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Indium tin oxide powders containing different amount of tin were prepared using a facile water based sol-gel procedure. The structural and microstructural properties have been analysed with X-ray diffractometer, FTIR-spectroscopy, XPS, TEM and EDX analysis. The nanocrystalline powders were used to fabricate Taguchi design based thick film sensors and their low concentration ammonia sensing (30 ppm) performance were evaluated in the operating temperature range of 200–400 °C. Indium tin oxide sensor having 20 wt% tin oxide showed the optimum response, ∼61% for 30 ppm ammonia at operating temperature of 300 °C. Pd incorporation led to a significant enhancement in sensing response (∼82%) at the same condition. A good sensing response (∼43%) was also observed even at very low ∼ 3 ppm of ammonia concentration. The interference of other gases was almost insignificant. The sensor was stable as reflected from the observation of negligible decrease in the sensing performance of sample up to 90 days period. The sensing mechanism for enhancement has also been explained.

An inorganic-organic hybrid of SnO2-reduced graphene oxide (rGO)-polyaniline (SGP) nanocomposite has been successfully synthesized from surfactant-free precursor by a low temperature solution process. The SGP nanocomposite is found to form from in situ synthesized SnO2-rGO (SG) and polyaniline (PANI), generated via polymerization of aniline monomer at 5–10 °C. The structural properties of SGP have been analyzed by X-ray diffraction, transmission electron and atomic force microscopes. The chemical interaction existed in the nanocomposite has been examined by X-ray photoelectron, Fourier transform infrared and Raman spectroscopies. Compare to pristine SnO2 and SG, the SGP sample shows an enhanced ammonia gas sensing at room temperature. At an optimum content of PANI, high sensitivity, fast response and good selectivity of the gas sensing are observed in the nanocomposite. This enhanced sensing performance can be attributed to well-defined p-n hetero junction formation in the hybridized polyaniline and rGO with nano SnO2 in SGP as confirmed from structural characterization of the sample. It is also seen that the presence of PANI layers in SGP, enhances the chemical stability as reflected from the observation of negligible decrease in the sensing performance of sample up to 30 days period. This facile process can create an avenue for development of various metal oxide semiconductor-graphene-polyaniline nanocomposites for improving room temperature stable ammonia gas sensor.

1 wt% Pd impregnated gallia: tin oxide nanocomposite sensors were investigated for high temperature carbon monoxide detection. Initially the mixed oxide nanopowder, containing 25 wt% gallia, was synthesised using a facile cost effective sol-gel procedure. 0.25 wt% antimony doping was done to facilitate lower resistance of the corresponding sensor in terms of electronic perspective. The structural and microstructural characterizations of the nanocomposites were carried out with X-ray diffractometer, BET surface area, XPS, TEM and EDX analyses. Taguchi design based thick film sensors were fabricated and CO sensing performance was evaluated in the operating temperature range of 300–500 °C. Nanocomposite sensor showed ∼ 48% optimum response for 30 ppm CO at temperature of 425 °C with stable low resistance. Pd incorporation led to a significant improvement in sensing response (∼65%) at the same condition along with decrease in response and recovery times. Possible sensing mechanism of enhancement has been explored.

A ternary p-n-n heterojunction has been prepared by introducing reduced graphene oxide (rGO) in ZnO-SnO2 nanocomposite and its ppm level volatile organic compounds (VOCs) sensing properties have been exploited. Using a simple, facile sol-gel process, initially, ZnO-SnO2 nanocomposites containing different concentrations of ZnO and SnO2 were prepared and subsequently this was followed by rGO incorporation. The as-synthesized powders were well characterized through XRD, FTIR, Raman spectroscopy, FESEM, TEM, and XPS analyses. The sensing study revealed that, the ternary nanocomposite sensor delineated ~91% n-type sensing response towards ~10 ppm acetone gas at an optimum working temperature of 150 °C. Even it could sense ~1 ppm acetone with appreciable sensing response of ~71%. Additionally, the sensor displayed fast response (~10 s) and recovery time (~100 s) suitable for detection of multiple pulses in short time duration. It also exhibited a considerable ~65% sensing response towards ~10 ppm ethanol at 150 °C. These superior sensing performances of rGO decorated ZnO-SnO2 nanocomposite illustrated with band structure modification. Our results indicated that, the fabricated rGO decorated ZnO-SnO2 sensor, with remarkable high sensing response, minimum interference from other toxic, inflammable gases and profound long term stability, could be considered as a prolific candidate for real time detection of low concentration VOCs in versatile commercial applications.

