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The corrosion of steel structures in coastal areas is a major issue. Therefore, in the present study, the protection against the corrosion of structural steel is carried out by depositing 100 μm thick Al and Al-5 Mg coatings using a plasma arc thermal spray process, immersing them in 3.5 wt.% NaCl solution for 41 days (d). To deposit such metals, one of the best known processes, arc thermal spray, is frequently used, but this process has severe defects and porosity. Thus, to minimize the porosity and defects of arc thermal spray, a plasma arc thermal spray process is developed. In this process, we used normal gas to create plasma instead of argon (Ar) and nitrogen (N2) with hydrogen (H) and helium (He). Al-5 Mg alloy coating exhibited uniform and dense morphology, where it reduced more than four times the porosity compared to Al, where Mg fills the voids of the coating, resulting in greater bond adhesion and hydrophobicity. The open circuit potential (OCP) of both coatings exhibited electropositive values due to the formation of native oxide in Al, while in the case of Al-5 Mg, the coating is dense and uniform. However, after 1 d of immersion, both coatings showed activation in OCP, owing to the dissolution of splat particles from the corner where the sharp edges are present in the Al coating, while Mg preferentially dissolved in the Al-5 Mg coating and made galvanic cells. Mg is galvanically more active than Al in the Al-5 Mg coating. Due to the capacity of the corrosion products to cover the pores and defects, both coatings stabilized the OCP after 13 d of immersion. The total impedance of the Al-5 Mg coating is gradually increased and is higher than the Al, which can be attributed to the uniform and dense coating morphology where Mg dissolves and agglomerates to form globular corrosion products and deposit over the surface, thereby causing barrier protection. The defect bearing corrosion products on Al coating led to the cause having a higher corrosion rate than the Al-5 Mg coating. A total of 5 wt.% mg in the Al coating improved the corrosion rate by a rate of 1.6 times compared to the pure Al in the 3.5 wt.% NaCl solution after 41 d of immersion. [ABSTRACT FROM AUTHOR]

For the first time, using scanning electron microscopy, transmission electron microscopy, X-ray absorption near edge structure and extended X-ray absorption fine structure X-ray diffraction, it is showed that MnCO3, MnWO4, Mn3(PO4)2·3H2O, MnS and Mn(VO3)2·xH2O under the water-oxidation conditions and in the presence of cerium(iv) ammonium nitrate, are converted to Mn oxide without a high-range order. A mechanism is proposed for such conversion and as Mn oxide is an efficient water-oxidizing catalyst, it is thus a candidate as a contributor to the observed catalytic activity. [ABSTRACT FROM AUTHOR]

Arc thermal metal spray coating is very efficient process to protect the steel from corrosion in industrial, humid and saline/coastal environments. This paper incorporates the experimental results for the performance of Aluminum coating deposited on mild steel substrate by arc thermal metal spray. Different electrochemical techniques, FE-SEM, Raman spectroscopy and XRD were used to assess the performance of deposited coating. Electrochemical studies revealed the enhanced corrosion resistance properties of coating in 3.5 wt.% NaCl solution. The formation of α-Al(OH) 3 on coating substrate during exposure periods block the pores of coating and impede the penetration of corrosive species to react with substrate. [ABSTRACT FROM AUTHOR]

Arc thermal metal spray coating provides excellent corrosion, erosion and wear resistance to steel substrates. This paper incorporates some results of aluminum coating applied by this method on plain carbon steel. Thereafter, coated panels were exposed to an environment known to form stable corrosion products with aluminum. The coated panels were immersed in Society of Automotive Engineers (SAE) J2334 for different periods of time. This solution consists of an aqueous solution of NaCl, CaCl2 and NaHCO3. Various electrochemical techniques, i.e., corrosion potential-time, electrochemical impedance spectroscopy (EIS) and the potentiodynamic were used to determine the performance of stimulants in improving the properties of the coating. EIS studies revealed the kinetics and mechanism of corrosion and potentiodynamic attributed the formation of a passive film, which stifles the penetration of aggressive ions towards the substrate. The corrosion products that formed on the coating surface, identified using Raman spectroscopy, were Dawsonite (NaAlCO3 (OH)2) and Al(OH)3. These compounds of aluminum are very sparingly soluble in aqueous solution and protect the substrate from pitting and uniform corrosion. The morphology and composition of corrosion products determined by scanning electron microscopy and energy dispersive X-ray analyses indicated that the environment plays a decisive role in improving the corrosion resistance of aluminum coating. [ABSTRACT FROM AUTHOR]

