Low Thermal Treatment Research Articles

Impact of a minimally processing route for the production of infant formulas on their sensory properties

Infant formulas (IFs), the sole adequate substitute to human milk, undergo several thermal treatments during production that can damage milk proteins and promote the formation of Maillard reaction products, modifying nutritional and sensory properties. The aim of this study was to determine the impact of a minimally processing route based on membrane filtration associated with different levels of heat treatment, on the odor, taste, texture and color attributes of IFs, then to compare with those of commercial milks. Three experimental IFs (produced with membrane filtration associated with low - T-, medium - T+, or high thermal treatments - T+++) were evaluated. Triangular tests conducted with a panel of 50 adults highlighted clear disparities between all the IFs. The same panel applied the Check-All-That-Apply method to evaluate the IFs: the range of variability between T- and T+++ was similar to that between the 2 commercial IFs, and the sensory characteristics of the experimental IFs were not far from the commercial brands for flavor and texture attributes. Analysis performed on the citation frequencies for each descriptor differentiated T-/T+ from T+++, but all the experimental IFs were described with positive sensory characteristics, unlike one commercial IF. Volatile organic compounds (VOCs) content of IFs with low and high thermal treatments were analyzed. Forty VOCs were identified by gas chromatography-mass spectrometry. T- contained a higher quantity of VOCs than T+++, except for benzaldehyde (Maillard reaction product), and aldehydes (oxidation-related products) were the most represented compounds. In conclusion, the processing was associated with sensory differences among IFs, but no marked difference in flavors was found according to CATA and physicochemical analysis. Additionally, no unpleasant sensory descriptors were noted. This shows that the minimally processed route leads to IFs that could fit well within the market from a sensory point of view.

Physiological thermal responses of three Mexican snakes with distinct lifestyles.

The impact of temperature on reptile physiology has been examined through two main parameters: locomotor performance and metabolic rates. Among reptiles, different species may respond to environmental temperatures in distinct ways, depending on their thermal sensitivity. Such variation can be linked to the ecological lifestyle of the species and needs to be taken into consideration when assessing the thermal influence on physiology. This is particularly relevant for snakes, which are a very functionally diverse group. In this study, our aim was to analyze the thermal sensitivity of locomotor performance and resting metabolic rate (RMR) in three snake species from central Mexico (Crotalus polystictus, Conopsis lineata, and Thamnophis melanogaster), highlighting how it is influenced by their distinctive behavioral and ecological traits. We tested both physiological parameters in five thermal treatments: 15 °C, 25 °C, 30 °C, 33 °C, and 36 °C. Using the performance data, we developed thermal performance curves (TPCs) for each species and analyzed the RMR data using generalized linear mixed models. The optimal temperature for locomotion of C. polystictus falls near its critical thermal maximum, suggesting that it can maintain performance at high temperatures but with a narrow thermal safety margin. T. melanogaster exhibited the fastest swimming speeds and the highest mass-adjusted RMR. This aligns with our expectations since it is an active forager, a high energy demand mode. The three species have a wide performance breadth, which suggests that they are thermal generalists that can maintain performance over a wide interval of temperatures. This can be beneficial to C. lineata in its cold habitat, since such a characteristic has been found to allow some species to maintain adequate performance levels in suboptimal temperatures. RMR increased along with temperature, but the proportional surge was not uniform since thermal sensitivity measured through Q10 increased at the low and high thermal treatments. High Q10 at low temperatures could be an adaptation to maintain favorable performance in suboptimal temperatures, whereas high Q10 at high temperatures could facilitate physiological responses to heat stress. Overall, our results show different physiological adaptations of the three species to the environments they inhabit. Their different activity patterns and foraging habits are closely linked to these adaptations. Further studies of other populations with different climatic conditions would provide valuable information to complement our current understanding of the effect of environmental properties on snake physiology.

