A5064009429- Hydrogen Storage and Materials
- Rare-earth and actinide compounds
- X-ray Diffraction in Crystallography
- Inorganic Chemistry and Materials
- Crystallization and Solubility Studies
- Boron and Carbon Nanomaterials Research
- Advanced Chemical Physics Studies
- Quasicrystal Structures and Properties
- High-pressure geophysics and materials
- Advanced Thermoelectric Materials and Devices
- Inorganic Fluorides and Related Compounds
- Semiconductor materials and interfaces
- MXene and MAX Phase Materials
- Superconductivity in MgB2 and Alloys
- Intermetallics and Advanced Alloy Properties
- Metallurgical and Alloy Processes
- Methane Hydrates and Related Phenomena
- Iron-based superconductors research
- Synthesis and characterization of novel inorganic/organometallic compounds
- Advanced Condensed Matter Physics
- Crystal Structures and Properties
- Mineralogy and Gemology Studies
- Ammonia Synthesis and Nitrogen Reduction
- Nuclear Materials and Properties
- Linguistic Education and Pedagogy
Stockholm University
2016-2025
Stockholm Environment Institute
2020
Technical University of Munich
2005-2013
Arizona State University
2006-2012
Tsinghua University
2012
University of Augsburg
2008
Augsburg University
2008
Los Alamos National Laboratory
2008
KTH Royal Institute of Technology
2004-2007
Rutherford Appleton Laboratory
2000-2007
The results of valence-only self-consistent field calculations on Hg n+ (n = 0, 1, 2) and HgH 1) using nonrelativistic quasirelativistic energy-adjusted ab initio pseudopotentials for are compared with corresponding all-electron values from (Hartree-Fock) relativistic (Dirac-Fock) atomic as well (Hartree-Fock no-pair Hamiltonian) molecular calculations. accuracy the pseudopotential scheme, e.g., reproduction major effects, is demonstrated both atom molecule. Correlation effects included in...
Two highly porous γ-aluminas, a commercial catalyst obtained from the calcination of boehmite and mesoporous product amorphous aluminum (oxy)hydroxide via sol–gel-based process were investigated by 27Al nuclear magnetic resonance (NMR), transmission electron microscopy (TEM), atomic pair distribution function (PDF) analysis synchrotron powder diffraction data. NMR data showed for both materials tetrahedrally octahedrally coordinated Al at 0.30:0.70 ratio, which is typical γ-aluminas. TEM...
Rare-earth elements containing aperiodic quasicrystals and their related periodic approximant crystals can exhibit nontrivial physical properties at low temperatures. Here, we investigate the 1/1 2/1 crystal phases of Ce-Au-Al system by studying ac susceptibility specific heat temperatures in magnetic fields up to 12 T. We find that these systems display signs quantum criticality similar observations other claimed critical systems, including Yb-Au-Al quasicrystal. In particular,...
β-Zn4Sb3 is an outstanding thermoelectric material mainly due to its extraordinarily low thermal conductivity, which similar that of glasses. Recently it was proposed interstitial Zn atoms are responsible for this peculiar behavior. Here we report on the crystal and electronic stucture low-temperature polymorph α-Zn4Sb3. During reversible phase transition intricate disorder in disappears, all localize completely. The structure α-Zn4Sb3 corresponds a narrow-gap semiconductor.
Structural competition in boron group elements has been studied by means of ab initio calculations. For we predict a structural change alpha-B-->alpha-Ga accompanied nonmetal-metal transition at pressure about 74 GPa. Al and Ga find an icosahedron based elemental modification (alpha-B) 0.22 0.05 eV/atom, respectively, higher energy than the corresponding metallic ground state structures. In particular, low difference for raises expectations into experimental feasibility new modifications...
We have investigated crystal structure, chemical bonding, and electronic properties of the compounds ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$, BiSe, ${\mathrm{Bi}}_{4}{\mathrm{Se}}_{3}$, ${\mathrm{Bi}}_{2}\mathrm{Se}$ by first-principles calculations within density functional theory. The are members a general series stacks ${({\mathrm{Bi}}_{2}{\mathrm{Se}}_{3})}_{m}{({\mathrm{Bi}}_{2})}_{n}$ composed five-layer blocks...
Structural stability and bonding properties of the hydrogen storage material Mg(2)NiH(4) (monoclinic, C2/c, Z = 8) were investigated compared to those Ba(2)PdH(4) (orthorhombic, Pnma, using ab initio density functional calculations. Both compounds belong family complex transition metal hydrides. Their crystal structures contain discrete tetrahedral 18 electron complexes T(0)H(4)(4-) (T Ni, Pd). However, situation in two systems was found be quite different. For Ba(2)PdH(4), electronic states...
The low-temperature phase transitions of thermoelectric Zn4Sb3 have been characterized using single-crystal X-ray diffraction, electrical resistance, and thermal conductivity measurements. Room-temperature stable, disordered β-Zn4Sb3 undergoes a transition at 254 K to ordered α-Zn4Sb3, which has an ideal composition Zn13Sb10. Below 235 K, second (α'-Zn4Sb3) can be detected. sequence β−α−α' is reversible. α−α' transformation originates from slight Zn deficiency with respect actual Zn13-δSb10.
The effects of high pressure (up to 9 GPa) on the thermal decomposition ammonia borane, BH3NH3, were studied in situ by Raman spectroscopy a diamond anvil cell. In contrast with three-step at ambient pressure, thermolysis under releases almost entire hydrogen content molecule two distinct steps. residual first is polymeric aminoborane, (BH2NH2)x, which also observed pressure. after second unique Presumably it corresponds precursor hexagonal BN where macromolecular fragments planar hexagon...
