A5007123550- Ferroelectric and Piezoelectric Materials
- Acoustic Wave Resonator Technologies
- Electronic and Structural Properties of Oxides
- Solid-state spectroscopy and crystallography
- Gas Sensing Nanomaterials and Sensors
- Advanced Energy Technologies and Civil Engineering Innovations
- X-ray Diffraction in Crystallography
- Advanced Memory and Neural Computing
- Dielectric properties of ceramics
- GaN-based semiconductor devices and materials
- MXene and MAX Phase Materials
- Ferroelectric and Negative Capacitance Devices
- Advanced Chemical Physics Studies
- Bluetooth and Wireless Communication Technologies
- Ionic liquids properties and applications
- Machine Learning in Materials Science
- Nuclear Physics and Applications
- Advanced Sensor and Energy Harvesting Materials
- Semiconductor materials and devices
- Nuclear materials and radiation effects
- Earthquake Detection and Analysis
- Inorganic Chemistry and Materials
- Microwave and Dielectric Measurement Techniques
- Ga2O3 and related materials
- Quantum, superfluid, helium dynamics
NaMLab (Germany)
2020-2023
TU Bergakademie Freiberg
2014-2020
The precise quantification of the pyroelectric coefficient p is indispensable for characterization materials and development pyroelectric-based devices, such as radiation sensors or energy harvesters. A summary variety techniques to measure given in present review. It provides a classification after thermal excitation an outline capabilities drawbacks individual techniques. main selection criteria are: possibility separate different contributions coefficient, exclude thermally stimulated...
Ferroelectricity in hafnium oxide thin films is known to be induced by various doping elements and solid-solution with zirconia. While a wealth of studies focused on their basic ferroelectric properties memory applications, thorough the related pyroelectric application potential are only rarely found. This work investigates impact Si phase composition ferro- as well film capacitors. Dynamic hysteresis measurements field-free Sharp-Garn method were used correlate reported orthorhombic...
Abstract The generation of hydrogen as a chemical energy storage for power via fuel cells or the synthesis fuels has attained strong interest in recent years. By way example this is realized using electrolysis water with help excess electricity wind plants. However low temperature grade waste heat it could be found many industrial and household applications, there another source usable purpose. In first pragmatic experimentation we investigated pyroelectric effect ferroelectric BaTiO 3...
This work shows an alternative approach to extract the pyroelectric coefficient directly from response of crystal structure temperature variations. The uses parameters determined at different temperatures and Born effective charges calculated by density functional theory evaluate spontaneous polarization. On this basis, is using first derivative polarization with respect temperature. In work, we utilize laboratory single-crystal x-ray diffraction in a range 80 400 $\mathrm{K}$ demonstrate on...
Pure strontium titanate exhibits a cubic perovskite‐type structure at room temperature, but many approaches to break this high degree of symmetry are accessible. The present review summarizes some possible methods by discussing the effects stoichiometry variation, ion implantation, temperature treatment and external electric fields. Since oxygen vacancies most prominent mobile defect species in titanate, they play crucial role also for structural changes due influences. Possible...
The present study reports on the temperature dependent pyroelectric coefficient of free-standing and strain-free gallium nitride (GaN) grown by hydride vapor phase epitaxy (HVPE). Sharp-Garn method is applied to extract from electrical current response crystals subjected a sinusoidal excitation in range 0 °C 160 °C. To avoid compensation an internal conductivity, insulating GaN were used applying C, Mn, Fe doping during HVPE growth. different coefficients observed at room due correlate well...
Subjecting strontium titanate single crystals to an electric field in the order of 106 V m−1 is accompanied by a distortion cubic crystal structure, so that inversion symmetry vanishes and polar phase established. Since nature migration-induced field-stabilized (MFP) still unclear, present work investigates confirms pyroelectric structure. We measurements thermally stimulated currents reveal coefficient pMFP 30 μC K−1m−2. Therefore, dielectric transition originally centrosymmetric structure...
Pyroelectrocatalysis is the conversion of thermal energy directly into chemical energy. On background renewable energies and need for efficient industrial processes, waste heat hydrogen special relevance. Since reported thermodynamic cycles pyroelectric harvesting do not fit conditions encountered in a reactive medium such as water appropriately, we describe new charge-voltage-cycle characterised by fixed upper lower potentials. These threshold potentials comprise redox potential reaction...
The ferroelectric phase transition of copolymers vinylidene fluoride (VDF) with trifluoroethylene (TrFE) is well known and related to conformational changes in the polymer chain. Contrary expected paraelectric behaviour high temperature a pyroelectric investigation range from 0°C 130°C combined X-ray diffraction indicate copolymer as when prepared polarised high-temperature phase. Based on this finding orthorhombic space-group Fmm2 proposed for polar Above Curie material exhibits...
Many scientific questions require X-ray experiments conducted at varying temperatures, sometimes combined with the application of electric fields. Here, a customized sample chamber developed for beamlines P23 and P24 PETRA III DESY to suit these demands is presented. The body consists mainly standard vacuum parts housing heater/cooler assembly supplying temperature range 100 K 1250 an xyz manipulator holding contact needle measurements both high voltage low current. closed by exchangeable...
As defined by the IUCr, a material is crystal if it has essentially sharp diffraction pattern. Crystalline materials are wide spread in our today's life. More than 98 % of solid fraction earth comprises crystalline matter, most which oxides. Single-crystals particular basis for many applications – lasers, LEDs, sensors, etc. and play an important role fundamental research instance science. The discipline that elucidates impact structure on physical properties particularly crystallography...
Pyroelectric materials have a broad spectrum for practical application. Apart from the established infrared sensor technology, recently pyroelectric effect has been employed unconventionally in waste heat recovery, X-ray generation or water disinfection. This coupling phenomenon is temperature dependence of ferroelectric's spontaneous polarisation. A crystal structure that allows pyroelectricity cannot an inversion centre, if it had polar axis would not exist. Hence well-known perovskite...
Stoichiometric perovskite-type strontium titanate acts as an insulator because of its wide electronic band gap and has therefore great potential high-k dielectric storage material in memory applications. Degradation phenomena insulating properties transition metal oxides occur during long time voltage application. From the defect chemistry point view question arises how mobile species react on external electric field which impact redistribution stability crystal structure. Here, we discuss...
In non-centrosymmetric crystalline matter, marked by the pyroelectric effect, a change in temperature alters materials spontaneous polarization, which further changes charge density on material's surface. This results current flow trough an external circuit, differs drastically at boundary between two crystallographic phases. Therefore, offer great potential of low-temperature waste heat recovery utilizing e.g. Olsen-Cylce to convert residual into electric energy. A previous characterization...
According to Bhalla et al. the ABX3 perovskite system is single most versatile structure family regarding material properties.The wide range of functionalities realised through manifold combinations constituents for A-and B-site in structure.In confirmation and extension this abundance properties also real has a profound influence on material.Here, we discuss oxygen vacancy VO as dominating point defect aristotype strontium titanate SrTiO3 demonstrate how functionality can be by reversible...
spontaneous polarization in non-centrosymmetric crystals.
We report our investigations on HVPE grown GaN with thickness of 20 μm MOVPE GaN/Sapphire templates. The important characteristics for the proposed electric functionalities as drift layer in vertical devices power MOSFETs are surface morphology and doping concentration layer, which characterized by AFM CV measurements Schottky diodes, respectively. topography is sufficiently flat forming well-defined junctions following overgrowth. unintentional approaching a suitable low level enabling...