Vibrational Bands Research Articles

Effect of modified multi-walled carbon nanotubes on mechanical properties and microscopic mechanism of lithium slag geopolymers

This study aims to examine the impact of multi-walled carbon nanotubes (MWCNTs) on the mechanical properties and micro-mechanisms of lithium slag geopolymer (LSG), a novel environmentally friendly building material. Two distinct dispersion methods, which used ultrasonication or added sodium dodecyl sulfate (SDS) dispersants, were employed to disperse both pristine and modified MWCNTs. Subsequently, these dispersed MWCNT solutions were mixed with waste lithium slag and stirred to prepare LSG. Based on the experiments, it is concluded that all of these demonstrated the most significant enhancement of LSG mechanical properties at a 0.1 % mass fraction of modified MWCNTs. In comparison with the reference LSG, the compressive and bending strengths of LSG with modified MWCNTs experienced improvements of 23.29 % and 13.76 %, respectively, after a curing period of 28 days. This was also evident from a microscopic perspective. The LSGs doped with modified MWCNTs and SDS exhibited stronger Ai-O-Si and Si-O-Si vibrational bands, as well as broader N-A-S-H and C-S-H characteristic peaks compared to the pristine LSGs. The porosity of LSG samples mixed with a mass fraction of 0.1 % MWCNTs and SDS was 37.08 % lower than that of pristine LSG. FESEM electron micrographs revealed that the modified MWCNTs functioned as fillers, bridges, and extractors of cracks in the hydration products of LSG. The aforementioned results suggest that well-dispersed modified MWCNTs have a beneficial impact on the mechanical properties and microscopic characteristics of LSG.

Impact of sol-gel synthesized α-aluminium oxide nanoparticles for the enhancement of transformer oil insulation properties

Transformers require advanced insulating materials that outperform mineral oil in terms of cooling, insulation effectiveness, eco-friendliness, and operational efficiency in extreme operational and weather conditions. As a result, emphasis has shifted to renewable and ecologically friendly materials. This change in emphasis is motivated by worries about the environment, fuel shortages, and the disposal of waste oil. Transformers have historically employed solid insulators like paper and pressboard as well as mineral or synthetic oil. However, the development of ecologically friendly insulating materials has been spurred by new environmental regulations as well as economic benefits. This research investigates the use of sol-gel synthesized aluminium oxide (Al2O3) nanoparticles to improve the insulation properties of host transformer oil. The synthesized aluminium nanoparticles were characterized with X-ray diffractometer (XRD) and found rhombohedral structure, whose chemical composition was studied by energy dispersive X-ray spectrum (EDAX). Investigation using Fourier transform infrared spectroscopy (FTIR) also revealed the production of AlOOH and hydroxyl vibrational bands at wavenumbers of 690 and 2976 cm−1, respectively. Studies using field emission scanning electron microscopy (FESEM) showed that the nanoparticles are spherical in form and have a diameter of around 38 nm. Additionally, the incorporation of α-aluminium oxide nanoparticles into the host oil showed an improvement in the breakdown voltage and suggested a possible use for better transformer oil insulation.

Hydrate–based SF6 capture and sequestration: Insights from thermodynamics, kinetics, in–situ Raman spectroscopy, and molecular dynamic simulation

Sulfur hexafluoride (SF6) is currently the most potent greenhouse gas to date due to its remarkably long atmospheric lifespan and chemical inertness. Hydrate–based technology provides an innovative solution to capture SF6 under lower pressure conditions and enables the long–term storage of SF6 gas. Herein, we conduct a fundamental study to explore the potential of capturing and sequestering SF6 gas within clathrate hydrates. The three–phase coexistence conditions were measured at the pressure ranging from 0.33 to 1.06 MPa and at ambient temperatures. A thermodynamic model was employed to predict the equilibrium conditions, using an iterative method to calculate the phase equilibrium pressure. Molecular dynamic simulation (MD) was used to observe the growth of SF6 hydrate at the nanosecond scale. In-situ Raman spectroscopy was utilized for analyzing real-time vibrational bands of S–F and O–H in SF6 hydrate, offering crucial insights into hydrate stability and growth. Additionally, microscopic kinetic experiments were also carried out to clarify the impacts of different pressures (0.8, 1.0, and 1.2 MPa) on the nucleation time, gas consumption, and growth rate during hydrate formation in both pure water and seawater. An efficient approach is proposed for the separation of solid–liquid mixtures, fabricating hydrate pellets. The findings of this study establish a foundation for the development of hydrate–based SF6 capture and storage technology.

