandwiched structure of proton and anion exchange membranes, the bipolar membrane (BPM) enables self-humidification at their junction in fuel cell operation. In this work, a nov...

The lanthanum (La3+) doped M-type barium hexaferrite (Ba1−xLaxFe12O19) with x = 0.0, 0.05, 0.10, 0.15, and 0.20 have been prepared by the sol-gel technique. The Rietveld refinement of X-ray diffraction (XRD) patterns reveals the crystallization of all the samples to hexagonal crystal symmetry with P63/mmc space group. Investigation of Raman spectra strongly supports the XRD pattern analysis. The average grain (particle) size is found to be above 300 nm. Both the saturation magnetization and magnetocrystalline anisotropy have been estimated by employing the “Law of Approach (LA) to Saturation magnetization”. Both the above parameters are found to be maximum for 10% La doped BaFe12O19. It could be due to the lattice strain mediated magnetism in barium hexaferrite. However, these magnetic parameters decrease with the increase in La doping beyond 10% (>x = 0.10) in barium hexaferrite. The dielectric permittivity gradually increases with the La concentration in the BHF. A correlation between dielectric constant with the lattice strain has been reported in La3+ doped barium hexaferrite.

High pressure angle-dispersive X-ray diffraction investigations have been carried out on α-cristobalite form of Al0.5Ga0.5PO4. Our investigations show that the structural stability of this phase un...

Nanochannels were created in poly(vinylidene fluoride) and its nanohybrid films by bombarding with high-energy swift heavy ions. The nanochannel dimensions of the membranes varied from 80 to 100 nm using 5 × 107 ion fluence of SHIs. The walls of the nanochannels were grafted with the monomer 3-hexylthiophene using the free radicals generated by the swift heavy ions, which was followed by their sulphonation for better ion conduction. Organically modified nanoclay enhanced the electroactive β-phase in the polymer and its extent increased after irradiation, grafting and sulphonation, resulting in a better material for different electroactive applications. The semiconducting current–voltage characteristics of the functionalized nanochannels were studied through a parameter analyzer of the bulk film against the insulating behavior of the neat polymer. The current–voltage characteristic of the membrane exhibited strong dependency on functionalization and showed superior conduction in the functionalized nanohybrid membrane. The proton conductivity of the functionalized nanohybrid was 4.59 × 10−2 S cm−1 at 30 °C, while methanol permeability was drastically reduced as compared to that of standard Nafion 117; this indicated the higher values of the selectivity parameter, which is a key feature of the better performance of the fuel cell membrane: 1.02 × 105 S cm−3 s as opposed to the value of 0.73 × 105 S cm−3 s for Nafion 117. The membrane electrode assembly studies of the functionalized nanohybrid showed 0.76 V open circuit voltage, leading to power density of 92 mW cm−2 and current density of 252 mA cm−2, which were significantly higher than those of the functionalized pure polymer and standard Nafion 117 membrane, indicating its good potential for applications in fuel cells.

Organotrialkoxysilanes like 3-aminopropyltrimethoxysilane (3-APTMS)-treated noble metal cations were rapidly converted into their respective nanoparticles in the presence of 3-glycidoxypropylytrimethoxysilane (3-GPTMS). The micellar activity of 3-APTMS also allowed us to replace 3-GPTMS with other suitable organic reagents (e.g., formaldehyde); this approach has significant advantages for preparing bimetallic and trimetallic analogs of noble metal nanoparticles that display efficient activity in many practical applications. The formation of monometallic gold, silver, and palladium nanoparticles, bimetallic Ag-Pd, and Au-Pd nanoparticles at various ratios of noble metal cations, and trimetallic Ag-Au-Pd nanoparticles were studied; their biocatalytic activity in non-enzymatic sensing of glucose based on monitoring synchronous fluorescence spectroscopy (SFS) was assessed. Of these nanoparticles, Au-Pd made with an 80:20 Au:Pd ratio displayed excellent catalytic activity for glucose sensing. These nanoparticles could also be homogenized with Nafion to enhance the resonance Rayleigh scattering (RRS) signal. In this study, the structural characterization of noble metal nanoparticles as well as bi- and tri-metallic nanoparticles in addition to their use in non-enzymatic sensing of glucose are reported.

