Pressure induced topological and topological crystalline insulators

[EN] Research on topological and topological crystalline insulators (TCIs) is one of the most intense and exciting topics due to its fascinating fundamental science and potential technological applications. Pressure (strain) is one potential pathway to induce the non-trivial topological phases in some topologically trivial (normal) insulating or semiconducting materials. In the last ten years, there have been substantial theoretical and experimental efforts from condensed-matter scientists to characterize and understand pressure-induced topological quantum phase transitions (TQPTs). In particular, a promising enhancement of the thermoelectric performance through pressure-induced TQPT has been recently realized; thus evidencing the importance of this subject in society. Since the pressure effect can be mimicked by chemical doping or substitution in many cases, these results have opened a new route to develop more efficient materials for harvesting green energy at ambient conditions. Therefore, a detailed understanding of the mechanism of pressure-induced TQPTs in various classes of materials with spin-orbit interaction is crucial to improve their properties for technological implementations. Hence, this review focuses on the emerging area of pressure-induced TQPTs to provide a comprehensive understanding of this subject from both theoretical and experimental points of view. In particular, it covers the Raman signatures of detecting the topological transitions (under pressure), some of the important pressure-induced topological and TCIs of the various classes of spin-orbit coupling materials, and provide future research directions in this interesting field.V R and C N would like to dedicate this review to Professor C N R Rao who has been a mentor and inspiration for us. V R and C N acknowledge the Department of Science and Technology (DST) and JNCASR, India, for financial support. FJM acknowledges project MALTA Consolider Team network (RED2018-102612-T), financed by MINECO/AEI/10.13039/501100003329, I+D+i project PID2019-106383GB-42 financed by MCIN/AEI/10.13039/501100011033, as well as projects PROMETEO/2018/123 (EFIMAT) and CIPROM/2021/075 (GREENMAT) financed by Generalitat Valenciana. We sincerely thank Professor Umesh V Waghmare, Theoretical Sciences Unit, JNCASR, Professor Kanishka Biswas, New Chemistry Unit, JNCASR, Professor Sebastian C Peter, New Chemistry Unit, JNCASR, and Dr Boby Joseph, Elettra Sincrotrone Trieste, Italy for the active collaboration and fruitful discussion on these topics of interest.Rajaji, V.; Manjón, F.; Narayana, C. (2022). Pressure induced topological and topological crystalline insulators. Journal of Physics Condensed Matter. 34(42):1-16. https://doi.org/10.1088/1361-648X/ac8906116344

Metavalent bonding in chalcogenides: DFT-chemical pressure approach

[EN] Understanding the chemical bond nature has attracted considerable attention as it is crucial to analyze and comprehend the different physical and chemical properties of materials. This work is considered a complementary part of our previous work in studying the nature of different types of bonding interactions in a wide variety of molecules and materials using the DFT Chemical Pressure (CP) approach. Recently, a new type of chemical bond, the metavalent bond (MVB), has been defined. We show how the CP formalism can be used to analyze and study the establishment of MVB in two chalcogenides, GeSe and PbSe, in a similar fashion as the electron localization function (ELF) profiles. This is accomplished by analyzing the CP maps of these two chalcogenides at different pressures (up to 40 GPa for GeSe and 10 GPa for PbSe). The CP maps show distinctive features related to the MVB, providing insights into the existence of such chemical interaction in the crystal structure of the two compounds. Similar to ELF profiles, CP maps can visualize and track the strength of the MVB in GeSe and PbSe under pressure.This publication is part of the project MALTA Consolider Team network (RED2018-102612-T), financed by MINECO/AEI/10.13039/501100003329; by I+D+i project PID2019-106383GB-42, financed by MCIN/AEI/10.13039/501100011033; and by project, PROMETEO/2018/123 (EFIMAT), financed by Generalitat Valenciana.Helmy Hassan Osman, H.; Manjón, F. (2022). Metavalent bonding in chalcogenides: DFT-chemical pressure approach. Physical Chemistry Chemical Physics. 24(17):9936-9942. https://doi.org/10.1039/d2cp00954d99369942241