Elucidating influences of defects and thermal treatments on CO2 capture of a Zr-based metal–organic framework

Carbon capture and storage (CCS) technology is currently an essential response to the global warming problem caused by excessive CO2 emissions. Efficient and reproducible adsorbents for flue gas treatment play an important role in CCS technology, and metal–organic frameworks (MOFs) are considered to be ideal candidates by virtue of their designable CO2 sorption sites. However, carbon capture performance evaluation and reproducibility of MOFs still hinder their application promotion in industrial production. In this work, an extended UiO-66-type MOF based on 1,4-naphthalenedicarboxylate, was successfully synthesized in both a near defect-free form (UiO-66N) and a defect-rich form (DUiO-66N), for exploring the influence of crystalline defects and thermal treatments on carbon capture performance. Although powder X-ray diffraction showed that UiO-66N and DUiO-66N possessed the same crystalline phase, transmission electron microscopy, thermalgravimetric analyse and gas/dye sorption confirmed the presence of crystalline defects and the variation of porosity in DUiO-66N. CO2 sorption isotherms and flue gas breakthrough experiments revealed the defect-induced improved carbon capture performance, which was also supported by density functional theory. Meanwhile, the metastability of defects required low thermal treatment temperatures for activation and regeneration thus maintaining the superior carbon capture performance. These findings suggested that in reproducing and evaluating the carbon capture performance of MOFs, it cannot rely only on the global crystalline phase judgment, but needs to identify the local fine structure as well as optimize activation and regeneration conditions.

3D conductive monolithic carbons from pyrolyzed bamboo for microfluidic self-heating system

Bamboo, like wood, is a promising natural template for biobased devices that takes advantage of its hierarchical architecture, microarray channels, anisotropic mechanical and electrical properties. Herein we report a low heat thermal treatment (HTT, 700-1000 °C) of natural bamboo specimens to obtain bamboo-based graphitic devices with thermoelectric and electrochemical properties. The preservation of the highly anisotropic architecture of three-dimensional carbon material (3D-CM) allowed adding specific thermoelectric and electrochemical properties depending on the HTT of the pristine specimens. High electric conductivity (σ, 839 S/m) was observed at 1000 °C showing a remarkable potential application as a bamboo-based working electrode. The bamboo annealed to 700 °C showed higher resistivity (ρ, 0.15 Ω m, and σ, 6.6 S/m), thermal conductivity (1.77 W/m K), and thermal heating rate (1.0 °C/s). The pyrolyzed biomass (B-700) was used as a 3D microfluidic heater to heat polar solvents (H2O and ethylene glycol) in flow mode up to their boiling points. A 2D carbon hotplate heater was built-up to warm solvent in batch mode. A complete chemical and physical characterization of the samples allowed us to determine structural and chemical compositions, cellulose crystalline structure phase transition to graphitic/turbostratic carbon, thermal and electrical conductivity of unprecedented bambootronics bio-devices.

Life Cycle Analysis of a Green Solvothermal Synthesis of LFP Nanoplates for Enhanced LIBs in Chile.

Despite the structural and electrochemical advantages of LiFePO4 (LFP) as a cathode material, the solid-state reaction commonly used as a method to produce it at the industrial level has known disadvantages associated with high energy and fossil fuel consumption. On the other hand, solution-based synthesis methods present a more efficient way to produce LFP and have advantages such as controlled crystal growth, homogeneous morphology, and better control of pollutant emissions because the reaction occurs within a closed system. From an environmental point of view, different impacts associated with each synthesis method have not been studied extensively. The use of less polluting precursors during synthesis, as well as efficient use of energy and water, can provide new insights into the advantages of each cathode material for more environmentally friendly batteries. In this work, a solvothermal method is compared to a solid-state synthesis method commonly used to elaborate LFPs at the commercial level in order to evaluate differences in the environmental impacts of both processes. The solvothermal method used was developed considering the reutilization of solvent, water reflux, and a low thermal treatment to reduce pollutant emissions. As a result, a single high crystallinity olivine phase LFP was successfully synthesized. The use of ethylene glycol (EG) as a reaction medium enabled the formation of crystalline LFP at a low temperature (600 °C) with a nano-plate-like shape. The developed synthesis method was evaluated using life cycle analysis (LCA) to compare its environmental impact against the conventional production method. LCA demonstrated that the alternative green synthesis process represents 60% and 45% of the Resource Depletion impact category (water and fossil fuels, respectively) of the conventional method. At the same time, in the Climate change and Particular matter impact categories, the values correspond to 49 and 38% of the conventional method, respectively.

Optimization of low thermal treatments to increase hydrophilic phenols in the Alperujo liquid fraction

Hydrophilic phenols are the main bioactive compounds in alperujo. Among them, 3,4-Dihydroxyphenylglycol (DHPG), Hydroxytyrosol (HT) and Tyrosol (Ty), are the most relevant and deeply studied. These compounds exhibit high antioxidant capacity and a wide range of health benefits as well as technologically promising properties. Given that, their recovery represents an attractive opportunity to valorize this by-product. In this work low thermal treatments were applied to alperujo in order to obtain phenol-enriched liquid fractions. Optimization assays combining different levels of temperature (30 to 90 ºC), time (60 to 180 min) and water content (70 to 90%), followed by response surface methodologies were performed. The results indicated that by applying optimal conditions, is possible to obtain theoretical yields of Total phenols, DHPG, HT and Ty of 2.4, 957.8, 3.4 and 6.4 times greater, respectively, than raw dry alperujo. Interestingly, all the evaluated conditions can be reproduced with low investment in a standard olive oil industry.

