In situ non-aqueous nucleation and growth of next generation rare-earth-free permanent magnets

2015 ◽  
Vol 17 (2) ◽  
pp. 1070-1076 ◽  
Author(s):  
Hyojung Yoon ◽  
Aoran Xu ◽  
George E. Sterbinsky ◽  
Dario A. Arena ◽  
Ziying Wang ◽  
...  
Keyword(s):  
Rare Earth ◽  
Room Temperature ◽  
Permanent Magnets ◽  
Bulk Material ◽  
Nucleation And Growth ◽  
Time Resolved ◽  
Energy Product ◽  
Formation Kinetics ◽  
Kinetics Of

In situ time resolved XAS measurements are applied to investigate the phase formation kinetics of metastable cobalt carbide nanoparticles using polyol reduction chemistry. The resulting material exhibits an energy product of greater than 20.7 kJ m−3 at room temperature before compaction, a vastly improved coercivity compared to pure bulk material.

Influence of oxygen partial pressure on the kinetics of YBa2Cu3O7−x formation

1994 ◽  
Vol 9 (2) ◽  
pp. 275-285 ◽  
Author(s):  
V. Milonopoulou ◽  
K.M. Forster ◽  
J.P. Formica ◽  
J. Kulik ◽  
J.T. Richardson ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
Decomposition Products ◽  
Time Resolved ◽  
X Ray ◽  
Formation Kinetics ◽  
Dimensional Diffusion ◽  
Diffusion Controlled ◽  
Gas Atmosphere ◽  
Kinetics Of

The YBa2Cu3O7−x formation kinetics from a spray-roasted precursor powder containing Y2O3, BaCO3, and CuO was followed via in situ, time-resolved x-ray diffraction as a function of gas atmosphere and temperature. In inert atmospheres, BaCO3 and CuO form BaCu2O2 which subsequently reacts with Y2O3 to form YBa2Cu3O6. However, YBa2Cu3O6 decomposes at temperatures exceeding 725 °C with Y2BaCuO5 being one of the decomposition products. In oxidizing atmospheres, YBa2Cu3O7−x formation involves the BaCuO2. At high temperatures (800–840 °C), oxygen increases the yield of YBa2Cu3O6. A nuclei growth model assuming two-dimensional, diffusion-controlled growth with second-order nucleation rate fits the experimental data.

In situ ellipsometric studies of formation kinetics of rare earth metal conversion coatings on magnesium alloy

2008 ◽  
Vol 5 (5) ◽  
pp. 1308-1311 ◽  
Author(s):  
Lingjie Li ◽  
Jinglei Lei ◽  
Shenghai Yu ◽  
Donghai He ◽  
Weijuan Qu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Magnesium Alloy ◽  
Rare Earth Metal ◽  
Earth Metal ◽  
Conversion Coatings ◽  
Formation Kinetics ◽  
Kinetics Of

scholarly journals In situ growth of SrFe12O19

2014 ◽  
Vol 70 (a1) ◽  
pp. C505-C505
Author(s):  
Cecilia Granados ◽  
Espen Bøjesen ◽  
Kirsten Jensen ◽  
Mogens Christensen
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Permanent Magnets ◽  
Elevated Pressure ◽  
Ex Situ ◽  
High Coercivity ◽  
Hydrothermal Conditions ◽  
Time Resolved ◽  
Kinetics Of

SrFe12O19 is a highly anisotropic ferrimagnetic compound with relatively high remanence and high coercivity, which is used in permanent magnets. Permanent magnets are everywhere in our daily life and they are responsible for the interconversion between motion and electricity in electrical components ranging from headphones to wind turbines. Three key parameters, important for making permanent magnets, are an anisotropic structure, size of the nanocrystallites and the microstructure. In situ X-ray powder diffraction has been used to follow the growth kinetics of SrFe12O19 under hydrothermal conditions. Synthesis of SrFe12O19 (Sr-Hexaferrite) nanocrystals by hydrothermal methods have the advantage of allowing exhaustive control of the reaction parameters. We have studied the growth and kinetics of SrFe12O19 by carring out time resolved synchrotron experiments at MAX-lab, Sweden. The experiments were carried out at elevated pressure (250 bar) and in temperatures ranging from 250 to 400 oC. The diffraction data allow us to follow the evolution of the crystallite size as function of temperature, time and composition. By controlling the composition of the precursor we can tailor the size of the nanocrystallites. The obtained data have shown that the synthesis takes place through a conversion of tiny hexagonal shaped FeOOH nanocrystallites into the SrFe12O19. Several ex situ studies under comparable conditions have been carried out to compare the magnetic properties and the obtained nanocrystallites have been investigated using high resolution laboratory powder diffraction data.

