Characterization Of Solid Materials Research Articles

Solid materials characterization using split ring resonators enclosed by power divider

AbstractA highly sensitive microwave sensor for solid material characterization is proposed. A novel design consisting of split ring resonators (SRRs) within a three‐port power divider is developed. The three‐port junction is employed as the host to provide two output channels, and SRRs are loaded through electric coupling to the power divider as the sensing area. The SRRs are located symmetrically so that any change in the electric field of the SRRs is transferred equally to the transmission coefficients of the three‐port junction. The operation of the proposed sensor is based on the downshifting of the transmission zero caused by the loading of samples. The two identical outputs help to control cross‐sensitivity due to external effects. The performance of the fabricated prototype on a 22.2 × 18.8 × 1.6 mm3 printed circuit board is presented. It is shown that a 135 MHz shift per unit relative permittivity change can be achieved. The normalized sensitivity is found to be 3%, which is relatively higher than the sensors reported in the literature.

Three-dimensional measurement of laser-induced thermal mirror dynamics using photothermal vortex interferometer with azimuthal phase spectra analysis

Measurement of the thermal mirror caused by laser heating provides direct access to the optical, thermophysical, and mechanical properties of solid materials. However, the nanoscale time-dependent three-dimensional (3D) thermal mirror hinders the existing photothermal techniques to obtain the thermal mirror dynamics without sacrificing the spatial profile of the thermal mirror. To fill the gap of 3D measurement of laser-induced thermal mirror dynamics, a photothermal vortex interferometer (PTVI) is proposed. The PTVI produces a multi-ring petal-like interferogram by the coaxial coherent superposition of the high-order conjugated Laguerre-Gaussian beams. The nanoscale 3D thermal mirror with a rotationally symmetric surface profile can be encoded into different azimuthal phase shifts at the different radii of the interferogram. An azimuthal phase spectra analysis is proposed to extract the azimuthal phase shifts from the continuously captured interferograms, enabling reconstruction of the 3D thermal mirror dynamics. The experimental results verified that the PTVI can measure the surface deformation due to the thermal mirror at an accuracy of picometer scale, and the optical and thermophysical properties of an optical glass sample can be determined with the assistance of the thermophysical model of the 3D thermal mirror dynamics. The approach can be an effective tool for characterization of solid materials.

Integrated Microwave Sensor and Antenna Sensor Based on Dual T-Shaped Resonator Structures for Contact and Noncontact Characterization of Solid Material

This paper proposes the integration of microwave sensors (MS) and antenna sensors (AS) for contact and non-contact characterization of solid materials. Integration between MS and AS were determined based on the reflection coefficient (S11) where S11 of ≥ -10 dB was proposed as MS and S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> of ≤ -10 dB was proposed as AS. The proposed sensor consists of a dual T-Shaped resonator with single port operating at a resonant frequency of f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r1</sub> = 1.81 GHz for MS and f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r2</sub> = 2.34 GHz for AS using FR-4 substrate with ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> of 4.3, tan δ of 0.0265 and thickness of 1.6 mm. Furthermore, the two resonant frequencies had independent characteristics with different sensing hotspots. MS are proposed for permittivity detection of the Material Under Test (MUT) for contact detection while non-contact detection is proposed by utilizing AS. The procedure for contact detection was carried out by placing the material under test on the surface of the sensor while non-contact detection was carried out by placing the MUT with an air gap between the MUT (d) and the AS was 0.5 - 1.5 mm. The measurement results showed that the average accuracy was 99.30% and 99.31% for the MS and AS for the permittivity range of 1 - 6.15 while the normalized sensitivities of the proposed sensors were 1.15 % and 0.16%, respectively. The results of this research are novel and can be recommended for several purposes related to biomedical and pharmaceutical industries requiring contact and non-contact detection of material characterization.

