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The fabricated Mg-doped ‘α-Fe2O3’-based HEC generates a short circuit current of ∼40 mA and power output of 36 mW. This is a promising device for producing green energy, and opens new avenues for alternative sources of green energy.

Self-assembled ZnO nanoflakes grown at the zinc electrode of a hydroelectric cell by water splitting have been analyzed.

Magnesium ferrite (MgFe2O4) nanorods and magnesium ferrite/polythiophene (MgFe2O4/PTh) composites have been fabricated by sol–gel and in-situ emulsion polymerization approach to investigate EMI (electromagnetic interference) shielding activity in the X-band region. The encapsulation of MgFe2O4 nanorods by conducting PTh decreased the coercivity and improved the conductivity of the composites. The composite with a maximum loading of MgFe2O4 nanoparticles (MP-21; MgFe2O4:PTh = 2:1) displayed superior magnetic moment (23.27 emu/gm) and coercivity (0.023 kOe). In addition, the composite (MP-21) exhibited the highest SE (shielding effectiveness) of − 40.17 dB at 10.29 GHz by 1 mm thick pellet for X-band region (8.2–12.4 GHz). The excellent shielding behavior of the composite is attributed to the synergistic effect of these two moieties resulting in the high dielectric and magnetic loss. Moreover, the porous and rod-like morphology of these composites further induces microwave absorption ability. These results revealed that MgFe2O4/PTh composite showed the maximum EMI shielding property, which can find potential application as a lightweight, high-performance EMI shielding material.

In this work, lead-free (1-x) Ba0.85Ca0.15Zr0.1Ti0.9)O3–xCoFe2O3 (BCZT-CFO, x = 00, 0.2,0.8 and 1) multiferroic composites have been prepared by chemical solution technique and sintered at 1300 °C. The article is focused on a systematic study of phase dominance effect on structure, microstructure, dielectric, magneto-dielectric, magnetic, electric, and magneto-electric properties of the BCZT-CFO composites. The XRD study confirms perovskite phase in BCZT, cubic spinal phase in CFO and mixed structural evolution in composite samples without any traceable secondary phase formation. William-Hall equation has been used to evaluate strain kinetics in pure and composite samples. The scanning electron micrographs show dispersion of smaller BCZT grains in larger CFO grains matrix. The dense microstructure has been observed for composite sample with ferrite phase dominance. The room temperature dielectric study reveals frequency-dependent dielectric dispersion characteristics for composites and pure CFO. The enhanced dielectric properties are observed for composite sample with ferroelectric phase dominance. The room temperature magneto-dielectric behavior has been observed for lead-free multiferroic composites. Under magnetic study, observed typical ferromagnetic M-H hysteresis loop reveals presence of long-range ferromagnetic ordering in pure CFO as well as in composite samples. The highest value of Ms ~ 38.2 emu/g and Mr = 1.2 emu/g has been measured for ferrite phase dominant composite sample. Higher coercive field Hc value has been observed for composite with ferroelectric phase dominance. Leakage current characteristic has been investigated at and above room temperature for prepared samples. The composite with ferrite phase dominance has shown higher leakage current characteristics. The enhanced magento-electric coupling coefficient has been measured for composite with higher ferrite phase concentration.

This article describes preparation of Barium (Zirconium) Titnate (BaZr0.2Ti0.8O3) ceramics by the sol–gel technique and its structural, dielectric, ferroelectric, and piezoelectric properties investigated with sintering temperature variation. The phase and microstructure analysis of the sintered ceramics was carried out by X-ray diffraction method (XRD) and scanning electron microscopy (SEM), respectively. XRD analysis revealed structural transformation from cubic to tetragonal phase with increase in sintering temperature. Dielectric properties have been measured with variation of frequency up to 1 MHz and with temperature up to 200 °C. The BZT ceramics exhibit diffuse phase transition with normal ferroelectric behavior. Hysteresis loop measurements disclosed that BZT ceramics have good ferroelectric nature with saturation at higher applied electric fields. Leakage current density show negative temperature coefficient resistance (NTCR) behavior. The highest value (261 pC/N) of piezoelectric coefficient (d33) has been obtained for BZT ceramic sintered at 1400 °C and revealed that ceramics have great potentials for electronic industry based on sensor technology.

