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... well-known examples of these samples are glycerin and glycine complexes of transition metals, in particular copper. Table 1 gives data for comparing the strength of glycine and other transition metal complexes. The possibility to form associates between similar metal ions and polymer components expands the homogeneity area on the phase diagrams, as well as inhibits secretion and growth of phase non-homogeneities Fig. 1) along the A-B line. ...
Citations
... Mercury and copper are heavy metals known for their toxicity even at low concentrations, and they are usually found in water matrices [45,46]. In addition, these heavy metals can form complexes with organic ligands present in the water that can interfere in the analysis of the studied molecules [47][48][49][50]. Methomyl is a carbamate pesticide, and depending on its concentration, it can be mortal to mammals [51]. ...
This research describes the modification of a glassy carbon electrode with spent coffee grounds hydrochar (HDC) and copper nanoparticles (CuNPs) for the simultaneous determination of hydroxychloroquine sulfate (HCS) and bisphenol A (BPA). Scanning electron microscopy, EDS and cyclic voltammetry were used to characterize the nanocomposite. The analytical parameters were optimized and the sensing platform was applied for the determination of HCS and BPA using square-wave voltammetry (SWV). For HCS, the linear range was from 1.0 μmol L−1 to 50 μmol L−1, with an LOD and LOQ of 0.46 and 1.53 μmol L−1, respectively. For BPA, the linear range was from 0.5 μmol L−1 to 10 μmol L−1, with an LOD and LOQ of 0.31 μmol L−1 and 1.06 μmol L−1, respectively. Finally, the developed electrochemical sensor was applied for the quantification of the emerging contaminants in natural water, with recoveries between 94.8% and 106.8% for HCS and 99.6% and 105.2% for BPA. Therefore, HDC-CuNPs demonstrated themselves to be a good alternative as a sustainable and cheaper material for application in electroanalyses.
... The properties of complex oxide materials obtained via combustion reactions are influenced by such conditions as process temperature, composition and concentration of the gases formed. One of the important phenomena accompanying the synthesis processes of complex oxides by combustion of nitrate-organic precursors [5,16,19, is the generation of high-density electric charges in the precursors and nanoparticles [45,[56][57][58][59][60][61][62][63]. The possibility of charge formation is associated with the release of ionized molecular groups into the gaseous environment and also with the lability of the oxidation state of transition metal ions which are the part of the precursors and the resulting material. ...
... Solutions of polymer components (concentration of PVA or PVP -5 or 10 wt.%, respectively) were prepared by heating in a water bath. When mixing the two solutions, the quantitative proportions were set in accordance with the stoichiometry of the nitrate combustion reaction with the formation of nitrogen, carbon dioxide and water as gaseous products [56]. The resulting solution was poured onto inert substrates, further evaporation of water (drying) took place at room temperature, this process took up to 7 days, as a result of which precursors in the form of films containing a stoichiometric amount of an organic component (ϕ = 1) or its double excess (ϕ = 2) were obtained. ...
... A significant disadvantage of the method of chemical precipitation of metal hydroxides is a high degree of agglomeration of the synthesized powders and their wide grain-size distribution [14]. In order to increase the dispersion of the final powders (by reducing the coagulation of deposited particles and preventing agglomerate formation), the technique of solution combustion synthesis has been developed in recent years [15][16][17][18][19][20][21][22][23][24][25][26]. The process involves an exothermic reaction between an oxidizing agent such as metal nitrates and a fuel such as urea (H2NCONH2), carbohydrazide (CO(NHNH2)2), or glycine (C2H5NO2). ...
We investigated the feasibility of synthesizing nanopowders containing indium and dysprosium oxides by the glycine-nitrate method. It was found that the glycine-nitrate method significantly reduces the content of the indium component in the resulting mixture of indium and dysprosium oxides. In this case, intensive absorption of carbon dioxide from the air by the formed particles induces formation of amorphous carbonaceous compounds, which decompose only under high-temperature treatment (900 °C). This prevents compaction of powders synthesized by the glycine-nitrate method. Comparison of the characteristics of powders containing indium oxides and dysprosium, synthesized by the glycine-nitrate method and by the method of co-precipitation of indium and dysprosium hydroxides from chloride solutions, showed the advantage of the co-precipitation method in the pressing of powders.
