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Traditional study has discovered that natural materials such as wood are scarce and that synthetic materials can serve as suitable substitutes. Polymer chemicals, plant materials, chemical compounds, inorganic compounds, and other corrosion inhibitors all use metals. When technology fails, corrosion is one of the most severe consequences, causing harm to the financial system, natural resources, and people's lives. Natural materials such as wood are scarce, according to traditional research, and synthetic materials may serve as suitable replacements. Polymers as corrosion inhibitors have piqued researchers' attention from both a theoretical and practical standpoint. It has been seen from the research that natural polymer inhibitors exhibits more than 90% efficiency and good surface cover on carbon steel surface. A summary of forms of corrosion, corrosion processes, and recent work on the application of polymer inhibitors on the basis of parameters such as cost, convenience of use, environmental impact, and reliability has been reviewed.

The present work focuses on developing Gd-doped Mn spinel nanoferrites and their potential application in the photodegradation of water pollutants. The impact of Gd

A series of carbon-doped solid solutions of ceria bismuth oxide (CBO) were prepared by a solid solution method. Highly porous solid solutions crystallized in a fluorite phase and C-doped samples exhibited an enhanced band-gap and reduced lattice cell constants. Their photocatalytic activity was observed in terms of H2 and O2 production via water splitting. The maximum hydrogen production was observed for a 6% C-doped solid solution in methanolic solution, i.e. 5413.10 mmol H2 g−1 h−1 under 300 W Xe light irradiation. The 6% C-doped solid solution released maximum O2 (193.80 μmol O2 h−1 g−1) and H2 (323.00 μmol H2 h−1 g−1) from pure water under exposure to real sunlight due to the highly ordered atomic arrangement, high porosity, high crystallinity, low oxygen vacancies, and high OH-group concentration in the lattice.

A series of quadruple perovskites Ca1+xCu3-xTi4O12 was scanned by different spectroscopic and microscopic techniques. X-ray powder diffraction pattern analysis revealed that the system transformed from a monophasic (x = 0.0, 0.1 and 0.2) to biphasic (x = 0.5 and 1.0) on Ca2+ - substitution. The completely different grain morphology and the distinct signature of the UV–visible absorption band and Raman scattering peak reflect this finding well. The defects arise mainly because of the mismatch between ion and site radii. The results of positron annihilation spectroscopy to study the nature of the defects are consistent with the proposed defect-rich sample history. There are many vacancies-type defects, whose size and concentration could be characterized through the measured positron lifetimes and coincidence Doppler broadening. The results show that for x = 0.1 itself, a secondary phase may be formed. The structure-property and property-property correlations are studied.

Polycrystalline ceramic sample of novel lead manganese silicate (Pb2Mn2Si2O9: Kentrolite) was prepared by solid state reaction at 860°C. Structural, morphological, dielectric and magnetic properties of the prepared product were investigated using XRD, EDS & SEM, impedance spectroscopic and VSM techniques. Rietveld refinement of XRD and EDS & SEM analysis confirmed that stoichiometric Pb2Mn2Si2O9 crystallizes in the orthorhombic structure (space group P21221, No.: 18). Frequency dependence of impedance and optical absorption studies establishes semiconducting nature of Pb2Mn2Si2O9. Dispersion in the dielectric parameters is observed due to hopping of electrons between Mn3+↔Mn2+ and Pb2+↔Pb3+. Pb2Mn2Si2O9 displays paramagnetic character at 300K and, it undergoes multiple magnetic transitions at TN = ~67K and TG = ~17K. This compound exhibits Curie-Weiss (θP) = −70K and the best fitted μeff = 3.76μB/Mn ion shows close agreement with the magnetic moment of free Mn3+ ion. Further, this study unveils co-existence of in plane ferromagnetic order (high coercivity = ~1000Oe and low retentivity = ~0.05emu/g) and long range antiferromagnetic order in Pb2Mn2Si2O9 at low temperatures.

In this study, Zn1-xLixO (x = 0.02, 0.04, 0.06, 0.08 and 0.10) nanohexagons were prepared by sol-gel combustion route and characterized using standard techniques for understanding their crystallography, surface morphology, optical, photoluminescence and magnetic properties. Single phase wurtzite type hexagonal crystal structure of the synthesized Li doped ZnO nanoparticles was identified from the Rietveld profile refinement of the powder XRD patterns and HRTEM & SAED analysis. HRTEM micrographs and XRD peak profile analysis confirmed formation of highly crystalline Li doped ZnO nanohexagons (ZnO:Li NHs) with average crystallite size in the 20–40nm range. Formation of functional Zn(Li)–O bonds in ZnO:Li NHs was confirmed by FTIR. SEM micrographs of the prepared samples showed random shaped, uniform distribution and well dispersed grains of ZnO:Li NHs. All the ZnO:Li NHs absorbs significant light in the UV band and the band gap energy monotonically decreases with increasing Li concentration in ZnO:Li NHs. Photoluminescence spectra exhibited two characteristic emission bands in all the ZnO:Li NHs and the UV emission band showed red shifting with increasing Li concentration, which is ascertained with the optical absorbance spectrums. Visible band spectral analysis of the PL data revealed formation of neutral, mono, and divalent oxygen vacancies along with the other defects like Zn vacancy in the ZnO lattice by Li doping and synthesis mechanism. All the ZnO:Li NHs exhibited weak ferromagnetism at RT. Lattice defects and oxygen vacancies created by Li1+ ions in the host ZnO lattice play significant role in band gap narrowing, photoluminescence in orange-red region and weak ferromagnetic ordering in ZnO:Li NHs.