Spinel structure of activated carbon supported MFe2O4 composites as an economic and efficient electrocatalyst for oxygen reduction reaction in neutral media

For more sustainability and marketing of microbial fuel cells (MFCs) in wastewater treatment, the sluggish kinetics of cathode oxygen reduction reaction (ORR) and platinum scarcity (with its high cost) should be swept away. So, this work aimed to synthesize metal ferrite (MFe2O4; M = Mn, Cu, and Ni) -based activated carbon composites as inexpensive ORR cathode catalysts. The composites were synthesized using a facile modified co-precipitation approach with low-thermal treatment and labeled as MnFe2O4/AC, CuFe2O4/AC, and NiFe2O4/AC. The as-synthesized catalysts are physicochemically characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared microscopy (FTIR), Barrett-Joyner-Halenda (BJH), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and electron spin resonance (ESR). The electrochemical catalytic performance toward ORR was studied in a phosphate buffer solution (PBS) at neutral media via cyclic voltammetry (CV) and linear sweep voltammetry (LSV). MnFe2O4/AC has the highest onset potential (Eonset) value of − 0.223 V compared to CuFe2O4/AC (− 0.280 V) and NiFe2O4/AC (− 0.270 V). MnFe2O4/AC also has the highest kinetic current density (jK) and lowest Tafel slope (− 5 mA cm−2 and − 330 mV dec−1) compared to CuFe2O4/AC (− 3.05 mA cm−2 and − 577 mV dec−1) and NiFe2O4/AC (− 2.67 mA cm−2 and − 414 mV dec−1). The ORR catalyzed by MnFe2O4/AC at pH = 7 proceeds via a 4e− -kinetic pathway. The ESR is in good agreement with the electrochemical analysis due to the highest ∆Hppvalue for MnFe2O4/AC compared to CuFe2O4/AC and NiFe2O4/AC. Thus, MnFe2O4/AC is suggested as a promising alternative to Pt- electrocatalyst cathode for MFCs at neutral conditions.Graphical

Development of a predictive model of the microbial inactivation of L. monocytogenes during low thermal treatment of fruit juices in combination with carvacrol as aroma compound

Mild heat treatment of fruit juices in combination with natural aroma compounds has been reported as an alternative to conventional pasteurization to better preserve their nutritional value. However, its antimicrobial efficiency varies from one juice to another. This study aims at developing a secondary predictive model of microbial inactivation scale during such combined process. Carvacrol was used as aroma compound and acid-adapted L. monocytogenes as target microorganism. The inactivation kinetics of this bacteria were followed in simulated fruit juices using a Central Composite Design with pH (2-6), °Brix (0–24), temperature (55–65 °C), and carvacrol concentration (0–60 μL/L) as independent variables. Curves were fitted to the Weibull inactivation model, and data collected used to generate two predictive models of the inactivation scale parameter through multiple regression analysis following an empirical and a mechanistic (based on Gamma concept) approach. The best of the two models was then validated using real fruit (orange, pineapple, and watermelon) juices. The empirical model where only the four variables tested were considered showed a lower statistical performance compared to the mechanistic model where octanol-water partition coefficient (Ko/w) and vapour pressure (Vp) of carvacrol at the treatment temperature were integrated (R2 0.6 and 0.9; Accuracy factor 1.5 and 1.3; Sum of Squared Error 3.6 and 1.1, respectively). No significant difference was observed between inactivation scale values obtained with real juices and the predicted values calculated using this mechanistic model. The Ko/w and Vp of the aroma compound used are key parameters that determine the efficiency of the above-described combined treatment.

