Extraction Of Material Properties Research Articles

Perovskite solar cells: a deep analysis using current\u2013voltage and capacitance\u2013voltage techniques

Perovskite solar cells exhibiting ~ 14–15% efficiency were experimentally measured using current–voltage (I–V) and capacitance–voltage (C–V) techniques in order to extract material and device properties, and understand the action of photovoltaic (PV) operation. Deep analyses were carried out on dark- and illuminated I–V curves, and dark C–V curves. Results were compared with those of graded bandgap solar cells fabricated on inorganic n-type window layers. These analyses according to a physicist’s point of view lead to understand the perovskite solar cell as a graded bandgap solar cell built on a p-type window layer. I–V and C–V results show very similar behaviour and the principle of PV action is identical. Once the stability issues with perovskites are solved, these devices have very high potential of producing next generation solar cells reaching at least mid-20% efficiency values.

Effects of Sample and Indenter Configurations of Nanoindentation Experiment on the Mechanical Behavior and Properties of Ductile Materials

The nanoindentation test is frequently used as an alternate method to obtain the mechanical properties of ductile materials. However, due to the lack of information about the effects of the sample and indenter physical configurations, the accuracy of the extracted material properties in nanoindentation tests requires further evaluation that has been considered in this study. In this respect, a demonstrator ductile material, aluminum 1100, was tested using the Triboscope nanoindenter system with the Berkovich indenter. A 3D finite element simulation of the nanoindentation test was developed and validated through exact prediction of the structural response with measured data. The validated model was then employed to examine the effects of various test configurations on the load–displacement response of the sample material. These parameters were the different indenter edge-tip radii, different indentation depths, different sample tilts, and different friction conditions between the indenter and the material surface. Within the range of the indenter edge-tip radii examined, the average elastic modulus and hardness were 78.34 ± 14.58 and 1.6 ± 0.24 GPa, respectively. The different indentation depths resulted in average values for the elastic modulus and hardness of 77.03 ± 6.54 and 1.58 ± 0.17 GPa, respectively. The uneven surface morphology, as described by the inclination of the local indentation plane, indicated an exponential increase in the extracted values of elastic modulus and hardness, ranging from 71.83 and 1.47 GPa (for the reference case, θ = 0°) to 243.39 and 5.05 GPa at θ = 12°. The mechanical properties that were obtained through nanoindentation on the surface with 6° tilt or higher were outside the range for aluminum properties. The effect of friction on the resulting mechanical response and the properties of the material was negligible.

Method of printed circuits and semiconductor substrates material parameters extraction using wideband reflection measurements

This paper is dedicated to a new method of high frequency circuits material properties extraction based on the reflection measurements of a line shorted two or more times along its length. The line should be fabricated on the material under test. To achieve more precise calculation results, the proposed method uses processing in the time domain. The experimental results section shows obtained assessments for relative permittivity and dielectric loss tangent of the RO4350B hydrocarbon ceramic laminate. Measurements have been conducted over the frequency range up to 20 GHz.

Ptychographic imaging with partially coherent plasma EUV sources

Abstract We report on high-resolution lens-less imaging experiments based on ptychographic scanning coherent diffractive imaging (CDI) method employing compact plasma sources developed for extreme ultraviolet (EUV) lithography applications. Two kinds of discharge sources were used in our experiments: a hollow-cathode-triggered pinch plasma source operated with oxygen and for the first time a laser-assisted discharge EUV source with a liquid tin target. Ptychographic reconstructions of different samples were achieved by applying constraint relaxation to the algorithm. Our ptychography algorithms can handle low spatial coherence and broadband illumination as well as compensate for the residual background due to plasma radiation in the visible spectral range. Image resolution down to 100 nm is demonstrated even for sparse objects, and it is limited presently by the sample structure contrast and the available coherent photon flux. We could extract material properties by the reconstruction of the complex exit-wave field, gaining additional information compared to electron microscopy or CDI with longer-wavelength high harmonic laser sources. Our results show that compact plasma-based EUV light sources of only partial spatial and temporal coherence can be effectively used for lens-less imaging applications. The reported methods may be applied in combination with reflectometry and scatterometry for high-resolution EUV metrology.

