Superficies y Vacío is an international journal that publishes researh articles in the field of Surfaces, Materials and Vacuum, in English and in Spanish, having a double blind peer review process. It is indexed at SciELO, Latindex and SJR.
Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C.
©2025 by the authors; licensee SMCTSM, Mexico. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/4.0/).
Si/Al ratio and its impact on CO2 adsorption in TiO2-Zeolite
The aim of this study was to analyze the Si/Al ratio in titanium dioxide (TiO2) and Zeolite composites (Erionite, Clinoptilolite and Mordenite) and its influence on carbon dioxide (CO2) adsorption, seeking to optimize materials for greenhouse gas capture. Composites were synthesized by the sol-gel method, varying the proportions of TiO2 and zeolites (25-75 and 75-25) as a function of weight. They were characterized using techniques such as Energy Efficiency Spectroscopy (EDS) to determine the Si/Al ratio, X-ray diffraction for crystal size, and N2 adsorption for surface area. The results showed that, in most of the composites, the Si/Al ratio decreases compared to the original zeolites, except in those based on Mordenite, which maintain high values due to their greater chemical stability. The decrease in the Si/Al ratio was correlated with an increase in the CO2 affinity, especially in the TiO2-Erionite composites, which presented the lowest Si/Al values (3.29) and higher adsorption capacity. In contrast, composites with Mordenite exhibited a lower CO2 affinity, but a higher surface area (456 m2/g). In conclusion, the Si/Al ratio is a key parameter to optimize CO2 adsorption, and the intrinsic properties of each zeolite significantly affect the composite performance. These materials have potential for applications in environmental mitigation technologies.
Copyright (c) 2025 Karin Monserrat Alvarez Gomez, María de los Angeles Velasco Hernández, Edgar Ayala Herrera, María Dolores Guevara Espinosa, Roberto Portillo Reyes https://creativecommons.org/licenses/by/4.0
Graphene derivatives-based PVA hydrogel electrolyte for supercapacitors
Hydrogel electrolytes were synthesized using polyvinyl alcohol (PVA) and various graphene derivatives, including graphene oxide (GO), exfoliated graphene (GEX), reduced graphene oxide (rGO), and selectively oxidized graphene (SOG). The effects of these graphene derivatives on the gel structure were analyzed using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and rheological measurements. Additionally, the influence of the water-to-ethylene glycol ratio on the gel properties was assessed. Incorporating graphene derivatives enhanced hydrogen bonding within the hydrogel network, depending on the oxygen functional groups and defect density of the graphene materials, leading to improved structural stability. While ethylene glycol contributes to the gel formation, adding graphene derivatives further enhances the hydrogel’s mechanical properties, maintaining a high storage modulus and preserving ionic conductivity. These findings provide valuable insights for developing supercapacitors with an optimal balance between mechanical strength and energy storage efficiency.
Copyright (c) 2025 The authors; licensee SMCTSM, Mexico. https://creativecommons.org/licenses/by/4.0
Structural properties of ceramic powders of CeO2:Eu2O3
This work aimed to synthesize and characterize CeO2:Eu2O3 ceramic powders with molar concentrations (Ce:Eu = 100:0, 98:2, 95:5, 92:8, 90:10, and 70:30). The gels were heat treated at 700 °C for 24 hours to induce crystallization of the ceramic powders. The materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), spectroscopy infrared spectroscopy (IR), Raman spectroscopy, scanning electron microscopy (SEM), photoluminescence (PL), and cathodoluminescence (CL). The results reveal that all ceramic powders presented a cubic (fluorite) structure with modifications in the lattice parameters as the Eu3+ concentrations changed. Furthermore, the Eu2O3 diffraction pattern allowed the complete identification of the crystal planes. The crystallite sizes were 64, 22, 30, 38, 40, and 50 nm for the Ce:Eu3+ ceramic powders at 100:0, 98:2, 95:5, 92:8, 90:10, and 70:30, respectively. XPS results showed a Ce3+/Ce4+ ratio of 0.27%. The IR spectrograms show the M-O bands attributable to CeO2 at 460, 560, 860, and 1200 cm-1. The results of the Raman spectra show three main bands at 260, 468, and 600 cm-1, which are associated with the F2g vibration mode of octahedral local symmetry found around the CeO2 lattice and the defect-induced mode related to the presence of oxygen vacancies due to the existence of Ce4+ ions. The particles exhibited morphological changes due to the change from the doped phase to the solid solution. The higher the concentration of Eu3+, the greater its agglomeration and size. The ceramic powders showed luminescent properties exhibiting emissions mainly by the 5D0-7D2 transition of Eu3+ and the 30 mol% sample showed higher luminescent intensity in cathodoluminescence.
