Manganese Films Research Articles

Room Temperature Detection of Chlorpyrifos Using Thermally Oxidized Manganese and Copper Thin Films

The usage of pesticides has increased rapidly over the past three decades to boost crop production and meet the global food demand. According to UN FAO, about 66% of the countries have reported an average increase in pesticide consumption of about 1.85 kg hectare−1 between 1990 and 2019. Chlorpyrifos is a widely used but hazardous pesticide, popular for domestic and agricultural applications. Real-time monitoring of Chlorpyrifos is necessary for its safe application due to its toxicity, even at the residue level. In this work, an attempt has been carried out to detect chlorpyrifos at room temperature using thermally oxidized manganese and copper thin films. Thermal oxidation of thin films has been carried out under air ambient at different temperatures ranging from 400 °C to 550 °C for manganese and 500 °C to 800 °C for copper thin films. Morphological investigation depicts nanobar-like morphology and irregular-sized clusters for various oxidation temperatures of manganese oxide thin films, and granular-like morphology with an increase in grain size has been observed for increasing oxidation temperature. Structural investigation using the XRD technique depicts the evolution of various phases of manganese oxide thin film and a single monoclinic phase for copper oxide thin film. Further, the RMS roughness of the manganese and copper film was found to vary differently with the rise in oxidation temperature. Copper oxide thin films have shown higher chlorpyrifos sensing response with sensitivity than thermally oxidized manganese thin films better sensing response towards chlorpyrifos. The sensitivity at room temperature is found to be around 30 and 250 for manganese oxide and copper oxide thin films, respectively.

The energy band gap of the manganese oxide pyramidal nanostructures

In this paper, we report on the number of nanorods changing in the structural and optical properties of manganese oxide pyramidal nanostructures with a square cross-section deposited on the glass substrate. The structural and optical properties of the manganese films were investigated. The X-ray diffraction (XRD) analysis showed manganese oxide pyramidal nanostructures with 10, 9, and 8 nanorods that have Mn3O4, Mn3O4, and Mn2O3 phases, respectively. The optical measurement for manganese oxide thin films showed the transmittance and the energy band gap in the ultraviolet and visible regions. The transmittance decreases with increasing the number of nanorods. In addition, the optical band gap increases from 2.64 eV to 2.88 eV with increasing the number of nanorods.

Paleosols record dry and humid paleoenvironments during the Upper Pleistocene in the Brazilian Pantanal

Information on Quaternary landscapes and paleoenvironmental changes in the interior of Brazil are scarce. One of such areas, particularly sensitive to these variations, is the modern tropical Pantanal wetland, whose alluvial deposits record paleoenvironmental and paleoclimatic changes during the late Quaternary. Based on detailed pedological and sedimentological descriptions, stimulated optical luminescence dating and analytical data we described a well-exposed sedimentary succession that crops out in slope terraces of the Aquidauana River, located in the southern area of the Pantanal. We interpret environmental changes that have occurred since the beginning of the Upper Pleistocene, and which affected sedimentation and biogeochemical processes. Basal deposits comprise cross-stratified sands, which record active fluvial sedimentation from ∼106 to ∼70 ka, a period of probable increased river discharge. Fluvial channel facies are overlaid by pedogeneized floodplain deposits, in which we recognized a pedocomplex composed of a sequence of three late Pleistocene truncated paleosol profiles and a Holocene soil profile. The two lower paleosols are Vertisols with mottling, slickensides, rhizolites and septarian glaebules of carbonate. These characteristics indicate prolonged drought periods under semi-arid to arid climates ca. ∼70 and ∼30 ka. The upper paleosol profile is a Planosol (Ultisol) with block structure, waxiness, iron glaebules, and manganese films, pointing to prevailing humid climates during the terminal Pleistocene (since ∼30 ka). Covering this truncated Planosol is a layer of fine to medium-grained Holocene sands, with development of a horizon A of an Arenosol (Entisol). These paleoenvironmental changes correlate with regional changes in precipitation deduced from speleothems in nearby plateaus and in southeastern Brazilian sites.

