Diffusion Resistance Research Articles

Synergistic analysis of oxygen transport resistance in polymer electrolyte membrane fuel cells

The oxygen transport resistance of polymer electrolyte membrane fuel cells operated under various conditions (e.g., temperature and relative humidity) was separated into molecular diffusion, Knudsen diffusion, and ionomer film (IF) resistances using the catalyst agglomerate model, dissection of oxygen transport resistance, and distribution of relaxation time analysis. Simultaneously, an analysis of resistance, including charge transfer, proton transfer, and high-frequency resistances, was performed. The Knudsen diffusion resistance of the catalyst layer was calculated by assessing the effects of relative humidity on porosity and pore size. Oxygen transport resistance was analyzed to establish a correlation between temperature, relative humidity, and IF resistance. Water negligibly impacted performance at low oxygen levels at all examined current densities. The fractional contributions of molecular diffusion, Knudsen diffusion, and IF resistances obtained using oxygen transport analysis could be effectively applied to mass transport resistance in the distribution of relaxation time analysis. The IF resistance in the catalyst layer was up to eight times higher than the Knudsen diffusion resistance and 150 times higher than the proton transfer resistance across all current densities, thus most strongly contributing to the catalyst layer resistance. In the gas diffusion layer, the molecular diffusion resistance was up to four times higher than the Knudsen diffusion resistance. Thus, we examined the relationship between the mass transport resistances of individual elements and IF behavior under different operating conditions, revealing that the design of the IF in the catalyst should be considered alongside the relationship between the gas diffusion layer and membrane for optimal performance.

An approach to select between the plausible kinetic models of a heterogeneous catalytic process using intraparticle diffusion with external mass transfer resistance

The reaction rate is sometimes thoroughly described by several kinetic models simultaneously. In this case, the discrimination of the particular model may be challenging. Herein, we demonstrate that a change in the rate-limiting step of a reaction mechanism may result in a significant deviation of the effectiveness factor even if the kinetic rate equations provide nearly identical reaction rates. On this basis, the comparison of the experimental effectiveness factor and the effectiveness factor calculated theoretically using the corresponding rate equations may shed light on the true reaction mechanism. Since many industrial processes operate under internal and external mass transfer limitations, the effectiveness factor is obtained by accounting for pore diffusion resistance and diffusion resistance at the outer surface of a catalyst particle. Verification of the obtained formalism is performed using the kinetic constants for the commercially available process of the methanol dehydration to dimethyl ether over γ-alumina catalyst.

Water droplet evaporation in air: Effects of interfacial thermal and mass diffusion resistance

Evaporation of water droplets in air is a process highly relevant to a variety of environmental, industrial, and biomedical applications. In conventional hydrodynamic modeling of droplet evaporation, it is usually assumed that thermodynamic equilibrium exists at the water-air interface. However, such an assumption could result in considerable errors in predicting the evaporation rate of micro/nanoscale water droplets in air. In this work, we use the combination of kinetic theory-based model and hydrodynamic model to study the effects of interfacial resistance on the evaporation behavior of water droplets in air. The interfacial thermal resistance and interfacial mass diffusion resistance predicted by the kinetic theory-based model are first validated by MD simulation results, and then incorporated into the hydrodynamic model to predict the influence of the water droplet size, air temperature, pressure and humidity on the water droplet evaporation rate and droplet temperature. The evaporation behavior of water droplets in air predicted by our kinetic-hydrodynamic model are corroborated by MD simulation results and the recent experimental data. Our modeling results show that, at normal temperature and pressure (i.e., 25 °C and 1 atm by NIST), the equivalent length of thermal resistance and mass diffusion resistance at water-air interface are both ∼200 nm. This indicates that, at normal temperature and pressure, the effects of interfacial thermal and mass diffusion resistance on evaporation of water droplets in air cannot be ignored if the droplet diameter is less than 20 μm. The thermodynamic equilibrium assumption is only valid if the droplet diameter is greater than 20 μm. Once the droplet size is greater than 100 μm, the radiation heat transfer and convection effects must also be taken into account to give a more accurate prediction of droplet evaporation rate.

Enzyme-particle Complexes Facilitate Pickering Interfacial Biocatalysis.