The copper ferrite fiber has been synthesized using the electrospinning technique by optimizing the electric voltage and viscosity of the polymer solution. Physical properties of copper ferrite fiber have been tuned with annealing at different temperatures (550, 750, and 950 °C for 2 h). The crystal structure has been confirmed by X-ray-diffraction pattern analysis and studied by using Rietveld refinement technique. The morphology of fibers was explored with the help of field emission scanning electron microscopy. The fibers annealed at 550 °C crystallize to cubic structure, and the tetragonal phase has been observed for 750 °C, and 950 °C annealed fibers. Sample annealed at 750 °C shows the highest magnetocrystalline anisotropy constant at 300 K (3 × 105 erg/cc). The SAR (Specific absorption rate) and ILP (intrinsic loss power parameter) of the 750 °C annealed fibers are 265 ± 5 W/g and 3.412 nHm2/Kg, respectively. The SAR value calculated by using non-adiabatic approach is 335 W/g.

Nickel-palladium bimetallic nanocrystallite supported mesoporous silica/silica nanoparticles (MSPs/MSNPs) made at a controlled ratio of Pd/Ni via organotrialkoxysilane mediated reduction of palladium cations are reported. The organotrialkoxysilane serve as a template for the stabilization and formation of bimetallic Pd-Ni nanocrystallite within MSPs/MSNPs that are characterized by TEM, EDX, HR-SEM, HR-MS, XRD, BET and Elemental mapping analysis, kinetic analysis for degradation of both cationic and anionic dyes, i.e., rhodamine B and congo red, respectively. The nanocrystallite inserted MSNPs of particle diameter 200 nm justify faster degradation with rate constant to the order of 6.9 x10

Barium hexaferrite (BHF) is a promising material for technological applications. Hence, the large production of BHF for industrial application needs attention. Therefore, the effect of annealing temperature on the crystal structure, morphology, and magnetic properties of barium hexaferrite has been explored in this article. The BaFe12O19 (BHF) was prepared by the sol–gel method and annealed at different temperatures (800 °C, 900 °C, 1000 °C, and 1100 °C). The crystal structure of BHF is investigated by the Rietveld refinement of XRD patterns using Fullprof suit software. Bond lengths and bond angles have been calculated using the Rietveld refined crystal structure parameters. The FESEM micrograph reveals the cylindrical shape of BHF particles for the samples annealed above 900 °C. Large average grain size has been observed for 1100 °C annealed BHF sample. The average crystallite size (obtained from XRD analysis) and particle size (obtained from FESEM) increase with an increase in annealing temperature of BHF. It is observed that the magnetic properties of BHF depend on bond angles and bond lengths between Fe and O atoms at different crystallographic sites. The saturation magnetization and coercivity are found to increase with the increase in average crystallite or particle size, but the variation is very small.

Vitamin D3 acts as a crucial biomarker for various diseases. Current methods for vitamin D3 detection are time-consuming, expensive, and require trained personnel. We report a simple and cheap photodetector (PD)-based vitamin D3 detection technique for the first time using Ag nanoparticles-covered Er-doped TiO2 nanowires. The operational stability of the device was tested under the dark as well as the UV light illumination. Vitamin D3 solution produced absorption bands at 222 and 280 nm, respectively. The PD current density varied from 1.29 × 10 − 4 A / cm2 to 1.74 × 10 − 4 at −4 V for pure ethanol solution and 20 pg / ml D3 solution, respectively (under 220 nm illumination). The average absolute current values were reduced from 3.25 nA (220 nm) and 2.9 nA (340 nm) for 5 pg / ml to 2.95 nA (220 nm) and 2.54 nA (340 nm) for 30 pg / ml D3 solution, respectively. The current gradually increased up to 3.34 nA (220 nm) and 2.7 nA (340 nm) as the concentration was increased up to 80 pg / ml. The PD current/vitamin D3 concentration decreases exponentially from 0.58 to 0.03 nA / g / ml) for 5 and 80 pg / ml, respectively, under 220 nm excitation, from which an unknown concentration of vitamin D3 can be obtained.

We have systematically investigated the elastic properties (&rho, VP, VS, K, and &sigma, ) of eight SiO2&ndash, TiO2 glasses, varying in composition from 1.3 to 14.7 wt% TiO2, as a function of pressure up to 0.5 GPa by the pulse superposition (PSP) ultrasonic technique, and two compositions (1.3 and 9.4 wt% TiO2) up to ~5.7 GPa by Brillouin scattering in a diamond anvil cell. The parameters were also measured after annealing to 1020 &deg, C. Composition&ndash, elasticity relationships, except for K and &sigma, are more or less linear, the annealing simply makes the relationships more uniform (less scatter). There is excellent agreement between the ultrasonic and Brillouin measurements at ambient and high pressure. The pressure-induced anomalous elastic behavior (negative dVP/dP and dK/dP) becomes more negative (more compressible) with the increasing TiO2 content. Correspondingly, the acoustic Gr&uuml, neisen parameters become more negative with increases in the TiO2 content, reaching a minimum near ~8&ndash, 10 wt% TiO2. The comparison of the low- and high-pressure ultrasonic and Brillouin VP and VS in two glasses (1.3 and 9.4 wt% TiO2) shows excellent agreement, defining the reversible elastic behavior at low pressures and irreversible behavior at higher pressures (&ge, 5.7 GPa) well. This result is consistent with our previous high-pressure Raman study showing an irreversible structural change in a similar pressure range.

