Al Layer Research Articles

Enhancing photo-response performance through ultrathin Al2O3 modification at the p-SnO2:Al/n-GaN heterojunction interface

We report on photoconductive and p-n heterojunction ultraviolet (UV) photodetectors based on p-type Al-doped SnO2 (p-SnO2:Al) thin films. We investigated the structural, optical, and electrical properties of Al-doped SnO2 thin films prepared using sol-gel methods, with our results being strongly supported by first-principles calculations. To achieve a self-powered photodetector device at zero bias, we fabricated p-SnO2:Al thin film on an n-GaN layer to form a p-n heterojunction. The responsivity of the p-n heterojunction UV detector, measured at zero bias, is 0.05 A/W, indicating good rectification properties. In order to improve device performance, a p-n heterojunction with a passivation layer was formed by inserting an ultrathin Al2O3 layer between the n-GaN layer and the p-SnO2:Al layer. With this change, the device's responsivity was 0.44 A/W at 350 nm at zero bias, roughly 10 times better than the detector without the Al2O3 passivation layer. The insertion of an ultrathin Al2O3 layer, which increases the efficiency of carrier separation on the SnO2 side while lowering the rate of carrier recombination at the interface, is responsible for the increased light responsivity performance.

Achieving high sheet resistance and near-zero temperature coefficient of resistance in NiCr film resistors by Al interlayers

Thin film resistive materials with low temperature coefficients of resistance (TCR) and high sheet resistances are essential for various electronic applications, such as embedded resistors. In this study, Al inserting layers and NiCr resistive layers were sequentially deposited on alumina ceramic substrates via DC magnetron sputtering to fabricate Al/NiCr bilayer resistive materials. The electrical properties of the bilayer films were adjusted by varying the thicknesses of the Al inserting layers and annealing conditions. When the thickness of the Al inserting layer varied from 5 to 7.5 nm, and post-annealing treatments ranging from 200℃ to 400℃ were applied, evident Al-NiCr interdiffusion occurred, forming intermediate layers at the interfaces and oxides on the film surfaces. A mixture of partial crystalline phases and amorphous phases was also observed in the cross-sectional high-resolution transmission electron microscope (HRTEM) images. The formation of intermediate layers and surface oxides and the balance between partial crystalline phases and amorphous phases collectively enhanced the electrical performance of bilayer film resistors, achieving thin film resistors with a remarkably low TCR of −6.61 ppm/K and a sheet resistance of up to 265.95 Ω/sq. By rational design of Al layers, NiCr layers and thermal treatment, thin film resistors with near zero TCRs and extremely wide sheet resistance range of 93.34–1439.01 Ω/sq can be obtained.

Development of Metal-Oxide-Metal Micro-Well Array Biosensors for Highly Sensitive Detection of Covid-19