Pickering interfacial biocatalysis (PIB), where biocatalysts stabilize emulsions through carrier coupling or polymer grafting, has emerged as a powerful platform for organic synthesis due to its ability to accommodate water-insoluble substrates within enzymatic cascade reactions. PIB provides a large interfacial area for two-phase reactions, reducing diffusional resistance and enhancing transformation efficiency. The performance of PIB relies heavily on enzyme-particle conjugates, which serve a dual function: stabilizing the emulsion and acting as the active biocatalysts in the system. In this Concept, we discuss the latest advancements, current challenges, and future directions in the development of protein-particle conjugates for PIB.

Comportamento higrotérmico de tijolo cerâmico de olaria do sul do Brasil

Abstract The presence of moisture in buildings can lead to pathological manifestations, and the behavior of materials when exposed to various conditions can be predicted through computational simulations. For this purpose, the hygrothermal characteristics of building elements are paramount. In Brazil, there is a gap in studies on the hygrothermal properties of materials, compromising simulations. This article discusses the possibilities of using European data in simulating moisture transport in ceramic brick walls in the southern region of Rio Grande do Sul, Brazil. The results were generated by comparing hygrothermal simulations with WUFI Pro 6.5 using the simulation program database with data collected from laboratory tests on ceramic bricks from a southern Brazilian brickyard. Tests for water vapor diffusion resistance, water absorption, and hygroscopic curves were conducted. Although both situations led to the growth of filamentous fungi, experimental data led to3% lower values compared to database results. Regarding surface condensation, a likely higher occurrence was observed when using laboratory test data.

Catalytic gasification of a single coal char particle: An experimental and simulation study

The catalytic coal gasification technology has been widely researched and developed under the background of “Carbon peaking and carbon neutrality goals”. Currently, most of catalytic gasification experiments on coal char particles are analyzed by thermogravimetric analyzer (TGA). However, the gasification agent will be subject to diffusion resistance during the reaction because of the sample stacking, making the inherent reaction kinetics unclear. In this study, we investigated the catalytic gasification behavior of single-particle coal char using high temperature stage microscope (HTSM). With the diffusion resistance ruled out, the reaction conditions when using a HTSM are more similar to those inside a real industrial gasifier. Numerical models of the gasification reaction of single-particle coal char were further developed using the kinetic parameters obtained under HTSM. Three models were investigated, including regular spherical structured, irregular spherical structured and porous spherical structured models, representing different morphologies of coal char particles in the gasifier. The gasification characteristics of coal char particles under different K2CO3 catalyst loadings and gasification temperatures were also studied. Compared with the activation energies data of coal char particles without catalyst, the activation energies of coal char particles loaded with 2.2 %, 4.4 %, 6.6 %, and 10.0 % catalysts were reduced by 110 kJ/mol, 116 kJ/mol, 121 kJ/mol, and 126 kJ/mol, respectively. The reaction surface area affects the temperature distribution. The temperature near the irregular spherical particle is about 20 K higher than the temperature near the regular spherical particle.

Potassium-Based Solid Sorbents for CO2 Adsorption: Key Role of Interconnected Pores.

Industrial CO2 emissions contribute to pollution and greenhouse effects, highlighting the importance of carbon capture. Potassium carbonate (K2CO3) is an effective CO2 absorbent, yet its liquid-phase absorption faces issues like diffusion resistance and corrosion risks. In this work, the solid adsorbents were developed with K2CO3 immobilized on the selected porous supports. Al2O3 had an optimum CO2 adsorption capacity of 0.82 mmol g-1. After further optimization of its pore structure, the self-prepared support Al2O3-2, which has an average pore diameter of 11.89 nm and a pore volume of 0.59 cm3 g-1, achieved a maximum CO2 adsorption capacity of 1.12 mmol g-1 following K2CO3 impregnation. Additionally, the relationship between support structure and CO2 adsorption efficiency was also analyzed. The connectivity of the pores and the large pore diameter of the support may play a key role in enhancing CO2 adsorption performance. During 10 cycles of testing, the K2CO3-based adsorbents demonstrated consistent high CO2 adsorption capacity with negligible degradation.