Improving the Ionic Conductivity of the LLZO–LZO Thin Film through Indium Doping

A solid-state electrolyte with an ionic conductivity comparable to that of a liquid electrolyte is demanded of all-solid-state lithium-ion batteries. Li7La3Zr2O12 (LLZO) is considered to be a promising candidate due to its good thermal stability, high ionic conductivity, and wide electrochemical window. However, the synthesis of a stable cubic-phase LLZO thin film with enhanced densification at a relatively low thermal treatment temperature is yet to be developed. Indium is predicted to be a possible dopant to stabilize the cubic-phase LLZO (c-LLZO). Herein, via a nanolayer stacking process, a LLZO–Li2CO3–In2O3 multilayer solid electrolyte precursor was obtained. After thermal annealing at different temperatures, the effects of indium doping on the formation of c-LLZO and the ionic conductivities of the prepared LLZO–LZO thin film were systematically investigated. The highest ionic conductivity of 9.6 × 10−6 S·cm–1 was obtained at an annealing temperature of 800 °C because the incorporation of indium promoted the formation of c-LLZO and the highly conductive LLZO–LZO interfaces. At the end, a model of LLZO–LZO interface-enhancing ionic conductivity was proposed. This work provides a new approach for the development of low-temperature LLZO-based, solid-state thin-film batteries.

Genetic pathways underpinning hormonal stress responses in fish exposed to short- and long-term warm ocean temperatures

Changes in ocean water temperature associated with global climate change are bound to enormously affect fish populations, with potential major economic consequences in the aquaculture and fisheries industries. A link between temperature fluctuations and changes in fish stress response is well established. In this study, we aimed to assess the effects of a short- (4 days) or a long-term (4 months) exposure to warm temperature in the stress physiology of European sea bass (Dicentrarchus labrax) larvae and juveniles. First, cortisol (i.e. the main stress hormone in fishes) analysis was used to confirm that a steady and short-term elevation of temperature acts as a physiological stressful event in these fish, and cortisol release is indeed above a metabolic increase linked to temperature. Moreover, our results verified that measurement of cortisol released into the water can be reliably employed as a non-invasive indicator of acute thermal stress in experimental conditions. Secondly, the different effects on the genetic cascade underlying the stress response between long-term low or high thermal treatments were evaluated at two larval development stages via candidate-gene and whole-transcriptome approaches. Interestingly, opposite expression for some key stress genes (nr3c1, nr3c2 and hsd11b2) were observed between developmental stages, highlighting the distinct adaptive mechanisms controlling the primary and secondary responses to a stressor. Surprising expression patterns for some understudied genes involved in the stress axis were also revealed, including crhr1, mc2r, mc5r, trh or trhr, which should be further explored. Finally, evaluation of cortisol content in scales was successfully used as a biomarker of chronic thermal stress, with 10x more cortisol in fish kept at 21 °C vs 16 °C after 4 months, supporting the gene expression results observed. The use of such a method as a proxy of long-term stress, unprecedented in the literature, holds a vast array of applications in further research, in particular, in the investigation of the impact of global warming on wild fish populations.

Effect of Simplified-Single-Step Microwave Annealing in O2 Ambient for High Performance Solution-Processed In–Ga–Zn–O Thin Film Transistors

In this study, we propose a simplified-single-step microwave annealing (S₃-MWA) technique in an O₂ ambient, which is a low thermal budget heat treatment method, for the application in solutionprocessed amorphous indium-gallium-zinc oxide (a-IGZO) thin films. For the application of solutionprocessed a-IGZO films in electronic devices, a multi-step post deposition annealing (PDA) process, which involves baking at low temperatures to vaporize the solvent, and high temperature conventional thermal annealing to remove defects in the film, is essential. To simplify the multi-step PDA process, we studied the possibility of reducing the thermal process temperature and time by replacing it with a single-step PDA process using microwave equipment. The electrical properties were compared to investigate the effect of the annealing method and ambient on solution-processed a-IGZO thin film transistors (TFTs). As a result, the S₃-MWA-processed a-IGZO TFTs were found to exhibit superior electrical characteristics in comparison with the conventional PDA-processed devices. It was found that the O₂ ambient process not only shortened the annealing time of S₃-MWA but also improved the electrical properties. Furthermore, the S₃-MWA was superior to the conventional PDA in the evaluation of device reliability under a gate bias stress test. The S₃-MWA process in the O₂ ambient was also responsible for improving the reliability of solution-processed a-IGZO TFTs. Therefore, we confirmed that the proposed S₃-MWA in the O₂ ambient is a more effective and promising technique than conventional PDA for the low thermal budget treatment of solution-processed a-IGZO TFTs.