Uncertainty analysis in composite material properties characterization using digital image correlation and finite element model updating

This work presents an uncertainty analysis on composite material constitutive parameters, which are extracted using digital image correlation (DIC) and finite-element-model-updating (FEMU). The uncertainty is induced by the measurement system noise in the DIC technique and the approximation error in the displacements and strains smoothing algorithm. The covariance matrix of the extracted material constitutive parameters has been given explicitly. Six material constitutive parameters were identified from a customized short-shear experiment simultaneously using an estimated optimal reconstruction mesh size as an illustration. Sensitivity of measurement noise and reconstruction parameter on extracted material properties has been investigated. The effects of region of interest (ROI) and DIC image number on uncertainties of extracted material properties have been addressed. It is suggested that there exist an appropriate ROI and the number of images, from which reliable material parameters can be identified, but much more data used in identification process always lead to smaller standard deviation and COV. It is observed that the material constants used to characterize the in-plane shear stress-strain behavior show strong robustness to the measurement noise. However, the identified longitudinal Young’s modulus is more sensitive to the measurement noise. Another key finding is that the reconstruction parameter in the global finite-element based approximation approach is critical for reliable material properties identification. Its value has to stay close to optimum for guaranteeing reliable identification of material properties.

Improved “Root-Omega” Method for Transmission-Line-Based Material Property Extraction for Multilayer PCBs

Electrical properties of dielectric substrate are critical in designing high-speed products in terms of signal and power integrity. It is important to accurately characterize the dielectric properties to avoid overestimating or underestimating in the design. This paper proposes the improved “Root-Omega” method for extracting dielectric properties from fabricated multilayer printed circuit boards. Based on the electrical properties of fabricated transmission lines, the improved “Root-Omega” method applied to cases with smooth and rough conductors is validated using simulations. Error sensitivity analysis is performed to demonstrate the potential errors in the original “Root-Omega” procedure and the error sensitivity is significantly reduced by the proposed improvements.

A dynamic model for series and parallel resistance of photovoltaic cell using material properties extraction and energy tunnel

This article presents a novel model for the equivalent circuit of a photovoltaic module. This circuit consists of the following important parameters: a single diode, series resistance (Rs) and parallel resistance (Rp) that can be directly adjusted according to ambient temperature and the irradiance. The single diode in the circuit is directly related to the ideality factor (m), which represents the relationship between the materials and significant structures of PV module such as mono crystalline, multi crystalline and thin film technology.
 Especially, the proposed model in this article is to present the simplified model that can calculate the results of I-V curves faster and more accurate than other methods of the previous models. This can show that the proposed models are more suitable for the practical application.
 In addition, the results of the proposed model are validated by the datasheet, the practical data in the laboratory (indoor test) and the onsite data (outdoor test). This ensures that the less than 0.1% absolute errors of the model can be accepted.

Experimental and computational analysis of micromotions of an uncemented femoral knee implant using elastic and plastic bone material models

It is essential to calculate micromotions at the bone-implant interface of an uncemented femoral total knee replacement (TKR) using a reliable computational model. In the current study, experimental measurements of micromotions were compared with predicted micromotions by Finite Element Analysis (FEA) using two bone material models: linear elastic and post-yield material behavior, while an actual range of interference fit was simulated. The primary aim was to investigate whether a plasticity model is essential in order to calculate realistic micromotions. Additionally, experimental bone damage at the interface was compared with the FEA simulated range.TKR surgical cuts were applied to five cadaveric femora and micro- and clinical CT- scans of these un-implanted specimens were made to extract geometrical and material properties, respectively. Micromotions at the interface were measured using digital image correlation. Cadaver-specific FEA models were created based on the experimental set-up. The average experimental micromotion of all specimens was 53.1±42.3µm (mean±standard deviation (SD)), which was significantly higher than the micromotions predicted by both models, using either the plastic or elastic material model (26.5±23.9µm and 10.1±10.1µm, respectively; p-value<0.001 for both material models). The difference between the two material models was also significant (p-value<0.001). The predicted damage had a magnitude and distribution which was comparable to the experimental bone damage. We conclude that, although the plastic model could not fully predict the micro motions, it is more suitable for pre-clinical assessment of a press-fit TKR implant than using an elastic bone model.