In the literature, it is found that the experimental value of saturation magnetization for Co2TiAl1-xSix (0≤x≤1) quaternary Heusler alloy is low compared to that of theoretical prediction by the Slater-Pauling rule. Hence, Co2TiAl0.75Si0.25 alloy has been prepared to enhance the saturation magnetization. The sample is characterized by the X- ray diffraction technique and energy dispersive X-ray analysis. Magnetic hysteresis loops are recorded at different temperatures. Temperature dependence of magnetic saturation has been demonstrated by employing the Law of Approach (LA) to saturation and Bloch’s law at low temperature. Saturation magnetization at 0 K (extrapolated) has been found to be 1.09 µB/f.u.. However, anti-site disorder between Ti-Al and spin wave excitation at low temperature cause the reduction of the saturation magnetization at 0 K from the predicted value by the Slater- Pauling rule.

Properties of liquid Fe alloys under high-pressure conditions are crucial for understanding the composition, thermal state, and dynamics of Earth’s core. Experiments on such liquids, however, are often performed under pressures far below those of the outer core, necessitating long extrapolations of experimental results to core conditions. Such estimates can be complicated by light elements possibly forming pressure-dependent molecular clusters that can significantly affect the physical properties of liquids as core conditions are approached. First-principles molecular dynamics simulations were employed to compute the properties of an Fe-Ni-C liquid with a composition of Fe3.7Ni0.37C at 1673 K and pressures from 0 to 67 GPa to benchmark computational methods on pressure effects on the structure and properties of the liquid relative to low pressure experimental results. The short-range structure is manifested by the coordination number (CN) of Fe/Ni-Fe/Ni being around 12, indicative of a nearly close-packed structure in the pressure range, and the CN of C-Fe/Ni gradual increasing from 6.5 to 8.5, indicative of an approximately octahedral to cubic transition as pressure increases. The Fe/Ni-Fe/Ni bond distance, however, is found to be 10 times more compressible than the C-Fe/Ni distance. The intermediate-range structure of Fe/Ni-Fe/Ni and C-Fe/Ni subsystems, described by a partial configurationally-decomposed distribution function, undergoes substantial changes, characterized by a significant increase of the number of polyhedra that share 3 atoms with each other. Such dense configurations are related to an increased bulk modulus, decreased diffusion coefficient, decreased activation volume for diffusion, and increased shear viscosity. Reproducing the experimental observations at low pressures provides important support for modeling the liquid under the conditions relevant to the outer core.

The nanocomposite of ferrites [(60%) BaFe12O19 + (40%) CoFe1.75 Zn0.25O4] has been prepared by the high energy ball milling method. The individual sample BHF (BaFe12O19) and CZF (CoFe1.75 Zn0.25 O4) are synthesized by the modified sol-gel method. The X-ray diffraction technique was employed to study the crystal structure of the sample. The maximum crystallite size of BHF and CZF are found to be 40±2 nm and 36±2 nm respectively in the composite which was annealed at 1000°C. The magnetic hysteresis (M-H) loop of nanocomposite has been recorded by the VSM (vibrational sample magnetometer) technique. The magnetic interaction between soft and hard magnetic phases is studied by plotting the graph between loop width (ΔH) verses magnetization (M). The loop width versus magnetization changes with the annealing temperature due to increase in the particle size. It is observed that there is an interaction between soft and hard magnetic phases. The M-H loops were recorded at different temperatures of sample prepared by the ball milling. Magnetic interaction between soft and hard magnetic phases at low temperature (60K) is different compare to that of room temperature. The maximum magnetic saturation (Ms) and coercivity (Hc) are found to be 77 emu/g and 3.8 kOe at 60K respectively.

The nanocomposites of hard ferromagnetic BaFe12O19 and soft ferrimagnetic CuFe2O4 have been synthesized by the citrate sol-gel method which is calcined at different temperatures (800°C and 1000°C). The crystal structure, microstructural morphology, and magnetic properties were studied by employing the X-Ray Diffraction(XRD), Field- Emission Scanning Electron Microscopy(FE-SEM) and Vibrating Sample Magnetometer(VSM) techniques respectively. The exchange coupling of hard-soft magnetic nanocomposite materials have been explained by the “Henkel plot”. The nature of exchange interaction and magnetic dipole interaction of nanocomposites have been studied from δm vs H plots. This article gives the easy and inexpensive method for the preparation of hard-soft nanocomposites of magnetic materials and enhances its magnetic properties.

