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The title Schiff base compounds, C22H26N4O (I) and C18H16FN3O (II), were each synthesized by a single-step condensation reaction. The substituted benzylidene ring is inclined to the pyrazole ring mean planes by 22.92 (7)° in I and 12.70 (9)° in II. The phenyl ring of the 4-aminoantipyrine unit is inclined to the pyrazole ring mean plane by 54.87 (7)° in I and by 60.44 (8)° in II. In the crystal of I, the molecules are linked by C—H...O hydrogen bonds and C—H...π interactions to form layers lying parallel to (001). In the crystal of II, the molecules are linked by C—H...O and C—H...F hydrogen bonds and C—H...π interactions, thereby forming layers lying parallel to (010). Hirshfeld surface analysis was employed to further quantify the interatomic interactions in the crystals of both compounds.

The crystal structure of the title compound, C13H9Br2N [systematic name: (E)-N,1-bis(4-bromophenyl)methanimine], is a second polymorph (Form II) crystallizing in the orthorhombic space group Pccn. The first polymorph (Form I) crystallizes in the monoclinic space group P21/c [Bernstein & Izak (1975). J. Cryst. Mol. Struct. 5, 257–266; Marin et al. (2013). J. Mol. Struct. 1049, 377–385]. The molecule is disordered about an inversion center situated in the middle of the C=N bond, similar to the situation in the monoclinic polymorph: the C=N bond length is 1.243 (7) Å. In the crystal, molecules stack along the b-axis direction and are linked by C—H...π interactions. The interatomic contacts in the crystal for both polymorphs were studied by Hirshfeld surface analysis and have notable differences. The solid-state fluorescence spectrum of Form II shows an emission peak at ca 469 nm. The two-photon absorption coefficient measured from the open aperture Z-scan technique is 1.3 × 10 −11 m W−1, hence, Form II shows optical limiting behaviour.

The title polymeric compound, (C7H10N)4[Cd3Cl10], involves a centrosymmetric [Cd3Cl10]4− tetra-anion, which is made up of three face-sharing CdCl6 octahedra, linked by four corner Cl atoms, forming layers propagating in the ab plane. The p-methylanilinium cations, situated between the layers, form N—H...Cl hydrogen bonds to the layers, which stack up the c-axis direction. There are no π–π or C—H...π interactions involving the aromatic rings, which are inclined to each other by 42.3 (1) ° in the asymmetric unit.

CdTe and 1–5 wt% molybdenum-doped CdTe materials were prepared by ball milling method. Then the ball-milled samples were deposited on a glass substrate at room temperature by an electron beam evaporation method. The structural, optical, morphological, electrical, and photo-response properties of CdTe and Mo-doped CdTe (CdTe:Mo) samples were investigated. The prepared samples exhibit a cubic structure of CdTe. X-ray diffraction pattern (XRD) showed that the deposited films belong to the cubic structure with a preferential growth along (111) plane. The peak shift in the lower side of 2θ was observed due to incorporation of Mo into the CdTe matrix. Surface morphology of the prepared CdTe and CdTe:Mo ball-milled samples showed the formation of various agglomerated structures. Scanning electron microscope images depicted the formation of high dense agglomerated grains on the film surface with varying sizes as a function of Mo concentration. The optical bandgap was increased from 1.38 to 1.54 eV with raising the Mo concentration in CdTe films. Enhanced optical absorption coefficients (~ 17 × 104 cm−1) were observed for 3 and 4 wt% Mo doped CdTe thin films. Hall measurement studies revealed that Mo doped CdTe (3 wt%) film possesses a low resistivity of 34 × 103 Ω cm. The CdTe and CdTe:Mo films exhibit p-type conduction. The high photo-response of 0.088 AW−1 is observed for 3 wt% Mo-doped CdTe thin film.

