A5071513664- Acoustic Wave Resonator Technologies
- Ferroelectric and Piezoelectric Materials
- Ultrasonics and Acoustic Wave Propagation
- Gas Sensing Nanomaterials and Sensors
- Photorefractive and Nonlinear Optics
- Advanced MEMS and NEMS Technologies
- Analytical Chemistry and Sensors
- Microwave Dielectric Ceramics Synthesis
- Electronic and Structural Properties of Oxides
- Advancements in Battery Materials
- Mechanical and Optical Resonators
- Advancements in Solid Oxide Fuel Cells
- Semiconductor materials and devices
- Advanced ceramic materials synthesis
- Optical and Acousto-Optic Technologies
- Advanced Battery Materials and Technologies
- Advanced Sensor Technologies Research
- Solid-state spectroscopy and crystallography
- Catalytic Processes in Materials Science
- Magnetic and transport properties of perovskites and related materials
- Advanced materials and composites
- Advanced Chemical Sensor Technologies
- Advanced Fiber Optic Sensors
- Advanced Battery Technologies Research
- Geographic Information Systems Studies
Clausthal University of Technology
2015-2024
Forschungszentrum Energiespeichertechnologien
2011-2024
Leibniz Institute for Solid State and Materials Research
2021
National Institute of Standards and Technology
2021
Lviv Polytechnic National University
2020
University of Münster
2011-2019
Massachusetts Institute of Technology
1998-2018
Institute of Physics
2017
Intelligent Transport Systems Niedersachsen
2014
Faculdades Guarulhos
2013
Abstract Climate change–driven shifts in streamflow timing have been documented for western North America and are expected to continue with increased warming. These changes will likely the greatest implications on already short overcommitted water supplies region. This study investigated American over 1948–2008 period, including very recent warm decade not previously considered, through (i) trends measures, (ii) two second-order linear models applied simultaneously region test acceleration...
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...
Langasite (La3Ga5SiO14) and related compounds are promising candidates for high-temperature piezoelectric applications. To determine the stable operation of langasite as a bulk acoustic wave (BAW) resonator, we characterized electrical conductivity [σel=1.56×exp(−1.07 eV/kT)S/cm] oxygen diffusivity [DoxT=5×10−5 exp(−1.45 eV/kT)cm2/s] up to elevated temperatures. was successfully operated 900 °C BAW resonator with an average mass sensitivity about 0.17 μg Hz−1 cm−2. This enables, in...
Piezoelectric crystals like langasite (La3Ga5SiO14, LGS) and gallium orthophosphate (GaPO4) exhibit piezoelectrically excited bulk acoustic waves at temperatures of up to least 1450 °C 900 °C, respectively. Consequently, resonant sensors based on those materials enable new sensing approaches. Thereby, high-temperature microbalances are particular interest. They correlate very small mass changes during film deposition onto resonators or gas composition-dependent stoichiometry thin films...
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 Different aspects of ferroelectric LiTaO 3 (LT) such as polaronic defects, optical response and electrical conductivity are investigated by the most recent theoretical experimental approaches. Comparing results with state-of-the-art knowledge widely studied LiNbO (LN), we evaluate general assumption that there is little difference between aforementioned properties LT LN. First-principles calculations reveal existence point defects in qualitatively compatible picture established...
Electrical conductivity and acoustic loss Q−1 of single crystalline Li(Nb,Ta)O3 solid solutions (LNT) are studied as a function temperature by means impedance spectroscopy resonant piezoelectric spectroscopy, respectively. For this purpose, bulk wave resonators with two different Nb/Ta ratios investigated. The obtained results compared to those previously reported for congruent LiNbO3. dependent electrical LNT LiNbO3 show similar behavior in air at high temperatures from 400 700 °C....
Hydrogen is an impurity that incorporated into LiNb1–xTaxO3 crystals during crystal growth or thermal treatment in a humid atmosphere and may influence the physical properties different ways. In this context, diffusion of hydrogen important process because it enhance ion conductivity material. We investigated LiNbO3, LiTaO3, LiNb0.15Ta0.85O3 single temperature range between 311 606 °C using deuterium from gaseous D2O source as tracer. Diffusivities were determined by analyzing relative...
The investigation of the structural phase transition in vicinity Curie temperature crystals is motivated by expected combination advantageous high‐temperature properties and , including high piezoelectric modules remarkable stability, respectively. marks ultimate limit for exploiting properties; however, transition‐related modifications might impact this other even below . Remarkably, from ferroelectric to paraelectric phase, whose strongly depends on composition x shows a significant drop...
Wireless surface acoustic wave devices based on langasite allow sensor operation in high-temperature environments. While shows piezoelectric behavior up to temperatures close its melting point of 1470 °C, the stability thin film electrodes for excitation waves limits application tem- perature. Different metal and ceramic films are tested regarding their applicability as electrode materials wireless at above 600 °C. The should with- stand 800 °C least several hours. platinum, platinum-...
Ferroelectric LiNb1-xTaxO3 solid solutions with various Nb/Ta ratio were grown from the melt by Czochralski method. The exact composition of crystals was determined inductively coupled plasma atomic mass spectrometry. dependence crystal on initial obtained and explained a wide separation between phase boundaries liquid phases LiNbO3-LiTaO3 diagram. Using high-resolution X-ray diffraction, parameters c unit cell (LiNb0.88Ta0.12O3: = 5.1574 Å 13.8498 Å). Further, Curie temperature TC measured...
High-temperature optical in situspectroscopy was used to investigate the defect absorption, redox kinetics, and chemical diffusion of a lithium deficient (48.4 mol% Li2O) congruent melting niobate single crystal (c-LN). Under reducing atmospheres various oxygen activities, aO2, UV-Vis-NIR spectra measured at 1000 °C are dominated by an absorption band due free small polarons centered about 0.93 eV. The polaron intensity found follow power law form with m = −1/4. A reduction model involving...
Among the class of ferroelectric crystals, lithium-niobate-tantalate (LiNb1-xTaxO3) system attracts growing attention for applications in field nonlinear optics, functional electronics and piezoelectrics. The self-diffusion ionic constituents, especially Li, is important overall electric conductivity. aim this investigation to figure out how Li diffusion lithium niobate-tantalate solid solution crystals behaves as a function Ta content. Specially grown LiNb1-xTaxO3 single with different...
An optical spectroscopy study is reported of single crystals the LiNbO 3 –LiTaO solid solution. The spectra are dominated by fundamental absorption edges. direct band‐to‐band transitions in congruent (LN) and LiTaO (LT) as well selected compositions solutions grown from mixtures congruently melting end members studied at temperatures up to 1200 °C. At room temperature, bandgaps LN LT assume values about 4.0 4.6 eV, respectively. With rising temperatures, edges found shift lower energies....