Indium Nitride (InN) quantum dots (QDs) were synthesized on Si substrate by oblique angle deposition method. The deposited InN QDs were of the order of 5-50 nm in diameter with density similar to 7 x 10(9)/cm(2) . The synthesized InN QDs were nearly single crystalline, confirmed from the diffraction peak in the < 110 > direction. Photoluminescence (PL) measurement showed peak emission at similar to 1138 nm (1.08 eV) at 19 K. The PL emission energy exhibited blue shift and the intensity reduced with an increase in temperature. The high optical band gap emission of the InN QDs is possibly due to energy level quantization resulted from size reduction. The free carrier concentration was found to be similar to 2 x 10(18) cm(-3). The device selectively detected the 1080 nm (1.13 eV) wavelength with maximum responsivity near the optical band edge at 10 K and room temperature (300 K) respectively. The external quantum efficiency of similar to 4.1% was calculated for the detector at 10 K. The device showed excellent temporal response with rise and fall times of 3.181 s and 3.408 s respectively at 10 K. (C) 2018 Elsevier B.V. All rights reserved.

A sulfonated poly(ether ether ketone) (SPEEK) and phosphorylated graphene oxide (PGO) composite of a cation-exchange membrane with low frictional coefficient and high limiting current density has been reported for water desalination by rapid electrodialysis. The incorporation of PGO in the membrane matrix showed a significant impact on the macroscopic properties, counterion frictional coefficient, and performance of the membrane. A well-optimized SPEEK/PGO-8 (8% PGO content, w/w) membrane showed improved conductivity (4.15 × 10–2 S cm–1) and permselectivity (87%), and excellent stabilities (thermal, mechanical, and chemical) because of cherished polymer–PGO (filler) interaction via H-bonding. The efficiency of the SPEEK/PGO-8 membrane was also evaluated for the desalination of brackish water near limiting current density (Ilim). Ion concentration polarization (ICP) was assessed by i–V curves, and below Ilim, water splitting or change in product water pH was ruled out. While above Ilim (10.5 mA cm–2), ICP was significant and could be finally tuned with applied current density for producing desalinated water with a desired pH. Furthermore, improved Ilim, high current efficiency (82.9%), and low energy consumption (7.9 kWh kg–1 of the salt removed) of the SPEEK/PGO-8 membrane during electrodialysis provide a broad current window for efficient and rapid water desalination/purification.

Functionalization of poly(vinylidene fluoride-co-hexafluoro propylene) (HFP) is made to prepared membrane for its application in fuel cell. The sulphonation of HFP membrane is carried out under control condition to maintain its stiffness and toughness of the membrane. The evidence of functionalization (sulphonation) is confirmed through different spectroscopic techniques such as NMR, FTIR, EDS mapping and UV–visible measurement and the degree of sulphonation is calculated from the integral peak area. The structural change from the usually crystallized α-phase to piezoelectric γ-phase in functionalized membrane is established through XRD studies. Mechanical and thermal stabilities of the membrane are established through universal testing machine and thermogravimetric measurements. Suitability of proton exchange membrane has been verified through their high water uptake (12%), low fuel permeability (4.43 × 10−7 cm2 s−1) and thermal stability (up to 200 °C). The proton conductivity is found to be high in functionalized membrane while its low fuel permeability and high temperature stability is very good as compared to standard Nafion membrane. Efficiency of the membrane is reported in the form of selective parameter (ratio of conductivity and methanol permeability) of value 0.78 × 105 S cm−3.s for functionalized HFP against the value of 0.81 × 105 S cm−3.s for standard Nafion 117. Moderately high open circuit voltage (0.63 V) and power density of 48.34 mW/cm2 is reported indicating very good performance of the overall membrane for direct methanol fuel cell. Therefore, direct functionalization of a polymer is a better approach for the preparation of fuel cell membrane.