Template/surfactant-free ZnO nanoparticles were synthesized by hydrothermal process at 120 °C, 150 °C, 180 °C and 210 °C for 3-h duration and were annealed at 400 °C for 3 h. Since the ZnO nanoparticles synthesized at 150 °C for 3 h and annealed at 400 °C for 3 h showed improved photocatalytic activities, the ZnO nanoparticles were further synthesized at 150 °C for 6-h, 9-h, and 12-h durations and were annealed at 400 °C for 3 h. All the synthesized ZnO nanoparticles were characterized for their structural, optical, and morphological properties. X-ray diffraction analysis confirmed that the ZnO nanoparticles belong to the hexagonal wurtzite system. Transmission electron microscopy and high-resolution transmission electron microscopy analyses revealed that the hydrothermally synthesized ZnO nanoparticles at 150 °C for 3 h and annealed at 400 °C for 3 h acquired spherical and hexagonal morphologies with size ~ 50 nm. Variation in the hydrothermal temperatures and time durations with annealing at 400 °C for 3 h acquired nearly hexagonal, spheroidal, and hexagonal morphology of the ZnO nanoparticles. Optical band gap of synthesized ZnO nanoparticles was slightly influenced by the different synthesis parameters. The photocurrent measurements revealed that the ZnO nanoparticles synthesized at 150 °C for 3 h and annealed at 400 °C for 3 h possess relatively enhanced of photocurrent of about 3.58 μA than that of the other synthesized samples. The ZnO nanoparticles synthesized at 150 °C for 3 h and annealed at 400 °C for 3 h showed ~ 78% and 36% of photodegradation efficiency against Rhodamine B dye and 4-chlorophenol, respectively, in a time period of 60 min. The sonophotocatalytic activity process enhanced degradation efficiency to 99% in 60 min against Rhodamine B and 80% in 60 min against 4-chlorophenol.

Metal oxide frame works along with carbon materials have been attracting tremendous attention of researches as the potential materials for energy and environmental remediation. In the present work heterostructures of (ZnO/CuO)/rGO ternary nanocomposites were synthesized by solid-state method. The crystalline structure of the nanoparticles was obtained from the XRD analysis. Optical band gap of the ZnO nanoparticles (3.1 eV) is tuned to 2.8 eV in the synthesized (ZnO/CuO)/rGO ternary nanocomposites. Field emission scanning electron microscope images of the (ZnO/CuO)/rGO ternary nanocomposites revealed formation of well-developed flowers like morphology of (ZnO/CuO) nanoparticles on rGO sheets. Photoluminescence spectroscopy analysis of (ZnO/CuO)/rGO ternary nanocomposites show enhancement in the electron-hole pair separation and thereby diminishing electron-hole pairs recombination rates effectively. In the present work, the photocatalytic activity of the ZC3G15 ternary nanocomposites show 99% and 93% of degradation efficiency respectively against RhB dye and 4-chlorophenol for 20 min under visible light irradiation. Thus, the simple solid-state method provides the effective ternary nanocomposites heterostructures light harvesting material for energy and environmental remediation. Keywords: Powders: solid state reaction, Nanocomposites, X-ray methods, Optical properties, Reduced graphene oxide, Photocatalytic activity

ZnO nanoparticles, known as one of the potential materials for photocatalytic application, were synthesized by template/surfactant-free hydrothermal method and annealed at different temperatures. Annealing the ZnO at 400 °C modified the rod-like structures into irregular shaped structures. Further, using wet impregnation method ZnO/reduced graphene oxide (rGO) nanocomposites were prepared for various amounts of rGO. Field emission scanning electron microscopy (FESEM) analysis revealed that ZnO/rGO (6 mg) nanocomposites contain both ZnO and rGO nanoparticles. Optical band gap of the as-synthesized ZnO nanoparticles was slightly shifted from 3.09 to 3.02 eV in ZnO/rGO (6 mg) nanocomposites. Photoluminescence spectral analysis showed that the electron–hole pair recombination rate is effectively suppressed in the ZnO/rGO (6 mg) nanocomposites. Further, the photocurrent measurements revealed that ZnO (annealed at 400 °C) acquires a photocurrent of 2.8 μA/cm2 and is increased to 4.8 μA/cm2 for ZnO/rGO (6 mg) nanocomposites. UV light irradiation exhibited that ZnO nanoparticles annealed at 400 °C show 94% degradation efficiency against Rhodamine B dye for 120 min. Further, ZnO/rGO (6 mg) nanocomposites acquired degradation efficiency of 94% against Rhodamine B dye for 20 min with a better cycling stability up to five cycles.

