Energy Dispersive X-ray Spectra Research Articles

Effect of Nitrocarburizing and Post-oxidation Processes on the Microstructure and Surface Properties of AISI 4140 Steel

AISI 4140 çeliği, orta karbonlu düşük alaşımlı çelikler sınıfında yer almakta olup, yüksek sertleşebilirliğe sahip olması ve nispeten ekonomik bir çelik olması nedeniyle endüstride yaygın olarak kullanılmaktadır. AISI 4140 çeliği aynı zamanda nitrürlebilen çelikler arasında yer almaktadır. Nitrürleme işlemiyle, yüzeyde elde edilen sert nitrür tabakası sayesinde sadece aşınmaya dirençli bir yüzey değil aynı zamanda yorulma dayanımında da artış sağlanmaktadır. Bu çalışmada, düşük basınçlı gaz nitrokarbürleme işlemi ve farklı sürelerde son oksidasyon işlemi uygulanmış AISI 4140 çeliğinin mikroyapısal ve yüzey özellikleri araştırılmıştır. Bu amaçla, AISI 4140 çelik numuneler, 850 °C'de 60 dk östenitlenmiş 60 °C’de yağda soğutulmuştur. Soğutma sonrası numuneler 630 °C’de 60 dk temperlenmiştir. Gaz nitrokarbürleme işlem basamakları; 350 °C’de 45 dk ön oksidasyon, 550 °C’de 90 dk nitrürleme ve 550°C’de 480 dk nitrokarbürleme uygulanmış ve ardından numuneler 45-180 dakika aralığında su buharı kullanılarak son oksidasyon işlemine tabi tutulmuştur. Mikroyapısal karakterizasyon çalışmaları optik mikroskop, tarama elektron mikroskobu (SEM), enerji dağılımlı X ışını spektrum analizi (EDX), X ışını kırınımı (XRD) analizi, mikrosertlik ve yüzey pürüzlülüğü ölçümleriyle gerçekleştirildi. X ışını analiz sonuçlarından, numunelerin yüzey katmanının demir nitrür, ɛ-Fe2-3N ve ɣ’-Fe4N fazlarını ve demir oksit (Fe3O4) içerdiği tespit edilmiştir. Son oksidasyon süresi arttıkça, demir oksit (Fe3O4) tabaka kalınlığını arttığı belirlendi. Nitrokarbürlenmiş ve son oksidasyon işlemi uygulanmış AISI 4140 çelik numuneler içerisinde, en iyi sertlik derinliği, yüzey sertliği ve yüzey pürüzlülüğü birleşimi 150 dakikada son oksidasyon uygulanmış elde edilmiştir.

Influence of rare-earth elements (RE = Ce, Nd, Gd) on structural, ESR and Mössbauer spectroscopy studies of Ni0.5Co0.5RE0.03Fe1.97O4 synthesized by glycol-thermal method

Nanocrystalline Ni0.5Co0.5RE0.03Fe1.97O4 (RE = Ce, Nd, Gd) were synthesized by glycol-thermal method. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results confirm the formation of single-phase spinel ferrite. The crystallite sizes ranged from 6.29 nm to 9.41 nm which was comparable to results obtained using Williamson-Hall (W–H) method. Lattice parameters were found to vary from 8.356 Å to 8.370 Å depending on an ionic radii of a substituted rare-earth elements. Large specific surface areas ranging between 120 m2/g and 160 m2/g were associated with smaller crystallite sizes. Scanning electron microscope (SEM) revealed homogeneous and clustered nanoparticles. The energy dispersive X-ray (EDS) spectra revealed the existence of nickel (Ni), cobalt (Co), iron (Fe), and oxygen (O) in an undoped sample. The additional characteristic peaks of cerium (Ce), neodymium (Nd) and gadolinium (Gd) were observed for doped samples. The electron spin resonance (ESR) results demonstrated g-values ranging between 3.10 and 3.79 which indicated strong exchange interaction between nanoparticles, type of morphology, and crystalline nature of particles. These high g-values make Ni0.5Co0.5RE0.03Fe1.97O4 (RE = Ce, Nd, Gd) materials suitable for applications in high-frequency devices. The Mössbauer spectroscopy results revealed the formation of broadened Zeeman lines and quadrupole-split lines as well as the presence of the Fe3+ ions at B sites in the samples.