A unique vapour transport cum glancing angle deposition (VT-GLAD) technique was employed to fabricate titanium dioxide (TiO2) nanowires (NWs). The NWs were grown and assembled to form the clusters. Both brookite (412) and rutile (002) phase for TiO2 was obtained from X-ray diffraction (XRD). The d spacing of ~ 1.37 A was calculated from the transmission electron microscopy (TEM) of TiO2 NWs, which corresponds to (002) crystal plane. The silver (Ag) nanoparticles (NPs) on TiO2 NWs were grown using thermal evaporation cum GLAD technique. The presence of Ag NPs on the TiO2 NWs enhanced the photoconduction as compared to bare TiO2 NWs device. The maximum photosensitivity of the Ag NPs/TiO2 NWs based device was recorded ~ 1.6 times compared to the bare TiO2 NWs based device at − 2.5 V. The Ag NPs containing device was highly UV sensitive and maximum responsivity for the device was calculated to be ~ 2.3 A/W at 370 nm. The device also possessed high responsivity rejection (RR) ratio of ~ 6.5 between UV (370 nm) and visible (450 nm) light. The Ag NPs decorated TiO2 NWs based detector also showed response to white light. The different concentration of glucose into deionised (DI) water-based solution was detected precisely under white light illumination. The normalised (light/dark) detector current/glucose concentration value was decreased from ~ 0.19 to ~ 0.05 at − 2.5 V, with an increase in glucose concentration into the solution from 40 mg/dl to 200 mg/dl.

The acid/oxidative-resistant aliphatic-polymer-based cation-exchange membrane (CEM) is urgently required for water splitting by iodine-sulfur electrochemical Bunsen process (I-S cycle). Under operating environment of I-S cycle, commercially available CEM (perfluorosulfonic acid polymers such as Nafion) exhibits excessive mass transfer via electro-osmosis and its conductivity deteriorates due to membrane dehydration, while aromatic hydrocarbon based polymers showed short lifetimes due to the oxidative degradation. Herein, we achieved partial sulfonation of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) to introduce hydrophilic character in the polymer matrix, and prepared sulphonated PVDF-co-HFP (SPVDF)/sulphonated GO (SGO) composite acid resistant CEMs with different composition for water splitting via I-S process for hydrogen production. These CEMs were extensively characterized for their morphological characteristics, ion-exchange capacity (IEC), water uptake, conductivity, and stabilities (mechanical, chemical, and thermal) in comparison with state-of-art Nafion117 membrane. About 3-fold high bound water content of suitable assessed SPVDF/SGO40 CEM (bound water content: 3.17%) in compare with Nafion 117 (bound water content: 1.04%) avoids the membrane dehydration and thus any deterioration in membrane conductivity. Iodine−sulfur (I−S) Bunsen process was successfully performed by membrane electrolysis in a two-compartment electrolytic cell (direct contact-mode) using SPVDF/SGO composite CEMs of different compositions. Theoretical and experimental values of acid produced in the anolyte and catholyte, showed good agreement. Further, relatively high current efficiency (close to 100%) for electrochemical Bunsen process using SPVDF/SGO40 CEM confirmed absence of any side reaction, while approximately 300 kJ mol-H2−1 energy was consumed to produce 1 mol of H2. In spite of low conductivity in compare with state-of-art Nafion 117 membrane, SPVDF/SGO40 composite CEM was assessed as suitable candidate for water splitting via I-S (Bunsen) process because of its low-cost nature, high bound water content and excellent stabilities in highly acidic environment attributed to the partial fluorinated segments in the membrane matrix.

Erbium doped Indium Oxide (In2O3:Er) thin films (TFs) were synthesised by spin-on technique. Secondary Ion Mass Spectrometry confirmed that Er is incorporated into the In2O3 lattice and formed an In-O-Er layer. The current–voltage loop produced a lower loop current window of ∼3.6 × 10−4 A for In2O3:Er TF based devices. The Au/In2O3:Er/Si Schottky devices have lower ideality factor (∼6) and higher barrier height (∼0.63 eV) at 300 K than Au/In2O3/Si control samples. A blue shift in the main band-gap (∼50 nm) was calculated for In2O3:Er TFs from 10 K photoresponse. The Au/In2O3:Er/Si samples show higher photosensitivity in the temperature range 10 K–300 K and maximum (∼15 times) in the UV region at 10 K as compared to the Au/In2O3/Si devices. In addition, the Au/In2O3:Er/Si devices have better UV to visible cut-off ratio (∼3 times). Excellent temporal responses were recorded for Au/In2O3:Er/Si in the UV region as compared to Au/In2O3/Si.

Bipolar membrane (BPM) was prepared by layer-by-layer casting of the cation-exchange layer (CEL; sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO), interfacial layer (IL), and anion-exchange layer (AEL; quaternized PPO) in the same solvent to achieve good adhesion. Graphene oxide-polyaniline composite (GO-PANI) was introduced in the IL of BPM as water dissociation (WD) catalyst. Under applied reverse bias, water molecules in the IL zone dissociate and generate H+ and OH– useful electrosynthesis by BPM electrodialysis (BPMED). Prepared BPM was assessed by current–voltage (i–V) curves and performance of BPMED for converting homologues carboxylates into their corresponding acid and base. Under the operating conditions in BPMED, 71–63% recovery of the different carboxylic acids was recorded with 92–97% CE and 0.90–0.98 kWh kg–1 energy consumption. Negligible co-ion leakage across the BPM also revealed its efficient nature and product (carboxylic acid) purity. Additionally, low and stable Vdiss (0.77−1....

