A5087554651- Ferroelectric and Piezoelectric Materials
- Photorefractive and Nonlinear Optics
- ZnO doping and properties
- Advanced Battery Materials and Technologies
- Advancements in Battery Materials
- Microwave Dielectric Ceramics Synthesis
- Luminescence Properties of Advanced Materials
- Ga2O3 and related materials
- Acoustic Wave Resonator Technologies
- Electronic and Structural Properties of Oxides
- Solid State Laser Technologies
- Glass properties and applications
- High-pressure geophysics and materials
- Nuclear materials and radiation effects
- Photonic and Optical Devices
- Semiconductor materials and devices
- Gas Sensing Nanomaterials and Sensors
- Crystal Structures and Properties
- Advanced Photocatalysis Techniques
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Metallurgical Processes and Thermodynamics
- Advanced Battery Technologies Research
- Solidification and crystal growth phenomena
- Solid-state spectroscopy and crystallography
Leibniz Institute for Crystal Growth
2016-2025
Forschungsverbund Berlin
2024
Austrian Centre for Electron Microscopy and Nanoanalysis
2023
Graz University of Technology
2023
University of Göttingen
2009
Technische Universität Braunschweig
2009
GFZ Helmholtz Centre for Geosciences
2009
Karlsruhe Institute of Technology
2009
Information Technology Institute
2007
Abstract Transparent semiconducting β‐Ga 2 O 3 single crystals were grown by the Czochralski method from an iridium crucible under a dynamic protective atmosphere to control partial pressures of volatile species Ga . Thermodynamic calculations on different atmospheres containing CO , Ar and reveal that growth combined with overpressure significantly decreases evaporation without any harm crucible. It has been found besides providing high oxygen concentration at temperatures, is also acting...
We present a new approach for scaling-up the growth of β-Ga2O3 single crystals grown from melt by Czochralski method, which has also direct application to other melt-growth techniques involving noble metal crucible. Experimental and theoretical results point thermodynamics as crucial factor in increasing volume growing crystal. In particular, formation metallic gallium liquid phase large volumes causes problems with crystal eutectic or intermetallic The larger be higher oxygen concentration...
The critical current density in symmetrical Li metal cells using Li<sub>7</sub>La<sub>3</sub>Zr<sub>2</sub>O<sub>12</sub> single crystals is determined. upper limit at room temperature without applying any external forces below 300 μA cm<sup>−2</sup>.
Truly bulk ZnGa2O4 single crystals were obtained directly from the melt. High melting point of 1900 ± 20 °C and highly incongruent evaporation Zn- Ga-containing species impose restrictions on growth conditions. The are characterized by a stoichiometric or near-stoichiometric composition with normal spinel structure at room temperature narrow full width half maximum rocking curve 400 peak (100)-oriented samples 23 arcsec. is crystalline phase Ga/Zn atomic ratio up to about 2.17. Melt-grown...
Transmission electron microscopes use electrons with wavelengths of a few picometers, potentially capable imaging individual atoms in solids at resolution ultimately set by the intrinsic size an atom. Unfortunately, due to imperfections lenses and multiple scattering sample, image reached is 3 10 times worse. Here, inversely solving problem overcoming aberrations probe using ptychography recover linear phase response thick samples, we demonstrate instrumental blurring under 20 picometers....
Two inch diameter, highly conducting (Si-doped) bulk β-Ga2O3 single crystals with the cylinder length up to one were grown by Czochralski method. The obtained revealed high structural quality characterized narrow x-ray rocking curves (FWHM ≤ 25 arc sec) and surface smoothness (RMS &lt; 200 pm) of epi-ready wafers. free electron concentration Hall mobility at room temperature in range 1.6–9 × 1018 cm−3 118 – 52 cm2 V−1 s−1, respectively, which are not affected a heat treatment...
Understanding the cause of lithium dendrites formation and propagation is essential for developing practical all-solid-state batteries. Li are associated with mechanical stress accumulation can cell failure at current densities below threshold suggested by industry research (i.e., >5 mA/cm2). Here, we apply a MHz-pulse-current protocol to circumvent low-current metal cells operating up density 6.5 mA/cm2. Additionally, propose mechanistic analysis experimental results prove that activity...
The temperature and oxygen partial pressure (pO2) dependent electrical conductivity of LiNbO3, LiTaO3, LiNb1-xTaxO3 (LNT) solid solutions up to 900 °C is presented. found be isotropic about 700 °C. Different Nb/Ta ratios do not affect activation energies at temperatures below 600 °C, which suggests an identical conduction mechanism, namely the migration Li ions by means vacancies. Above this temperature, noticeable deviations in Nb rich samples emerge due strongly increasing electronic...