An electrochemical biosensor was developed to determine formaldehyde (HCHO) adulteration commonly found in food. The current responses of various electrodes based on multiwalled carbon nanotubes (CNTs) and synthesized nanocomposite (CNT–Fe3O4) were measured using cyclic voltammetry. The nanocomposite based biosensor shows comparatively high sensitivity (527 µA mg/L−1 cm−2), low detection limit (0.05 mg/L) in linear detection range 0.05–0.5 mg/L for formaldehyde detection using formaldehyde dehydrogenase (FDH) enzyme. In real sample analysis, the low obtained RSD values (less than 1.79) and good recovery rates (more than 90%) signify an efficient and precise sensor for the selective quantification of formaldehyde in orange juice. The developed biosensor has future implications for determining formaldehyde adulteration in citrus fruit juices and other liquid foods in agri-food chain to further resolve global food safety concerns, control unethical business practices of adulteration and reduce the widespread food borne illness outbreaks.

The present study was conducted from July 1, 2020 to September 25, 2020 in a dedicated coronavirus disease 2019 (COVID‐19) hospital in Delhi, India to provide evidence for the presence of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) virus in atmospheric air and surfaces of the hospital wards. Swabs from hospital surfaces (patient's bed, ward floor, and nursing stations area) and suspended particulate matter in ambient air were collected by a portable air sampler from the medicine ward, intensive care unit, and emergency ward admitting COVID‐19 patients. By performing reverse‐transcriptase polymerase chain reaction (RT‐PCR) for E‐gene and RdRp gene, SARS‐CoV‐2 virus was detected from hospital surfaces and particulate matters from the ambient air of various wards collected at 1 and 3‐m distance from active COVID‐19 patients. The presence of the virus in the air beyond a 1‐m distance from the patients and surfaces of the hospital indicates that the SARS‐CoV‐2 virus has the potential to be transmitted by airborne and surface routes from COVID‐19 patients to health‐care workers working in COVID‐19 dedicated hospital. This warrants that precautions against airborne and surface transmission of COVID‐19 in the community should be taken when markets, industries, educational institutions, and so on, reopen for normal activities.

The present work explains the structural analysis of Se-rich (Ge20Se80)90Sb10 glassy system prepared using melt-quenching technique. Thin films of (Ge20Se80)90Sb10 are prepared on well-cleaned glass substrates using vacuum evaporation technique. All the structural characterizations for (Ge20Se80)90Sb10 system are performed at room temperature (298 K). XRD spectrum verifies the amorphous nature of as-prepared sample with the possibility of short-range ordering in the sample. The spherical granular morphology of the thin film has been studied using FE-SEM. The purity and the precise composition of the thin films are determined using EDS. The distribution of the constituent elements is investigated using elemental mapping. Raman studies help in understanding the basic structural units comprising the prepared sample.

The scarcity of energy is a major constraint in economic growth of any country. Day-by-day increasing demand of energy is deteriorating our environment quality. In order to combat environmental pollution threat, clean and green energy sources are critically enforced. Naturally occurring relative humidity has been probed in the form of humidity sensor. Highly resistive ceria doped magnesium ferrite thin film exhibited a colossal decrease in resistance of the order of 107 with only environmental humidity change from 10 to 95%RH. Such huge colossal humidoresistance of magnesium ferrite paved way to research on energy harvesting from water molecule dissociation at room temperature. Nanoporous and oxygen-deficient lithium substituted magnesium ferrite has been processed to make it highly sensitive towards water molecule dissociation into OH− and H+ ions. Electrochemistry has been adapted to collect these dissociated ions by two dissimilar electrodes zinc anode and silver inert cathode. The redox reactions on these electrodes generated power and the device is named ‘Hydroelectric Cell’. The working principle of hydroelectric cell has been also validated in other ferrite and different metal-oxides such as Fe3O4, Fe2O3, SnO2, TiO2, ZnO, Al2O3, MgO and SiO2. The redox reactions at electrodes of hydroelectric cell provide eco-friendly and commercially viable byproducts hydrogen and zinc hydroxide.

Ozone (O3), oxides of nitrogen (NOx), and carbon monoxide (CO) were monitored at CSIR National Physical Laboratory, New Delhi, during May and October, 2014. One-hour O3 concentrations exceeding more than 120 ppb were observed for 9 days in May and 16 days in October months with concurrent high NOx and CO values. The higher ozone episodes in October 2014 as compared to May 2014 may be due to contribution of biomass burning. The nitrogen oxide (NO), nitrogen dioxide (NO2), O3, and the photolysis rate of NO2 (i.e., JNO2) values of May and October, 2014, were used to evaluate the photo-stationary state ratio (or Leighton ratio, ϕ) for clear sky conditions. Leighton ratio ranged from 0.4 to 2.6 (average values 0.89 ± 0.4) for May 2014 and from 0.3 to 3.6 (average value 1.01 ± 0.52) for October 2014. The observed NOy values in October 2014 indicated the production of O3 through hydrocarbon-sensitive O3 chemistry. The sum of reactive nitrogen species’ (i.e., NOy) mixing ratios recorded during October 2014 varied from 259.4 to 10.4 ppb with an average value of 80.5 ± 39 ppb. The averaged diurnal ratio of NOx–NOy of > 0.3 indicated the presence of freshly emitted pollutants.

