High-pressure lattice dynamical study of bulk and nanocrystalline In2O3

The effect of pressure on the vibrational properties of bulk and nanocrystallinepowders of cubic bixbyite-type In2O3 has been investigated at room temperature by means of Raman spectroscopy up to 31.6 and 30¿GPa, respectively. We have been able to follow the pressure dependence of up to sixteen and seven Raman modes in bulk and nanocrystalline cubic In2O3, respectively. The experimental frequencies and pressure coefficients of the Raman-active modes of bulk cubic In2O3 at ambient pressure are in good agreement with those predicted by our theoretical ab initio calculations. Furthermore, a comparison of our experimental data with our calculations for the Raman modes in rhombohedral corundum and orthorhombic Rh2O3-II structures and with already reported Raman modes of rhombohedral corundum-type In2O3 at room pressure indicate that Raman scattering measurements provide no experimental evidence of the cubic to rhombohedral or cubic to orthorhombic phase transitions either in bulk material or in nanocrystals up to 30¿GPa. © 2012 American Institute of PhysicsResearch financed by the Spanish MEC under Grant No. MAT2010-21270-C04-01/03/04 and from Vicerrectorado de Investigacion de la Universitat Politecnica de Valencia under Projects UPV2011-0914 PAID-05-11 and UPV2011-0966 PAID-06-11. CONACyT Mexico under the Project J-152153-F and the Marie-Curie Intra-European Fellowship have supported AHR. Supercomputer time has been provided by the Red Espanola de Supercomputacion (RES) and the MALTA cluster. B.G.-D. acknowledges J. Ruiz-Fuertes for enlightening suggestions. We also acknowledge the financial support from the MEC through the FPI program and Juan de la Cierva fellowship.Garcia Domene, B.; Ortiz, HM.; Gomis Hilario, O.; Sans, JA.; Manjón Herrera, FJ.; Muñoz, A.; Rodríguez-Hernández, P.... (2012). High-pressure lattice dynamical study of bulk and nanocrystalline In2O3. Journal of Applied Physics. 112:1235111-1235117. https://doi.org/10.1063/1.4769747S12351111235117112Granqvist, C. G. (1993). Transparent conductive electrodes for electrochromic devices: A review. Applied Physics A Solids and Surfaces, 57(1), 19-24. doi:10.1007/bf00331211Mizoguchi, H., & Woodward, P. M. (2004). Electronic Structure Studies of Main Group Oxides Possessing Edge-Sharing Octahedra:  Implications for the Design of Transparent Conducting Oxides. Chemistry of Materials, 16(25), 5233-5248. doi:10.1021/cm049249wKing, P. D. C., Veal, T. D., Fuchs, F., Wang, C. Y., Payne, D. J., Bourlange, A., … McConville, C. F. (2009). 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Precision restoration: a necessary approach to foster forest recovery in the 21st century

We thank S. Tabik, E. Guirado, and Garnata Drone SL for fruitful debates about the application of remote sensing and artificial intelligence in restoration. E. McKeown looked over the English version of the manuscript. Original drawings were made by J. D. Guerrero. This work was supported by projects RESISTE (P18-RT-1927) from the Consejeria de Economia, Conocimiento, y Universidad from the Junta de Andalucia, and AVA201601.19 (NUTERA-DE I), DETECTOR (A-RNM-256-UGR18), and AVA2019.004 (NUTERA-DE II), cofinanced (80%) by the FEDER Program. F.M.-R. acknowledges the support of the Agreement 4580 between OTRI-UGR and the city council of La Zubia. We thank an anonymous reviewer for helpful comments that improved the manuscript.Forest restoration is currently a primary objective in environmental management policies at a global scale, to the extent that impressive initiatives and commitments have been launched to plant billions of trees. However, resources are limited and the success of any restoration effort should be maximized. Thus, restoration programs should seek to guarantee that what is planted today will become an adult tree in the future, a simple fact that, however, usually receives little attention. Here, we advocate for the need to focus restoration efforts on an individual plant level to increase establishment success while reducing negative side effects by using an approach that we term “precision forest restoration” (PFR). The objective of PFR will be to ensure that planted seedlings or sowed seeds will become adult trees with the appropriate landscape configuration to create functional and self-regulating forest ecosystems while reducing the negative impacts of traditional massive reforestation actions. PFR can take advantage of ecological knowledge together with technologies and methodologies from the landscape scale to the individual- plant scale, and from the more traditional, low-tech approaches to the latest high-tech ones. PFR may be more expensive at the level of individual plants, but will be more cost-effective in the long term if it allows for the creation of resilient forests able to providemultiple ecosystemservices. PFR was not feasible a few years ago due to the high cost and low precision of the available technologies, but it is currently an alternative that might reformulate a wide spectrum of ecosystem restoration activities.Junta de Andalucia P18-RT-1927European Commission AVA201601.19 A-RNM-256-UGR18 AVA2019.004OTRI-UGR 4580city council of La Zubia 458

