A5009091416- Advanced Condensed Matter Physics
- Thermal Expansion and Ionic Conductivity
- Magnetic and transport properties of perovskites and related materials
- Organic Electronics and Photovoltaics
- Advanced Battery Materials and Technologies
- Solid-state spectroscopy and crystallography
- Multiferroics and related materials
- Iron-based superconductors research
- Rare-earth and actinide compounds
- Conducting polymers and applications
- Inorganic Chemistry and Materials
- High-pressure geophysics and materials
- Magnetism in coordination complexes
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Crystal Structures and Properties
- Nuclear materials and radiation effects
- Advanced Chemical Physics Studies
- Ferroelectric and Piezoelectric Materials
- Liquid Crystal Research Advancements
- Zeolite Catalysis and Synthesis
- Boron and Carbon Nanomaterials Research
- Physics of Superconductivity and Magnetism
- Organic and Molecular Conductors Research
- Metal-Organic Frameworks: Synthesis and Applications
Institut Laue-Langevin
2014-2024
BP (United Kingdom)
2017
The University of Sydney
2016-2017
University of Arkansas at Fayetteville
2012
Bhabha Atomic Research Centre
2012
University of Oxford
2011
Institut Langevin
2008-2009
University of Fribourg
2004-2006
University of Geneva
2005-2006
Jadavpur University
2005
Three series of conjugated microporous polymers (CMPs) were studied as photocatalysts for hydrogen production from water using a sacrificial hole scavenger. In all cases, dibenzo[b,d]thiophene sulfone outperformed their fluorene analogues. A porous network, S-CMP3, showed the highest evolution rates 6076 μmol h–1 g–1 (λ > 295 nm) and 3106 420 nm), with an external quantum efficiency 13.2% at nm. S-CMP3 outperforms its linear structural analogue, P35, whereas in other nonporous are superior...
Fast-ion conductors are critical to the development of solid-state batteries. The effects mechanochemical synthesis that lead increased ionic conductivity in an archetypical sodium-ion conductor Na3PS4 not fully understood. We present here a comprehensive analysis based on diffraction (Bragg and pair distribution function), spectroscopy (impedance, Raman, NMR INS), ab initio simulations aimed at elucidating synthesis-property relationships Na3PS4. consolidate previously reported...
The antiferromagnetic structures of the layered oxychalcogenides (Sr1−xBax)2CoO2Cu2S2 (0 ≤ x 1) have been determined by powder neutron diffraction. In these compounds Co2+ is coordinated four oxide ions in a square plane and two sulfide at apexes an extremely tetragonally elongated octahedron; polyhedra share vertexes. magnetic reflections present diffraction patterns can all cases be indexed using √2a × c expansion nuclear cell, nearest-neighbor moments couple antiferromagnetically within...
A quantum magnet, ${\mathrm{LiCuSbO}}_{4}$, with chains of edge-sharing spin-$\frac{1}{2}$ ${\mathrm{CuO}}_{6}$ octahedra is reported. While short-range order observed for $T<10\text{ }\text{ }\mathrm{K}$, no zero-field phase transition or spin freezing occurs down to 100 mK. Specific heat indicates a distinct high-field near the 12 T saturation field. Neutron scattering shows incommensurate correlations $q=(0.47\ifmmode\pm\else\textpm\fi{}0.01)\ensuremath{\pi}/a$ and places an upper limit...
Solid electrolytes are crucial for next-generation solid-state batteries, and Na3PS4 is one of the most promising Na+ conductors such applications, despite outstanding questions regarding its structural polymorphs. In this contribution, we present a detailed investigation evolution in structure dynamics over wide temperature range 30 < T 600 °C through combined experimental–computational analysis. Although Bragg diffraction experiments indicate second-order phase transition from tetragonal...
We have performed extensive ab initio calculations to investigate phonon dynamics and their possible role in superconductivity ${\text{BaFe}}_{2}{\text{As}}_{2}$ related systems. The are compared inelastic neutron scattering data that offer improved resolution over published [Mittal et al., Phys. Rev. B 78, 104514 (2008)], particular at low frequencies. Effects of structural phase transition full and/or partial relaxations, with without magnetic ordering, on the calculated vibrational...
Zn(CN)2 and Ni(CN)2 are known for exhibiting anomalous thermal expansion over a wide temperature range. The volume coefficient the cubic, three dimensionally connected material, Zn(CN)2, is negative ({\alpha}V = -51 x 10-6 K-1) while Ni(CN)2, tetragonal in two sheets ({\alpha}a=-7 K-1), but overall positive ({\alpha}V=48 K-1). We have measured dependence of phonon spectra these compounds analyzed them using ab-initio calculations. show large differences that cannot be explained by simple...
Nonstoichiometric Nd2NiO4+δ shows oxygen ion mobility already at room temperature and as such is a promising material in the field of solid state ionic conductors. The present work aims to understand impact overstoichiometry on lattice dynamics Nd2NiO4 framework correlate dynamic instabilities anionic temperature. We performed neutron time-of-flight spectroscopy experiments coupled with DFT-based molecular calculations phases Nd2NiO4.0, Nd2NiO4.10, Nd2NiO4.25. Specific signatures phonon...