Borates or phosphates? That is the question

[EN] Chemical nomenclature is perceived to be a closed topic. However, this work shows that the identification of polyanionic groups is still ambiguous and so is the nomenclature for some ternary compounds. Two examples, boron phosphate (BPO4) and boron arsenate (BAsO4), which were assigned to the large phosphate and arsenate families, respectively, nearly a century ago, are explored. The analyses show that these two compounds should be renamed phosphorus borate (PBO4) and arsenic borate (AsBO4). Beyond epistemology, this has pleasing consequences at several levels for the predictive character of chemistry. It paves the way for future work on the possible syntheses of SbBO4 and BiBO4, and it also renders previous structure field maps completely predictive, allowing us to foresee the structure and phase transitions of NbBO4 and TaBO4. Overall, this work demonstrates that quantum mechanics calculations can contribute to the improvement of current chemical nomenclature. Such revisitation is necessary to classify compounds and understand their properties, leading to the main final aim of a chemist: predicting new compounds, their structures and their transformations.This research was partially supported by Spanish MINECO (grant Nos. MAT2015-71070-REDC and MAT2016-75586-C4-2-P, and MALTA Consolider Team RED2018-102612-T) and Generalitat Valenciana (grant No. PROMETEO/2018/123-EFIMAT). J. Contreras-Garci ' a thanks CALSIMLAB (public grant No. ANR-11-LABX-0037-01), overseen by the French National Research Agency (ANR) as part of the Investissements d'Avenir program (grant No. ANR-11-IDEX-0004-02). M. Marque ' s acknowledges support from the ERC grant `Hecate' and computational resources provided by the UKCP consortium under EPSRC grant EP/P022561/1.Contreras-García, J.; Izquierdo-Ruiz, F.; Marqués, M.; Manjón, F. (2020). Borates or phosphates? That is the question. Acta Crystallographica Section A: Foundations and Advances. 76:197-205. https://doi.org/10.1107/S2053273319016826S19720576Abraham, R. H. & Marsden, J. E. (1994). Foundations of Mechanics. Reading: Addison Wesley.Alinger, N. L., Clark, T., Gasteiger, J., Kollman, P. A., Schaefer, H. F. III, Schreiner, P. R. & Schleyer, von R. (1998). Encyclopedia of Computational Chemistry, edited by R. F. W. Bader. Chichester: Wiley.Bader, R. F. W. (1990). Atoms in Molecules, a Quantum Theory. Oxford: Clarendon.Bader, R. F. W. (1994). Principle of stationary action and the definition of a proper open system. Physical Review B, 49(19), 13348-13356. doi:10.1103/physrevb.49.13348Bastide, J. P. (1987). Systématique simplifiée des composés ABX4 (X = O2−, F−) et evolution possible de leurs structures cristallines sous pression. Journal of Solid State Chemistry, 71(1), 115-120. doi:10.1016/0022-4596(87)90149-6Bayer, G. (1972). Thermal expansion of ABO4-compounds with zircon- and scheelite structures. Journal of the Less Common Metals, 26(2), 255-262. doi:10.1016/0022-5088(72)90045-8Blasse, G., & Van Den Heuvel, G. P. M. (1973). Some optical properties of tantalum borate (tabo4), a compound with unusual coordinations. Physica Status Solidi (a), 19(1), 111-117. doi:10.1002/pssa.2210190109Boyd, R. J. & Matta, C. F. (2007). Editors. The Quantum Theory of Atoms in Molecules. From Solid State to DNA and Drug Design. Weinheim: Wiley-VCH.Brill, R., & Debretteville, A. P. (1955). On the chemical bond type in AlPO4. Acta Crystallographica, 8(9), 567-570. doi:10.1107/s0365110x5500176xDachille, F., & Glasser, L. S. D. (1959). High pressure forms of BPO4 and BAsO4; quartz analogues. Acta Crystallographica, 12(10), 820-821. doi:10.1107/s0365110x59002365Dachille, F., & Roy, R. (1959). High-pressure region of the silica isotypes. Zeitschrift für Kristallographie, 111(1-6), 451-461. doi:10.1524/zkri.1959.111.1-6.451Demartin, F., Diella, V., Gramaccioli, C. M., & Pezzotta, F. (2001). Schiavinatoite, (Nb,Ta)BO4, the Nb analogue of behierite. European Journal of Mineralogy, 13(1), 159-165. doi:10.1127/0935-1221/01/0013-0159Depero, L. E., & Sangaletti, L. (1997). Cation Sublattice and Coordination Polyhedra inABO4Type of Structures. Journal of Solid State Chemistry, 129(1), 82-91. doi:10.1006/jssc.1996.7234Errandonea, D., & Manjón, F. J. (2008). Pressure effects on the structural and electronic properties of ABX4 scintillating crystals. Progress in Materials Science, 53(4), 711-773. doi:10.1016/j.pmatsci.2008.02.001Fukunaga, O., & Yamaoka, S. (1979). Phase transformations in ABO 4 type compounds under high pressure. Physics and Chemistry of Minerals, 5(2), 167-177. doi:10.1007/bf00307551Gázquez, J. L., & Ortiz, E. (1984). Electronegativities and hardnesses of open shell atoms. The Journal of Chemical Physics, 81(6), 2741-2748. doi:10.1063/1.447946Geerlings, P., De Proft, F., & Langenaeker, W. (2003). Conceptual Density Functional Theory. Chemical Reviews, 103(5), 1793-1874. doi:10.1021/cr990029pGenoni, A., Bučinský, L., Claiser, N., Contreras‐García, J., Dittrich, B., Dominiak, P. M., … Grabowsky, S. (2018). Quantum Crystallography: Current Developments and Future Perspectives. Chemistry – A European Journal, 24(43), 10881-10905. doi:10.1002/chem.201705952Gibbs, G. V., Cox, D. F., Boisen, M. B., Downs, R. T., & Ross, N. L. (2003). The electron localization function: a tool for locating favorable proton docking sites in the silica polymorphs. Physics and Chemistry of Minerals, 30(5), 305-316. doi:10.1007/s00269-003-0318-2Gramaccioli, C. M. (2000). Un nuovo minerale: la schiavinatoite. Rendiconti Lincei, 11(4), 197-199. doi:10.1007/bf02904665Haines, J., Chateau, C., Léger, J. M., Bogicevic, C., Hull, S., Klug, D. D., & Tse, J. S. (2003). Collapsing Cristobalitelike Structures in Silica Analogues at High Pressure. Physical Review Letters, 91(1). doi:10.1103/physrevlett.91.015503Hazen, R. M., & Finger, L. W. (1979). Bulk modulus-volume relationship for cation-anion polyhedra. Journal of Geophysical Research: Solid Earth, 84(B12), 6723-6728. doi:10.1029/jb084ib12p06723Hazen, R. M., Finger, L. W., & Mariathasan, J. W. E. (1985). High-pressure crystal chemistry of scheelite-type tungstates and molybdates. Journal of Physics and Chemistry of Solids, 46(2), 253-263. doi:10.1016/0022-3697(85)90039-3IUPAC (1970). Nomenclature of Inorganic Solids. Definitive Rules. 3rd ed. London: International Union of Pure and Applied Chemistry.Kniep, R., Gözel, G., Eisenmann, B., Röhr, C., Asbrand, M., & Kizilyalli, M. (1994). Borophosphates—A Neglected Class of Compounds: Crystal Structures of MII[BPO5](MII Ca, Sr) and Ba3[BP3O12]. Angewandte Chemie International Edition in English, 33(7), 749-751. doi:10.1002/anie.199407491Kresse, G., & Joubert, D. (1999). From ultrasoft pseudopotentials to the projector augmented-wave method. Physical Review B, 59(3), 1758-1775. doi:10.1103/physrevb.59.1758Lashin, V. E., Khritokhin, N. A., & Andreev, O. V. (2012). Structure maps of ABX4 inorganic compounds. Russian Journal of Inorganic Chemistry, 57(12), 1584-1587. doi:10.1134/s0036023612120133Léger, J. M., Haines, J., Chateau, C., Bocquillon, G., Schmidt, M. W., Hull, S., … Marchand, R. (2001). Phosphorus oxynitride PON, a silica analogue: structure and compression of the cristobalite-like phase; P  - T phase diagram. Physics and Chemistry of Minerals, 28(6), 388-398. doi:10.1007/s002690100161Liu, L. (1982). Phase transformations in MSiO4 compounds at high pressures and their geophysical implications. Earth and Planetary Science Letters, 57(1), 110-116. doi:10.1016/0012-821x(82)90177-7Martín Pendás, A., Costales, A., Blanco, M. A., Recio, J. M., & Luaña, V. (2000). Local compressibilities in crystals. Physical Review B, 62(21), 13970-13978. doi:10.1103/physrevb.62.13970Monkhorst, H. J., & Pack, J. D. (1976). Special points for Brillouin-zone integrations. Physical Review B, 13(12), 5188-5192. doi:10.1103/physrevb.13.5188Mori-Sánchez, P., Pendás, A. M., & Luaña, V. (2001). Polarity inversion in the electron density of BP crystal. Physical Review B, 63(12). doi:10.1103/physrevb.63.125103Muller, O., & Roy, R. (1973). Phase transitions among the ABX4compounds*,1. Zeitschrift für Kristallographie, 138(138), 237-253. doi:10.1524/zkri.1973.138.138.237O’Keeffe, M., & Hyde, B. G. (1976). Cristobalites and topologically-related structures. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 32(11), 2923-2936. doi:10.1107/s0567740876009308Otero-de-la-Roza, A., Blanco, M. A., Pendás, A. M., & Luaña, V. (2009). Critic: a new program for the topological analysis of solid-state electron densities. Computer Physics Communications, 180(1), 157-166. doi:10.1016/j.cpc.2008.07.018Otero-de-la-Roza, A., Johnson, E. R., & Contreras-García, J. (2012). Revealing non-covalent interactions in solids: NCI plots revisited. Physical Chemistry Chemical Physics, 14(35), 12165. doi:10.1039/c2cp41395gPauling, L. (1929). THE PRINCIPLES DETERMINING THE STRUCTURE OF COMPLEX IONIC CRYSTALS. Journal of the American Chemical Society, 51(4), 1010-1026. doi:10.1021/ja01379a006Pauling, L. (1960). The Nature of the Chemical Bond and the Structure of Molecules and Crystals: An Introduction to Modern Structural Chemistry, 3rd ed., pp. 543-562. Ithaca: Cornell University Press.Perdew, J. P., Burke, K., & Ernzerhof, M. (1996). Generalized Gradient Approximation Made Simple. Physical Review Letters, 77(18), 3865-3868. doi:10.1103/physrevlett.77.3865Rahm, M., Zeng, T., & Hoffmann, R. (2018). Electronegativity Seen as the Ground-State Average Valence Electron Binding Energy. Journal of the American Chemical Society, 141(1), 342-351. doi:10.1021/jacs.8b10246Range, K.-J., Wildenauer, M., & Heyns, A. M. (1988). Extremely Short Non-Bonding Oxygen?Oxygen Distances: The Crystal Structures of NbBO4, NaNb3O8, and NaTa3O8. Angewandte Chemie International Edition in English, 27(7), 969-971. doi:10.1002/anie.198809691Recio, J. M., Franco, R., Martín Pendás, A., Blanco, M. A., Pueyo, L., & Pandey, R. (2001). Theoretical explanation of the uniform compressibility behavior observed in oxide spinels. Physical Review B, 63(18). doi:10.1103/physrevb.63.184101Schulze, G. E. R. (1933). Die Kristallstruktur von BPO4 und BAsO4. Die Naturwissenschaften, 21(30), 562-562. doi:10.1007/bf01503856Scott, H. P., Williams, Q., & Knittle, E. (2001). Ultralow Compressibility Silicate without Highly Coordinated Silicon. Physical Review Letters, 88(1). doi:10.1103/physrevlett.88.015506Shannon, R. D. (1976). Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallographica Section A, 32(5), 751-767. doi:10.1107/s0567739476001551Stubican, V. S., & Roy, R. (1963). High-pressure scheelite-structure polymorphs of rare-earth vanadates and arsenates. Zeitschrift für Kristallographie, 119(1-2), 90-97. doi:10.1524/zkri.1963.119.1-2.90Vinet, P., Ferrante, J., Smith, J. R. & Rose, J. H. (1986). J. Phys. C: Solid State Phys. L, 19, 467.Vorres, K. S. (1962). Correlating ABO4 compound structures. Journal of Chemical Education, 39(11), 566. doi:10.1021/ed039p566Yang, W., Parr, R. G., & Uytterhoeven, L. (1987). New relation between hardness and compressibility of minerals. Physics and Chemistry of Minerals, 15(2), 191-195. doi:10.1007/bf00308783Zhang, J., Song, L., Sist, M., Tolborg, K., & Iversen, B. B. (2018). Chemical bonding origin of the unexpected isotropic physical properties in thermoelectric Mg3Sb2 and related materials. Nature Communications, 9(1). doi:10.1038/s41467-018-06980-

