The Poly-Substituted M-Type Hexaferrite Crystals Growth

2019 ◽  
Vol 946 ◽  
pp. 186-191 ◽  
Author(s):  
O.V. Zaitseva ◽  
D.A. Vinnik ◽  
Evgeny A. Trofimov
Keyword(s):  
Solid Solutions ◽  
Configurational Entropy ◽  
Crystalline Solid ◽  
Structural Stabilization ◽  
High Entropy ◽  
Crystal Matrix ◽  
Composition And Structure ◽  
Ferrite Structure ◽  
Oxide Phases ◽  
Matrix Components

In the presented article the possibility analysis of highly entropic oxide phases composition and structure formation was performed. Moreover, the studies devoted to the production of substituted single crystals with the M-type hexa-ferrite structure were carried out. The experiments were conducted to studying the possibility of obtaining oxide high-entropy crystalline solid solutions with the M-type hexa-ferrites structure. As the result of the crystallized samples investigation, the microcrystalline highly entropic Ba (Fe,Mn,Ni,Ti,Al)12O19 and (Ba,Pb,Sr)(Fe,Mn,Ti,Ni,Al)12O19 phases appearing was detected. Based on the obtained data, it is possible to consider that the poly-substituted crystals growth with M-type hexa-ferrite structure. The structural stabilization is promoted by high values of the configurational entropy of the crystal matrix components mixing.

The Creation of Multicomponent Octahedral Crystals with Spinel Structure Using Solid-Phase Synthesis in the Al2O3-BaO-CuO-Fe2O3-Mn2O3-NiO-SrO-TiO2- ZnO and Al2O3-BaO-CuO-Fe2O3-NiO-SrO-TiO2-WO3- ZnO Systems

2020 ◽  
Vol 989 ◽  
pp. 341-346
Author(s):  
O.V. Zaitseva ◽  
Vladimir E. Zhivulin ◽  
D.E. Zhivulin
Keyword(s):  
Experimental Study ◽  
Spinel Structure ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Synthesis Method ◽  
Configurational Entropy ◽  
Phase Synthesis ◽  
High Entropy ◽  
Barium Strontium ◽  
Oxide Phases

This paper presents the results of an experimental study of the possibility of high-entropy oxide phases creation using the of solid-phase synthesis method in the Al2O3–BaO–CuO–Fe2O3–Mn2O3–NiO–SrO–TiO2–ZnO and Al2O3–BaO–CuO–Fe2O3–NiO–SrO–TiO2–WO3–ZnO systems. As a result of the study, a microcrystalline octahedral multicomponent phase was found in the crystallized sample. Judging by the composition, this phase has a spinel structure and is characterized (judging by the components concentrations and its ratio) by rather high values of the mixing configurational entropy. It is shown that barium, strontium and tungsten are not included in this phase in appreciable amounts. The obtained results indicate the possibility of synthesizing high-entropic spinels using these Al2O3–CuO–Fe2O3–Mn2O3–NiO–TiO2–ZnO systems.

High-entropy-stabilized chalcogenides with high thermoelectric performance

Science ◽  
2021 ◽  
Vol 371 (6531) ◽  
pp. 830-834 ◽  
Author(s):  
Binbin Jiang ◽  
Yong Yu ◽  
Juan Cui ◽  
Xixi Liu ◽  
Lin Xie ◽  
...  
Keyword(s):  
Thermoelectric Materials ◽  
Performance Optimization ◽  
Figure Of Merit ◽  
Phonon Scattering ◽  
Waste Heat ◽  
Configurational Entropy ◽  
Thermoelectric Performance ◽  
Structural Stabilization ◽  
High Entropy ◽  
Thermoelectric Conversion

Thermoelectric technology generates electricity from waste heat, but one bottleneck for wider use is the performance of thermoelectric materials. Manipulating the configurational entropy of a material by introducing different atomic species can tune phase composition and extend the performance optimization space. We enhanced the figure of merit (zT) value to 1.8 at 900 kelvin in an n-type PbSe-based high-entropy material formed by entropy-driven structural stabilization. The largely distorted lattices in this high-entropy system caused unusual shear strains, which provided strong phonon scattering to largely lower lattice thermal conductivity. The thermoelectric conversion efficiency was 12.3% at temperature difference ΔT = 507 kelvin, for the fabricated segmented module based on this n-type high-entropy material. Our demonstration provides a paradigm to improve thermoelectric performance for high-entropy thermoelectric materials through entropy engineering.