Trimanganese tetraoxide (Mn3O4)-silver (Ag) nanocomposites have been synthesized by seed-mediated growth of manganese oxide by alkaline hydrolysis of manganese precursor on preformed silver nanoparticles at water/n-heptane interface. The morphology of the nanocomposites has been varied by individual addition of five size-selective silver nanoparticles for the evolution of the manganese components. Varieties of spectroscopic and microscopic techniques have been used to characterize these materials. Now, the efficacy of these as-synthesized nanocomposites has been demonstrated towards the sensing of various hazardous volatile organic compounds, exhibiting high sensitivity to ethanol compared to other components. Moreover, the structure-function relationship of the Mn3O4-Ag nanocomposites upon variation of the size of silver particles towards the sensory activity of ethanol has been elucidated.

Self-supported polyethylene and deuterated polyethylene targets of thickness in the range of 0.3 mg/cm2 to 2.5 mg/cm2 were prepared using the solvent casting technique. A quantitative estimation of material required for the solvent casting technique has been presented. Overall target preparation time has been reduced from the earlier reported methods. Comparative studies between polyethylene of the two different isotopes (hydrogen/deuterium) were performed in terms of their different characteristic properties e.g. target thickness, uniformity in the target thickness, infrared transmission and melting temperature. The effect of deuteration is clearly seen in the infrared transmission and melting point of the polyethylene, which may have potential applications in other fields of research. Target prepared in this work has been used for an in-beam experiment, where yield of the deuteron produced is found to be sensitive to the hydrogen isotope present in the polyethylene target.

In the present report, an enhanced sub-ppm level acetone sensing performance of a novel Pt and Sb2O3 impregnated nanocrystalline Fe2O3 thin film operating at room temperature has been explored. Starting from organic precursor sols, thin films of thickness ~ 6 µm were drop-casted on planar alumina substrates pre-attached with the platinum electrodes and cured at ~ 350°C. The characterizations of the materials have been carried out using X-ray Diffraction, FTIR, Raman Spectroscopy, micro structural study through FESEM and TEM as well as XPS analyses. The sensing characteristics including sensing response, lowest detection limit, recovery time etc. of these chemiresistive thin films were studied on exposing them to various concentrations (0.25 to 1 ppm) of acetone at room temperature. The sensing response of ~2.4 with ~ 95 s recovery time was observed on exposure to 1 ppm acetone for 10 s. Even at 0.25 ppm acetone, the response observed ~ 1.4. Selectivity study on different alcohols and other interfering gases of breath has also been tested. Additionally, a real time breath acetone measurement was carried out and acetone sensing mechanism has been elucidated.

Cd–Sn oxide nanocomposite powders were synthesized by a facile gel calcination method, starting from precursor sol having Cd:Sn ratio as 2:1. The powders were characterized in terms of their phase formation behaviour and morphological features using X-ray diffractometer, FTIR, UV–visible spectra and FESEM analyses. Sensor fabricated from nanocomposite calcined at 1050 °C exhibited excellent ethanol sensing performance, ~86 % for 50 ppm ethanol vapour. It also revealed quite a good sensitivity at concentration down to 5 ppm vapour. Sensors were quite stable and selective towards ethanol vapour. A possible mechanism for enhanced performance due to formation of preferential perovskite cadmium stannite phase has been discussed.

This study reports on a simple unconventional procedure for synthesis of γ-Fe2O3 nanopowder and its fabrication as a resistive ethanol sensor. γ-Fe2O3 powder having an average particle size of ∼15 nm was prepared by thermal decomposition of iron(III) acetylacetonate. Platinum incorporation (0.5–1.5 wt.%) was also carried out for enhancing sensing performance. The powders were characterized using an x-ray diffractometer, x-ray photoelectron spectroscopy, Brunauer–Emmett–Teller surface area, field area scanning electron microscopy, transmission electron microscopy along with energy dispersion x-ray analyses. Sensor fabricated from pure γ-Fe2O3 exhibited excellent ethanol sensing performance at concentrations down to 1 ppm, having a great demand in medical diagnosis and food-processing industries. The response observed for pure γ-Fe2O3 (∼75% for 1 ppm ethanol) was enhanced ∼10% after 1 wt.% Pt impregnation. Sensors were quite stable and selective towards ethanol vapour detection. A possible mechanism for high sensing performance has been discussed.

