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We propose a two-stage reduced-order model (ROM) of pharmaceutical tablet dissolution that is comprised of (i) a mechanistic dissolution function of the active pharmaceutical ingredient (API) and (ii) a tablet wetting function. The former is derived from a population balance model, using a high-resolution finite volume algorithm for a given API crystal size distribution and dissolution rate coefficient. The latter is obtained from the mechanistic understanding of water penetration inside a porous tablet, and it estimates the rate at which the API is exposed to the buffer solution for a given formulation and the dimensions of the tablet, contact angle, and surface tension between the solid and liquid phases, liquid viscosity, and mean effective capillary radius of the pore solid structure. In turn, the two-stage model is mechanistic in nature and one-way coupled by means of convolution in time to capture the start time of the API dissolution process as water uptake, swelling, and disintegration take place. The two-stage model correlates dissolution profiles with critical process parameters (CPPs), critical material attributes (CMAs), and other crucial critical quality attributes (CQAs). We demonstrate the model's versatility and effectiveness in predicting the dissolution profiles of diverse pharmaceutical formulations. Specifically, we formulate and fabricate acetaminophen and lomustine solid tablets using different API content and size distributions, characterize their dissolution behavior, and estimate capillary radius as a function of tablet porosity. The estimations generated by the proposed models consistently match the experimental data across all cases investigated in this study.
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BACKGROUND: The formation of ice crystals will have adverse effects on aquatic products, and the key to ensure the long-term preservation and better quality preservations of the product is to evaluate the intercellular ice crystal formation to find suitable refrigeration conditions and cryoprotectants. RESULTS: The ice crystal formation was successfully captured by using an inverted microscope cryomicroscopic system equipped with a low-temperature stage, the ice crystals formed under different freezing methods between tuna muscle cells were observed directly, the deformation degree of muscle tissue pores during crystallization was evaluated, and the effect of freeze-thaw times on tuna samples was analyzed. The effects of the use of cryoprotectant such as cellobiose and carboxylated cellulose nanofibers on ice-growth inhibition were investigated, and the reliability of the ice crystal observation results was further verified by the determination of physical properties. The results showed that carboxylated cellulose nanofibers had the best ice-growth inhibition effect, they prevented about 50% cell deformation compared with the control group, and also reduced the minimum size of ice crystal formation. In addition, the addition of cellobiose and sodium tripolyphosphate gave the ice crystals a more uniform size and roundness. CONCLUSION: The experiment proposed a stable and clear observation method for the process of intercellular ice crystal formation, and the accuracy of the observation method was further verified by some physical indicators. This may help in the selection of suitable measurement methods to directly observe ice crystal formation behavior and screen cryoprotectants. © 2024 Society of Chemical Industry.
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The mechanisms whereby alkali feldspar megacrysts form have been debated for several decades; yet, we do not understand well the processes that lead to their formation. We take advantage of glacially polished outcrop surfaces from the Cathedral Peak Granodiorite in the Tuolumne Intrusive Complex, CA to quantitatively characterize alkali feldspar textures, to provide better insight into their origin. On the glacially polished surfaces, we traced alkali feldspar crystals > 10 mm in the field. From the same localities, we also collected large slabs and stained them to reveal feldspar textures for crystals < 20 mm in size. We scaned the resulting field tracings and rock slabs to quantify CSDs using image processing techniques with the software ImageJ. The CSDs from glacially polished outcrop surfaces and complementary polished and stained rock slabs reveal two stages of crystallization. Crystals > 20 mm show log-linear CSDs with shallow slopes, suggesting magmatic nucleation and growth on timescales of thousands of years. Crystals < 20 mm define a second stage of crystallization, with much steeper slopes, suggesting a period of enhanced nucleation leading to formation of a groundmass during the final stages of solidification on timescales of decades to centuries. We do not find any evidence for CSDs affected by textural coarsening, or any effects of subsolidus processes. Our data suggest that these megacrysts form in large, slowly cooling magma, where low nucleation rates dominate. These crystals are not special in their magmatic formation-only in their size. A change in solidification conditions led to the formation of a groundmass, which warrants further study to better understand this crystallization stage in a plutonic environment.
