Strong Thermal Stability Research Articles

An investigation of various properties of hybrid bricks using Natural fibers and waste fiber-based materials

Air pollution is increasing daily, causing global warming and many environmental issues, and it is also the cause of many diseases. According to many reports, brick kilns play a major role in the emission of black carbon that causes air pollution. It is necessary to find another way to produce bricks. The trend these days is to increase applications of natural fibers and eco-friendly materials and to reuse waste materials to control pollution. Synthetic and chemical materials are also causes of pollution, diseases, and even the deaths of many people. In this direction, eco-friendly materials were used to produce bricks. Abaca fiber, Pinus-Roxburghi leaves, fiber, wood, wheat straw, animal dung, sand, cement, phenolic resin, and gypsum were used in various percentages to create novel brick. In the investigation, it was discovered that hybrid natural fiber-based bricks had strong physical-mechanical, mechanical-chemical, and thermal stability properties, were light in weight, and had good sound absorption capabilities. Significant improvement of has been identified, AB-4 Brick shows the maximum porosity with 42.5% improvement as compared to AB-1 brick.

Facile and eco-friendly synthesis of hydrogen bonding-rich bio-based bisbenzoxazine resins with low surface free energy, strong adhesion strength and high thermal stability

A facile and sustainable synthetic strategy has been designed to achieve a series of hydrogen bonding-rich bio-benzoxazine resins possessing a set of properties that are highly desirable in industrial applications.

Open-air, green-solvent processed organic solar cells with efficiency approaching 18% and exceptional stability

H75-2F, a fluorinated cathode material, boosts organic solar cell efficiency, achieving 19.44% PCE in controlled conditions and 17.78% with open-air green-solvent processing, while offering strong thermal and moisture stability.

Application of chelation effect in improving the triple properties of K2SiF6Mn4+ phosphors through composite modification

Mn4+-doped fluoride phosphors are limited by their poor moisture resistance in practical applications of white light-emitting diodes (WLEDs). Herein, a new red light-emitting phosphor KSF:MnK2SiF6:Mn4+ was synthesized based on a novel strategy combining surface treatment with hexamethylene tetramine (HMTA) and coating with a matrix, hereafter referred to as P-KSF:Mn. Given the formation of the coordination bond between N and Mn4+ and the strong hydrogen bond between N and F in the shell after the protonation of HMTA, a dense and firm shell of rare Mn4+ formed on the sample surface. P-KSF:Mn showed strong emission, waterproof property and luminescent thermal stability, and its fluorescence intensity was 1.81 times that of KSF:Mn. After soaking in water for 90 d, the fluorescence intensity of P-KSF:Mn was 90.7 % of the initial value. The integrated fluorescence intensity at 200 °C was approximately 416 % of the initial value at 25 °C. The strong luminous thermal stability was supported by strong negative thermal quenching (NTQ), which is explained by the phonon induction mechanism. The WLED prototype assembled with P-KSF:Mn emitted warm white light with correlated color temperature (CCT) = 3112 K, color rendering index (CRI) = 90.7, and luminous efficiency (LE) = 119 lm/W. The results show that P-KSF:Mn is a potential candidate for applications in the field of warm WLEDs.

A dual-purpose separator employing phosphine oxide with metal hydroxide incorporation onto polyethylene matrix to improve interfacial stability and safety of high nickel concentration lithium-ion batteries

In recent years, there has been considerable interest in high nickel concentration oxide batteries, typically denoted as high-Ni NMC, thanks to the substantial specific capacity (≤200 mAhg-1) and energy density. Nevertheless, the high-Ni NMC battery often encounters challenges related to interfacial problems and fire concerns stemming from the reduction of nickel (Ni) during electrochemical cycling. Herein, a dual-purpose separator incorporating Mg(OH)2 into dimethoxymethyl phosphine oxide (C3H9O3P) on a polyethylene (PE) matrix is proposed for high-Ni NMC batteries. A noteworthy property of the dual-purpose separator is its ability to form a thin and uniform cathode electrolyte interphase (CEI) with approximately 2 nm, primarily composed of robust LiF, on charge-discharge. As a result, the electrochemical stability is improved, demonstrating a high and stable Coulombic efficiency of ∼99.8% with a reduced impedance from ∼155.8 Ω to ∼60.3 Ω. Also, the capacity degradation decreases from 15% to 0.7% for 100 cycles (at C-rate). Another key property of the dual-purpose separator is the strong thermal stability and flame-retardant performance. During combustion test, any flames that appeared are rapidly extinguished in less than 1.0 s due to the combined flame retardant capability from the water release by heat decomposition of Mg(OH)2 and the radical (e.g. OH∙ and H∙) scavenging process by C3H9O3P. Overall, the dual-purpose separator effectively addresses the interfacial challenges and fire safety associated with high-Ni NMC batteries, concurrently, thanks to the synergetic effects between the constituents.