Due to the similar electrochemical properties to graphene oxide (GO), graphene quantum dots (GQDs) are considered as a highly potential candidate for designing an electrochemical biosensor. In this report, GQDs were synthesized having an average diameter of 7 nm and utilized for the fabrication of an electrochemical immunosensor for the detection of food toxin, aflatoxin B1 (AFB1). An electrophoretic deposition technique was utilized to deposit the chemically synthesized GQDs onto indium tin oxide (ITO)-coated glass substrate. Further, the monoclonal antibodies of AFB1 were covalently immobilized onto deposited electrode GQDs/ITO using EDC-NHS as a crosslinker. The structural and morphological studies of GQDs and conjugated anti-AFB1 with GQDs have been investigated using UV-visible spectroscopy, photoluminescence spectroscopy, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy techniques, etc. The electrochemical impedance spectroscopy and cyclic voltammetry measurements were carried out for electrical characterization and biosensing studies. This simple monodisperse GQDs-based platform yields heterogeneous electron transfer (97.63 × 10−5 cm s−1), the time constant (0.005 s) resulting in improved biosensing performance. The electrochemical immunosensor shows high sensitivity 213.88 Ω (ng mL−1)−1 cm−2. The limit of detection for standard samples and contaminated maize samples was found to be 0.03 ng mL−1 and 0.05 ng g−1, respectively, which is lower than the maximum acceptable limit according to the European Union. This result indicates its potential application for aflatoxin B1 detection in food contents.

In the present study, trace gases (NH3, NOx, CO and SO2), PM2.5 and meteorological parameters were carried out at 5 different monitoring sites [CSIR-National Physical Laboratory, New Delhi and other 4 air quality measurements (AQMS) sites (Anand Vihar, Mandir Marg, Punjabi Bagh and R.K. Puram) of Delhi Pollution Control Committee (DPCC)] of megacity Delhi, India, from January 2013 to December 2015 to estimate the spatio-temporal variation of pollutants over Delhi. The results showed large spatial and seasonal variations in mixing ratios of ambient trace gases and PM2.5 concentration over Delhi. The average mixing ratios of NH3, NO, NO2, CO and SO2 were 53.4 ± 14.9 ppb, 42.0 ± 14.6 ppb, 39.6 ± 13.0 ppb, 1.9 ± 0.4 ppm and 4.3 ± 1.0 ppb, respectively, whereas average concentration of PM2.5 was 136.2 ± 49.6 µg m−3 during the entire study period. All the trace gases and PM2.5 showed maxima during winter season followed by summer and monsoon seasons at all the sites. The 24-h average mixing ratios of the trace gases (NH3, NO, NO2, CO and SO2) and PM2.5 were recorded higher when compared with other sites of the country. The concentration of PM2.5 is breaching the prescribed standard limit of National Ambient Air Quality Standards (NAAQS) of India.

Solar UV radiation reaching the Earth's surface is known to have various effects on human health and on the ecosystem. Ground-based measurements of surface UV radiation are spatially sparse and in many cases do not provide long time series. Higher spatial coverage can be provided by measurements from satellite based instruments, but these measurements need to be compared to ground-based measurements of sufficient quality before they can be used in health and ecosystem applications. Here, we compare the measurements of surface solar UV radiation in UVA (315–400 nm) and UVB (280–315 nm) bands with the satellite retrievals (CERES) and validate the latter at an urban location, Delhi, India. We have also used MODIS-retrieved aerosol optical depth (AOD) and cloud optical depth (COD) data to see the effect of atmospheric opacity on UV radiation. Ground-based measurements of UVA and UVB were performed from 01 October, 2012 to 30 September, 2015. Correlations between daily surface measurements and CERES-derived surface UV fluxes showed very good agreement (r ∼ 0.92–0.93) over Delhi. We found a negative correlation between UV fluxes and AOD over Delhi during all seasons. A unit increase in AOD leads to a decrease of ∼4–5 Wm-2 in UVA and ∼0.09–0.14 Wm-2 in UVB over Delhi. The trend analysis from monthly mean CERES-derived UV fluxes for 17 years data reveals that UVA and UVB are decreasing ∼0.07 Wm-2 yr−1 and 0.003 Wm-2 yr−1, respectively with AOD increase (∼0.005 yr−1) over Delhi. The simultaneous increase in aerosol loading with decrease in UV fluxes at the surface may be explained as a masking effect of ever increasing pollution on surface UV radiation over Delhi. Our results show ∼10% and ∼20% decrease (with respect to mean) in UVA and UVB surface fluxes, respectively during last 17 years.

