Suchergebnisse

In this work, we report on high-pressure Raman scattering measurements in mercury digallium sulfide (HgGa2S4) with defect chalcopyrite structure that have been complemented with lattice dynamics ab initio calculations. Our measurements evidence that this semiconductor exhibits a pressure-induced phase transition from the completely ordered defect chalcopyrite structure to a partially disordered defect stannite structure above 18 GPa which is prior to the transition to the completely disordered rocksalt phase above 23 GPa. Furthermore, a completely disordered zincblende phase is observed below 5 GPa after decreasing pressure from 25 GPa. The disordered zincblende phase undergoes a reversible pressure-induced phase transition to the disordered rocksalt phase above 18 GPa. The sequence of phase transitions here reported for HgGa2S4 evidence the existence of an intermediate phase with partial cation-vacancy disorder between the ordered defect chalcopyrite and the disordered rocksalt phases and the irreversibility of the pressure-induced order-disorder processes occurring in ordered-vacancy compounds. The pressure dependence of the Raman modes of all phases, except the Raman-inactive disordered rocksalt phase, have been measured and discussed. ; This study was supported by the Spanish government MEC under Grant No: MAT2010-21270-C04-01/03/04, by MALTA Consolider Ingenio 2010 project (CSD2007-00045), and by the Vicerrectorado de Investigacion y Desarrollo of the Universidad Politecnica de Valencia (UPV2011-0914 PAID-05-11 and UPV2011-0966 PAID-06-11). E. P.-G., P. R.-H., and A. M. acknowledge computing time provided by Red Espanola de Supercomputacion (RES) and MALTA-Cluster. J.A.S. acknowledges Juan de la Cierva fellowship program for his financial support. ; Vilaplana Cerda, RI.; Robledillo, M.; Gomis Hilario, O.; Sans, J.; Manjón Herrera, FJ.; Pérez-González, E.; Rodríguez-Hernández, P. (2013). Vibrational study of HgGa2S4 under high pressure. Journal of Applied Physics. 113(9):935121-9351210. ...

High-pressure Raman scattering measurements have been carried out in ZnGa2Se4 for both tetragonal defect chalcopyrite and defect stannite structures. Experimental results have been compared with theoretical lattice dynamics ab initio calculations and confirm that both phases exhibit different Raman-active phonons with slightly different pressure dependence. A pressure-induced phase transition to a Raman-inactive phase occurs for both phases; however, the sample with defect chalcopyrite structure requires slightly higher pressures than the sample with defect stannite structure to fully transform into the Raman-inactive phase. On downstroke, the Raman-inactive phase transforms into a phase that could be attributed to a disordered zincblende structure for both original phases; however, the sample with original defect chalcopyrite structure compressed just above 20¿GPa, where the transformation to the Raman-inactive phase is not completed, returns on downstroke mainly to its original structure but shows a new peak that does not correspond to the defect chalcopyrite phase. The pressure dependence of the Raman spectra with this new peak and those of the disordered zincblende phase is also reported and discussed. © 2013 AIP Publishing LLC ; This study was supported by the Spanish government MEC under Grants No. MAT2010-21270-C04-01/03/04, by MALTA Consolider Ingenio 2010 project (CSD2007-00045), and by the Vicerrectorado de Investigacion y Desarrollo of the Universitat Politecnica de Valencia (UPV2011-0914 PAID-05-11 and UPV2011-0966 PAID-06-11). E.P.-G., A.M., and P.R.-H. acknowledge computing time provided by Red Espanola de Supercomputacion (RES) and MALTA-Cluster. ; Vilaplana Cerda, RI.; Gomis Hilario, O.; Pérez-González, E.; Ortiz, HM.; Manjón Herrera, FJ.; Rodríguez-Hernández, P.; Muñoz, A. (2013). High-pressure Raman scattering study of defect chalcopyrite and defect stannite ZnGa2Se4. Journal of Applied Physics. 113:2335011-23350110. https://doi.org/10.1063/1.4810854 ; S ; 2335011 ; 23350110 ; 113 ; A. ...

High-pressure optical absorption measurements have been performed in defect chalcopyrite HgGa2Se4 to investigate the influence of pressure on the bandgap energy and its relation with the pressure-induced order-disorder processes that occur in this ordered-vacancy compound. Two different experiments have been carried out in which the sample undergoes either a partial or a total pressure-induced disorder process at 15.4 and 30.8GPa, respectively. It has been found that the direct bandgap energies of the recovered samples at 1GPa were around 0.15 and 0.23eV smaller than that of the original sample, respectively, and that both recovered samples have different pressure coefficients of the direct bandgap than the original sample. A comprehensive explanation for these results on the basis of pressure-induced order-disorder processes is provided. ; This study was supported by the Spanish government MEC under Grants No: MAT2010-21270-C04-01/03/04 and MAT2013-46649-C4-1/2/3-P, by MALTA Consolider Ingenio 2010 project (CSD2007-00045), by Generalitat Valenciana (GVA-ACOMP-2013-1012 and GVA-ACOMP-2014-243), and by the Vicerrectorado de Investigacion y Desarrollo of the Universitat Politecnica de Valencia (UPV2011-0914 PAID-05-11 and UPV2011-0966 PAID-06-11). E. P.-G., J. L.-S., P. R.-H, and A. M. acknowledge computing time provided by Red Espanola de Supercomputacion (RES) and MALTA-Cluster. J.R.-F. thanks the Alexander von Humboldt foundation for a postdoctoral fellowship. ; Gomis, O.; Vilaplana Cerda, RI.; Manjón Herrera, FJ.; Ruiz-Fuertes, J.; Pérez-González, E.; López-Solano, J.; Bandiello, E. (2015). HgGa2Se4 under high pressure: an optical absorption study. physica status solidi (b). 252(9):2043-2051. https://doi.org/10.1002/pssb.201451714 ; S ; 2043 ; 2051 ; 252 ; 9 ; Bernard, J. E., & Zunger, A. (1988). Ordered-vacancy-compound semiconductors: PseudocubicCdIn2Se4. Physical Review B, 37(12), 6835-6856. doi:10.1103/physrevb.37.6835 ; Jiang, X., & Lambrecht, W. R. L. (2004). Electronic band structure of ordered ...