The current research focuses on the photocatalytic, sonocatalytic and sonophotocatalytic degradation of nigrosine dye with nitrogen-doped and undoped zinc oxide powders. The sonophotocatalytic degradation of dye was found to occur at a higher rate than during photo- or sonocatalytic processes. Nitrogen-doped and undoped zinc oxide powders were synthesized by a wet chemical method. Further, scanning electron microscopy (FESEM), electron dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), UV-VIS spectroscopy (UV-VIS) and transmission electron microscopy (TEM) were used for the characterization of N-doped ZnO. The kinetics of nigrosine degradation were also studied and the results indicated that the degradation kinetics of nigrosine followed the first-order kinetics. The rate constant and the percentage of degradation were found to be highest, 7.33 × 10−4 (s−1) and 92% respectively, for sonophotocatalytic process after 90 min of reaction. Due to an increase in the available surface area or active sites of the catalyst, a higher rate constant and degradation efficiency was observed in the sonophotocatalytic system than in the photocatalysis system.

Nanoparticles of pure ZnO and monovalent, divalent & trivalent doped Zn0.96T0.04O (T: Li+, Ca2+& Gd3+) were prepared by the nitrate-citrate based sol-gel method. Powder XRD, TEM and photoluminescence data analysis confirmed single phase formation of pure ZnO, Zn0.96Li0.04O, Zn0.96Ca0.04O and Zn0.96Gd0.04O nanocrystals in the wurtzite type hexagonal lattice with surface and intrinsic crystal defects. UV–Vis–NIR optical absorption measurement demonstrated significant optical light absorption in the visible and UV bands for all the samples. A photo absorption peak below 380 nm is observed in all the four samples. The band gap energies were estimated to be 3.03eV, 2.78eV, 2.90eV and 2.79eV for ZnO, Zn0.96Li0.04O, Zn0.96Ca0.04O and Zn0.96Gd0.04O respectively. Monovalent and trivalent doping in ZnO induces reduction in the band gap energy and increment in the refractive index. 325 nm excited photoluminescence spectrums of pure and doped ZnO samples displayed a peak in the UV region and a broad peak in the visible band. Ca, Li and Gd doping in ZnO leads to red shifting of the UV emission band by substantial decrement in the band-gaps. Deconvoluted PL data analysis attests presence of various types of defects in the ZnO lattice which leads to strong electronic emission in the visible band. Computed values of CCT were found to be below 4000 K in these nanocrystalline samples, which makes them suitable material for the household optoelectronic devices. This study suggests that monovalent (Li+) doping in ZnO is better choice for tuning the optical and photoluminescence properties for their possible utilization in light harvesting and energy conversion applications.

This article describes synthesis of superparamagnetic fcc-CaFe2O4 nanoparticles by a metal nitrate-citrate monohydrate sol–gel route and characterization using X-ray diffractometry, Raman spectroscopic, UV–Vis–NIR optical absorption spectroscopic, Mossbauer spectroscopy, dielectric and SQUID magnetometry measurements. Rietveld refinement of the X-ray diffraction pattern and observation of active A1 g, T2 g & Eg modes in the Raman spectrum confirmed formation of single phase CaFe2O4 nanoparticles in the spinel ferrite type fcc structure without impurity. Mossbauer and Rietveld data analysis revealed that nanocrystalline CaFe2O4 is dominantly an inverse ferrite in which 85% Ca atoms preferentially occupy the octahedral site in the fcc symmetry and the Fe ions are in high spin Fe+3 state. Nanocrystalline CaFe2O4 significantly absorbs optical light below 500 nm and the direct band gap energy is estimated to ~1.83 eV, which is higher than 1.26 eV reported for orthorhombic CaFe2O4. Temperature and field dependent magnetic studies showed that fcc-CaFe2O4 nanoparticles exhibit superparamagnetism at room temperature with high saturation magnetization of 1.07μB. The blocking temperature is ~53 K at 1000 Oe and ~72 K at 500 Oe clearly shows lowering of blocking temperature at higher magnetic field. Interestingly below the blocking temperature at 20 K, CaFe2O4 nanoparticles behave as non collinear soft-ferrimagnetic material with a saturation magnetization of 1.16 μB, coercivity of 150 Oe and remanence of 4.45 emu/g. The magnetic momenta of Fe+3 ions residing at the octahedral sub-lattice are canted at ~25 °.