Jahn-Teller and pseudo-Jahn-Teller effects on the vibronic structure of the photoionized spectrum of cyanopropyne.

Nonadiabatic quantum dynamics are carried out to illustrate the photoionized spectrum of the cyanopropyne (CH3-C≡C-C≡N) as reported in recent experimental measurements [Lamarre et al., J. Mol. Spectrosc. 315, 206 (2015)]. A detailed electronic structure calculation is performed to analyze the topographical details of the first five ionized states, of which three are degenerate states (X̃2E, B̃2E, and C̃2E) and two are non-degenerate states (Ã2A1 and D̃2A1). The degenerate E states of the C3V symmetry molecule are prone to Jahn-Teller (JT) instability, and in addition, symmetry allowed A1 - E vibronic coupling, i.e., pseudo-Jahn-Teller (PJT), effects are expected to have a significant impact in the detailed vibronic structure of these electronic states. The JT splittings of X̃2E and B̃2E degenerate states are small, whereas it is quite large at three high frequencies in the C̃2E electronic states. The large energy separation of X̃2E from the other states and the non-zero PJT coupling of the B̃2E state with the close-lying Ã2A1 state indicate the uncoupled nature of the X̃, Ã, and B̃ vibronic bands of C4H3N. The intersection minima of B̃ and C̃ states with the D̃ state nearly coincide with the energetic minimum of D̃ state. Therefore, the PJT couplings among these states will lead to a strong vibronic interaction to shape the respective band structure. To completely understand the JT and PJT interactions in the photoionized spectrum of C4H3N, the vibronic coupling model Hamiltonian was constructed to perform nuclear dynamics studies for these electronic states. The vibrational progressions in each vibronic band are identified and compared with the available experimental data in the literature. The impacts of JT and PJT effects in the first five ionized states of cyanopropyne are investigated and discussed in detail.

A homochiral Nickel(II) complex [Ni(P'N)2]Cl2: Synthesis, characterization, crystal structure, luminescence, DFT and Hirshfeld surface studies

A new complex ([Ni(P'N)2]Cl2) is synthesized from an anhydrous NiCl2 and a bidentate P'N (S,S)-NH2CHPhCHPhPPh2) ligand with an enantiopure ethylene backbone. The solubility of the complex in methanol aids its crystallization by slow evaporation. A single crystal X-ray diffraction study of the complex reveals a distorted square planar geometry with the phosphinyl groups coordinated in a cis(P,P) configuration. This imposes steric effects that influence the crystal packing of the complex in an orthorhombic unit cell. The complex possesses characteristic metal to ligand charge transfer (MLCT) transition in the UV region with a peak absorption at 294 nm corresponding to 4.22 eV, which correlates with 4.24 eV derived from the DFT calculation of the energy band gap between the highest molecular orbital (HOMO:7.39 eV) and lowest unoccupied molecular orbital (LUMO:3.15 eV) of the complex. With an excitation wavelength of 415 nm (3.00 eV), the complex emits photons with wavelength 488 nm (2.54 eV) in the blue region of the visible spectrum. The circular dichroism spectrum has multiple peaks in the UV region mainly associated with transitions within the chiral array of phenyl groups. The bond lengths, bond angles, and vibrational bands obtained by simulation of the optimized structure of the complex provide analytical details that strongly correlate with the experimental data with adjusted R2 of 0.9826 (bond lengths), 0.9911 (bond angles) and 0.9983 (vibrational bands). The Hirshfeld surface analysis shows that H…H and C…H interactions between phenyl rings of the cations contribute significantly to the crystal packing of the complex.