Effect of chromium additions on the structure and physical properties of manganese-based films

The formation of metastable structures of manganese films with chromium additions obtained by the method of modernized three-electrode ion-plasma sputtering is studied. It is shown that the deposition of pure manganese leads to the formation of nanocrystalline β-Mn and MnO oxide. Heating in vacuum above 700 K leads to the film oxidation. The addition of Cr to the composition of the films prevents the formation of MnO oxide. It is shown that the activation energy of structural changes decreases with an increase in the energy of deposited atoms for pure manganese and MnCr films. Magnetization hysteresis is observed only in freshly sprayed Mn and MnCr films.

High room-temperature TCR and MR of La1-xSrxMnO3 thin films for advanced uncooled infrared bolometers and magnetic sensors

Perovskite manganese films had promising applications in the field of photoelectronic materials and devices. However, the utilization of manganese films remained severely challenging due to high fabrication cost and inferior electrical and magnetic properties. Herein, La1-xSrxMnO3 (LSMO) thin films were fabricated on La0.3Sr0.7Al0.65Ta0.35O3 (LSATO) substrates using a facile sol–gel spin-coating technique. All the LSMO films displayed (001)-orientation with orthorhombic structure. The LSMO films exhibited high temperature coefficient of resistivity (TCR) and magnetoresistance (MR) values at room-temperature. The maximum TCR value was 10.4 % K−1 (301.2 K, for x = 0.175). This result can be attributed to high carrier concentration and mobility of optimal × content LSMO films with low film-substrate lattice mismatch (-0.4%), leading to low resistivity, and thus, increased TCR value. The maximum MR value reached 42.85% (290.95 K, for x = 0.150). The LSMO films with high room-temperature TCR and MR values are potential materials for advanced uncooled infrared bolometers and magnetic sensors.

Studying the surface morphology, linear and nonlinear optical properties of manganese (III) phthalocyanine chloride/FTO films

Scientific review of laser protective materials is currently primarily focused on improving linear transmittance and developing the optical limiting ability. Due to its unique large π electronic conjugated structure, phthalocyanine has become a successful optical limiting material. Thin films of manganese (III) phthalocyanine chloride (MnPcCl) were formed on FTO substrates using traditional thermal deposition techniques. The X-ray diffraction demonstrated that there is an amorphous structure for MnPcCl films. AFM's surface morphology shows that the MnPcCl film is homogeneous and formed by spherical and elliptical nanoparticles. The thickness dependences of both linear and nonlinear optical properties of MnPcCl films were also investigated via UV–Vis-IR measurements. The absorption coefficient examination indicated that the films were distinguished by an indirect transition with two energy gaps. The power of the He–Ne (633 nm) and green (533 nm) lasers were used to estimate optical limiting behavior. The MnPcCl film deposited on the FTO revealed a high optical laser limitation that could be acceptable for different nonlinear optical devices, like laser filters.

Studies structure, surface morphology, linear and nonlinear optical properties of nanocrystalline thin films of manganese (III) phthalocyanine chloride for photodetectors application

Manganese (III) Phthalocyanine Chloride (MnClPc) thin films were deposited over glass substrates through the thermal evaporation technique. The structural characteristics of MnClPc films at various thicknesses have been studied using X-ray diffraction (XRD), which revealed an amorphous structure. The atomic force microscope (AFM) investigates the surface morphology of MnClPc thin films and demonstrates that films have nanostructure with a size of 58 nm for thickness 55 nm and slightly increased with increasing film thickness. Spectrophotometer analyses of MnClPc thin films obtained over the wavelength range of 300−2500 nm were used to determine the linear and nonlinear optical parameters. Results indicate that the optical energy gap of MnClPc films was slightly changed due to thickness. The parameters of the optical dispersion were considered using a single-oscillator model. Also, the nonlinear refractive index and susceptibility were determined by the concepts of linear refractive index dispersion. The optical limiting characteristics by using two different types of laser showed a considerable reduction in the laser output power by increasing the film thickness. This intensive result for MnClPc will probably implement in an industrial approach in the field of photodetectors and optoelectronic devices.