The intermetallic compound ZnSb is an interesting thermoelectric material largely due to its low lattice thermal conductivity. origin of the conductivity has so far been speculative. Using multitemperature single crystal x-ray diffraction (9--400 K) and powder (300--725 measurements, we characterized volume expansion evolution structural properties with temperature identified increasingly anharmonic behavior Zn atoms. From a combination Raman spectroscopy first principles calculations...
Layered zinc hydroxides (LZHs) with the general formula (Zn2+)x(OH–)2x−my(Am–)y·nH2O (Am– = Cl–, NO3–, ac–, SO42–, etc) are considered as useful precursors for fabrication of functional ZnO nanostructures. Here, we report synthesis and structure characterization hitherto unknown "binary" representative LZH compound family, Zn5(OH)10·2H2O, Am– OH–, x 5, y 2, n 2. Zn5(OH)10·2H2O was afforded quantitatively by pressurizing mixtures ε-Zn(OH)2 (wulfingite) water to 1–2 GPa applying slightly...
TiO2-II is a high pressure form of titania with density about 2% larger than that rutile. In contrast to the common polymorphs anatase, brookite and rutile its electronic structure optical properties are poorly characterized. Here we report on comparative electron-energy-loss-spectroscopy (EELS) study for which resolution valence-loss core-loss EELS data were acquired from nanocrystalline (<75 nm sized) particles an energy 0.2 eV. Electronic features revealed titanium L3,2 oxygen K...
Many forms of chemical bonding are exhibited by Al in intermetallic and Zintl phases. This is revealed the calculation electron localization function for series Al, CaAl 2 , SrAl BA1 4 Si Si. With this procedure it possible to distinguish clearly between metallic, covalent multicenter, homo‐ hetero‐nuclear single bonding.
This work presents a detailed, combined experimental and theoretical study on the structural stability of s−p bonded compounds with BaAl4 structure type (space group I4/mmm, Z = 2) as part broad program to investigate complex questions formation atomic arrangements in polar intermetallics. From ab initio calculations employing pseudopotentials plane wave basis set, we extracted optimized parameters, binding energies, electronic systems AeX(III)4, AeX(II)2X(IV)2, AeX(II)2X(III)2 (Ae Ca, Sr,...
We investigated crystal structure relationships, phase stability and chemical bonding of the thermoelectric materials ZnSb, alpha-Zn4Sb3, beta-Zn4Sb3 by means first principles calculations. The structures these are difficult to rationalise. This is especially true for because presence vacancies interstitial atoms. recognised rhomboid rings Zn2Sb2 as central structural building units present in all materials. Importantly, enable establish a clear relationship between disordered ordered...
The ternary intermetallic compounds $MAB=\text{CaAlSi}$, SrAlSi, BaAlSi, CaGaSi, SrGaSi, BaGaSi, SrAlGe, BaAlGe, CaGaGe, SrGaGe, BaGaGe, BaInGe, BaAlSn, CaGaSn, SrGaSn, and BaGaSn have been prepared by arc-melting stoichiometric elemental mixtures structurally characterized a combination of x-ray powder electron diffraction. They crystallize as variants the simple hexagonal ${\text{AlB}}_{2}$ structure type where trivalent tetravalent $A$- $B$-type atoms, respectively, form commonly planar...
The intermetallic compound ZnSb is an electron poor (II–V) semiconductor with interesting thermoelectric properties. Electrical resistivity, thermopower and thermal conductivity were measured on single crystalline various polycrystalline specimens. work establishes the presence of impurity band conduction as intrinsic phenomenon ZnSb. governs electrical transport properties at temperatures up to 300–400 K after which becomes conductor. Furthermore this inherently low lattice ZnSb, comparable...
Stishovite (SiO 2 with the rutile structure and octahedrally coordinated silicon) is an important high-pressure mineral. It has previously been considered to be essentially anhydrous. In this study, hydrothermal treatment of silica glass coesite at 350–550 °C near 10 GPa produces stishovite significant amounts H O in its structure. A combination methodologies (X-ray diffraction, thermal analysis, oxide melt solution calorimetry, secondary ion mass spectrometry, infrared nuclear magnetic...
Silicon has been regarded as a promising anode material for future lithium-ion batteries, and Li–Si phases play an important role. A detailed reinvestigation of the Li-rich part binary phase diagram revealed existence new phase, Li4.106(2)Si (Li16.42Si4). Li16.42Si4 forms through peritectic decomposition Li-richest Li17Si4 at 481–486 °C was characterized by single-crystal X-ray diffraction (a = 4.5246(2) Å, b 21.944(1) c 13.2001(6) space group Cmcm, Z 16), differential scanning calorimetry,...
Single crystals of Li17Si4 were synthesized from melts LixSi100–x (x > 85) at various temperatures and isolated by isothermal centrifugation. crystallizes in the space group F4̅3m (a = 18.7259(1) Å, Z 20). The highly air moisture sensitive compound is isotypic with Li17Sn4. represents a new thus lithium-richest phase binary system Li–Si superseding known Li21Si5 (Li16.8Si4). As previously shown Li22Si5 (Li17.6Si4) has been determined incorrectly. findings are supported theoretical...
Single crystals of Li15Si4 and Li15–xAlxSi4 (x = 0.63(1)) were obtained from equilibrated melts with compositions Li100–xSix 10, 15) Li83Al13Si4, respectively, isolated by isothermal centrifugation. Li14.37(1)Al0.63(1)Si4 crystallize the Cu15Si4 structure type (I4̅3d, ax=0 10.6322(9) Å, ax=0.63(1) 10.6172(4) Z 4, T 123 K). The incorporation Al equally affects both crystallographically distinguished Li positions in structure. replacement about 4% is firmly established refinement single...