High Thermal Expansion Coefficient Research Articles

Synergistic Improvement of Flame Retardancy and Mechanical Properties of Epoxy/Benzoxazine/Aluminum Trihydrate Adhesive Composites.

Epoxy resin was mixed with benzoxazine resin and an aluminum trihydrate (ATH) additive to provide flame retardancy and good mechanical properties. The ATH was modified using three different silane coupling agents and then incorporated into a 60/40 epoxy/benzoxazine mixture. The effect of blending compositions and surface modification on the flame-retardant and mechanical properties of the composites was investigated by performing UL94, tensile, and single-lap shear tests. Additional measurements were conducted including thermal stability, storage modulus, and coefficient of thermal expansion (CTE) assessments. The mixtures containing more than 40 wt% benzoxazine revealed a UL94 V-1 rating with high thermal stability and low CTE. Mechanical properties including storage modulus, and tensile and shear strength, also increased in proportion to the benzoxazine content. Upon the addition of ATH to the 60/40 epoxy/benzoxazine mixture, a V-0 rating was achieved at 20 wt% ATH. The pure epoxy passed a V-0 rating by the addition of 50 wt% ATH. The lower mechanical properties at high ATH loading could have been improved by introducing a silane coupling agent to the ATH surface. The composites containing surface-modified ATH with epoxy silane revealed about three times higher tensile strength and one and a half times higher shear strength compared to the untreated ATH. The enhanced compatibility between the surface-modified ATH and the resin was confirmed by observing the fracture surface of the composites.

Effect of multi-component rare-earth doping on maintaining structure stability of RE2Zr2O7 (RE = La, Sm, Gd, Y, Yb) coatings under thermal cycling

Inspired by the high entropy effects of high-entropy components, a novel high-entropy rare-earth zirconate (La1/5Gd1/5Y1/5Sm1/5Yb1/5)2Zr2O7 (HEC-LZ) was designed and successfully synthesized in this work. In addition, two binary rare-earth doped zirconates (RE-LZ), (La1/3Sm1/3Yb1/3)2Zr2O7 (LSYZ) and (La1/3Gd1/3Y1/3)2Zr2O7 (LGYZ), were proposed using the same rare-earth elements for comparison. The thermal barrier coatings with LZ-based ceramic top layer were prepared by spray granulation, solid-phase synthesis and atmospheric plasma spraying techniques. The as-synthesized LZ-based ceramics are all dominated by the pyrochlore phase. Under 1000 °C, the thermal cycling performances of the three coatings were studied. The microstructure evolution and crack expansion during the failure process were investigated in detail. The strengthening mechanism and the cause of coating spallation are proposed in combination with mechanical properties and thermal matching analysis. The results showed that compared with the undoped LZ coating, the thermal shock life of LGYZ coating, LSYZ coating and HEC-LZ coating is improved by nearly 46%, 27% and 57%, respectively. Due to the characteristics of high randomness, HEC-LZ ceramic has a large lattice distortion than RE-LZ ceramics, resulting in a higher coefficient of thermal expansion and fracture toughness, which contributes to maintaining the structure stability of coatings under thermal stress.

Modification of Misfit-Layered Cathode Materials for Improving Electrocatalyic Activity in Reversible Protonic Ceramic Cells

In reversible protonic ceramic cells (RPCCs), due to their fast oxygen reaction kinetics, perovskite-structured cathode materials have been in the spotlight up to this point. However, such materials have some drawbacks such as low phase stability in humid atmospheres, high thermal expansion coefficient, and relatively low proton conductivity despite high electrocatalytic activities when used as steam-air electrodes. Hence, we suggest that novel misfit-layered structure Ca3Co4O9+δ (CCO)-based materials be used to overcome these technical issues with superior performance in RPCCs. Although CCO is a cobaltite-material, CCO has a similar thermal expansion coefficient as BZCYYb electrolyte’s (10‒12×10-6 K-1). Moreover, the plate-like morphology of the CCO-based materials are favorable for the introduction or emission of steam. Further, with alkali metal doping in Ca-site, CCO generates extra charge carrier species with the modified Co oxidation state, which results in high proton uptake and diffusion mechanism. Altogether, 5 mol% potassium-doped CCO-cells show great potential as a cathode material.

