https://superficiesyvacio.smctsm.org.mx/index.php/SyV <p>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.</p> Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. en-US Superficies y Vacío 1665-3521 <p>©2022 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 (<a href="http://creativecommons.org/licenses/by/4.0/" target="_blank" rel="noopener">http://creativecommons.org/licenses/by/4.0/</a>). </p> https://superficiesyvacio.smctsm.org.mx/index.php/SyV/article/view/2024_syv37_1-240101 <p>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.</p> Eduardo Morales Sánchez Jorge Pineda Piñón Alejandro Manzano Ramírez José Mauricio López-Romero Marcela Gaytán Martinez Guadalupe Omar Sánchez Vega Copyright (c) 2024 The authors; licensee SMCTSM, Mexico. https://creativecommons.org/licenses/by/4.0 2024-02-07 2024-02-07 37 240101 240101 10.47566/2024_syv37_1-240101 https://superficiesyvacio.smctsm.org.mx/index.php/SyV/article/view/2024_syv37_1-240201 <p>Numerical calculations were performed on NbN/Nb and TiN/Ti nanostructured bilayers. Discrete dipole approximation<br />implemented in the DDSCAT code was utilized. In order to design a TUC (Target Unit Cell) with realistic surfaceroughness<br />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<br />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<br />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<br />plasmonics and nanoelectronics applications.</p> Jorge Alberto Polito Lucas Francisco Javier Flores Ruiz Valentín García Vázquez Ana Lilia González Copyright (c) 2024 The authors; licensee SMCTSM, Mexico. https://creativecommons.org/licenses/by/4.0 2024-02-19 2024-02-19 37 240201 240201 10.47566/2024_syv37_1-240201