Activation Energy Values Research Articles

Crystallization Kinetics and Melting Behavior of Novel Biobased Poly(butylene 2,5‐thiophenedicarboxylate)

AbstractPoly(butylene 2,5‐thiophenedicarboxylate) (PBTh) is a novel biobased semicrystalline polyester with superior thermal, mechanical, and gas barrier properties; however, the crystallization kinetics and melting behavior of PBTh have not been studied in detail so far. The crystallization kinetics of PBTh was first studied in this research. The Ozawa equation failed to describe the nonisothermal melt crystallization kinetics of PBTh due to the secondary crystallization. The crystallization activation energy value was calculated by the Friedman method, which was negative and exhibited the conversion dependence. The isothermal melt crystallization kinetics of PBTh was well described by the Avrami equation in a wide range of crystallization temperature from 84 to 120 °C. PBTh showed the fastest crystallization rate at 104 °C; moreover, the Avrami exponent value slightly varied between 2.2 and 2.7, suggesting the same crystallization mechanism within the investigated temperature range. PBTh displayed one or two melting endotherms depending on crystallization temperature, which was well explained by the melting, recrystallization, and remelting mechanism. In addition, the equilibrium melting point of PBTh was estimated to be 163.1 °C with the Hoffmann−Weeks equation.

Regulating the Electrochemical Performance of Simple Halogen-Free Electrolyte Using Ammonium Bromide Additive for Magnesium-Sulfur Battery Applications

Magnesium-sulfur (Mg-S) batteries are a promising energy storage system; however, the short cycle life, low coulombic efficiency, and the shuttle effect of polysulfide hinder its practical application. Applying electrolyte additives is a powerful technique to optimize the electrochemical performance of Mg-S electrolytes. Herein, ammonium bromide (NH4Br) is used as an inorganic electrolyte additive in the halogen-free electrolyte (HFE) to guide homogeneous Mg deposition. It can be noticed that the addition of NH4Br decreases the activation energy values from 0.14 eV to 0.10 eV and reduces the value of Mg2+ stripping/plating overpotential. It is found that the introduction of NH4Br to HFE enhances the cycle life and the initial discharge capacity (~1662 mAhg-1) of the Mg-S cells compared with the cells using free NH4Br that deliver initial discharge capacity of ~ 184 mAh g-1, low coulombic efficiency, and short cycle life. Further efforts have been devoted by implementing a BaTiO3 (BTO) as a modified separator to overcome the polysulfide dissolution issue in the cell. The surface of the cell's anode applying a modified separator shows half wt.% S content compared with the bare cell after cycling. This study opens further research for developing novel electrolyte schemes for magnesium-sulfur battery applications.

Exploring the optical and electric features of PMMA/PVAc blended polymers doped with TBAI/MWCNTs fillers for different applications

The present study focuses on the production of poly (methyl methacrylate)/poly (vinyl acetate)/tetrabutylammonium iodide/multi-walled carbon nanotubes (PMMA/PVAc/TBAI/x wt %MWCNTs) blended polymers. These blends show great potential for use in advanced optical, energy storage and electronics applications. X-ray diffraction (XRD) and scanning electron microscopy techniques was used to explore the structure and morphology of PMMA/PVAc/TBAI with x wt% MWCNTs blended polymers. The optical transmittance lowered to a minimum value of 53–63 % within the specific wavelength range as the blend contained 0.55 wt % multi-walled carbon nanotubes (MWCNTs). The sample containing 0.11 wt% MWCNTs demonstrated the highest reflectance (R) values, whereas the sample with 0.55 wt% MWCNTs showed the lowest R values. As the concentration of MWCNTs increased, these values consistently decreased. The smallest direct (4.55 eV) and indirect (4.45 eV and 2.48 eV) optical band gap (Eg) values were achieved when wt% of MWCNTs were 0.44 % and 0.55 %, respectively. The doped blend with wt% of 0.11 exhibited the highest refractive index values. Blend with x = 0.55 wt % MWCNTs has the highest dielectric constant. The energy density (U) increased non-uniformly as the blend was infused with MWCNTs. Elevating the temperature enhances the values of U for all blends. All blends adhered to the correlated barrier hopping (CBH) model. The effects of MWCNTs doping amount and temperature on the impedance and electric modulus of the host blend were investigated. The dc conductivity of the doped samples was observed to be greater than that of the undoped blend, except for the blend with x = 0.44, where it diminished. The undoped blend displayed activation energy (Ea) values of 1.71 eV and 0.6 eV, depending on the temperature range. When the host blend is doped with MWCNTs, the Ea values either rise or fall depending on the quantity of MWCNTs. All samples have non-ohmic characteristics.