A Dual-Scale CSRRs-Based Sensor for Dielectric Characterization of Solid Materials

A compact planar sensor is presented in this letter, which could measure the dielectric constants of solid materials at microwave and sub-THz frequencies, simultaneously. The lower band resonator is based on a complementary split ring resonator (CSRR), fed by a coplanar waveguide line on the board operating at 4.76 GHz, and the upper band sensor is a 3 × 3 CSRR array, excited by a pair of WR-10 open-ended waveguide probes operating at 112 GHz. The upper band CSRR array is nested in the lower band CSRR resonator, but their sensing functions are independent of each other. A coincident sensing area is obtained that needs a testing sample with small volume. Dielectric films composed of polydimethylsiloxane and barium-titanate with different volume fractions are used to verify the performance of the sensor in both frequency scales. The advantages of the proposed design, including compact size, high sensitivity, low sample volume, and dual-scale operation, make it a competitive solution for detecting solid materials with similar dielectric properties in a single frequency band, for application such as the food industry, material quality control, and biomedical.

Correlation of the Isotropic NMR Chemical Shift with Oxygen Coordination Distances in Periodic Solids

In Nuclear Magnetic Resonance (NMR) spectroscopy, the isotropic chemical shift δiso is a measure of the electron density around the observed nuclide. For characterization of solid materials and compounds, it is desirable to find correlations between δiso and structural parameters such as coordination numbers and distances to neighboring atoms. Correlations of good quality are easier to find when the coordination sphere is formed by only one element, as the electron density is obviously strongly dependent on the atomic number. The current study is therefore restricted to nuclides in pure oxygen coordination. It is shown that the isotropic shift δiso correlates well with the average oxygen distances (as defined by the coordination sphere) for the nuclides 23Na (with spin I=3/2), 27Al (I=5/2), and 43Ca (I=7/2), using literature data for a range of periodic solids. It has been previously suggested for 207Pb (I=1/2) that δiso may alternatively be related to the shortest oxygen distance in the structure, and our study corroborates this also for the nuclides considered here. While the correlation with the minimal distance is not always better, it has the advantage of being uniquely defined. In contrast, the average distance is strongly dependent on the designation of the oxygen coordination sphere, which may be contentious in some crystal structures.

A Career in Catalysis: Avelino Corma

As one of the most influential scientists in the field of heterogeneous catalysis and materials science, Prof. Avelino Corma has made significant contributions in many diverse fields, spanning over solid catalysts for petrochemistry, solid catalysts for production of fine chemicals, synthesis of microporous and mesoporous materials, development of inorganic–organic hybrid materials, supported metal catalysts (from isolated metal atoms to nanoclusters and nanoparticles) and photochemistry with solid materials. These experimental approaches are complemented with characterization of solid materials with advanced spectroscopy and microscopy techniques as well as theoretical calculations/modeling. The aim of this Account is to overview Avelino’s distinguished scientific career and highlight the most remarkable achievements made in his research activities during >40 years. We attempt to show the evolution of Avelino’s research topics in his group throughout his career and the approaches that Avelino has chosen to tackle the challenges encountered. The research paradigm developed by Avelino and his team can be inspiring to the researchers in the field of materials science who are striving to translate the knowledge generated in fundamental studies into practical applications for addressing the new scientific challenges encountered in building a sustainable world.

ELECTROCHEMISTRY OF IMMOBILIZED MICROPARTICLES AND MICRODROPLETE: ACCESS TO FUNDAMENTAL DATA OF SOLID MATERIALS AND IONS

The idea to study the electrochemistry of immobilized microparticles has been published by this author for the first time in 1989. In the last 32 years, this approach has been shown to be very successful not only for analytical characterization of solid materials, but also applicable to extract thermodynamic and kinetic data, and even to determine the age of metal specimen. In 2000, it has been shown that the electrochemistry of immobilized microdroplets gives an elegant access to determine the Gibbs free energies of ion transfer between immiscible solvents. These measurements are performed with a standard 3-electrode potentiostate and can be used also for solvents, which cannot be used in experiments with the classical 4-electrode technique.&#x0D; The electrochemistry of microparticles and microdroplets share several common features with respect to the electrode mechanisms: in both cases three-phase electrodes are realized and ion and electron transfer proceed simultaneously.&#x0D; This talk reviews the activities of the speaker and his cooperation partners during the last 3 decades paying special attention to those results, which are of general interest.