Biosensors play a crucial role in various fields, including medical diagnostics, environmental monitoring, and food safety. Enhancing the sensitivity of biosensors is essential for improving their performance and reliability. One effective approach to achieve this goal is by reducing the distance of electrodes, a parameter that significantly influences the sensor's response. Employing vertical structures to reduce electrode gaps offers several advantages. the heightened controllability of vertical structures facilitates easy adjustments to element size and shape, catering to specific application requirements and maximizing sensor performance. The choice of vertical structures presents a more accessible, flexible, and cost-effective solution from a manufacturing standpoint, particularly for large-scale sensor production.On the other hands, DNA testing plays a pivotal role in the context of COVID-19, demonstrating its profound significance in the identification, monitoring, and management of the virus. Through the analysis of genetic material, particularly RNA in the case of COVID-19, DNA testing enables accurate and timely diagnosis of infections. This precision is instrumental in differentiating the virus from other respiratory illnesses, facilitating early intervention and containment measures. Moreover, the genetic insights garnered from DNA testing contribute to a better understanding of the virus's behavior, mutations, and potential therapeutic targets, thereby informing public health strategies and vaccine development. The integration of DNA testing in the comprehensive approach to combating COVID-19 underscores its indispensable role in mitigating the impact of the pandemic on global health.In this study, we present the development of a novel biosensor based microwell array structure. The fabrication process employed a layer-by-layer method. To be brief, a 4-inch silicon wafer with a 300 nm thick thermal SiO2 was cleaned in acetone, isopropanol, and water. Subsequently, the bottom electrode was deposited by E-gun evaporator followed by a lift-off process. An extremely thin 45nm aluminum oxide layer was deposited by Atomic Layer Deposition (ALD). Then, a 100nm gold layer was deposited as the top electrode by E-gun. Finally, conclude the fabrication by defining the sensing area of the microwell array through Lithography and several etching steps.For the DNA immobilization process, the Covid-probe ssDNA was incubated with the biosensor at 4℃ within the PDMS wells overnight, followed by rinsed 3 times. And 1 uM Covid-target ssDNA was incubated after immobilization of probe DNA. The condition for the reaction of target and probe was 1 hour at room temperature, followed by rinsed 3 times in DI water.The detection was achieved using a combination of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), collectively offering a comprehensive approach for accurate and reliable measurements. The electrolyte consists of 1 mM KCl solution as supporting electrolytes and 5 mM ferricyanide/ferrocyanide as redox pair. The Rct charge transfer resistance of bare device is around 1320 Ohm due to the small sensing area of around 500 * 500 um2. After incubation with the probe DNA, the Rct is around 2150 Ohm indicating that the probe DNA binds to the Au surface successfully. Target DNA was quantitatively measured over a wide concentration range, spanning from 10 pM to 10 nM. The Rct variance from 2260 to 4970 Ohm.Our results demonstrate the biosensor's exceptional performance in terms of sensitivity and dynamic range, showcasing its potential application in the early and accurate diagnosis of Covid-19. The micro-well array biosensor, with its unique design and integrated electrochemical measurement strategy, holds promise for future advancements in point-of-care diagnostics and environmental monitoring. Figure 1

Why Do Lithium-Ion Batteries Fail – a Case Study

Lithium-ion batteries are everywhere – phones, laptops, cars, and many more. With their increased usage, battery failure incidents have also become more common. In this talk, I will discuss a failure mode that frequently occurs in consumer electronics containing pouch cells, referred to as “pouch grounding”. As the name suggests, this failure occurs when the aluminum layer of the pouch contacts a component surrounding that is connected to the negative electrode of the battery, which serves as the grounding source. Effects of temperature and humidity on the pouch grounding failure will be discussed along with cell teardown analysis to reveal the mechanism. This talk will be focused on introducing industry level understanding of lithium-ion battery failures and how industry and academia can collaborate to enhance the technology further.

FLAx‐REinforced Aluminum (FLARE): A Bio‐Based Fiber Metal Laminate Alternative Combining Impact Resistance and Vibration Damping

Fiber metal laminates (FMLs) have mainly been used in aerospace applications with synthetic fibers. To improve their environmental credentials and address issues regarding the end‐of‐life of these materials, a shift to FMLs based on natural fibers can be a promising course of action. However, regarding them as conventional FMLs overlook some of the unique benefits of natural fibers. Therefore, this study pioneers the examination of FLAx‐REinforced aluminum (FLARE) for its combined impact resistance and vibration damping. Dynamic mechanical analysis and vibration beam tests demonstrate that the metallic layer predominantly influences the damping behavior of FLARE. The loss factor notably decreases with aluminum addition (by 80% compared to the flax composite), approximated via an inverse mixture rule. Low‐velocity impact tests highlight the role of aluminum layers in energy absorption and the composite strength as a critical factor in impact resistance. FLARE exhibits 25% less specific energy absorption compared to its glass fiber counterpart. A quasi‐static analytical model suggests the potential of FLARE for practical applications. With its balance of properties and considering its potential advantages at end‐of‐life, allowing recycling of aluminum, and its expected lower carbon footprint, FLARE renders potential beyond the aerospace sector, e.g., in other forms of transportation.