For source identification, a field campaign involving simultaneous sampling of particulate matter (PM10) was conducted at eight sampling sites in the Indian mainland during winter 2014. The sampling sites include Delhi (upper IGP), Lucknow (middle IGP), and Kolkata (lower IGP) in the Indo-Gangetic Plains (IGP); Mohal-Kullu and Darjeeling in the Indo-Himalayan Range (IHR). In addition, Ajmer, located upwind of the IGP in NW-India and Giridih and Bhubaneswar, in the downwind to the IGP has also been chosen. To characterize the sources of the ambient PM10, stable isotope ratios of carbon (δ13CTC) and nitrogen (δ15NTN) for the total carbon (TC) and total nitrogen (TN) fractions have been considered. Ancillary chemical parameters, such as organic carbon (OC), elemental carbon (EC), and water-soluble ionic components (WSIC) mass concentrations are also presented in this paper. There was very small variation in the daily average δ13CTC ratios (− 24.8 to − 25.9‰) among the sites. Comparison with end-member stable C isotopic signatures of major typical sources suggests that the PM10 at the sites was mainly from fossil fuel and biofuel and biomass combustion. Daily average δ15NTN ratios were not observed to vary much between sites either (8.3 to 11.0‰), and the low δ15NTN levels also indicate substantial contributions from biofuel and biomass burning of primarily C3 andC4 plant matter.

Traditionally, the atmospheric particle composition is analyzed using destructive methods. In general, the destructive methods lead to the destruction of the samples, higher cost of the analysis and larger analysis time. In view of aforesaid, in current work, we present a method for the non-destructive analysis of atmospheric particles using open path-Fourier transform infrared spectroscopy (OP-FTIR). The developed method has been used for the measurement of ammonium and sulfate in atmospheric particles without destroying the samples. Here, we targeted the said species because of their relative importance for air pollution episode formation. Particulate sulfate plays a major role in formation of haze. However; particulate acidity is an important factor in this process, which is governed by particulate ammonium concentration. Therefore, both SO42− and NH4+ are important as far as atmospheric chemistry of haze formation is concerned. In the present study, the qualitative and quantitative estimation of ammonium and sulfate ions in PM2.5 (particulate matter with aerodynamic diameter less than 2.5 µm) was carried out using OP-FTIR with the developed method. The seasonal average concentration of NH4+ and SO42− were measured to be 12.00 ± 5.80, 31.71 ± 12.71 µg/m3 respectively for winters, 3.00 ± 0.85 and 8.00 ± 2.28 µg/m3 respectively for summers and 2.60 ± 1.90 and 7.00 ± 5.21 µg/m3 respectively for monsoon season. The observed results are found to be in good agreement with that of other studies using destructive methods.

In the present study, we have investigated the spatio-temporal variation in concentrations of PM2.5 and its chemical constituents [organic carbon, elemental carbon, water-soluble organic carbon, levoglucosan, and water-soluble inorganic ions, organics] during pre-Diwali, Diwali, and post-Diwali days (13-30th October 2017) in Delhi. PM2.5 has been collected from seven strategic locations spread across the city. The massive burning of firecrackers during the Diwali festival give rise to remarkably high concentrations of ambient particulate matter (PM), organics, trace gases, and elements. Such undesirable mass loading of air pollutants over a short period degraded ambient air quality for several days after the festival, prompted us to investigate the impact of short-term air quality degradations events. The average concentration of PM2.5 over Delhi during pre-Diwali days, Diwali day and post-Diwali days have been recorded 169 ± 51 μg/m3, 521 ± 307 μg/m3 and 193 ± 61 μg/m3, respectively with maximum observed at site 3 (903 μg/m3) and minimum at site 7 (141 μg/m3). The mass concentrations of the markers for biomass and firecrackers burning (OC, levoglucosan, WSOC, and K+, etc.) and mass ratios showed a significant increase in trend during the festive period.