Rheological Property Modification of a Molten-State Polyamide through the Addition of an α-Olefin-Maleic Anhydride Copolymer.

The rheological properties of a polyamide (PA) resin with low crystallinity were modified by melt-mixing it with a small amount of an alternative α-olefin-maleic anhydride copolymer as a reactive compound. Because PA has a low melting point, rheological characterization was performed over a wide temperature range. Owing to the reaction between PA and the alternative α-olefin-maleic anhydride copolymer, the blend sample behaved as a long-chain branched polymer in the molten state. The thermo-rheological complexity was obvious owing to large flow activation energy values in the low modulus region, i.e., the rheological time-temperature superposition principle was not applicable. The primary normal stress difference under steady shear was greatly increased in the wide shear rate range, leading to a large swell ratio at the capillary extrusion. Furthermore, strain hardening in the transient elongational viscosity, which is responsible for favorable processability, was clear. Because this is a simple modification method, it will be widely employed to modify the rheological properties of various polyamide resins.

Synergistic effect of TiO2 nanoparticles and poly (ethylene-co-vinyl acetate) on the morphology and crystallization behavior of polylactic acid

The impact of adding ethylene vinyl acetate copolymer (EVA 80) and 1 wt% TiO2 nanoparticles on the morphology and crystallization behavior of poly(lactic acid) blends was investigated using DSC, SEM, and POM. Thermal analysis revealed the enhancement of crystallinity of PLA in the presence of TiO2 and higher EVA 80 content in the blend. The PLA and EVA 80 components showed compatibility, as evidenced by the shift of the glass transition temperatures of the PLA phase in the blend to lower values compared to neat PLA. The lower temperature shift of the cold crystallization of the PLA and the formation of the small spherulites of the PLA in the blends indicated that the EVA 80 and TiO2 act as a nucleating agent for crystallization. The non-isothermal crystallization parameters of the composites were evaluated using Avrami's modified model, the MO approach, and Friedman’s isoconversional method. The Avrami’s modified rate constant (K) and the effective activation energy values significantly increased with the incorporation of EVA 80 and TiO2 nanoparticles. Furthermore, the thermogravimetric analysis (TGA) showed improved thermal stability of PLA by adding EVA 80 and TiO2.

Cobalt Nanoparticles Supported Active Carbon from Chitosan Biopolymer Using Thermal Method: Synthesis, Characterization, and Hydrogen Production

AbstractActivated carbon based Cobalt nanoparticles (Co@AC NPs), considered in the context of hydrogen energy, which is a renewable and sustainable energy, were synthesized by the hydrothermal method, and their catalytic activities were tested. For this, hydrogen production tests were carried out with the help of sodium borohydride (NaBH4) methanolysis of Co@AC NPs synthesized by the thermal method. Ultraviolet–visible spectroscopy (UV–Vis), Fourier transmission spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray diffraction (XRD) characterization tests were performed. According to the TEM characterization result, it has been observed that the NPs have a spherical shape and an average size of 2.52 ± 0.92 nm. Then, using the catalytic studies, it was observed that hydrogen production’s reusability is found to be 86% . The activation energy (Ea), enthalpy (∆H), and entropy (∆S) values were found to be 20.28 kJ⋅mol−1, 17.74 kJ⋅mol−1, and −125.97 J⋅mol−1 K−1, respectively. The obtained values have yielded excellent results and guide future sustainable and renewable hydrogen energy studies by reducing costs, ensuring environmental sustainability by avoiding the formation of undesirable by-products, and producing hydrogen from NaBH4 through its high catalytic properties.