Shear behavior of Cu/Al/Cu trilayered composites prepared by high-temperature oxygen-free rolling

The interfacial microstructure, interfacial shear properties, and shear fracture morphology of Cu/Al/Cu trilayered composites prepared by high-temperature oxygen-free rolling were studied, and the interfacial shear fracture mechanism was revealed. The results showed that the Cu/Al/Cu trilayered composites have a good metallurgical bonding interface. The interfacial microstructure is composed of Al2Cu, AlCu, and Al4Cu9. The intermetallics (IMCs) parallel to the rolling direction show discontinuous distribution, while the IMCs perpendicular to the rolling direction have mainly continuous distribution and occasional discontinuous distribution. The interfacial shear strength at room temperature can reach 68 MPa, and when the test temperature rises to 350 °C, the interfacial shear strength drops sharply to 16.9 MPa. The interfacial shear fracture mainly occurs in the low-strength Al layer due to the good metallurgical bonding interface. The IMCs near the shear fracture exhibit clear signs of cracking, and there is a phenomenon where the Cu layer embeds into the Al layer in a "sawtooth" shape. Meanwhile, shear fracture also occurs in the IMCs layer, and a small amount of Al will attach to the surface of the IMCs. However, the high bonding strength resulting from the excellent metallurgical bonding of the interface makes this type of shear fracture rare. The shear fracture of Cu/Al/Cu trilayered composites is mainly dominated by the fracture of the low-strength Al layer and the occasional fracture of the IMCs.

New insights into aluminium anodizing in phosphonic acid

Aluminium anodizing in phosphonic acid is known to produce anodic aluminium oxide (AAO) honeycomb structures with large interpore distances. However, detailed information on two-stage anodizing in phosphonic acid and annealing conditions required for the crystallization of AAO cell walls have not been reported yet. Here, the kinetics of aluminium anodizing in 1 M phosphonic acid and the thermal behaviour of the resulting AAO have been studied in detail. The apparent activation energy of aluminium anodizing is 65 kJ mol–1 and the AAO growth rate reaches 15 µm h–1 before oxide “burning”. A universal approach for stable two-stage anodizing at high voltages allowing to prevent porous structure rearrangement in the upper part of AAO is proposed. It involves the preliminary formation of a dense barrier alumina layer by anodizing in a weak acid electrolyte before the second anodizing step in phosphonic acid. The crystallization pathways of AAO obtained in phosphonic acid electrolyte are revealed based on differential scanning calorimetry, X-ray diffraction, and solid-state nuclear magnetic resonance techniques. The designed annealing program allows one to preserve the honeycomb porous structure after the crystallization of AAO in corundum at 1310 °C for 60 h. AAO obtained in phosphonic acid possesses high thermal stability and, thus, is promising as a support for gas sensors and fuel cells.

Observation and characterization of titanium-like nano-filament in TiO2 memristor using superconducting electrode(s) and Andreev spectroscopy

A thin TiO2 semiconductor film embedded between two metal electrodes works as a memristor after being formed by soft breakdown. The forming creates a nano-filament that penetrates through the poorly conducting TiO2 film and connects the electrodes conductively. While previous works characterized the nano-filament properties (shape, composition, and resistivity) by electron microscopy techniques, we present a characterization by electrical measurements. In a typical memristor, both electrodes are made of normal metals. We study the metal/TiO2/metal memristors with a bottom electrode made of a superconducting NbN layer and a top electrode made of a normal (Pt) or superconducting (Nb) metal. The nano-filament connecting the electrodes touches the bottom electrode as a point contact, thus allowing us to perform point-contact Andreev reflection spectroscopy of the NbN superconductor. The spectra, measured below the critical temperature (15 K) of NbN, are analyzed theoretically. The analysis reveals the presence of one nano-filament and determines the nano-filament resistance, Sharvin resistance of the point contact, and Maxwell resistance of the electrodes. Moreover, it shows that the nano-filament is a conical-shaped Ti-like metal point contact with a tip diameter of ∼3–5 nm, Fermi velocity of 2×106m/s, and low-temperature resistivity of ∼10−8–10−7Ωm. Thus, the nano-filament in our device is not the Ti4O7 phase observed in previous works. Remarkably, the point contact spectrum of the superconducting NbN layer shows the Andreev peak typical for ballistic transport. This is because the point contact probes the NbN layer through a thin Al layer that mimics superconductivity of NbN via the proximity effect and eliminates the effects of tunneling and disorder.