Effect of nickel and manganese doping on the structure, morphology and the electrochemical performance of the silicon-carbon films

The effectiveness of “pure” silicon-carbon films and the films doped with manganese and nickel as electrode materials for supercapacitors has been investigated. The films have been obtained through the electrochemical deposition from the ethanol and hexamethyldisilazane solution with metal salts addition onto the copper foil. The Raman spectroscopy showed that the silicon-carbon films are complex heterogeneous objects. Electrodes based on the manganese and nickel-doped silicon-carbon films demonstrated the larger specific capacitance compared to “pure” silicon-carbon films (414 F/g and 90 F/g at 30 A/g, respectively). The equivalent serial resistance evaluated through the impedance spectrometry is about 0.5 Ω and 0.6 Ω for the “pure” silicon-carbon film and metal-doped films, respectively.

Effect of SeO2 on the morphology of electrodeposited manganese

Most studies of the electrodeposition of manganese have focused on finding the best operation conditions to obtain good recovery efficiencies. However, few studies have focused on how these variables affect the final deposition product, the formation of initial nuclei, and crystal growth. This work studies the effect of SeO2 (0.14, 0.27, 0.54, and 0.81 mM) on the electrodeposition of manganese, the growth of the deposition product, and the microstructure of the crystals at different electrodeposition times. The catholyte was prepared by dissolving MnSO4·H2O (0.27 M) at a pH of 3.7 and (NH4)2SO4 (0.9 M), and the anolyte was prepared with a solution of 0.5 M sulfuric acid. A stainless steel 316 plate was used as the cathode, and a Pb–Ag alloy plate was used as the anode (both with an area of 57 cm2). The laboratory cell (500 mL) was partitioned with an anion-exchange membrane to prevent the transfer of ions between the compartments. Low electrodeposition efficiencies were found when using a SeO2 concentration of less than 0.27 mM due to a high rate of hydrogen evolution and dissolution of the deposited manganese film, forming a blackish deposit (MnO2). Above this concentration of SeO2, the deposits had a compact, well-defined crystalline structure and larger grain size. The availability of selenium during the initial stage of electrocrystallization allows for the formation of the first nuclei of manganese, promoting their growth.

Thickness- and substrate-dependent magnetotransport properties of lanthanum–strontium manganite films with overstoichiometric manganese content

Electrical and magnetoresistive properties of the La0.6Sr0.2Mn1.2O3±δ (LSMO) films deposited on SrTiO3 single-crystalline and Al2O3 polycrystalline substrates by magnetron sputtering have been studied. The aim of the study is to understand the effect of substrate type on the thickness-dependent evolution of magnetotransport properties of the films of lanthanum–strontium manganites with overstoichiometric manganese content. It is shown that the decrease in the LSMO film thickness below 1000 nm causes the reduction of Curie temperature (TC) and magnetoresistance value at 300 K concomitant with the increase in electrical resistivity. At the same time, the dependence of electrical and magnetoresistance parameters on the substrate structure and type becomes stronger. It is found that TC of LSMOSTO films exceeds and resistivity is smaller than the respective parameters of LSMOAO films, and the difference grows with the decrease in the film thickness. All the results show that the behavior of the doped manganite films with overstoichiometric manganese content differs from that characteristic of stoichiometric in manganese films. These observations can be attributed to the effect of manganese excess on the film growth mechanism, making it different from the manganite films of other compositions.