Studies of structural, dielectric, electrical, and optical properties of a multi-doped novel complex perovskite (Bi1/2Na1/2)(Fe1/3Mn1/3W1/3)O3 ceramic for opto-electronic application

(Bi1/2Na1/2)(Fe1/3Mn1/3W1/3)O3 is a new complex perovskite compound synthesized by a solid-state method. A preliminary structural study using the X-ray diffraction (XRD) pattern shows the monoclinic symmetry of the material. The scanning electron microscope (SEM) micrograph shows the dense microstructure or morphology of rectangular shape grains of different dimensions. The purity and elemental composition of the compound were obtained by energy dispersive X-ray (EDX and EDS) spectrum. The analysis of frequency and temperature-dependent relative dielectric constant (εr) impedance and ac conductivity (σac) predict the presence of Maxwell-Wagner type of dielectric dispersion and thermally activated relaxation mechanism. In-depth analysis of impedance and associated factors reveals that they are substantially dependent on temperature and have a significant link with their microstructures. Similar to semiconductors, the nature of impedance spectra displays a negative temperature coefficient of resistance behavior. The electric polarization hysteresis loop shows the ferroelectric behavior and explores the possible applications. The band gap (Eg) is found to be 2.40 eV using the UV-visible spectrum, appropriate for solar and optoelectronic applications. The value of super-capacitance is 58.96 F/g, applicable for an electrode material supercapacitor application. The behavior of leakage currents has also been investigated and found that conduction has been identified as a space-charge conduction mechanism. We are very interested in designing and manufacturing novel dielectric ceramics because of the rising need for the miniaturization of electronic components and the flexibility of applications. Sensors, actuators, transducers, and capacitors are among the most prevalent applications of such types of materials.

Room temperature sensing of ammonia and formaldehyde gases through novel anisotype heterojunction of p-Co3O4/n-Gd0.1Ce0.9O2-δ as highly responsive and stable sensors

The development of the room temperature (RT) gas sensors is absolute need. Hydrothermally and sol-gel derived Co3O4 and Gd0.1Ce0.9O2-δ (GDC) were used to fabricate the novel heterostructures in the ratio of 1:1 Co3O4/GDC, 2:1 Co3O4/GDC and 1:2 Co3O4/GDC. These samples were scientifically analysed through X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), Energy dispersive X-ray (EDX) spectra, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman, UV–Vis-Diffuse reflectance spectra (DRS) and photoluminescence (PL). XRD, XPS together with FTIR and Raman spectra are the testimonial of the formation of Co3O4, GDC and their heterostructures. Interestingly, the performed gas sensing studies conclusively disclose that these sensors have adequate sensitivity to detect the tested gases at RT. Furthermore, O2− species played crucial role than O2− and O− in chemisorption and gas sensing mechanism. Additionally, 2:1 Co3O4/GDC and 1:2 Co3O4/GDC exhibited an enormous selectivity and highly responsive towards the detection of formaldehyde (CH2O) and ammonia (NH3), respectively. 2:1 Co3O4/GDC/1:2 Co3O4/GDC offered the high response (S) of 106.59/83.52 for CH2O/NH3 gas. In fact, the formation of anisotype p-n/n-p rather than isotype p-p/n-n junctions in 2:1 Co3O4/GDC and 1:2 Co3O4/GDC endowed these two heterostructures to exhibit quick response even at low ppm of selected gases. The outcome of this work might provide strategy for the design of novel sensing materials to detect multiple gases.