Hybrid artificial cathode-electrolyte interphase stimulation layer (A-CEISL) to simultaneously improve stability and safety for lithium metal batteries

In recent years, there has been significant interest in lithium metal batteries (LMBs) because of the reduced redox level and impressive specific capacity of approximately 3860 mAhg−1. Nonetheless, the high reactivity of lithium metal with combustible electrolytes poses technical barriers, including issues with unstable cycling behavior and safety challenges. In this research, a hybrid artificial cathode electrolyte interphase stimulation layer (A-CEISL) that combines an inorganic metal hydroxide (i.e., Mg(OH)2) composite with an organic dimethyl methylphosphonate (DMMP) compound is developed. The hybrid A-CEISL generates a robust and thin CEI layer (∼10 nm) during electrochemical cycling, maintaining an enhanced Coulombic efficiency as ∼99.1%. This leads to the enhanced discharge capacity on subsequent cycles. It is not only the improvement in the electrochemical properties, but also the flame-retardant and self-extinguishing features that make the hybrid A-CEISL a suitable application for LMBs. Despite multiple attempts to ignite the A-CEISL, the flame was immediately suppressed (<1 s) owing to the collaborative fire-extinguishing process between Mg(OH)2 and DMMP. Furthermore, the A-CEISL exhibits strong thermal stability, retaining its structural integrity up to 220 °C, and it still preserves its fundamental form even exposed to 300 °C. This study proposes a novel and practical approach, which benefits from the synergetic effects between Mg(OH)2 and DMMP, to concurrently tackle the primary challenges of LMBs.

Thermal stability improvement of azobenzene for the integration of photochemical and solar thermochemical energy conversion

Azobenzene is a typical photoisomerization material that is widely used in photochemical energy conversion. However, it's generally operated below 200 °C to avoid thermal decomposition. To improve the thermal stability of azobenzene for higher temperature applications, this paper discussed an option that grafting azobenzene onto graphite-like carbon nitride sheets. The synthesis was evaluated based on the performance of micro morphology and structure, thermal stability, and photochemical energy conversion. Furthermore, the photochemical conversion performance was analyzed with diverse irradiation intensities. The results demonstrate that the synthesis has a strong thermal stability below 530 °C. In this study, the most favorable excitation wavelength for photochemical conversion was 445 nm with an irradiation intensity of 40 mW/cm2.

Realization of Broadband Near-Infrared Emission with High Thermal Stability in YGa3(BO3)4: Cr3+ Borate Phosphor.

As a key material for phosphor-converted light-emitting diodes (pc-LEDs) applications, broadband near-infrared (NIR) phosphors currently face poor thermal stability issues. In this work, we synthesized a broadband near-infrared phosphor YGa3(BO3)4: Cr3+ (YGBO: Cr3+) with a high thermal stability. The YGBO: Cr3+ sample exhibits a broadband near-infrared emission centered at 770 nm with a full width at half-maximum (fwhm) of 2130 cm-1 under blue light excitation. Benefiting from the borate host crystal's strong structural rigidity, wide optical band gap, and weak electron-phonon coupling strength, YGBO: Cr3+ demonstrates strong luminescence thermal stability, and the corresponding luminescence intensity can maintain 80% at 150 °C compared to room temperature. Furthermore, we fabricated a pc-LED device using a blue light chip and YGBO: Cr3+ phosphor, and confirmed its application potential as a near-infrared light source in the spectral analysis of fruit freshness.

Complexation of V-type lotus seed starch and butyric acid: Structure and in vitro digestion

Butyric acid (BA), a short-chain fatty acid, significantly impacts gut health but is rarely incorporated as a guest molecule in starch-based products. Owing to their hydrophobic helical cavities, V-type starches can form inclusion complexes (ICs) with BA via hydrophobic interactions. In the current work, V-type lotus seed starches (VLS) were used in complexation with BA, and the structure and in vitro digestion of V-type lotus seed starch-butyric acid complexes (VLS-BAcs) as influenced by preultrasonication were investigated. The results showed that at the suitable ultrasonic power (∼360 W), 28.4% of the additional BA was complexed with preformed VLS. The IC formation significantly increased the crystallinity of starches and retarded amylose retrogradation. Highly crystallized VLS-BAcs exhibited strong thermal stability and hydrophobicity and displayed bound water-dominated structures. Moreover, VLS-BAcs formed at 360 W had a 12.4% higher RS proportion than their untreated counterparts. These obtained findings would provide valuable knowledge on the properties of VLS-BAcs modulated by ultrasound pretreatment and reveal its potential as a novel prebiotic for increasing BA concentration in the gut.