We report the magnetic, electronic, and structural properties of nano-composite (Co84Zr16)Nx or CZN films prepared by reactive co-sputter deposition method. Asdeposited CZN films have shown enhancement in magnetization (Ms) with incorporation of nitrogen content, which is related to the evolution of nano-composite phase. X-ray diffraction study has confirmed poly-crystalline growth of CZN films with fcc(331) and fcc(422) phases. High-resolution transmission electron microscope study reveals that CZN films are composed of ordered and crystalline ferromagnetic Co nano-clusters, which are embedded in the nano-composite matrix. Photoemission measurements show the change in the intensity near the Fermi level most likely due to defects and shift in the core-levels binding energy with nitrogen concentration. Raman spectroscopy data show an increase in the intensity of the Raman lines with nitrogen concentration upto 20%. However, the intensity is significantly lower for 30% sample. This indicates that less nitrogen or defect states are being substituted into the lattice above 20% and is consistent with the observed magnetic behavior. Our studies indicate that defects induced due to the incorporation of non-magnetic nitrogen content play a key role to enhance the magnetization. [ABSTRACT FROM AUTHOR]

In present work, atomic diffusion processes in MgO/Fe/MgO structure is investigated. This structure is deposited by using e-beam evaporation method in ultra-high vacuum (10 −7 Torr). X-ray diffraction pattern exhibits amorphous nature of MgO layer, however, Au and Fe layers are polycrystalline in nature. Structural quality investigated using transmission electron microscopy shows the presence of short-ranged crystalline ordering in MgO layer. Oxygen atoms of this layer exhibit its interaction with Mg to form MgO, however, Fe layer exists in metal form with onset of oxidation at interface. Rutherford backscattering study shows the diffusion of atoms from upper layers to the layers underneath and to the substrate. Au atoms exhibit exponential diffusion profile in the structure, however, the compositional variation of Fe atoms is described using the combination of exponential decay and exponential growth functions. [ABSTRACT FROM AUTHOR]

Present study explores the structural, electrical and transport properties of dysprosium cation (Dy3+) substitution on (Fe+3) site in cobalt nonoferrites [CoFe 2-x Dy x O 4 (Dy(x) = 0.00, 0.05, 0.10 & 0.15)] prepared by sol-gel chemical route. X-ray diffraction pattern confirms the pure cubic spinel structure for all samples. The average crystallite size was found in the range of 49 to 72 nm with no linear variation with incresing doping concentration of (Dy3+) ions. The values of lattice parametres is found to be changed from 8.34 to 8.39 Å for pristine cobalt nanoferrite (CoFe 2 O 4) and sample having highest doping concentration i.e. Dy(x) = 0.15 respectively. The porosity observed to be decrease linearly with increasing (Dy3+) ion concentration. The electrical properties have been investigated by analyzing dielectric behaviour in the frequency range of 75 kHz- 5 MHz and temperature range of 100K– 400K. The frequency dependent dielectric behaviour at different temperatures is explained in terms of Maxwell–Wagner and Koop's phenomenological models. Ferrite with Dy(x) = 0.15 have achieved highest dielectric constant in the range of 441 to 5234 which was measured at 100K (5 MHz) and 400K (75 kHz) respectively. The electrical resistivity of each of the ferrite sample reduces with rising temperature representing the semiconductor behaviour of all ferrites which is due to the thermally triggered charge carriers hopping between (Fe2+) and (Fe3+) ions and associated with higher drift mobility. The increase in drift mobility at room temperature with increasing (Dy3+) ion concentration is considered to be a sign of improved transport behaviour. The high value of dielectric constant and low dielectric loss of all these ferrites make them suitable for the memory storage devices. [ABSTRACT FROM AUTHOR]