Date nawah powder as a promising waste for β-mannanase production from a new isolate Aspergillus niger MSSFW, statistically improving production and enzymatic characterization

β-Mannanase producing fungus was isolated from coffee powder waste and identified as Aspergillus niger MSSFW (Gen Bank accession number OR668928). Dates nawah powder as industrial and agricultural waste was the most inducer of β-mannanase production. The Plackett–Burman and Central Composite designs were used to improve β-mannanase titer. Optimization studies enhanced the enzyme yield with approximate 13.50-times. β-Mannanase was purified by Sephadex G-150 gel filtration column and the molecular weight was estimated to be 60 kDa by SDS–PAGE. Crude and purified β-mannanase displayed maximum activity at temperature 60 °C and 50 °C, respectively. Crude β-mannanase showed an activation energy value 2.35-times higher than the purified enzyme. Activation energy for thermal denaturation of the purified β-mannanase was 1.08-times higher than that of the crude enzyme. Purified β-mannanase exhibited higher deactivation rate constant (Kd) and lower half-life (t0.5) and decimal reduction time (D-value) compared with the crude enzyme. Thermodynamic parameters of enthalpy, entropy, and free energy values for crude and purified β-mannanase were calculated. Substrate kinetic parameters suggested that the purified β-mannanase had a strong affinity toward locust bean gum by showing 3.44-times lower Km and 1.99-times higher Vmax compared to the crude enzyme.

Regulating the electrochemical performance of simple halogen-free electrolyte using ammonium bromide additive for magnesium-sulfur battery applications

Magnesium-sulfur (Mg-S) batteries are a promising energy storage system; however, the short cycle life, low coulombic efficiency, and the shuttle effect of polysulfide hinder its practical use. Electrolyte additives are a powerful method to optimize the electrochemical performance of Mg-S electrolytes. Ammonium bromide (NH4Br) is used as an inorganic electrolyte additive in the halogen-free electrolyte (HFE) to guide homogeneous Mg deposition. It can be observed that the addition of NH4Br decreases the activation energy values from 0.14 eV to 0.10 eV and decreases the value of Mg2+ stripping/plating overpotential. It is found that the introduction of NH4Br to HFE enhances the cycle life and the initial discharge capacity (∼1662 mAhg−1) of the Mg-S cells compared with the cells using free NH4Br that fade fast and deliver low initial discharge capacity of ∼ 184 mAh g−1. A BaTiO3 (BTO) has been utilized as a modified separator to overcome the polysulfide dissolution issue in the cell. The surface of the cell's anode applying a modified separator shows half wt% S content compared with the bare cell after cycling. This study opens further research for developing novel electrolyte schemes for magnesium-sulfur battery applications.

Effective rare-earth doping on semiconductor behavior for BaTiO3-based automotive MLCCs

Highly accelerated lifetime test (HALT) for lifetime evaluation was performed on the state-of-art automotive MLCC prototypes by varying Dy/Mg (donor/acceptor) ratio added to BaTiO3. The results clearly showed that the mean time to failure (MTTF) more than 280 times as the Dy/Mg ratio increased from 1.0 to 10.0. Since oxygen vacancies typically form in-gap state/defect at the donor level, the activation energy value under thermal activation process as a function of voltage was calculated and compared by non-destructive testing (I–V curve) for an accurate evaluation of the extrinsic behavior. It was found that barrier height at the Ni/BT interface decreases as the voltage increases, resulting in a decrease in activation energy. As the Dy/Mg ratio increases, the density of defects/in-gap states formed at the donor level in the bandgap by oxygen vacancies decreases, which may lead to a decrease in the number of electrons excited by the external voltage. Furthermore, it was verified that the calculated Schottky barrier height of the 10.0 Dy/Mg ratio under voltage has higher value than that of the 2.6 Dy/Mg ratio. Based on the results of this study, we propose a new indicator for the design of automotive MLCCs with high lifetime reliability that can be used for comparative analysis of additive compositions through non-destructive test (I–V curve) with low evaluation time/cost.