Finite amplitude effects on drop levitation for material properties measurement

The method of exciting shape oscillation of drops to extract material properties has a long history, which is most often coupled with the technique of acoustic levitation to achieve non-contact manipulation of the drop sample. We revisit this method with application to the inference of bulk shear viscosity and surface tension. The literature is replete with references to a “10% oscillation amplitude” as a sufficient condition for the application of Lamb's analytical expressions for the shape oscillations of viscous liquids. Our results show that even a 10% oscillation amplitude leads to dynamic effects which render Lamb's results inapplicable. By comparison with samples of known viscosity and surface tension, we illustrate the complicating finite-amplitude effects (mode-splitting and excess dissipation associated with vorticity) that can occur and then show that sufficiently small oscillations allow us to recover the correct material properties using Lamb's formula.

Extracting Material Properties from Relaxation Experiments

Redox active oxides, with mixed ionic and electronic conductivity (MIEC), are critical components in a wide range of energy technologies, serving as electrodes in fuel cells and batteries, and as reactive substrates in solar-driven thermochemical reactors. Accurate knowledge of the surface reaction rate constant, k S, is essential for both optimal design of components using existing materials and rational discovery of new materials with enhanced catalytic activity. A variety of relaxation methods have been used extensively to determine k S. Such approaches rely on the change in some measurable property, most commonly conductivity, upon application of a step change in gas-phase oxygen partial pressure. Under the appropriate experimental conditions, the rate at which the property changes in response to the change in gas-phase oxygen chemical potential provides a direct measure of the material kinetic parameters. Here, we present several considerations relevant to accurate extraction of these parameters, with particular focus on identifying relaxation occurring due to thermodynamic rather than material kinetic reasons. Furthermore, while the electrical conductivity relaxation (ECR) method is one of the most widely employed relaxation techniques because of the ease with which high precision conductivity measurements can be made using samples of almost arbitrary dimensions, ECR is impractical for the evaluation of a material in which the change in conductivity in response to change in oxygen partial pressure is extremely small. For such materials mass relaxation emerges as a viable alternative measurement approach. To this end, we describe a high temperature mass relaxation apparatus based on a gallium phosphate piezocrystal microbalance that enables measurements at temperatures as high 700 °C.

Material and Morphological Heat Transfer Properties of Fuel Cell Porous Transport Layers

The complex structure of the porous transport layer (PTLs), commonly referred to as gas diffusion layers (GDL), makes direct measurement of thermal transport properties difficult. Typically, effective thermal conductivity values are obtained experimentally and computational models are developed to replicate the measurements. This approach is sufficient for generalized one-dimensional models of fuel cell performance, but is not sufficient to predict reactant maldistribution due to the presence of liquid water in the PTL. Further, the anisotropy in the PTL structure results in dissimilar properties for through-plane and in-plane transport. In this work an analytical model is developed to extract material properties from effective thermal conductivity measurements. The model accounts for the change in the effective thermal conductivity as a function of compression. Geometric changes due to compression are separated from morphological changes using a compression modulation function; the shape of which is indicative of how fiber-to-fiber contact morphology changes with respect to strain. Material and morphological properties are determined using effective thermal conductivity data for three commercial PTLs. The properties also enable prediction of in-plane heat transfer using through-plane empirical data and also provide insight into morphological changes due to compression.

