Search results for "Applied Physics"
showing 10 items of 1226 documents
Subamorphous thermal conductivity of crystalline half-Heusler superlattices
2021
The quest to improve the thermoelectric figure of merit has mainly followed the roadmap of lowering the thermal conductivity while keeping unaltered the power factor of the material. Ideally an electron-crystal phonon-glass system is desired. In this work, we report an extraordinary reduction of the cross-plane thermal conductivity in crystalline (TiNiSn):(HfNiSn) half-Heusler superlattices (SLs). We create SLs with thermal conductivities below the effective amorphous limit, which is kept in a large temperature range (120–300 K). We measured thermal conductivity at room temperature values as low as 0.75 W m−1 K−1, the lowest thermal conductivity value reported so far for half-Heusler compou…
Connections Between Topology and Macroscopic Mechanical Properties of Three-Dimensional Open-Pore Materials
2018
This work addresses a number of fundamental questions regarding the topological description of materials characterized by a highly porous three-dimensional structure with bending as the major deformation mechanism. Highly efficient finite-element beam models were used for generating data on the mechanical behavior of structures with different topologies, ranging from highly coordinated bcc to Gibson–Ashby structures. Random cutting enabled a continuous modification of average coordination numbers ranging from the maximum connectivity to the percolation-cluster transition of the 3D network. The computed macroscopic mechanical properties–Young's modulus, yield strength, and Poisson's ratio–co…
2D slab models of TiO2 nanotubes for simulation of water adsorption: Validation over a diameter range
2020
Financial support provided by Scientific Research Project for Students and Young Researchers Nr. SJZ/2019/2 realized at the Institute of Solid State Physics, University of Latvia is greatly acknowledged. Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under Grant Agreement No. 739508, project CAMART 2 .
Amorphous p-Type Conducting Zn-x Ir Oxide (x > 0.13) Thin Films Deposited by Reactive Magnetron Cosputtering
2021
Zinc-iridium oxide (Zn-Ir-O) thin films have been demonstrated as a p-type conducting material. However, the stability of p-type conductivity with respect to chemical composition or temperature is still unclear. In this study we discuss the local atomic structure and the electrical properties of Zn-Ir-O films in the large Ir concentration range. The films are deposited by reactive DC magnetron co-sputtering at two different substrate temperatures-without intentional heating and at 300 {\deg}C. Extended X-ray absorption fine structure (EXAFS) analysis reveals that strongly disordered ZnO4 tetrahedra are the main Zn complexes in Zn-Ir-O films with up to 67.4 at% Ir. As the Ir concentration in…
Nanocrystalline CaWO$_4$ and ZnWO$_4$ Tungstates for Hybrid Organic-Inorganic X-ray Detectors
2023
The experiment at the DESY PETRA-III synchrotron was performed within project No. I-20211105 EC at the Institute of Solid State Physics, University of Latvia, as the Cen ter of Excellence has received funding from the European Union’s Horizon 2020 Framework Pro gramme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.
Effects of particle clustering on the plastic deformation and damage initiation of particulate reinforced composite utilizing X-ray CT data and finit…
2018
In this paper, a new simulation technique which can include microstructural inhomogeneity of particulate reinforced composites is proposed to accurately study deformation pattern and damage mechanism in these composites. Three dimensional microstructures constructed from XCT images incorporated into finite element modeling codes with minimal approximation to capture the effects of cluster size, local volume fraction of particles in the cluster and the distance between clusters as relevant statistical quantities describing the microstructural inhomogeneity of particulate reinforced composites. A quantitative parameter as degree of clustering is defined to consider particle clustering effect.…
Nanoscale X-Ray Imaging of Spin Dynamics in Yttrium Iron Garnet
2019
Time-resolved scanning transmission x-ray microscopy (TR-STXM) has been used for the direct imaging of spin wave dynamics in thin film yttrium iron garnet (YIG) with spatial resolution in the sub 100 nm range. Application of this x-ray transmission technique to single crystalline garnet films was achieved by extracting a lamella (13x5x0.185 $\mathrm{\mu m^3}$) of liquid phase epitaxy grown YIG thin film out of a gadolinium gallium garnet substrate. Spin waves in the sample were measured along the Damon-Eshbach and backward volume directions of propagation at gigahertz frequencies and with wavelengths in a range between 100~nm and 10~$\mathrm{\mu}$m. The results were compared to theoretical …
Filtering and emission area identification in the Time Resolved Imaging data
2012
Abstract Time Resolved Imaging (TRI) acquisitions allow precise timing analysis of emission spots. Up to date technologies deeply challenge their isolation by hiding the weak ones, under sizing or over sizing visually detectable emission spots and finally by jeopardizing timing resolution. We report on an algorithm based on 1 and 2D signal processing tools which automates the identification of emission sites and optimizes separation between noise and useful signal, even for weak spots surrounding strong emission areas. The application of the algorithm on several sets of data from different types of devices and their results are also discussed.
Cluster matching in time resolved imaging for VLSI analysis
2014
International audience; If scaling has the benefit of enabling manufacturers to design tomorrow's integrated circuits, from the failure analyst point of view it also has the drawback of making devices more complex. The test sequence for modern VLSI can be quite long, with thousands of vector. Dynamic photon emission databases can contain millions of photons representing thousands of state changes in the region of interest. Finding a candidate location where to perform physical analysis is quite challenging, especially if the fault occurs on a single vector. In this paper, we suggest a new methodology to find single vector fault in dynamic photon emission database. The process is applied at …
Investigation of the SHS mechanisms of titanium nitride by in situ time-resolved diffraction and infrared thermography
2007
Abstract The self-propagating high-temperature synthesis (SHS) or combustion synthesis is a promising process to produce advanced ceramics due to the high purity of the elaborated materials and the very short synthesis time. Titanium nitride has been synthesised from pressed titanium powder and a nitrogen gas flow under a 0.1 MPa pressure. The influence of the addition of a TiN diluent was investigated. For the first time, SHS reaction mechanisms were determined from in situ time-resolved X-ray diffraction (TRXRD) experiments using the synchrotron radiation. These experiments were coupled with infrared thermography to study the propagation of the combustion reaction. It appeared that the in…