... One of the promising methods of synthesis of complex oxides is the method of glycine-nitrate combustion [50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65]. At the same time, this method not always guarantees the possibility of one-stage synthesis of complex oxide phases [22,28,32,33,46,58]. ...
... Важным моментом в плане формирования целевых характеристик таких материалов является метод и условия синтеза, что в особенности относится к наноструктурированным объектам. К широко используемым способам получения перовскитов и других сложнооксидных материалов относятся методы, основанные на процессах горения органонеорганических прекурсоров [2,3,[9][10][11][12][13], где в качестве солевых форм обычно используются нитраты соответствующих металлов. ...
... -Вып. 14 В реакциях горения нами обнаружен эффект генерирования в прекурсорах электрических зарядов высокой плотности [10,11,14,15] положительного или отрицательного знака. Явление связано с выходом в газовую среду ионизированных молекулярных группировок. ...
Lanthanum manganite doped with strontium samples were synthesized by the combustion method of nitrate-organic precursors of different composition. The combustion process was realized under the influence of an external alternating electromagnetic field and in its absence. It was found that thermochemical generation of charges occurs during precursor’s combustion, recorded as a potential difference of precursor-earth. It is shown that the composition of the initial precursor (organic component and its quantity), as well as the presence of an external alternating electromagnetic field, affect the magnitude of the potential difference that occurs, varying from -7 to 125 V. The relationship between the studied electromagnetic properties (saturation magnetization, coercive force, Curie temperature) of the obtained samples and the precursor–earth potential difference arising during synthesis is shown. The Curie temperature values varied in the range of 38-79°C for samples obtained under the influence of an alternating electro-magnetic field, and 49-104°C in its absence.
... On the other hand, there is a set of "wet chemistry" methods [23] that allows to synthesize REO in a nanostructured state, including the sol-gel method [24][25][26], hydrothermal synthesis [27][28][29][30], co-precipitation approach [31][32][33], and some others [34][35][36][37]. Solution combustion method [38][39][40][41][42][43] makes it possible to synthesize REO nanoparticles in both stable and metastable structural forms [44][45][46] and even in an amorphous state [47]. This method is based on a redox reaction starting from the reaction solution and self-sustaining due to the thermal effect of the combustion reaction [48][49][50]. ...
... ones. Generalized type of patterns as a function of G/N ratio is attributed to combustion modes at the synthesis stage [38,41]: ...
In this paper, nanopowders based on iron-deficient Sc2-xFexO3 (x = 0.17–0.47) nanocrystals with bixbyite structure and crystallite size of 3.7–38.9 nm were successfully synthesized via solution combustion. Variable glycine-to-nitrate (G/N) ratio was the main controlling factor. A wide range of experimental and computational methods were used to analyze the impact of spatial constraints on the resulting solid-state products. It was found that solution combustion mode greatly influenced on the temperature and gaseous products in the reaction zone. Volume (G/N = 0.4–0.8, Tmax = 1179–1511 °C), self-propagating (G/N = 1.0–1.4, Tmax = 614–957 °C) or smoldering (G/N = 0.2, Tmax = 443 °C) combustion modes were acquired during the synthesis depending on G/N ratio. It was shown that the formation of impurity phases of am-Fe2O3 (Tmax < 850 °C), c-Fe3O4 (900 °C < Tmax < 1500 °C) or c-FeO (Tmax > 1500 °C) was possible, depending on the combustion temperature. Besides, the combustion mode affected the porous and surfacial structure of resulting mesoporous nanopowders – specific surface area and total pore volume varied in ranges of 1.7–82.8 m²/g and 0.0088–0.1538 cm³/g, consequently. Chemical composition and unit cell parameters of Sc2-xFexO3 showed the positive deviation from Vegard's law. The average sizes of the interpore thickness (h) depending on G/N ratio were found from values of specific surface area and pycnometric density of nanopowders, which made it possible to establish the presence of spatial constraints for the crystals' growth of Sc2-xFexO3 at h values below 10 nm. Analysis of aspect (h/D) ratio allowed to determine synthetic parameters which led to mono- or polycrystalline structure of interpore space in resulting Sc2-xFexO3-based nanopowders. The results and patterns established in this paper allowed to synthesize a new type of foam-like functional materials based on rare-earth ferrites.