Antenna effect of 2-thenoyltrifluoroacetone (TTA) on the luminescence of Y2O3 co-doped with Eu3+;Tb3+
Y2O3 gels co-doped with lanthanide ions (Ln3+) were synthesized based on the sol-gel process. Eu3+ was used in proportions of 2, 4, and 8 mol% and Tb3+ at a low and constant concentration of 0.075 mol% (Y2O3:Eu3+;Tb3+). The gels were subjected to supercritical drying (aerogel) at 73 bar and 34 °C and to thermal treatment at 800 °C to obtain crystalline materials (crystallized aerogels). Subsequently, each sample was sensitized in a novel way with 9 µmol of the compound 2-thenoyltrifluoroacetone (TTA) -- Y2O3:Eu3+;Tb3+/TTA, to provide an antenna effect in order to focus the morphological, structural-chemical, and luminescent changes assigned to the energy transitions of Eu3+. When the crystal structure by X-ray diffraction (XRD) and the morphology by scanning electron microscopy (SEM) were analyzed, no drastic changes due to functionalization were observed. However, infrared (IR) and Raman spectroscopies were performed to identify the rare-earth oxides vibrational modes, although its main function was to reveal the adhesion of TTA to materials. The excitation-emission spectra were studied to evaluate the energy transfer to the Eu3+ activator ion and the influence of both the Tb3+ sensitizer and the TTA ligand on the luminescent properties of the samples Y2O3:Eu3+;Tb3+ and Y2O3:Eu3+;Tb3+/TTA, also the quantum yield corresponding to the highest luminescence samples was calculated. Based on the results, this class of materials can have novel and useful applications when TTA functionalization is fully exploited.
Simulated ion irradiation of (Bi, Pb)-2212 superconducting thin films for the creation of magnetic vortex pinning points
Ion irradiation over superconducting thin films of (Bi, Pb)-2212 (Bi1.6Pb0.4Sr2CaCu2O8) were simulated using the software SRIM v.2013, to investigate effectiveness of this technique in creating magnetic vortices pinning points to increase the critical current density of the films. Irradiation of He, C, Si, Cu, Ag, or Au ions, with kinetic energies of 3 and 6 MeV, and angle of incidence of 0, 15, 30, 45, and 60 degrees, were simulated over films with thicknesses of 200, 500, and 1000 nm. Each atom displaced from its original position in the crystal lattice due to the fired ions was counted as a pinning point. Heavy ions such as Ag and Au were found to be the most efficient in creating pinning points. Ions with lower atomic mass like C, Si, and Cu produced a smaller number, but the sample is less likely to become amorphous due to the irradiation process. For a kinetic energy of 3 MeV, the quantity of ions trapped inside the film increases significantly, and it is only recommended for the thinnest films, or the lightest ions. A greater incidence angle increases the production of pinning points.
Structural and optical characterization of WO3 and WO3/rGO nanocomposites synthesized by a simple chemical method
The chemical structure and morphology of inorganic metal oxides have attracted increasing interest because of these parameters directly influence their sensing properties. Additionally, the incorporation of reduced graphene oxide (rGO) favors an increase in the sensitivity of these composites. Tungsten oxide (WO3) and tungsten oxide/reduced graphene oxide (rGO) nanocomposites with 3 w% (WO3/rGO) were prepared via reflux method. X-ray Diffraction (XRD), Raman Spectroscopy and Scanning Electron Microscopy (SEM) techniques were used to study the crystalline structure and morphology properties of the prepared WO3 and WO3/rGO nanocomposites. The diffraction pattern of WO3 shows the diffraction peaks of tungsten trioxide hydrate (WO3(H2O), tungstite) with orthorhombic structure; however, with the annealing at 500 °C occur a phase transformation to the monoclinic structure. The incorporation of rGO into the WO3 matrix did not modify its monoclinic chemical structure. The crystallite size of the reduced composites increases as the percentage of rGO increases. Furthermore, the optical properties of WO3/rGO nanocomposites were characterized by Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS). The band gap of WO3/rGO composites varies between 3.32 and 3.35 eV. SEM images of WO3 show structures of nanoplates with rectangular transversal section.