The present work reports on a novel ternary nanocomposite of ZnO rods encapsulated by graphitic like carbon nitride (g-C3N4) and coupled with graphene oxide (GO) prepared by ultrasonication assisted hydrothermal method which provides enhanced photocatalytic activity and stability. Field emission scanning electron microscopy analysis showed that the surface morphology of ZnO, g-C3N4 (prepared by heating method) and the GO contains nanorods structures, sheet like structures and sheets with porous structures respectively. Formation of rod like structures of ZnO and thin sheet like structures of g-C3N4 were observed from transmission electron microscopy analysis. Transmission electron microscopy analysis of g-C3N4 (6 wt%)/ZnO nanocomposites showed that ZnO nanorods are encapsulated by the thin sheets of g-C3N4 and g-C3N4(6 wt%)/ZnO/GO (30 mg) ternary nanocomposites contains porous structures of GO. The optical band gap of ZnO nanoparticles was shifted from 3.08 eV to 2.85 eV for g-C3N4(6 wt%)/ZnO/GO(30 mg) ternary nanocomposites. Under visible light irradiation the ZnO nanorods and g-C3N4 (6 wt%)/ZnO showed photodegradation efficiency of ∼21% and 90% respectively for 120 min whereas g-C3N4 (6 wt%)/ZnO/GO(30 mg) showed about 99% photodegradation efficiency in a time period of 14 min. The recycle process carried out for g-C3N4(6 wt%)/ZnO/GO(30 mg) composites up to five cycles showed 91.5% of photodegradation in the fifth cycle for a time period of 14 min. Total Organic Carbon (TOC) analysis shows removal of carbon content 83% in 28 min. The Gas Chromatography-Mass Spectroscopy analysis shows the intermediate products of 1,2 benzenedicarboxylic acid and phthalic acid during the RhB dye photodegradation process. The radical trapping experiment reveals that the photo-induced holes (h+) are one of the main reactive species involved in the degradation of the RhB. Keywords: g-C3N4/ZnO/GO ternary nanocomposite, Ultrasonication, Hydrothermal, Optical band gap, Raman analysis, Photocatalysts

Shape-controlled synthesis of AgBiS2 nano-/microstructures by a facile solution-based route is reported. One-dimensional AgBiS2 nano-/microspheres were synthesized through solvothermal method using ethylene glycol as the solvent and polyethylene glycol (PEG) as a soft template. The growth mechanisms related to the morphology control and phase formation of AgBiS2 were discussed. X-ray diffraction results confirmed that the cubic structure of AgBiS2 was formed for 0.04 mol of thiourea in the precursor solution. Raman spectrum of the AgBiS2 revealed the presence of the functional groups. X-ray photoelectron spectroscopy exhibited Ag 3d, Bi 4f and S 2s core levels for AgBiS2, thus confirming the pure and secondary phase of the samples. Field-emission scanning electron microscope and transmission electron microscope analyses exhibited the systematic transformation of agglomerated nanorods into microsphere, due to increase in the thiourea concentration. The vital role played by the thiourea concentration in modifying the morphology of AgBiS2, is discussed. Elemental mapping analysis confirmed the uniform distribution of the elements. The direct optical band gap of AgBiS2 nano-/microstructures vary from 0.98 to 1.01 eV. Synthesized samples were used to deposit thin films on FTO substrate using spray pyrolysis method. The I-V characteristics of the films exhibited ohmic nature and showed high conductivity for the nanorods sample.