Combined Experimental and Theoretical Studies: Lattice-Dynamical Studies at High Pressures with the Help of Ab Initio Calculations

[EN] Lattice dynamics studies are important for the proper characterization of materials, since these studies provide information on the structure and chemistry of materials via their vibrational properties. These studies are complementary to structural characterization, usually by means of electron, neutron, or X-ray diffraction measurements. In particular, Raman scattering and infrared absorption measurements are very powerful, and are the most common and easy techniques to obtain information on the vibrational modes at the Brillouin zone center. Unfortunately, many materials, like most minerals, cannot be obtained in a single crystal form, and one cannot play with the different scattering geometries in order to make a complete characterization of the Raman scattering tensor of the material. For this reason, the vibrational properties of many materials, some of them known for millennia, are poorly known even under room conditions. In this paper, we show that, although it seems contradictory, the combination of experimental and theoretical studies, like Raman scattering experiments conducted at high pressure and ab initio calculations, is of great help to obtain information on the vibrational properties of materials at different pressures, including at room pressure. The present paper does not include new experimental or computational results. Its focus is on stressing the importance of combined experimental and computational approaches to understand materials properties. For this purpose, we show examples of materials already studied in different fields, including some hot topic areas such as phase change materials, thermoelectric materials, topological insulators, and new subjects as metavalent bonding.This publication is part of the project MALTA Consolider Team network (RED2018-102612-T), financed by MINECO/AEI/ 10.13039/501100003329; by I+D+i projects PID2019-106383GB-42/43 and FIS2017-83295-P, financed by MCIN/AEI/10.13039/501100011033; by project PROMETEO/2018/123 (EFIMAT), financed by Generalitat Valenciana. J.A.S. acknowledges the Ramon y Cajal fellowship (RYC-2015-17482) for financial support.Manjón, F.; Sans-Tresserras, JÁ.; Rodríguez-Hernández, P.; Muñoz, A. (2021). Combined Experimental and Theoretical Studies: Lattice-Dynamical Studies at High Pressures with the Help of Ab Initio Calculations. Minerals. 11(11):1-17. https://doi.org/10.3390/min11111283S117111