Influence of deposition voltage on tribological properties of W-WS2 coatings deposited by electrospark deposition

Electrospark deposition coatings were prepared with different deposition voltage on CrNi3MoVA steel substrates by using a W-WS2 sintered electrode and their tribological properties were investigated. The microhardness, roughness and tribological properties of the coatings were tested by using Vickers hardness tester, confocal laser scanning microscope and tribometer, and the morphologies, composition and phase structure were obtained by utilizing scanning electron microscopy (SEM), energy dispersive X-ray spectrum (EDS) and X-ray diffraction(XRD). The results showed that with the increase of deposition voltage, the hardness and roughness of the coatings increase. The coatings remarkably increase the tribological properties of CrNi3MoVA steel, and among the three coatings deposited at 40 V, 60 V and 80 V, the coating deposited at 60 V has the smallest friction coefficient and the best wear resistance.

Sr2Mn0.5Hf1.5O6-δ double perovskite oxides: Structural, dielectric, magnetic, optical and transport properties

Double perovskite (DP) oxides with a chemical formula of A2B′B”O6 exhibit intriguing physical properties and structural flexibilities, which are widely used as a host structure to explore the novel candidates of half-metallic ferro-/ferrimagnetic materials. In this work, we have synthesized ferromagnetic Sr2Mn0.5Hf1.5O6-δ (SMHO) DP powders via solid-state reaction method. The powders had a magnetic Curie temperature up to 600 K, saturation magnetization of 0.59 emu/g at 2 K, and magnetic coercive field of 450 Oe. The SMHO ceramics displayed a butterfly-like magnetoresistance (MR)-H curve at 2 K due to the intergranular tunneling effect, and the MR (2 K, 7 T) value was −2.8 %. Structural investigations demonstrated the SMHO powders crystallized in an orthogonal crystal structure with Pnma symmetry. SEM images displayed a spherical morphology of the SMHO powders with particle size distribution of 100–200 nm. Quantitative EDS (energy dispersive X-ray spectra) data give out the percentage of Sr, Mn, Hf and O elements presented in approximately stoichiometric proportion. XPS spectra results confirmed the existence of Sr2+, Mn4+, and Hf4+/Hfx+(x＜4) ions in the powders, and oxygen elements were presented as the lattice oxygen and adsorbed oxygen species, respectively. Resistivity of the SMHO ceramics decreased continuously as the temperature increased from 2 K to 800 K, exhibiting a semiconductor behavior. The electrical transport data were well fitted by thermal activation model, small polaron hopping model, and Mott’s variable range hopping model, respectively in different temperature regions. Optical measurements gave out an indirect bandgap of 2.12 eV for the SMHO powders. Our present work demonstrates that the SMHO oxides are attractive in high temperature spintronic devices and solar cells owing to the integration of high TC, significant negative MR and optical bandgap located in the visible light window.

Effect of 3d-transition metal ions on the structural, optical and magnetic properties of chromium-bearing barium borate glass

This article reports the effect of 3d-transition metal ions on the optical features of chromium ions bearing glass host. Interestingly, this study unveiled the charge transfer of Cr ions at high energy (at 347 nm), which is often hidden in earlier reports due to its vicinity to the glass edge, and its immersion in the lattice band of the glass host. In addition to the well-defined charge transfer at low energy (at 378 nm). In this vein, glass composition [(TM)1−(B2O3)80−(BaO)18.7−(Cr2O3)0.3], where TM is the transition metal ions in their oxide form, was prepared via the melt-quenching method at about 1100 °C. X-ray diffraction patterns confirmed the amorphous structure of the glass, and the chemical composition was examined using energy-dispersive X-ray spectra. The decrease in density (from 2.74 gcm−3 to 2.59 gcm−3) and the increase in molar volume (from 31.92 cm3mol−1 to 34.32 cm3mol−1) were demonstrated. Moreover, the refractive index is attained at an average value (1.50). The glass structure was studied using infrared spectroscopy, which elucidated an increase in N4 (33.2%–37.5 %) and an increase in NBO (15.3%-18.4 %). Bewitshingly, the charge transfer of Cr6+ ions, at high energy (347 nm), was explored. This, in turn, leads to a proper investigation of glass absorption edges that undergo a blue shift of about 1.25 eV. Adding 3d-transition metal ions affects crystal field splitting energy and interelectronic interaction within the d-orbitals of Cr ions. Finally, ESR data confirmed the Cr5+ state (with ESR signal at 1.92) and Cr3+ state (with ESR signal at 4.6, 4.07 and 2.04) of chromium ions. Such a cohesive investigation of the structure, optical and magnetic properties of 3d-transition metal ions-bearing chromium barium borate glass paved the route toward utilization of these samples in the optoelectronic realm.