Impact of hydrogenation on the structural, dielectric and magnetic properties of half-doped La0.5Ca0.5MnO3 manganate have been investigated. Polycrystalline sample of La0.5Ca0.5MnO3 was prepared through solid state reaction at ~ 1300 °C. Subsequently, the prepared sample was annealed at 600 °C for 6 h in a continuous flow of hydrogen gas in a tubular reduction furnace. Single-phase orthorhombic structure of the hydrogenated La0.5Ca0.5MnO3 in the space group Pnma was confirmed by Rietveld refinement of PXRD and FTIR analysis. SEM micrographs revealed well resolved grains of ~ 2 μm in a good crystalline sample. Hydrogenated La0.5Ca0.5MnO3 showed a sharp optical absorption peak in the UV range with a bandgap energy of 4.96 eV. Hydrogenation of La0.5Ca0.5MnO3 leads to significant reduction in the magnitude of dielectric constant and tangent loss at room temperature. Paramagnetic character of La0.5Ca0.5MnO3 at 300 K is retained upon the hydrogenation but the low temperature magnetic properties get modified dramatically. Temperature and field dependent magnetization measurements showed that hydrogenated La0.5Ca0.5MnO3 undergoes paramagnetic to antiferromagnetic transition at TN = ~ 110 K and in a disordered magnetic phase below 50 K. Systematic enhancements in the magnitude of saturation magnetization (Ms), coercivity (Hc), remanence (Mr) and squareness ratio at 50 K and 20 K indicate for the coexistence of antiferromagnetic and weak ferromagnetic order due to competitive magnetic exchange interactions between Mn3+ and Mn4+ ions. This study shows that hydrogenation plays key role in the modification of dielectric and magnetic properties of La0.5Ca0.5MnO3.

This article presents an in-depth study on the structural, morphological, electrical and magnetic characterizations of two new phases of apatite-type lanthanide silicates. Polycrystalline samples of neodymium and samarium–manganese silicates (Nd4MnSi3O13 and Sm4MnSi3O13) were synthesized using a high-temperature solid-state reaction route. Rietveld profile refinement of X-ray diffraction data and FTIR analysis revealed that Nd4MnSi3O13 and Sm4MnSi3O13 crystallize in the single-phase apatite-type hexagonal structure with P63/m space group. Scanning electron micrographs showed good crystallinity in the two silicate samples, and the average size of the grains is found to be in submicrons. Frequency dependence of dielectric constant and tanδ for Nd4MnSi3O13 and Sm4MnSi3O13 showed systematic decrement with frequency. DC conductivity studies are indicative of low activation energy and semiconducting nature of Nd4MnSi3O13 and Sm4MnSi3O13. At room temperature, both the silicates exhibit dominant paramagnetism; however, short-range one-dimensional ferromagnetic chains coexist in the paramagnetic state of Nd4MnSi3O13 and Sm4MnSi3O13.

The electronic structures of stoichiometric, single phase, coarse-grained CaCu3-xTi4-xFe2xO12 (x = 0.0, 0.1, 0.3, 0.5 and 0.7) polycrystalline ceramics have been investigated using powerful X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopic measurements, performed near Ti L3,2 and Ti K- edges, registered at 300 K. The absence of pre-edge structures in Ti L3,2 – edge are indicative of a departure from octahedral cubic symmetry, while the observed small increase in the intensity of absorption peaks has been attributed to increasing spin-orbital coupling with increasing Fe-content (x) in the system. The presence of a pre-edge feature in Ti K- edge spectra confirms the presence of octahedrally coordinated Ti4+ ions in the system. The EXAFS spectra measured at Ti K- edge indicate the first shell Ti—O bond distances to be nearly 1.56 A in the sample without Fe. With the increase in the Fe- concentration (x), the Ti-O distance shows a slight reduction. The second shell Ti-Ca bond distance comes out to be nearly 2.6 A which decreases with an increase in the Fe - concentration.

In this study, the correlation between the concentration of dopant ions and oxygen vacancy defect of Sm-doped CeO2 Nano-particles (NPs) were investigated systematically by X-ray diffraction (XRD), Ultraviolet–visible-Near Infrared spectroscopy (UV–Vis–NIR) and Surface-enhanced Raman spectroscopy (SERS). The nano-crystalline C e 1 − x S m x O 2 (x = 0.00, 0.02, 0.04, 0.06, 0.08 and 0.10) samples were synthesized using co-precipitation chemical route. The XRD measurements revealed that Sm3+ ions are successfully incorporated at the Ce4+ ion sites in the face centered cubic (fcc) lattice of CeO2 NPs. The high-resolution transmission electron microscopy (HRTEM) and Selected area electron diffraction (SEAD) patterns were analyzed to study the surface morphology, crystallinity, atomic structure of the samples. The average particle size calculated with TEM images was obtained in the range of 5–8 nm for C e 1 − x S m x O 2 samples for all the doping concentrations. The UV–Vis–NIR spectroscopy and Surface-enhanced Raman Spectroscopy were analyzed to investigate the optical properties and defect structure in these NPs. The UV–Vis–NIR spectroscopy measurements revealed that due to aggregation of particles the optical band gap energy was varied with fluencies of Sm3+ ions as well as due to particle size variations of NPs. Peak asymmetry and broadening of Raman active mode further ascribed the presence of oxygen vacancy (whether extrinsic or intrinsic), which were varied with the fluencies of Sm3+ ions in CeO2 NPs. This paper presented a systematic study on the fluencies of Sm doping in CeO2 nano-particle lattice to understand the role of vacancies, intrinsic and extrinsic oxygen vacancies and their effect on tailoring the structural and optical properties of doped CeO2 nano-particles for various applications like luminescent materials, oxygen transportation, catalysts, ultraviolet fuel cells, corrosion prevention etc.