The layer-by-layer casting technique was adopted to fabricate bipolar membranes (BPMs) comprising a cation-exchange layer (CEL), an interfacial layer (IL, phosphorylated graphene oxide (PGO) and/or quaternized graphene oxide (QGO)), and an anion-exchange layer (AEL). Under applied dc potential gradient, water molecules dissociate at the IL and generate H+ and OH–. The effect of the IL nature (PGO, QGO, and mixed PGO/QGO) on the water splitting performance of the BPM was thoroughly studied. Well optimized BPM-PGO/QGO exhibited high current efficiency (CE) and low energy consumption and was assessed to be superior in comparison with different commercial BPMs. The reported BPM showed improved water splitting performance, significant reduction in resistance, and high permselectivity (low co-ion leakage) for over 10 experimental cycles. Relatively stable performance of BPM-PGO/QGO made it industrially viable for water splitting.

Nickel ferrite fiber (NFO–F) was synthesized using the electrospinning technique and annealed at five different temperatures (500, 600, 700, 800, and 900 °C) to study its effect on crystal structure and magnetic properties. The X-Ray diffraction pattern analysis was carried out to explore its crystal structure. The morphology and microstructure of fibers were studied by employing the Field Emission Scanning Electron Microscopy technique. The crystallinity of the material increases with the increase of annealing temperature from 500 to 900 °C. The saturation magnetization of nickel ferrite fiber increases from 31.1 to 54.0 emu/g with the increase in annealing temperature. The anisotropy constant for NFO–F calculated using the Law of Approach to Saturation (LA) and it shows the highest value for 900 °C annealed sample. Hence, the hyperthermia property of NFO–NF annealed at 900 °C has been explored. The Specific Absorption Rate (SAR) of NFO–NF calculated using Linear Response Theory and the Box-Lucas models.

GeO2 thin film (TF) was fabricated by vapour deposition technique in a two zone horizontal quartz tube. Field emission-scanning electron microscopy showed the formation of 200 nm TF on the Si (100) substrate. The X-ray diffraction depicted the presence of the polycrystalline GeO2 TF. The UV–vis absorption spectrum showed humps at 3.1 eV, 4.0 eV and 5.4 eV. The band anticrossing (BAC) model is modified using the Urbach equation to understand the different transitions in the optical absorption spectrum. We have theoretically calculated the relative refractive index (r.i.) ( n r ) of the GeO2 as 1.8. The temperature dependent current (I)–voltage (V) characteristics and photocurrent of the Au/GeO2/p-Si Schottky device predicted the tunnelling of the carriers, presence of oxygen defects at the junction. The device’s temporal response indicated good photosensitivity at all temperatures and a significant increase in photocurrent was obtained as the temperature increased from 303 K to 403 K.

The high-temperature (303 K to 413 K) current conduction properties of Au/TiO2/p-Si (undoped) and Au/Er:TiO2/p-Si (doped) Schottky barrier diodes (SBDs) were analyzed. The barrier height (Фb0) increased, whereas the ideality factor (n) and series resistance (RS) decreased for these devices with increasing temperature. The activation energy as well as Richardson constant (A*) were determined from the temperature-dependent Richardson plot (R-plot). The calculated values of A* are much lower than the reported value. This behavior was clarified by assuming the barrier inhomogeneities and considering a Gaussian distribution (GD) of barrier height (BH). GD analysis modified the R-plots. The estimated standard deviation (σ0) value decreased from 0.18 (for undoped) to 0.17 (for the doped device), which indicates the reduction in barrier inhomogeneity. Also, the calculated mean values of Фb0 and A* are 1.41 eV and 871 A/(cm2K2) for undoped, 1.46 eV and 402 A/(cm2K2) for the doped device, respectively. The values of A* are much closer to the reported value of 671 A/(cm2K2) for TiO2. Therefore, it is evident that this analysis using the thermionic emission (TE) theory and considering a GD of BH elucidated the I–V characteristics of the SBDs. Other device parameters like bandgap variation with temperature, carrier concentration, Fermi energy, and RC constant were theoretically determined. Further, a unique technique has been developed to calculate the interface trap density profiles using the I–V characteristics of the devices. Hence, it is manifested that the temperature-dependent I–V characteristic can be used as a robust tool to analyze all possible vital parameters of the device.