scholarly journals New high-entropy oxide phases with the magnetoplumbite structure

2021 ◽  
Vol 1014 (1) ◽  
pp. 012062
Author(s):  
V E Zhivulin ◽  
E A Trofimov ◽  
A Yu Starikov ◽  
S A Gudkova ◽  
A Yu Punda ◽  
...  
Keyword(s):  
High Entropy ◽  
Oxide Phases

scholarly journals A Review on the High Temperature Strengthening Mechanisms of High Entropy Superalloys (HESA)

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5835
Author(s):  
Malefane Joele ◽  
Wallace Rwisayi Matizamhuka
Keyword(s):  
High Temperature ◽  
Configurational Entropy ◽  
Extended Period ◽  
Theoretical Models ◽  
Intermetallic Phases ◽  
Processing Route ◽  
Strengthening Mechanisms ◽  
High Entropy ◽  
Use Of Resources ◽  
The Impact

The studies following HEA inceptions were apparently motivated to search for single-phase solid solution over intermetallic phases, accordingly made possible by the concept of high configurational entropy. However, it was realised that the formation of intermetallic phases in HEAs is prevalent due to other criterions that determine stable phases. Nonetheless, recent efforts have been directed towards attributes of microstructural combinations. In this viewpoint, the techniques used to predict microstructural features and methods of microstructural characterisation are elucidated in HESA fields. The study further analyses shortcomings regarding the design approaches of HESAs. A brief history is given into how HESAs were developed since their birth, to emphasize the evaluation techniques used to elucidate high temperature properties of HESAs, and the incentive thereof that enabled further pursuit of HESAs in the direction of optimal microstructure and composition. The theoretical models of strengthening mechanisms in HEAs are explained. The impact of processing route on the HESAs performance is analysed from previous studies. Thereafter, the future of HESAs in the market is conveyed from scientific opinion. Previous designs of HEAs/HESAs were more based on evaluation experiments, which lead to an extended period of research and considerable use of resources; currently, more effort is directed towards computational and theoretical methods to accelerate the exploration of huge HEA composition space.

The Kinetic Ordering and Growth Dissymmetrisation in Crystalline Solid Solutions

ChemInform ◽  
2007 ◽  
Vol 38 (18) ◽  
Author(s):  
A. G. Shtukenberg ◽  
Yu. O. Punin ◽  
O. V. Frank-Kamenetskaya
Keyword(s):  
Solid Solutions ◽  
Crystalline Solid

scholarly journals Bulk high-entropy nitrides and carbonitrides

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Olivia F. Dippo ◽  
Neda Mesgarzadeh ◽  
Tyler J. Harrington ◽  
Grant D. Schrader ◽  
Kenneth S. Vecchio
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Configurational Entropy ◽  
Temperature Stability ◽  
High Hardness ◽  
Valence Electron Concentration ◽  
High Temperature Stability ◽  
High Entropy ◽  
Rule Of Mixtures ◽  
Traditional Ceramics

AbstractHigh-entropy ceramics have potential to improve the mechanical properties and high-temperature stability over traditional ceramics, and high entropy nitrides and carbonitrides (HENs and HECNs) are particularly attractive for high temperature and high hardness applications. The synthesis of 5 bulk HENs and 4 bulk HECNs forming single-phase materials is reported herein among 11 samples prepared. The hardness of HENs and HECNs increased by an average of 22% and 39%, respectively, over the rule-of-mixtures average of their monocarbide and mononitride precursors. Similarly, elastic modulus values increased by an average of 17% in nitrides and 31% in carbonitrides over their rule-of-mixtures values. The enhancement in mechanical properties is tied to an increase in the configurational entropy and a decrease in the valence electron concentration, providing parameters for tuning mechanical properties of high-entropy ceramics.

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