Enhanced VOCs adsorption over ZSM-5 nanosheets with different thicknesses along the b-axis

A systematic study was conducted on the effect of the b-axis thickness on the adsorption/desorption properties of representative VOCs (toluene and dichloromethane) by varying the diffusion resistance over ZSM-5 nanosheets. ZSM-5 nanosheets with about 30 nm thickness along the b-axis (Z5-3) presented a 1.3-fold higher adsorption capacity (83.9 mg/g) and 27 % enhancement in breakthrough times for toluene (38 min) compared with conventional ZSM-5 (Z5-4). Dichloromethane adsorption capacity on Z5-3 (micropore volume of 0.12 cm3/g) was approximately 53 % higher than that on Z5-4 (micropore volume of 0.08 cm3/g) and only weekly correlated to the b-axis thickness due to its small molecular size. The adsorption isotherms and molecular dynamic simulations indicated that a shorter b-axis thickness enhanced the diffusion of toluene (3.9 × 10-5 cm2/s) and dichloromethane (7.2 × 10-5 cm2/s), as well as the toluene adsorption capacities over ZSM-5 samples. The toluene and dichloromethane physisorption mechanism was verified by adsorption kinetics. Additionally, the toluene and dichloromethane adsorption capacities of all samples decreased by about 33 % and 21 % at a relative humidity (RH) of 50 % at 298 K, respectively. This indicated that the structure of ZSM-5 samples did not significantly affect their hydrophobicity. Moreover, according to the competitive adsorption test results, toluene and dichloromethane underwent successive co-adsorption, competitive adsorption, and equilibrium adsorption. These findings are useful for designing high-performance and cost-effective zeolite adsorbents to efficiently remove volatile organic compounds from industrial sources.

Various Cultivars of Citrus Fruits: Effects of Construction on Gas Diffusion Resistance and Internal Gas Concentration of Oxygen and Carbon Dioxide

Various cultivars of citrus fruits have unique constructions, such as thick outer skin. These constructions generate gas diffusion resistance between the atmosphere and the fruit, which can limit the gas exchange of O2 and CO2.This has not been sufficiently investigated. This study on seven cultivars of citrus fruit firstly aimed to investigate gas diffusion resistance utilizing the ethane efflux method; secondly, this study aimed to investigate the internal gas concentration of O2 and CO2. As a result, a cultivar of citrus fruit with slimmer outer skin thickness had lower resistance. For the internal gas, a high CO2 concentration in comparison with the atmosphere was observed even in the fruits with the minimum resistance, and no considerable difference was observed among all cultivars, regardless of the gas diffusion resistance value. However, when the fruits were stored at 25 °C for 2 weeks, CO2 gas concentration tended to increase and O2 gas concentration tended to decrease, with an increase in the resistance value. Therefore, when the respiration of citrus fruits is activated at ambient temperature, the self-control system of internal gas concentration can be driven to suppress the respiration which was induced by gas diffusion resistance generated from their construction.

Ingrown Leading to Hierarchical SAPO‐34 with High Catalytic Activity

AbstractIntroduce meso/macro‐pore to the crystal of SAPO‐34 is an efficient way to overcome its inherent diffusion resistance. Porogen, formation hierarchical structure by inhibiting the growth of the crystals, would increase the costs of SAPO‐34 and is usually not friendly to environment. In this work, an ingrowth route to synthesize hierarchical SAPO‐34 is developed by secondary silica addition via hydrothermal method. Hierarchical porous SAPO‐34 was synthesized without adding any pore‐generating agent. Secondary silica addition put off the Si and P transferring from the mother liquid to gel phase, leading to the chemical composition of surface first meeting to the crystallization conditions. Then the crystallization started from the surface to the inside of the amorphous particles. The hierarchical SAPO‐34 showed numerous meso/macro pore structure and weaker acid strength. So the hierarchical SAPO‐34 showed better catalytic activity than the conventional SAPO‐34 in MTO reaction.

Copper diffusion hindrance in Ti-TM (TM = W, Ru) alloys: A first-principles insight

This study utilizes DFT calculations to assess the effectiveness of Ti-TM (TM = W, Ru) alloys in obstructing copper diffusion, a pivotal factor for semiconductor device reliability. The calculated diffusion barriers for Cu in TiRu and Ti4W12 alloys are found to be 0.48 eV and 0.34 eV, respectively, significantly surpassing the 0.25 eV barrier for Cu diffusion in Si. This comparative analysis highlights the enhanced diffusion resistance of these alloys, with TiRu displaying a barrier nearly twice that of Si. An in-depth examination of the electronic structure and microstructural attributes of the alloys indicates that atomic interactions at the Cu/Ti-TM interface play a crucial role in hindering Cu diffusion. The local density of states, charge density differences, and electron localization functions were scrutinized to clarify the nature of these interactions. The research uncovers that the combined action of Ru, W, Cu, and Ti atoms leads to a synergistic strengthening of the diffusion barrier, implying a robust interatomic repulsion that restricts Cu migration. The findings contribute to a deeper fundamental understanding of Cu diffusion mechanisms in Ti-TM alloys and offer a scientific basis for the judicious selection of materials for diffusion barrier layers. The study supports the further exploration and potential application of TiRu and Ti4W12 alloys in the semiconductor industry.