Synthesis and Characterization of White Mineral Trioxide Aggregate Using Precipitated Calcium Carbonate Extracted from Limestone

White Mineral Trioxide Aggregate (WMTA) using precipitated CaCO3 (PCC) from limestone has been synthesized. PCC in calcite structure was extracted from limestone by calcination at 900 °C for 3 h, dissolved in 0.8 M nitric acid solution and followed with carbonation for 60 minutes. PCC was used for the synthesis of WMTA by mixing with tetraethoxyorthosilicate, bismuth oxide, aluminum oxide, catalyst of with HNO3 and NH3 solution and thermally treated at 1100 °C for 3 h. The products were characterized with Thermal Gravimetric Analysis-Differential Thermal Analysis (TGA-DTG), X-ray Diffraction (XRD), Frontier-Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and X-ray Fluorescence (XRF). The results showed that the PCC dominated calcite structure was obtained with 75.25% in yield and 99.42% in purity. The WMTA has been successfully synthesized by low thermal treatment at 1100 °C using catalysts of HNO3 and NH3 solution, proven by the presence of tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and Bi2O3 in WMTA.

In situ microwave-assisted deposition of CoS counter electrode for dye-sensitized solar cells

High electrocatalytic activity and conductivity are two unshakable objectives for the counter electrode used in dye-sensitized solar cells (DSSCs). Cobalt sulfide (CoS) has been deposited on the fluorine-doped tin oxide (FTO) substrate using the microwave-assisted chemical bath with very low thermal treatment, in the range of 100–120 °C. This deposition method improves the electrocatalytic properties of Pt-free materials and offers to reduce numerous film-making steps by direct synthesis-deposition onto the FTO. The counter electrodes were evaluated in symmetrical dummy cells and tested in solar cells. Results achieved with low-temperature exhibit a power conversion efficiency of 8.39% against 7.88% of the commercial Pt, which demonstrates that it can be used as a Pt-free counter electrode for high-performance DSSCs.

Performance Recovery in Degraded Carbon-Based Electrodes for Capacitive Deionization.

Limitations of capacitive deionization (CDI) and future commercialization efforts are intrinsically bound to electrode stability. In this work, thermal treatments are explored to understand their ability to regenerate aged CDI electrodes. We demonstrate that a relatively low thermal treatment temperature of ∼500 °C can sufficiently recover the lost salt adsorption capacity of degraded electrodes. Furthermore, a systematic study of electrode replacement clarifies that the desalination ability loss and regeneration for a CDI cell are isolated to the aged anode, as expected. Characterizations of surface functionalities support that the acidic oxygen-containing functional groups formed in situ during cycling undergo thermal decomposition during treatment. The modified Donnan model quantitatively confirms that the surface charges originate from the formation/decomposition of functional groups. Accordingly, the lost pore volume and the increased resistance are recovered during thermal treatments, while the surface morphologies and pore structure of the electrodes are well-preserved. Therefore, thermal treatment can be applied practically to extend the lifetime of aged electrodes. This study also offers insights into strategies for minimizing electrode degradation or in situ regeneration such that the technology gains momentum for future commercialization.

Fabrication of exfoliated graphitic carbon nitride, (g-C3N4) thin film by methanolic dispersion

This paper reports the successful exfoliation of nanosheets from bulk g-C3N4 by using urea as a precursor. The alteration from bulk g-C3N4 powder, changed its semiconductor arrangements such as the optical absorption, chemical bonding, and topography images. A slow direct low thermal treatment (∼40 °C, 24 h) was proposed as a formation of a thinner layer by layer, complete and effective polymerization for an exfoliated g-C3N4. The photocurrent responses were more than two times higher for exfoliated g-C3N4 compared with bulk g-C3N4, reaching ∼4.37 μA cm−2 up to 10.21 μA cm−2 at 1.23 vs. (Ag/AgCl). This fabrication method involved dispersing of the highly stable g-C3N4 suspension onto FTO surface via spin coating, followed by a moderate post-annealing temperature at 350 °C. The monolayer g-C3N4 act as a photoelectrode, responding to light and dark current, and maintained its own intrinsic n-types properties. The interaction of the C and N atom with molecules of methanol (CH3OH) followed with vibration force (ultrasonication) produces the ultrafast drying and can transmit to disrupt the van der Waals forces within the g-C3N4 structure. Therefore, due to the ability the good performance, the exfoliated g-C3N4 can be envisioned as a potential application such as water splitting, solar cell, and environmental remediation.