Self-organized gold nanoparticles on SiO2 surface nanopatterns induced by MeV ion implantation
Ion implantation at MeV energies leads to the formation of surface nano-patterns on diverse kinds of materials, such as metals, dielectrics, and semiconductors. Furthermore, under oblique irradiation, the implanted ions are preferentially deposited on the crests of such patterns. Based on previous experimental results, in this work the formation of gold nanoparticles is produced and found to be organized onto prepatterned surfaces as produced by 1.8 MeV Au ion implantation on SiO2 substrates at an impinging angle of 45°. The ion implantation was performed with an ion beam current of 400 nA for a total ion fluence between 0.2 ×1017 cm-2 and 2.0 ×1017 cm-2. After implantation, to assist gold nanoparticle nucleation, substrates were annealed at 1000 °C. The surface morphology and topography of the implanted substrates were analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. For the lowest fluences (0.4 - 0.8 ×1017 cm-2), the formation of isolated surface structures on a flat background was observed whose morphology mimics the exoskeleton of a bug. According to SEM-EDS analysis, the formation of gold nanoparticles on the exoskeleton of the bugs was observed. For intermediate fluences (0.8 - 1.4 ×1017 cm-2), a ripple background now appears and begins to surround the bugs. At the highest fluences (1.4 - 2.0 ×1017 cm-2), the surface shows only a ripple pattern. In this last case, the gold nanoparticles are formed along the crests of the surface ripples. Finally, the optical absorption of the samples (except the one corresponding to the lowest fluence) shows the presence of a localized surface plasmon resonance (LSPR) in the wavelength region of 520 - 540 nm, suggesting the presence of gold nanoparticles.
We thank the contributing authors for choosing Superficies y Vacío to communicate their research results, and quite as important, the selfless contribution of the peers who accepted to review the received manuscripts, helping to keep the high-quality of the articles that we publish. We hope for both communities to grow further in the times to come. This year, upon the suggestion of the ‘XVII International Conference on Surfaces, Materials, and Vacuum’s Organizing Committee, the Editorial Board extended a special invitation to the Conference contributors to send their results in a full manuscript to be considered for publication in Superficies y Vacío. In spite of the moderate response, we consider this has been a successful exercise, giving feedback from an editorial revision within 10 days from the Conference ending. I deeply appreciate the support from two Editorial Board colleagues, Cristo Manuel Yee Rendón and Martín Guadalupe Zapata Torres, with whom this initial process was completed satisfactorily. Nonetheless, to this day only one of thus received manuscripts has its peer review process complete. We are working to complete the review process for the remaining manuscripts under consideration within the first months of 2025. In Superficies y Vacío, we wish you all a Happy and Successful 2025! December 30th, 2024 Miguel Angel Santana-Aranda
Copyright (c) 2024 Miguel Angel Santana-Aranda https://creativecommons.org/licenses/by/4.0
Pair distribution function analysis for Pt-Pd-Co atomic mobility in nanoparticles
Through the in-situ monitoring of fuel cells in oxidation-reduction processes with ternary nanoparticles (Pt-Pd-Co), the Pair Distribution Function (PDF) is created by the Fourier transform of the high-energy X-ray diffraction pattern of the sample. Lattice deformations in nanostructures have been shown to be reflected in the oscillation of the peaks of the atomic PDF. Analyses have revealed that there is atomic mobility within the nanoparticles. Thus, in this work we study the effect on PDF of different internal variables for nanoparticles modeled based on data from a previous interdisciplinary study by a third party, the variables include temperature, vacancies and atomic species distribution. Several atomic structural models were created, and molecular dynamics simulations were applied to them using LAMMPS and the Modified Embedded Atom Method (MEAM) for the atomic interaction. The PDF’s generated from the models were compared to experimental data and the best match was identified. It is shown that a non-uniform distribution of the elements of the ternary system within the structures is the cause of the lattice strain oscillations for the nanostructures, mainly the radial distribution of Co turns out to have a greater effect on the peaks of interest in the PDF altering the general structure of the nanoparticles.
Copyright (c) 2024 The authors; licensee SMCTSM, Mexico. https://creativecommons.org/licenses/by/4.0
Photoluminescent carbon colloids prepared by laser fragmentation of carbon from waste coffee grounds
Colloidal suspensions of carbon nanostructures (CNSs) were prepared by laser fragmentation in various liquid media using heat-treated coffee grounds as carbon precursor. A study by calorimetry was done in powder of waste coffee grounds to determine the temperature of obtaining carbon. The experiments were carried out in two stages, the first one consisted in obtaining the carbon source, for which powder of waste coffee grounds was thermally treated in air. The as-obtained carbon was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy and infrared spectroscopy. In the second step the as-obtained carbon was separately dispersed in four liquid media (acetone, toluene, methanol and isopropyl alcohol) to be fragmented by using a ns-pulsed Nd:YAG laser at its 1064 nm fundamental emission. The morphological features of the carbon nanostructures were obtained by transmission electron microscopy, while the optical properties of the colloidal suspensions were characterized by UV-Vis and photoluminescence spectroscopies. Results indicate that carbon nanostructures are successfully obtained in the four liquid media after the fragmentation process. The four colloidal suspensions show photoluminescent properties, which are seen to depend on the liquid medium nature. We found that the liquid medium also influences the efficiency of the laser fragmentation.