Pressure-Induced Phase Transitions in Sesquioxides

[EN] Pressure is an important thermodynamic parameter, allowing the increase of matter density by reducing interatomic distances that result in a change of interatomic interactions. In this context, the long range in which pressure can be changed (over six orders of magnitude with respect to room pressure) may induce structural changes at a much larger extent than those found by changing temperature or chemical composition. In this article, we review the pressure-induced phase transitions of most sesquioxides, i.e., A(2)O(3) compounds. Sesquioxides constitute a big subfamily of ABO(3) compounds, due to their large diversity of chemical compositions. They are very important for Earth and Materials Sciences, thanks to their presence in our planet's crust and mantle, and their wide variety of technological applications. Recent discoveries, hot spots, controversial questions, and future directions of research are highlighted.This research was funded by Spanish Ministerio de Ciencia, Innovacion y Universidades under grants MAT2016-75586-C4-1/2/3-P, FIS2017-83295-P, PGC2018-094417-B-100, and RED2018-102612-T (MALTA-Consolider-Team network) and by Generalitat Valenciana under grant PROMETEO/2018/123 (EFIMAT). J. A. S. also acknowledges Ramon y Cajal Fellowship for financial support (RYC-2015-17482).Manjón, F.; Sans-Tresserras, JÁ.; Ibáñez, J.; Pereira, ALDJ. (2019). Pressure-Induced Phase Transitions in Sesquioxides. Crystals. 9(12):1-32. https://doi.org/10.3390/cryst9120630S132912Adachi, G., & Imanaka, N. (1998). The Binary Rare Earth Oxides. Chemical Reviews, 98(4), 1479-1514. doi:10.1021/cr940055hZINKEVICH, M. (2007). Thermodynamics of rare earth sesquioxides. Progress in Materials Science, 52(4), 597-647. doi:10.1016/j.pmatsci.2006.09.002Manjón, F. J., & Errandonea, D. (2008). Pressure-induced structural phase transitions in materials and earth sciences. physica status solidi (b), 246(1), 9-31. doi:10.1002/pssb.200844238Hoekstra, H. R., & Gingerich, K. A. (1964). High-Pressure B-Type Polymorphs of Some Rare-Earth Sesquioxides. Science, 146(3648), 1163-1164. doi:10.1126/science.146.3648.1163Sawyer, J. O., Hyde, B. G., & Eyring, L. (1965). Pressure and Polymorphism in the Rare Earth Sesquioxides. Inorganic Chemistry, 4(3), 426-427. doi:10.1021/ic50025a043Vegas, A., & Isea, R. (1998). Distribution of the M-M Distances in the Rare Earth Oxides. Acta Crystallographica Section B Structural Science, 54(6), 732-740. doi:10.1107/s0108768198003759Jiang, S., Liu, J., Lin, C., Bai, L., Xiao, W., Zhang, Y., … Tang, L. (2010). Pressure-induced phase transition in cubic Lu2O3. Journal of Applied Physics, 108(8), 083541. doi:10.1063/1.3499301Meyer, C., Sanchez, J. P., Thomasson, J., & Itié, J. P. (1995). Mössbauer and energy-dispersive x-ray-diffraction studies of the pressure-induced crystallographic phase transition inC-typeYb2O3. Physical Review B, 51(18), 12187-12193. doi:10.1103/physrevb.51.12187Pandey, S. D., Samanta, K., Singh, J., Sharma, N. D., & Bandyopadhyay, A. K. (2013). Anharmonic behavior and structural phase transition in Yb2O3. AIP Advances, 3(12), 122123. doi:10.1063/1.4858421Sahu, P. C., Lonappan, D., & Shekar, N. V. C. (2012). High Pressure Structural Studies on Rare-Earth Sesquioxides. Journal of Physics: Conference Series, 377, 012015. doi:10.1088/1742-6596/377/1/012015Irshad, K. A., Anees, P., Sahoo, S., Sanjay Kumar, N. R., Srihari, V., Kalavathi, S., & Chandra Shekar, N. V. (2018). Pressure induced structural phase transition in rare earth sesquioxide Tm2O3: Experiment and ab initio calculations. Journal of Applied Physics, 124(15), 155901. doi:10.1063/1.5049223Yan, D., Wu, P., Zhang, S. P., Liang, L., Yang, F., Pei, Y. L., & Chen, S. (2013). Assignments of the Raman modes of monoclinic erbium oxide. Journal of Applied Physics, 114(19), 193502. doi:10.1063/1.4831663Ren, X., Yan, X., Yu, Z., Li, W., & Wang, L. (2017). Photoluminescence and phase transition in Er2O3 under high pressure. Journal of Alloys and Compounds, 725, 941-945. doi:10.1016/j.jallcom.2017.07.219Lonappan, D., Shekar, N. V. C., Ravindran, T. R., & Sahu, P. C. (2010). High-pressure phase transition in Ho2O3. Materials Chemistry and Physics, 120(1), 65-67. doi:10.1016/j.matchemphys.2009.10.022Jiang, S., Liu, J., Li, X., Bai, L., Xiao, W., Zhang, Y., … Tang, L. (2011). Phase transformation of Ho2O3at high pressure. Journal of Applied Physics, 110(1), 013526. doi:10.1063/1.3603027Pandey, S. D., Samanta, K., Singh, J., Sharma, N. D., & Bandyopadhyay, A. K. (2014). Raman scattering of rare earth sesquioxide Ho2O3: A pressure and temperature dependent study. Journal of Applied Physics, 116(13), 133504. doi:10.1063/1.4896832Yan, X., Ren, X., He, D., Chen, B., & Yang, W. (2014). Mechanical behaviors and phase transition of Ho2O3nanocrystals under high pressure. Journal of Applied Physics, 116(3), 033507. doi:10.1063/1.4890341Sharma, N. D., Singh, J., Dogra, S., Varandani, D., Poswal, H. K., Sharma, S. M., & Bandyopadhyay, A. K. (2011). Pressure-induced anomalous phase transformation in nano-crystalline dysprosium sesquioxide. Journal of Raman Spectroscopy, 42(3), 438-444. doi:10.1002/jrs.2720Jiang, S., Liu, J., Lin, C., Bai, L., Zhang, Y., Li, X., … Wang, H. (2013). Structural transformations in cubic Dy2O3 at high pressures. Solid State Communications, 169, 37-41. doi:10.1016/j.ssc.2013.06.027Chen, H., He, C., Gao, C., Ma, Y., Zhang, J., Wang, X., … Zou, G. (2007). The structural transition of Gd2O3nanoparticles induced by high pressure. Journal of Physics: Condensed Matter, 19(42), 425229. doi:10.1088/0953-8984/19/42/425229Chen, C.-S., Cheung, K., & Yuan, T.-C. (2007). Novel collider signatures for Little Higgs dark matter models. Physics Letters B, 644(2-3), 158-164. doi:10.1016/j.physletb.2006.11.050Zhang, F. X., Lang, M., Wang, J. W., Becker, U., & Ewing, R. C. (2008). Structural phase transitions of cubicGd2O3at high pressures. Physical Review B, 78(6). doi:10.1103/physrevb.78.064114Dilawar, N., Varandani, D., Mehrotra, S., Poswal, H. K., Sharma, S. M., & Bandyopadhyay, A. K. (2008). Anomalous high pressure behaviour in nanosized rare earth sesquioxides. Nanotechnology, 19(11), 115703. doi:10.1088/0957-4484/19/11/115703Dilawar, N., Varandani, D., Pandey, V. P., Kumar, M., Shivaprasad, S. M., Sharma, P. K., & Bandyopadhyay, A. K. (2006). Structural Transition in Nanostructured Eu2O3 Under High Pressures. Journal of Nanoscience and Nanotechnology, 6(1), 105-113. doi:10.1166/jnn.2006.17913Guo, Q., Zhao, Y., Jiang, C., Mao, W. L., & Wang, Z. (2008). Phase transformation in Sm2O3 at high pressure: In situ synchrotron X-ray diffraction study and ab initio DFT calculation. Solid State Communications, 145(5-6), 250-254. doi:10.1016/j.ssc.2007.11.019Jiang, S., Liu, J., Lin, C., Li, X., & Li, Y. (2013). High-pressure x-ray diffraction and Raman spectroscopy of phase transitions in Sm2O3. Journal of Applied Physics, 113(11), 113502. doi:10.1063/1.4795504Liu, D., Lei, W., Li, Y., Ma, Y., Hao, J., Chen, X., … Zou, G. (2009). High-Pressure Structural Transitions of Sc2O3by X-ray Diffraction, Raman Spectra, and Ab Initio Calculations. Inorganic Chemistry, 48(17), 