Lattice dynamics study of HgGa2Se4 at high pressures

We report on Raman scattering measurements in mercury digallium selenide (HgGa2Se4) up to 25 GPa. We also performed, for the low-pressure defect-chalcopyrite structure, lattice-dynamics ab initio calculations at high pressures which agree with experiments. Measurements evidence that the semiconductor HgGa2Se4 exhibits a pressure-induced phase transition above 19 GPa to a previously undetected structure. This transition is followed by a transformation to a Raman-inactive phase above 23.4 GPa. On downstroke from 25 GPa until 2.5 GPa, a broad Raman spectrum was observed, which has been attributed to a fourth phase, and whose pressure dependence was followed during a second upstroke. Candidate structures for the three phases detected under compression are proposed. Finally, we also report and discuss the decomposition of the sample by laser heating at pressures close to 19 GPa. As possible products of decomposition, we have identified at least the formation of trigonal selenium nanoclusters and cinnabar-type HgSe.This study was supported by the Spanish government MEC under Grant No. MAT2010-21270-004-01/03/04, by MALTA Consolider Ingenio 2010 project (CSD2007-00045), by Generalitat Valenciana through project GVA-ACOMP-2013-012, and by the Vicerrectorado de Investigacion y Desarrollo of the Universidad Politecnica de Valencia (UPV2011-0966 and UPV2011-0914). E.P.-G., J.L.-S., A.M., and P.R.-H. acknowledge computing time provided by Red Espanola de Super-computacion (RES) and MALTA-Cluster.Vilaplana Cerda, RI.; Gomis Hilario, O.; Manjón Herrera, FJ.; Ortiz, HM.; Pérez González, E.; López Solano, J.; Rodríguez Hernández, P.... (2013). Lattice dynamics study of HgGa2Se4 at high pressures. Journal of Physical Chemistry C. 117(30):15773-15781. https://doi.org/10.1021/jp402493rS15773157811173

Design of a survey to evaluate problem-based learning methodology in a corrosion course

[EN] Problem Based Learning (PBL) methodology was introduced for the first time in a Corrosion course from the Master of Chemical Engineering of the Universitat Politècnia de València, Spain. Different problems involving all these concepts were designed and presented as primary learning methodology over the entire course. This work is focused on the design of a survey for the students in order to: first, know their opinion about the PBL methodology, indicating the advantages and main drawbacks of it and, second, know if this methodology motivates students to seek out a deeper understanding of concepts. This study presents the survey used to evaluate the PBL methodology used during the corrosion course and discuss the obtained results. It is important to point out that this was the first time that students face up to this kind of methodology in university but the general opinion about the methodology is very positive.Authors would like to express their gratitude to the project PIME: Aprendizaje Basado en Problemas para su aplicación en las áreas de Ingeniería Química y de Materiales (Ref. 27) and to the Instituto de Ciencias de la Educación and the Vicerrectorado de Estudios, Calidad y Acreditación from the Universitat Politècnica de Valencia, for their financial and technical support.Sánchez-Tovar, R.; Fernández-Domene, R.; Lucas-Granados, B.; Blasco-Tamarit, E.; Garcia-Anton, J. (2019). Design of a survey to evaluate problem-based learning methodology in a corrosion course. IATED. 162-165. https://doi.org/10.21125/inted.2019.0078S16216

Influence of annealing atmosphere on photoelectrochemical response of TiO2 nanotubes anodized under controlled hydrodynamic conditions