Here in this article synthesis of lead-free magnetoelectric composites (1-x) Ba0.85Ca0.15 Ti0.9Zr0.1)O3 - xCoFe2O3 (BCTZ-CFO, x = 0.4, 0.5, and 0.6) is reported. Structural, magnetic, dielectric, magnetodielectric and magnetoelectric properties of lead-free BCTZ-CFO composites sintered at higher sintering temperature have been systematically investigated. The piezoelectric (ferroelectric) phase has been synthesized using the sol–gel route, while Metallo-organic decomposition (MOD) route was employed to prepare piezomagnetic (ferrite) phase. The structural and microstructural properties were studied using X-Ray diffraction and Scanning electron Microscope respectively acknowledged the presence of two distinct phases as ferrite and ferroelectric in composite samples. The dense microstructure and larger average grain size were observed for samples with higher ferrite phase content. Long-range magnetic order was observed under magnetic study for all-composites. The magnetic properties enhanced for composites prepared with higher ferrite phase content. Dielectric properties were studied at room temperature and enhanced dielectric constant has been observed for samples with higher ferroelectric phase content, while minimum dielectric loss was observed for sample with 50/50 ferrite/ferroelectric phase composition. The magnetodielectric response has been also investigated for all ME composites. Leakage current characterization has been also discussed at and above the room temperature. The magneto-electric coupling response was measured of all composites. The higher value of magneto-electric coupling coefficient has been observed for 0.5BCTZ-0.5CFO composite due to maximum possible ferrite-ferroelectric hetero-structure phase contact area.

Estimation of the direct radiative forcing (DRF) by atmospheric particles is uncertain to a large extent owing to uncertainties in their morphology (shape and size), mixing states, and chemical composition. A region-specific database of the aforementioned physico-chemical properties (at individual particle level) is necessary to improve numerically-estimated optical and radiative properties. Till date, there is no detailed observation of the above mentioned properties over Kanpur in the Indo-Gangetic Plain (IGP). To fill this gap, an experiment was carried out at Kanpur (IITK; 26.52°N, 80.23°E, 142 m msl), India from April to July, 2011. Particle types broadly classified as (a) Cu-rich particles mixed with carbon and sulphur (b) dust and clays mixed with carbonaceous species (c) Fe-rich particles mixed with carbon and sulfur and (d) calcite (CaCO3) particles aged with nitrate, were observed. The frequency distributions of aspect ratio (AR; indicator of extent of particle non-sphericity) of total 708 particles from April to June reveal that particles with aspect ratio range >1.2 to ≤1.4 were abundant throughout the experiment except during June when it was found to shift to high AR range, >1.4 to ≤1.6 (followed with another peak of AR i.e. >2 to ≤2.4) due to dust storm conditions enhancing the occurrence of more non-spherical particles over the sampling site. The spherical particles (and close to spherical shape; AR range, 1.0 to ≤1.2) were found to be

This study investigates the seasonal distribution of inorganic aerosols in Central New Delhi and identifies their potential source regions using concentration weighted trajectories (CWTs). Secondary inorganic aerosols ( $$\hbox {NO}_{3}^{-}$$ , $$\hbox {SO}_{4}^{2-}$$ , $$\hbox {NH}_{4}^{+})$$ are the largest contributors to fine particulate matter in New Delhi, India. The concentrations of secondary inorganic aerosols showed very distinct seasonal patterns with higher concentrations in winter and post-monsoon seasons. Inorganic ions $$\hbox {Ca}^{2+}$$ , $$\hbox {Mg}^{2+}$$ and $$\hbox {K}^{+}$$ were also examined to understand their temporal trends. The primary aerosols were found to have smaller diurnal differences than secondary aerosols. The higher coefficient of divergence for secondary aerosols indicated a significant difference in their chemistry and/or meteorology during daytime and night-time, respectively. The backward trajectory analysis revealed the advection of ionic species from distant sources responsible for their significant seasonality. The highest concentrations of $$\hbox {K}^{+}$$ during the post-monsoon season were mainly influenced by air masses arriving from Punjab and Haryana regions resulting from the prominent agricultural crop residue burning in these areas. CWT also identified the Thar Desert and Punjab as potential regions for enhanced levels of $$\hbox {Ca}^{2+}$$ and $$\hbox {K}^{+}$$ , respectively. Also, the brick kilns located in western UP were observed as the major potential sources for $$\hbox {NO}_{3}^{-}$$ and $$\hbox {SO}_{4}^{2-}$$ .