MgAl-Layered Double Hydroxide-Coated Bio-Silica as an Adsorbent for Anionic Pollutants Removal: A Case Study of the Implementation of Sustainable Technologies.

The adsorption efficiency of Cr(VI) and anionic textile dyes onto MgAl-layered double hydroxides (LDHs) and MgAl-LDH coated on bio-silica (b-SiO2) nanoparticles (MgAl-LDH@SiO2) derived from waste rice husks was studied in this work. The material was characterized using field-emission scanning electron microscopy (FE-SEM/EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopic (XPS) techniques. The adsorption capacities of MgAl-LDH@SiO2 were increased by 12.2%, 11.7%, 10.6%, and 10.0% in the processes of Cr(VI), Acid Blue 225 (AB-225), Acid Violet 109 (AV-109), and Acid Green 40 (AG-40) dye removal versus MgAl-LDH. The obtained results indicated the contribution of b-SiO2 to the development of active surface functionalities of MgAl-LDH. A kinetic study indicated lower intraparticle diffusional transport resistance. Physisorption is the dominant mechanism for dye removal, while surface complexation dominates in the processes of Cr(VI) removal. The disposal of effluent water after five adsorption/desorption cycles was attained using enzymatic decolorization, photocatalytic degradation of the dyes, and chromate reduction, satisfying the prescribed national legislation. Under optimal conditions and using immobilized horseradish peroxidase (HRP), efficient decolorization of effluent solutions containing AB-225 and AV-109 dyes was achieved. Exhausted MgAl-LDH@SiO2 was processed by dissolution/precipitation of Mg and Al hydroxides, while residual silica was used as a reinforcing filler in polyester composites. The fire-proofing properties of composites with Mg and Al hydroxides were also improved, which provides a closed loop with zero waste generation. The development of wastewater treatment technologies and the production of potentially marketable composites led to the successful achievement of both low environmental impacts and circular economy implementation.

Assessment of interfering/synergistic effects in the adsorption between polar and non-polar VOCs on a commercial biomass-based microporous carbon

This research has been carried out to investigate unique relationships in adsorption behavior between polar and non-polar volatile organic compounds (VOCs: formaldehyde (FA) versus toluene) using commercial macadamia nutshell (MNS)-based microporous activated carbon (i.e., Procarb-900: namely, P900). The breakthrough (BT) volume, adsorption capacity, and partition coefficient of P900 are estimated for 100 ppm FA as a single component and as a binary phase with 100 ppm toluene. The contrasting features of adsorption (such as interfering/synergistic relationships) for VOC mixtures with different polarities are accounted for in terms of interaction between the key variables (e.g., pore size distribution, adsorbent particle size, surface element compositions, and sorbent bed mass). Accordingly, the powdered P900 (0.212–0.6 mm: 150 mg) exhibits an adsorption capacity of 5.7 mg g−1 and a partition coefficient of 0.19 mol kg−1 Pa−1 for single-phase FA at the 10% BT level. Interestingly, its FA adsorption performance is synergistically improved in the presence of toluene (e.g., > 150%) in the early stage of adsorption (e.g., 10% BT), although their competition reduced its performance at 99% BT. The apparent synergistic trend in the early BT stage may possibly reflect diffusion resistance of the adsorbent (e.g., small particle size and developed ultra-micropore structure) and natural attributes of FA (e.g., low affinity and smaller kinetic diameter). The overall results of this study are expected to offer a better understanding of the mechanisms underlying the interactions between the mixed VOC system and microporous adsorbents.