Study of electronic and optical properties of Sm3xY3(1-x)Ba5Cu8O18 superconductor using the LAPW+lo method
This work presents a calculation of the electronic and optical properties of the family of high critical temperature superconductors (Tc > 90 K) Sm3xY3(1-x)Ba5Cu8O18 (Sm3xY3(1-x)58), para 0 < x < 1, as well as those of Y1Ba2Cu3O7 (Y123) and those of Sm1Ba2Cu3O7 (Sm123), carried out using the first principles method LAPW+lo (linearized augmented plane wave + local orbitals), within the DFT theory (density functional theory). The Density of Electronic States (DOS) and optical conductivity are calculated for four crystal structures generated by varying x (for x = 0; 1/3; 2/3; 1). The objective was determined. DOS (partial and total) and optical conductivity at low energies. In particular the effect of the f orbitals of Sm near the Fermi energy (Ef). It was found that by substituting Sm atoms for Y atoms, the total DOS is affected around Ef due to the contribution of the Sm f orbitals. When the system has two atoms of Y and one of Sm (Sm1Y258). The value of the total DOS in the Ef increases 547% with respect to the compound Y358. When the system has 2 atoms of Sm and one of Y (Sm2Y158), the value of the total DOS in the Ef increases 1043% with respect to the compound Y358. While in the case of Sm358, it increases 1432%. For Sm123 and Sm358 the optical conductivity presents a peak near the origin. While for Y358 it does not present any peak in conductivity and presents very low values near the origin. For the cases x = 1/3 and 2/3 we find that the conductivity is modified near the origin. The highest value occurs for the system containing two Sm atoms, this was at 0.14 eV.
Density of electronic states; Sm3xY3(1−x)58; f-orbitals; Optical conductivity.
Method for measuring the setting process of cement-water mixtures by electrical impedance
The setting and hardening of cement paste can be taken as the progressive hydration reaction of cement. This paper reports the findings on setting time of cement paste at early hydration by using a novel method named relative electrical impedance (REI). The novel REI method measures the relative electrical impedance between electrodes (ring shaped) embedded in the cement paste. REI measurements were conducted on cement paste samples with a water-cement ratio of 1:2 over 24 hours. REI measurements were compared with VICAT and heat latent methods for indirect validation. It was found that the proposed REI technique determined the 4 periods of the setting time process (sleeping, hydration, deceleration, and diffusion) and allowed the measurement of the sleeping period in detail. It was concluded that the novel REI method could be used as a new method to measure the setting time of cement paste in early hydration.
Optical and structural properties of Fe2O3-ZnO composite thick films obtained by ultrasonic spray pyrolysis
Fe2O3-ZnO composite gained attention due the several applications like that sensors, photocatalysis, reduction of mercury ions. Fe2O3-ZnO composite thick films were prepared by Ultrasonic Spray Pyrolysis on a glass substrate, using 0.1 M aqueous solutions of FeCl3?6H2O and ZnCl2 anhydride. To obtain different elemental concentration of Fe and Zn, we varied the volume of each aqueous solution. The XPS analysis shown that it is possible to modulate the concentration of Zn and Fe in the samples. The X-ray diffraction measurements revealed that the films were composed of different phases corresponding with common stable iron oxides (ZnFe2O4, Fe2O3) and zinc oxide (ZnO). Results from Raman spectroscopy indicate that Fe2O3 vibrational modes are accompanied with new modes due to the presence of additional phases ZnO compounds. The band gaps were evaluated with the help of UV-visible transmittance data using the Tauc model, the results shown a modulation of the band gap values (2.2 eV to 3.2 eV). Theorical transmittance curves were obtained using the effective medium theory, using the Bruggeman model, these curves showed similar behavior that the experimental transmittance curves.
Copyright (c) 2023 The authors; licensee SMCTSM, Mexico. https://creativecommons.org/licenses/by/4.0
Tailoring optical response in nanostructured bilayers: Effects of surface roughness and layer thickness on NbN/Nb and TiN/Ti
Numerical calculations were performed on NbN/Nb and TiN/Ti nanostructured bilayers. Discrete dipole approximation implemented in the DDSCAT code was utilized. In order to design a TUC (Target Unit Cell) with realistic surfaceroughness pattern, Atomic Force Microscope images of 100 ±10 nm Nb thin films were used. The optical properties of nanostructured bilayers (60-100 nm thickness with a ±10 nm surface roughness) were calculated, keeping the interface between the layers as smooth flat surfaces. For the NbN/Nb nanostructure with a thickness between 100 ±10 nm, and 70 ±10 nm, in a wavelength range between 200 and 350 nm, the reflectance and absorptance show a nearly flat spectrum with an intensity of 20% and 80%, respectively. For larger wavelengths, absorptance decays smoothly. In contrast, for the 60 ±10 nm bilayer, the absorptance decays faster. For the TiN/Ti nanostructure, at 415 nm, a relative maximum in the reflectance, and a minimum in absorptance, are observed. The critical value of the absorbed light spectra begins to shift to higher wavelengths as the thickness of the TiN layer increases. We demonstrate that adding a rough nitride layer on top of its metallized layer drastically modifies the optical response of the nanostructured bilayer, an interesting result for plasmonics and nanoelectronics applications.