Experimental and Investigation of Heat Transfer for Radiator by Changing Composite (Bronze And Copper Oxide) Using Pin-Fin Apparatus

This paper discussed composite of bronze, copper oxide alloy and beryllium material and to evaluate the heat transfer properties through PIN FIN apparatus. Within the last few years there has been a rapid increase in the utilisation of Composite, particularly in the automobile industries, due to their high strength to weight ratio, high wear resistance, low density and low coefficient of thermal expansion. The advancements in the field of application make the study of their mechanical behaviour of utmost importance. In this present investigation, bronze and copper, beryllium composite were using Stir casting method. Finally investigate of bronze and copper, beryllium material and to evaluate the Mechanical properties of the model composite plate. Key Word: Copper; Radiator; Heat Transfer; Convection; Composition.

Lightweight diamond/Cu interface tuning for outstanding heat conduction

AbstractWith rapid developments in the field of very large‐scale integrated circuits, heat dissipation has emerged as a significant factor that restricts the high‐density integration of chips. Due to their high thermal conductivity and low thermal expansion coefficient, diamond/Cu composites have attracted considerable attention as a promising thermal management material. In this study, a surface tungsten carbide gradient layer coating of diamond particles has been realized using comprehensive magnetron sputtering technology and a heat treatment process. Diamond/Cu composites were prepared using high‐temperature and high‐pressure technology. The results show that, by adjusting the heat treatment process, tungsten carbide and di‐tungsten carbide are generated by an in situ reaction at the tungsten–diamond interface, and W–WC–W2C gradient layer‐coated diamond particles were obtained. The diamond/Cu composites were sintered by high‐temperature and high‐pressure technology, and the density of surface‐modified diamond/Cu composites was less than 4 g cm−3. The W–WC–W2C@diamond/Cu composites have a thermal diffusivity as high as 331 mm2 s−1, and their thermal expansion coefficient is as low as 1.76 × 10−6 K−1. The interface coherent structure of the gradient layer‐coated diamond/copper composite can effectively improve the interface heat transport efficiency.

Point-coated long-period fiber grating for temperature measurement.

In this paper, a temperature sensor based on a point-coated long-period fiber grating (PC-LPFG) is proposed and investigated. This structure is fabricated using a thermal filling method. The point-coating approach effectively increases the coupling efficiency between the sensing unit and the surrounding medium. The polymethyl methacrylate (PMMA), with high thermal optical coefficient (TOC) and thermal expansion coefficient (TEC), improves the temperature sensitivity of the PC-LPFG. Experimental results show that the temperature sensitivities of this sensor are 2.948 nm/°C and 6.717 nm/°C in the temperature ranges of 80.4-91°C and 91-97°C, respectively. The hot point-coating method of the PC-LPFG provides a new, to the best of our knowledge, approach to combining optic fiber sensors with high polymer materials.