Influence of annealing on the interfacial structure, recrystallization behaviour, and texture evolution of hot extruded Mg/Al laminated composites

The hot extrusion process is ideal for Mg/Al laminated materials; however, there is limited research on annealing for hot extruded Mg/Al laminated composites. In this study, Mg/Al composite tubes were prepared using the direct extrusion-shear deformation (DESD) process. The morphology of the Mg/Al interface at different annealing temperatures was investigated using scanning electron microscopy (SEM). As the annealing temperature increases, the bonding layer thickens, and the number of intermetallic compounds (IMCs) increases. Most of the IMCs tend to grow in a columnar manner perpendicular to the interface bonding layer. The β-Al3Mg2 layer is notably thicker than the γ-Al12Mg17 layer, attributable to the lower diffusion activation energy of β-Al3Mg2. The microstructure and texture evolution of the interfacial region were analyzed using backscattered electron diffraction (EBSD). The results show that the local average misorientation (LAM) within the Al layer is higher than that within the Mg layer, suggesting that the Al layer undergoes more significant plastic deformation and accumulates more strain energy than the Mg layer. The static recrystallization (SRX) fraction of the Mg layer is higher than that of the Al layer. However, The SRX proportion of Mg decreases with increasing annealing temperature due to secondary recrystallization. The annealing temperature significantly affects the grain orientation. As the annealing temperature increases, the deformation texture (S, Brass) of the Al layer gradually transitions to the recrystallization texture (Cube) and finally forms {123}<102> texture.

Formation of Through-Hole Porous Anodic Aluminum Oxide Layer Locally with 3D Printed Solution Flow Type Microdroplet Cell

In this study, a 3D-prinited solution-flow type microdroplet cell (SF-MDC) is employed as a new technique for the fabrication of porous anodic aluminum oxide (AAO) layer using oxalic acid electrolyte on aluminum. The surface morphology of the porous AAO film was characterized by a scanning electron microscope. The aim of this study was to fabricate a through-hole porous alumina layer in a single step anodizing process and to investigate the influence of anodized voltages and scanning speeds on the thickness and pore structure of alumina layer. The results showed that the pore diameter and interpore distance were directly proportional to the anodizing voltage. The thicknesses of formed AAO films were found to be 35.5, 50.7, and 81.6 μm at scanning speeds of 10, 5, and 2.5 μms−1, respectively. Through-hole porous AAO was successfully fabricated at room temperature without chemical etching. The SF-MDC fabrication technique is proposed as an environmentally attractive and suitable process for the fabrication of porous AAO layers.

An innovative approach for overcoming challenges in the stacked extrusion forming of Mg/Al composite plates