Excellent antimicrobial performances of Cu(II) metal organic framework@Fe3O4 fused cubic particles

Metal-organic frameworks have been used as antibacterial agents because of their effective antibacterial properties. In this research, nanocomposites of copper (II)- benzene-1,4-dicarboxylic acid metal–organic framework with iron oxide [Cu-MOF@Fe3O4] were prepared via a simple hydrothermal route. X-ray analysis reveals the crystallinity of the structure while FTIR analysis confirms the existence of Cu-based MOFs functional group. Cu-MOF@Fe3O4 scans using Scanning Electron Microscopy (SEM) reveal irregular clusters of cubic particles fused with Fe3O4 nanoparticles. Energy Dispersive X-ray (EDX) spectrum of Cu-MOF@Fe3O4 provides the evidence of elemental composition by showing the peaks of iron, oxygen, copper and carbon. Using the minimum inhibitory concentration (MIC) and zone of inhibition assays, the antimicrobial activity of the Cu-MOF and Cu-MOF@Fe3O4 against E. coli and B. subtilis were evaluated. The antibacterial results have shown that the Cu-MOF@Fe3O4 has higher antibacterial performance against E. coli as compared with B. subtilis as compared to Cu-MOF, Fe3O4 and ligands only. On the other hand, the Cu-MOF@Fe3O4 composites exhibit excellent antifungal potential when compared to the ligand, commercial nanoparticles, Cu(NO3)2·3H2O, iron oxide, Cu-MOF. The exploration of antibacterial mechanism revealed that the Cu-MOF@Fe3O4 composite favors slow release of metal ions and prolonged biocidal effect.

Efficient Photocatalytic degradation of direct blue 15 dye using samarium doped bismuth tungstate nanosheets: A sustainable approach towards wastewater treatment

The rare earth metal, samarium (Sm3+) doped bismuth tungstate (Bi2WO6) nanoparticles were prepared by a one-pot hydrothermal method. The powder X-ray diffraction (XRD) analysis confirmed the formation of Bi2WO6 with an orthorhombic crystal structure. The crystallite size of Bi2WO6 decreased from 20.73 to 9.25 nm as the Sm substitution in the W lattice increased. The vibrational modes of W–O, Bi–O, and Sm–O were identified in the range of 500–900 cm−1. The optical bandgap of Sm3+ doped Bi2WO6 nanoparticles increased from 2.86 to 2.95 eV with higher Sm doping levels. The surface morphology revealed the formation of flower-like sheets in the Sm3+ doped bismuth tungstate. The energy dispersive X-ray (EDX) spectrum of Sm3+ doped Bi2WO6 nanoparticles confirmed the presence of Sm, Bi, W, and O without any other impurities. The small peak detected at 1082.14 eV in the survey scan of Sm3+ doped Bi2WO6 nanoparticles belonged to Sm3d. In the photocatalytic degradation of direct blue 15 (DB15) under visible light irradiation, the efficiency of the nanoparticles increased with higher Sm3+ concentration. The obtained results demonstrated that the Sm–Bi2WO6 nanosheets could provide an effective and sustainable solution for treating the wastewater containing direct blue 15 dye.