IR- and Raman-active phonons of boron carbide and the mode Gruneisen parameters γ related are studied concerning their dependence on chemical composition, temperatures between 30 and 800 K and pressures up to ∼70 GPa. Most bulk phonons yield γ between +1.5 and - 1.5: those related to icosahedra yield γ = 0.8(3). Surface phonons are distinguished by considerably higher γ . Negative γ of chain bending modes supports the assumption that the chain center buckles out under pressure. Some striking specific mode Gruneisen parameters are explained. Pressure-dependent bond lengths suggest the reversible high-pressure phase transition to be second order.

Axial Co3O4 - TiO2 heterojunction nanowires (NWs) were synthesized by glancing angle deposition (GLAD) technique. The p-n heterojunction showed excellent rectification ratio of 2.26 × 102 at ± 3.4 V. The forward turn on voltage of 1.5 V in the dark was reduced to 1 V under white light excitation on the device. The diode showed a maximum half-wave rectification efficiency of 7.77% at 200 Hz frequency operated with maximum ±10 V. The device showed maximum peak responsivity of 4.01 A/W and internal gain of 13.1 at 380 nm wavelength. The detectivity was calculated to be 2.82 × 1011 and 1.69 × 1011 Jones and the noise equivalent power was estimated to be 14.9 and 24.8 pW at 380 and 620 nm wavelength, respectively. The device spatial response showed sharp transition with rise and fall time of ∼0.17s and 0.21s, respectively.

The La3+ modified lead free Bi 0.5 Na 0.5 TiO 3- BaTiO 3 /BNBTO solid solutions near morphotropic phase boundary [((Bi 0.94 La 0.06 ) 0.5 Na 0.5 ) 0.94 Ba 0.06 TiO 3 /BLNBTO and ((Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 ) 0.91 La 0.06 TiO 3 /BNBLTO] have been prepared by the high temperature solid state reaction method. The crystal structure of BLNBTO transfers from Rhombohedral (R3c) to pseudocubic symmetry (P4bm) with the anti-polar phase in BNBLTO, which is confirmed by the Rietveld refinement of the XRD patterns. The microstructural analysis of the samples has been carried out by the field emission electron microscopy. The temperature dependent dielectric permittivity shows the diffuse phase transition (DPT). The degree of DPT has been estimated by the modified Curie-Weiss law and, found to be 1.671 and 1.716 for BLNBTO and BNBLTO respectively. The compositional fluctuation induced relaxor antiferroelectric ordering has been confirmed by the ferroelectric hysteresis loops. The energy storage density of BNBLTO has been found to be 0.376 Jcm−3. The present work provides the role of compositional engineering to tune the physical properties of the material for technological applications.

Undoped and Erbium (Er) doped In2O3 (In2O3:Er) thin films (TFs) were deposited on p-Si (100) substrates by sol-gel spin coating technique followed by open-air annealing. Gold (Au) Schottky contact based devices showed lower ideality factor and higher barrier height for the In2O3:Er in comparison with the undoped one. The enhanced photocurrent for the In2O3:Er TFs makes it more photosensitive than undoped In2O3 TFs. The responsivity curve shows a blue shift in near band edge absorption for the In2O3:Er TFs. As a whole, there was a reduction in trap density with the incorporation of Er into In2O3 lattice and room temperature photo responsivity curves can be directly used to track the trap-related optoelectronic properties of a light-sensitive material.

The composite of BaFe12O19 (BHF) and CoFe1·75Zn0·25O4 (CZF) with different weight percentages have been synthesized by using the high energy planetary ball mill technique. The obtained powders have been characterized by employing the X-ray diffraction, Field Emission Scanning Electron Microscope, and Energy Dispersive X-ray analysis techniques. The lattice parameters and phase percentage have been obtained by the Rietveld refinement analysis of XRD peaks. The crystallite sizes of BHF are greater than the CZF. The magnetic hysteresis loops have been recorded by using the Vibrating Sample Magnetometer (VSM) for all samples. The magnetic interaction between BHF and CZF in the composite has been investigated by plotting the loop width (ΔH) versus magnetization (M). The shape of these curves between loop width versus magnetization is changed with a different weight percentage of BHF and CZF. The saturation magnetization increases with an increase in the concentration of CZF in the composites. Vegard's law is used for comparing the theoretical and experimental magnetic parameters. The squeezing in hysteresis loop at H = 0 vanishes for (55)% BHF + (45)%CZF sample below 150 K and interesting magnetic interaction between two phases has been observed.