This study successfully produced Mg/Al composite plates with Cu transition layer, thus overcoming the limitations of traditional stacked extrusion methods in achieving satisfactory bonding of Mg/Al laminates. The relationship between the microstructure and mechanical properties of composite plates under three extrusion temperatures was revealed, and the deformation process and failure modes of composite plates were investigated. Microstructure observations revealed that the Cu layer exhibited a discontinuous distribution characteristic, and its thicker area effectively impeded the diffusion of Mg and Al elements, thus inhibiting the formation of Mg-Al intermetallic compounds (IMCs). The extrusion temperature did not significantly affect the distribution of the precipitates and texture in the Mg/Al layers. The grain size of the Mg layer showed a growing tendency with rising extrusion temperature, while that of the Al layer remained relatively constant. Mechanical results indicated that the strength of the composite plates decreased as the extrusion temperature increased, which was attributed to the weakening of fine grain strengthening in the Mg layer and dislocation strengthening in the Al layer. Additionally, higher extrusion temperature markedly reduced the elongation of the composite plate, potentially due to accelerated element diffusion at the interface and the discontinuous distribution of the Cu layer, resulting in significant enrichment of IMCs. The Mg-Cu IMCs accumulated and formed in the thicker Cu layer areas, along with Mg-Al IMCs formed in the weaker Cu layer areas, served as crack sources, resulting in cracking of the composite plate during the tensile and eventual failure.

Fabrication of composite nanostructures for impedance biosensors using anodic aluminum oxide templates and carbon nanotubes

A hybrid material consisting of an array of vertically ordered carbon nanotubes (CNTs) in porous anodic alumina was fabricated directly on oxidized Si substrates. Individual CNTs with vertical orientation were grown using the catalyst Ni nanoparticles (NPs) embedded in the pore walls of a thin template based on porous anodic alumina with a pore diameter of 40 ± 5 nm. The initial film was a two-layer Ti-Al structure on a Si/SiO2 substrate. A vertically oriented porous structure was formed by anodizing the Al layer. Electrochemical deposition was used to form the catalyst Ni-NPs with dimensions of 30 ± 5 nm. CNTs were synthesized by high-temperature chemical vapor deposition. Scanning and transmission electron microscopy, Raman spectroscopy, and X-ray diffraction were used to analyze the surface morphology and microstructure of the composite nanostructures. The CNT length was (0.6–1.5) μm, and the CNT spacing was 110 ± 10 nm. It is expected that the resulting structure will serve as a basis for the development of CNT-based electrodes for electrochemical impedance biosensors. Electrochemical impedance spectroscopy was used for the electrochemical characterization of the fabricated CNT-based electrodes. The results showed that the CNT-based electrodes are characterized by improved electron transfer kinetics.

Mechanical properties of layered composites based on AA1050 and AA5056 aluminum alloys produced by WAAM technology

Abstract The possibility of producing layered aluminum materials using wire-arc additive manufacturing (WAAM) technology has been investigated. Deformation characteristics of composites based on AA1050 and AA5056 aluminum alloys are considered. Mechanical tests of specimens with different orientations of AA1050 layers in AA5056 alloy matrix are presented. The results are analysed in the light of the structural characteristics of the composites.

Experimental and numerical investigation of the solid cold-welding properties of the APB process of Al/Cu bulk composites

AbstractNowadays, the use of bimetallic laminates with special capabilities is increasing and has experienced high growth. These properties include high mechanical properties, corrosion resistance, lightweight, and thermal stability. Among the technologies of multilayer composite materials, Accumulative Press Bonding (APB) as a solid-phased method of welding is one of the most common techniques for the production of multilayer composites. One of the most important aims for this choice is the press pressure, which can create a strong and suitable mechanical connection between produced metal layer components. In this study, the APB method has been used to produce bimetal aluminum/copper bulk composites as its novelty for the first time. After that, the effect of pressing parameters such as strain and number of layers on the stress distribution has been investigated. The shear stress among the layers reached 4 MPa for the samples with eight layers which is a good condition to generate a successful bonding. With increasing the thickness reduction ratio, the stress applied to the layers has also increased. As the thickness decreases, the interlayer shear stresses also increase which leads to a better bonding between layers. With increasing the thickness reduction ratio, the amount of layers sinking in each other was greater than before, which led to the crushing of copper layers along the entire length of the sample. During the process, as the number of passes increased, the volume of virgin material in the direction of the press rose, which led to increased compaction and better adhesion of Al and Cu layers to each other. The bonding strength enhances from 47 to 95 N for samples manufactured with one and four cycles of APB due to the increment of virgin metal normal to the pressing direction showing a 102% enhancement.