Analyzing spinodal decomposition of an anisotropic fluid mixture

Spinodal decomposition leads to spontaneous fluctuations of the local concentration. In the early stage, the resulting pattern provides explicit information about the material properties of the mixture. In the case of two isotropic fluids, the static structure factor shows the characteristic ring shape. If one component is a liquid crystal, the pattern is typically anisotropic and the structure factor is more complex. Using numerical methods, we investigate how structure factors can be used to extract information about material properties like the diffusion constant or the isotropic and the anisotropic contributions to the interfacial tension. The method is based on momenta taken from structure factors in the early stage of the spinodal demixing. We perform phase field calculations for an isotropic and an anisotropic spinodal decomposition. A comparison of the extracted results with analytic values is made. The calculations show that linear modes dominate in the beginning of the growth process, while non-linear modes grow monotonously in the region of the k-space for which damping is predicted by the linearized theory. As long as non-linear modes are small enough, linearized theory can be applied to extract material properties from the structure factor.

A novel piezoresistive polymer nanocomposite MEMS accelerometer

A novel polymer MEMS (micro electro mechanical systems) accelerometer with photo-patternable polymer nanocomposite as a piezoresistor is presented in this work. Polymer MEMS Accelerometer with beam thicknesses of 3.3 µm and embedded nanocomposite piezoresistive layer having a gauge factor of 90 were fabricated. The photosensitive nanocomposite samples were prepared and characterized for analyzing the mechanical and electrical properties and thereby ensuring proper process parameters for incorporating the piezoresistive layer into the polymer MEMS accelerometer. The microfabrication process flow and unit processes followed are extremely low cost with process temperatures below 100 °C. This also opens up a new possibility for easy integration of such polymer MEMS with CMOS (complementary metal oxide semiconductor) devices and circuits. The fabricated devices were characterized using laser Doppler vibrometer (LDV) and the devices exhibited a resonant frequency of 10.8 kHz and a response sensitivity of 280 nm g−1 at resonance. The main focus of this paper is on the SU-8/CB nanocomposite piezoresistive MEMS accelerometer technology development which covers the material and the fabrication aspects of these devices. CoventorWare FEA analysis performed using the extracted material properties from the experimental characterization which are in close agreement to performance parameters of the fabricated devices is also discussed. The simulated piezoresistive polymer MEMS devices showed an acceleration sensitivity of 126 nm g−1 and 82 ppm of ΔR/R per 1 g of acceleration.

Electrochemical-Thermal Characterization and Modeling of Large Format Prismatic Lithium Ion Batteries