Design and Optimization of Interdigitated Microwave Sensor for Multidimensional Sensitive Characterization of Solid Materials

This paper presents an interdigital capacitor (IDC)-based high sensitivity microwave sensor for the multidimensional (complex permittivity and thickness) characterization of solid materials. The proposed sensor was implemented by etching a slot resonator with an IDC on the ground layer of 0.76 mm-thick RF-35 substrate with relative permittivity of 3.5 and loss tangent of 0.0018. The IDC fingers were configured as a spur-line structure to create an intense electric field zone that interacted significantly with the material under test (MUT), resulting in high sensitivity. A sensor prototype with optimized dimensions generated dual resonant frequencies of 2.35 GHz and 5.79 GHz and was used to measure the MUT’s complex permittivity and thickness, respectively. Experimental results revealed that the resonant frequencies of the developed sensor exhibited high sensitivities (276 MHz/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon _{r}$ </tex-math></inline-formula> for permittivity and 143 MHz/mm for thickness) and resolutions (0.27678 for permittivity and 0.1439 for thickness) of solid materials. Moreover, the sensing accuracies were 99.9% for real permittivity and 97.7% for imaginary permittivity. The demonstrated high performance of the developed sensor validates its applications in the multidimensional characterization of various solid materials.

Sulfur capture and release by ilmenite used as oxygen carrier in biomass combustor

Oxygen-Carrier-Aided Combustion (OCAC) is a promising technology for the combustion of solid heterogeneous fuels such as biomass and waste. However, a frequently encountered problem with biomass and waste is their high alkali contents, which can lead to the build-up of deposits on heat transfer surfaces, leading to corrosion and increased maintenance costs.The addition of elementary S is one of the options used in combustion processes to mitigate corrosion. Sulfation of KCl reduces the severity of corrosion on heat transfer surfaces due to the transformation of KCl into K2SO4, which is considered to be less corrosive. Even though many studies have been performed on the influence of sulfur on the corrosion process, there is to date little knowledge about the interaction of S with ilmenite used as an oxygen carrier (OC). Therefore, there is a need to understand the influence of S on both the properties of the ilmenite used as an OC and the morphologic development of the ilmenite particles. This study investigates the interactions between S and ilmenite as bed material, with the focus on the roles of ash layers in the capture and release of the added S under different combustion conditions.The present study focuses on bed material that was exposed in the Chalmers 12-MWth Circulating Fluidized Bed (CFB) combustor run with biomass as fuel and with the addition of elemental S. Calcined ilmenite without ash elements was used as a reference material and the collected bed material samples were tested for their abilities to capture S in a laboratory fluidized bed batch reactor run at 950 °C. Controlled SO2 exposures in an oxidizing environment were carried out, and the reversibility of the mechanisms for uptake and release of S was tested. Understanding the uptake and release of S components by ilmenite is of importance not only for the handling of bed materials, but also for developing new protocols for corrosion prevention in OCAC.In the present study, the ilmenite-sulfur interactions were followed using gas analysis, solid material characterization (SEM-EDX), and thermodynamic calculations (FactSage). The results suggest that SO2 is captured under oxidative conditions, preferentially by bed materials with developed ash layers, and released under reducing conditions. Mixed-sulfate-phase K2Ca2(SO4)3, K2SO4 and CaSO4 are found to be the main formed phases that can participate in S uptake and release.