We report, the effect of heat treatments slow cooling, rapid thermal cooling (quenching) and microwave-assisted heating, on structural, microstructural and J – E characteristics of CaCu3Ti4O12 polycrystalline ceramic. Rietveld refinement of X-ray data confirms the emergence of the mono-phasic cubic perovskite structure, diffraction line broadening and change in the relative intensity of diffraction peaks while scanning electron microscopy revealed completely different grain morphology. The observed modifications have been discussed in detail. The strong nonlinear J – E characteristics over the wide temperature range (300–823 K) indicated the existence of a Schottky-type electrostatic potential barrier at the grain boundaries. The parameters, nonlinear coefficient, threshold electric field, potential barrier height suggest suitability of the materials for low voltage varistor applications.

The present study reports the effect of Fe-doping on the structural, optical, magnetic and electronic properties of polycrystalline CeO2 (for 5 and 10% doping concentration of Fe-cation) samples synthesized by low-temperature solid-state reaction method. Rietveld refinement of the X-ray diffraction patterns establishes fluorite-type face-centred cubic structure of the Fe-doped CeO2 samples and also confirms successful incorporation of Fe ions in the CeO2 lattice. The UV–Vis–NIR absorption spectra displays reduce band gap energy with rising fluency of Fe-ions, which confirm red shifts in the Fe-doped CeO2 samples. The electronic structure of the pure CeO2 and Fe-doped CeO2 polycrystalline samples have been investigated by X-ray photoemission spectroscopy (XPS). The XPS spectra of Ce 3d reveals the reduction of Ce4+ to Ce3+ states Fe-doped CeO2 samples, which are well supported by the Fe 2p and O 1s spectra. Pure polycrystalline CeO2 displays diamagnetic behaviour at room temperature. Interestingly, 5% Fe-doped CeO2 sample displays S-shape hysteresis loop and establishes room temperature ferromagnetism, whereas, 10% Fe-doped CeO2 sample shows weak ferromagnetic behaviour. A decrement is observed in the magnetization on increasing the doping concentration. The possible reason for ferromagnetism in the Fe-doped CeO2 samples may be incorporation of oxygen vacancies, which are further discussed using F-centre exchange mechanism and double exchange interaction. These experimental findings offer potential opportunities for spintronics and optoelectronics applications by integrating them into device structures and evaluating their performance as a function of their material properties.

Structural, Optical, Magnetic and Electronic-state properties of co-precipitation method synthesized pure CeO2 and Ce 1 − x Fe x O 2 nanomaterials have been analysed in pursuit of room temperature ferromagnetism and creation cum storage of oxygen vacancies for technological applications. Intact cubic fluorite structure after doping with presence of defects and oxygen vacancies are confirmed by XRD and Raman analysis. The grain size distribution of all the nanomaterials in 4-5 nm range is discussed with TEM images. Core level XPS spectra of Ce-3d, Fe-2p and O-1s are discussed to account for the change in valence state of cerium ion from Ce4+ to Ce3+. Oxygen vacancies generated due to substitution of Ce4+ by Fe3+ ion at Ce ion sites are responsible for observed weak ferromagnetism. The results for weak ferromagnetism in pure CeO2 and Ce 1 − x Fe x O 2 samples are explained by correlating the F-center exchange mechanism with the formation of F+ center complexes Fe 3 + ( ↑ ) − V O ( ↓ ) − Ce 3 + ( ↑ ) and Ce 3 + ↑ − V O ↓ − Ce 4 + ( ↑ ) enjoined by oxygen vacancies.

Corrosion is distruction of the metal surface due to the interaction with its environment. It is due to the exposure of the metal with a gas and a fluid and it turns into a significant issue as it causes enormous monetary misfortune. To overcome risky and hazardous corrosion effect, a specialists and researchers proposed some technique to control corrosion such as utilization of chemicals as corrosion inhibitors, surface coatings, cathodic and anodic protection, adjust destructive climate etc. Among all one of the very important technique is to use corrosion inhibitor in industrial pickling process. Most of the corrosion inhibitor are having toxic behaviour and to overcome that natural inhibitors like plant extract and low toxic materials like terminated medications can be used to follow the principles of the environmental safety and sustainability. Writing survey uncover those different sorts of medications (Antibacterial, Antifungal, Antibiotic, Anti-malarial, Analgesic, Anti-depressant, Anti-hypertensive, Antihistamine) have been viably energetic as plausible inhibitors for diminishing the impact of consumption on metals and compounds. The up-and-coming segments convey complete outline of the utilization of medications and green consumption inhibitors and the writing on their corrosion restraint considers.