8251-8256. doi:10.1021/ic900889vOvsyannikov, S. V., Bykova, E., Bykov, M., Wenz, M. D., Pakhomova, A. S., Glazyrin, K., … Dubrovinsky, L. (2015). Structural and vibrational properties of single crystals of Scandia, Sc2O3 under high pressure. Journal of Applied Physics, 118(16), 165901. doi:10.1063/1.4933391Bai, X., Song, H. W., Liu, B. B., Hou, Y. Y., Pan, G. H., & Ren, X. G. (2008). Effects of High Pressure on the Luminescent Properties of Nanocrystalline and Bulk Y2O3:Eu3+. Journal of Nanoscience and Nanotechnology, 8(3), 1404-1409. doi:10.1166/jnn.2008.351Jovanić, B. R., Dramićanin, M., Viana, B., Panić, B., & Radenković, B. (2008). High-pressure optical studies of Y2O3:Eu3+nanoparticles. Radiation Effects and Defects in Solids, 163(12), 925-931. doi:10.1080/10420150802082705Wang, L., Pan, Y., Ding, Y., Yang, W., Mao, W. L., Sinogeikin, S. V., … Mao, H. (2009). High-pressure induced phase transitions of Y2O3 and Y2O3:Eu3+. Applied Physics Letters, 94(6), 061921. doi:10.1063/1.3082082Wang, L., Yang, W., Ding, Y., Ren, Y., Xiao, S., Liu, B., … Mao, H. (2010). Size-Dependent Amorphization of NanoscaleY2O3at High Pressure. Physical Review Letters, 105(9). doi:10.1103/physrevlett.105.095701Dai, R. C., Zhang, Z. M., Zhang, C. C., & Ding, Z. J. (2010). Photoluminescence and Raman Studies of Y2O3:Eu3+ Nanotubes Under High Pressure. Journal of Nanoscience and Nanotechnology, 10(11), 7629-7633. doi:10.1166/jnn.2010.2752DAI, R., WANG, Z., ZHANG, Z., & DING, Z. (2010). Photoluminescence study of SiO2 coated Eu3+:Y2O3 core-shells under high pressure. Journal of Rare Earths, 28, 241-245. doi:10.1016/s1002-0721(10)60275-xYusa, H., Tsuchiya, T., Sata, N., & Ohishi, Y. (2010). Dense Yttria Phase Eclipsing the A-Type Sesquioxide Structure: High-Pressure Experiments and ab initio Calculations. Inorganic Chemistry, 49(10), 4478-4485. doi:10.1021/ic100042zBose, P. P., Gupta, M. K., Mittal, R., Rols, S., Achary, S. N., Tyagi, A. K., & Chaplot, S. L. (2012). High Pressure Phase Transitions in Yttria, Y2O3. Journal of Physics: Conference Series, 377, 012036. doi:10.1088/1742-6596/377/1/012036Srivastava, A. M., Renero-Lecuna, C., Santamaría-Pérez, D., Rodríguez, F., & Valiente, R. (2014). Pressure-induced Pr3+ 3P0 luminescence in cubic Y2O3. Journal of Luminescence, 146, 27-32. doi:10.1016/j.jlumin.2013.09.028Zhang, Q., Wu, X., & Qin, S. (2017). Pressure-induced phase transition of B-type Y 2 O 3. Chinese Physics B, 26(9), 090703. doi:10.1088/1674-1056/26/9/090703Chen, G., Peterson, J. R., & Brister, K. E. (1994). An Energy-Dispersive X-Ray Diffraction Study of Monoclinic Eu2O3 under Pressure. Journal of Solid State Chemistry, 111(2), 437-439. doi:10.1006/jssc.1994.1250Atou, T., Kusaba, K., Tsuchida, Y., Utsumi, W., Yagi, T., & Syono, Y. (1989). Reversible B-type - A-type transition of Sm2O3 under high pressure. Materials Research Bulletin, 24(9), 1171-1176. doi:10.1016/0025-5408(89)90076-7Hongo, T., Kondo, K., Nakamura, K. G., & Atou, T. (2007). High pressure Raman spectroscopic study of structural phase transition in samarium oxide. Journal of Materials Science, 42(8), 2582-2585. doi:10.1007/s10853-006-1417-5Guo, Q., Zhao, Y., Jiang, C., Mao, W. L., Wang, Z., Zhang, J., & Wang, Y. (2007). Pressure-Induced Cubic to Monoclinic Phase Transformation in Erbium Sesquioxide Er2O3. Inorganic Chemistry, 46(15), 6164-6169. doi:10.1021/ic070154gPandey, K. K., Garg, N., Mishra, A. K., & Sharma, S. M. (2012). High pressure phase transition in Nd2O3. Journal of Physics: Conference Series, 377, 012006. doi:10.1088/1742-6596/377/1/012006Jiang, S., Liu, J., Bai, L., Li, X., Li, Y., He, S., … Liang, D. (2018). Anomalous compression behaviour in Nd2O3 studied by x-ray diffraction and Raman spectroscopy. AIP Advances, 8(2), 025019. doi:10.1063/1.5018020Lipp, M. J., Jeffries, J. R., Cynn, H., Park Klepeis, J.-H., Evans, W. J., Mortensen, D. R., … Chow, P. (2016). Comparison of the high-pressure behavior of the cerium oxidesCe2O3andCeO2. Physical Review B, 93(6). doi:10.1103/physrevb.93.064106Hirosaki, N., Ogata, S., & Kocer, C. (2003). Ab initio calculation of the crystal structure of the lanthanide Ln2O3 sesquioxides. Journal of Alloys and Compounds, 351(1-2), 31-34. doi:10.1016/s0925-8388(02)01043-5Marsella, L., & Fiorentini, V. (2004). Structure and stability of rare-earth and transition-metal oxides. Physical Review B, 69(17). doi:10.1103/physrevb.69.172103Petit, L., Svane, A., Szotek, Z., & Temmerman, W. M. (2005). First-principles study of rare-earth oxides. Physical Review B, 72(20). doi:10.1103/physrevb.72.205118WU, B., ZINKEVICH, M., WANG, C., & ALDINGER, F. (2006). Ab initio energetic study of oxide ceramics with rare-earth elements. Rare Metals, 25(5), 549-555. doi:10.1016/s1001-0521(06)60097-1Singh, N., Saini, S. M., Nautiyal, T., & Auluck, S. (2006). Electronic structure and optical properties of rare earth sesquioxides (R2O3, R=La, Pr, and Nd). Journal of Applied Physics, 100(8), 083525. doi:10.1063/1.2353267Mikami, M., & Nakamura, S. (2006). Electronic structure of rare-earth sesquioxides and oxysulfides. Journal of Alloys and Compounds, 408-412, 687-692. doi:10.1016/j.jallcom.2005.01.068Wu, B., Zinkevich, M., Aldinger, F., Wen, D., & Chen, L. (2007). Ab initio study on structure and phase transition of A- and B-type rare-earth sesquioxides Ln2O3 (Ln=La–Lu, Y, and Sc) based on density function theory. Journal of Solid State Chemistry, 180(11), 3280-3287. doi:10.1016/j.jssc.2007.09.022Rahm, M., & Skorodumova, N. V. (2009). Phase stability of the rare-earth sesquioxides under pressure. Physical Review B, 80(10). doi:10.1103/physrevb.80.104105Richard, D., Muñoz, E. L., Rentería, M., Errico, L. A., Svane, A., & Christensen, N. E. (2013). AbinitioLSDA and LSDA+Ustudy of pure and Cd-doped cubic lanthanide sesquioxides. Physical Review B, 88(16). doi:10.1103/physrevb.88.165206Richard, D., Errico, L. A., & Rentería, M. (2016). Structural properties and the pressure-induced C → A phase transition of lanthanide sesquioxides from DFT and DFT + U calculations. Journal of Alloys and Compounds, 664, 580-589. doi:10.1016/j.jallcom.2015.12.236Ogawa, T., Otani, N., Yokoi, T., Fisher, C. A. J., Kuwabara, A., Moriwake, H., … Takata, M. (2018). Density functional study of the phase stability and Raman spectra of Yb2O3, Yb2SiO5 and Yb2Si2O7 under pressure. Physical Chemistry Chemical Physics, 20(24), 16518-16527. doi:10.1039/c8cp02497aPathak, A. K., & Vazhappilly, T. (2018). Ab Initio Study on Structure, Elastic, and Mechanical Properties of Lanthanide Sesquioxides. physica status solidi (b), 255(6), 1700668. doi:10.1002/pssb.201700668Catlow, C. R. A., Guo, Z. X., Miskufova, M., Shevlin, S. A., Smith, A. G. H., Sokol, A. A., … Woodley, S. M. (2010). Advances in computational studies of energy materials. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 368(1923), 3379-3456. doi:10.1098/rsta.2010.0111Caracas, R. (2005). Prediction of a new phase transition in Al2O3at high pressures. Geophysical Research Letters, 32(6). doi:10.1029/2004gl022204Funamori, N. (1997). High-Pressure Transformation of Al2O3. Science, 278(5340), 1109-1111. doi:10.1126/science.278.5340.1109Jephcoat, A. P., Hemley, R. J., & Mao, H. K. (1988). X-ray diffraction of ruby (Al2O3:Cr3+) to 175 GPa. Physica B+C, 150(1-2), 115-121. doi:10.1016/0378-4363(88)90112-xDewaele, A., & Torrent, M. (2013). Equation of state ofα-Al2O3. Physical Review B, 88(6). doi:10.1103/physrevb.88.064107Costa, T. M. H., Gallas, M. R., Benvenutti, E. V., & da Jornada, J. A. H. (1999). Study of Nanocrystalline γ-Al2O3Produced by High-Pressure Compaction. The Journal of Physical Chemistry B, 103(21), 4278-4284. doi:10.1021/jp983791oHart, H. V., & Drickamer, H. G. (1965). Effect of High Pressure on the Lattice Parameters of Al2O3. The Journal of Chemical Physics, 43(7), 2265-2266. doi:10.1063/1.1697121Mashimo, T., Tsumoto, K., Nakamura, K., Noguchi, Y., Fukuoka, K., & Syono, Y. (2000). High-pressure phase transformation of corundum (α-Al2O3) observed under shock compression. Geophysical Research Letters, 27(14), 2021-2024. doi:10.1029/2000gl008490ONO, S., OGANOV, A., KOYAMA, T., & SHIMIZU, H. (2006). Stability and compressibility of the high-pressure phases of Al2O3 up to 200 GPa: Implications for the electrical conductivity of the base of the lower mantle. Earth and Planetary Science Letters, 246(3-4), 326-335. doi:10.1016/j.epsl.2006.04.017Zhao, J., Hearne, G. R., Maaza, M., Laher-Lacour, F., Witcomb, M. J., Le Bihan, T., & Mezouar, M. (2001). Compressibility of nanostructured alumina phases determined from synchrotron x-ray diffraction studies at high pressure. Journal of Applied Physics, 90(7), 3280-3285. doi:10.1063/1.1394915Thomson, K. T., Wentzcovitch, R. M., & Bukowinski, M. S. T. (1996). Polymorphs of Alumina Predicted by First Principles: Putting Pressure on the Ruby Pressure Scale. Science, 274(5294), 1880-1882. doi:10.1126/science.274.5294.1880Jahn, S., Madden, P., & Wilson, M. (2004). Dynamic simulation of pressure-driven phase transformations in crystalline Al2O3. Physical Review B, 69(2). doi:10.1103/physrevb.69.020106Tsuchiya, J., Tsuchiya, T., & Wentzcovitch, R. M. (2005). Transition from theRh2O3(II)-to-CaIrO3structure and the high-pressure-temperature phase diagram of alumina. Physical Review B, 72(2). doi:10.1103/physrevb.72.020103García-Domene, B., Sans, J. A., Gomis, O., Manjón, F. J., Ortiz, H. M., Errandonea, D., … Segura, A. (2014). Pbca-Type In2O3: The High-Pressure Post-Corundum phase at Room Temperature. The Journal of Physical Chemistry C, 118(35), 20545-20552. doi:10.1021/jp5061599Yusa, H., Tsuchiya, T., Sata, N., & Ohishi, Y. (2008). Rh2O3(II)-type structures inGa2O3andIn2O3under high pressure: Experiment and theory. Physical Review B, 77(6). doi:10.1103/physrevb.77.064107Sans, J. A., Vilaplana, R., Errandonea, D., Cuenca-Gotor, V. P., García-Domene, B., Popescu, C., … Muñoz, A. (2017). Structural and vibrational properties of corundum-type In2O3nanocrystals under compression. Nanotechnology, 28(20), 205701. doi:10.1088/1361-6528/aa6a3fLipinska-Kalita, K. E., Chen, B., Kruger, M. B., Ohki, Y., Murowchick, J., & Gogol, E. P. (2003). High-pressure x-ray diffraction studies of the nanostructured transparent vitroceramic mediumK2O−SiO2−Ga2O3. Physical Review B, 68(3). doi:10.1103/physrevb.68.035209Luan, S., Dong, L., & Jia, R. (2019). Analysis of the structural, anisotropic elastic and electronic properties of β-Ga2O3 with various pressures. Journal of Crystal Growth, 505, 74-81. doi:10.1016/j.jcrysgro.2018.09.031Machon, D., McMillan, P. F., Xu, B., & Dong, J. (2006). High-pressure study of theβ-to-αtransition inGa2O3. Physical Review B, 73(9). doi:10.1103/physrevb.73.094125Wang, H., He, Y., Chen, W., Zeng, Y. W., Stahl, K., Kikegawa, T., & Jiang, J. Z. (2010). High-pressure behavior of β-Ga2O3 nanocrystals. Journal of Applied Physics, 107(3), 033520. doi:10.1063/1.3296121Claussen, W. F., & Mackenzie, J. D. (1959). CRYSTALLIZATION OF B2O3AT HIGH PRESSURES1. Journal of the American Chemical Society, 81(4), 1007-1007. doi:10.1021/ja01513a063Brazhkin, V. V., Katayama, Y., Inamura, Y., Kondrin, M. V., Lyapin, A. G., Popova, S. V., & Voloshin, R. N. (2003). Structural transformations in liquid, crystalline, and glassy B2O3 under high pressure. Journal of Experimental and Theoretical Physics Letters, 78(6), 393-397. doi:10.1134/1.1630134Nicholas, J., Sinogeikin, S., Kieffer, J., & Bass, J. (2004). Spectroscopic Evidence of Polymorphism in VitreousB2O3. Physical Review Letters, 92(21). doi:10.1103/physrevlett.92.215701Lee, S. K., Mibe, K., Fei, Y., Cody, G. D., & Mysen, B. O. (2005). Structure ofB2O3Glass at High Pressure: AB11Solid-State NMR Study. Physical Review Letters, 94(16). doi:10.1103/physrevlett.94.165507Gomis, O., Santamaría-Pérez, D., Ruiz-Fuertes, J., Sans, J. A., Vilaplana, R., Ortiz, H. M., … Mollar, M. (2014). High-pressure structural and elastic properties of Tl2O3. Journal of Applied Physics, 116(13), 133521. doi:10.1063/1.4897241Weir, S. T., Mitchell, A. C., & Nellis, W. J. (1996). Electrical resistivity of single‐crystal Al2O3shock‐compressed in the pressure range 91–220 GPa (0.91–2.20 Mbar). Journal of Applied Physics, 80(3), 1522-1525. doi:10.1063/1.362946Syassen, K. (2008). Ruby under pressure. High Pressure Research, 28(2), 75-126. doi:10.1080/08957950802235640Song, H. I., Kim, E. S., & Yoon, K. H. (1988). Phase transformation and characteristics of beta-alumina. Physica B+C, 150(1-2), 148-159. doi:10.1016/0378-4363(88)90117-9ENGÜRLÜ, S., TAŞLIÇUKUR ÖZTÜRK, Z., & KUŞKONMAZ, N. (2017). Investigation of the Production of β-Al2O3 Solid Electrolyte from Seydişehir α-Al2O3. Süleyman Demirel Üniversitesi Fen Bilimleri Enstitüsü Dergisi, 21(3), 816. doi:10.19113/sdufbed.31721Duan, W., Wentzcovitch, R. M., & Thomson, K. T. (1998). First-principles study of high-pressure alumina polymorphs. Physical Review B, 57(17), 10363-10369. doi:10.1103/physrevb.57.10363Oganov, A. R., & Ono, S. (2005). The high-pressure phase of alumina and implications for Earth’s D’’ layer. Proceedings of the National Academy of Sciences, 102(31), 10828-10831. doi:10.1073/pnas.0501800102Hama, J., & Suito, K. (2002). The evidence for the occurrence of two successive transitions in Al2O3 from the analysis of Hugoniot data. High Temperatures-High Pressures, 34(3), 323-334. doi:10.1068/htjr033Ono, S., Kikegawa, T., & Ohishi, Y. (2004). High-pressure phase transition of hematite, Fe2O3. Journal of Physics and Chemistry of Solids, 65(8-9), 1527-1530. doi:10.1016/j.jpcs.2003.11.042Oganov, A. R., & Ono, S. (2004). Theoretical and experimental evidence for a post-perovskite phase of MgSiO3 in Earth’s D″ layer. Nature, 430(6998), 445-448. doi:10.1038/nature02701Vaidya, S. N. (1999). High-pressure high-temperature transitions in nanocrystallineγ Al2O3,γ Fe2O3 and TiO2. Bulletin of Materials Science, 22(3), 287-293. doi:10.1007/bf02749933Mishra, R. S., Lesher, C. E., & Mukherjee, A. K. (1996). High-Pressure Sintering of Nanocrystalline gammaAl2O3. Journal of the American Ceramic Society, 79(11), 2989-2992. doi:10.1111/j.1151-2916.1996.tb08741.xVaidya, S. N., Karunakaran, C., Kamath, R. V., Pillai, K. T., & Vaidya, V. N. (1999). New polymorphs of alumina. High Pressure Research, 16(3), 147-160. doi:10.1080/08957959908200288Vaidya, S. N., Karunakaran, C., Achary, S. N., & Tyagi, A. K. (1999). New polymorphs of alumina: Part II μ and λ alumina. High Pressure Research, 16(4), 265-278. doi:10.1080/08957959908200299Bekheet, M. F., Schwarz, M. R., Lauterbach, S., Kleebe, H.-J., Kro