Effect of low thermal treatment temperatures on the morphological, optical and electrical properties of Sn1-xMnxTe nanocomposite films incorporated with indium cations

Amorphous chalcogenide semiconductors have advantageous optical and electrochemical properties, but the influence of the thermal treatment temperature on these properties is not clearly understood. In this study, In3+-incorporated Sn1-xMnxTe nanocomposite films were prepared on commercial glass substrates using a solution-based doctor-blading method and low thermal treatment temperatures. The effect of the thermal treatment temperature (50–200 °C) on the optical and electrical properties of the nanocomposite films was investigated. X-ray diffraction results confirmed that an amorphous nanocomposite film was formed at each thermal treatment temperature. However, variation in the optical parameters and electrical performance of the nanocomposite films with the thermal treatment temperature indicated that this temperature should not exceed 150 °C. Optimization of the thermal treatment temperature improved the light-harvesting ability of the nanocomposite films and enhanced the polarization of the incident radiation. These phenomena were caused by an increase in atomic oscillations associated with higher dipole moments in the films. The nanocomposite films subjected to thermal treatment at temperatures below 150 °C also exhibited the highest electrical conductivity. These results will allow the synthesis of improved materials for applications in solar selective surfaces and electro-optical, photovoltaic-thermal, and sensor devices.

X-Ray Diffraction Evaluation of the Average Number of Layers in Thermal Reduced Graphene Powder for Supercapacitor Nanomaterial

Graphene oxide (GO) can be partially reduced to graphene-like sheets by removing the oxygen-containing groups and recovering the conjugated structure. In this work, the thermal reduction of GO powder has been carried out using back pumping vacuum pressures and investigated employing X-ray diffraction analysis. The experimental results of estimating the number of graphene layers on the reduced powder at various temperatures (200 – 1000 °C) have been reported. Electrical changes have been produced in a graphene oxide with the vacuum reduction process. This study has shown that the ideal processing temperature for reducing graphene oxide nanomaterial was about 400 °C. It has also been shown that at 600 °C the number of layers in the reduced nanomaterial increased. The internal series equivalent resistance (ESR) has been improved substantially with the vacuum thermal treatment even at temperatures above 400 °C. ESR was reduced from 95.0 to about 13.8 Ω cm2 with this processing. These results showed that the process can be applied to the reduction of graphene oxide to produce supercapacitor nanomaterials. The advantage of employing this method is that the processing is a straightforward and low cost thermal treatment that might be used for large amount of nanocomposite material.

The study of the effect of external additives on the synthesis of fumed TiO2 with a high content of rutile structure by the novel natural dropping thermal treatment

The effect of external additives on the synthesis of fumed TiO2 with a high rutile structure content was studied. The focus of this investigation was on the external additive species, agglomerates of the fumed TiO2 before and after the thermal treatment. The transformation ratio from the anatase to rutile structure of the thermally-treated fumed TiO2 was investigated as a function of the fumed TiO2 agglomerate before the thermal treatment. Small agglomerated powders resulted in a decrease of transformation temperature. Two novel results were obtained in this investigation. One was a new fumed TiO2 with a 100% rutile structure having an excellent dispersibility being successfully synthesized by the thermal treatment of AEROXIDE® TiO2 P 25 with a small portion of AEROSIL® R 972. The other was the remarkable acceleration of the transformation from the anatase to rutile structure and grain growth/sintering of the thermally-treated fumed TiO2 observed at a relatively low thermal treatment temperature by the oxidation reaction of calcium stearate as an external additive.

Effect of Chemical Composition and Crystal Phase of (Li,Na)FeO2 Ferrites on CO2 Capture Properties at High Temperatures

In this work, we present the synthesis of lithium- and sodium-based ferrites by nitrate decomposition, using low and short thermal treatments. X-ray diffraction and Rietveld refinement were used to...

Magnetic properties of cobalt doped ZrO2 nanoparticles: Evidence of Co segregation

We synthesized pure and Co-doped (6.25%–12.5% at.) ZrO2 nanopowders in order to study their magnetic properties. We analyzed magnetic behavior as a function of the amount of Co and the oxygenation, which was controlled by low pressure thermal treatments. As prepared pure and Co-doped samples are diamagnetic and paramagnetic respectively. Ferromagnetism can be induced by performing low pressure thermal treatments, which becomes stronger as the dwell time of the thermal treatment is increased. This behavior can be reversed, recovering the initial diamagnetic or paramagnetic behavior, by performing reoxidizing thermal treatments. Also, a cumulative increase can be observed in the saturation of the magnetization with the number of low pressure thermal treatments performed. We believe that this phenomenon indicates that cobalt segregation induced by the thermal treatments is the responsible for the magnetic properties of the ZrO2-Co system.