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To investigate the mechanism underlying high acid resistance of enamel after erbium laser etching. Forty-five premolars were collected and assigned to three groups. A 4×4×1 mm enamel sample was prepared, the left side was the control side, the right side was the treated side, which was treated with different surface treatments, including 35% phosphoric acid etching, Er:YAG laser etching, and Er,Cr:YSGG laser etching. The hydroxyapatite crystal size on the enamel surface of the samples was observed. The contents of Ca, P, O, F, Cl, C, Mg were detected. The crystallinity of the hydroxyapatite crystal was analyzed. After erbium laser etching, the enamel surface had high hydroxyapatite crystal size, beneficial content of chemical elements and crystallinity. The morphological and composition changes of crystals in the enamel surface after erbium laser etching may be one of the crucial mechanisms underlying the enhancement of acid resistance of enamel after erbium laser etching.
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Colagem Dentária , Lasers de Estado Sólido , Érbio/farmacologia , Condicionamento Ácido do Dente , Esmalte Dentário , Hidroxiapatitas/farmacologiaRESUMO
Gated adsorption is one of the unique physical properties of flexible metal-organic frameworks with high application potential in selective adsorption and sensing of molecules. Despite recent studies that have provided some guidelines in understanding and designing structural flexibility for controlling gate opening by chemical modification of the secondary building units, currently, there is no established strategy to design a flexible MOF showing selective gated adsorption for a specific guest molecule. In a present contribution it is demonstrated for the first time, that the selectivity in the gate opening of a particular compound can be tuned, changed, and even reversed using particle size engineering DUT-8(Zn) ([Zn2(2,6-ndc)2(dabco)]n, 2,6-ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo-[2.2.2]-octane, DUT = Dresden University of Technology) experiences phase transition from open (op) to closed (cp) pore phase upon removal of solvent from the pores. Microcrystals show selective reopening in the presence of dichloromethane (DCM) over alcohols. Crystal downsizing to micron size unexpectedly reverses the gate opening selectivity, causing DUT-8(Zn) to open its nanosized pores for alcohols but suppressing the responsivity toward DCM.
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Zeolite NaY synthesized from a typical procedure could suffer from agglomeration. Adding non-refluxed cogon grass (NG) to the synthesis gel could produce NaY with good dispersion and uniform crystal size. Small molecules produced from cogon grass in alkaline conditions could prevent agglomeration. The obtained zeolite (Y-NG) has a crystallinity and surface area comparable to the synthesis without grass (Y-WG). Y-NG demonstrated similar paraquat adsorption capacity to Y-WG at high initial concentrations. On the other hand, the zeolite from the addition of acid-refluxed grass (Y-RG) has the lowest crystallinity, smallest surface area, and poorest paraquat adsorption capacity. The effect of grass amount on the zeolite structure was studied. One gram of cogon grass was the optimum amount to add to the synthesis gel.
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Ternary ceramic samples comprising SrO-MgO-SiO2 with varying element concentrations were synthesized using the solid-state method and sintered at 800°C. To characterize the properties of the samples, several analysis techniques were employed. X-ray Diffraction (XRD) was utilized for structural analysis, FTIR spectroscopy was used to identify bonds, SEM provided morphological analysis, biocompatibility was assessed through Vitro testing, microhardness was evaluated using Vickers testing, and dielectric analysis was performed to investigate electrical properties. The XRD spectra confirmed the presence of a ternary phase known as Magnesium Strontium Di-silicate [MgSr2Si2O7], with no impurity peaks detected. FTIR spectroscopy indicated the formation of Magnesium silicate, displaying vibrational bands corresponding to SiO4 and MgO, which further confirmed the existence of MgSr2Si2O7 in the samples. The Vitro test results revealed that all samples exhibited biocompatible behavior, with moderate pH and weight loss. SEM images provided insights into the morphology of the system and confirmed the development of an appetite layer on the sample surfaces. The particle size of the samples was measured to be approximately 116.48±9 nm. Vickers hardness testing yielded microhardness values ranging from 378.1 to 400.2 HV. Dielectric constant measurements demonstrated that the AC conductivity of the SrO-MgO-SiO2 system increased as the percentage of Mg doping increased.