Vibronic coupling in the energetically six lowest electronic states of oxirane radical cation.

Multi-dimensional quantum mechanical simulations are carried out to understand the multi-state and multi-mode vibronic interactions in the first six low-lying viz., X̃2B1, Ã2A1, B̃2B2, C̃2A2, D̃2A1, and Ẽ2B1 electronic states of c-C2H4O·+. Vibronic coupling theory is applied to study interactions among electronic states using symmetry selection rules. A model 6 × 6 diabatic electronic Hamiltonian is constructed. The parameters of the diabatic Hamiltonian are estimated by performing extensive abinitio electronic structure calculations, using the EOM-IP-CCSD method. The nuclear dynamics calculations are performed with both time-independent and time-dependent quantum mechanical methods. The calculated vibronic structures of six electronic states are found to be in excellent agreement with the available experimental findings. Progressions found in the theoretical spectrum are assigned in terms of vibrational modes. It is found that extremely strong vibronic interactions among the X̃2B1-Ã2A1, B̃2B2-C̃2A2, and D̃2A1-Ẽ2B1 electronic states results into highly overlapping vibronic bands due to multiple multi-state conical intersections. The impact of associated nonadiabatic effects on the vibronic structure and dynamics of the mentioned electronic states is examined at length. Interesting comparison is made with the results obtained for the isomeric acetaldehyde radical cation.

Vibration annoyance due to turbulences in an airplane : subjective and physiological assessments

Turbulence phenomena in an aircraft create important vibrations, at frequencies of between 0.5 and 10 Hz. An experimental design was used to assess the influence of different signal parameters (frequency band, vertical and lateral vibration levels), and the task the participant in which the participant was involved (resting, watching a movie on a tablet computer, working by typing and using the trackpad of a computer). Thirty-three participants were subjected to around twenty signals, each lasting 45 s, using a multi-directional excitation device available in Airbus facilities. Physiological parameters (electrodermal activity, heart rate) were measured continuously. After each signal, the participant was asked to assess the discomfort of the situation. The results showed the influence of different signal characteristics or task assigned to the participant. As a general rule, subjective assessments correspond to physiological measurements. The experiment revealed the influences of the signals physical factors and the task performed by the participant. Finally, the ISO2631 standard seems to provide a good representation of the subjective evaluation of discomfort in the different configurations presented.

Crystal Growth, Structural Elucidation, Chemical Reactivity, Topology Exploration (ELF, LOL, AIM, RDG) and NLO Activity of 4-Cumyl Phenol Crystal Using Quantum Chemical Calculation

The main objective of the study is to analyze the structural behavior and NLO activity of 4-cumyl phenol by experimental and theoretical spectroscopic techniques. Its computational result is compared with the cumene compound. The optimized structural parameters of the title compound were computationally obtained at the B3LYP/6-31G (d, p) basis set. The fundamental modes of vibration were examined by experimental FT-IR, and FT-Raman techniques. The distribution of the vibrational bands was carried out with the help of normal coordinate analysis (NCA). The resulting harmonic wavenumbers were scaled by using NCA method. Topological analysis, such as Electron localization function (ELF), natural bond orbital analysis (NBO), reduced density gradient (RDG) and atoms in molecule (AIM) analysis, molecular electrostatic potential (MEP) have been used to evaluate the intermolecular interaction, especially the hydrogen bonds. UV-visible spectrum of the compound was recorded in the region 200–900 nm and the electronic properties and HOMO-LUMO energies were calculated by time dependent density functional theory approach.

Structural and Optical Properties of Nickel-Doped Zinc Sulfide.