Amorphous TiO2-Au thin film composites synthesized by pulsed laser deposition
TiO2 has been widely studied and synthesized by various methods due to its excellent optoelectronic properties. It is possible to modify the optical properties of TiO2 by incorporating noble metal nanoparticles in order to improve its photoresponse. In this work, TiO2-Au thin film composites were grown by pulsed laser deposition technique. Ti and Au targets were simultaneously ablated in order to produce combined plasmas under a reactive atmosphere containing oxygen at a pressure of 2×10-2 Torr. The plasmas were analyzed individually by means of a planar Langmuir probe in order to calculate their mean kinetic ion energy and plasma density. Ti plasma parameters were kept constant at 196 eV and 2.06×1013 cm-3 while the Au plasma density was varied from 2.65×1012 cm-3 to 22.4×1012 cm-3. The samples were characterized by UV-Vis spectroscopy and scanning electron microscopy. The band gap of the films was determined by means of the Tauc method, which decreased from 2.36 to 1.54 eV as the Au plasma density increased. The resultant morphology of the films shows the formation of spherical Au nanoparticles, whose average sizes increases as the Au plasma density increased, resulting in values ranging from 15 to 72 nm.
Photopyroelectric technique for the measurement of optical properties of pure liquids
Photopyroelectric technique, in the transmission configuration, was shown adequate for the measurement of the optical properties of pure liquids. The analytical scheme involves the scanning of the photopyroelectric signal as a function of the sample thickness. Optical absorption coefficients, at four wavelengths in the near infrared region (904 nm, 980 nm, 1310 nm, and 1550 nm), were measured for eight pure substances, distilled water and glycerol, among them. Strong optical absorption was obtained, particularly for pure liquids with a hydroxyl group in their molecular structure. In order to figure out about the influence of this chemical group on optical properties as function of the size of the molecule, optical absorption coefficient for a series of linear alcohols at 1550 nm was also measured.
TOF–SIMS analysis of mouse fibroblasts cells
In this paper, we have shown the results of the analysis by the SIMS method of mouse fibroblast cells (3T3-F44A2 line) grown on the silicon surface and fixed by using different chemicals. It was concluded that the standard method of dehydration and fixation of cells with the help of glutaraldehyde allows us to prepare relevant samples for analysis by the SIMS in ultrahigh vacuum. Ion images of chemical elements inside cells with a sufficiently high lateral resolution were obtained, allowing us to study, among other things, the internal structure of cells. The use of SIMS looks preferable for the analysis of cellular metabolism, cell differentiation, ischemia and other processes in cells and tissues grown using special medications and (or) reagents with an artificial isotopic composition of stable isotopes.
We are grateful to our contributor authors for choosing Superficies y Vacío to disseminate their research results, as well as the selfless contribution of the peers who accepted to review the received manuscripts, helping to keep a high-quality standard for the articles that we publish. We hope for both communities to grow further in the times to come. We are pleased to highlight the integration of some updates to our publishing process: registration of Digital Object Identifier (DOI), through CrossRef, along with automatic registration to the authors’ Open Researcher and Contributor ID (ORCID), within an Open Journal Systems (OJS) editorial platform; and to the print format of the published articles, keeping our usual author grouping by institution, and adding the standard ordered authorship list below the title. We also transitioned our review process from single- to double-blind. And have been fulfilling a self-imposed ‘1.5 weeks’ deadline for a first answer with recommendations from a member of the editorial board, which is successfully reducing the time span of our peer review process.
Copyright (c) 2022 . https://creativecommons.org/licenses/by/4.0
The role of Zn-complexing agents in the chemical bath deposition of ZnO and ZnS thin films
In order to control the deposition of Zn-related films by chemical bath deposition, the effects of Zn-complexing agent are analyzed. ZnS films were produced by chemical bath deposition technique employing sodium citrate, ethanolamine and Triethanolamine as complexing agents. The deposition conditions for ZnS (ZnO) thin films were obtained through a thermodynamic analysis, using distribution diagrams for molar fraction of Zn complexes. From species distribution diagrams of Zn-ethanolamine, Zn-Triethanolamine and Zn-citrate. It was found that for pH values between 4 and 6 the highest Zn fraction is obtained. The results highlight the importance of complexing agent morphology, while the use of ethanolamine and triethanolamine produce ZnO films due to their high reactivity; the use of sodium citrate produce ZnS films. Deposited ZnS films have a cubic structure, n-type conductivity, resistivity of 8.36×104 ??cm with a 3.75 eV bandgap.