Negative pressures in CaWO4 nanocrystals

Tetragonal scheelite-type CaWO4 nanocrystals recently prepared by a hydrothermal method show an enhancement of its structural symmetry with the decrease in nanocrystal size. The analysis of the volume dependence of the structural parameters in CaWO4 nanocrystals with the help of ab initio total-energy calculations shows that the enhancement of the symmetry in the scheelite-type nanocrystals is a consequence of the negative pressure exerted on the nanocrystals; i.e., the nanocrystals are under tension. Besides, the behavior of the structural parameters in CaWO4 nanocrystals for sizes below 10 nm suggests an onset of a scheelite-to-zircon phase transformation in good agreement with the predictions from our ab initio calculations. CaWO4 nanocrystals exhibit a reconstructive-type mechanism for the scheelite-to-zircon phase transition that seems to follow the tetragonal path that links both structures. This result is in contrast with the mechanism recently proposed for this transition in bulk ZrSiO4 where the transition goes through an intermediate monoclinic [email protected]

Analysis of the upconversion emission of yttrium orthoaluminate nanoperovskite co-doped with Er3+/Yb3+ ions for thermal sensing applications

[EN] The upconversion emissions of yttrium orthoaluminate nano-perovskite co-doped with Er3+/Yb3+ have been studied. Strong green and red upconversion emissions, which can be observed by naked eyes, were observed when exciting the sample at 980 nm. In particular, the green band was monitored as a function of temperature and the obtained results suggest that this nano-perovskite can be used as an optical temperature sensor by exciting in the infrared range. The viability of YAP: Er3+/Yb3+ nano-perovskite in laser heating applications has been tested and discussed.This research was partially supported MINECO (MAT2013-46649-C4-2/4-P, MAT2015-71070-REDC, and MAT2016-75586-C4-2/4-P), and by the EU-FEDER. M.A. Hernández-Rodríguez thanks to MINECO for FPI grant (BES-2014-068666).Hernández-Rodríguez, M.; Lozano-Gorrín, A.; Lavin, V.; Rodriguez-Mendoza, U.; Martin, I.; Manjón, F. (2018). Analysis of the upconversion emission of yttrium orthoaluminate nanoperovskite co-doped with Er3+/Yb3+ ions for thermal sensing applications. Journal of Luminescence. 202:316-321. https://doi.org/10.1016/j.jlumin.2018.05.078S31632120