Study of the Photovoltage in Mn/SiO2/n-Si MOS Structure at Cryogenic Temperatures

Lateral photovoltaic effect in metal/insulator/semiconductor hybrid structures is a significant phenomenon for spintronics, as it establishes the interplay between the optical irradiation, electronic transport and spin-dependent properties of carriers. In present work we investigated photovoltaic phenomena in Mn/SiO2/n-Si MOS structure. The sample was prepared on a single-crystal n-Si (phosphorus-doped) substrate. The SiO2 layer with thickness of 1.5 nm was formed on the substrate surface by a chemical method. Manganese film with thickness of 15nm was deposited by thermal evaporation in ultrahigh vacuum in the “Angara” chamber. It was observed that at T < 45 K the values of lateral and transversal photovoltage non-monotonically depend on the temperature and such dependences show complex behavior. Features of the photovoltage dependence on temperature, in the region above 20 K are explained by the change of carriers’ mobility and the competition between carriers’ drift velocity in the electric field of the space-charge region and their diffusion rate in the transverse and lateral directions. Below 20 K, the main contribution into the photovoltage is given by hot electrons injected from surface states levels to the conduction band. A strong magnetic field influence on the photovoltage below 20 K was observed. We associate it with the Lorenz force effect on the hot electrons, although we also don’t exclude the presence of mechanisms caused by spin-dependent scattering and recombination of hot electrons at occupied donor states.

Stereometric and scaling law analysis of surface morphology of stainless steel type AISI 304 coated with Mn: a conventional and fractal evaluation

The purpose of this study is to determine the micromorphology of stainless steel type AISI 304 coated with thin films of Manganese post-annealed by the flow of nitrogen at different annealing temperatures using atomic force microscopy (AFM) and fractal/multifractal analyses. The coated samples were annealed with a nitrogen flow of 400 sccm at four different temperatures of I group, 473 K; II group, 623 K; III group, 773 K; and IV group, 923 K. AFM was used to image the 3D surface micromorphology in tapping mode, on square areas of 2 × 2 μm2. The approaches in both measurement and data analysis when using AFM analysis and surface fractal/multifractal analyses are essential for the correct interpretation of 3D surface topographic features and offer the 3D surface texture parameters and surface fractal dimension. The more irregular surface (Sq = 22.23 nm) was found in IV group, and the more regular surface (Sq = 5.86 nm) was found in II group. The result shows the effect of annealing treatment on fractal/multifractal characteristics of surfaces.

Pulsed Deposited Manganese and Vanadium Oxide Film Modified with Carbon Nanotube and Gold Nanoparticle: Chitosan and Ionic Liquid‐based Biosensor

AbstractPresent study describes the synthesis of mixed oxide films of manganese and vanadium by electrochemical pulsed deposition technique on a glassy carbon electrode (GCE) modified with multiwall carbon nanotubes (MWCNT). The film was further decorated with gold nanoparticles to enhance the reduction signal of dissolved oxygen in pH 5.17 acetate buffer solution. All of the electrochemical synthesized modified electrodes have been characterized with Scanning electron microscopy(SEM), High‐resolution transmission electron microscopy (HRTEM), X‐Ray photoelectron spectroscopy (XPS), X‐Ray diffraction (XRD) techniques. The electrode obtained (AuNPs/MnOx−VOx/CNT/GCE) was utilized as a platform for glucose biosensor where the glucose oxidase enzyme was immobilized on the composite film with the aid of chitosan and an ionic liquid. The electrochemical performance of the biosensor was investigated by cyclic voltammetry and the relative parameters have been optimized by amperometric measurements in pH 5.17 acetate buffer solution. The developed biosensor exhibited a linear range for glucose between 0.1–1.0 mM and the limit of detection was calculated as 0.02 mM.

