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Article
Open AccessChemical expansion of CeO2−δ and Ce0.8Zr0.2O2−δ thin films determined by laser Doppler vibrometry at high temperatures and different oxygen partial pressures
The chemical expansion of ceria (CeO2−δ) and ceria-zirconia (Ce0.8Zr0.2O2−δ, CZO80) thin films is investigated by high-temperature laser Doppler vibrometry (LDV) at temperatures from 600 to 950 °C. The films are ...
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Article
Open AccessComparison of the electrical conductivity of bulk and film Ce1–xZrxO2–δ in oxygen-depleted atmospheres at high temperatures
Featuring high levels of achievable oxygen non-stoichiometry δ, Ce1−xZrxO2−δ solid solutions (CZO) are crucial for application as oxygen storage materials in, for example, automotive three-way catalytic converter...
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Article
Epitaxial Piezoelectric Langasite Thin Films for High-Temperature Application
The homo- and heteroepitaxial deposition of LGS (langasite, La3Ga5SiO14) thin films on LGS single crystals, Si and SiO2 substrates by pulsed laser deposition (PLD) is demonstrated. PLD is performed at substrate t...
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Article
Open AccessTransport and Electromechanical Properties of Ca3TaGa3Si2O14 Piezoelectric Crystals at Extreme Temperatures
Transport mechanisms in structurally ordered piezoelectric Ca3TaGa3Si2O14 (CTGS) single crystals are studied in the temperature range of 1000-1300 °C by application of the isotope 18O as a tracer and subsequent a...
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Article
Guest editorial: map interaction
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Article
Langasite-Type Resonant Sensors for Harsh Environments
Operation of single crystalline Ca3TaGa3Si2O14 (CTGS) and La3Ga5SiO14 (LGS) bulk acoustic wave resonators is demonstrated up to 1270 °C and 1470 °C, respectively. The mass sensitivity of such devices is about 35 ...
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Article
Thermal Stability of Materials for Thin-Film Electrochemical Cells Investigated by Thin-Film Calorimetry
Phase transformation enthalpies are determined using the recently developed measurement technique Thin-Film Calorimetry (TFC), which is based on piezoelectric resonators vibrating in thickness shear mode. They...
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Chapter
Bridging the Gap Between Field- and Lab-Based User Studies for Location-Based Services
There is a long-running debate about how to best evaluate mobile location-based services with users: in the lab or in the field? In this paper, we investigate how to combine benefits of both methods using an I...
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Article
High-Temperature Electromechanical Properties of CTGS
CTGS (Ca3TaGa3Si2O14) is a commercially available, Czochralski-grown piezoelectric material from the langasite family that has an ordered crystal structure. It can be excited piezoelectrically up to at least 1285...
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Chapter
High-Temperature Gas Sensors
High-temperature processes in the field of, e.g., energy conversion or chemical technologies require sophisticated process monitoring and control to ensure high-efficiency, low pollutant emissions, and safe op...
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Article
High-temperature thin-film calorimetry: a newly developed method applied to lithium ion battery materials
A thin-film calorimeter has been developed to investigate the thermodynamic properties of thin films including battery layer sequences. A new approach, i.e., the application of high-temperature stable piezoele...
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Article
Surface Acoustic Wave Devices: Materials Stability in Harsh Environments
The availability of high-temperature stable surface acoustic wave (SAW) devices would enable realization of wireless sensors for monitoring high-temperature processes. One of the most promising substrate mater...
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Article
Electronic and Ionic Transport Mechanisms of Stoichiometric Lithium Niobate at High-Temperatures
The electrical and electromechanical properties of lithium niobate single crystals are investigated at high-temperatures. The total electrical conductivity is determined as a function of temperature by impedan...
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Article
Synthesis of Different Molybdenum Disulfide Nanostructures and their Applicability in Lithium Ion Batteries with Ionic Liquid Electrolytes
Molybdenum disulfide (MoS2) nanostructures with three different morphologies are synthesized and tested with respect to their applicability in lithium ion batteries. Thereby, electrolytes based on ionic liquids a...
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Article
Thin Film Calorimetry - Device Development and Application to Lithium Ion Battery Materials
The work takes advantage of a newly developed measurement system which enables to investigate the thermodynamic properties of thin films including battery layer sequences. This technique, Thin-Film Calorimetry...
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Chapter and Conference Paper
Transitional Spaces: Between Indoor and Outdoor Spaces
Traditionally, spaces have been classified as being located either indoors or outdoors. On closer inspection, however, this distinction is not as clear cut as usually assumed. For example, when navigating comp...
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Article
High-temperature piezoelectric crystals and devices
Conventional piezoelectric materials such as quartz are widely used as high precision transducers and sensors based on bulk acoustic waves. However, their operation temperature is limited by the intrinsic mate...
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Article
Film Conductivity Controlled Variation of the Amplitude Distribution of High-temperature Resonators
High-temperature measurements of the spatial distribution of the displacement characteristics of a thickness shear mode langasite (La3Ga5SiO14) resonator are obtained using a laser Doppler interferometer. Thereby...
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Article
Micromachined Active Piezoelectric Structures for Applications above 600 °C
Miniaturized monolithic langasite structures are micromachined using local do** of lan-gasite and wet chemical etching. The diffusion coefficients of niobium, strontium and praseodymium in langasite are dete...
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Article
Electromechanical properties and defect chemistry of high-temperature piezoelectric materials
Langasite and gallium phosphate are shown to exhibit piezoelectrically stimulated bulk acoustic waves up to at least 1,400 and 900 °C, respectively. Most critical issues are stoichiometry changes due to, e.g. ...