Abstract: In present work we have studied the effect of latent tracks on the structural and magnetic properties of nanosized zinc ferrite. These tracks were created by irradiating the system with 200MeV Ag15+ beam at the fluence of 4×1012 ions/cm2. Theoretical estimation of latent tracks shows that the track radius is ~3nm. These tracks were observed in the system with the help of transmission electron microscope. Beside these tracks, lattice distortion also appeared in the irradiated specimen. The formation of hysteresis after irradiation is due to the presence of latent tracks in the system. The change in blocking temperature after irradiation may be attributed to the change in magnetic ordering/cation inversion. Related mechanism has been discussed on the basis of thermal spike model. [Copyright &y& Elsevier]

Abstract: We investigated the magnetic behavior of nanosized zinc ferrite with the help of vibrating sample magnetometry and in-field Mössbauer spectroscopy. The nanoparticles of zinc ferrite with crystallite size ranging from 10 to 62nm were synthesized by a nitrate method. The structure and phase were determined with the help of X-ray diffraction. Attributes of cation inversion were found with the calculated values of lattice parameter. The saturation magnetization decreases with the increase in crystallite size at room temperature, while these values are almost the same at 10K for all the samples except the one with crystallite size of 10nm. The thermal magnetization measurement shows a decrease in blocking temperature with increase in particle size for these samples. The synthesized samples exhibit the presence of antiferromagnetic ordering below the blocking temperature as investigated by in-field Mössbauer spectroscopy. [Copyright &y& Elsevier]

Abstract: The present work reports on the synthesis of the Zn1−xMgxO (x = 0, 0.02, 0.05, 0.10, 0.15 and 0.20) samples by sol–gel method and the investigations on their structural, morphological and optical properties. X-ray diffraction (XRD) data analysis confirms the formation of pure ZnO phase below 10% Mg doping and MgO related phases appears in 10% doped sample indicating that phase segregation of MgO starts at x ≥ 0.10 samples. The phase segregation observed through XRD analysis is also supported by results from Scanning Electron Microscopy (SEM), Raman spectroscopy and photoluminescence studies. Furthermore, the enhancement in optical band gap, with Mg doping, from 3.1 ± 0.1 eV to 3.5 ± 0.1 eV has been observed through UV–Vis spectroscopic analysis. Above results have been discussed on the basis of defects level observed through Raman and photoluminscence studies. [Copyright &y& Elsevier]

Abstract: Soft magnetic thin films of Ni, NiFe and NiFe2O4 were prepared using reactive magnetron sputtering in various deposition conditions. Experimentally observed soft magnetic property was compared and correlated with nanocrystalline structure evolution. Ni and NiFe deposited films are textured with fcc(111) phase preferred orientation. Accordingly, grain size and lattice parameter were calculated from X-ray diffraction (111) peak line width and 2θ peak position. Addition of reactive gas oxygen in deposition process has substantial effect on crystalline structure of film. There is phase transition from the ordered NiFe (111) structure to the NiFe2O4 nanocrystalline phase. The resulting film has shown small X-ray diffraction intensity peak corresponding to (311) and (400) orientation, indicating small amount of existing NiFe2O4 phase. The mechanism has been discussed to be responsible for nanocrystallization and amorphization of NiFe2O4 films. Magnetic measurement (M-H) loop reveal soft magnetic nature of films with magnetic anisotropy. The coercivity (H c) of films is in accordance with random anisotropy model, where H c reduced with grain size. The structural transformation was supported by Fourier transforms infrared spectroscopy measurement. The films are highly smooth with surface roughness in the range of ∼0.53–0.93nm. NiFe2O4 films have shown lowest surface roughness with highest electrical resistivity values. The structural, surface, magnetic and infrared spectroscopy results are observed and analyzed. [Copyright &y& Elsevier]