We report on the effect of α-Fe₂O₃ phase in the magnetic properties and magnetic interactions in nickel ferrite (NiFe₂O₄-NFO) nanoparticles synthesized by co-precipitation method. Structural analysis confirms the formation of the cubic inverse spinel phase without any impurities for the NFO sample annealed in air at 650 °C. When the annealing temperature is increased to 750 °C and 850 °C, α-Fe₂O₃ impurity phase is formed along with the parent NFO phase. Raman spectra recorded at room temperature (RT) confirm the presence of pure NFO phase for the sample annealed at 650 °C, and presence of α-Fe₂O₃ phase is observed in the samples annealed at 750 °C and 850 °C. Saturation magnetization values at RT for the NFO samples annealed at 650 °C, 750 °C and 850 °C are 34 emu/g, 19 emu/g and 28 emu/g respectively. Zero Field Cooled (ZFC) and Field Cooled (FC) measurement reveals the super-paramagnetic behavior along with competing magnetic interactions in all the samples. For the NFO sample annealed at 750 °C and 850 °C, a drop in ZFC magnetization and a small kink in FC magnetization observed around 245 K indicate the presence of a Morin transition (TM) from the α-Fe₂O₃ phase. Anisotropy constants were calculated for all the samples using the law of approach to saturation (LAS) method. The magnetocrystalline anisotropy energy distribution function for the NFO samples annealed at 750 °C and 850 °C exhibit broad peak due to the random distribution of spins associated with different particle size.

A new material, Ti doped CdO (Ti: CdO) semiconductor, is firstly reported by this work for electrochemical non-enzymatic hydrogen peroxide (H2O2) sensor applications which was deposited by a simple, versatile and cost-effective chemical spray pyrolysis method on indium doped tin oxide (ITO) substrate. In the basic studies, first, the withstanding of cubic crystal phase along with worthy crystalline nature is discerned on CdO film after Ti doping, here only the preferentially orientated (200) diffraction plane shifted to (111). Subsequently, the irregular spherically shaped CdO nanoparticles (NPs) morphology changed as nearly uniform size with Ti doping is noticed under thermal pyrolytic decomposition process. The existence of Ti atoms in Ti: CdO film is authentically identified and confirmed using EDX and XPS studies respectively. The absorption and emission properties of CdO and Ti: CdO films are studied and confirmed their narrow band gap nature. Importantly, the Ti: CdO film shows pronounced electrocatalytic activity for the reduction of hydrogen peroxide (H2O2) than pure CdO. Hence, the non-enzymatic electrochemical sensing of Ti: CdO electrode shows a lower detection limit, broad linear range, rapid response time and high sensitivity toward H2O2 detection. This result will boost exploring a new opportunity for the deposition of other metal oxides and semiconductors by using a simple chemical spray pyrolysis method for detection of non-enzymatic H2O2 sensor applications.

We report on magnetocapacitance, spin dynamics through AC succeptability measurements and dielectric anomalies in 0.3NiFe2O4 – 0.7BiFeO3 nanocomposite. Structural studies (purity and phase) and surface morphology of the 0.3NiFe2O4 – 0.7BiFeO3 nanocomposite were examined by X-ray diffraction (XRD), Raman Spectra, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). TEM and SEM images indicate the uniform distribution of nanoparticles in parent pahase as well as in the composite. Energy dispersive X-ray (EDX) analysis indicates the presence of Ni, Fe, O and Bi elements in 0.3NiFe2O4 – 0.7BiFeO3 nanocomposite. Magnetization measurements were performed at 300 K, 50 K and at 2 K and the Field Cooled (FC) and Zero Field Cooled (ZFC) measurements were carried out from 350 K to 2 K. ZFC and FC magnetization curves exhibit a hump around 30 K indicating the existence of competing magnetic interactions and possible spin galss behaviour. AC succeptibility measurements at various frequencies confirm the spin glass freezing behaviour of 0.3NiFe2O4 – 0.7BiFeO3 nanocomposite around 25 K with the relaxation time and activation energy in the order of 10−7 s and 0.938 meV respectively. The dielectric constant and dielectric loss at various frequencies and temperatures indicate the dielectric relaxation behaviour of 0.3NiFe2O4 – 0.7BiFeO3 nanocomposite. A rapid increase in the dielectric constant near the antiferromagnetic transition temperature (TN ∼ 643 K) of BiFeO3 indicates the existence of magneto-electric coupling in this composite. Magnetocapacitance (MC) of 0.3NiFe2O4 – 0.7BiFeO3 composite was measured at room temperature and the MC values of 13.5% and 7.8% (at 5000 Oe) are observed when the pellet is perpendicular and parallel to the magneticfield direction respectively. The presented magnetic and dielectric studies reveal the existence of magnetoelectric coupling and spin glass frezing of 0.3NiFe2O4 – 0.7BiFeO3 nanocomposite.

