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The following article appeared in Journal of Applied Physics and may be found at http://dx.doi.org/10.1063/1.4914407 . Authors own version of final article on e-print servers ; We have studied the structural behavior of bismuth phosphate under compression. We performed x-ray powder diffraction measurements up to 31.5 GPa and ab initio calculations. Experiments were carried out on different polymorphs: trigonal (phase I) and monoclinic (phases II and III). Phases I and III, at low pressure (P 0.2-0.8 GPa), transform into phase II, which has a monazite-type structure. At room temperature, this polymorph is stable up to 31.5 GPa. Calculations support these findings and predict the occurrence of an additional transition from the monoclinic monazite-type to a tetragonal scheelite-type structure (phase IV). This transition was experimentally found after the simultaneous application of pressure (28 GPa) and temperature (1500 K), suggesting that at room temperature the transition might by hindered by kinetic barriers. Calculations also predict an additional phase transition at 52 GPa, which exceeds the maximum pressure achieved in the experiments. This transition is from phase IV to an orthorhombic barite-type structure (phase V). We also studied the axial and bulk compressibility of BiPO4. Room-temperature pressure-volume equations of state are reported. BiPO4 was found to be more compressible than isomorphic rare-earth phosphates. The discovered phase IV was determined to be the less compressible polymorph of BiPO4. On the other hand, the theoretically predicted phase V has a bulk modulus comparable with that of monazite-type BiPO4. Finally, the isothermal compressibility tensor for the monazite-type structure is reported at 2.4 GPa showing that the direction of maximum compressibility is in the (0 1 0) plane at approximately 15 degrees (21 degrees) to the a axis for the case of our experimental (theoretical) study. (C) 2015 AIP Publishing LLC. ; Research supported by the Spanish government MINECO under Grant No: ...

Copyright (2011) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. ; We perform Raman-scattering measurements at high hydrostatic pressures on c-face and a-face InN layers to investigate the high-pressure behavior of the zone-center optical phonons of wurtzite InN. Linear pressure coefficients and mode Grneisen parameters are obtained, and the experimental results are compared with theoretical values obtained from ab initio lattice-dynamical calculations. Good agreement is found between the experimental and calculated results. © 2011 American Institute of Physics. ; Work supported by the Spanish MICINN (Projects MAT2010-16116, MAT2008-06873-C02-02, MAT2010-21270-C04-04, and CSD2007-00045), the Catalan Government (BE-DG 2009), and the Spanish Council for Research (PIE2009-CSIC). ; Ibanez, J.; Manjón Herrera, FJ.; Segura, A.; Oliva, R.; Cusco, R.; Vilaplana Cerda, RI.; Yamaguchi, T. (2011). High-pressure Raman scattering in wurtzite indium nitride. Applied Physics Letters. 99:119081-119083. https://doi.org/10.1063/1.3609327 ; S ; 119081 ; 119083 ; 99 ; Veal, T., McConville, C., & Schaff, W. (Eds.). (2009). Indium Nitride and Related Alloys. doi:10.1201/9781420078107 ; Gallinat, C. S., Koblmüller, G., Brown, J. S., Bernardis, S., Speck, J. S., Chern, G. D., … Wraback, M. (2006). In-polar InN grown by plasma-assisted molecular beam epitaxy. Applied Physics Letters, 89(3), 032109. doi:10.1063/1.2234274 ; Li, S. X., Wu, J., Haller, E. E., Walukiewicz, W., Shan, W., Lu, H., & Schaff, W. J. (2003). Hydrostatic pressure dependence of the fundamental bandgap of InN and In-rich group III nitride alloys. Applied Physics Letters, 83(24), 4963-4965. doi:10.1063/1.1633681 ; Gorczyca, I., Plesiewicz, J., Dmowski, L., Suski, T., Christensen, N. E., Svane, A., … Speck, J. S. (2008). Electronic structure and effective masses of InN under pressure. Journal of Applied Physics, 104(1), 013704. ...

We report a detail theoretical study of the electronic structure and phase stability of transition metal oxides MnO, FeO, CoO, and NiO in their paramagnetic cubic B1 structure by employing dynamical mean-field theory of correlated electrons combined with ab initio band-structure methods. Our calculations reveal that under pressure these materials exhibit a Mott insulator-metal transition (IMT) which is accompanied by a simultaneous collapse of local magnetic moments and lattice volume, implying a complex interplay between chemical bonding and electronic correlations. Moreover, our results for the transition pressure show a monotonous decrease from similar to 145 to 40 GPa, upon moving from MnO to CoO. In contrast to that, in NiO, magnetic collapse is found to occur at a remarkably higher pressure of similar to 429 GPa. We provide a unified picture of such a behavior and suggest that it is primarily a localized to itinerant moment behavior transition at the IMT that gives rise to magnetic collapse in transition metal oxides. ; Funding Agencies|Deutsche Forschungsgemeinschaft through Transregio [TRR 80]; Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST "MISIS" [K3-2016-027]; European Research Council [ERC-319286 QMAC]; Swiss National Science Foundation (NCCR MARVEL); Swedish Research Council (VR) [2015-04391]; Swedish Foundation for Strategic Research (SSF) [SRL 10-0026]; Knut and Alice Wallenberg Foundation [2014-2019]; Swedish Government Strategic Research Area Grant Swedish e-Science Research Centre (SeRC); Ministry of Education and Science of the Russian Federation [14.Y26.31.0005]