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Óxido de Magnésio , Dióxido de Silício , Óxido de Magnésio/química , Dióxido de Silício/química , Silicatos , Dureza , MagnésioRESUMO
Accurate measurement of ice crystal size is an essential step in quantitative ice recrystallization inhibition (IRI) analysis using the sucrose sandwiching assay (SSA) and splat assay (SA). Here, we introduce a novel method of measuring ice crystal size and shape using Fiji and Cellpose, an anatomical segmentation algorithm, to address the time-consuming and limited number of ice particle determination associated with the mean largest grain size measurement. This new automated approach, displaying rapid segmentation of â¼70 s per image, measures every ice crystal in an image field of view, consequently reducing bias introduced by subjectively selecting the largest crystals in an image. Consistent in determining a diverse set of crystal sizes and shapes, this method allows for the evaluation of ice crystals using Feret's diameter, a parameter that better accounts for irregular particle shape. This method provides new outputs such as standard deviation, particle size distributions of a population of ice crystals, and circularity to characterize and further provide insight into an analyte's IRI ability. Applicable to the SSA, the "shape descriptor" measurement can be used to quantify ice binding. This work presents a novel and accurate approach for ice crystal quantitative analysis.
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Criopreservação , Gelo , Cristalização , Fiji , Criopreservação/métodos , SacaroseRESUMO
In this paper, continuous crystallization of Atorvastatin calcium (ASC) using a continuous oscillatory baffled crystallizer (COBC) has been investigated. Like most API manufacturing, ASC is manufactured batchwise and the pure API is recovered via batch combined cooling and antisolvent crystallization (CCAC) process, which has the challenges of low productivity, wide crystal size distribution (CSD) and sometimes polymorphic form contamination. To overcome the limitations of the batch crystallization, continuous crystallization of ASC was studied in a NiTech (United Kingdom) DN15 COBC, manufactured by Alconbury Weston Ltd. (AWL, United Kingdom), with the aim to improve productivity and CSD of the desired polymorph. The COBC has the advantage of high heat transfer rates and improved mixing that significantly reduces the crystallization time. It also has the advantage of spatial temperature distribution and multiple addition ports to control supersaturation and hence the crystallization process. This work uses an array of process analytical technology (PAT) tools to assess key process parameters that affect the polymorphic outcome and CSD. Two parameters were found to have significant impact on the polymorph, they are ratio of solvent to antisolvent at the point of mixing of the two streams and presence of seeds. The splitting of antisolvent into two addition ports in the COBC was found to give the desired form. The CCAC of ASC in COBC was found to be -30-fold more productive than the batch CCAC process. The cycle time for generating 100 g of desired polymorphic form of ASC also significantly reduced from 22 h in batch process to 12 min in the COBC. The crystals obtained using a CCAC process in a COBC had a narrower CSD compared to that from a batch crystallization process.
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Cristalização , Atorvastatina , Transição de Fase , Solventes/química , Reino Unido , Tamanho da PartículaRESUMO
Honey consists typically of more than 80% sugars, predominantly fructose and glucose. Glucose-rich honey crystallizes more rapidly than honey with a high fructose content. However, the size of the sugar crystals is crucial for the mouth feel of crystallised honey. Honeys containing small crystals have a creamy consistency, which is preferred by most consumers. In contrast, large crystals cause a coarse mouth feel. Factors affecting crystal size are of vital interest for the production of high-quality honey and thus analysis of sugar crystal size in honey is crucial. Here we present a simple and efficient method for measuring the size of sugar crystals in honey. A honey drop is placed on a coverslip, which is centrifuged using a converted smoothie maker. This spreads the drop over the coverslip and separates the sugar crystals from each other. Subsequently, the size of the crystals can be conveniently measured by microscopy. Compared to squeezing the honey drop between slide and coverslip, this approach avoids the risk of breaking the crystals. Moreover, the method is highly reproducible as indicated by intra-day and inter-day standard deviations of 7 to 14% for crystal sizes. Simple method for preparation of honey for crystal size analysis by microscopy. Use of cheap, easily accessible equipment. High intra and inter-day reproducibility.