Multi-band microwave sensor based on Hilbert’s fractal for dielectric solid material characterization

A planar sensor designed using the fourth Hilbert fractal curve iteration for solid material characterization at multiple frequencies is reported in this paper. The fractal curve is self-similar with space-filling properties. The Hilbert fractal geometry is used to form a compact resonator, with a multiband frequency response where miniaturization is achieved since a large transmission line length is effectively confined in a limited area. The sensor provides five resonances in the frequency range from 0 to 5 GHz. The resonant frequencies are 0.56, 1.68, 2.72, 3.69 and 4.72 GHz, all used to measure the real permittivity of known samples with a sensitivity of 7, 20, 27, 43 and 50 MHz/permittivity, respectively. The sensor is used to measure dielectric samples with 20 × 20 mm2 areas with several thicknesses. Simulations and measurements demonstrate that the Hilbert fractal geometry can be used to design a multiband planar sensor for solid dielectric material characterization.

High-Accuracy Complex Permittivity Characterization of Solid Materials Using Parallel Interdigital Capacitor- Based Planar Microwave Sensor

This paper presents a planar microwave sensor for the sensitive and accurate characterization of complex permittivity of solid materials. To realize the proposed sensor, the combination of a parallel interdigital capacitor and a dual wide gap resonator was etched on the ground plane and coupled with a transmission line in the top plane of a printed circuit board. The main advantage of the proposed sensor configuration lies in the generation of a high-intensity coupled resonating electric field suitable for the sensitive measurement of complex permittivity of solid materials. The high-intensity electric field enhances the coupling and field interaction, and thereby produces a high-accuracy permittivity characterization of a solid material exposed to the maximum field of the proposed sensor. Our developed microwave permittivity sensor, which characterized the complex permittivity of several materials by exploiting the measured shifts in resonance frequencies, exhibited a high sensitivity (up to 37% shift in resonance frequency for 20% change in permittivity) at least 1.5 times higher than previously reported microwave permittivity sensors. In addition, the proposed sensor exhibited 99.9% and 99.7% sensing accuracies for real and imaginary parts of permittivity, respectively, and the measurement results revealed an excellent (0.06758) and high sensitivity (67.58 MHz per unit change in real permittivity).

Application of TPO/TPR methods in oxidation investigations of CoSb3 and Mg2Si thermoelectrics with and without a protective coating of “black glass”

One of the main problems in thermoelectric material research is degradation of thermoelectric materials caused by oxidation at elevated temperatures in air. In order to prevent these materials from oxidation, they can be covered with protective coating. A good candidate for such coating is layers made of so-called black glass, which can be successfully applied as a protective coating against oxidation. Thermal oxidation study can be demanding for measuring equipment used for in situ examination due to formation of volatile species which are corrosive for both metal and ceramic elements. This focused our attention on temperature-programmed reduction—temperature-programmed oxidation TPR/TPO methods in which the risk of damage of expensive parts of the equipment can be minimized. These methods have an important place in characterization of solid materials and can be used as the thermal analysis methods providing complementary results to TG and DTA. The aim of the study was to confirm the usefulness of TPR/TPO methods for the study of oxidation of modern thermoelectric materials and validation of “black glass” coatings as surface protection. Pure and doped (In; Ce) CoSb3 as well as pure Mg2Si were chosen for this study. XRD and SEM/EDX methods were used for material characterization, and TG/DTA measurements were carried out as reference for TPR/TPO. We succeeded to deposit “black glass” coating on Mg2Si and to show suppression of oxidation up to 495 °C. Experimental results show high usability of the TPR/TPO method in oxidation studies of thermoelectrics and protective coatings of thermoelectric materials.