Achieving efficient spatial modulation of phonon transmission is an essential step on the path to phononic circuits using "phonon currents". With their intrinsic and reconfigurable interfaces, domain walls (DWs), ferroelectrics are alluring candidates be harnessed as dynamic heat modulators. This paper reports thermal conductivity single-crystal PbTiO3 thin films over a wide variety epitaxial-strain-engineered ferroelectric configurations. The transport proved strongly affected by density...
Antiferroelectric materials have seen a resurgence of interest because proposed applications in number energy-efficient technologies. Unfortunately, relatively few families antiferroelectric been identified, precluding many applications. Here, we propose design strategy for the construction using interfacial electrostatic engineering. We begin with ferroelectric material one highest known bulk polarizations, BiFeO3. By confining thin layers BiFeO3 dielectric matrix, show that metastable...
We have systematically studied the growth, by Czochralski method, and basic physical properties of a 2 cm in. diameter bulk β-(AlxGa1−x)2O3 single crystal with [Al] = 0–35 mol. % in melt 5 steps. The segregation coefficient Al Ga2O3 1.1–1.2 results higher content crystals than melt. were also co-doped Si or Mg. 30 (33–36 crystals) seems to be limit for obtaining high structural quality suitable homoepitaxy. either semiconducting (no intentional co-dopants 0–30 Si-doped 15–20 %), degenerately...
Specific heat capacity measurements by differential scanning calorimetry (DSC) of single crystals solid solutions LiNbO3 and LiTaO3 are reported compared with corresponding ab initio calculations, the aim to investigate variation ferroelectric Curie temperature as a function composition. For this purpose, these were grown Czochralski pulling along c-axis. Elemental composition Nb Ta was investigated using XRF analysis, small samples homogeneous well known used for DSC measurements. We...
Attempts to grow terbium aluminium garnet (Tb3Al5O12, TAG) by the CZOCHRALSKI method lead crystals of millimeter scale. Larger could not be obtained. DTA measurements within binary system showed that TAG melts incongruently at 1840°C. The perovskite (TbAlO3, TAP) with a congruent melting point 1930°C is most stable phase in this system. region for primary crystallization TAP covers chemical composition and suppresses garnet.
Li7La3Zr2O12 (LLZO) garnet-type ceramics are considered as very promising candidates for solid electrolytes and have been extensively studied in the past few years. Several studies report on an increase ionic conductivity by doping with ions, such Al3+ Ga3+, to stabilize cubic modification of LLZO. Unfortunately, so far ion dynamics mainly using powdered samples. Such may suffer from chemical heterogeneities concerning Al distribution. Here, we took advantage Al-stabilized LLZO single...
Abstract The next‐generation of all‐solid‐state lithium batteries need ceramic electrolytes with very high ionic conductivities. At the same time a negligible electronic conductivity σ eon is required to eliminate self‐discharge in such systems. A non‐negligible may also promote unintentional formation Li dendrites, being currently one key issues hindering development long‐lasting batteries. This interplay suggested recently for garnet‐type 7 La 3 Zr 2 O 12 (LLZO). It is, however, well known...
Lithium niobate and lithium tantalate crystals are technologically important metal oxides with exceptional combinations of ferroelectric, piezoelectric, acoustic, optical, electrical properties. The self-diffusion both, the ionic constituents underlying point defects, is especially for overall conductivity. To get insight into their dynamics, we investigate in this work Li congruent ${\mathrm{LiNbO}}_{3}$ ${\mathrm{LiTaO}}_{3}$ single from different suppliers up to a temperature...
The ferroelectric to paraelectric phase transition in ${\mathrm{LiTaO}}_{3}$ and pure as well Mg-doped ${\mathrm{LiNbO}}_{3}$ is investigated theoretically by atomistic calculations the framework of density functional theory, experimentally calorimetry electrical conductivity measurements. First-principles models within stochastic self-consistent harmonic approximation (SSCHA) allow consider anharmonic effects thus obtain a realistic estimate Curie temperature ${T}_{C}$ both ferroelectrics....
Abstract SnO 2 is a semiconductor with wide optical bandgap (3.5 eV), which makes it an attractive transparent semiconducting oxide (TSO) for electronic and opto‐electronic applications. At elevated temperatures is, however, much more unstable than other TSOs (such as ZnO, Ga O 3 , or In ). This leads to rapid decomposition even under very high oxygen pressures. Our experiments showed that stoichiometric does not melt up 2100 °C, in contradiction earlier published data. Bulk single crystals,...