... Complex oxides of different classes provide a basis for various functional materials used in energy transformation devices (photovoltaic devices, solid-oxide fuel cells) [1][2][3][4][5][6][7], sensorics [8,9], magnetic, superconducting, and microwave equipment [10][11][12][13][14][15][16][17][18][19], catalysis [18,[20][21][22][23][24][25][26][27][28][29][30][31], and other areas [8,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51]. Nanosized complex oxides obtained by methods of so-called soft chemistry are commonly used to produce the above materials [1,5,. ...
... Low-molecular-weight compounds and polymers are used as organic oxidizable components of precursors. They include, in particular, glycine [11-13, 22, 32, 35-37, 39] and other amino acids, glycerol [3], urea [7,27,28,43,44], citric [4,7,17,26] or tartaric acid, cellulose, polyvinyl alcohol [23,24,51], polyvinylpyrrolidone [46,51], polyacrylamide, etc. Moreover, these components can prevent salt crystallization during solvent removal, due to complexation including [51][52][53][54][55][56][57]. ...
... Low-molecular-weight compounds and polymers are used as organic oxidizable components of precursors. They include, in particular, glycine [11-13, 22, 32, 35-37, 39] and other amino acids, glycerol [3], urea [7,27,28,43,44], citric [4,7,17,26] or tartaric acid, cellulose, polyvinyl alcohol [23,24,51], polyvinylpyrrolidone [46,51], polyacrylamide, etc. Moreover, these components can prevent salt crystallization during solvent removal, due to complexation including [51][52][53][54][55][56][57]. ...
... Some aspects of increasing the rate of phase transformations were considered in [2,[6][7][8][9][10][11][12][13]. As examples of fast-flowing processes of formation of new phase crystalline particles, certain dehydration reactions under hydrothermal conditions [14][15][16][17][18][19], combustion reactions [20][21][22][23][24][25][26][27][28][29][30], as well as condensation of certain crystalline products from the gas phase [31][32][33][34], can be cited. It is crucial to highlight the processes whose high-speed results from the fact that the formation and growth of particles of a new phase is determined by the transfer of matter in the form of clusters with a large number of atoms [2,[35][36][37][38][39][40][41][42]. ...
... In cases where the layer of foam bubble walls in which phase formation occurs is thin, it can be considered as a quasi-two-dimensional microreactor or, at least, a nanoreactor. An example of such phase formation can be the synthesis of oxide nanoparticles obtained by the method of "solution combustion" [23,25,28,29,[246][247][248][249][250][251][252][253][254] under a certain regime of this process [255,256]. Such a "solution combustion" mode can be considered as an independent method of obtaining nanoparticles or as the method of "foam combustion" schematically depicted in Fig. 4. The effect of the self-organization of quasi-two-dimensional thin layers as quasi-two-dimensional nanoreactors upon the production of nanoparticles by the "foam combustion" method of the reduction of particle growth rate is associated with the walls (boundaries) of the layers blocking of the transfer of matter to the formed particles (Fig. 4). ...
A systematic analysis of literature data concerning the influence of methods and conditions of synthesis on the possibility of self-organization of particle growth restrictions during chemical reactions of solid phase has been conducted. The prospects of using such methods to obtain nano-crystalline phases are shown. It is demonstrated that a disadvantage of such methods of synthesis is the risk of forming precursor phases instead of target products. To avoid such an outcome, several methods of synthesis are proposed. Based on the analysis of literature data, examples of the transformation of precursor nanoparticles into nanocrystals of target phases are classified and presented. A scheme that allows optimal combination of synthesis methods to obtain nano-crystalline particles of a given composition, structure, size, and shape is designed.