The enhanced electronic memory performance of glancing angle deposited erbium-doped indium oxide (In2O3:Er) transparent nano-column (NCol) based metal-oxide-semiconductor (MOS) structured memory devices is reported. The fabricated MOS devices are Au/In2O3/p-Si, Au/0.26 at. % In2O3:Er/p-Si, and Au/0.48 at. % In2O3:Er/p-Si. The capacitance–voltage (C–V), conductance–voltage (G–V), C–V hysteresis, endurance, and retention properties from the cyclic current–voltage (I–V) curve of the fabricated devices were investigated in detail. The overall interface state density (Dit) for the devices at the different applied frequency (f) decreases with the increase in Er doping. The observations obtained from C–V, G–V, and Dit–f curves were theoretically explained considering a modified delta depletion model. It was found that Au/0.48 at. % In2O3:Er/p-Si does not go to inversion even at a high applied voltage. The constant capacitive memory window (MW) for Au/In2O3/p-Si is ∼1 V at the depletion region. MW increases from ∼0.6 V (sweep voltage ±6 V) to ∼2.5 V (sweep voltage ±16 V) and ∼1.4 V (sweep voltage ±6 V) to ∼6.8 V (sweep voltage ±16 V), respectively, for Au/0.26 at. % In2O3:Er/p-Si and Au/0.48 at. % In2O3:Er/p-Si. The increased MWs despite reduced Dit is explained in detail by primarily considering increased polarization switching of the In-O-Er material, asymmetric charge injection from the top electrode, and the presence of the oxygen-rich environment. The I–V hysteresis performance of the devices under a reverse bias was also improved with Er doping due to the migration of O2− inside the oxide layer. The whole analysis indicates that the gate-controlled Au/0.48 at. % In2O3:Er/p-Si MOS device is appropriate for capacitive memory applications.

Two different sets of multiferroic nanocomposites i.e., (1-x)Bi0.85La0.15FeO3-(x)BaFe12O19 with x = 0.00, 0.05, 0.10, 0.20, 0.30, 0.40, 0.50 and 1.00 have been synthesized by the solid-state reaction method and high energy planetary ball mill techniques. The peaks in the XRD patterns can be indexed to R3c crystal symmetry of Bi0.85La0.15FeO3 and P63/mmc crystal symmetry of BaFe12O19. It suggests the absence of any major chemical reaction between the two phases. Moreover, it is assumed thatBi0.85La0.15FeO3 and BaFe12O19 crystal symmetries are present in the composite independently. Magnetic properties have been improved significantly due to the incorporation of BaFe12O19 in the composites. Vegard's law suggests that the experimentally observed magnetizations are higher than that of theoretically calculated value. The difference between the theoretical and experimental magnetization as well as the anomaly in the magnetic hysteresis have been explained by considering the magnetic interaction correlation length between Bi0.85La0.15FeO3 and BaFe12O19 magnetic phases. The hysteresis loop width (ΔH) versus M plots has been introduced to understand the magnetic interaction (exchange bias) between Bi0.85La0.15FeO3 and BaFe12O19. Magnetocrystalline anisotropy increases with the increase in the percentage of BaFe12O19 in the composite.

The Rietveld refinement of XRD patterns reveals the crystallization of all the materials (BaFe12-xZnxO19 for x = 0.0, 0.2, 0.4, and 0.6) to hexagonal symmetry with space group P63/mmc. The lattice strain created in the crystal due to the ionic size mismatch of Zn and Fe. The Law of Approach (LA) to saturation method is employed to obtain the saturation magnetization (Ms) and magnetocrystalline anisotropy constant (K1) from M−H hysteresis loop. The maximum saturation Magnetization (Ms) and minimum coercivity are found to be for BaFe11·8Zn0·2O19 (i.e., x = 0.2). The magnetocrystalline anisotropy constant (K1) reduces with the increase in temperature. The magnetic properties and magnetic crystalline anisotropy in Zn modified barium hexaferrite have been explained by considering the strain in the lattice site and superexchange interaction.

Magnetic properties of the material with more than two crystal phases are found better as compared to that of single crystal phase material. Hence, nanocomposites with different weight percentages of Barium Hexaferrite (BaFe12O19/BHF) in Barium Titanate (BaTiO3/BTO) matrix have been prepared. The X-ray diffraction patterns of BHF, BTO and nanocomposites reveal the absence of other secondary crystal phases. The Raman spectra analysis supports to the XRD patterns analysis. The presence of both BHF and BTO crystal phases in the nanocomposites have been confirmed by the high resolution transmission electron microscopy. Interestingly, the nanocrystalline BTO exhibits weak ferromagnetic behavior. Magnetic interaction between BTO and BHF in the bi-magnetic BTO-BHF composite has been observed.