Die-embedded packaging using Corning® multi-layered glass

Die-embedded (DE) packaging technologies in recent years have ventured into advanced packaging structures, such as fan-out wafer level packages (FOWLPs) or package-on-packages (PoPs). They offer higher density at lower costs, despite many challenges, such as the die-shift and warpage problems often observed during the molding process, caused by the high shrinkage and high coefficients of thermal expansion (CTEs) of the molding materials. This in turn makes it difficult to accurately mount the high-density fine-pitch bumps and adversely affects the overall yield, especially in processes using large-size substrates. Glass, known for its superior dimensional and thermal stability and its low or tunable CTEs, can be advantageous in reducing die-shift and warpages as opposed to other alternative material solutions for the molding process. In this paper, we propose a packaging solution based on a glass substrate incorporating a plurality of precisely dimensioned cavities, with a chip positioned in each cavity to prevent them from shifting during processing. Corning® Adaptive Formed Glass (AFG), a laminate glass with a unique clad/core/clad structure, allows for effectively forming cavities with high dimensional precision and positional accuracies as well as surface flatness through a wet etch process. Using a 0.5mm thick laminate Corning® AFG glass, we successfully designed and fabricated three types of DE packages with lab scale tools at Korea Electronics Technology Institute (KETI): single- and double-sided DE packages, and package-on-packages (POPs). High etching selectivity over 20:1, which was achieved by carefully designing the core and clad glass compositions, enabled a wet-etch cavity forming process with accurate cavity depths and flat bottom surfaces (< ± 2.5μm) with relative ease. A double-sided DE package with a total thickness of 600μm was fabricated with two 125μm-thick IC chips, one embedded on each side of the substrate, and connected by metallized through glass vias (TGVs). A POP measured at 5.1×5.1×1.27 mm3 was also successfully demonstrated by using two built-in double-sided DE packages joined by flip-chip bonding, equivalent to stacking four layers of conventional single-sided DE packages. The double-sided DE packages and POPs presented in this paper are believed to be the world’s first demonstration on glass. The work also manifests the immense potential of Corning® AFG glass in enabling higher density IC packaging and large-size panel-level (or wafer-level) packaging.

Corrosion and degradation mechanisms of high chromia refractory bricks in an entrained-flow gasifier: experimental and numerical analysis

As a crucial component of an opposed multi-burner (OMB) coal-water slurry gasifier, severe degradation of the refractory lining frequently results in costly operation delays. In this work, the morphology and damage evolution of the used high chromia refractory bricks in a gasifier were evaluated by experimental tests and numerical analysis to gain insight into the corrosion and degradation behavior of the refractory lining. The results indicated that the degradation of high chromia refractory bricks were mainly owing to the structural spalling caused by slag corrosion and thermal stress induced by temperature gradient. The stress cracks developed at the corroded interface provided a penetration pathway for slag and served as a sub-surface for further corrosion, resulting in additional corrosion and spalling. Furthermore, the formation of the composite spinel phase with a high thermal expansion coefficient also contributed to significant thermomechanical stress. The degradation behavior of high chromia refractory brick followed the “penetration-dissolution/reaction-spalling” mechanism. Based on experimental and numerical results, a conceptual model was developed to describe the progressive degradation mechanism of refractory, and several possible solutions were also suggested.

Highly sensitive fiber-optic temperature sensor with compact hybrid interferometers enhanced by the harmonic Vernier effect.

A compact fiber-optic temperature sensor with hybrid interferometers enhanced by the harmonic Vernier effect was proposed, which realized 36.9 times sensitization of the sensing Fabry-Perot interferometer (FPI). The hybrid interferometers configuration of the sensor consists of a FPI and a Michelson interferometer. The proposed sensor is fabricated by splicing the hole-assisted suspended-core fiber (HASCF) to the multi-mode fiber fused with the single-mode fiber, and filling polydimethylsiloxane (PDMS) into the air hole of HASCF. The high thermal expansion coefficient of PDMS improves the temperature sensitivity of the FPI. The harmonic Vernier effect eliminates the limitation of the free spectral range on the magnification factor by detecting the intersection response of internal envelopes, and realizes the secondary sensitization of the traditional Vernier effect. Combing the characteristics of HASCF, PDMS, and first-order harmonic Vernier effect, the sensor exhibits a high detection sensitivity of -19.22 nm/°C. The proposed sensor provides not only a design scheme for compact fiber-optic sensors, but also a new strategy to enhance the optical Vernier effect.