A study of the corrosion of stainless steel 304L coated with a 190\xa0nm-thick manganese layer and annealed with nitrogen flux in a 0.4-mole solution of\xa0H2SO4\xa0at different temperatures

A method for enhancing the resistance against corrosion of stainless steel 304L coated with 190 nm-thick manganese film and annealed with nitrogen flux at constant temperature (723 K) is reported. The variable quantity in this work is the temperature of the corroding solution (293 K and 333 K). X-ray diffraction analysis was employed to investigate the crystallographical changes of the annealed samples; atomic force microscope and scanning electron microscope were used for the morphology and studying the roughness of their surfaces; polarization analysis, electrochemical impedance spectroscopy, and phase and Bode diagrams, as well as the Kramers–Kronig transformation, were employed to study the susceptibility of the samples to corrosion, at temperatures 293 K and 333 K in 0.4 M H2SO4 solutions. Our results, from all the above analyses, unanimously point to the fact that in the process of enhancing resistance to corrosion, the annealing stage is the most crucial for improving the coating and the crystal structure of the samples and that the adsorption of Mn is not sufficient for the enhancement of the surface layer. Moreover, it was observed that increasing the temperature of the solution decreases the resistance of the samples owing to an increase in the rate of corrosion.

Structurally Stable Manganese Alkoxide Films Grown by Hybrid Molecular Layer Deposition for Electrochemical Applications

AbstractHybrid molecular layer deposition (MLD) has significant potential for the creation of ultrathin electrochemically active materials, due to its ability to combine organic and inorganic species to modulate film properties. However, only a limited number of hybrid MLD processes are demonstrated with electrochemically relevant elements, such as manganese. Here, a “manganicone” manganese hybrid MLD chemistry is developed using the precursors bis(ethylcyclopentadienyl)manganese and ethylene glycol. The resulting manganese alkoxide coordination networks are shown to have many interesting properties, including the ability to seamlessly fill high aspect ratio vias and the chemical conversion into manganese carboxylate in air over several hours at room temperature. Linear, self‐saturating growth is reported. Importantly, hybrid manganicone films annealed to 480 °C in air demonstrate a greater stability to restructuring during electrochemical testing than their inorganic counterparts grown by atomic layer deposition, without reducing the activity of the reactive sites on the manganese surface. Thus, hybrid manganese films grown by MLD have significant promise for use as catalysts for the oxygen evolution reaction and as electrodes in thin film batteries.

Manganese films grown on TiO2 nanotubes by photodeposition, electrodeposition and photoelectrodeposition: preparation and photoelectrochemical properties

Manganese deposition on the surface of TiO2 nanotubes by three methods; namely, photodeposition, electrodeposition, and photoelectrodeposition, has been carried out to enhance the photoelectrochemical water-splitting efficiency of these samples for H2 production. TiO2 nanotubes have been synthesized via anodic oxidation of pure titanium. FE-SEM, XRD, Raman, and UV–visible spectroscopy have been used to characterize the morphology, structure, and optical properties of the samples prepared. Samples L-0.9 and L-0.7, prepared by photoelectrodeposition at high potential, were shown to perform better than those prepared by electrodeposition or photodeposition, based on the photoelectrochemical studies.

Investigation of nitrogen incorporation into manganese based copper diffusion barrier layers for future interconnect applications

Manganese silicate has been shown to be an effective copper diffusion barrier layer for potential complimentary metal-oxide-semiconductor integration, but issues arise with regard to subsequent thin film metal adhesion. In this work, X-ray photoelectron spectroscopy has been used to systematically investigate the effect of incorporating nitrogen within manganese-based films in terms of both surface chemistry and adhesion of subsequently deposited copper. Results show that while all manganese films are heavily oxidised, and the deposition of single phase Mn nitride thin films appears to be very difficult, manganese oxide films containing small amounts nitrogen are shown to improve the adhesion of the copper to the underlying dielectric. Furthermore, it is shown that the incorporation of nitrogen into the manganese films does not inhibit the formation of manganese silicate at the dielectric interface.