In this study, undoped and Ni-doped ZnS nanoparticles were fabricated using a hydrothermal method to explore their structural, optical, and surface properties. X-ray diffraction (XRD) analysis confirmed the cubic crystal structure of ZnS, with the successful incorporation of Ni ions at various doping levels (2%, 4%, 6%, and 8%) without disrupting the overall lattice configuration. The average particle size for undoped ZnS was found to be 5.27 nm, while the Ni-doped samples exhibited sizes ranging from 5.45 nm to 5.83 nm, with the largest size observed at 6% Ni doping before a reduction at higher concentrations. Fourier-transform infrared (FTIR) spectroscopy identified characteristic Zn-S vibrational bands, with shifts indicating successful Ni incorporation into the ZnS lattice. UV-visible spectroscopy revealed a decrease in the optical band gap from 3.72 eV for undoped ZnS to 3.54 eV for 6% Ni-doped ZnS, demonstrating tunable optical properties due to Ni doping, which could enhance photocatalytic performance under visible light. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses confirmed the uniform distribution of Ni within the ZnS matrix, while X-ray photoelectron spectroscopy (XPS) provided further confirmation of the chemical states of the elements. Ni doping of ZnS nanoparticles alters the surface area and pore structure, optimizing the material's textural properties for enhanced performance. These findings suggest that Ni-doped ZnS nanoparticles offer promising potential for applications in photocatalysis, optoelectronics, and other fields requiring specific band gap tuning and particle size control.

Acetic acid-benzaldehyde solutions: FTIR studies, DFT, isosurface, NBO and QTAIM analyses

Fourier Transform Infrared (FTIR) spectra of pure Acetic acid (AcOH), Benzaldehyde (PhCHO) and their binary solutions at various concentration have been recorded. Density functional theory (DFT) calculations using the functional B3LYP/6-311++G (d, p), isosurface, natural bond orbital analysis (NBO) and quantum theory of atoms in molecules (QTAIM) analyses have been performed on dimers of AcOH, PhCHO and their complexes in gas phase. The results of FTIR and DFT calculations have been analysed to identify the dimers present in liquid AcOH/PhCHO and the PhCHO-AcOH complexes present in the binary solutions. The liquid AcOH consists of closed nine dimers with the different interaction schemes. The frequency shift suffered by vibrational bands of AcOH or PhCHO suggest the formation of 1:1 (PhCHO:AcOH) and 1:2 complexes in the binary solutions. The 1:2 complex exist even in 1:3/3:1 binary solution and this indicates that the AcOH dimers remains stable in the diluted solutions.

IPA: Class 0 Protostars Viewed in CO Emission Using JWST

We investigate the bright CO fundamental emission in the central regions of five protostars in their primary mass assembly phase using new observations from JWST’s Near-Infrared Spectrograph and Mid-Infrared Instrument. CO line emission images and fluxes are extracted for a forest of ∼150 rovibrational transitions from two vibrational bands, v = 1−0 and v = 2−1. However, 13CO is undetected, indicating that 12CO emission is optically thin. We use H2 emission lines to correct fluxes for extinction and then construct rotation diagrams for the CO lines with the highest spectral resolution and sensitivity to estimate rotational temperatures and numbers of CO molecules. Two distinct rotational temperature components are required for v = 1 (∼600 to 1000 K and 2000 to ∼104 K), while one hotter component is required for v = 2 (≳3500 K). 13CO is depleted compared to the abundances found in the interstellar medium, indicating selective UV photodissociation of 13CO; therefore, UV radiative pumping may explain the higher rotational temperatures in v = 2. The average vibrational temperature is ∼1000 K for our sources and is similar to the lowest rotational temperature components. Using the measured rotational and vibrational temperatures to infer a total number of CO molecules, we find that the total gas masses range from lower limits of ∼1022 g for the lowest mass protostars to ∼1026 g for the highest mass protostars. Our gas mass lower limits are compatible with those in more evolved systems, which suggest the lowest rotational temperature component comes from the inner disk, scattered into our line of sight, but we also cannot exclude the contribution to the CO emission from disk winds for higher mass targets.