... The morphology of the glycine-nitrate combustion product (as-prepared sample) according to SEM data ( Fig. 1 b) is sponge-like and the sample has a developed surface and a porous structure. This morphology and microstructure are characteristic for oxide materials obtained by SCS in case of a significant deviation of the composition of the reaction medium (in this case, the ratio of glycine and nitrates) from the stoichiometric composition and was previously observed for both simple [62,63] and complex oxides [64e66]. These features of products are associated with an increased release of gaseous reaction products generated by an excess of fuel (for glycine -CO, CO 2 , etc.) or an oxidizer (for nitrate groups -N 2 O, N 2 , NO, NO 2 , etc.) in comparison with reactions occurring in stoichiometric mode, during which the evolution of gaseous products is relatively small [67]. ...
This work reports an original approach to the synthesis of composite “core-shell” nanoparticles of o-EuFeO3@am-EuFeO3 via solution combustion synthesis (SCS) followed by heat treatment in the air. PXRD, 57Fe and 151Eu Mössbauer spectroscopy, FTIR, DSC-TGA, SEM-EDX, TEM-SAED and vibrating-sample magnetometry were used to analyze the as-prepared and heat-treated samples. It was shown that the formation of amorphous am-EuFeO3 “shell” on the surface of crystalline o-EuFeO3 “cores” arises from the partial carbonatization of europium oxide during the solution combustion. It was found that the average crystallite size of o-EuFeO3 “cores” (37-92 nm) and thickness of am-EuFeO3 “shell” (1-10 nm) can be easily varied through the simple temperature change of heat treatment in the range of 500-900°C. Acquired composite nanoparticles o-EuFeO3@am-EuFeO3 demonstrate uniform isometric morphology with a well distinct core and shell. Magnetometry results indicate the paramagnetic behavior of composite nanoparticles in a wide range of temperatures and applied magnetic fields that contradict the Mössbauer spectroscopy results showing the magnetic ordering of Fe-sublattice of o-EuFeO3 “cores”. Thus, the results of this work confirm the possibility of obtaining a new class of rare earth orthoferrite nanomaterials with the core-shell structure that can have promising functional applications.
... Current works in the field of development of nanostructured converters and storage devices are mainly focused on the problems of physical and chemical formation of structural and functional characteristics and the development of methods for technological support of the synthesis of nanodisperse and nanoporous materials [222][223][224][225][226][227][228][229][230][231][232][233][234]. Also their technological applications in different types of converters, in particular, thermoelectric, solar and wind generators, fuel cells, batteries and galvanic batteries, supercapacitors and other devices, up to systems of high-temperature superconductivity are being discussed [235][236][237][238][239][240][241][242][243][244][245][246][247][248]. ...
... The combustion method of gel-like media in high-speed kinetic mode [201,208,224,225,232,248,294] is an alternative to the described synthesis method, which proceeds in a relatively slow diffusion mode [216][217][218][219][220][221]262,293,FIG. 22. Scheme of conjugation mechanism of LnAlO 3 (P) and rock salt MO (RS) blocks, which form the one-layered Ruddlesden-Popper phases structure. ...
In this paper, the achievements, problems and prospects of creating personalized energy systems based on nanostructured materials are analyzed. Various concepts of developing methods and ways of personalized energy provision for autonomous human survival in remote natural habitats, emergencies of natural disasters and technogenic catastrophes when a centralized power supply is unavailable or to reduce the economic and environmental costs of remote energy production and transportation are also considered. The possibilities and limitations of using traditional and renewable alternative energy sources, processes and devices for extracting, storing and converting their energy into the necessary consumer forms due to fundamental physical laws are discussed as well. The article covers the new nanostructured materials with special functional properties for personalized energy systems development. The mechanisms for the formation of the required nanostructures in synthesized materials, especially those with a high content of fractal interfacial formations, are considered as well as methods for studying their structural and phase characteristics that determine the achievability of the specified parameters of model converters and energy storage devices.