S ; 119081 119083 99 ; S ; S ; S ; Copyright (2011) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. We perform Raman-scattering measurements at high hydrostatic pressures on c-face and a-face InN layers to investigate the high-pressure behavior of the zone-center optical phonons of wurtzite InN. Linear pressure coefficients and mode Grneisen parameters are obtained, and the experimental results are compared with theoretical values obtained from ab initio lattice-dynamical calculations. Good agreement is found between the experimental and calculated results. © 2011 American Institute of Physics. Work supported by the Spanish MICINN (Projects MAT2010-16116, MAT2008-06873-C02-02, MAT2010-21270-C04-04, and CSD2007-00045), the Catalan Government (BE-DG 2009), and the Spanish Council for Research (PIE2009-CSIC). Ibanez, J.; Manjón Herrera, FJ.; Segura, A.; Oliva, R.; Cusco, R.; Vilaplana Cerda, RI.; Yamaguchi, T. (2011). High-pressure Raman scattering in wurtzite indium nitride. Applied Physics Letters. 99:119081-119083. https://doi.org/10.1063/1.3609327 Veal, T., McConville, C., & Schaff, W. (Eds.). (2009). Indium Nitride and Related Alloys. doi:10.1201/9781420078107 Gallinat, C. S., Koblmüller, G., Brown, J. S., Bernardis, S., Speck, J. S., Chern, G. D., … Wraback, M. (2006). In-polar InN grown by plasma-assisted molecular beam epitaxy. Applied Physics Letters, 89(3), 032109. doi:10.1063/1.2234274 Li, S. X., Wu, J., Haller, E. E., Walukiewicz, W., Shan, W., Lu, H., & Schaff, W. J. (2003). Hydrostatic pressure dependence of the fundamental bandgap of InN and In-rich group III nitride alloys. Applied Physics Letters, 83(24), 4963-4965. doi:10.1063/1.1633681 Gorczyca, I., Plesiewicz, J., Dmowski, L., Suski, T., Christensen, N. E., Svane, A., … Speck, J. S. (2008). Electronic structure and effective masses of InN under pressure. Journal of Applied Physics, 104(1), 013704. ...

Taiwan's higher education system enjoys a high level of participation and a reputation for quality in Asia, but it is facing increasing pressure caused by expansion, low birthrate, and human capital flight. Further, with the Cross-Strait relations going downhill, higher education cooperation and faculty and student mobility between China and Taiwan are severely affected. Under these unfavorable circumstances, the Taiwanese government needs more proactive policies for universities to maintain quality, expand, and further internationalize.