Ecological fabrication of copper oxide nanoparticles for enhanced photocatalytic degradation of methylene blue and rhodamine B. Dye

Industrial wastewater has been an alarming issue that can have harmful effects on humans and the environment. Numerous treatment methods have been introduced to reduce toxicity, but photocatalyst treatment has been gaining interest because of its environmental behavior. This study used Grewia asiatica L. extract, which was not previously utilized to synthesize the copper oxide nanoparticles; various spectroscopic and microscopic techniques were used to characterizesynthesized nanoparticles. The UV–visible spectrophotometer spectra showed an absorbance peak at 248 nm that confirmed the synthesis of copper oxide nanoparticles. Similarly, the scanning electron microscope (SEM) and X-ray Diffraction (XRD) revealed that the synthesized nanoparticles have a size of 33.71 nm and are spherical. The energy dispersive x-ray (EDX) spectra showed the sample's elemental composition, in which copper and oxygen are present in high percentages. The Fourier infrared spectrophotometer (FTIR) spectra confirmed the fundamental biomolecules that have reduced and stabilized the copper oxide nanoparticles. The synthesized nanoparticles were developed as a catalyst under solar radiation to reduce methylene blue and rhodamine B dyes. Methylene blue was degraded 92% in 25 min with a 0.0397 min−1 rate constant. The Rhodamine B dye was degraded 98% in 50 min with a rate constant of 0.0198 min−1. Results revealed that Grewia asiatica L. mediated copper oxide nanoparticles can be used as a wastewater treatment catalystto reduce toxic dyes.

An insight into Judd-Ofelt analysis and non-contact optical thermometry of LiCa2Mg2V3O12: Dy3+ phosphors for multifunctional applications

A series of Dy3+ doped LiCa2Mg2V3O12 phosphors have been synthesized by solid state method. The phase composition of the phosphor has been analyzed by X-ray powder diffraction and confirms a cubic phase with Ia-3d space group. The scanning electron microscope images of LiCa2Mg2V3O12:xDy3+ phosphor reveals the surface morphology and is further investigated by its energy dispersive X-ray spectrum. The elemental mapping analysis displays the uniform composition of the elements present in the phosphor. The band gap energy of the phosphors has been determined from the diffuse reflectance spectra. The Judd-Ofelt intensity parameters are determined from the absorption spectra and follows the trend Ω2 > Ω6 > Ω4. The photoluminescence spectra of phosphors excited at 338 nm have intense emission at 494 and 576 nm corresponding to 4F9/2→6H15/2 and 4F9/2→6H13/2 transition and is ascribed to the magnetic and electric dipole allowed transition respectively. The radiative parameters for the optimum dopant concentration x = 0.08 has been calculated. Temperature dependent PL spectra of phosphor displays the diverse thermal response of VO43− group and Dy3+ ion and this can be utilized for the development of thermosensor based on fluorescence intensity ratio (FIR). The phosphor have maximum absloute and relative sensitivity values of 0.0063 K−1 and 0.41% K−1 in the temperature range of 80–400 K. The optical properties of the phosphor suggest that it find applications in the fields of solid-state lighting, temperature sensing, optoelectronic devices and W-LEDs.

Isomeric Molecular Forms of Pseudo-Binuclear Bismuth(III) Dithiocarbamate [Bi2{S2CN(CH2)6}6]: Preparation, Thermal Behavior, and Structural Effect of Its Solvation with DMSO, [Bi2{S2CN(CH2)6}6]⋅2(CH3)2SO