Multiferroics and diluted magnetic semiconductors (DMSs) might hold the future for the ultimate spintronic devices. In the present chapter, we review the spintronic multiferroic systems based on perovskite BaTiO3 (BTO) and DMS ZnO nanostructures. We also focus on the chemical routes that synthesized multiferroic and DMS nanostructures and thin films. We discuss, in particular, the mechanism to the existence of ferromagnetism and ferroelectricity in perovskite BTO and distortions of the lattice structure, and how this can promote magnetoelectric (ME) responses. We have discussed a comparative study that report multiferroicity in transition metal (TM) substituted BTO nanoparticles for which the TM ions influenced both nanosize and lattice distortion of TiO6 octahedra. The room-temperature magnetic behavior of multiferroic BTO is discussed with antiferromagnetic interactions, which is strengthened by changing the doping level from TM and rare earth (RE) ions. The multiferroicity and polarization of BTO depend upon the impurity ions, lattice distortion, nanostructures, lone-pair electrons, charge ordering, Dzyaloshinskii–Moriya interactions. The relative permittivity of BTO/NiFe2O4 composite is decreased with applied dc magnetic field that can induce negative magnetodielectric effect which is the combination of spin pair correlation of neighboring spins and the coupling constant. By reducing the clamping effect in multiferroic composite and thin films, ferroelectric domain modification and distinct magnetization change proportional to different interfacial area around the BTO phase transition, which may pave the way to introducing ME coupling at nanoscale. It has potential in high-density multistate memory devices. The defects-assisted ferromagnetism due to bound magnetic polarons in TM and RE ions into ZnO nanostructures has been investigated. It results into antiferromagnetic f–d transitions. Using density functional theory, we have shown the occupancy of RE and TM ions (replacing Zn atoms) in the wurtzite ZnO structure.

Here, we report the structural, dielectric, ferroelectric, piezoelectric and magnetic properties of ME composites of Lead Zirconate Titanate (PZT) and Cobalt ferrite (CF) with compositional formula (1−x) PbZr0.55Ti0.45O3 + (x) CoFe2O4, (x = 0.00, 0.05, 0.10, 0.15 and 1.00 by weight). The samples were synthesized by conventional solid state reaction. The formation of perovskite tetragonal and spinel structure in the composites are confirmed by X-ray diffraction studies. Microstructural study of all samples was done by SEM analysis and average grain size was also calculated. The dielectric properties of samples were studied as a function of frequency and as a function of temperature (30°C – 500°C) respectively. P-E hysteresis loop at room temperature and piezoelectric coefficient were measured to study the ferroelectric and piezoelectric properties. To confirm the ferromagnetic behavior of the composites M-H hysteresis loop measurement was carried out. The Magnetoelectric voltage coefficient (dE/dH)...

Growing world population and rapid economic growth are making additional demands on global energy requirement. Carbon dioxide emission has peaked at 32.2 Gt/year and is expected to be at 43 Gt/year by 2016. Such huge emission of carbon dioxide has adverse effect on global climate change. Greenhouse gas emissions of 30% is being generated by the electricity sector followed by 26% from the transportation sector. A huge share of magnetic materials are being used in automotives, transformers, and the power sector, which demands special attention to a new class of magnetic materials. There are two possibilities to reduce deadly air pollution: one is to make energy efficient machines and the other is to explore new green energy sources to provide secure energy supplies. Energy generation focus has also shifted more toward alternative natural resources, such as solar energy, wind energy, bio energy, ocean energy, etc. Use of renewable alternative sources can save money, protect the environment, and ensure clean energy for future generations. Solar energy would yield a never-ending energy supply but the difficulty associated with it is to convert solar energy in an efficient and cost-effective way. The improvement in efficiency of wind turbines demands an increase in height and size that would result in mechanical stresses on the gearbox, blades, and tower.

Pb1-xSrx(Fe012Ti0.988)O3 (PSFT) nanoparticles were prepared by a chemical synthesis using polyvinyl alcohol as surfactant. X-ray diffraction pattern has been used to analyze the phase structure and average particles size. Transmission electron microscopy is used to confirm the nano size of the PSFT particles. The magnetoelectric (ME) coupling is observed at room temperature by measuring the ME coefficient (αE) as the function of applied dc magnetizing field under the influence of ac magnetic field of 2 Oe and frequency 800 Hz. The maximal value of αE is observed in PSFT3. The ME coupling is also studied by observing the variation of polarization hysteresis measured in the presence of zero and 0.2 T of external magnetic field.