This work is aimed to understand influence of 10% Ca doping on the structural, optical, dielectric and magnetic behavior of half doped Zinc-Cobalt nanoferrites. Zn0.5−xCa0.1Co0.4+xFe2O4 (x = 0.0, 0.05 & 0.1) nanoferrites with crystallite size in 10–13 nm range were synthesized through a sol-gel auto-incinerated route. Rietveld profile refinement of PXRD patterns, observation of spinel ferrite type fcc Laue rings in SAED patterns, Raman modes (A1g,T2g & Eg) and metal-oxide (υ1 & υ2) bonds in 400–600 cm−1 IR range illustrated formation of single phase mixed valent spinel type fcc nanoferrites. In these nanoferrites Zn2+ ion resides at tetrahedral (TA) site, while Co2+ & Ca2+ ions preferentially fill the octahedral OB site and Fe3+ ion occupy both TA & OB sites. Moderate optical absorbance in blue color region and strong absorbance in the lower UV region is observed in these nanoferrites, which is owing to presence of mixed valent ions at the OB and TA sites respectively. 10% Ca doping in these half doped Zn-Co nanoferrites led to considerable decrement in the band gap energy (Eg) and turning them to semiconducting state (Eg in 2.5–2.3 eV range). In these nanoferrites hopping of electrons between divalent Fe2+, Ca2+, Zn2+, Co2+ & trivalent Fe3+ & Co3+ cations led to systematic decrease in the dielectric parameters with frequency. These nanoferrites exhibited superparamagnetism with a high magnetic moment (~ 2.9–3.0μB/f.u.) at room temperature. Systematic enhancements in saturation magnetization (Ms), coercivity (Hc), remanence (Mr) and squareness ratio at low temperatures revealed changing of superparamagnetic character to soft ferrimagnetic state of these nanoferrites. At 20K, highest value of Ms = 119 emu/g was observed for Zn0.5Ca0.1Co0.4Fe2O4 nanoferrite, while highest Hc = 2911 Oe & Mr = 61.0 emu/g were recorded for Zn0.4Ca0.1Co0.5Fe2O4 nanoferrite. Thus, a moderate 10% Ca2+ ion incorporation in Zn0.5−xCa0.1Co0.4+xFe2O4 (x = 0.0, 0.05 & 0.1) nanoferrites is emerged as an effective route for obtaining superparamagnetic nanoferrites with high magnetic moment and reduced band gap energy. Unique magneto-optical characteristics of Zn0.5−xCa0.1Co0.4+xFe2O4 (x = 0.0, 0.05 & 0.1) nanoferrites would project them as a good material for opto-magnetic, drug carrier, biomedical contrast agent and magnetic storage applications.

Understanding of origin of ferromagnetism in dilute magnetic oxides (DMO's) has become one of the most challenging research problems in condensed matter physics. Here we are reporting a detailed study of magnetic properties and electronic structure of two 5% Co-doped ZnO samples (the as-prepared sample Zn0.95Co0.05O and the hydrogenated sample Zn0.95Co0.05O:H). The as-prepared sample is found to be paramagnetic while through hydrogenation, we observed inducement of remarkable ferromagnetism in it. The H-mediated magnetic transition is accompanied by electronic structure modifications with no structural deviations. To get in-depth information into electronic structure correlations of the observed ferromagnetism, we have investigated their electronic properties in detail. For this purpose, we have employed the site-selective and element-sensitive X-ray-absorption spectroscopy (XAS) in the vicinity of the Cobalt L2,3 edge, the oxygen K edge, and the Zinc L3 edge using synchrotron radiation. The Co L2,3 edge spectra clearly show that Co dopants reside at the Zn sites for both these samples and that they are tetrahedrally coordinated with the ligand O atoms. Very minor changes are observed in the Zn L3 edge spectra. However, the O 1s edge spectra display dominant additional components in the ferromagnetic hydrogenated sample Zn0.95Co0.05O:H, not observed in the as-prepared non-magnetic sample Zn0.95Co0.05O. We conclude that the observed spectral features can be attributed to the presence of O vacancies and the hybridization of Co 3d states with O 2p vacancy states. These two factors together are likely to play important role in inducement of ferromagnetic ordering in this Co-doped ZnO system. However, which of these two weighs more in this mechanism, cannot be pinpointed and more studies are required in this regard.