Thermal expansion coefficient of nonstoichiometric gadolinium zirconate: First-principles calculations and experimental study

A high thermal expansion coefficient (TEC) is highly desirable for a thermal barrier coating material to prolong the life of the entire coating system. The TECs of Gd2-xZr2+xO7+0.5x (x = 0, ±0.125, ±0.25, ±0.375) have been studied by first-principles calculations and solid-state reactions. Due to the strong bond energy and interatomic interaction force between Zr and O, and Gd3+ having a higher thermal diffusion coefficient and lower solid solubility, the TEC of a material with higher Gd3+ content and lower Zr4+ content is improved. Calculated results show that the highest Gd3+ content (x = −0.375) increases the TEC of Gd2-xZr2+xO7+0.5x from 7.26 × 10−6/K (x = 0.375) to 8.95 × 10−6/K (1500K). The Debye temperature decreases with increasing Gd3+ content. The experimental TEC is highest (11.593 × 10−6/K) at a content of x = −0.375, far exceeding that at x = 0.375 (10.690 × 10−6/K). The experimental results agree well with the calculated results. This work lays a foundation for obtaining rare-earth zirconate materials with outstanding thermal physical properties, and it provides a novel method for their creation.

Analysis of iron-chromium-aluminum samples exposed to accident conditions followed by quench in the QUENCH-19 experiment

The QUENCH-19 experiment was a first-of-its-kind full-bundle test simulating accident conditions followed by water quench on accident-tolerant fuel (ATF) cladding. A type of FeCrAl(Y) alloy, B136Y3, was developed at Oak Ridge National Laboratory and tested at the Karlsruhe Institute of Technology using Kanthal APM corner rods, a shroud, and Kanthal AF spacer grids. Testing conditions were similar to those in QUENCH-15—which tested ZIRLO cladding behavior—so that B136Y3 and ZIRLO cladding could be compared. QUENCH-19 consisted of an initial pre-oxidation heating followed by a transient. Then, a maximum power hold, which was not present in QUENCH-15, was executed to extend the heating period for the FeCrAl(Y) rods. Finally, a rapid water quench was executed that was similar to emergency core coolant system (ECCS) actuation. Compared with the ZIRLO rods in QUENCH-15, the bundle in QUENCH-19 released significantly less H2 (9.2 g vs. 47.6 g) and achieved a much lower maximum temperature (1455°C vs. 1880°C). Furthermore, no breakaway oxidation was observed in QUENCH-19. Metallographic mounts revealed that despite the symmetry of the setup, at elevations near the maximum temperature, cladding and thermocouples were heavily damaged, substantial melting and oxidation occurred, and the cladding underwent chemical interaction with the thermocouple sheaths. Additionally, the ZrO2 spacers detrimentally interacted with the cladding, leading to mixed oxide debris and the full destruction of some rods. Additional failure was found in certain cooler rods that may have risen due to the high thermal expansion coefficient of FeCrAl alloys. This paper presents an analysis of this work, which suggests that FeCrAl cladding can chemically survive anticipated loss-of-coolant accident events followed by rapid ECCS quench if the correct geometry and core design are present.

The formation of spinel CuxMn3-xO4 at 750 °C in the designed CuMn layers for solid oxide fuel cell applications

The Cu-Mn based spinel coatings without Cr show good application prospects due to their high conductivity and thermal expansion coefficient matching with metallic interconnectors. Based on the Cu-Mn-O phase diagram, the CuMn alloy layers with different Cu/Mn ratios were designed by electro-deposition and high energy micro-arc alloying (HEMAA) processes. The Mn-33Cu-17Co layer was prepared by HEMAA for thermal growth of the CuMn spinel oxides, and the fine-grained 430 layer was prepared by HEMAA as an interlayer at the interface between the 430 SS substrate and the coating. The microstructure and composition of the composite layers were analyzed. The results show that after oxidation treatment at 750 °C for 500 h, the oxide products of the Mn-33Cu-17Co layer were mainly cubic spinel Cu1.4Mn1.6O4 and CuO, which were different from those of the Mn-35Cu oxide layer, spinel Cu1.2Mn1.8O4 and Mn2O3. The aggregation of Cu-rich oxides was not found in the cross-section and on the top surface of the Mn-33Cu-17Co oxide layer, and the outer spinel layer was uniform and compact. The designed Mn-33Cu-17Co layers, Mn-35Cu layers and Mn1.5Cu1.5 layers showed good high temperature oxidation resistance and electrical conductivity.

