Author: Alexandra Friedrich

Pressure-Induced Polymerization of Polycyclic Arene-Perfluoroarene Cocrystals: Single Crystal X-ray Diffraction Studies, Reaction Kinetics, and Desig…

2020

Pressure-induced polymerization of aromatic compounds leads to novel materials containing sp3 carbon-bonded networks. The choice of the molecular species and the control of their arrangement in the crystal structures via intermolecular interactions, such as the arene–perfluoroarene interaction, can enable the design of target polymers. We have investigated the crystal structure compression and pressure-induced polymerization reaction kinetics of two polycyclic 1:1 arene–perfluoroarene cocrystals, naphthalene/octafluoronaphthalene (NOFN) and anthracene/octafluoronaphthalene (AOFN), up to 25 and 30 GPa, respectively, using single-crystal synchrotron X-ray diffraction, infrared spectroscopy, a…

chemistry.chemical_classificationAnthraceneStackingInfrared spectroscopyGeneral ChemistryPolymerCrystal structure010402 general chemistry01 natural sciencesBiochemistryCatalysis0104 chemical scienceschemistry.chemical_compoundCrystallographyColloid and Surface ChemistryPressure-induced polymerization; single-crystal synchrotron X-ray diffraction; high-pressure kinetic studychemistryPolymerizationX-ray crystallographySingle crystal

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Optical and structural study of the pressure-induced phase transition of CdWO$_4$

2017

Physical review / B 95(17), 174105 (2017). doi:10.1103/PhysRevB.95.174105

Phase transitionMaterials scienceBand gapchemistry.chemical_elementFOS: Physical sciences02 engineering and technologyCrystal structureTungsten01 natural sciences530symbols.namesakeCondensed Matter::Materials ScienceAb initio quantum chemistry methods0103 physical sciencesddc:530010306 general physicsBulk modulusCondensed Matter - Materials ScienceCondensed matter physicsMaterials Science (cond-mat.mtrl-sci)021001 nanoscience & nanotechnologychemistrysymbolsDirect and indirect band gaps0210 nano-technologyRaman spectroscopyAlta presiónTransición de fase

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Phase Stability of Lanthanum Orthovanadate at High Pressure

2016

The journal of physical chemistry / C 120(25), 13749 - 13762(2016). doi:10.1021/acs.jpcc.6b04782

Phase transitionAtomsPhononFOS: Physical scienceschemistry.chemical_elementCrystal atomic structure02 engineering and technologyCrystal structure010402 general chemistry01 natural sciencesMolecular physicssymbols.namesakeCondensed Matter::Materials ScienceAb initio quantum chemistry methodsPhase (matter)Physics - Chemical PhysicsLanthanumPhysical and Theoretical ChemistryAtoms; Calculations; Crystal atomic structureChemical Physics (physics.chem-ph)Condensed Matter - Materials ScienceChemistryMaterials Science (cond-mat.mtrl-sci)021001 nanoscience & nanotechnology5400104 chemical sciencesSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsCrystallographyGeneral Energyddc:540symbols0210 nano-technologyRaman spectroscopyCalculationsMonoclinic crystal system

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High-pressure phase ofLaPO4studied by x-ray diffraction and second harmonic generation

2016

The pressure-induced phase transition of monazite-type ${\mathrm{LaPO}}_{4}$ at $\ensuremath{\approx}26$ GPa is studied by single-crystal x-ray diffraction and second harmonic generation (SHG) up to 31 GPa. The structure of the postmonazite phase of ${\mathrm{LaPO}}_{4}$ has been obtained and it is shown that it corresponds to a post-barite-type structure with an acentric space group $P{2}_{1}{2}_{1}{2}_{1}$. A strong increase of the SHG signal at the transition confirms that the high-pressure polymorph is noncentrosymmetric. The phase transition involves a significant discontinuous decrease of the unit-cell volume by 6%, which is mainly due to a strong contraction of the $a$ lattice parame…

DiffractionPhase transitionMaterials scienceEnthalpy02 engineering and technology010402 general chemistry021001 nanoscience & nanotechnology01 natural sciences0104 chemical sciencesCrystallographyLattice constantPhase (matter)Acentric factorX-ray crystallographyddc:530Surface second harmonic generation0210 nano-technologyPhysical Review B

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Structure Solution of the High-Pressure Phase of CuWO4 and Evolution of the Jahn–Teller Distortion

2011

In this work, we have investigated the structural behavior of cuproscheelite up to 33.9 GPa by means of high-pressure single-crystal X-ray diffraction (SXRD) and extended X-ray absorption fine structure (EXAFS). According to EXAFS, beyond 9 GPa a phase transition takes place. On the basis of SXRD, the transition is from the triclinic (P1) structure to a monoclinic (P2/c) structure isotypic to wolframite. The transition implies abrupt changes of CuO6 and WO6 octahedra, but no coordination change. Further, we report the role played by the Jahn–Teller distortion of the CuO6 octahedra on the mechanism of the phase transition as well as the changes in the behavior of the Cu–O bonds for the tricl…

Phase transitionCrystallographyOctahedronExtended X-ray absorption fine structureChemistryGeneral Chemical EngineeringJahn–Teller effectPhase (matter)X-ray crystallographyMaterials ChemistryGeneral ChemistryTriclinic crystal systemMonoclinic crystal systemChemistry of Materials

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High-pressure Raman spectroscopy and lattice-dynamics calculations on scintillating MgWO4: Comparison with isomorphic compounds

2011

Research was financed by the Spanish Ministerio de Educacion y Ciencia (MEC) under Grants No. MAT2010-21270-C04-01/02/04, and No. CSD-2007-00045. J. R.-F. thanks the MEC for support through the FPI program, as well as the SPP1236 central facility in Frankfurt for its use. F. J. M. acknowledges support from Vicerrectorado de Investigacion y Desarrollo de la Universitat Politecnica de Valencia (UPV) (Grant No. UPV2010-0096). A. M. and P. R.-H. acknowledge the supercomputer time provided by the Red Espanola de Supercomputacion. A. F. appreciates support from the German Research Foundation (Grant No. FR2491/2-1).

Lattice dynamicsPhysicsHigh pressureCondensed Matter PhysicsHumanitiesElectronic Optical and Magnetic MaterialsPhysical Review B

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High-pressure structural phase transition inMnWO4

2015

The pressure-induced phase transition of the multiferroic manganese tungstate MnWO4 is studied on single crystals using synchrotron x-ray diffraction and Raman spectroscopy. We observe the monoclinic P2/c to triclinic P (1) over bar phase transition at 20.1 GPa and get insight on the phase transition mechanism from the appearance of tilted triclinic domains. Selective Raman spectroscopy experiments with single crystals have shown that the onset of the phase transition occurs 5 GPa below the previously reported pressure obtained from experiments performed with powder samples.

DiffractionPhase transitionMaterials scienceTungstatesCrystal structureTriclinic crystal systemCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsCondensed Matter::Materials ScienceCrystallographychemistry.chemical_compoundsymbols.namesakeCrystal-structureTungstatechemistryFISICA APLICADAsymbolsCondensed Matter::Strongly Correlated ElectronsMultiferroicsRaman spectroscopyDiffractionMonoclinic crystal systemPhysical Review B

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High-pressure phase of LaPO$_{4}$ studied by x-ray diffraction and second harmonic generation

2016

Physical review / B 94(13), 134109 (2016). doi:10.1103/PhysRevB.94.134109

530

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