Cd-Sn oxide nanocomposites were synthesized by sol-gel method from precursor sol containing Cd:Sn = 2:1 and 1:1 mol ratio. Instead of coprecipitation, a simple novel gel calcination route was followed. Cd (NO3)2. 4H2O and SnCl4. 5H2O were used as starting materials. Gel was calcined at 1050 °C for 2 h to obtain nanocomposites. XRD analysis reveals the presence of orthorhombic, cubic Cd2SnO4 along with orthorhombic, hexagonal CdSnO3 phases in both the composites. SEM and TEM studies indicate the development of nanocomposites of different shapes suggesting different degrees of polymerization in precursor sol of different composition. UV-Vis absorption spectra show a blue shift for both the composites compared to bulk values. Decrease of polarization with frequency, dipole contribution to the polarization, and more sensitivity to ethanol vapor were observed for the nanocomposite derived from precursor sol containing Cd:Sn = 2:1 mol ratio.

Metal oxide nanocomposite sensors based on γ-Fe 2 O 3 and WO 3 were investigated in acetone vapor of various concentrations (1–100 ppm) at operating temperatures between 250 and 350 °C. The composites were prepared by simple solid state mixing and porous thick-film gas sensors were fabricated on alumina substrates. The γ-Fe 2 O 3 :WO 3 (50:50) nanocomposite showed a marked enhancement in sensing response down to 1 ppm acetone vapor detection at 300 °C. The response was ~2-fold better compared to pure WO 3 or pure γ-Fe 2 O 3 with a very fast response (1 s) and very short recovery time (3 s). No appreciable sensitivity was observed towards alcohol vapor (an interfacing agent for diabetics) and in moisture (present in breath). The enhanced performance was due to n–n heterojunction effect.

The present work reports on a novel resistive ppm level ethanol sensor, prepared from nanocrystalline lanthanum loaded indium tin oxide (ITO) impregnated with palladium and antimony additives. A simple unique gel calcination process was adapted to synthesize the nanocomposite powders from their water based precursor salts. This was followed by detailed material characterizations through X-ray diffractometer, FESEM, TEM, EDX and XPS analyses. Fabricated Taguchi type sensor with an optimum concentration of Pd exhibited an excellent sensing performance towards a wide concentration range of (1–100 ppm) ethanol vapour. The sensor showed ~87% sensing response for 10 ppm ethanol vapour at an operating temperature of 300 °C. Even at 1 ppm concentration, ~53% response was observed with fast response and recovery time. The sensing action has been elucidated as the catalytic oxidation of ethanol to carbon di oxide over the La loaded ITO surface layer that resulted in electron transfer to the indium tin oxide site. In addition, synergistic effect of palladium and antimony enhanced the sensing performance as well as reduced the base resistance of the sensor by chemical/electronic sensitization and increasing carrier ion concentration respectively. Comparatively low resistance, negligible cross sensitivity, quick response/recovery time and good long term stability makes the sensor suitable for deployment in practical applications.

4 wt% La-doped SnO2 nanocrystalline powders impregnated with 0.5–1.5 wt% Pd were synthesized by a facile sol–gel method. The powders characterized through XRD, TEM, EDX as well as XPS analyses were used for the fabrication of sensors. 0.5 wt% Sb2O3 was incorporated in each case to reduce the resistance of sensors. The gas response studies revealed a large enhancement in low concentration (1–100 ppm) ethanol vapour sensing at comparatively lower operating temperature (300 °C) on 1.0 wt% Pd incorporation. The response observed (~86 %) for 10 ppm vapour was ~16 % greater compared to 4 wt% La-doped SnO2 with improved response (2 s) and recovery (15 s) times. The high ethanol vapor response at comparatively lower operating temperature of this sensor is attributed to the combinatorial effect of alkalescence of SnO2 due to La-doping and widening of depleted region by spill-over process of PdO present on SnO2 surface.

Nanocrystalline undoped and lanthanum(III) doped (2, 4 and 6 at%) tin oxide powders were synthesized using sol–gel processing from their water based precursor sols. Microstructures and surface morphologies of all powders were characterized using X-ray diffractometer, BET surface area, UV–Visible spectrophotometer, scanning and transmission electron microscope along with energy dispersive X-ray diffractometer. XRD and UV–Vis spectral analyses revealed decrease of tin oxide crystallite size on La(III) doping. 4 at% La(III) doped powder showed ~5 nm average particle size and ~42 m2/g surface area respectively. A systematic comparison study revealed that sensors made from 4 at% La(III) doped SnO2 powder exhibited optimum ethanol vapor sensing performance at operating temperature, 350 °C (response ~70 % for 10 ppm ethanol) with excellent response and recovery times. Even for very low concentration ethanol vapour (1 ppm) response observed was ~53 %. A possible mechanism for enhancing sensitivity on La(III) doping has been discussed.