Bismuth(III) hexamethylenedithiocarbamate (HmDtc) [Bi2{S2CN(CH2)6}6] (I) and its solvated with dimethyl sulfoxide form [Bi2(S2CNHm)6]⋅2(CH3)2SO (II) have been obtained. The crystal structure of compound I shows an unusual alternation of two unsymmetrical isomeric pseudo-binuclear [Bi1/1B(HmDtc)3···Bi1A/1C(HmDtc)3] molecules, each of which involves two non-equivalent mononuclear moieties combined by secondary Bi···S bonds. The solvation of complex I leads to the structural unification of isomeric [Bi(HmDtc)3] molecules followed by their self-organization into centrosymmetric pseudo-dimers in the structure of compound II. All HmDtc ligands coordinate in S,S'-anisobidentate mode to form four isomeric (in I) or structurally unique [Bi(HmDtc)3] molecules (in II), whose distorted polyhedra can be approximated by pentagonal pyramid or octahedron. Solvating DMSO molecules are retained in the structure II by C–H···O hydrogen bonds. The analysis of energy dispersive X-ray spectra allowed one to identify the residual matter obtained by thermolysis of the complexes as Bi2S3 with admixture of Bi0.

Biomass-Derived Core-Shell Carbon Dots with Embedded Tripodal Receptors for the Selective Recognition of Mefenamic Acid in Pharmaceutical Formulations and Urine.

A tripodal amine (TPA) with -OH, N, and S donors is synthesized to functionalize a core-shell carbon dot composite (FCDs@SiO2-TPA) for sensing application. The TPA is characterized by spectroscopic and spectrometric techniques, and the composite is characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectra (EDS) techniques. The composite has the ability to recognize mefenamic acid (MFA) selectively even in the presence of other drugs like ibuprofen sodium, acetylsalicylic acid, naproxen sodium, diclofenac sodium, and ketoprofen. It can also be used for the quantification of MFA by recording the emission quenching response of the sample at λexc. = 350 nm and λems. = 460 nm (linear range = 1-8 μM and LOD = 197 nM). The density functional theory calculations and 1H NMR titration suggest quenching of the emission signal due to photoinduced electron transfer via hydrogen bonding between the probe and MFA. The composite FCDs@SiO2-TPA has been demonstrated as a reliable and cost-effective sensing probe for the detection of MFA in pharmaceutical formulations, water samples, and cow urine samples.

Investigation of structural, topological, and electrical properties of scheelite strontium molybdate for electronic devices

This article describes the synthesis (solid-state reaction) and characterizations of a scheelite strontium molybdate. The consistency of lattice parameters by N-TREOR09 and the Le-Bail Rietveld refinement method supports the tetragonal crystal system. The spectrum of the pair distribution function (PDF) depicts the orientations of atoms within a tetragonal symmetry. The Williamson-Hall plot examines the average crystallite size (86 nm) and micro-lattice strain (0.00091). The scanning electron microscopic image, energy dispersive X-ray (EDX) spectra, and elemental mapping confirm the uniform and isotropic characteristics of the synthesized material, purity and compactness, and topographic roughness according to ISO25178 standards. The investigation of dielectric, impedance, and conductivity spectra confirms the presence of Maxwell-Wagner dielectric dispersion, relaxation, and influential transport phenomena across a broad spectrum of experimental frequencies (ranging from 1 kHz to 1 MHz) and temperatures (from 25 °C to 500 °C). The observed temperature-dependent resistance characteristics validate that the prepared material is well-suited for applications involving PTC thermistors, sensors, and other related devices. The scaling properties of the modulus data provide evidence for a non-Debye relaxation mechanism. The values of the varistor constant, β1, β2, and β3, which are 1.414, 2.362, and 9.654, respectively, indicate the existence of Ohmic conduction, trap-limited space charge limited conduction (SCLC), and trap-filled SCLC mechanisms suitable for electronic devices.