This work is aimed to understand magnetic behavior at low temperature of nano particles of Zn0.5Co0.5Fe2O4 ferrite. The sample has been synthesized by using a Sol Gel method. Rietveld refinement of XRD data confirms the single-phase cubic spinel crystal structure with lattice constant a = 8.41 A. The average crystallite size ~30 nm has been determined by Debye-Sherer formula. The field emission scanning electron microscopy micrographs show the spherical nature of nanoparticles and energy dispersive X-ray measurement confirms the elemental composition in the sample. Also, the Mapping of the sample has been performed which shows the appropriate distribution of elements in the sample. Magnetic measurements have also been performed in variable applied magnetic field (up to 5 T) and temperature (up to 2 K). The zero field cooled, field cooled curves have been measured under the applied magnetic field 50, 100 and 500Oe. The competition between thermal and magnetic energy has been studied in detail. In addition, the M-H loop has been measured at different temperatures i.e. 300 K, 200 K, 120 K, 100 K, 50 K and 5 K, by applying a variable external magnetic field up to ±5 T. The M-H loop is observed continuously decreasing with increasing temperature. The Bloch’s law fitted in the saturation magnetization which gives Mo = 113.045emu/gm, T0 = 547.45 K and α B = 1.5. Also, the Kneller’s law fitted in variable coercivity with respect to temperature which suggests that the blocking temperature ~360 K (i.e. above the room temperature). Furthermore, the dM/dH peak height is increasing with increasing temperature which indicates the good magnetic state of the sample.

Polycrystalline sample of novel Cobalt-akermanite: Ca2CoSi2O7 was synthesized using solid state reaction method. Room temperature powder X-ray diffraction and dc-electrical conductivity studies confirmed good quality of the synthesized sample in single phase tetragonal structure with space group: P 4 21m. Low value of activation energy estimated from the dc-conductivity study indicates insulating behavior of this compound. Magnetic study showed a paramagnetic nature of Ca2CoSi2O7 at room temperature and antiferromagnetic nature below TN=5.6 K. In this compound weak ferromagnetism co-exist with antiferromagnetism below Neel temperature. Ca2CoSi2O7 displays magnetic field induced weak ferromagnetic transition around 7.4 K. Antiferromagnetic interactions occurs between the nearest neighbor Co2+ ions, as indicated by the negative sign of Weiss constant, θP=−22.7 K. Estimated value of the effective magnetic moment, μeff=4.75μB is found to be larger than the spin-only value of magnetic moment of Co2+ ion in the tetrahedral coordination having three unpaired electrons. These results, suggest that the orbital contribution to magnetic moment in this compound cannot be neglected and the electric polarization through spin dependent p-d hybridization can be expected in Ca2CoSi2O7.

In this research work, we have synthesized pure and Ce1-xNdxO2 (x = 0.08 and 0.10) nanomaterials using microwave assisted co-precipitation method. The structural and optical properties have been studied using X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Raman spectroscopy. The XRD and Raman spectroscopy results are in good agreement for cubic fluorite structure and phase purity with Nd-doping concentration in CeO2. From TEM results we have measured the particles size in 6.55 nm-7.39 nm range with spherical morphology. The Raman bands show red shift with increased Nd-doping on the Ce lattice site. The longitudinal, transverse and Frenkel type defects can be observed to be more pronounced with increased doping. The absorption band of UV-Vis-NIR spectra below 400 nm is showing red shift, which indicates Ce3+ oxidation state with incorporation of Nd3+ ions. The results are explained to show promotion of oxygen vacancy and defects with the increased Nd-doping; make them promising material for optoelectronics and photocatalytic applications.

Anatase-TiO2 nanoparticles were prepared using titanium sulphate through a sol-gel reaction method and calcined at 500°C. Powder X-ray diffraction study showed single phase anatase type tetragonal structure of the TiO2 nanoparticles with an average crystallite size of ∼10 nm. The band gap energy estimated from UV-Vis-NIR absorbance are found to be ∼2.42eV and ∼2.64eV for the as prepared and calcinated TiO2 nanoparticles respectively. Photoluminescence spectra and CIE chromaticity analysis shows that the principle components in the visible emission band are cyan and orange color for the as prepared and annealed TiO2 respectively. CCT values of 4817K and 3760K are estimated for the as prepared and annealed TiO2 nanoparticles respectively.

To minimize the pressure of growing demands of bioenergy crops and remediating polluted sites in a wide-range of environmental stressed conditions are some major issues and have increased interest worldwide to solve both the problems by using reed canary grass. Besides, this perennial grass has good potential to contribute a number of desirable attributes, such as improving water quality, limiting soil erosion, having lower nutrient requirements, and increasing the organic matter in the soil system to become adaptive in various agricultural practices. In this chapter, the characteristics of reed canary grass (Phalaris arundinacea L.) with regard to its potential use as a viable candidate for phytoremediation of polluted sites with biofuel production potential are discussed. The biomass production of reed canary grass on a variety of derelict lands (i.e., marginal lands, degraded lands, contaminated sites, underutilized and neglected lands, etc.) is a potential offer to produce biofuel without reallocating land from food production systems, avoiding the socio-environmental conflicts linked with biofuel production. Therefore, the reed canary grass is a best asset for phytoremediation of contaminated lands with biofuel production on wide-ranging contaminated sites.