The controlled synthesis of a hierarchically assembled porous rectangular ZnO plate (2.5–3.5 μm length, 1.5–2.5 μm width and 100–150 nm thickness) from bulk ZnO without using any organic substrates, such as solvents/surfactants/structure-directing agents, is presented. The synthesized ZnO plates are single crystalline with exposed (100) facets on the flat surface, porous and formed through the calcination of a hydrozincite [Zn5(CO3)2(OH)6] intermediate. A gas sensor based on the synthesized porous ZnO architecture exhibited high sensitivity towards acetone even in low concentration (S = 3.4 in 1 ppm acetone) with good selectivity. The ZnO nanostructured material as a heterogeneous catalyst also showed excellent catalytic activity for the synthesis of 5-substituted-1H-tetrazoles (yield = 94%). Both the activities are superior than those of other reported ZnO based acetone sensors and heterogeneous catalysts. We believe that the improved properties of the synthesized ZnO nanostructure is due to the exposed (100) facets, and its porous and assembled structure, which provides a reasonably large accessible surface area, and facilitates diffusion and mass transport of gas or substrate molecules.

The present paper reports on a unique eco-friendly bio-synthesis process of tin oxide using water extract of soaked kabuli chickpea seeds as natural binder. The structural, microstructural and CO sensing properties of the newly synthesized tin oxide were compared with those of conventional sol–gel and sonochemical processes. XRD results of the bio-synthesized material revealed the formation of single tetragonal phase of SnO2 similar to sol–gel and sonochemical processes. The bio approach led to the formation of finer nanoparticales with a higher specific surface area ∼ 60 m2 /gm compared to the others. The average sizes of tin oxide nanoparticles as observed from TEM images were about 35 nm, 15 and 6 nm for the sonochemical, sol-gel and biosynthesis respectively. These tin oxide powders were used to fabricate Taguchi based sensors and their CO sensing performance were evaluated. The biosynthesized tin oxide sensor showed ∼53% sensing performance for 30 ppm CO which was better than sol-gel (∼44%) or sonochemical (∼42%) tin oxides operating at similar condition. The reported results suggest that the biosynthesis is a promising cost effective method to prepare nanocrystalline SnO2 for sensing application.

We observe remarkably strong room temperature ferromagnetism (~1.5 Bohr Magneton/Mn) in optically transparent Mn(II)-doped indium tin oxide (ITO) films. The nanocrystalline films with average grain size 10-22 nm and thickness 150-350 nm are prepared by sol-gel coating technique on sodalime silica glass substrate. The ferromagnetic property is, of course, weak for films deposited on pure silica glass substrate. The structural parameters of the films appear to be governing the magnetic property strongly which vary appreciably depending on the substrate. The observation of room temperature ferromagnetism in transparent conducting ITO films may find a plethora of applications in the area of magneto-optics., Comment: 17 pages including 3 figures; pdf only

The physicochemical compositions of 20 black-seeded soybean lines were analyzed for different nutritional and cooking quality parameters. The range of variation for different characteristics was 1.04–1.20 g/mL for density, 17.34–30.20 kg for hardness, 72.7–214.4 µg/seed for hydration capacity, 1.06–1.24 for hydration index, 75.6–203.4 µL/seed for swelling capacity, 0.99–1.58 swelling index, 32.1–39.8% for protein, 10.8–19.6% for oil, 3.93–6.15% for total minerals, 131–205 mg/100 g for phosphorus, 6.4–13.9 mg/100 g for iron, 0.49–0.89 mg/g for trypsin inhibitor, 2.1–6.4 mg/g for phytic acid and 60.4–13.4 µg/g for polyphenols. Based on 18 physicochemical and nutritional attributes, 20 black soybean germplasm lines were grouped into four clusters using nonhierarchical Euclidean cluster analysis. The DARL-BK-615 and VRB-PS-1453 were found to be more diverse than others. The DARL-BK-615 was found best for low trypsin inhibitor and high mineral contents (Zn, Mn, Cu), while VRB-PS-1453 was found best for protein content and required the lowest time for cooking. The selection for the improvement of physicochemical nutritional attributes and antinutritional factors can be independently effective in black soybean genotypes. PRACTICAL APPLICATIONS This study has shown that sufficient variability for cooking quality, protein, oil, micronutrients and antinutritional factors exist in black soybean germplasm lines of the Himalayan region of India, which can be independently improved by the breeders. Different genotypes in four diverse groups may be used to develop improved lines with better nutritional and cooking quality coupled with low antinutritional factors for consumption as pulses. Germplasm lines with high protein, low levels of antinutrients and superior nutritional and cooking quality are useful materials for the improvement of quality in high-yielding soybean lines.