Large-format prismatic lithium-ion cells can generate substantial heat during operation, making thermal management significant. Some cells have high surface-to-volume ratios, and the positioning of tabs can make surface temperature highly non-uniform [1], posing further thermal management challenges. Non-uniformity of temperature is a major problem because a battery operated at a safe average temperature can still have ‘hot spots’ that are prone to thermal runaway [2]. Depending on the battery’s ability to dissipate heat to its surroundings, thermal runaway may nucleate in very small volumes. The thermal responses of prismatic lithium-ion batteries arise from a number of distinct phenomena that occur as the cell is subjected to an electrical load. Current flow generates joule heat, which is always dissipated, regardless of the sign of the current; this may arise either from ohmic resistance or from the resistances associated with charge-transfer reactions. There is also reversible heat, which may be dissipated or consumed according to the current’s sign; such heat owes to the entropy associated with the electrochemical reaction that occurs as the state of charge (SOC) is changed [3]. We have developed a 3D finite-element model that accounts for these various modes of heating within the battery cell, which runs with sufficient computational efficiency to allow parameterization by fitting model output to dynamic experimental voltage and temperature-distribution data. Our approach provides an ‘outside-in’ method that allows external measurements to be correlated with internal material properties. A simple physics-based model based on the Newman-Tobias porous-electrode theory [4] is augmented with energy equations to predict electrical and thermal behavior. The model can then also be used to extract material properties. We aim to characterize the macroscopic effects of charge/discharge induced thermal response across a cell’s available charge states to provide insight into battery state of health (SOH). Square wave signals with amplitudes of C-rates ranging from 1C to 4C and periods ranging from 20s to 100s were applied to A123 20Ah LiFePO4 prismatic cells beginning at fixed SOC. This input signal was chosen so that the average SOC remains constant, eliminating concerns regarding how material properties change depending on charge state. Temperature distributions were measured using infrared thermography; this data was gathered dynamically and synchronized with the cell-voltage data gathered during the square-wave excitation tests. Figure 1 shows typical temperature distributions across three C-rates (1C, 2C, 4C) at a fixed period of 100s at an average SOC of 50%. As C-rate increases, not only does the overall temperature of the cell increase, but the difference in temperature across its surface also varies. Material properties of batteries – including the propensity for thermal runaway – depend strongly on SOC [5]. By fitting the thermographic data gathered around different mean SOCs, it is possible to extract these SOC-dependent parameter values. Some discussion will also touch on how the model can be used to track material properties as they vary with respect to cycling history, providing possible insight into SOH estimation. 1. Robinson, J.B., et al., Detection of Internal Defects in Lithium-Ion Batteries Using Lock-in Thermography. ECS Electrochemistry Letters, 2015. 4(9): p. A106-A109. 2. Bandhauer, T.M., S. Garimella, and T.F. Fuller, A Critical Review of Thermal Issues in Lithium-Ion Batteries. Journal of The Electrochemical Society, 2011. 158(3): p. R1-R25. 3. Thomas, K.E. and J. Newman, Heats of mixing and of entropy in porous insertion electrodes. Journal of Power Sources, 2003. 119–121: p. 844-849. 4. Newman, J.S. and C.W. Tobias, Theoretical Analysis of Current Distribution in Porous Electrodes. Journal of The Electrochemical Society, 1962. 109(12): p. 1183-1191. 5. Maleki, H., et al., Thermal Stability Studies of Li‐Ion Cells and Components. Journal of The Electrochemical Society, 1999. 146(9): p. 3224-3229. Figure 1

An X-band waveguide measurement technique for the accurate characterization of materials with low dielectric loss permittivity.

In this work, we present a new X-band waveguide (WR90) measurement method that permits the broadband characterization of the complex permittivity for low dielectric loss tangent material specimens with improved accuracy. An electrically long polypropylene specimen that partially fills the cross-section is inserted into the waveguide and the transmitted scattering parameter (S21) is measured. The extraction method relies on computational electromagnetic simulations, coupled with a genetic algorithm, to match the experimental S21 measurement. The sensitivity of the technique to sample length was explored by simulating specimen lengths from 2.54 to 15.24 cm, in 2.54 cm increments. Analysis of our simulated data predicts the technique will have the sensitivity to measure loss tangent values on the order of 10(-3) for materials such as polymers with relatively low real permittivity values. The ability to accurately characterize low-loss dielectric material specimens of polypropylene is demonstrated experimentally. The method was validated by excellent agreement with a free-space focused-beam system measurement of a polypropylene sheet. This technique provides the material measurement community with the ability to accurately extract material properties of low-loss material specimen over the entire X-band range. This technique could easily be extended to other frequency bands.