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Morphology and geometrical dimensions play crucial roles in the photoelectrochemical (PEC) performance of bismuth vanadate (BiVO4) for water splitting. Decahedral BiVO4 was synthesized through a facile hydrothermal process, which exhibited superior charge injection efficiency to the nanoporous counterpart prepared by the traditional method. More importantly, the crystal size and facet proportion of BiVO4 decahedrons were facilely controlled. The charge separation efficiency can be significantly improved with a reduction in the crystal size and an increase in (040) facet exposure. A new method was developed for rate law analysis: illumination intensity-modulated oxygen evolution reaction rate versus open circuit potential difference, which suggested that the surface reaction kinetics was not affected by facet regulation. Furthermore, after decorating the FeOOH and NiOOH as dual oxygen evolution cocatalysts, an enhanced photocurrent density of 3.2 mA cm-2 at 1.23 V versus reversible hydrogen electrode and interfacial charge injection efficiency of 97.0% can be reached. Our work inspires the development of facet-regulated BiVO4 photoanodes with high charge injection efficiency in the PEC field and provides a feasible route to enhance its charge separation efficiency.
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ZSM-5 zeolites were hydrothermally synthesized with commercial silica sol, and the crystal size was controlled by adding silicalite-1 seed in the synthetic system. The crystal size of ZSM-5 was affected by the crystallization time of seed, seed content and seed size. ZSM-5 zeolites with controllable particle size in the range of 200-2200 nm could be obtained. The prepared samples with different particle sizes were used for the reaction of methanol conversion to aromatics (MTA). The results suggested that the HZSM-5 catalyst with small crystal size showed much longer catalyst lifetime and higher selectivity for C5 + hydrocarbons and aromatics, especially C9 + aromatics in the MTA reaction. Moreover, the introduction of zinc (Zn) into the HZSM-5 zeolites can considerably promote the selectivity to aromatics in the products. Zn modified HZSM-5 zeolites with different Zn loading amounts were prepared by the incipient wetness impregnation method, and the highest aromatics selectivity was obtained when the Zn loading was 1.0%. The improvement of methanol aromatization was ascribed to the synergistic effect of Brønsted acid sites and the newly formed Zn-Lewis acid sites.
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Arsenite (As(III)) and arsenate (As(V)) uptake by synthesized small- and large-sized siderites (S-siderite and l-siderite) and the effects of crystal size on arsenic sorption were investigated under extremely anoxic and neutral pH conditions. Both siderites exhibited spherical growth mechanism with an inverse relationship between crystal size and specific surface area (SSA). The maximum adsorption capacities normalized to SSA (qm,nor) of S-siderite and l-siderite were 0.161 and 0.174 mg/m2 for As(III), and 1.460 and 0.360 mg/m2 for As(V), respectively, indicating that the sorption affinity of S-siderite depends more on the arsenic species (III and V). Extended X-ray absorption fine structure (EXAFS) revealed that without oxidation change, As(V) adsorbed on both siderites forms inner-sphere complexes through bidentate-binuclear corner-sharing. In contrast, outer-sphere and inner-sphere complexes are formed for As(III) adsorbed on these siderites. In addition, the highest sorption affinity for As(V) uptake by S-siderite is attributed to the precipitation of symplesite (FeII3(AsVO4)2·8H2O), whereas the lowest sorption affinity for As(III) uptake by S-siderite was due to bicarbonates generated by the faster dissolution of S-siderite competing for sorption sites. Our findings suggest that arsenic sorption behaviors and mechanisms are strongly dependent on the arsenic species and the crystal size of siderite.