Abstract: The present investigation aims to study the swift heavy ion irradiation induced effects in zinc ferrite nanoparticles through X-ray diffractometry, transmission electron microscopy and electron paramagnetic resonance spectroscopy. A series of zinc ferrite nanoparticles having different crystallite sizes ranging from 12 to 62 nm have been synthesized by using the nitrates of cations and the citric acid as the host. These samples were irradiated by 100 MeV oxygen beam with two fluences 1 × 1013 and 5 × 1013 ions/cm2. The XRD patterns show the deterioration of crystalline phase after irradiation. The average crystallite size decreases after irradiation. EPR analyses of the pristine and irradiated samples show that the changes depend on the average crystallite size of the pristine samples. Further, the pristine sample having a crystallite size of 62 nm passes through dominant changes after irradiation. It was observed that the number of magnetic centres decreases in the irradiated samples. [Copyright &y& Elsevier]

Abstract: Thin films of nickel ferrite of thickness ∼100 and 150nm were deposited by pulsed laser deposition. The films were irradiated with a 200MeV Ag15+ beam of three fluences 1×1012, 2×1012 and 4×1012 ions/cm2. X-ray diffraction showed a decrease in the intensity of peaks indicating progressive amorphisation with increased irradiation fluence. Fourier transform infra-red and Raman spectra of pristine and irradiated films were also recorded which showed a degradation of the crystallinity of the samples after irradiation. The damage cross section of the infra-red bands was determined. It was found that the two bands at 557 and 614cm−1 did not show similar behaviour with fluence. [ABSTRACT FROM AUTHOR]

Advancement in electronic and communication technologies bring us up to date, but it causes electromagnetic interference (EMI) resulting in failure of building and infrastructure, hospital, military base, nuclear plant, and sensitive electronics. Therefore, it is of the utmost importance to prevent the failure of structures and electronic components from EMI using conducting coating. In the present study, Cu, Cu-Zn, and Cu-Ni coating was deposited in different thicknesses and their morphology, composition, conductivity, and EMI shielding effectiveness are assessed. The scanning electron microscopy (SEM) results show that 100 µm coating possesses severe defects and porosity but once the thickness is increased to 500 µm, the porosity and electrical conductivity is gradually decreased and increased, respectively. Cu-Zn coating exhibited lowest in porosity, dense, and compact morphology. As the thickness of coating is increased, the EMI shielding effectiveness is increased. Moreover, 100 µm Cu-Zn coating shows 80 dB EMI shielding effectiveness at 1 GHz but Cu and Cu-Ni are found to be 68 and 12 dB, respectively. EMI shielding effectiveness results reveal that 100 µm Cu-Zn coating satisfy the minimum requirement for EMI shielding while Cu and Cu-Ni required higher thickness. [ABSTRACT FROM AUTHOR]

Stearic acid (SA) is being used as phase change material (PCM) in energy storage applications. In the present study, the microencapsulation of SA with SiO2 shell was carried out by sol–gel method. Different amounts of SA (5, 10, 15, 20, 30 and 50 g) were taken against 10 ml of tetraethyl orthosilicate (TEOS) for encapsulation. The synthesized microencapsulated PCM (MEPCM) were characterized by Fourier transform infrared spectroscope (FT-IR), X-Ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The characterization results showed that SA was successfully encapsulated by SiO2. Thermogravimetric analysis (TGA) exhibited better thermal stability of the MEPCM than SA. The enthalpy values of MEPCM were found to be unchanged even after 30 heating–cooling cycles by differential scanning calorimetry (DSC). The latent heats of melting and solidification of 50 g SA containing MEPCM were found to be highest i.e. 182.53 J/g and 160.12 J/g, respectively among all microencapsulated samples. The encapsulation efficiency values were calculated using thermal data and the efficiency was found to be highest i.e. 86.68% in the same sample. [ABSTRACT FROM AUTHOR]