Biodegradable Polymeric Films Incorporated with Nisin: Characterization and Efficiency against Listeria monocytogenes

Nisin (0.2 IU per cm2 films) containing biodegradable films were produced from pea protein isolate (PPI), whey protein isolate (WPI), and polylactic acid (PLA). Nisin was released over 4 h at 22 °C and 8 h at 4 °C. PPI released more nisin compared to other films suppressing the growth of Listeria monocytogenes (P < 0.05) based upon diffusion into agar and liquid culture media. The population of bacteria after 48 h in liquid media was 6 CFU/mL (1 log10 increase) in PPI, 8.47 CFU/mL (3.47 log10 increase) in WPI and 9 CFU/mL (4 log10 increase) in PLA, which was significantly lower in protein based films compared to PLA (P < 0.05). The inhibition zone in agar test was significantly higher (P < 0.05) in PPI and WPI, compared to PLA film, which might be due to the higher hydration in protein based films. Fourier transform infrared spectroscopy (FTIR) showed that nisin altered the intensity of amide I peaks in protein based films suggesting that nisin can bind to the protein functional groups in PPI and WPI. Thermogram showed that nisin did not influence the glass transition and melting temperatures of the films. Nisin containing films exhibited significantly lower enthalpy compared to control films (P < 0.05). PeakForce Quantitative Nano Mechanical Property Mapping (PeakForce QNM) was applied to extract material and mechanical properties in PPI, WPI and PLA films with and without nisin. Results showed significant reductions in material and mechanical properties of protein based films containing nisin compared to PLA films.

Compressional rheology: A tool for understanding compressibility effects in sludge dewatering

Water and wastewater treatment sludges exhibit compressible behaviour due to flocculation and aggregation. At a critical solids concentration called the gel point, which is as low as 1–2 v/v%, a continuous interconnected network of particles is formed that can resist an applied load. The applied load (mechanical filtration pressure or buoyancy in settling for example) must exceed the network strength in order to consolidate the network. The network strength increases with solids concentration such that the equilibrium extent of consolidation is a function of the applied load. Improved understanding of the nature of compressible suspensions can have a significant impact through optimising design and operation of sludge handling and dewatering processes. This work gives an overview of compressional rheology, which has proven to be a useful tool for describing the solid–liquid separation of compressible systems. This is followed by three examples where compressibility effects must be taken into account, namely the extraction of material properties for extremely compressible materials, consolidation and crust formation during constant rate evaporation, and the effect of bed height in thickening.

Transient modeling of ultrasonic guided waves in circular viscoelastic waveguides for inverse material characterization

In this contribution, we present an efficient approach for the transient and time-causal modeling of guided waves in viscoelastic cylindrical waveguides in the context of ultrasonic material characterization. We use the scaled boundary finite element method (SBFEM) for efficient computation of the phase velocity dispersion. Regarding the viscoelastic behavior of the materials under consideration, we propose a decomposition approach that considers the real-valued frequency dependence of the (visco-)elastic moduli and, separately, of their attenuation. The modal expansion approach is utilized to take the transmitting and receiving transducers into account and to propagate the excited waveguide modes through a waveguide of finite length. The effectiveness of the proposed simulation model is shown by comparison with a standard transient FEM simulation as well as simulation results based on the exact solution of the complex-valued viscoelastic guided wave problem. Two material models are discussed, namely the fractional Zener model and the anti-Zener model; we re-interpret the latter in terms of the Rayleigh damping model. Measurements are taken on a polypropylene sample and the proposed transient simulation model is used for inverse material characterization. The extracted material properties may then be used in computer-aided design of ultrasonic systems.

Evaluating indent pile-up with metallic films on ceramic-like substrates

Abstract

The robustness of an algorithm applied in wafer-level material property extraction

In this paper, the robustness of a wafer-level testing algorithm was analyzed and the Taguchi methods were used to perform variability analysis on the effects of differences in test key structural length (?L), material crystal direction, and structural length on the Young's modulus (E) and mean stress (?0) of thin films. TSMC 0.18 μm process metal 2 was used as the test structure material for performing material parameter extraction. The results of this study indicate that structural length difference is the most crucial prominent factor and substantially affects the robustness of this algorithm. Besides, the Taguchi method analysis was then used to determine the suitable scope of application for this algorithm, and determine the optimal test key geometric parameter design that can be used for designing test keys.