Fabrication of mesoporous SiO2/P(VDF-HFP) composite membrane for high-performance lithium-ion batteries

The aim of this work is to improve the characteristics of lithium-ion batteries (LIBs) by designing and applying advanced quasi-solid electrolytes. Mesoporous silica nanorods (m-SiO2) with a high specific surface area (537.8 m2 g−1) were prepared via a sol–gel method, then compounded with poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) and Li-salt (in organic solvent) to prepare composite gel electrolyte (m-SiO2/P(VDF-HFP)-GE) membrane. It exhibits strong thermal stability (∼353 °C), wide electrochemical stability window (5.3 V), excellent lithium-ion transfer number (tLi+ = 0.71) and high ionic conductivity (σ = 1.6 × 10−3 S cm−1). Meanwhile, when the m-SiO2/P(VDF-HFP)-GE membrane was assembled with LiFePO4 and Li, a long-cycling stable LIB with high-capacity (137 mA h g−1 at 0.3C) was obtained.

Rapid fabrication of composite membranes based on conjugated microporous polymers: Microstructural design for performance optimization

Composite membranes based on conjugated microporous polymer (CMPs) with permanent porosity and high tolerance to harsh environments have been considered as one of the most promising separation methods to treat wastewater. Nevertheless, using simple and low-cost methods to accomplish the rapid fabrication of CMPs-based membranes with excellent performance is challenging. Herein, unidirectional diffusion synthesis in diffusion cells of different inner diameters achieved the rapid fabrication and adjustable size of three CMPs-based composite membranes (i.e., TpMa-H, TpMa-CH3 and TpMa-Cl). Among them, TpMa-CH3 or TpMa-Cl was obtained by replacing -H of Carbon 4 in the amine moieties of TpMa-H with -CH3 or -Cl groups. This microstructural design enhanced the rejection rates of TpMa-CH3 and TpMa-Cl to model waste molecules compared with TpMa-H. In addition, the composite membranes had strong hydrolytic resistance, thermal stability and acid-base resistance. Interestingly, TpMa-CH3 showed better rejection to positively charged methyl violet (Mw.358) than that to negatively charged sodium cresol (Mw.404), probably due to the electrostatic adsorption of bigger positive portion of methyl violet on the membrane surface and resultant bridging effect. Such electrostatic adsorption and the adjustable microstructures significantly varied the repellence of CMPs-based membranes to different charged molecules. This work provides a beneficial idea to optimize the separation performance of the CMPs-based membrane.

Highly thermally stable single-phased white-light-emitting luminescence achieved by Dy3+ or Tb3+ Co-doped LiLa(MoO4)2:Sm3+ red-orange phosphors

A tunable white light phosphor, LiLa(MoO4)2: Sm3+, Sm3+/Dy3+, Sm3+/Tb3+, was synthesized using a high-temperature solid-state reaction method. Its luminescence properties were investigated through various analyses, including excitation and emission spectra, as well as Commission Internationale de l′Eclairage (CIE) coordinates. The results showed that Sm3+-doped LLMO exhibited a characteristic red emission at 602 nm when excited at 276 nm and retained 95.96% of its initial intensity, indicating strong thermal stability. Furthermore, by varying the co-doping concentration, the white light emission of LLMO: Sm3+/Dy3+, Sm3+/Tb3+ can be tuned, allowing for modulation of the emission color along the X and Y axes with excellent thermal stability at high temperatures, namely a high-intensity retention of 78.2% and 94.8% at 425 K, respectively. Overall, the findings suggest that the proposed phosphors hold great potential for applications in both white and colored LED lighting.

Thermally stable illuminating characteristics of Tb3+/Sm3+ ions activated BaO–SrO–Al2O3–B2O3–SiO2 glasses for photonic applications