Thermal behavior analysis and biochar formation through co-pyrolysis of de-oiled microalgae biomass and wood sawdust for ecofriendly resource utilization

The co-pyrolysis of biomass wastes is of great importance for the integration of waste management and renewable energy sources, and the achievement of sustainable development goals. In this context, this study aimed to understand the reaction mechanisms and their behavior by examining the co-pyrolysis reactions of de-oiled microalgae and wood sawdust wastes. In this scope, the co-pyrolytic behavior of wood sawdust – de-oiled microalgae blends was determined by the thermogravimetric method, and co-pyrolysis kinetics and thermodynamics were calculated using model-free methods. In addition, biochar was produced from these blends under the conditions of 600 °C temperature and 20 °C min−1 heating rate, and the characterization of biochars was performed. According to the obtained results, it was observed that the degradation time of de-oiled microalgae was longer than that of wood sawdust, depending on the complexity of its structure. The main decomposition of wood sawdust occurred in a single step within the temperature range of approximately 200–400 °C, whereas the main decomposition of de-oiled microalgae occurred in multiple steps within the temperature range of approximately 200–550 °C. The calculated pyrolysis activation energy values for the biomasses ranged from approximately 149 to 180 kJ mol−1, while for the blends, these values ranged from approximately 159 to 203 kJ mol−1. Additionally, the higher HHV values of the biochars produced from the blends (approximately 10 MJ kg−1 higher than the others) increased their potential as a fuel. Based on these results, biochars produced via co-pyrolysis can be considered as a suitable option to be used as a fuel in terms of energy efficiency.

Exploration of UV-induced geometrical isomer-enriched Helichrysum kraussii extract as a corrosion inhibitor for Al(111) surface in 1.0 M hydrochloric acid: An experimental and theoretical study

This study evaluated UV-radiated Helichrysum kraussii (H. kraussii) extract for its corrosion inhibition on aluminium in 1.0 M HCl. To achieve this, techniques such as Liquid chromatography-mass spectrometry (LC-MS), Fourier transform infrared spectroscopy (FTIR), Gravimetric analysis, electrochemical analysis looking at electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP), contact angle and computational studies were used. The results obtained from these techniques made it possible to conclude the performance of UV-radiated H. kraussii as a corrosion inhibitor for aluminium metal. LC-MS and FTIR proved that the exposure of extract to UV radiation caused a change in the composition of extract metabolites, demonstrated by the increase in the number of peaks in the chromatogram and the shift in the FTIR spectrum. Weight loss technique showed that the extract inhibited the corrosion of aluminium with the maximum percentage inhibition of 84.6948 % at the concentration of 1500 ppm at 30 °C. The adsorption of the inhibitor molecules on the metal surface was found to obey the Langmuir adsorption isotherm, and the activation energy values proved that the adsorption mechanism was through physisorption. Nyquist plots semi-circles were found to increase with an increase in the extract concentration, showing an increase in the inhibition efficiency. Tafel's plot showed that both anodic and cathodic corrosion were inhibited. The DFT/PBE/GGA/DNP computational investigation obtained binding energies of the inhibitors on the aluminium surface that suggest that the Al···FA interaction happens through physical adsorption.