Copyright (c) 2022 The authors; licensee SMCTSM, Mexico. https://creativecommons.org/licenses/by/4.0
Structural study of the rare earth compounds: Sm(OH)3, NdOHCO3, CeO2, and Ho2O3, prepared by Chemical Bath Deposition, and its correlation with crystal growth mechanism
We present the preliminary theoretical-experimental study of the structural properties for rare earths: hydroxide, hydroxycarbonate and Oxide; Sm(OH)3, NdOHCO3, CeO2, and Ho2O3 powders, respectively. In the experimental preparation, Chemical Bath Deposition (CBD) technique is applied at ~20 ±2 °C. In our experimental conditions, the parameters of crystal growth are: concentration of progenitor reagents, stirring, pH and temperature, remain constant. The chemical kinetics of crystal growth is systematically examined at key synthesis steps, considering the physicochemical and electrodynamic parameters: ionic radii, electron affinity, and hydration enthalpy of the rare earth (Sm3+, Nd3+, Ce3+, and Ho3+) cation. The main objective of this report is to investigate the theoretical-experimental correlation associated with the experimental conditions and the physicochemical parameters in the synthesis of hydroxide, hydrocarbonates and oxide. The crystallographic study of the powders is carried out using the X-ray Diffraction (XDR) technique. Analyzing the crystal phase, it is found that Sm(OH)3 and NdOHCO3 present hexagonal crystal phase, CeO2 and Ho2O3 are identified cubic crystal structure. The quantified grain size turns out to be: Sm(OH)3: ~1.40 - 2.03 nm, NdOHCO3: ~14.33 - 22.25 nm; CeO2: ~1.65 - 3.05 nm; and Ho2O3: ~3.72 - 6.08 nm. The Dislocation density (?) is: Sm(OH)3: ~2.47 - 5.10×1017 lines/m2; NdOHCO3: 2.01 - 4.68×1015 lines/m2; CeO2: 1.07 - 3.67×1017 lines/m2.
Relationship analysis of surface roughness measurements on coatings using AFM and fractal dimension by mesoscopic model methods
Surface coating is a method used for protection against corrosion and environmental impact for metals. In the case of solid surfaces, coatings can be achieved by radio-frequency magnetron sputtering or other corrosion-resistant substances, which may involve the deposition of one or more layers, depending on the procedure involved, modifying the morphology of the surface and surface area. This work aims to study the relationship of two surface morphological methods through roughness and fractal dimension measurements in top-surface coatings, bilayer Ti/WTiN/WTiC (named as n = 1); multilayer [Ti/WTiN/WTiC] (named as n = 40) deposited by RF-magnetron sputtering. The measurements were obtained by profilometer and image processing pixel intensity. The topography of each coating exhibited texture with impurities as domes distributed in small cluster island types. The surface roughness were 9.42 and 18.63 nm; fractal dimension measurements were 2.55 and 2.32, respectively, with a low correlation between roughness and fractal dimension. The R-squared analysis exhibited a good relationship between the fractal dimension values, tending linear regression negative. The result of factorial design 22 confirmed the performance correlation and linear regression analyses. The fractal dimension measurements by the optical method can be great potential to evaluate surface roughness complementary in applications such as laboratories and even in scale industrial. Thus the result of statistical treatment shows high accuracy in the measurements.
Effect of the neodymium doping on the magnetic and structural properties of the Sr-hexaferrite obtained by the Pechini method
In this work, neodymium (Nd3+) doped strontium hexaferrite was obtained using the sol–gel based Pechini method. The cation distribution was modified by doping with different amounts of Nd3+ ions when 0.0 ? x ? 0.4 according to the chemical expression Sr1-xNdxFe12O19 the powders were sintered at 1100 °C for 1 h. The influence of the neodymium was analyzed, and the magnetic and structural properties have been associated with the fabrication method. The crystalline phases, structure, and particle morphology of the samples were determined by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. In addition, the magnetic properties were measured at room temperature using a vibrating sample magnetometer with an applied field of up to 20 kOe. Moreover, magnetization and coercivity values are influenced by the neodymium content. The results showed that the Pechini sol-gel method allows a limited solubility of the Nd3+ ions on the hexaferrite structure.