Phase stability and thermophysical properties of CeO2-Re2O3 (Re[dbnd]Eu, Gd, Dy, Y, Er, Yb) co-stabilised zirconia

A series of 16 mol% CeO2-2 mol% Re2O3 co-stabilised zirconia (ZrO2) (16Ce4ReSZ, ReEu, Gd, Dy, Y, Er, Yb) ceramic materials were synthesised using a chemical coprecipitation– high-temperature roasting method. Their phase structure, high-temperature phase stability, mechanical properties, thermal conductivity and coefficient of thermal expansion (CTE) were investigated. The results show that the ZrO2 tetragonal phase co-stabilised by CeO2 and Re3+ with a smaller radius has better stability. The 16Ce4ReSZ (ReDy, Y, Er, Yb) materials have high fracture toughnesses, low thermal conductivities, and high CTE values. As the radius of the Re3+ ions decreases, the lattice energy increased, while the lattice distortion decreases, the CTE decreases slightly and the thermal conductivity of the material increases slightly. Owing to the high phase stability of 16Ce4YbSZ, its mechanical properties are best after 100 h of sintering at 1400 °C.

The modification and strengthening dual functionality of rare-earth oxide in La2O3-BaO-SiO2 glass for high temperature sealing application

In this paper, the modification and strengthening dual functionality of rare-earth oxide is authenticated by the effect La2O3/BaO on composition-structure-property correlations of new type La2O3-BaO-SiO2 (LBS) glass-ceramics sealing material with high softening point, high coefficient of thermal expansion and excellent high temperature resistivity. As the network modifier, the La2O3 can create more non-bridging oxygen than the BaO, resulting in the increase of Q0 and Q1 units and the decrease of Q2 and Q3 units in the La2O3-BaO-SiO2 glass according to Raman and 29Si Solid-State Nuclear Magnetic Resonance. The strengthening functionality of La2O3 is declared by Static 139La WURST-QCPMG NMR spectra that La3+ ions form La-O bonds with O2- ions in the glass structure and La3+ spectra widens slightly with the increasing of La2O3. Correspondingly, physical properties including Tg, Tc, ρ, and MV of La2O3-BaO-SiO2 glass gradually increase with increasment of effective cation field strength. The main crystal phase of LBS glass-ceramic transforms from Ba2Si3O8 to Ba5Si8O21 and furthur to Ba3Si5O13 phase with high coefficient of thermal expansion and there is not lanthanum-contained phase precipitation. The coefficients of thermal expansion (CTE) of LBS glass-ceramic increases from 12.48 × 10−6/℃ to 13.18 × 10−6/℃ (30–1000 ℃) and the softening temperature are between 1231.1 ℃ and 1305.1 ℃. The direct-current (DC) resistivity of the LBS glass-ceramics is higher 106 Ω·cm at a high temperature of 700 °C, which has good high-temperature electrical insulation. All in all, the high CTE, high Ts and high electrical insulation “Tri-high” properties of rare-earth oxide La2O3-BaO-SiO2 glass-ceramic will be an excellent candidate for solid oxide fuel cell, solid oxide electrolysis cell, oxygen sensors, and so on.

Ultra-low temperature solid-state synthesis of single-phase SrY2O4 for thermal-barrier-coating applications

Due to the thermal and chemical stability, SrY2O4 has a potential to be utilized as thermal barrier coatings materials. Unfortunately, the relative high synthesis temperature (> 1425 °C) of SrY2O4 leads to high energy consumption limits its industrial production. To address this issue, a novel and easy fabricating approach for single-phased SrY2O4 was explored at ultra-low temperature of 950 °C, in which isopropanol was used to disperse the powder slurry by ball milling. The XRD and high-resolution TEM results demonstrated that the obtained SrY2O4 possesses an anti-spinel orthorhombic crystal structure. In addition, SrY2O4 has good phase stability and high thermal expansion coefficient (11.06 × 10−6 K−1, RT ∼ 1200 °C) at high temperature, which implies that it is a good choice for thermal barrier coatings.