Charge-transfer-driven enhanced room-temperature ferromagnetism in BiFeO3/Ag nanocomposite

We report observation of more than an order of magnitude jump in saturation magnetization in BiFeO3/Ag nanocomposite at room temperature compared to what is observed in bare BiFeO3 nanoparticles. Using transmission electron microscopy together with energy dispersive x-ray spectra (which maps the element concentration across the BiFeO3/Ag interface) and x-ray photoelectron spectroscopy, we show that both the observed specific self-assembly pattern of BiFeO3 and Ag nanoparticles and the charge transfer between Ag and O are responsible for such an enormous rise in room-temperature magnetization. The BiFeO3/Ag nanocomposites, therefore, could prove to be extremely useful for a variety of applications including biomedical.

Comparison of Al/TiO2/p-Si and Al/ZnO/p-Si photodetectors

The importance of the photodetectors has grown due to their potential in the automation system and optical communications. We fabricated Al/TiO2/p-Si and Al/ZnO/p-Si Schottky-type photodetectors. TiO2 and ZnO interlayers were grown by atomic layer deposition (ALD). The photodetection properties of these devices were studied and compared by I–V and I-t measurements for various light power densities and various wavelengths. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectra were employed to determine morphological and elemental analysis of the TiO2 and ZnO interlayers. While the SEM images showed smooth surfaces, EDX spectra approved successful synthesis of the TiO2 and ZnO interlayers with good stoichiometry. The diode parameters such as ideality factor, series resistance and barrier height values were calculated and compared in detail. The responsivity and detectivity of the fabricated photodetectors were determined as a function of illumination power density and wavelength. The responsivity values of the Al/TiO2/p-Si and Al/ZnO/p-Si photodetectors were determined as 0.02 and 0.76 A/W, respectively. Both photodetectors exhibited good performance for visible light. However, Al/ZnO/p-Si photodetector reached 173.08% external quantum efficiency (EQE) for 550 nm. According to results, Al/ZnO/p-Si photodetector exhibited better detection performance than Al/TiO2/p-Si.

Thermoluminescence study of ϒ irradiated SrSO4 nanoparticles doped with Eu for feasible application in dosimetry

SrSO4 nanoparticles doped with different concentrations of Eu were synthesised by using co-precipitation method and annealed at 500 °C, 700 °C and 900 °C respectively. The prepared SrSO4:Eu nanophosphors shows highly crystalline orthorhombic structure with crystallite size of about 30 nm as observed from the X-ray diffraction (XRD) pattern. TEM (Transmission Electron Microscopy) analysis confirms the particle size to be around 40 nm for the synthesised nanophosphors. Energy Dispersive X-ray (EDX) spectrum showed the presence of only Eu dopant without any other impurity into the SrSO4 sample. The thermoluminescence (TL) glow curve of 1 Gy of gamma ray irradiated SrSO4:Eu measured at heating rates 1 K/s has a well-defined single peak at around 468 K. The TL kinetic parameters for the synthesised nanoparticles evaluated using initial rise method, peak shape method, Booth method and deconvolution method were all in agreement and found to be activation energy (E), order of kinetics (b) and frequency factors (s).

Insights into the structural and optical features of plasma polymerized N, N, 3, 5 tetramethylaniline-2,6-diethylaniline thin films

A capacitively coupled AC (50 Hz) glow plasma has been used to produce plasma polymerized N, N, 3, 5 tetramethylaniline: 2,6-Diethylaniline composite thin films onto precleaned glass substrates at various monomer ratios. The FSEM studies revealed smooth, compact, flawless, and pinhole-free surfaces of the thin films. The energy-dispersive X-ray spectrum confirmed the existence of carbon, nitrogen, and oxygen in the composite thin films. The broadband weak absorption peaks in the FTIR spectra indicated the structural modifications in the plasma polymer caused by the reorganization of two monomer molecules during the plasma polymerization process. The thickness of the composite film increased with rising N, N, 3, 5 tetramethylaniline percentage in the composition, which had an important effect on the optical properties while keeping the polymerization parameter the same for all the deposited films. Decreasing the proportion of N, N, 3, 5 tetramethylaniline monomer results in an increase in both direct and indirect optical band-gap values, from 2.84 to 2.94 eV and 1.74–1.87 eV, respectively. While the Urbach energy values decrease from 0.649 eV to 0.556 eV. From the optical absorbance curve, it was observed that with increasing N, N, 3, 5 tetramethylaniline monomer concentration, the absorbance increased and reached a maximum at this monomer concentration of 75%. We also measured the non-linear optical parameters-steepness parameter, refractive index, extinction coefficient, and dissipation factor to understand the suitability of the composite thin films for advanced optoelectronic devices.