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Arsênio , Arsenitos , Adsorção , Arseniatos , Carbonatos , Compostos FérricosRESUMO
Spring blossom honey from regions with many rape fields tends to crystalize rapidly after harvesting. The crystallization process needs to be controlled by stirring in order to avoid the formation of coarse crystals and to ensure the creaminess of honey. The aim of this study was to investigate how various parameters of the stirring process influence the creaminess of spring blossom honey in order to give recommendations for beekeeping practices. The creaminess was quantified by measuring the crystal size by microscopic analysis, measuring the whiteness index by color analysis using CIE Lab and by sensory analysis. We investigated the influence of five stirring parameters, including the type of stirring device, honey pretreatment, stirring temperature (14 °C to room temperature), stirring interval (1 to 24 times) and stirring time (1-15 min) on the creaminess of honey. We found that the stirring temperature is the most important factor for honey creaminess. At the optimal temperature of 14 °C, other factors like seed honey, stirring time and stirring interval have only a neglectable effect. If the optimal temperature of 14 °C cannot be maintained, as it may happen in beekeepers' practice, sieving the honey with a mesh size of 200 µm before stirring, the addition of seed honey prepared with a kitchen food processor, and using a stirring screw and stirring several times per day is recommended.
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Controlling the crystal size and surface chemistry of MOF materials, and understanding their multifunctional effect are of great significance for the biomedical applications of MOF systems. Herein, we designed and synthesized a new anionic MOF, ZJU-64-NSN, which features 1D channels decorated with highly polarized thiadiazole groups, and its crystal size could be systematically tuned from 200 âµm to 300 ânm through a green and simple approach. As a result, the optimal nanosized ZJU-64-NSN is found to enable an ultrafast loading of cationic drug procainamide (PA) (21.2 âwt% within 1 âmin). Moreover, the undesirable chemical stability of PA@ZJU-64-NSN is greatly improved by the surface coating of polyethylene glycol (PEG) biopolymer. The final drug delivery system PEG/PA@ZJU-64-NSN is found to effectively prevent PA from premature release under the harsh stomach environments due to the intense host-guest interaction, and mainly release PA to the targeted intestinal surroundings. Such controlled drug delivery is proved to be triggered by endogenic Na+ ions instead of H+ ions, well revealed by the study on the dynamics behavior of drug release and UV-Vis absorption spectrum. Good biocompatibility of ZJU-64-NSN and PEG-coated ZJU-64-NSN has been fully demonstrated by MTT assay as well as confocal microscopy imaging.
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Herein, a simple but highly effective strategy of thermal annealing to modulate oxygen vacancies related defects in ZnFe2O4 (ZFO) nanoparticles for obtaining enhanced wastewater treatment efficiencies is reported. The as-prepared nanoparticles were thermally annealed at three different temperatures (500 °C, 600 °C and 700 °C) and their phase purity was confirmed by X-ray diffraction (XRD). All samples were found to exhibit pure phases of ZFO with different crystallite sizes ranging from 10 nm to 25 nm. The transmission electron microscope (TEM) images showed well dispersed nanoparticles and a strong correlation of grain size growth with annealing temperature was established. The optical absorption and emission characteristics were estimated through UV-visible and Photoluminescence (PL) spectroscopy. Raman spectroscopy and X-ray Photoelectron Spectroscopy (XPS) confirmed the variation of oxygen vacancies in the synthesized samples' lattice. The photocatalytic activities of all samples were investigated and the highest efficiencies were recorded for the ZFO samples annealed at 500 °C. Under high salinity condition, the organic dye degradation efficiency of the same sample remained the highest among all. The excellent dye degradation abilities in ZFO samples can be attributed to the abundance of oxygen vacancies in the crystal lattice that slow down the recombination rate during the photocatalysis process. Moreover, cytotoxicity tests revealed that all prepared ZFO samples showed insignificant cell structure effects on Picochlorum sp microalgae, as verified by Fourier-transform infrared (FTIR) spectroscopy. On the other hand, no significant changes were detected on the viable cell concentration and Chlorophyll a content. This work presents a systematic way to finely tune the crystal sizes and to modulate oxygen related defects in ZFO through a highly effective annealing approach to signify their potential in industrial wastewater and seawater treatment processes.