Evaluation of suitable organic amendments is prerequisite for sustainable agricultural growth in the northwestern Himalayan ecosystem. The effect of organic amendment applications on the activity of exocellular enzymes were examined on a silty clay loam soil of a subtemperate hill-agro ecosystem. The treatments involved addition of equivalent amounts of N through mineral fertilizer (MF) and two organic inputs, composted cattle manure (CM) and vermicomposts (VC), at four different doses. Soil enzymatic activities and fertility at crop harvest were measured after continuous 3 years of application, and its residual effects were also studied. In comparison with the control, CM and VC addition increased soil organic carbon (OC) by 54% and 52% at application rate equivalent to recommended dose, respectively, whereas there was a 12% increase following MF treatment. Bulk density of CM- and VC-treated soil were 1.16 and 1.14 Mg m−3, respectively, compared with 1.32 Mg m−3 in control after 3 years. Dehydrogenase activity was higher in the CM treatments by 44–204%, and by 22–108% in VC treatments than in control. The addition of CM and VC caused different responses in hydrolase enzymes. Protease and cellulase activity increased in both organic treatments significantly across treatments. However, urease and alkaline phosphatase activity was more influenced by application of CM compared with VC. β-glucosidase activity was higher in MF treatment and was at par with the highest rate of organic amendment application. Increase in phosphatase activity is attributed to soil pH and microbial stimulation by organic C and is correlated with the increase in dehydrogenase activity (R 2 = 0.923). Differences in activities of all evaluated enzymes were narrowed down in residual treatments compared with control without much change in the trend. Composted CM was found more suitable for sustaining quality of subtemperate soils.

The use of organic nutrient sources in improving crop quality can be a viable alternative to traditional farming. Organic farming encourages the reduction of agrochemicals and promotes soil conservation principles. Although crop quality depends on several factors, among which the nutrient source plays a great role, there is little information available on how rice quality is affected by different organic composts. Here we grew aromatic rice on two levels of four organic composts made from kudzu vine (Pueraria lobata) at 5 and 10 Mg ha−1, Urtica sp. (nettle) at 5 and 10 Mg ha−1, Lantana sp. at 5 and 10 Mg ha−1, winter weeds at 2.5 and 5 Mg ha−1, and two other organic amendments of poultry at 2.5 and 5 Mg ha−1 and farmyard manure at 5 and 10 Mg ha−1. We studied the effect of these organic sources on nutritional and physico-chemical properties, and on the cooking quality of the rice, using a fertilized, chemical treatment as positive control. Our results show that grain yield was significantly influenced by the supply of major plant nutrients. The highest rice yield of 4.0 Mg ha−1 was obtained from the inorganically fertilized treatment. The protein content in grains was the highest, 8.98%, in the inorganic treatment (100:60:40 kg N, P, K ha−1) and lowest, 7.55%, in the control. Among organic treatments, farmyard manure at 10 Mg ha−1 contributed the least in terms of the protein content of the rice (7.78%). Significantly higher iron content, of 52.2 μg g−1, was recorded with organic fertilization than inorganic fertilization (42.1 μg Fe g−1). However, inorganic fertilization was superior in terms of copper content, of 4.1 μg Fe g−1, compared with organic treatments: 3.1–4.0 μg Fe g−1. Quality attributes indicated that cooked kernel length was positively correlated with the kernel elongation ratio. Winter weed compost provided comparative benefits for rice yield (3.87 Mg ha−1) and quality in terms of protein (8.42%), iron (48.31 μg g−1) and head rice recovery (49.39%) compared with other sources of nutrients. The results of this study suggest that organic nutrient sources can perform comparatively well as regards chemical and physico-chemical properties, and cooking quality of rice, if not better in some parameters than inorganic fertilization.