Shelf-life Prediction of Canned Pacri Nanas Using the Accelerated Shelf-life Test (ASLT) Method

Pacri nanas is a traditional Malay food made from fresh pineapple cooked with various herbs/spices and coconut milk. Pacri nanas can be marketed more widely if packed in cans. This study aims to estimate the shelf-life of canned pacri nanas using the Accelerated Shelf-Life Test (ASLT) method. The storage temperatures used in this study were 35 °C, 45 °C, and 55 °C. The parameters observed were sensory characteristics: color, aroma, taste, texture, and overall appearance. The results showed that all parameters decreased during storage, as indicated by the negative slope graph. The first-order reaction affects the sensory parameters decrease during storage. The lowest activation energy (Ea) value used to determine the product shelf-life is the aroma parameter with the regression equation y = -2416.4x + 5.9911, so the resulting activation energy is 4798.97 cal/mol. The shelf-life of pacri nanas at storage temperatures of 35 °C, 45 °C, and 55 °C were 11.3, 8.8, and 7.0 months, respectively. Storage of canned pacri nanas is recommended at room temperature (30 °C) with an estimated shelf-life of 12.8 months.

Novel heat exploration investigation for bioconvected Oldroyd-B nanofluid with variable thermal conductivity and Arrhenius energy induced by nailed boundary

Oldroyd-B nanofluids have potential applications in enhanced heat transfer systems, drug delivery, and advanced material processing due to their unique rheological properties. Bioconvection finds applications in biomedical research, environmental monitoring, and optimizing fluid dynamics in biotechnological and pharmaceutical processes. Due to these applications current study investigates bioconvection in the flow of Oldroyd-B nanofluid subjected to Joule heating with convected boundaries. For uniqueness of problem the effects of variable thermal connectivity and activation energy are taken into account. In addation the influence of heat source and thermal radiation are part of current model. The governing PDEs of mathematical model incorporates the Oldroyd-B rheological framework to capture the viscoelastic nature of the fluid are transformed into ODEs via similarity solution. Matlab platform via shooting algorithm is involved to solve transformed system. Through numerical simulations the stimulus of involving parameters on velocity f ′(η) temperature θ(η), concentration ϕ(η), and microbes profile X(η) are displayed in graphical and tabulated form. For strength of problem the streamlines and graphs of physical quantities are also designed. It is noted that velocity curve decreased for increasing value of magnetics parameter and opposite trend is noted in velocity distribution for increasing value of mixed convection parameter λ . Moreover, thermal layer θ is diminished for growing value of Pr , a reverse relation is noted in concentration profile for value of activation energy.

Pyrolysis-gasification conversion of waste pharmaceutical blisters: Thermo-kinetic and thermodynamic study, fuel gas analysis and machine learning modeling

It delved into the pyrolysis-gasification behavior of waste pharmaceutical blisters (WPBs), exploring both kinetics and thermodynamics, and employing machine learning modeling. The decomposition of WPBs occurred in three stages, with temperature intervals of 140–350, 350–500, and 500–900 °C, respectively. Cyclization/aromatization reactions were hindered, as indicated by mass spectrometric analysis, which revealed the main evolved products, including CxHy, CH3OH, CH4, and H2. Apparent activation energy values obtained from FWO, KAS, Friedman, Cai & Chen models were comparable, showing a decreasing trend ranging from 264.9 to 48.4 kJ mol−1 at α ≤ 0.70, followed by a subsequent increase to 283.1 kJ mol−1 at a conversion of 0.80. The D1 model was more reliable in describing the pyrolysis-gasification process of WPBs. Machine learning modeling results indicated that the ANN19 with a topology structure of 5 ∗ 15 ∗ 1 and genetic programming models showed superior performance in predicting TG data.

Physicochemical Attributes and Dynamic-Mechanical Properties of a Traditional Himalayan Cheese – Kalari

ABSTRACT Kalari is a traditionally made Himalayan cheese. It is popular in the hilly belts of Jammu and Kashmir, India, and is also known as the “Mozzarella of Kashmir.” It is prepared from raw milk by natural acidification followed by heat coagulation. The present work aims to evaluate the physicochemical and rheological characteristics of Kalari and to gain insight into its composition and functional properties. Rheological characterization based on small amplitude oscillatory shear (SAOS) measurements reveals the cheese to be a viscoelastic material, with the elastic nature dominating viscous behavior at all test conditions. Temperature sweep and Arrhenius plot also enabled to identify rheological response of Kalari at elevated temperatures, which can further elucidate its functionality. Lower values of activation energy (39.57 KJ mol−1) and phase angle (28°) reiterate that the cheese does not flow extensively but undergoes softening and slight melting on exposure to high temperatures. Physicochemical characterization revealed the cheese to possess more protein (33.8% − 42.6%) and moisture (42.9% − 48.1%) than fat (7.5% − 11.9%).