Copyright (c) 2022 The authors; licensee SMCTSM, Mexico https://creativecommons.org/licenses/by/4.0
Mechanical properties and Keratinocytes cellular evaluation of Polycaprolactone/Collagen/Elastin Electrospun Fiber Scaffolds
Bioinspired membranes as extracellular matrices are desired for skin regeneration. Herein, we fabricate four systems of fibrillar membranes composed of polycaprolactone (PCL), aminolyzed PCL, denatured collagen type I (C), and the blend of collagen hydrolysate types I and III (bC) or elastin (E), fabricated by the electrospinning process. The superficial features by SEM and optical profilometry, mechanical properties by puncture strength assays, and biological evaluation with a human keratinocyte cell line (HaCaT) for one day of aPCL6bCE (aPCL/collagen hydrolysate type I and III/Elastin), aPCL6CE (aPCL/denaturated Col I/elastin), aPCL6bC (aPCL/collagen hydrolysate type I and III), and PCL6bCE (PCL/collagen hydrolysate type I and III/Elastin) membranes are described. The aPCL6bCE and aPCL6CE fibers resulted in better structural properties for culturing cells, while aPCL6bC and PCL6bCE membranes have shown lower viability for keratinocytes, probably due to their different chemical surface and nanotopography. The roughness of these materials varied from 4.53 to 114.4 µm, depending on their diameter values. Puncture strength results were not significantly different within 2.25–2.66 MPa. Our results suggest that aPCL6bCE and aPCL6CE fibers have potential applications in skin tissue engineering, where the synergy among aminolyzed PCL and E seems to be a prerequisite to developing such activity.
Intercalation of p-toluenesulfonic acid into Mg-Al layered double hydroxide
Layered double hydroxide represents a class of materials for selective adsorption and catalysis. In the present work, anionic p-toluenesulfonic acid (PTSA) was successfully incorporated into the interlayer domain of Mg-Al layered double hydroxide (LDH), synthesized by the co-precipitation route. Materials were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, magic angle nuclear magnetic resonance (13C MAS-NMR) spectroscopy and UV-Visible diffuse reflectance (UV-VIS/DR). All samples supported PTSA intercalation at room temperature in the basal space, the interlayer distance increased by the intercalations of the above mentioned according to the arrangement of PTSA molecules in the interlayer. The LDH-PTSA structure collapsed at 400 °C and the organic portion of those materials occurred by partial combustion, which in turn gives rise to reduced species, such as carbon and sulfide anions.
Copyright (c) 2022 Maria Elena Manríquez-Ramírez, Carmen Magdalena Reza-San Germán, Miriam Estrada-Flores https://creativecommons.org/licenses/by/4.0
Spectroscopic study of silver nanoparticles passivated with the conjugated polymer PEDOT:PSS
Silver nanoparticles AgNPs were synthesized using sodium boronhydride as reductant and poly(ethylendioxithiophene): poly(sodium estiren sulfonate) PEDOT:PSS, as stabilizer. The following synthetic parameters were varied: 1) PEDOT/PSS relative content, using three different commercial formulations; and 2) molar ratio between the silver salt and the reductant. By UV-Vis spectroscopy, the formation of the AgNPs was corroborated with the plasmonic band at ~ 400 nm, moreover changes in the PEDOT absorption were observed with the richer PSS formulations and the salt/reductant ratio was ~1, which according to Raman can be associated with a conformational change to a more benzenoid structure. In the other conditions, the spectroscopic properties are similar to those of nanoparticles prepared with only PSS. Based on the results, we consider that the AgNPs are stabilized with the PSS that is in excess, out of the conductive PEDOT:PSS domains, when the formulation contains more PSS or when low amounts of NaBH4 are used. Increasing the NaBH4 content, the AgNPs are formed also inside the PEDOT:PSS domains. The optical and electrical properties of the NPs are thus modulated depending on the preferent stabilization mechanism.
Copyright (c) 2021 The authors; licensee SMCTSM. https://creativecommons.org/licenses/by/4.0
Pd/SBA-15 catalysts in the catalytic wet air oxidation of phenol
A series of palladium catalysts (0.5, 1.5 and 3.0 wt%) were synthesized by impregnation at pore volume on a silica-based mesoporous molecular sieve (SBA-15). Materials were characterized by N2 physisorption, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (HR-TEM). The catalytic activity was evaluated in catalytic wet air oxidation (CWAO) of phenol at 160oC, 10 bar, 200 mg of catalyst and 200 mL of phenol from a 500 ppm solution. The results of the characterization show a great influence of the metallic content of Pd; the specific area decreases when introducing a higher percentage of palladium. The materials presented texture, structure and morphology according to what has been observed in literature. It was found that the size of the supported palladium oxide species formed during the calcination stage was smaller in the catalyst with lower metal content (Pd0.5/SBA-15) and this was the most active in the degradation of phenol and degraded 64% of phenol, being the most active of the catalysts.