Nanocrystalline CaFe2O4 ferrite sample was synthesized through a sol-gel reaction route and annealed at 100°C. Powder XRD, Raman spectroscopy, SQUID magnetometry and dielectric measurements were performed for the thorough characterization of CaFe2O4. XRD and Raman analysis showed formation of single phase nanocrystalline CaFe2O4 in the fcc symmetry with an average particle size of ∼70 (±10) A. Dielectric parameters of CaFe2O4 swiftly decrease in the low frequency range and remain almost constant at higher frequencies. CaFe2O4 display superparamagnetism at room temperature with a high saturation magnetization of ∼27emu/g and the M-H curve is well adjusted with a Langevin function for an average crystallite size of ∼60 (±9) A. M-H curve recorded at 5K showed ferrimagnetic behaviour of CaFe2O4 with a saturation magnetization of 30emu/g, coercivity of 300Oe and 9emu/g remanence. ZFC and IFC modes of magnetization depart each other well above the blocking temperature and the blocking temperature was found to be ∼49 K at 1000Oe and ∼126 K at 50 Oe.

7% Mg doped ZnO nanoparticles were synthesized using sol-gel route and characterized by powder X-ray diffraction, UV-Vis-NIR absorption and Photoluminescence spectroscopic measurements. Rietveld refinement of XRD pattern confirmed single phase formation of Mg doped ZnO in the wurtzite type hexagonal structure. The optical absorption spectra showed significant light absorption in the UV and visible regions. Band gap energy were estimated to be 2.99 (±0.2) eV and 2.82 (±0.3) eV for the as prepared and 4500C annealed Zn0.93Mg0.07O nanoparticles respectively. Photoluminescence spectrum of the two 7% Mg doped ZnO samples showed two characteristic UV and visible band emission peaks. PL analysis revealed that as prepared Zn0.93Mg0.07O dominantly emits in the red-orange region, while Zn0.93Mg0.07O annealed at 4500C emits more in the red region and presence of various types of lattice defects such as oxygen & zinc vacancies and interstitials.. The correlated color temperature was found to be ∼2935K.

In this manuscript, ZnO nanoparticles (NPs) doped with 8 and 10 wt. % Sm2O3 were prepared using Co-precipitation method and annealed at 400 °C. The prepared samples were characterized using X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV-Vis-NIR spectroscopy and soft X-ray absorption spectroscopy (SXAS) techniques. The surface morphology and particle size distribution were studied using TEM and nano-crystalline samples having particle size of the order of 21-23 nm with spherical shape. The results of UV-Vis spectra indicate that the band gap decreases for 8 wt. % Sm2O3 concentration and further it increased for 10 wt. % Sm2O3-doped ZnO NPs but with negligible change from the band gap value of pure ZnO NPs. The electronic structure properties of the prepared samples characterized using X-ray absorption spectroscopy measurements and the analysis showed the presence of oxygen vacancies and one oxidation state of Sm3+. These NPs can be used for various application such as photo-catalytic, gas sensors, varistor ceramics etc.

Magnesium oxide (MgO) nanoparticles were synthesized using nitrate-citrate sol-gel route and the sample yield was annealed at 300°C, 450°C and 700°C for getting size distribution. Structural characterization was done by powder X-ray diffraction (XRD) measurements. Rietveld profile refinement of XRD patterns confirmed formation of single phase MgO nanoparticles in the NaCl type fcc structure without any impurity within the detection limit. Annealing of the MgO nanoparticles up to 700°C does not disturb the fcc structure. The average crystallite size slightly increases when the annealing temperature was increased from 300°C to 450°C, while further increase in the annealing temperature to 700°C leads to a swift increment in the particle size and drastic decrease in the lattice strain and better crystallinity of MgO.

Nanocrystalline cobalt ferrite (CoFe2O4) was synthesized through a sol-gel reaction route and characterized by powder XRD and SQUID magnetometry measurements. Rietveld profile refinement of XRD pattern confirmed formation of single phase nanocrystalline CoFe2O4 in the fcc symmetry with an average particle size of ~16nm. CoFe2O4 display soft ferrimagnetic behavior at 300K with a saturation magnetization of ~74emu/g, remanence of ~27emu/g and coercivity of 1.66kOe. M-H curve recorded at 5K showed wasp-waisted hysteresis loop with a saturation magnetization of 80emu/g, very high coercivity of 13.52kOe and 59emu/g remanence. Temperature dependence of ZFC and IFC modes of magnetization are suggestive of superspin glass state below 100K in CoFe2O4 nanoparticles. Superposition of superspin glass and superparamagnetic phases in the CoFe2O4 lattice at 5K leads to the wasp-waisted hysteresis loop.