Thermokinetic study of tannery sludge using combustion and pyrolysis process through non-isothermal thermogravimetric analysis

Sludge from the tannery is produced in enormous amount. This work has investigated the thermal analysis behaviour of the tannery sludge by use of the thermogravimetric analysis (TGA). The TGA experiments is carried out in both air and nitrogen environment at the varied heating rates of 5, 10, 20 and 40 °C/min from the temperature range of 30–900 °C. In the assessment of kinetic parameters, the model fitting (Combined kinetics) method was employed. It was investigated that thermal degradation of the tannery sludge sample occurred in three stages. Majorly the conversions were observed in stage II for both in air and nitrogen environment. The activation energy (Ea) value for the combustion is 165.9 kJ/mol while for the pyrolysis the Ea value is obtained as 65.2 kJ/mol from the conversion range between 0.2 and 0.8 which is a promising approximation supported by a strong R2 value of 0.9719 and 0.93 for combustion and pyrolysis respectively. It is estimated from the master plots that six ideal models A1/2, A1/3, A1/4, F3, F4 and D5 were probably in approximation with the linear fitted data for both air and nitrogen. Various thermodynamic parameters which include the ΔH, ΔG and ΔS are also complimented that indicates the formation of activated complex and non-spontaneity of the reaction. The detailed thermokinetic study of the tannery sludge in combustion and pyrolysis offers a novel approach to understanding how this waste material decomposes under different temperature conditions. This holistic perspective contributes valuable insights into waste management practices, environmental impacts, resource recovery, and process optimization within the leather industry. Furthermore, the optimization of leather production processes on a large scale can minimize waste generation and enhance energy efficiency, strengthening the competitiveness and sustainability of the leather industry.

Beta radiation-induced thermoluminescence in pure and rare earth doped ZrO2 prepared by pechini-type sol-gel

Thermoluminescence properties of ZrO2, ZrO2:Gd3+, ZrO2:Gd3+–Dy3+, ZrO2:Gd3+–Yb3+, ZrO2:Gd3+–Er3+ and ZrO2:Gd3+–Sm3+ phosphors synthesized by Pechini method were investigated. XRD measurement suggested that all the samples are monoclinic and tetragonal multiphase. Crystallite size measured using SEM is around 200 nm–250 nm. The Tmax–TSTOP, variable dose and glow curve fitting methods were applied to the phosphors and reusability, dose responses and fading characteristics were examined. The phosphors exhibit a natural TL emission which disappeared after heat treatment. The glow curves of the pure ZrO2 have thirteen individual glow peaks, which include the peaks reported for the monoclinic and tetragonal phases. Although some peaks emerge at low irradiation doses, others can only be observed at high doses. Moreover, although the dopes blanched some of the peaks of pure ZrO2, they made others more intense. These peaks can be interpreted as if they emerged caused by the rare earth doping into the matrix material. On the other hand, Gd3+, Dy3+, Yb3+, Er3+ and Sm3+ dopes did not alter the peak temperatures of the matrix material. As a result, the individual peak intensities are very sensitive to the dopes. Fundamental trapping parameters of the trap levels were calculated, and the results are in good agreement with the given values of activation energies in the literature. Fading experiments show the materials have both normal and abnormal fading characteristics in long and short-term storage.