A set of Tb3+ and Tb3+/Sm3+ co-doped barium strontium aluminium borosilicate (BaSrAlBSi) glasses were produced to examine optical properties carefully. The transparent BaSrAlBSi glass amorphous nature was established by the XRD pattern. The absorption profile demonstrates the various peaks from n-UV to NIR range caused by the Tb3+ as well Sm3+ ions in BaSrAlBSi glass. BSi:Tb1.0 glasses give intense green emission under λex = 368 nm, BSi:Sm1.0 glasses exhibit the emission spectrum caused by the transitions of the Sm3+ ions. The Tb3+/Sm3+ co-doped BaSrAlBS glasses exhibit a mixture of emission exhibited by individual ions when excited at 368 nm, whereas it exhibits only red-orange light emission when excited under 402 nm. The PL lifetimes demonstrated a reduction in decay time as Sm3+ ions concentration increased in Tb3+ doped BaSrAlBSi glasses. CIE coordinates show the green emission was tuned towards the warm white region via co-doping of Sm3+ in Tb3+ doped BaSrAlBSi glasses. The strong thermal stability of BSi:TbSm1.0 glass is confirmed via a temperature-dependent emission profile. The observed results indicate that the transparent BSi:TbSm1.0 glasses as made will be directly useful for photonic device applications as n-UV pumping results in green warm white and orange emissions.

Outstanding NLO response of K3O@thia[n]circulenes; a DFT and molecular dynamics perspective

The nonlinear optical (NLO) response of superalkali (K3O) doped thia[7&8]circulenes (1–18) is analyzed through density functional theory (DFT) calculations. The high interaction energies illustrate thermodynamic feasibility of these complexes. Natural bond orbital (NBO) charge analysis confirmed that electronic charge is transferred from K3O toward thia[7&8]circulenes. Additionally, the lowest unoccupied molecular orbital (LUMO)—the highest occupied molecular orbital (HOMO) energy gaps are reduced up to 0.81 eV after doping. Polarizability (α o) and the first hyperpolarizability (β o) values are used to estimate NLO response of doped circulenes. The highest α o and β o obtained for K3O doped thia[7&8]circulene (9) are 7297 au and 3.03 × 108 au, respectively. Two level model illustrates that the excited dipole moment as decisive factor for enhancement of NLO response. The electronic excitation is confirmed from ultraviolet-visible (UV–vis) spectroscopic analysis where all doped circulenes showed bathochromic shift. Ab initio molecular dynamics depicts strong interaction and high thermal stability of K3O doped thia[7]circulene 9. Thus, K3O doping on thia[n]circulenes (n = 7&8) remarkably enhanced the NLO response which assures the use of respective complexes in designing of building blocks for future optics.

Studies on the Nucleation, Photoluminescence, and Photoconductivity of Semi‐Organic Lithium Fumarate Crystals

AbstractSemi‐organic materials consisting of organic and inorganic semiconductors, exhibit the characteristic properties like strong optical nonlinearity and thermal stability. Lithium Fumarate (LF) is grown as a semi‐organic single crystal using lithium hydroxide and fumaric acid employing a slow evaporation method with de‐ionized water as the solvent. Classical NucleationTheory (CNT) is used to calculate the speed of LF nucleation. By altering the temperature, the thermogravimetric (TG) models, namely Coats–Redfern and Piloyan–Novikova equations are used to calculate the kinetic parameters such as enthalpy, Gibbs free energy, real heat power, and entropy of activation values. The width of the metastable zone in the LF crystal is determined by evaluating the relationship between supersaturation and temperature and it is found to exhibit a linear dependence on temperature and possess positive solubility. Lithium Fumarate's (LF) photoconductivity test shows that the grown crystal has positive photoconductivity. Photoluminescence studies conclude that Correlated Colour Temperature (CCT) values and color purity of LF crystal are suited to the green light emitting devices and flat panel displays.

Acyclic diaminocarbenes (ADCs) and their catalytic activity in metal catalysed organic transformation reactions

Abstract Acyclic diaminocarbenes (ADCs)–Metal complex having strong donor ability and thermal stability led to extensive usability across every area of inorganic and organometallic chemistry. The unique properties of acyclic diaminocarbenes (ADCs) provide certain advantages over other carbene ligands and have the potential to make a great impact in catalysis. Further, the straightforward synthesis of M–ADCs (metal bound acyclic diaminocarbenes) complexes via metal-mediated reaction provides a wide range of well-defined metal carbene catalysts, which might inspire more researchers to devise unsymmetrically substituted, chiral, and novel acyclic carbene compounds. Although the above synthetic route is limited to a few late transition metals, but have great opportunities to expand the scope of this method. The application of M–ADCs complexes as a catalyst for several organic transformation reactions such as various cross-coupling reactions and asymmetric synthesis like hydroarylation, hydroazidation, hydroamination, cyclization and addition reactions which have shown comparable or even higher activities than the analogous M–NHCs based on all the reports presented. Recent findings of donor ability of several ADC ligands would be useful in fine-tuning the electronic properties, and then a catalyst with a certain combination of donicity and steric requirement could open new doors in catalytic reactivity. Thus, the objective of this review is to assess the recent growths that have been made in designing novel and chiral ADCs ligands and synthesizing ADCs–Metal complexes and to highlight catalytic activities of metal acyclic diaminocarbene complexes for cross-coupling reactions.