The growth of one-dimensional (1D) zinc oxide (ZnO) nano/micro rod arrays (N/MRAs) thin films by using a facile, reproducible and cost effective method could be triggering nano/micro morphological structure based devices in the semiconductor technology. Therefore, in this work, the chemical bath deposition (CBD) and hydrothermal (HTM) methods have been used for growing 1D ZnO N/MRAs thin films on ZnO seeded glass substrates. Subsequently, we have studied their fundamental physicochemical properties for determining and distinguishing the growth characteristic of deposition methods. The formation of hexagonal wurtzite crystal structure in the CBD and HTM grown 1D ZnO N/MRAs films has been confirmed by XRD and μ-Raman studies. The intensity of the preferentially oriented diffraction peaks and electron microscopic images depict that the crystallinity , number density and aspect ratio of the 1D ZnO N/MRAs are strongly dependent on level of degree of supersaturation and its changes under deposition method is highlighted here. Further, the size, shape and single crystalline nature of the N/MRAs are strongly confirmed by TEM images and SAED patterns respectively. The photons absorption in the UV region ratify the wide bandgap characteristic of ZnO. Eventually, the presence of localized electron trapping and/or relaxing states in ZnO nuclei layer and in 1D ZnO N/MRAs films are determined from photoluminescence spectra.

In the title salt, {[Li(C2H5NO2)2]ClO4} n , the Li+ cation is coordinated by four carboxylate oxygen atoms of the glycine molecules with a distorted tetrahedral geometry. The glycine exists in a zwitterionic form with protonated amino and deprotonated carboxylate groups. In the crystalline state, the title salt is primarily stabilized by intermolecular N—H...O and Cα—H...O interactions which interconnect various units. Hirshfeld surface analysis indicates that the intermolecular H...O/O...H interactions are the most important contributors to the crystal packing.

Explosions involving gaseous fuels, vapors, dust, and condensed phase materials have been discussed in the earlier chapters. The release of fuel gas or vapor into the ambient from leaks in pipelines conveying gaseous fuel and volatile liquid fuels at high pressures and from spills of gaseous and liquid fuels from fuel storages vessels, oil rigs and refineries, and chemical process industries could form explosive gas clouds in the atmosphere.

Gaseous, liquid, and solid substances containing elements such as carbon and hydrogen can chemically react with oxygen in the air and release energy.

The blast wave, generated by a rapid release of energy, disperses and dissipates the energy into the surrounding medium.

The word ‘explosion’ is generally used to describe events associated with a loud noise and sudden disruption of the objects at the site of its occurrence and around it.

Chemical reactions are not to the only means of obtaining rapid release of energy for the occurrence of explosions.

The overpressure and impulse at a distance \(R_s\) from an explosion were determined in Chap. 2 by assuming the energy to be released instantaneously at a point. A length scale for the energy release called as ‘explosion length \(R_0\)’ was defined, and a non-dimensional parameter \(R_s/R_0\) was used to find the values of overpressure and impulse following Sach’s scaling law. In practice, all sources of energy release would have a finite volume and the release of energy cannot be instantaneous.

Gaseous fuels and volatile liquid fuels are used for household and industrial purposes and for propulsion. They are transported by road, rail, and sea in tankers of different sizes.

When the temperature of a reactive medium is increased, chemical reactions take place in it and energy is released.