Colorimetric characterization, texture and sanitary quality of breads added with Creole corns and Curcuma longa
The objective of this research was to characterize the color, texture and sanitary quality of bread added with creole corn and turmeric. Fourteen different breads were made using six types of corn (M1, M2, M3, M4, M5 and M6). The main findings were a) The color of the corn, nixtamalized flours and doughs had a significant difference (p < 0.05) when comparing mean values of Luminosity, a* and b* parameters. Blue and reddish corn M2 (37.01), M3 (44.06) and M6 (41.07) and, yellow and yellow orange M1 (21.26), M4 (15.92) and M5 (26.01) presented the lowest values in L* and highest in b*, respectively. The smallest difference in color ?E found in the transformation process from corn to flour and dough, was for yellow corn. b) In corn bread, significant differences in variable a* were found when comparing the same type of bread for three consecutive days, in breads BM1, BM5 and BM6, with a decrease of 7.5, 2.6 and 16.9%, with respect to the first day. c) The sanitary quality of wheat bread improves with the addition of nixtamalized corn and turmeric. The blue and red corn (M2, M3 and M6) showed the lowest number of fungal colonies in the breads with corn additives. d) The hardness of the bread made with creole corn and turmeric did not show differences during three consecutive days, benefiting its conservation. The yellow corn and turmeric bread BM1-C showed increases in the hardness on days 2 and 3, and the yellow corn and turmeric bread BM1-C showed increases in the hardness on days 2 and 3.
Breads added with Creole corn and Curcuma longa
Importance of liquid phase epitaxy on achieving near-lattice-matched growth of In0.145Ga0.855As0.132Sb0.868 layers on GaSb(100) substrates
We report the growth of In0.145Ga0.855As0.132Sb0.868 layers on GaSb(100) substrates by the liquid phase epitaxy (LPE) technique using the ramp-cooling method. We achieved a near-lattice-matched epitaxial growth with a lattice mismatch of between the quaternary layer and GaSb(100) substrate due to optimal growth parameters. Aberration-corrected scanning transmission electron microscope (AC-STEM) confirmed the high crystalline quality of the quaternary layer and the low lattice mismatch in the heterostructure, without the presence of linear or planar defects. Also, the Secondary Ion Mass Spectrometry (SIMS) technique evidenced a uniform distribution of the atomic elements along the quaternary layer and an abrupt interface between the In0.145Ga0.855As0.132Sb0.868 layer and the GaSb substrate. Plasmon-phonon interactions were observed by Raman spectroscopy indicating that the crystalline quality increases at greater depth in the sample with respect to the surface. The quaternary layer presented a uniform and flat morphology, and luminescence emission attributed to the recombination of bound exciton states at 641 meV. The structural, chemical, and optical properties of the In0.145Ga0.855As0.132Sb0.868 layer demonstrated that it could be auspicious material for infrared range optoelectronic applications. Likewise, the LPE technique successfully shows that it should be used to grow near-lattice-matched heterostructures.
In memoriam. Orlando Zelaya-Angel’s contributions in Superficies y Vacío
Professor Orlando Zelaya Angel was an outstanding member of the research community on Solid State Physics. He served as President to the Sociedad Mexicana de Ciencia de Superficies y Vacío (SMCSyV; currently Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales – SMCTSM), for the period 1995-1996. Professor Zelaya formed many researchers in Mexico, who continue developing research, either in Mexico, in their countries of origin, or abroad. Throughout the evolution of Superficies y Vacío, Professor Zelaya, contributed with sixteen articles on subjects ranging from thin films for optoelectronic applications, through hard coatings and studies on the process for production of Tortillas; covering most of his research areas of interest. Here is a subject-chronological compilation of the abstracts to his articles in Superficies y Vacío, after a year of his departure.
Is sulfur the responsible for color of yellow Chiapas Amber?
Amber is a fossilized natural resin found in specific areas of the world; its geographical origin is associated to a characteristic color. Amber all over the world share basic characteristics due to a common polymeric matrix; however, its color is associated to the environment where it was formed. In this work, based on a compositional analysis, it is proposed that yellow color of Mexican amber is originated from the sulfur physical and chemical interaction within its polymeric matrix. The effect of sulfur present in yellow Mexican amber is studied by employing X-ray photoelectron and UV-Vis spectroscopies. Results show that sulfur is incorporated inside the polymer matrix with two different chemical environments; one related with sulfur-carbon bonds and the other with sulfur-sulfur bonds. The optical transmission spectrum simulated considering amber as a composite material reproduce the scattering contribution observed experimentally.
Copyright (c) 2021 Geraldine Vázquez Bautista, M. Zapata Torres, F. Chalé-Lara , M. Meléndez Lira, E. Hernández Rodriguez, E Valaguez Velazquez https://creativecommons.org/licenses/by/4.0