This work reports the exploitation of nanocrystalline Ni

In the present work BaFe12O19 nano-hexaferrite had been synthesized by sol-gel method and then characterized for its structural, electric, dielectric and magnetic properties. X-ray diffraction studies confirmed the hexagonal structure of the prepared nanohexaferrite with no secondary phase and the particle size was found to be of the order of 49 nm. Further, the morphology of the sample has been studied by using transmission electron microscopy (TEM). A high value of the DC resistivity (5.5 × 10 6 Ω cm), has been obtained at room temperature. The dielectric properties such as dielectric constant (e'), dielectric loss tangent (tan δ) and ac electrical conductivity (σac) are investigated as a function of frequency. The dielectric constant and loss tangent are found to be decreasing with the increase in frequency while ac electrical conductivity is observed to be increasing with the increase in frequency. The dielectric properties have been explained on the basis of Maxwell-Wagner's two-layer model and hopping of the charge. The magnetic properties such as initial permeability (µi) and relative loss factor (RLF) have been investigated as a function of frequency in the range 75 kHz to 30 MHz .Fairly constant value of initial permeability and low values of RLF of the order of 10 -4 over a wide frequency range are the cardinal achievements of the present work. The room temperature M-H study shows that present nanohexaferrite has high value of coercivity (2151.3 Oe) and high saturation magnetization (32.5 emu/gm), which make present nanohexaferrite very suitable for magnetic applications. The M-T study shows that prepared nano-hexaferrite has high Tc (746 K). Copyright © 2014 VBRI press.

A scheme to finish workpiece surface in nanometer range and obtain defect free surface using bidisperse magnetorheological polishing fluid (MRPF) by ball end magnetorheological finishing (BEMRF) tool is presented. Bidisperse MRPF consist of micron size CS and HS grade of carbonyl iron powder (CIP) with different volume fraction combinations within 20 vol.% magnetic solid contents, 25 vol.% SiC abrasives and 55 vol.% base fluid. Vibration sample magnetometer (VSM) has been used to study the magnetization of magnetic abrasives. Maximum magnetization has been found for CIP of 16 vol.% CS grade, 4 vol.% HS grade and 25 vol.% SiC abrasives. Magnetorheological behavior of bidisperse MRPF was evaluated using magnetorheometer. Performance of MRPF was evaluated by steady state rheograms in magnetic field strength. The yield strength of MRPF was found maximum at CIP of 16 vol.% CS grade, 4 vol.% HS grade, 25 vol.% abrasives and 55 vol.% base fluid. After characterization, experiments were performed with BEMRF tool ...

This study examined structural, optical and magnetic properties of ITO (In0.95Sn0.05)2O3 and Cu doped ITO (In0.90Sn0.05Cu0.05)2O3 nanoparticles synthesized by solid state reaction method. The synthesized nanoparticles were subjected to structural, optical and magnetic studies. The structural properties of the nanoparticles were carried out using XRD, Raman, FT-IR characterization techniques. Optical properties of the samples were studies using UV-Vis-NIR spectrophotometer. The magnetic measurements were carried out using vibrating sample magnetometer. The ITO (In0.95Sn0.05)2O3 nanoparticles exhibited room temperature ferromagnetism with clear hysteresis loop. The strength of magnetization decreased in Cu doped ITO (In0.90Sn0.05Cu0.05)2O3. The ITO nanoparticles were also exhibited ferromagnetism at 100 K with a magnetic moment of 0.02 emu/g.

Lead free (Na0.5Bi0.5) 0.99La0.01Ti0.988 Fe0.012O3 (NBLTF) system has been synthesized by sol gel method without and with 2 mol% excess of Na and Bi. X-ray diffraction patterns of NBLTF samples confirm perovskite structure having rhombohedral R3c phase symmetry. Metal oxide band observed at ~ 629 cm−1 wavnumber in FTIR spectra also confirm formation of perovskite phase in samples. Microstructural analysis exhibits dense crystal growth having better grains connectivity for NBLTF sample with 2 mol% excess Na/Bi which is supported by room temperature DC resistivity measurements. Dense crystal growth and low leakage current with 2 mol% excess Na/Bi is reported to improve multiferroic properties of NBLTF sample and provides new insight to explore single phase lead free multiferroic system.