TiO2 nanoparticles were synthesized by co-precipitation method and annealed at 500°C and 700°C in air. The samples were characterized by powder X-ray diffractometry (XRD), Raman, UV-Vis-NIR and Photoluminescence spectroscopic measurements.XRD and Raman analysis confirmed that both the samples possess single phase anatase type tetragonal structure. The average crystallite size of the 500°C and 700°C annealed TiO2 nanoparticles were estimated to be 10±3 and 14±4 nm respectively. Optical absorption study showedthat in both the samples maximum photo absorption take place below 400 nm and the band gap energy were found to be 2.87 (±0.2) eV and 2.37 (±0.3) eV for 500°C and 700°C respectively. Photoluminescence spectrums of the two samples displayed strong emission in the visible band with multiple electronic transitions in the 400-850nm range, which suggests presence of various types of lattice defects in the TiO2 matrix. Increase in annealing temperature leads to red shifting of the visible band and reduction of band gap energy. Computed values of CCT were found to be 1992K and 1980K for 500°C and 700°C respectively, which makes them suitable material for the light harvesting optoelectronic devices.

We report here the impact of Gd substitution on structural, optical, photoluminescence and magnetic properties of Zn1−xGdxO (x = 0.02–0.10) nanocrystals. Rietveld refinement of PXRD patterns, SAED and FTIR analysis revealed that Zn1−xGdxO nanoparticles crystallize in single phase wurtzite type hexagonal symmetry. HRTEM & SEM analysis confirmed good crystallinity of Zn1−xGdxO nanocrystals with a wide size distribution in 10–40 nm range. Concentration of Gd3+ ions at the Zn site causes a systematic reduction in the average crystallite size of Zn1−xGdxO nanocrystals. UV-Vis-NIR and photoluminescence spectroscopic studies showed decrement in band gap energy and suppression of UV emission (391–416 nm) with Gd concentration in Zn1−xGdxO. Analysis of the visible band emission spectra demonstrated that 325 nm photoexcited Zn1−xGdxO nanocrystals emit light in the orange-red region due to formation of complex defects in the ZnO lattice. M-H curves of 2% and 4% Gd doped ZnO nanocrystals recorded at 300 K showed thin ferromagnetic hysteresis loop (almost equal Mr =~1.8 memu/g and Hc=~210 & ~136 Oe for 2% and 4% Gd doped ZnO respectively) at lower magnetic fields but in the high field range, the magnetization responded linearly with the applied magnetic fields and, thus establishes coexistence of paramagnetic and weak ferromagnetic ordering in 2% and 4% Gd substituted ZnO nanocrystals. The higher 6%, 8% and 10% Gd substituted ZnO nanocrystals are found to be paramagnetic at 300 K. At 5 K, all the samples showed S-shaped M-H curves with negligible coercivity & retentivity and the magnetization monotonically incremented (5–25 emu/g) with increasing Gd concentration in Zn1-xGdxO. Superparamagnetic clusters and antiferromagnetic states coexist in Zn1−xGdxO nanocrystals at 5 K. Magnetic and optical properties of Zn1−xGdxO nanocrystals are suitable for magneto-optoelectronic applications.

In the present work, photo-Fenton degradation of Sunset Yellow FCF under visible light was carried out by using copper loaded bentonite and hydrogen peroxide. The photocatalyst was prepared by loading copper ions on bentonite by wet impregnation method. The rate of photocatalytic degradation of dye was measured spectrophotometrically by measuring absorbance of the reaction mixture at regular time intervals. The effect of various parameters such as pH, concentration of dye, amount of photocatalyst, amount of H 2 O 2 and light intensity on the reaction rate has also been studied. Characterization of photocatalyst has been done by IR spectroscopy, scanning electron microscopy and X-ray diffraction. The Chemical Oxygen Demand (COD) of the reaction mixture has been determined before and after treatment. A tentative mechanism involving OH radical as an oxidant for degradation of dye has also been proposed. Involvement of OH radicals as an active oxidizing agent has been confirmed by using isopropanol and butylated hydroxy toluene (BHT) as radical scavengers. It has been observed that the rate of reaction is drastically reduced in the presence of these scavengers. The rate of reaction is much retarded by using BHT as compared with isopropanol.

Inspired by the ancient art work and recent scientific advances in inorganic blue pigments, we have synthesized polycrystalline ceramic samples of barium copper tetrasilicate (BaCuSi4O10) and strontium copper tetrasilicate (SrCuSi4O10) using solid state reaction route to understand their crystallography, magnetism and optical behaviour. Powder X-ray diffraction patterns confirmed single phase tetragonal crystal structure with space group P4/ncc for both the pigment samples. The unit cell lattice parameters and other structural parameters of these samples were determined using the Rietveld profile refinements of powder diffractograms. Both of these blue pigments show swift optical absorption below 300 nm and considerable absorption in the visible and infrared regions. The obtained values of band gap for BaCuSi4O10 and SrCuSi4O10 were found to be 3.61 and 3.52 eV respectively. Temperature and field dependent magnetization measurements are suggestive of paramagnetic state at room temperature and superparamagnetic state at low temperatures in both these compounds. The estimated values of effective magnetic moments were found to be 1.833 and 1.91 μB for BaCuSi4O10 and SrCuSi4O10 respectively. Interestingly these obtained values of magnetic moments are very close to the theoretical value of 1.73 μB for Cu2+ ion.