135181 1351815 111 1 ; S Krämer, V., Siebert, D., & Febbraro, S. (1984). Structure refinement of cadmium gallium selenide CdGa2Se4. Zeitschrift für Kristallographie, 169(1-4), 283-287. doi:10.1524/zkri.1984.169.1-4.283 ; High-pressure optical absorption and Raman scattering measurements have been performed in defect chalcopyrite (DC) CdGa2Se4 up to 22 GPa during two pressure cycles to investigate the pressure-induced order-disorder phase transitions taking place in this ordered-vacancy compound. Our measurements reveal that on decreasing pressure from 22 GPa, the sample does not revert to the initial phase but likely to a disordered zinc blende (DZ) structure the direct bandgap and Raman-active modes of which have been measured during a second upstroke. Our measurements have been complemented with electronic structure and lattice dynamical ab initio calculations. Lattice dynamical calculations have helped us to discuss and assign the symmetries of the Raman modes of the DC phase. Additionally, our electronic band structure calculations have helped us in discussing the order-disorder effects taking place above 6¿8 GPa during the first upstroke. © 2012 American Institute of Physics This study was supported by the Spanish government MICINN under Grant No. MAT2010-21270-C04-01/03/04; by the Generalitat Valenciana (Project No. GV06/151), by MALTA Consolider Ingenio 2010 project (CSD2007-00045), by the Vicerrectorado de Investigacion y Desarrollo of the Universitat Politecnica de Valencia (UPV2012-1469), and by the Spanish MICINN under Project No. CTQ2009-14596-C02-01 and Comunidad de Madrid and the European Social Fund Grant No. S2009/PPQ-1551 4161893 (QUI-MAPRES). E.P-G., J.L-S., A. M., and P.R-H. acknowledge computing time provided by Red Espanola de Supercomputacion (RES) and MALTA-Cluster. Gomis Hilario, O.; Vilaplana Cerda, RI.; Manjón Herrera, FJ.; Pérez-González, E.; López-Solano, J.; Rodríguez-Hernández, P.; Muñoz, A. (2012). High-pressure optical and vibrational properties of CdGa2Se4: Order-disorder ...

High-pressure optical absorption and Raman scattering measurements have been performed in defect chalcopyrite (DC) CdGa2Se4 up to 22 GPa during two pressure cycles to investigate the pressure-induced order-disorder phase transitions taking place in this ordered-vacancy compound. Our measurements reveal that on decreasing pressure from 22 GPa, the sample does not revert to the initial phase but likely to a disordered zinc blende (DZ) structure the direct bandgap and Raman-active modes of which have been measured during a second upstroke. Our measurements have been complemented with electronic structure and lattice dynamical ab initio calculations. Lattice dynamical calculations have helped us to discuss and assign the symmetries of the Raman modes of the DC phase. Additionally, our electronic band structure calculations have helped us in discussing the order-disorder effects taking place above 6¿8 GPa during the first upstroke. © 2012 American Institute of Physics ; This study was supported by the Spanish government MICINN under Grant No. MAT2010-21270-C04-01/03/04; by the Generalitat Valenciana (Project No. GV06/151), by MALTA Consolider Ingenio 2010 project (CSD2007-00045), by the Vicerrectorado de Investigacion y Desarrollo of the Universitat Politecnica de Valencia (UPV2012-1469), and by the Spanish MICINN under Project No. CTQ2009-14596-C02-01 and Comunidad de Madrid and the European Social Fund Grant No. S2009/PPQ-1551 4161893 (QUI-MAPRES). E.P-G., J.L-S., A. M., and P.R-H. acknowledge computing time provided by Red Espanola de Supercomputacion (RES) and MALTA-Cluster. ; Gomis Hilario, O.; Vilaplana Cerda, RI.; Manjón Herrera, FJ.; Pérez-González, E.; López-Solano, J.; Rodríguez-Hernández, P.; Muñoz, A. (2012). High-pressure optical and vibrational properties of CdGa2Se4: Order-disorder processes in adamantine compounds. Journal of Applied Physics. 111(1):135181-1351815. https://doi.org/10.1063/1.3675162 ; S ; 135181 ; 1351815 ; 111 ; 1 ; A. MacKinnon, in Tables of Numerical Data and Functional ...