Thermodynamic model for a rocket engine cycle

In an era marked by the burgeoning popularity of space stations among both developing and developed nations, the demand for rockets has surged at an unprecedented pace. This meteoric rise in rocket usage has brought to the forefront a critical challenge: the efficient cooling of rocket engines. To address this issue, engineers have explored innovative solutions. One highly promising approach involves the incorporation of fuel-conducting pipes within the walls of the engine, utilizing the cooling properties of the circulating fuel to counteract the intense heat generated during combustion. Additionally, engineers have successfully employed a protective layer of aluminum oxide on the engines inner walls to enhance thermal insulation. These solutions, however, are not one-size-fits-all; they must be tailored to account for engine reusability and mass. Nevertheless, the combined use of internal fuel pipes and aluminum oxide coating has emerged as an exceptionally cost-effective and efficient method to mitigate the damage caused by heat during fuel combustion. This ground-breaking cooling strategy holds the potential to revolutionize all liquid rocket engines, offering a sustainable and reliable solution as the worlds interest in space exploration continues to soar.

Solution process of graphene-induced ohmic contact between the metal and AlGaN/GaN for hemts application

This work demonstrates an AlGaN/GaN high electron mobility transistor (HEMT) with Cr/Graphene ohmic contacts constructed without heat treatment. The Cr/Graphene ohmic contact was fabricated using a spray-coated graphene nanoflakes solution and electron-beam-evaporated Cr. This method does not require a high-temperature annealing step in conventional Ti/Al/Ni/Au ohmic contact. It is suggested that the Cr/graphene combination acts similarly to a doped n-type semiconductor in contact with AlGaN/GaN heterostructures, enabling carrier transport to the AlGaN layer. The investigated Au/Cr/ Graphene/AlGaN/GaN HEMT device exhibits ohmic drain characteristics in the range of -4 V to 4 V of drain-source voltage with a calculated contact resistance density of 2.5 mΩcm2. Our results have important implications for the fabrication and manufacturing of AlGaN/GaN-based microelectronic and optoelectronic devices/sensors of the future.

Joining of Copper and Aluminum Alloy A6061 Plates at Edges by High-Speed Sliding with Compression

By using the joined or welded materials of dissimilar metals, the characteristics and performance of products and parts can be improved. The combination of copper and aluminum is difficult to weld. In this study, the impact joining of copper C1100 and aluminum alloy A6061-T6 plates at the edges was investigated to explore the appropriate joining conditions. The plates are joined with newly created surfaces generated by the high-speed compressive deformation with sliding motion. The shape near the interface was a tapered trapezoid with a flat top. The joining length in the plate thickness direction was shorter than the plate thickness, and notches were observed near both plate surfaces. The length became slightly longer by setting a larger top width of the C1100 plate than that of A6061-T6. The joint efficiency increased by approximately 10%. Applying the emery paper finish to the surface of the plate eliminated the non-joining result in multiple experiments. The finishing direction is effective only in the longitudinal direction of the plate. In the tensile test on the dumbbell-type specimen with reduced thickness to eliminate notches, most results showed a fracture at the C1100 portion. The estimated temperature rise of the C1100 is more than about 250 K during the impact deformation. Hence, the strength of the A6061-T6 becomes lower than that of C1100 during the process, and the softened layer of aluminum comes out under pressure, resulting in good joining performance.