Produktion af energi fra vedvarende energikilder kan potentielt dække verdens energibehov. Elektricitet genereret fra vind- og solenergi vil høst sandsynlig blive udbredt væsentligt i fremtiden i den europæiske union. På grund af fluktuationer i vindhastighed og indstråling fra solen skaber dette et behov for at kunne lagre den producerede energi. Hydrogen produktion vha. elektrolyse er en af de mest lovende måder at gøre dette på. Alkaliske elektrolysatorer har gennem de sidste årtier vist sig pålidelige i storskala (op til 160 MW), men for at blive kommercielt interessante, og for samtidig at kunne konkurrere mod alternative metoder til hydrogenproduktion som naturgas-reformering, må produktions- og investeringsudgifterne reduceres. En reduktion af investeringsudgifterne kan opnås ved at hæve processtemperatur og -tryk, da dette vil resultere i: 1) produktion af tryksat hydrogen og oxygen, 2) forøget elektrisk effektivitet og 3) forøget strømtæthed, dvs. forøget produktionshastighed af hydrogen for et givent elektrolysecelleareal. Denne afhandling beskriver en række orienterende teknisk forsøg primært med henblik på at undersøge muligheden for at producere brint og ilt med en ny type alkalisk elektrolysecelle ved høje temperaturer og tryk. For at kunne udføre målinger under højt tryk og ved forhøjede temperaturer var det nødvendigt at opbygge et målesystem omkring en autoklave, der kunne tåle høje temperaturer op til 250 °C og tryk op til 95 bar samt yderst basiske betingelser. Baseret på et litteraturstudium med henblik på at identificere resistente materialer til disse betingelser blev Inconel 600 udvalgt blandt de metaller, som er tilgængelige for autoklavebyggeri. En forsøgsopstilling med høj temperatur og tryk blev bygget omkring en sådan autoklave, der ved forsøgsstart blot havde en atmosfære med én gassammensætning. En anden opstilling til automatiserede målinger ved høj temperatur og tryk blev bygget baseret på erfaringer fra den første opstilling. Ledningsevnen af vandig KOH ved forhøjede temperaturer og høje koncentrationer blev undersøgt ved hjælp af van der Pauw metoden i kombination med elektrokemisk impedansspektroskopi (EIS). Ledningsevneværdier så høje som 2, 7 S cm-1 med 35 vægt% KOH, 2, 9 S cm-1 med 45 vægt%, og 2, 8 S cm-1 med 55 vægt% koncentreret vandige opløsninger blev målt ved 200 °C. Ledningsevnen af immobiliseret KOH blev bestemt ved den samme fremgangsmåde i samme temperatur og koncentrationsområde. Ledningsevneværdier af immobiliserede vandige opløsninger så høje som 0, 67 S cm-1 med 35 vægt%, 0, 84 S cm-1 med 45 vægt%, og 0, 73 S cm-1 med 55 vægt% blev målt ved 200 °C. En ny type af alkaliske elektrolysecelle, der kan drives ved høj temperatur og tryk, er blevet udviklet. En elektrolyt bestående af vandigt kalium hydroxid immobiliseret i en porøs SrTiO3 struktur blev anvendt i disse celler. Elektrolyseceller med gasdiffusionselektroder baseret på metalskum og den immobiliserede elektrolyt blev demonstreret ved temperaturer op til 250 °C og 40 bar. Strømtætheder på 1, 1Acm-2 og 2, 3Acm-2 blev målt med en cellespænding på hhv. 1,5 V og 1,75 V uden brug af dyre ædelmetal-katalysatorer. En elektrisk effektivitet på næsten 99 % ved 1, 1Acm-2 og 85 % ved 2, 3Acm-2, kombineret med relativ lave produktionsomkostninger, kan sandsynligvis føre til både reduceret investerings- og driftsomkostninger ved produktion af hydrogen og oxygen. En af de fremstillede celler blev indledningsvis "langtidstests" i 350 timer. Under antagelse af at de udviklede celler vil blive opskaleret og succesfyldt testet i tusinder af timer, kan disse celler muligvis komme til at spille en vigtig rolle i fremtidens scenarier for energilagring. ; The production of energy from renewable sources has the possibility to fulfill the worldwide energy demand. Electricity generation from wind energy converters and photovoltaic systems will be implemented within the European Union to a large extent. The fluctuation of the wind speed and solar radiation raises the necessity to store the produced energy. Hydrogen production by water electrolysis is one of the most promising ways to do so. Alkaline electrolyzers have proven to operate reliable for decades on a large scale (up to 160 MW), but in order to become commercially attractive and compete against conventional technologies for hydrogen production, such as natural gas reforming, the production and investment costs have to be reduced. A reduction of the investment costs may be achieved by increasing the operational pressure and temperature of the electrolyzer, as this will result in: 1) production of pressurized hydrogen and oxygen, 2) improved electrical efficiencies and 3) increased current density, i.e. increased hydrogen production rate for a given electrolyser cell area. This thesis describes an exploratory technical study mainly in order to examine the possibility to produce hydrogen and oxygen with a new type of alkaline electrolysis cell at high temperatures and pressures. To perform measurements under high pressure and at elevated temperatures it was necessary to build a measurement system around an autoclave which could stand high temperatures up to 250 °C and pressures up to 200 bar as well as extremely caustic environments. Based on a literature study to identify resistant materials for these conditions, Inconel 600 was selected among the metals which are available for autoclave construction. An initial single atmosphere high temperature and pressure measurement setup was build comprising this autoclave. A second high temperature and pressure measurement setup was build based on experiences from the first setup in order to perform automatized measurements. The conductivity of aqueous KOH at elevated temperatures and high concentrations was investigated using the van der Pauw method in combination with electrochemical impedance spectroscopy (EIS). Conductivity values as high as 2.7 S cm-1 for 35 wt%, 2.9 S cm-1 for 45 wt%, and 2.8 S cm-1 for 55 wt% concentrated aqueous solutions were measured at 200 °C. The conductivity of immobilized KOH was determined by the same method in the same temperature and concentration range. Conductivity values as high as 0.67 S cm-1 for 35 wt%, 0.84 S cm-1 for 45 wt%, and 0.73 S cm-1 for 55 wt% concentrated immobilized aqueous solutions were determined at 200 °C. A new type of an alkaline electrolysis cell was developed in order to operate at high temperatures and pressures. Aqueous potassium hydroxide immobilized electrolyte in porous SrTiO3 was used in those cells. Electrolysis cells with metal foam based gas diffusion electrodes and the immobilized electrolyte were successfully demonstrated at temperatures up to 250 °C and 40 bar. Different electro-catalysts were tested in order to reduce the oxygen and hydrogen overpotentials. Current densities of 1.1 A cm-2 and 2.3 A cm-2 have been measured at a cell voltage of 1.5 V and 1.75 V, respectively, without using expensive noble metal catalysts. Electrical efficiencies of almost 99 % at 1.1 A cm-2 and 85 % at 2.3 A cm-2 combined with relatively small production costs may lead to both reduced investment and operating costs for hydrogen and oxygen production. One of the produced electrolysis cells was operated for 350 h. Based on the successful results a patent application covering this novel cell was filed. Based on the successful results a patent application covering this novel cell was filed. Assuming that the developed cells will be scaled up and successfully tested for some thousand hours, they may offer an important role in future energy storage scenarios.