Advancing novel Al-Mn-Cr-Zr based family of alloys tailored for powder bed fusion-laser beam process

Additive manufacturing coupled with modern computational tools have enabled novel alloy design possibilities to create materials for the future. One such example is the Al-Mn-Cr-Zr based family of alloys tailored for powder bed fusion-laser beam process. This alloy system has previously been shown to produce crack free samples with good precipitation hardening response and strong thermal stability up to 523 K 2500 h. The current study investigates modifications made to enhance the mechanical response of the alloys. It was done by creating three novel alloy variants with higher Zr and addition of Mg. Interestingly, increasing Zr independently triggered grain refinement while addition of Mg independently causes significant increase in as-printed hardness albeit causing solidification cracking. Desirable properties were achieved when both higher Zr and addition of Mg was done at the same time. As-printed hardness enhanced by 30 % from previously known as-printed hardness of 102 HV to 132 HV in one of the variants. Upon direct ageing, peak hardness of 172 HV is observed thus suggesting retention of precipitation hardening.

Preparation of lignin-based personal multifunctional protective mask interlayer with antibacterial, anti-UV and iodine trapping effects and exploration of its iodine trapping mechanism

Personal multifunctional protective mask is becoming an effective and convenient device for maintaining human health. When used in a normal environment, it can prevent the spread of respiratory viruses and bacteria, and absorb UV rays. When used in extreme environments full of iodine vapor, it can effectively absorb iodine vapor. Herein, an eco-friendly multifunctional nanofiber membrane with rapid sterilization ability, ultraviolet absorption and iodine vapor trapping capacity was prepared using lignin and polyvinylpyrrolidone as raw materials through electrostatic spinning technology. The results showed that PVP-WSL and PVP-IL have bactericidal rates of 21.86% and 34.08% for E. coli, 30.27% and 52.64% for S. aureus, respectively. These mask barriers have good UV resistance performance (the UV transmittance was lower than 0.015%) and effective trapping capacity of iodine vapor (the iodine maximum trapping capacity of the PVP-WSL and PVP-IL nanofiber membranes were equally determined to be 294 mg/g and 225 mg/g, respectively). In addition, these membranes have strong thermal stability (initial thermal decomposition temperature was higher than 350 °C) and mechanical properties (tensile strength higher than 1.07 MPa). This work fully meets the requirements of public health protection for degradable and high-performance media and is ideal for multifunctional personal protective equipment.

Fluorinated-cardo-based Co-polyimide membranes with enhanced selectivity for CO2 separation

The application of fluorinated polyimides in the field of gas separation membranes is becoming increasingly widespread due to their strong thermal and chemical stability. However, overcoming the separation trade-off between gas permeability and selectivity of polyimides remains a key hurdle, requiring the design of new polyimides with tailorable free volume and microstructures. Herein, we synthesized a series of polyimides containing rigid cardo groups with C-F bonds (i.e. FFDA) to increase the packing efficiency of polymer chains and thus enhance the gas selectivity of membranes. Moreover, DAM segments were copolymerized with FFDA to finely regulate the fractional free volume and produce 6FDA-FFDA/DAM copolyimide to boost gas separation performance. The CO2 permeability and CO2/CH4 selectivity of fluorinated-cardo-based copolyimide 6FDA-FFDA/DAM (1:1) are 203.4 Barrer and 43.4, respectively, performing beyond the 2008 Robeson upper bound for CO2/CH4 separation. The design principles in this work lay the groundwork for fabricating desirable polymeric membranes with tailored microstructures and properties for selective CO2 separation.

Physicochemical Characteristics of Clay Mineral from Ikpeshi in Akoko-Edo Local Government Area, Edo State, Nigeria

Clay mineral has become increasingly relevant for industrial application due to its environmentally friendly properties, low cost, and relative abundance. Several solid mineral deposits could be found in Edo State of Nigeria. This study therefore, examined the physicochemical characteristics of clay mineral from Ikpeshi in Akoko-Edo Local Government Area, Edo State, Nigeria using various standard techniques. Results obtained reveal that the sample was kaolinite with SiO2 45.116wt%, and Al2O 20.39wt% as the most predominant elements. Wavenumbers of 909.47043cm-1 to 998.92654cm-1 with bold peaks revealed the presence of SiO4-4. The study revealed that the clay from Ikpeshi has kaolinite characteristics and strong thermal stability suitable for lining furnace kilns.