High-pressure Raman study of Fe(IO3)3: Soft-mode behavior driven by coordination changes of iodine atoms

This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.jpcc.0c06541.[EN] We report high-pressure Raman spectroscopy studies of Fe(IO3)(3) up to nearly 21 GPa that have been interpreted with the help of density functional theory calculations, which include the calculation of phonon dispersion curves and elastic constants at different pressures. Zero-pressure Raman-active mode frequencies and their pressure dependences have been determined. Modes have been assigned and correlated to atomic movements with the help of calculations. Interestingly, in the high-frequency region, there are several modes that soften under compression. These modes have been identified as internal vibrations of the IO3 coordination polyhedron. Their unusual behavior is a consequence of the changes induced by pressure in the coordination sphere of iodine, which gradually change from a threefold coordination to an almost sixfold coordination under compression. The coordination change is favored by the decrease of the stereoactivity of the iodine lone electron pair so that likely a real sixfold coordination is attained after a first-order phase transition previously reported to occur above 21 GPa. The strong nonlinear behavior found in Raman-active modes as well as in theoretically calculated elastic constants has been discovered to be related to the occurrence of two previously unreported isostructural phase transitions at 1.5-2.0 and 5.7-6.0 GPa as shown by dynamic instabilities close to the Brillouin zone center.This work was supported by the Spanish Ministry of Science, Innovation and Universities, the Spanish Research Agency (AEI), the European Fund for Regional Development (ERDF, FEDER) under grants MAT2016-75586-C4-1/2/3-P, PID2019-106383GB-C41/42/43, and RED2018-102612-T (MALTA Consolider-Team Network), and the Generalitat Valenciana under grant Prometeo/2018/123 (EFIMAT). A.L. and D.E. would like to thank the Generalitat Valenciana for the Ph.D. fellowship GRISOLIAP/2019/025).Liang, A.; Rahman, S.; Rodriguez-Hernandez, P.; Muñoz, A.; Manjón, F.; Nenert, G.; Errandonea, D. (2020). High-pressure Raman study of Fe(IO3)3: Soft-mode behavior driven by coordination changes of iodine atoms. The Journal of Physical Chemistry C. 124(39):21329-21337. https://doi.org/10.1021/acs.jpcc.0c06541S21329213371243

Strong optical nonlinearities in gallium and indium selenides related to inter-valence-band transitions induced by light pulses

A nonlinear optical effect is shown to occur in gallium and indium selenides at photon energies of the order of 1.5 eV. It corresponds to transitions from a lower-energy valence band to the uppermost one when a nonequilibrium degenerate hole gas is created in the latter by a laser pulse. This inter-valence-band transition is allowed by crystal symmetry. Its oscillator strength is estimated through the f-sum rule and turns out to be about two orders of magnitude higher than that of the fundamental transition. The intensity of this effect is stronger when the pump pulse photon energy is close to that of the inter-valence-band transition; a condition that can be fulfilled only in indium selenide. The transient behavior of the sample transmittance is shown to be controlled by the balance between absorption and stimulated emission, which depends on the hole quasi-Fermi level and the gap renormalization due to Coulomb interaction in the electron-hole gas generated by the pump

Oscillations studied with the smartphone ambient light sensor

This paper makes use of a smartphone's ambient light sensor to analyse a system of two coupled springs undergoing either simple or damped oscillatory motion. The period, frequency and stiffness of the spring, together with the damping constant and extinction time, are extracted from light intensity curves obtained using a free Android application. The results demonstrate the instructional value of mobile phone sensors as a tool in the physics laboratory.The authors would like to thank the Institute of Education Sciences, Universitat Politecnica de Valencia (Spain) for the support of the Teaching Innovation Groups, e-MACAFI and MoMa.Sans Tresserras, JÁ.; Manjón Herrera, FJ.; Pereira, A.; Gómez-Tejedor, JA.; Monsoriu Soriano, JC. (2013). Oscillations studied with the smartphone ambient light sensor. European Journal of Physics. 34(6):1349-1354. doi:10.1088/0143-0807/34/6/1349S13491354346Monsoriu, J. A., Giménez, M. H., Riera, J., & Vidaurre, A. (2005). Measuring coupled oscillations using an automated video analysis technique based on image recognition. European Journal of Physics, 26(6), 1149-1155. doi:10.1088/0143-0807/26/6/023Shamim, S., Zia, W., & Anwar, M. S. (2010). Investigating viscous damping using a webcam. American Journal of Physics, 78(4), 433-436. doi:10.1119/1.3298370Ochoa, O. R., & Kolp, N. F. (1997). The computer mouse as a data acquisition interface: Application to harmonic oscillators. American Journal of Physics, 65(11), 1115-1118. doi:10.1119/1.18732Ng, T. W., & Ang, K. T. (2005). The optical mouse for harmonic oscillator experimentation. American Journal of Physics, 73(8), 793-795. doi:10.1119/1.1862634Tomarken, S. L., Simons, D. R., Helms, R. W., Johns, W. E., Schriver, K. E., & Webster, M. S. (2012). Motion tracking in undergraduate physics laboratories with the Wii remote. American Journal of Physics, 80(4), 351-354. doi:10.1119/1.3681904Ballester, J., & Pheatt, C. (2013). Using the Xbox Kinect sensor for positional data acquisition. American Journal of Physics, 81(1), 71-77. doi:10.1119/1.4748853Vannoni, M., & Straulino, S. (2007). Low-cost accelerometers for physics experiments. European Journal of Physics, 28(5), 781-787. doi:10.1088/0143-0807/28/5/001Skeffington, A., & Scully, K. (2012). Simultaneous Tracking of Multiple Points Using a Wiimote. The Physics Teacher, 50(8), 482-484. doi:10.1119/1.4758151Castro-Palacio, J. C., Velázquez-Abad, L., Giménez, F., & Monsoriu, J. A. (2013). A quantitative analysis of coupled oscillations using mobile accelerometer sensors. European Journal of Physics, 34(3), 737-744. doi:10.1088/0143-0807/34/3/737Carlos Castro-Palacio, J., Velázquez-Abad, L., Giménez, M. H., & Monsoriu, J. A. (2013). Using a mobile phone acceleration sensor in physics experiments on free and damped harmonic oscillations. American Journal of Physics, 81(6), 472-475. doi:10.1119/1.4793438Ouseph, P. J., Driver, K., & Conklin, J. (2001). Polarization of light by reflection and the Brewster angle. American Journal of Physics, 69(11), 1166-1168. doi:10.1119/1.1397457Berger, J. (1988). On potential energy, its force field and their measurement along an air track. European Journal of Physics, 9(1), 47-50. doi:10.1088/0143-0807/9/1/00