New class of high‐entropy rare‐earth niobates with high thermal expansion and oxygen insulation

AbstractTailoring the structure and properties of materials using the high‐entropy (HE) effect is of significant interest in the fields of environmental and thermal barrier coatings (TBCs). In this work, a new class of dense HE rare‐earth niobates was successfully prepared by a solid‐phase reaction method, including (Sm1/5Dy1/5Ho1/5Er1/5Yb1/5)NbO4 (5HERN), (Sm1/6Dy1/6Ho1/6Er1/6Yb1/6Lu1/6)NbO4 (6HERN), (Sm1/7Dy1/7Ho1/7Er1/7Yb1/7Lu1/7Gd1/7)NbO4 (7HERN), and (Sm1/8Dy1/8Ho1/8Er1/8Yb1/8Lu1/8Gd1/8Tm1/8)NbO4 (8HERN), along with eight single rare‐earth niobates (RENbO4, RE = Sm, Dy, Ho, Er, Yb, Lu, Gd, and Tm). X‐ray diffraction analysis showed that 5–8HERN are single‐phase solid solutions with a monoclinic structure (space group C12/c1). The thermal expansion coefficients of 7HERN and 8HERN exceed 11 × 10−6 K−1 at 1200°C and are much higher than those of the RENbO4 compositions (10.13–10.74 × 10−6 K−1) and other some HE rare‐earth oxides (10.27–10.87 × 10−6 K−1). Importantly, 5–8HERN have lower oxygen‐ion conductivity and higher activation energy than yttrium‐stabilized zirconia (YSZ) and the RENbO4 compositions. The oxygen‐ion conductivity of 5HERN (7.52 × 10−7 S cm−1, 900°C) was 105 times lower than that of YSZ (0.01 S cm−1, 750°C). The hardness of 5–8HERN is ∼7.81–8.46 GPa and these compositions have low intrinsic lattice thermal conductivity at high temperature (1.28–1.69 W m−1 K−1 at 900°C). The mechanism by which the HE effect improved the material properties was elucidated. Young's modulus, hardness, thermal expansion coefficient, and intrinsic lattice thermal conductivity are linearly related to the mass, size, and distortion degree of samples. In contrast, the oxygen‐ion conductivity depends on both the degrees of disorder and distortion and the oxygen‐ion vacancy concentration. Based on their overall performance, especially their high thermal expansion coefficients and excellent oxygen‐barrier performance, HE rare‐earth niobates show potential for further development as TBC materials.

Lowering thermal expansion of Mg with the enhanced strength by Ca alloying

The influence of Ca on the thermal expansion and mechanical properties of Mg are investigated in the present work. Alloying Ca is demonstrated to noticeably decrease the coefficient of thermal expansion (CTE) within a wide temperature interval and increase the strength of Mg at both as-cast and extruded state. A low CTE of ∼18.6 × 10−6 K−1 in combination with the high compressive yield strength of 262 MPa are achieved within the studied concentration interval. The reduced CTE of Mg–Ca alloys is found to closely correlate with the increased Debye temperature with Ca, which primarily emerges from the increased precipitation of Mg2Ca phase showing the relatively high melting point, elastic/shear moduli and low CTE. Similarly, the increased fraction of the eutectic lamellar structure consisting of Mg2Ca and α-Mg dominates the noticeable increase of strength of the as-cast Mg–Ca alloys. The lamellar structure is broken into fine particles dispersing in the matrix at extruded state, which in combination with the refined microstructure yields the dominated contribution to the increment of strength. The low thermal expansion and high strength achieved in the designed Mg–Ca alloys provide a feasible route for the development of advanced Mg alloys.