Influence of P and C co-alloying on soft magnetic properties and crystallization behavior of FeSiBPCCu nanocrystalline alloys

In this study, multicomponent synergistic effects were adopted to enhance the glass-forming ability (GFA), processing window (PW), thermal stability, and soft magnetic properties (SMPs) of FeCuSiB nanocrystalline alloys (NAs) with high Fe and Cu contents via P and C co-alloying. The co-addition of P and C is beneficial for enhancing the GFA, expanding the PW, and increasing the crystallization resistance of the compound phases in present FeCuSiBPC alloys. Consequently, the Fe81.5Cu1.7Si3.8B9P3C1 alloy exhibited a large optimum TA window of up to 100 °C and a large tA window of 40 min for nanocrystallization. Crystallization kinetic analysis showed that the co-addition of P and C led to a high-frequency factor (v) in the precipitation of α-Fe crystals, which was related to the high nanocrystal density (Nd) of α-Fe. This result may be attributed to the nucleation of α-Fe by Cu and CuP clusters. Additionally, the co-addition of P and C increased the growth active energy (Ep) of the α-Fe crystals because of their larger atomic diffusion resistance. The high Nd and Ep values led to the formation of fine nanostructures and excellent SMPs in FeCuSiBPC alloys. Therefore, the Fe81.5Cu1.7Si3.8B9P3C1 NA obtained by annealing at 420 °C for 30 min exhibited excellent SMPs with a Bs of up to 1.78 T, a low Hc of 7.5 A/m, and a high μe of 9863 (@1kHz). This study provides technical and theoretical guidance for optimizing the composition and processability of NAs with high Fe and Cu contents, paving the way for mass production of high-performance soft magnetic NAs.

Experimental and simulation study on hygroscopic hydrogel-based thermal management of electronic device

With the increasing power of electronic devices, thermal management has become crucial for their operational efficiency and lifespan. In this work, we have demonstrated a sorption-based thermal management strategy enabled by hygroscopic hydrogel. The polyacrylamide (PAM) hydrogel impregnated with LiCl (PAM-LiCl) was attached to a silicon wafer. And Pt metal circuits were coated to the silicon wafer to measure the temperature variations under different heat flux densities. The results show that the hydrogel can effectively reduce the surface temperature. At a heating power of 0.3 W/cm2, the temperature control duration reached 30 min, with an average effective heat transfer coefficient of 65.5 W/(m2·K) and an effective heat storage density of 171 J/cm2. Additionally, we developed and validated a multiphysics model considering desorption and vapor diffusion within the hydrogel. Numerical results indicate that during the desorption cooling process, the surface heat transfer resistance and the internal diffusion resistance play a dominant role. Additionally, we analyzed the effects of material properties, structure parameters, and operating conditions on the thermal management performance. This study helps to understand the key points of sorption-based thermal management technology and guide the design and optimization of sorption-based thermal management system.

Investigation on the Hydrothermal Condition in Synthesis of Active Matrix from Metakaolin: Physicochemical Properties and Intrinsic Cracking Activities

The current trends in research and development of FCC catalyst is focused on the formulation of active matrices that serve as pre-crackers, with the objective of reducing the diffusional resistance of the longer chain hydrocarbon molecule in the feed. In this study, an aluminosilicate active matrix was synthesised from metakaolin using hydrothermal method. The experimental variables that were varied were hydrothermal temperature, in the range of 80 to 110 °C, and hydrothermal time, in the range of 12 to 72 hours, to investigate the best conditions for synthesising the active matrix. Subsequently, the active matrix was subjected to a series of analyses, including X-ray fluorescence, X-ray diffraction, N2 physisorption, NH3-temperature programmed desorption, Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetry, with the objective of determining its composition, crystal characteristics, surface characteristics, acidity, functional groups, material structure, and thermal characteristics. Additionally, the active matrix was tested for its intrinsic cracking activity using the micro activity test (MAT). The results indicate that the best temperature for hydrothermal synthesis of the active matrix is 80 °C. The active matrix synthesised with a heating time of 24 hours demonstrated the highest light cycle oil yield, reaching 38.9 wt%. Meanwhile, the active matrix synthesised at 48 hours exhibited the most favourable characteristics, with a specific surface area of 144.23 m2/g and a pore volume of 0.9933 cm3/g, as well as the highest cracking conversion of 70.0 wt%. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Enhancing thermo-mechanical and moisture properties of 3D-Printed concrete through recycled ultra-fine waste glass powder

This paper presents a novel approach to enhancing 3D printed concrete (3DPC) by incorporating ultra-fine glass powder (UFGP), focusing on its mechanical properties and high-temperature resistance. Investigation like fresh properties, basic physical properties, residual compressive strength after exposure to 400 °C and 800 °C, hygric properties such as water vapor diffusion resistance, liquid water transport, and moisture buffering capacity were performed the observe the effect of UFGP replacement ratio on 3DPC, which demonstrates significant improvements, highlighting the potential of UFGP to elevate 3DPCs’ performance. Results showed significant improvements, particularly with a 20% UFGP mix, which showed the lowest compressive strength loss (9.0% at 400 °C and 53.7% at 800 °C). Additionally, the water vapor diffusion resistance factor for the 20% UFGP mix was measured at 65.03. These results suggest that incorporating UFGP in 3DPC enhances thermal resilience and mechanical properties, offering a solution for high-temperature construction. This study contributes to sustainable construction by emphasizing the importance of mechanical resilience for structural integrity under extreme temperatures.