Phase-Transition Energies, New Characterization of Solid Materials and Anisotropy

Non-iterative analysis of indentation results allows for the detection of phase transitions under load and their transition energy. The closed algebraic equations have been deduced on the basis of the physically founded normal force depth3/2 relation. The precise transition onset position is obtained by linear regression of the FN = kh3/2 plot, where k is the penetration resistance, which also provides the axis cuts of both polymorphs of first order phase transitions. The phase changes can be endothermic or exothermic. They are normalized per μN or mN normal load. The analyses of indentation loading curves with self-similar diamond indenters are used as validity check of the loading curves, also from calibration standards that exhibit previously undetected phase-transitions and are thus incorrect. The phase-transition energies for fused quartz are determined from the loading curves from instrument provider handbooks. The anisotropic behavior of phase transition energies is studied for the first time. Quartz is a useful test object. The reasons for the packing-dependent differences are discussed on the basis of the local crystal structure under and around the inserting tip.

Highly sensitive coulometric titration of oxygen for the characterization of solid materials at elevated temperatures

Abstract. A new setup for characterization of solid material oxygen exchange and conductivity in a broad oxygen partial pressure range and at elevated temperatures is presented. The development target of this setup is directed towards the detection of ultra-low amounts of exchanged oxygen. For this, electrochemical cells made of yttria-stabilized zirconia (YSZ) were optimized and applied in a flow-through arrangement. The design and process measures enable a lower limit of detection below 100 pmol of exchanged oxygen. Furthermore, the system characteristics concerning oxygen dispersion, titration efficiency and electrode kinetics are described.

Propagation properties of interface waves at fluid-coated solid interface

The interface waves propagating along liquid-solid interface are widely studied and used in a lot of fields, especially in ocean acoustics, ocean engineering, and ocean geophysics. The dispersion characteristics of this kind of interface wave are closely related to the seafloor medium parameters, which is an effective means for the inversion of the seafloor sediments. However, the interface wave is difficult to use for ultrasonic nondestructive material characterization, especially for stiff and dense solid materials, owing to the mode shape or wave structure of the liquid-solid interface waves.The fraction of the total wave energy that travels in the fluid compared with the solid depends on the properties of the solid material. Usually, for a stiff and dense solid compared with the fluid, most of the energy travels in the fluid, while for a soft solid more energy travels in the solid. Therefore, it is difficult to use this kind interface wave for stiff solid material characterization. However, in the case of liquid-coated solid interface, the behaviors and properties of interface waves are quite different.In this paper, we use pulsed laser to generate the interface waves at the water-coated solid interfaces. The theoretical analysis of the laser-induced excitation of acoustic waves propagating along a plane interface between liquid and layered elastic solid is perforemd first. The general solution for the interface motion is derived. The analytic expression of the transient response is then obtained. Based on this expression, the dispersion characteristics of the interface waves, which propagate along the fluid-coated solid interface for the cases of slow coating on fast substrate and fast coating on slow substrate, are calculated and analyzed. The transient response signals are further calculated. In the case of slow coating on fast substrate, the interface wave shows an evident dispersion, in which its phase velocity is larger than its group velocity. In the case of fast coating on slow substrate, the interface wave also shows a remarkable dispersion within a smaller frequency-thickness product range, in which its phase velocity is less than its group velocity. The theoretical transient signals show the same properties.In order to verify the theoretical results, an experimental system is set up, and the interface waves are generated and measured. The experimental system mainly consists of pulsed laser, hydrophone, oscilloscope, and movable translation stage. The pulsed laser is used to excite the interface waves, and the hydrophone mounted on the movable translation stage is placed near the interface to receive the signals. Two kinds of samples of slow coating on fast substrate and fast coating on slow substrate are made and measured. The recorded testing signals are then processed and analyzed.The theoretical results and the experimental ones are in good agreement. The research results presented in this paper can provide theoretical basis for ultrasonic nondestructive characterization of coating and film material in immersion testing mode, and also for seafloor sediment parameter inversion.

Dual-comb spectroscopy for rapid characterization of complex optical properties of solids

We demonstrate rapid characterization of complex optical properties of solids via dual-comb spectroscopy (DCS) in the near-infrared region. The fine spectral structures in the complex refractive index of an Er:YAG are successfully deduced using the developed system and Fourier analysis. Moreover, simultaneous determination of the refractive index and the thickness is demonstrated for a silicon semiconductor wafer through the use of multireflected echo signals. The results indicate the potential of DCS as a powerful measurement tool for the rapid and full characterization of solid materials.