[EN] The influence of three annealing atmospheres (air, nitrogen and argon) and the use of controlled hydrodynamic conditions (from 0 to 5000 rpm) on morphological, structural, chemical and photoelectrochemical properties of TiO2 nanotubes have been evaluated. For this purpose, different characterization techniques have been used: Field Emission Scanning Electron Microscopy, Raman Confocal Laser Spectroscopy, X-Ray Diffraction, X-Ray Photoelectron Spectroscopy, Incident Photon-to-electron Conversion Efficiency measurements, ultraviolet-visible absorption spectra, Mott-Schottky analysis and photoelectrochemical water splitting tests. According to the results, it can be concluded that both hydrodynamic conditions and annealing in non-oxidizing atmospheres improve the photoelectrochemical response of the TiO2 nanotubes. This fact has been attributed to the oxygen vacancies formed after annealing in argon and nitrogen atmospheres and also to the presence of nitrogen into the TiO2 lattice due to the thermal treatment in the nitrogen atmosphere.The authors would like to express their gratitude for the financial support to the "Generalitat Valenciana (GV/2020/044) " as well as to the "Agencia Estatal de Investigacion" (Project Code: PID2019-105844RB-I00/AEI/10.13039/501100011033) ", for its help in the Laser Raman Microscope acquisition (UPOV08-3E-012) and the co-finance by the European Social Fund. Authors from UV also thank MINECO (MAT2017-84118-C2-1-R project) and FEDER for funding.Blasco-Tamarit, E.; Solsona, B.; Sánchez-Tovar, R.; García-García, D.; Fernández Domene, R.; Garcia-Anton, J. (2021). Influence of annealing atmosphere on photoelectrochemical response of TiO2 nanotubes anodized under controlled hydrodynamic conditions. Journal of Electroanalytical Chemistry. 897:1-13. https://doi.org/10.1016/j.jelechem.2021.11557911389

Indirect charge transfer of holes via surface states in ZnO nanowires for photoelectrocatalytic applications

[EN] In this work, ZnO nanowires with high aspect ratio were obtained by fast and simple electrochemical anodization. Morphological, structural and photoelectrochemical characteristics of the synthesized ZnO nanowires were evaluated by using different techniques: field emission scanning electron microscopy, atomic force microscopy, high resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-VIS spectroscopy, Mott-Schottky analysis and photoelectrochemical impedance spectroscopy. The synthesized ZnO nanowires presented high roughness and high crystallinity. Besides, surface defects were identified in the sample. The value of the donor density (ND) was in the order of 1019 cm-3 in the dark and 1020 cm-3 under illumination. In addition, the ZnO nanowires presented good photosensibility, with a photocurrent density response 85 times higher than a ZnO compact layer, and lower resistance to charge transfer. The charge transfer processes taking place at the ZnO/electrolyte interface were studied, since these processes strongly influence the photoelectrocatalytic efficiency of the material. According to the results, the charge transfer of holes in the synthesized ZnO nanowires occurs indirectly via surface states. In this regard, surface states may be an important feature for photoelectrocatalytic applications since they could provide lower onset voltages and higher anodic current densities.Authors would like to express their gratitude to the Generalitat Valenciana and to the European Social Fund for their financial support within the subvention GJIDI/2018/A/067. Authors also thank to project co-funded by FEDER operational programme 2014-2020 of Comunitat Valenciana (IDIFEDER/18/044). Finally, authors thank to Ministerio de Ciencia e Innovacion-Agencia Estatal de Investigacion (PID2019-105844RB-I00/AEI/10.13039/501100011033) and MINECO for its help in the Laser Raman Microscope acquisition (UPOV08-3E-012) co -financed by the European Social Fund. Authors would also like to ex-press their gratitude for the financial support to the Generalitat Valenciana (GV/2021/011). Authors also thanks MINECO for MAT2017-84118-C2-1-R MCIN/AEI/10.13039/501100011033/project and FEDER Una manera de hacer Europa.Batista-Grau, P.; Fernández Domene, RM.; Sánchez-Tovar, R.; Blasco-Tamarit, E.; Solsona, B.; Garcia-Anton, J. (2022). Indirect charge transfer of holes via surface states in ZnO nanowires for photoelectrocatalytic applications. Ceramics International. 48(15):21856-21867. https://doi.org/10.1016/j.ceramint.2022.04.1702185621867481

Influence of Zn(NO3)2 concentration during the ZnO electrodeposition on TiO2 nanosponges used in photoelectrochemical applications