Construction and photothermal properties of Ag nanoparticles modified multilevel porous CuO film with ultra-wide infrared spectrum absorption

Based on lattice vibration and energy band theory, narrow bandgap inorganic semiconductor materials have become a new type of photothermal material, but it is difficult to achieve absorption for long wavelength infrared radiation to meet the application requirements of ultra-wide spectrum (2.5–20 μm) infrared detectors. From the perspective of structural optics, this paper constructed a multilevel porous CuO film with both coral-like micro-porous and flower-like nano-porous structures based on chemical bath deposition technique, and the Ag nanoparticles were uniformly embedded in the "petal" gaps of flower-like nano-porous CuO by optimizing the dosages of PVP. Benefiting from the synergistic effect of multilevel porous structure and loaded Ag nanoparticles, the Ag nanoparticles modified multilevel porous CuO (CuO@Ag-PVP 0.05) film had an average absorption of 94.17 % over the wavelength range of 2.5–20 μm. The photothermal conversion efficiency of CuO@Ag-PVP 0.05 film can reach up to 81.12 % and 86.96 % over near-infrared and far-infrared light ranges, respectively. The various material characterizations and simulations analysis showed that the multilevel porous structure containing coral-like and flower-like multi-scale pores can form two guiding modes for light, and based on the synergistic effect of the two guiding modes, the CuO film can form a strong trapping effect for light over ultra-wide spectral range, broaden its absorption range, and enhance its absorption characteristics. The loaded Ag nanoparticles contain a large number of free electrons, which can capture light energy and convert it into heat energy through local surface plasmon resonance (LSPR) effect, further enhancing the light absorption and photothermal conversion efficiency.

The A2Π–X2Σ+ Band System of YO

YO bands are conspicuous in the spectra of S stars. The laboratory spectrum of the A2Π–X2Σ+ electronic transition has been recorded with a Fourier transform spectrometer using a composite-wall hollow cathode lamp source. The A2Π–X2Σ+ transition with v′≤4 and v″ ≤ 4 has been rotationally analyzed using the modern spectral fitting program PGOPHER. Vibronic band strengths were calculated using an ab initio transition dipole moment function. A line list for the A2Π–X2Σ+ transition is provided and can be utilized in the modeling of S stars.

Effect of Cu substitution on morphological optical and electrochemical properties of Co3O4 nanoparticles by co-precipitation method

In this present study, pure Co3O4 and Cu-substituted Co3O4 nanoparticles (NPs) were prepared by a simple co-precipitation method and their structural, morphological, optical, and electrochemical aspects were assessed. X-ray diffraction (XRD) analysis indicated that the synthesized samples had a cubic structure with the formation of a secondary phase (CuO) at a higher Cu concentration. The average crystallite was decreased with increasing Cu content. Fourier transform infra-red (FT-IR) analysis revealed that the presence of vibrational bands in Cu-substituted Co3O4 NPs. The morphological study of the pure Co3O4 and Cu-substituted Co3O4 NPs revealed that the hexagonal structure with porous nature confirmed by Field emission scanning electron microscopy (FESEM). High resolution transmission electron microscope (HR-TEM) analysis with spotty diffraction rings showed that pure Co3O4 and Cu-substituted Co3O4 NPs were polycrystalline in nature. The optical properties of synthesized samples exhibited strong absorption edges, and bandgap values were found to be increased from 3.24 to 3.75 eV. Cyclic voltammetry (CV) was employed to investigate the electrochemical properties of the synthesized materials. The CV curves exhibited pseudocapacitive behavior, and the 2 % Cu-Co3O4 electrode had a high higher specific capacitance value than the pure Co3O4 electrode.

Effect of TiO2 nanoparticles on the assembly of a copolymer-clay dispersion

Nanocomposites based on copolymer and clay minerals are attracting increasing attention as they are appropriate for extensive applications. In this work, we present results from an experimental study on the effects of TiO2 nanoparticles on a pluronic-F127/laponite water solution in the sol state. Differential Scanning Calorimetry (DSC), Dynamic Light Scattering (DLS) and Fourier Transform Infrared Attenuated Total Reflection Spectroscopy (FTIR-ATR) were used to characterize the systems. By DSC and DLS measurements the occurrence of micellization was first investigated. The temperature induced self-assembly was then studied by DLS identifying three relaxations associated to differently sized diffusing structures. The correlation between dynamics and bonding structure was thoroughly investigated by analyzing some specific infrared vibrational bands. In particular, the study of the characteristic absorption band of the ether groups in the dry state allowed to evaluate the amorphous/crystalline component evidencing the presence of more extended conformations in presence of the higher TiO2. Finally, the analysis of the bending mode for the residual water provided valuable insight about structural OH groups enabling a distinction between different types of water molecules associated to the copolymer/nanoparticle systems.