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Nanopartículas , Purificação da Água , Clorofila A , Oxigênio , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
The effects of the fat crystal structure on lipid droplets digestion behaviors were investigated using an in vitro digestion model. The crystalline oil-in-water emulsions containing the same solid fat content (SFC) with different fat crystal sizes and polymorphic forms were fabricated by different storage protocols: constant-temperature and inconstant-temperature storage. Oral and gastric processing led to a significant increase (p < 0.05) in the d4,3 values of the two emulsions, and the two emulsions underwent partial coalescence and flocculation/aggregation. The free fatty acid (FFA) release profiles showed that the lipolysis extent decreased due to a larger crystal size. In addition, the two emulsions showed differences in beta polymorphism. This work further demonstrated that the FFA release could be modulated by the physical properties of the fat.
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Digestão , Trato Gastrointestinal , Emulsões , Tamanho da Partícula , ÁguaRESUMO
Miniaturization is a key aspect of materials science. Owing to the increase in quality experimental and computational tools available to researchers, it has become clear that the crystal size and morphology of porous framework materials, including metal-organic frameworks and covalent organic frameworks, play a vital role in defining the physicochemical behaviour of these materials. However, given the multiscale and multidisciplinary challenges associated with establishing how crystal size and morphology affect the structure and behaviour of a material-from local to global structural modifications and from static to dynamic effects-a comprehensive mechanistic understanding of size and morphology effects is missing. Herein, we provide our perspective on the current state-of-the-art of this topic, drawn from various complementary disciplines. From a fundamental point of view, we discuss how controlling the crystal size and morphology can alter the mechanical and adsorption properties of porous framework materials and how this can impact phase stability. Special attention is also given to the quest to develop new computational tools capable of modelling these multiscale effects. From a more applied point of view, given the recent progress in this research field, we highlight the importance of crystal size and morphology control in drug delivery. Moreover, we provide an outlook on how to advance each discussed field by size and morphology control, which would open new design opportunities for functional porous framework materials.
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Soft porous crystals have the ability to undergo large structural transformations upon exposure to external stimuli while maintaining their long-range structural order, and the size of the crystal plays an important role in this flexible behavior. Computational modeling has the potential to unravel mechanistic details of these phase transitions, provided that the models are representative for experimental crystal sizes and allow for spatially disordered phenomena to occur. Here, we take a major step forward and enable simulations of metal-organic frameworks containing more than a million atoms. This is achieved by exploiting the massive parallelism of state-of-the-art GPUs using the OpenMM software package, for which we developed a new pressure control algorithm that allows for fully anisotropic unit cell fluctuations. As a proof of concept, we study the transition mechanism in MIL-53(Al) under various external pressures. In the lower pressure regime, a layer-by-layer mechanism is observed, while at higher pressures, the transition is initiated at discrete nucleation points and temporarily induces various domains in both the open and closed pore phases. The presented workflow opens the possibility to deduce transition mechanism diagrams for soft porous crystals in terms of the crystal size and the strength of the external stimulus.
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The effect of microwave radiation on the hydrothermal synthesis of the double perovskite Sr2FeMoO6 has been studied based on a comparison of the particle size and structural characteristics of products from both methods. A temperature, pressure, and pH condition screening was performed, and the most representative results of these are herein presented and discussed. Radiation of microwaves in the hydrothermal synthesis method led to a decrease in crystallite size, which is an effect from the reaction temperature. The particle size ranged from 378 to 318 nm when pH was 4.5 and pressure was kept under 40 bars. According to X-ray diffraction (XRD) results coupled with the size-strain plot method, the product obtained by both synthesis methods (with and without microwave radiation) have similar crystal purity. The Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) techniques showed that the morphology and the distribution of metal ions are uniform. The Curie temperature obtained by thermogravimetric analysis indicates that, in the presence of microwaves, the value was higher with respect to traditional synthesis from 335 K to 342.5 K. Consequently, microwave radiation enhances the diffusion and nucleation process of ionic precursors during the synthesis, which promotes a uniform heating in the reaction mixture leading to a reduction in the particle size, but keeping good crystallinity of the double perovskite. Precursor phases and the final purity of the Sr2FeMoO6 powder can be controlled via hydrothermal microwave heating on the first stages of the Sol-Gel method.