Electrocatalytic properties of manganese and cobalt polyporphine films toward oxygen reduction reaction

Novel member of polymetalloporphines, namely manganese polymetalloporphine of type I (pMnP-I) obtained by ion exchange from magnesium polyporphine of type I (pMgP-I) is reported for the first time and compared to its cobalt analogue (pCoP-I). Both polymer films have been obtained via two-step procedure: demetalation of the pMgP-I electrode film via its exposure to trifluoroacetic acid solution, resulting in formation of the metal-free polyporphine of type I (pH2P-I) followed by electrochemically induced incorporation of Co or Mn ions from the acetonitrile solution of cobalt and manganese perchlorates. A further oxidative transformation of pCoP-I, pMnP-I polymer films has led to the corresponding polyporphines of type II, pCoP-II and pMnP-II, possessing such unique features as condensed polymer structure with a very high density of active sites and high electronic conductivity within a very broad potential range including the one corresponding to the neutral (uncharged) state of the polymer matrix. Both polymers of type II also exhibit interesting electrocatalytic activity toward oxygen electroreduction in aqueous neutral (pH 6.7) and alkaline (pH 13) media which was evaluated under cyclic voltammetric and steady-state conditions. The results demonstrate that the efficiency (regardless of the electrolyte) of both polymetalloporphines is comparable to bare platinum electrode. The effect of annealing of polymer-modified electrodes on their catalytic properties has also been considered.

Studies on structural and optical properties of thermally evaporated nanocrystalline thin films of meso-Tetraphenylporphyrin manganese(III) chloride

Thin films of meso-Tetraphenylporphyrin manganese(III) chloride (MnTPPCl) were prepared by conventional thermal deposition technique, under vacuum (10−4 Pa), on glass and quartz substrates. X-ray diffraction (XRD) technique, Fourier-transform Infrared (FT-IR) technique and scanning electron microscope (SEM) were used to investigate crystalline and molecular structures, and morphology of MnTPPCl in powder form, and the as-deposited thin films. Absorption spectra of thin films were recorded in the wavelength range from 200 to 2500 nm by using Spectrophotometric measurements. Seven distinct absorptions were detected in MnTPPCl thin films in the range between 1.9 and 5 eV. The type of the optical transition and optical energy gap were estimated from the analysis of the absorption coefficient data. In the present work, dispersion parameters: oscillator energy, dispersion energy, optical dielectric constant at higher frequency, and Lattice dielectric constant were calculated as well as many other optical parameters. Nonlinear absorption coefficient spectrum of MnTPPCl thin film was obtained utilizing a linear optical parameter. The cyclic voltammetry measurements were employed to calculate HOMO-LUMO gap in the voltage range from − 2 to + 2 V.

Phase separation and local lattice distortions analysis of charge-ordered manganese films La1-xCaxMnO3-δ by Raman spectroscopy

Polycrystalline films La1-xCaxMnO3-δ (LCMO) deposited on (001) MgO substrates for three different Ca concentrations (x = 0.67, 0.75, 0.85) were studied by Raman spectroscopy, X-ray diffraction and scanning electron microscope (SEM). Images of the surface and cross-section (edge) of samples of all compositions were obtained using SEM with high (up to 1 nm) spatial resolution. It was demonstrated that changes occur in the morphology and the formation of preferential orientation films x = 0.75, 0.85 relative to the substrate. It was founded that with an increase in the quantity of calcium there occurs a decrease in parameter pseudocubic unit cell. We have investigated the temperature (80K-350K) dependence of the Raman spectra of LCMO films. We have shown that Raman response of polycrystalline films below 150K corresponds to the microscopic coexistence of isostructural phases, with crystallographic symmetry Pnma. Detailed analysis of spectra allows to detect the occurrence of several different local lattice distortions: structural phases that have weak Jahn–Teller or/and spin crossover induced structural distortions with distorted octahedra Mn3+O6 and symmetric or nearly symmetric Mn4+O6 octahedra and the octahedral tilts in charge-ordered manganese films LCMO with x = 0.67, 0.75 at low temperature. Our results confirm the coexistence of charge–ordered antiferromagnetic state and ferromagnetic metallic phases with the competition between super-exchange and double-exchange interactions.