How to Process Zillions of Spectra from Spectral Imaging Datasets? From Phase-Mapping to Bulk-Chemistry on Micron- to Centimeter Scale Using PARC

Scanning Electron Microscopy (SEM) combined with microanalysis is widely used for characterization of solid materials. With the current generation of hardware, 1) the intense Field Emission Gun beams, 2) Energy Dispersive X-ray analysis system using Silicon Drift Detectors (SDD) and 3) the fast acquisition hardware technology, the chemical information from each pixel in the SEM field can be acquired within microseconds. In other words, for a typical field of 512x384 pixels a Spectral Image (SI) of sufficient quality for quantitative analysis can be obtained in five minutes. The greatest challenge now is how most efficiently to extract maximum information out of all these zillions of spectra. At CRC we have developed the post-processing software PARC for precisely this purpose.

Atom probe tomography of nanostructures

Atom probe tomography (APT) constitutes a rather unique analytical technique for the 3D elemental characterization of solid materials with potentially sub‐nm spatial resolution. APT is, therefore, very well suited for the analysis of a nanostructured specimen such as matrix‐embedded nanoparticles, ultra‐thin films and junctions, grain boundaries, and others. This presentation will emphasize these capabilities, describing three methods of data mining that can be used to fully exploit APT: (i) Visualization of atomic lattice planes in crystalline specimens, (ii) the determination of iso‐concentration surfaces and proximity histograms derived thereof, and (iii) a cluster identification algorithm based on maximum‐atom separations. These approaches will be illustrated by means of different types of samples: a crystalline tungsten specimen, a Fe/Cr/Fe multilayer system, Si nanocrystals embedded in a silicon oxide matrix, and Mg clustering in GaN. The results demonstrate clearly that sub‐nm‐sized structures can be characterized by APT. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Substance identification based on transmission THz spectra using library search

Over recent years terahertz spectroscopy has become a new tool for the characterization of solid materials, in particular for investigating polymorphism and crystallinity in pharmaceutics. Search strategies have been tested for THz spectra of various organic compounds with their spectra taken from the Riken database (http://www.riken.jp), using the GRAMS spectroscopy software. A subset of the entire database was used, which had been processed by removal of atmospheric water vapour lines and smoothing applied based on Savitzky-Golay convolution or time domain filtering. The spectral range available for all library substances was restricted to an interval from 0.9 to 4.5 THz (30–150cm−1). The number of vibrational bands within this spectral range is much reduced compared with mid-infrared or Raman spectra. The appropriateness of spectral pre-treatment is demonstrated with regard to reliability and robustness of the search methods. In particular, time-domain filters for smoothing and pre-treatment by the removal of water lines and etalon effects have been successfully tested in combination with least squares and correlation methods. With these insights, applications for substance identification, especially for the pharmaceutical industry, may be enlarged.

Requirements to consider when choosing a thermochemical material for solar energy storage

Solar thermochemical reactors offer good potential for production of heat for residential space heating and cooling and domestic hot water. The materials able to store solar energy are called thermochemical materials which are based on reversible chemical reactions, focusing here on solid–gas ones. These materials are capable to store solar thermal energy in one direction and to release it in the other, whenever is needed, with almost no heat losses. In the literature several materials have been successfully analyzed and tested at lab scale, but the expected heat storage capacity, or yield, of the reactor implementing these materials is not achieved. This paper shows that in order to reach the calculated operation conditions, a detailed and proper characterization of solid materials involved is needed (including solubility of the reactants and products, and evaluation of the crystallographic structure changes). Furthermore, a reliable kinetic model should be obtained to predict further behavior and to design the suitable reactor. The main goal of this paper is to provide a correct pathway to obtain the reliable kinetic model regarding important solid features that should be considered when working on thermochemical energy storage.