[EN] TiO2/ZnO hybrid nanostructures were formed by electrochemical anodization of titanium and subsequently ZnO electrodeposition. Different Zn(NO3)(2) concentrations were used for electrodeposition (10-60 mM). A structural, morphological, and compositional characterisation was performed using FE-SEM, TEM, AFM, XRD, UV-Visible spectroscopy, and band gap measurements. It was reported that the morphology of the nanostructures changed with the Zn(NO3)2 concentration. Nanosponges were observed for concentrations from 10 mM to 30 mM whereas at 40 mM the morphology changed to well-defined ZnO hexagonal nanorods. At 50 mM a surface covered by ZnO with undefined rods could be seen and, at 60 mM, a morphology of nanoplatelets was observed. Besides, as Zn (NO3)2 concentration increased, the ZnO amount, the roughness, and the ZnO crystalline size also increased, while the band gap decreased. Electrochemical characterisation of nanostructures was performed by water splitting, stability to photocorrosion, EIS, and Mott-Schottky tests. The optimal samples were TiO2/ZnO hybrid nanostructures electrodeposited with 30 mM Zn(NO3)(2), since they were stable against photocorrosion and, compared to TiO2 nanosponges, showed an increase in photoelectrochemical activity of 204%, a lower resistance to charge transfer, and a higher donor density. Overall, the most efficient samples presented an intermediate Znloading because of a maximization of the TiO2-ZnO interaction and the prevention of the formation of non interacting ZnO structures.The authors would like to thank the financial support to the "Agencia Estatal de Investigacion" (PID2019-105844RB-I00/MCIN/AEI/10.13039/501100011033) and the co-finance by the "European Social Fund". The authors also thank the "Generalitat Valenciana" for its help in the Atomic Force Microscope acquisition (IDIFEDER/2018/044). Pedro Jose Navarro Gazquez wants to show his gratitude for the GRANT PEJ2018-003596-A-AR funded by MCIN/AEI/10.13039/501100011033 and by "ESF Investing in your future". Authors from UV also thank MINECO (MAT2017-84118-C2-1-R project) and FEDER for funding. SCSIE from UV is also acknowledged for TEM and XRD measurements.Navarro-Gázquez, P.; Blasco-Tamarit, E.; Muñoz-Portero, M.; Solsona, B.; Fernández-Domene, M.; Sánchez Tovar, R.; Garcia-Anton, J. (2022). Influence of Zn(NO3)2 concentration during the ZnO electrodeposition on TiO2 nanosponges used in photoelectrochemical applications. Ceramics International. 48(10):14460-14472. https://doi.org/10.1016/j.ceramint.2022.01.3391446014472481

Structural and vibrational behavior of cubic Cu1.80(3)Se cuprous selenide, berzelianite, under compression

[EN] We have performed an experimental study of the crystal structure and lattice dynamics of cubic Cu1.80(3)Se at ambient temperature and high pressures. Two reversible phase transitions were found at 2.9 and 8.7 GPa. The indexation of the angle-dispersive synchrotron x-ray diffraction patterns suggests a large orthorhombic cell and a monoclinic cell for the high-pressure phases. Raman measurements provide additional information on the local structure. The compressibility of the three ambient temperature phases has been determined and compared to that of other sulphides and selenides.This work has been performed under financial support from Spanish MICINN under projects MAT2016-75586-C4-2/3-P, FIS2017-83295-P, and PGC2018-097520-A-I00, as well as under the MALTA Consolider Team network (RED2018-102612-T), from Generalitat Valenciana under project PROMETEO/2018/123-EFIMAT, and from Brazilian Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) under projects 307199/2018-5, 422250/2016-3, and 201050/2012-9. D.S-P. and J.A.S. acknowledge the financial support of the Spanish MINECO for the RyC-2014-15643 and RyC-2015-17482 Ramon y Cajal Grants, respectively. We also thank ALBA synchrotron for funded experiment No. 2012010266.Chulia-Jordan, R.; Santamaria-Perez, D.; Pereira, ALJ.; Garcia-Domene, B.; Vilaplana Cerda, RI.; Sans-Tresserras, JÁ.; Martinez-Garcia, D.... (2020). Structural and vibrational behavior of cubic Cu1.80(3)Se cuprous selenide, berzelianite, under compression. Journal of Alloys and Compounds. 830:154646 - 1-154646 - 8. https://doi.org/10.1016/j.jallcom.2020.154646S154646 - 1154646 - 883

Synthesis and High-Pressure Study of Corundum-Type In₂O₃

This work reports the high-pressure and high-temperature (HP-HT) synthesis of pure rhombohedral (corundum-type) phase of indium oxide (In₂O₃) from its most stable polymorph, cubic bixbyite-type In₂O₃, using a multianvil press. Structural and vibrational properties of corundum-type In₂O₃ (rh-In₂O₃) have been characterized by means of angle-dispersive powder X-ray diffraction and Raman scattering measurements at high pressures which have been compared to structural and lattice dynamics ab initio calculations. The equation of state and the pressure dependence of the Raman-active modes of the corundum-type phase are reported and compared to those of corundum (α-Al₂O₃). It can be concluded that rh-In₂O₃ is stable under compression up to 14 GPa and it gradually transforms to the orthorhombic Rh₂O₃–III structure with Pbca space group (N. 61) between 14 and 26 GPa. The bulk modulus, axial compressibilities, and the pressure range of stability of the corundum-type phase in group IIIA sesquioxides <i>A</i>₂O₃ (<i>A</i> = Al, Ga, and In) are discussed