Optimization of structural, optical, dielectric and magnetic properties of Gd3+ substituted Mg-Mn mixed spinel ferrite ceramics

Manganese magnesium ferrite (Mg0.5Mn0.5Fe2O4) and Gd doped Mg0.5Mn0.5Fe2O4 (Mg0.5Mn0.5Fe2-xGdxO4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) were synthesized using the solid-state method. The structural study was performed using the powder X-ray diffraction (XRD) technique. The XRD plot confirms the presence of a spinel cubic structure for pure MgMn ferrite and the existence of a secondary GdFeO3 phase in addition to the cubic spinel phase for Gd-doped MgMn ferrite. The average crystallite size estimated from the Williamson-Hall plot decreases from 42.75 nm to 18.97 nm with the increase in Gd content. The microstructural study confirms the clear grains with well-defined grain boundaries. The Fourier Transform Infrared (FTIR) spectra of the samples show the vibrational bands at 3440 cm−1, 1636 cm−1, 1385 cm−1, 1100 cm−1, and 560 cm−1 assigned to tetrahedral and octahedral sites. The improvement in dielectric property has been observed for Gd-doped samples. The saturation magnetization and remnant magnetization decrease from 0.7 to 0.3 emu and 0.035 to 0.0273 emu respectively. The coercivity increases from 31 to 75 Oe with the increase in Gd content. The fabricated spinel ferrites have significant electrical and magnetic properties which may be promising candidates for microwave devices.

Extending the functional form of the methane PES in redundant coordinates for highly excited vibrational energy levels calculation

Potential energy surfaces (PES) of methanewhich are constructed using ten symmetrised combinations of four bond length and six interbond angles are referred to as (10S) PESs At high energy ranges, it was found that (10S) PESs permitted improving by factor of five the fit quality of ab initio electronic energies of methane versus standard nine symmetric coordinates (9S) PES representations both in internal, orthogonal or normal-mode coordinates. We extend predictions of vibrational band origins to spectral range above 10000 cm−1 to help future analyses of experimental spectra. Accuracy at high energies is increased without notable deterioration at low-E levels (rms deviation of 0.26 cm−1). Based on a comparison between various variants of (10S) PESs we expect that new theoretical band origins should have accuracy not worse than 1–3 cm−1 up to 13400 cm−1.

Growth of dendritic CuS nanostructures for photoacoustic image guided Chemo-Photothermal therapy

Herein, we report a unique method for design and development of carboxyl enriched dendritic CuS nanostructures (CuS NSs) for photoacoustic image guided chemo-photothermal therapy. The dendritic network was grown on the surface of CuS nanoparticles via layer-by-layer assembly of amino acid. XRD and TEM studies established the formation of crystalline well-spherical nanosized hexagonal covellite (CuS) phase. The successful growth of dendritic structure was apparent from the rise in surface charge, hydrodynamic diameter and characteristic vibrational band intensity of peptide bonds. The developed different generations of dendritic CuS NSs (D0-CuS NSs, D1-CuS NSs, D2-CuS NSs and D3-CuS NSs) displayed wide-ranging absorption band in near infrared (NIR) zone and exhibited good photothermal heating efficacy upon irradiation of 980 nm laser light. From in to vitro cellular studies, it has been found that the NIR irradiation effectively enhanced the photothermal toxicity of D3-CuS NSs towards cancer cells. Moreover, these negatively charged water-dispersible D3-CuS NSs were conjugated with positively charged anticancer drug, doxorubicin hydrochloride (DOX) through electrostatic interaction. The DOX loaded D3-CuS NSs (DOX@D3-CuS NSs) revealed pH dependent drug release behaviour and their considerable uptake in breast cancer cells (MCF-7). Further, DOX@D3-CuS NSs exhibited a much higher toxicity towards cancer cells upon NIR light over individual counterparts suggesting their strong ability for chemo-photothermal therapy. Moreover, these biocompatible CuS NSs have shown excellent concentration dependent photoacoustic properties at pulse laser excitation (850 nm) and thus, they can be found potential application in chemo-photothermal therapy.