Polyaniline/Reduced Graphene Oxide/Carbon Nanotube Composites for Actuation-Based Sensing for Energy Storage

Until now, many carbon-based soft actuators with excellent performance have been developed, and various indicators of actuators are close to the limit. However, compared with the intelligence and versatility of natural biological muscles, soft actuators still have the shortcomings of single function and insufficient intelligence. Herein, polyaniline/reduced graphene oxide/carbon nanotube (PANI/RGO/CNT) composites are fully used to design and fabricate a smart gripper with a self-powered temperature-sensing function. First of all, the PANI/RGO/CNT composites have the characteristics of low coefficient of thermal expansion (CTE) and negative temperature resistivity. By cooperating with polymers with high CTE, a multifunctional bilayer actuator with a temperature-sensing function can be constructed with a temperature coefficient of resistance of 2364 ppm K–1. With the light irradiation (power density of 300 mW cm–2), the surface temperature, bending curvature, and resistance change of the actuator are as high as 48.8 °C, 0.86 cm–1, and −6.1%, respectively. Second, the PANI/RGO/CNT composite also possesses the advantage of large-area capacitance (165.8 mF cm–2). Thus, an integrated bilayer actuator with energy storage modules can be constructed through clever structural design and used as deformable supercapacitors. Finally, based on the similarity in structure and actuation mechanism of the multifunctional bilayer actuator and the integrated bilayer actuator, a smart gripper with a self-powered temperature-sensing function is proposed to provide real-time feedback of the change in temperature of the smart gripper as it grasps the object. The versatility of the smart gripper is achieved without increasing the complexity of the structure, demonstrating the advantages of the design concept of integrating sensing and energy storage in the design of soft actuators. The proposed PANI/RGO/CNT composites have great potential to be used in the fields of intelligent actuators, deformable supercapacitors, and artificial muscles.

Stress compensation based on interfacial nanostructures for stable perovskite solar cells

AbstractThe long‐term stability issue of halide perovskite solar cells hinders their commercialization. The residual stress–strain affects device stability, which is derived from the mismatched thermophysical and mechanical properties between adjacent layers. In this work, we introduced the Rb2CO3 layer at the interface of SnO2/perovskite with the hierarchy morphology of snowflake‐like microislands and dendritic nanostructures. With a suitable thermal expansion coefficient, the Rb2CO3 layer benefits the interfacial stress relaxation and results in a compressive stress–strain in the perovskite layer. Moreover, reduced nonradiative recombination losses and optimized band alignment were achieved. An enhancement of open‐circuit voltage from 1.087 to 1.153 V in the resultant device was witnessed, which led to power conversion efficiency (PCE) of 22.7% (active area of 0.08313 cm2) and 20.6% (1 cm2). Moreover, these devices retained 95% of its initial PCE under the maximum power point tracking (MPPT) after 2700 h. It suggests inorganic materials with high thermal expansion coefficients and specific nanostructures are promising candidates to optimize interfacial mechanics, which improves the operational stability of perovskite cells.

Synthesis and Properties of Silicon Carbide (Review)

Silicon carbide is an extremely hard material that exhibits exceptional corrosion resistance as well as thermal shock resistance. Its high mechanical properties determine the increased performance of materials based on it. The combination of high thermal conductivity and low thermal expansion coefficient determines the stability of silicon carbide at high heating rates and under stationary thermal conditions. To date, significant progress has been made in the development of methods for the synthesis of various materials based on silicon carbide. The main synthesis methods that scientists use in their research are the sol-gel method, sintering, pyrolysis, microwave synthesis, chemical vapor deposition, etc. The use of "green" techniques in the synthesis of SiC has gained wide popularity due to environmental friendliness, renewability, and ease of implementation. This review analyzes modern research in the field of silicon carbide synthesis published in peer-reviewed professional journals.