In situ observation of the martensitic transformation in (Mg,Y)-PSZ

1986 ◽  
Vol 44 ◽  
pp. 500-501
Author(s):  
R-R. Lee
Keyword(s):  
Martensitic Transformation ◽  
High Strength ◽  
Nucleation And Growth ◽  
In Situ Observation ◽  
Considerable Potential ◽  
Transmission Electron ◽  
Structural Applications ◽  
Applied Stresses ◽  
Kinetics Of

Partially-stabilized ZrO2 (PSZ) ceramics have considerable potential for advanced structural applications because of their high strength and toughness. These properties derive from small tetragonal ZrO2 (t-ZrO2) precipitates in a cubic (c) ZrO2 matrix, which transform martensitically to monoclinic (m) symmetry under applied stresses. The kinetics of the martensitic transformation is believed to be nucleation controlled and the nucleation is always stress induced. In situ observation of the martensitic transformation using transmission electron microscopy provides considerable information about the nucleation and growth aspects of the transformation.

In situ Time-Resolved Small-Angle X-ray Scattering Reveals the Formation Kinetics of Polyelectrolyte Complex Micelles

2019 ◽  
Author(s):  
Hao Wu ◽  
Jeffrey Ting ◽  
Siqi Meng ◽  
Matthew Tirrell
Keyword(s):  
Small Angle ◽  
Self Assembly ◽  
Electrostatic Interactions ◽  
Polyelectrolyte Complex ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Kinetics Of ◽  
Ray Scattering

We have directly observed the <i>in situ</i> self-assembly kinetics of polyelectrolyte complex (PEC) micelles by synchrotron time-resolved small-angle X-ray scattering, equipped with a stopped-flow device that provides millisecond temporal resolution. This work has elucidated one general kinetic pathway for the process of PEC micelle formation, which provides useful physical insights for increasing our fundamental understanding of complexation and self-assembly dynamics driven by electrostatic interactions that occur on ultrafast timescales.

Understanding the phase formation kinetics of nano-crystalline kesterite deposited on mesoscopic scaffolds via in situ multi-wavelength Raman-monitored annealing

2016 ◽  
Vol 18 (42) ◽  
pp. 29435-29446 ◽  
Author(s):  
Zhuoran Wang ◽  
Samir Elouatik ◽  
George P. Demopoulos
Keyword(s):  
Real Time ◽  
Phase Formation ◽  
Formation Kinetics ◽  
Nano Crystalline ◽  
Multi Wavelength ◽  
Real Time Information ◽  
Kinetics Of ◽  
Time Information ◽  
Annealing Method

The in situ Raman monitored annealing method is developed in this work to provide real-time information on phase formation and crystallinity evolution of kesterite deposited on a TiO2 mesoscopic scaffold.

Time-Resolved In Situ MAS NMR Monitoring of the Nucleation and Growth of Zeolite BEA Catalysts under Hydrothermal Conditions

2017 ◽  
Vol 56 (48) ◽  
pp. 15344-15347 ◽  
Author(s):  
Irina I. Ivanova ◽  
Yury G. Kolyagin ◽  
Ivan A. Kasyanov ◽  
Alexander V. Yakimov ◽  
Tatiana O. Bok ◽  
...  
Keyword(s):  
Nucleation And Growth ◽  
Mas Nmr ◽  
Hydrothermal Conditions ◽  
Time Resolved
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