Structural, spectral, dielectric, and magnetic properties of Gd3+ substituted Y-type Barium hexaferrites

Co-precipitation method is used to prepare Mn2Ba2GdxFe12-xO22 (0.00, 0.05, 0.10, 0.15, 0.20, and 0.25) Y-type hexaferrites. X-ray diffraction patterns reviled that prepared samples have single phase. The lattice parameters of ‘a’ and ‘c’ increases from 5.87 Å to 5.89 Å and 43.50 Å to 43.68 Å with the incorporation of Gd3+ (Gadolinium), respectively. Samples crystallite sizes were in the 88.8–201 nm range. The spectrum of FTIR explains Fe-O vibrational bands, which signifies the formation of Y-type hexaferrites. The maximum quality factor ‘Q’ value is obtained at 2 GHz. The maximum Q value at high frequency suggests the potential uses of prepared samples for multilayered chip inductors operating at high frequencies. A reduction in the values of saturation magnetization (Ms), coercivity (Hc) as well as in remanence (Mr) were observed in 32.0–10.2 emu/g, 19.30–5.41 emu/g, and 3084.60–1071.3 Oe range respectively. The decrement in the squareness ratio was also found in the range of 0.594–0.529. The values of squareness ratios greater than 0.5 specify that the prepared materials have a sole magnetic domain. Due to the high coercivity of the prepared materials, these could be used in devices that use high frequencies and perpendicular recording mediums.

Mixed bio-based surfactant-templated mesoporous silica for supporting palladium catalyst

The study aimed on the synthesis of bio-based surfactant-templated mesoporous silica for supporting palladium catalyst using mixed bio-based templating agents namely cashew nut shell liquid (CNSL) and castor oil for pore direction purposes. The materials prepared through co-condensation of 3-aminopropyltriethoxysilane (APTS) and tetraethyl orthosilicate (TEOS) in a 1:4 M ratio using 1:1, 4:1 and 9:1 ratio of CNSL and castor oil. The resulting porous materials were utilized to support the palladium(II) chloride catalyst, resulting in a heterogeneous catalyst-a better and more environmentally friendly catalyst than a homogeneous one. Different instruments were used to characterize the prepared materials such as nitrogen porosimeter, Powder X-ray Diffraction, Diffuse Reflectance Infrared Fourier Transform Spectroscopy and Inductively coupled plasma optical emission spectroscopy. Physisorption studies of the prepared materials indicated that the largest pore diameter of 43.84 nm could be obtained by using a 1:1 M ratio of CNSL and castor oil. On the other hand, the largest surface area of 209 m2/g was obtained from a 9:1 whereas the largest pore volume was 1.55 cm3/g from a 4:1. Diffuse Reflectance Infrared Fourier Transform Spectroscopy analysis confirmed the presence of N-H group, the bending vibration bands at around 1640 and 1543 cm−1 indicating that the reaction of organoaminesilanes and tetraethyl orthosilicate had occurred. The palladium content of the supported catalyst was determined by ICP-OES which confirmed the attachment of palladium to the synthesized materials. The highest palladium loading was obtained from the adsorbent prepared by using 1:1 ratio of surfactants mixture which gave the adsorption value of 2.16 mmol/g. Powder X-ray Diffraction indicated that the synthesized organosilica materials are amorphous with improved crystallinity upon attachment of palladium catalyst. The incorporation of palladium in the synthesized materials using the mixed bio-based surfactant was successful.