Aluminum coating was deposited by arc thermal spraying process onto the steel substrate for the corrosion protection in aggressive environment. However, the arc thermal sprayed coating possesses defects in the coating. Thus, it is important to reduce the defects and enhance the corrosion resistance properties of the deposited coating using post-treatment. In the present study, we have used different concentrations of sodium phosphate mono basic (NaH2PO4) with 0.1 molar (M) calcium nitrate [Ca(NO3)2] as post-treatment solution to fill out the defects of the Al coating. It was observed by scanning electron microscopy (SEM) that 1 M NaH2PO4 with 0.1 M Ca(NO3)2 treated sample exhibited 71% reduction in defects compared to as coated samples. X-ray diffraction (XRD) was performed to determine the phases formed on the coating surface after treatments. XRD confirms the formation of sodium aluminum hydrogen phosphate (Na3Al(OH)(HPO4)(PO4)) and brushite (Ca(HPO4)(H2O)2) as composite oxides on the Al coating. Electrochemical results show that 0.5 M NaH2PO4 with 0.1 M Ca(NO3)2 treated sample has exhibited the highest charge transfer resistance and the lowest corrosion current density after 89 days of exposure in 3.5 wt.% NaCl solution. The enhancement in corrosion resistance of 0.5 M NaH2PO4 with 0.1 M Ca(NO3)2 treated sample attributed to the formation of adherent, sparingly soluble, and stable corrosion products. The volume fraction result of the corrosion products formed on 0.5 M NaH2PO4 with 0.1 M Ca(NO3)2 treated sample after 89 days of exposure in 3.5 wt.% NaCl using XRD confirms the highest amount of Bayerite (α-Al(OH)3) deposition, thus, the corrosion rate of this sample was the lowest. [ABSTRACT FROM AUTHOR]

In present study, the effect of hydrogen gas pressure on the electrical characteristics of the Pd nanoparticle embedded in the carbon matrix was investigated. The structural characterizations of the as-prepared samples were performed using synchrotron radiation x-ray diffraction (SR-XRD), and transmission electron microscopy (TEM). In-situ electrical transport studies for high concentration sample showed a slow response time (∼30 s) and the resistance versus time curves have similar behavior that of Pd thin films, whereas the lower concentration sample has a fast response time (5 s) along with peculiar response curve. The pressure dependent studies showed that spillover effect was dominant, when samples were exposed to hydrogen gas at low pressure. The superior sensing performance of the lower concentration sample was observed due to extraordinary high surface to volume ratio of nanoparticles as well as good separation provided by the carbon matrix. The spillover effect based hydrogen absorption–desorption mechanism proposed in the present study is important for understanding the hydrogen absorption in the metal nano-composite system and its application in the design of advanced materials for hydrogen gas sensors. [ABSTRACT FROM AUTHOR]

The present work investigates the magnetic behavior of Dy 3+ substituted cobalt ferrite nanoparticles. X-ray diffraction studies reveal presence of cubic spinel phases in these nanoparticles. Raman spectra of these nanoparticles show change in intensity of Raman bands, which reflects cation redistribution in cubic spinel lattice. Saturation magnetization and coercivity decrease with increase of Dy 3+ concentration in these nanoparticles. Room temperature Mössbauer measurements show the cation redistribution in these nanoparticles and corroborates the results obtained from Raman Spectroscopic measurements. Decrease in magnetization of Dy 3+ substituted cobalt ferrite is attributed to the reduction in the magnetic interaction and cation redistribution. [ABSTRACT FROM AUTHOR]

Abstract: Hydrated tungsten oxide nanoparticles have been synthesized using a simple wet chemical method while varying the concentration of HCl. XRD studies show that the variation in HCl concentration from 1M to 6M in the reaction results into gradual change in crystal structure of hydrated WO3 from hexagonal (WO3·0.33H2O) to pure orthorhombic (WO3·H2O), through a series of samples with mixed phase of the two indifferent ratios. The similar variations in the degree of hydration and phase variations have also been observed from Raman, FTIR and TGA studies. The average crystallite size of the hydrated WO3 particles was estimated to be ∼26nm from XRD line broadening and AFM studies showed the formation of spherical shaped particles for all the samples. The photochromic studies were carried out on the composite films of these materials in the polymeric matrix of polyvinyl alcohol (PVA) while exposing to UV light. The composite films show interesting variations in the photochromic behavior depending on the crystal structure of hydrated WO3 filler. The photochromic behavior has been explained on the basis of EPR spectra of hydrated WO3. [Copyright &y& Elsevier]