Mg and Fe co-loaded biochar prepared by microwave-synergized K2FeO4 of marine biomass for efficient CO2 capture: Performance assessment and mechanism exploration

To overcome the limitations of complex preparation and suboptimal performance of CO2 adsorbents, the present work synthesized a polymetallic oxide-loaded biochar (MgO·FeOx@biochar) with good performance in one step using a green and simple method of microwave-synergized K2FeO4. MgO·FeOx@biochar-700–10-0.1 with a hierarchical porous structure, abundant adsorption sites and well-distributed basic sites was obtained by optimizing the preparation parameters, which had a good CO2 trapping performance of 4.92 mol/kg with a retention rate of 83.01 % over 20 cycles, and exhibited good selectivity for O2 and N2. CO2 capture by MgO·FeOx@biochar was predominantly driven by chemical interaction between surface adsorption sites and CO2, supplemented by microporous filling. The adsorption kinetics revealed that the CO2 adsorption rate of MgO·FeOx@biochar was influenced by the combined effect of membrane diffusion resistance and intraparticle diffusion resistance. This study established a theoretical basis and technical insight for the environmentally friendly and efficient preparation of high-performance biochar-based CO2 adsorbents.

Imparting insoluble-soluble property to Cyt c by immobilizing Cyt c in UCST-pH dual responsive polymer for highly sensitive detection of phenol

Immobilization of enzymes in porous organic framework (POF) materials is popular strategy to stabilize enzymes. For such solid enzyme catalysis system, improving the catalytic efficiency is challenging due to the diffusion resistance from solid-liquid interface and inner pores. Here, UCST-pH dual responsive polymeric carrier (PEG-b-PAAm-b-P(GMA-co-AAc)) was synthesized to immobilize cytochrome c (Cyt c), which impart the reversibly insoluble-soluble property to the immobilized Cyt c. The PEG-b-PAAm-b-P(GMA-co-AAc) could serve as an insoluble-soluble matrix to fast and efficiently immobilize Cyt c via covalent attachment, achieving a remarkable 92 % loading efficiency within just 120 min. The obtained insoluble PEG-b-PAAm-b-P(GMA-co-AAc)-Cyt c micelles exhibited an improvement in thermal, pH stability and reusability. The completely soluble PEG-b-PAAm-b-P(GMA-co-AAc)-Cyt c conjugates accelerated substrate diffusion and then enhanced the catalytic efficiency. These excellent advantages led to low detection limit (1.99 μM), lower than the presently reported biosensors based on enzyme mimics in the colorimetric detection of phenol. This UCST-pH dual responsive window presents a new platform to efficiently control the immobilization and release of enzymes, which will achieve excellent stability and catalytic efficiency.

Photothermal Infrared Radiometry and Thermoreflectance-Unique Strategy for Thermal Transport Characterization of Nanolayers.

Thermal transport properties for the isotropic and anisotropic characterization of nanolayers have been a significant gap in the research over the last decade. Multiple studies have been close to determining the thermal conductivity, diffusivity, and boundary resistance between the layers. The methods detailed in this work involve non-contact frequency domain pump-probe thermoreflectance (FDTR) and photothermal radiometry (PTR) methods for the ultraprecise determination of in-plane and cross-plane thermal transport properties. The motivation of one of the works is the advantage of the use of amplitude (TR signal) as one of the input parameters along with the phase for the determination of thermal parameters. In this article, we present a unique strategy for measuring the thermal transport parameters of thin films, including cross-plane thermal diffusivity, in-plane thermal conductivity, and thermal boundary resistance as a comprehensively reviewed article. The results obtained for organic and inorganic thin films are presented. Precise ranges for the thermal conductivity can be across confidence intervals for material measurements between 0.5 and 60 W/m-K for multiple nanolayers. The presented strategy is based on frequency-resolved methods, which, in contrast to time-resolved methods, make it possible to measure volumetric-specific heat. It is worth adding that the presented strategy allows for accurate (the signal in both methods depends on cross-plane thermal conductivity and thermal boundary resistance) and precise measurement.