Photocatalytic degradation of textile dyes laden industrial wastewater using fabricated bismuth ferrite coated nickel/nickel oxide foam

Abstract Inadequate wastewater treatment infrastructure is a major environmental and public health concern worldwide. Industrial effluents containing organic pollutants such as dyes constitute a severe challenge due to their toxicity. Malachite green (MG) and methylene blue (MB) are two organic dyes that are widely used in textiles but also damage the environment. Herein, we report the fabrication of bismuth ferrite-coated nickel/nickel oxide foam (BFCNF) heterojunction photocatalyst via the dip-coating approach. The point of zero charge and the estimated surface area of BFCNF was observed to be 7.5, and 213.19 m2 g−1, respectively. Energy dispersive X-ray (EDX) spectra revealed the presence of Ni, O, Bi, and Fe elements in the BFCNF. The scanning electron microscopy (SEM) analysis revealed that BFCNF has a granular coarse surface morphology. The XRD anslysis showed that the average-crystallite size for Ni/NiO, BFO, and BFCNF was found to be 28, 1.00, and 1.00 nm, respectively. The catalyst revealed outstanding performance while degrading 97 % of MG dye at pH 6, and 98 % MB dye at pH 5, under visible light irradiation of 20 min. The chemical oxygen demand (COD) studies were also performed for both of the dyes. Notably, a negligible COD was observed for both of the dyes after 80 min. In a real industrial wastewater treatment study, the catalyst almost degraded 99 % of both dyes. Further, the catalyst revealed excellent stability during four and seven consecutive recycles tests for MB and MG dyes, respectively. The degradation process follows pseudo-first-order kinetics with correlation coefficients (regression analysis, R 2) of 0.949 and 0.974 for MG and MB, respectively. To the best of our knowledge, this is the first report on utilization of bismuth ferrite-coated nickel/nickel oxide foam based heterojunction photocatalyst. This work will trigger the development of highly efficient catalysts for efficient wastewater treatment.

Development of sustainable biomass residues for biofuels applications

A comprehensive understanding of physiochemical properties, thermal degradation behavior and chemical composition is significant for biomass residues before their thermochemical conversion for energy production. In this investigation, teff straw (TS), coffee husk (CH), corn cob (CC), and sweet sorghum stalk (SSS) residues were characterized to assess their potential applications as value-added bioenergy and chemical products. The thermal degradation behavior of CC, CH, TS and SSS samples is calculated using four different heating rates. The activation energy values ranged from 81.919 to 262.238 and 85.737–212.349 kJ mol−1 and were generated by the KAS and FWO models and aided in understanding the biomass conversion process into bio-products. The cellulose, hemicellulose, and lignin contents of CC, CH, TS, and SSS were found to be in the ranges of 31.56–41.15%, 23.9–32.02%, and 19.85–25.07%, respectively. The calorific values of the residues ranged from 17.3 to 19.7 MJ/kg, comparable to crude biomass. Scanning electron micrographs revealed agglomerated, irregular, and rough textures, with parallel lines providing nutrient and water transport pathways in all biomass samples. Energy Dispersive X-ray spectra and X-ray diffraction analysis indicated the presence of high carbonaceous material and crystalline nature. FTIR analysis identified prominent band peaks at specific wave numbers. Based on these findings, it can be concluded that these residues hold potential as energy sources for various applications, such as the textile, plastics, paints, automobile, and food additive industries.