Crystallization behavior and morphological features of YFeO3 nanocrystallites obtained by glycine-nitrate combustion

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Varying glycine to nitrate ratio in the initial solution the powders based on nanocrystalline LaFeO 3 were synthesized by solution combustion synthesis. The powders were studied by X-ray diffractometry, scanning electron microscopy, adsorption analysis and helium pycnometry. The average crystallite size of the synthesized LaFeO 3 nanocrystals ranged from 18±2 to 85±9 nm, and the specific surface area of the nanopowders based on them ranged from 8 to 33 m 2 /g. Based on the results, the influence of redox composition of the reaction solution on the nature of the combustion processes, as well as the composition, structure and properties of LaFeO 3 nanocrystals were analyzed. Here, it wasshown, that the nanopowders have specific microstructure in terms of monocrystalline nanoscale layers of lanthanum orthoferrite, therefore it is allowed to consider them as a promising base for catalytically and magnetically functional materials.

Section: Materials Characterizationmentioning

confidence: 99%

Peculiarities of LaFeO3 nanocrystals formation via glycine-nitrate combustion

Bachina¹,

Иванов²,

Попков³

2017

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“…Since the previous section addressed the occurrence of charges in precursors, we should comment on the ability to control the properties of materials using this phenomenon. There are ratios of organic components and nitrates which correspond to the most intensive SCS flow and the maximum thermal generation during the reaction (see, for example [94,96,112,118,213]). However, more significant charge accumulation was observed in compositions containing a substantial excess of the organic component.…”

Section: Oxide Materials Production By Scsmentioning

confidence: 99%

“…One of the features of oxide material synthesis from organic-inorganic compositions is that the main or a substantial material portion formed in the combustion can be amorphous [95,96,98,99,126,169,197,198]. This, in particular, results in the possibility to significantly reduce the temperature of additional thermal treatment for final production.…”

Section: Oxide Materials Production By Scsmentioning

confidence: 99%

“…We should note here that these impurity phases do not interfere with the successful use of materials in many cases [126,130,158,160,165,169,201,212], although it is sometimes necessary to make the material be single-phase [94,96,99,106,107,112,118,159,169]. Heterogeneous solid-phase systems are used in catalysis where the impurity phases often play the role of promoters and co-catalysts, as in the silver-inclusive lanthanum manganites [126,130,158,160].…”

Section: Oxide Materials Production By Scsmentioning

confidence: 99%

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Oxide material synthesis by combustion of organic-inorganic compositions

Ostroushko¹,

Русских²

2017

This review analyzes and summarizes the research results for oxide material synthesis by combustion of organic-inorganic mixtures. We have outlined the range of physical and chemical factors influencing the precursor processes and the oxide material synthesis itself, as well as have shown the ways and options to control these processes and nanoscale materials' properties. We have highlighted several issues concerning the analysis methods for the resulting materials and processes. We have exemplified the practical implementation of the methods under discussion.

“…Crystal growth can be reduced by using special synthetic methods, which include, in particular, soft chemistry methods, when synthesis proceeds at relatively low temperatures [36][37][38][39][40][41][42][43][44][45][46][47][48][52][53][54][55][56][57][58][59]. Another group of methods that includes, for example, solution combustion, self-propagating high-temperature synthesis (SHS), autocatalytic and other fast solidstate reactions, is based on the use of rapid synthesis [49][50][51][60][61][62][63][64][65][66][67][68][69][70][71]. Crystal growth can often be restricted by using nano-and microreactors, or synthesis methods that use spatial constraints [63,64,[72][73][74][75][76][77][78][79][80]…”

Section: Introductionmentioning

confidence: 99%

The minimum size of oxide nanocrystals: phenomenological thermodynamic vs crystal-chemical approaches

Almjasheva¹,

Ломанова²,

Попков³

et al. 2019

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The minimum crystallite size in a group of oxides has been analyzed as a function of their synthesis conditions, critical nucleus size and the crystal structure parameters. Nanocrystals were synthesized by solution combustion, hydrothermal synthesis and heat treatment in air of the precipitated hydroxides. Aluminum and iron oxides, titania and zirconia, cobalt ferrite, AFeO 3 ferrites (A = Bi, RE), Aurivillius phases Bi m+1 Ti 3 Fe m−3 O 3m+3 (m = 3 -9), as well as solid solutions based on these phases were chosen as the objects of the study. The presence of a correlation between the crystalline oxide unit cell parameters and the synthesized crystals minimum size is shown. A conclusion was made about the impossibility to use only the thermodynamic concept of the critical nucleus for determining the minimum possible particle size of a new phase in some cases of oxide nanocrystals synthesis. The paper demonstrates a necessity to use crystal-chemical criteria that complement the methods of phenomenological thermodynamics and kinetics for determining the minimum possible particle size of the resulting crystalline oxide phases synthesized under the considered conditions.