Elucidating the effect of whiskers on microstructural, mechanical and wear properties of ceramic-metal composites for sports venues applications

Ceramic whiskers reinforced composites are widely used in electrical, medical, and constructional applications due to their desirable strengths, hardness, and wear characteristics. In this study, to examine the wear and friction characteristics, the pressureless infiltrated Cu–SiC composites with different content of SiC whiskers were roll bonded to Al layer. According to SEM images, the SiC whiskers were distributed across the microstructure although they were aligned along rolling direction. Incorporation of SiC whiskers to Cu matrix led to rise of composites’ strengths, young moduli, and hardness values. The measured values of Al and Cu–SiC layers increased from 50 HV to 135 HV in Al/Cu–SiC (5 wt%) to 57 HV and 159 HV in Al/Cu–SiC (15 wt%). Ductile type of fracture along with dimples, delamination, and debonding of whiskers appeared on fracture surfaces. However, more debonding of SiC whiskers was observed as SiC content increased. Accordingly, mass loss decreased and less adhesive wear mechanism was observed. The mass loss decreased from 6.3 mg in Al/Cu–SiC (5 wt%) to 5.2 mg in Al/Cu–SiC (15 wt%).

Design of Acetaldehyde Gas Sensor Based on Piezoelectric Multilayer Microelectromechanical System Resonator.

Acetaldehyde is a volatile organic compound that can cause damage at the cellular and genomic levels. The monitoring of acetaldehyde gas at low concentrations requires fast-response and low-cost sensors. Herein, we propose the design of an acetaldehyde gas sensor based on a low-cost Microelectromechanical System (MEMS) process. This sensor is formed by a single-clamped piezoelectric multilayer resonator (3000 × 1000 × 52.2 µm) with a simple operating principle and easy signal processing. This resonator uses a zinc oxide piezoelectric layer (1 µm thick) and a sensing film of titanium oxide (1 µm thick). In addition, the resonator uses a support layer of 304 stainless steel (50 µm thick) and two aluminum layers (100 nm thick). Analytical and Finite-Element Method (FEM) models are developed to predict the mechanical behavior of the gas sensor, considering the influence of the different layers of the resonator. The analytical results agree well with respect to the FEM model results. The gas sensor has a first bending frequency of 4722.4 Hz and a sensitivity of 8.22 kHz/g. A minimum detectable concentration of acetaldehyde of 102 ppm can be detected with the proposed sensor. This gas sensor has a linear behavior to detect different acetaldehyde concentrations using the frequency shifts of its multilayer resonator. The gas sensor design offers advantages such as small size, a light weight, and cost-efficient fabrication.

Experimental study of a novel Radiative cooling-Dual phase change material roof under hot summer and warm winter climate

In hot summer and warm winter climates, phase change materials (PCMs), with their ability to absorb and store thermal energy, can effectively reduce indoor temperature fluctuations and lower cooling loads when applied to roofs. Therefore, this study proposes a novel Radiative cooling-Dual phase change material (RC-DPCM) roof and conducts experimental research on its regulation of indoor and outdoor thermal environments. This energy-efficient roof integrates radiative sky cooling with PCM latent heat storage technologies within a compact building envelope. The innovative dual-PCM configuration can store heat from both indoor sources and outdoor solar radiation during the day through integrated PCM layers. At night, radiative cooling materials emit heat to the deep universe, helping the PCM layers complete solidification. The thermal performance of the RC-DPCM roof was tested in hot summer and warm winter climates compared to other roof designs: a single layer of aluminum (AL) roof, the Aluminum-Thermal insulation (AL-TH) roof, the Radiative cooling (RC) roof, the Radiative cooling-Outside phase change materials (RC-OPCM) roof, and the Radiative cooling-Inside phase change materials (RC-IPCM) roof. Results showed that the RC-DPCM roof significantly improved indoor thermal comfort and efficiency. Compared with the AL roof, the RC-DPCM roof reduced the average indoor temperature by 1.13 °C (or 2.49 °C during working hours) and continuously dissipated heat from the indoor environment to the ambient environment, reducing the cooling load. Additionally, the RC-DPCM roof achieved a 172.9 % average cooling load reduction during working hours, outperforming other roofs, thus demonstrating its potential as an innovative solution for sustainable and energy-efficient buildings. The RC-DPCM roof effectively reduced peak indoor temperatures and cooling load, demonstrating its potential as an innovative solution for sustainable and energy-efficient buildings.