In the present work, the self-assembly of Co 2+ and Fe 3+ doped SnO2 nanoparticles (Co and Fe = 5 mol% each) into nanorods by co-doping of Ce 3+ (4 mol%) ions is studied. The nanorods are prepared by a chemical route using polyvinyl alcohol as surfactant with the composition Sn0.91Co0.05Ce0.04O2 (SCC54) and Sn0.91Fe0.05Ce0.04O2 (SFC54). The X-ray diffraction (XRD), transmission electron microscopy (TEM), magnetic and electrical measurements are used to characterize these nanorods. The XRD pattern show the tetragonal rutile and polycrystalline nature of SnO2 nanorods which is also confirmed by TEM. The TEM images exhibit that the diameter of SCC54 nanorods lie in the range of 15-20 nm, length~100-200 nm whereas for SFC54 specimen, diameter ~5-15 nm and length ~50-100 nm. In our previous work, we fabricated Co and Fe (3 and 5 mol% each) doped SnO2 nanoparticles which exhibited high ferromagnetism. It is observed that on Ce 3+ co-doping, nanoparticles assembled themselves into rod like structures and the values of saturation magnetization and dielectric properties have further enhanced. Thus the nature and the concentration of dopants are found to play crucial role in tuning the morphology, magnetic and electrical properties of nanostructures. The values of saturated magnetization (Ms) are 1.14 and 0.14 emu/g and coercive field are 112 and 42 Oe, in SCC54 and SFC54 specimen, respectively, at room temperature. The variation in dielectric behavior is attributed due to the interface polarization. However, in lower frequency regime, the decreasing trend of dielectric permittivity with increasing frequency is explained by the Maxwell-Wagner theory and Koops’ model, whereas, in higher frequency region, the resonant behavior is observed due to nano size effect. Copyright © 2012 VBRI Press.

In the present work, structural, microstructural and magnetoelectric (ME) coupling of multiferroic Ba(Fe0.01Ti0.99)O3 (BFT1) nanowires have been studied. BFT1 nanowires were prepared by a hydrothermal method with reaction temperature 180 o C for 48 hours. The X-ray diffraction shows that BFT1 is polycrystalline with cubic phase. The calculated value of distortion ratio (c/a) is ~ 1. No impurity or extra phase is observed. The micrographs by transmission electron microscopy reveal nanowires like structure of BFT1with diameter lie in the range of ~ 40 - 50 nm and length greater than 1.5 μm. The ME coefficient measurement shows that the ME coupling under the effect of both ac and dc bias. It shows strong dependence on ac and dc bias applied field. The value of linear coefficient (α) called ME coefficient is calculated as ~ 16 mV/Oecm at a fixed frequency of 850 Hz. This ME coefficient α corresponds to induction of polarization by a magnetic field or of magnetization by an electric field. The observed optimum dc bias field at which the maximum magneto-electric coupling occurs is ~ 750 Oe. The magnetization hysteresis shows strong ferromagnetism. Copyright © 2012 VBRI Press.

We have synthesized La1-xSrxMnO3 (with x=0.3, 0.33 & 0.4) perovskite nanoparticles using mild sol-gel technique at low temperature and thereby studied the effect of nanosize on magnetoresistance. These samples were characterized using TGA/DSC, XRD, TEM, FTIR and temperature dependent magnetoresistance (MR) measurements. Powder X-ray diffraction (XRD) result confirms the formation of pure crystalline phase with rhombohedral symmetry in R-3C space group. Crystallite size increases with increase in Sr concentration. TEM analysis further supports the nanosized particles in the samples which lie in the range of 20-30 nm. Fourier transform infrared (FTIR) spectroscopy shows a broad peak at 615 cm -1 for all the samples gives an evidence for the formation of metal oxygen bond organized in to MnO6 octahedral. The steep change in magnetoresistance (MR) at low field at low temperature is observed which is attributed to the alignment of the spins, while in the high field MR is due to the grain boundaries effect at low temperature. In the series studied, 33% Sr doped sample shows higher MR both at low temperature (-17.15) and room temperature (-3.07) than their counter parts. Copyright © 2012 VBRI Press.

O1 gene based 24-mer single stranded deoxyribonucleic acid probe (ssDNA) has been immobilized onto sol-gel derived nanostructured zirconium oxide (NanoZrO2) film fabricated onto indium-tin-oxide (ITO) coated glass plate to detect Vibrio cholerae. The X-ray diffraction and Atomic Force Microscopy techniques have been used to characterize the nanostructured ZrO2 (particle size of ~ 30–40 nm) and the ssDNA/ZrO2 bioelectrode. The hybridization of ssDNA/ZrO2 bioelectrode with the complementary and genomic DNA has been investigated using differential pulse voltammetry. The results of electrochemical studies suggest that electro-active and cationic NanoZrO2 provides an effective surface to bind with the phosphate group of DNA resulting in enhanced electron transport. The ssDNA/NanoZrO2 bioelectrode shows a detection range from 1 � 10 � 8 to 10 nM of complementary DNA of V. cholerae within 60 s of hybridization time at 258C using methylene blue as an electroactive indicator. This O1 gene based metal oxide (ZrO2) sensor exhibits sensitivity for ssDNA/NanoZrO2/ITO bioelectrode as 0.48 mA/nM cm � 2