Desorption of humic monomers from Y zeolite: A high-temperature X-ray diffraction and thermogravimetric study

In this work, the thermal behaviour and kinetic modelling of p-hydroxybenzaldehyde (HBA) desorption was studied using both isothermal and non-isothermal methods from Y zeolite, to obtain a detailed structural and kinetic interpretation of the process. Rietveld refinement of in situ powder XRD patterns and TG analysis highlighted that the HBA thermal degradation occurred in the temperature range ∼530–750 K. This process significantly affects the geometry of the zeolite framework, thus causing a cooperative tilting of the tetrahedra and resulting in the deformation of both 6MRs and 12MRs rings. The HBA desorption experiment was also carried out in isothermal conditions at four different temperatures (473, 523, 623 and 673 K) which are selected on the basis of the relevant features from DTG/DTA curves. The value for the reaction order is nearly the same for all isothermal rates, providing strong confirmation of the validity of the reported apparent activation energy of the p-HBA decomposition process. The corresponding activation energy value (60.92 kJ/mol) agrees with literature data reported for dealuminated HZY (58 kJ/mol) and NaY.

Ultrahigh proton conductivity of four ionic hydrogen-bonded organic frameworks based on functionalized terephthalates

Recently, the utilization of hydrogen-bonded organic frameworks (HOFs) with high crystallinity and inherent well-defined H-bonding networks in the field of proton conduction has received increasing attention, but obtaining HOFs with excellent water stability and prominent proton conductivity (σ) remains challenging. Herein, by employing functionalized terephthalic acids, 2,5-dihydroxyterephthalic acid, 2-hydroxyterephthalic acid, 2-nitro terephthalic acid, and terephthalic acid, respectively, four highly water-stable ionic HOFs (iHOFs), [(C8H5O6)(Me2NH2)]∙2H2O (iHOF 1), [(C8H5O5)(Me2NH2)] (iHOF 2), [(C8H4NO6)(Me2NH2)] (iHOF 3) and [(C8H5O4)(Me2NH2)] (iHOF 4) were efficiently prepared by a straightforward synthesis approach in DMF and H2O solutions. The alternating-current (AC) impedance testing in humid conditions revealed that all four iHOFs were temperature- and humidity-dependent σ, with the greatest value reaching 10-2 S·cm−1. As expected, the high density of free carboxylic acid groups, crystallization water, and protonated [Me2NH2]+ units offer adequate protons and hydrophilic environments for effective proton transport. Furthermore, the σ values of these iHOFs with different functional groups were compared. It was discovered that it dropped in the following order under 100 °C and 98 % relative humidity (RH): σ iHOF 1 (1.72 × 10−2 S·cm−1) > σ iHOF 2 (4.03 × 10−3 S·cm−1) > σ iHOF 3 (1.46 × 10−3 S·cm−1) > σ iHOF 4 (4.86 × 10−4 S·cm−1). Finally, we investigated the causes of the above differences and the proton transport mechanism inside the framework using crystal structure data, water contact angle tests, and activation energy values. This study provides new motivation to develop highly proton-conductive materials.

A high sensitivity temperature coefficient of the Au/n-Si with (CdTe-PVA) structure based on capacitance/conductance-voltage (C/G-V) measurements in a wide range of temperature

This study focused on revealing the temperature-sensing performance and rudimental electrical-properties of the Au/(CdTe-PVA)/n-Si depending on the temperature via impedance-measurements. The temperature-sensitivity (S) for constant-capacitance drive mode shows two-distinct linear-regions corresponding to low/moderate temperatures. The highest S value was achieved as 15.5 mV/K at 0.60 nF value. Nicollian-Brews and Hill-Coleman methods were applied to determine series-resistance (RS) and density of surface-states (NSS) values. The low RS values and the proper magnitude of NSS demonstrate the high quality and performance of the Au/(CdTe-PVA)/n-Si. Additionally, the electrical parameters obtained from C-2-V plots show almost temperature-independent behavior at moderate temperature regions. The low activation-energy values (Ea) determined via Arrhenius-plot indicate hopping of the trapped electron from trap to trap or conduction band dominates the ac conduction. In conclusion, the variations of electrical-parameters and the high S value consolidate the usability of Au/(CdTe-PVA)/n-Si as a thermal sensor in the low-temperature regions.