Abstract Charge transport in organic semiconductors is notoriously extremely sensitive to the presence of disorder, both internal and external (i.e., related interactions with dielectric layer), especially for n‐type materials. Internal dynamic disorder stems from large thermal fluctuations intermolecular transfer integrals (molecular) site energies weakly interacting van der Waals solids sources transient localization charge carriers. The molecular vibrations that drive typically operate at...
Metal (4f)-ligand (Cl 3p) bonding in LnCl(6)(3-) (Ln = Ce to Yb) complexes has been studied on the basis of 4f-->4f and Cl,3p-->4f charge-transfer spectra analysis these within valence bond configuration interaction model show that mixing Cl 3p into Ln 4f ligand field orbitals does not exceed 1%. Contrary this, Kohn-Sham formalism density functional theory using currently available approximations exchange-correlation tends strongly overestimate 4f-3p covalency, yielding, for YbCl(6)(3-), a...
Future applications of discotic liquid crystals (DLCs) in electronic devices depend on a marked improvement their conductivity properties. We present study 2,3,6,7,10,11-hexakishexyloxytriphenylene (HAT6) and show how local conformation, structural defects, thermal motions the picosecond time scale strongly affect efficient charge transport DLCs. A direct successful comparison classical molecular dynamics (MD) simulations with both neutron powder diffraction quasielastic scattering (QENS)...
The ${\text{Cu}}_{4}{\text{OCl}}_{6}{\text{daca}}_{4}$ system composed of isolated ${\text{Cu}}^{2+}\text{ }\text{S}=1/2$ tetrahedra with antiferromagnetic exchange should exhibit the properties a frustrated quantum spin system. Ab initio density functional theory calculations for electronic structure and molecular dynamics computations suggest complex interplay between magnetic exchange, electron delocalization, vibrations. Yet, extensive experimental characterization by means synchrotron...
$\mathrm{ZnNi}{(\mathrm{CN})}_{4}$ is a three-dimensional (3D) framework material consisting of two interpenetrating PtS-type networks in which tetrahedral $[\mathrm{Zn}{\mathrm{N}}_{4}]$ units are linked by square-planar $[\mathrm{Ni}{\mathrm{C}}_{4}]$ units. Both the parent compounds, cubic $\mathrm{Zn}{(\mathrm{CN})}_{2}$ and layered $\mathrm{Ni}{(\mathrm{CN})}_{2}$, known to exhibit 3D 2D negative thermal expansion (NTE), respectively. Temperature-dependent inelastic neutron scattering...
Quasielastic neutron scattering (QENS), underpinned by ab initio molecular dynamics (AIMD) simulations, has been used to directly observe oxide ion in solid electrolyte La2Mo2O9 on the nanosecond timescale, longest timescale probed conductors date. QENS gives activation energy of 0.61(5) eV for this process, while AIMD simulations reveal that exchange processes, which ultimately lead long-range diffusion La2Mo2O9, rely flexibility coordination environment around Mo6+, with ions jumps...
The dynamics of conjugated polymers are known to influence the performance optoelectronic devices. Polyalkylthiophenes a widely studied class polymers, which exhibit glass transition around room temperature and consequently sensitive variations. We two polyalkylthiophenes different side chain lengths (hexyl octyl) as function temperature, by comparing their quasi-elastic neutron scattering (QENS) with molecular simulations (MD). found good agreement between simulated experimental data within...
The optoelectronic properties of blends conjugated polymers and small molecules are likely to be affected by the molecular dynamics active layer components. We study regioregular poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) using (MD) simulation on time scales up 50 ns in a temperature range 250–360 K. First, we compare MD results with quasi-elastic neutron-scattering (QENS) measurements. Experiment give evidence vitrification P3HT upon blending plasticization...
Sodium niobate (NaNbO3) exhibits most complex sequence of structural phase transitions in perovskite family and therefore provides as excellent model system for understanding the mechanism transitions. We report temperature dependence inelastic neutron scattering measurements phonon densities states sodium niobate. The are carried out various crystallographic phases this material at temperatures from 300 K to 1048 K. spectra exhibit peaks centered around 19, 37, 51, 70 105 meV....
We have investigated temperature dependence of the lattice parameters and unit cell volume ZnF2 by neutron diffraction discovered negative thermal expansion (NTE) at low temperature. To understand why this simple compound exhibits NTE we performed first principle calculations. These calculations reproduce qualitatively experimental volume.
Discotic liquid crystalline (DLC) charge transfer (CT) complexes, which combine visible light absorption with rapid characteristics within the CT complex, can have a great potential for photovoltaic applications when they be made to self-assemble in bulk heterojunction arrangement separate channels electron and hole conduction. However, morphology of some complexes has been under debate many years. In particular, complex built from acceptor 2,4,7-trinitro-9-fluorenone (TNF) discotic...
Magnesium phosphate ceramics are a class of acid–base cements for bioengineering and civil engineering applications. We report on quasielastic neutron scattering results focusing the evolution state water in system during setting reaction, to shed light reaction mechanisms nature products. In first few minutes, consistent fraction molecules appears as immobile, after transient time, they start be progressively bound into product. The kinetics this last process has been described with an...