Oxide Precipitate Nucleation via Coherent Seed -Oxide Phases

Oxide phases having the hollandite structure have been identified in multiphase ceramic waste forms being developed for radioactive waste disposal. High resolution studies of phases in the waste forms described in Ref. [2] were initiated to examine them for fine scale structural differences compared to natural mineral analogs. Two hollandites were studied: a (Ba,Cs,K)-titan-ate with minor elements in solution that is produced in the waste forms, and a synthesized BaAl2Ti6O16 phase containing ∼ 4.7 wt% Cs2O. Both materials were consolidated by hot pressing at temperatures above 1100°C. Samples for high resolution microscopy were prepared both by ion-milling (7kV argon ions) and by crushing and dispersing the fragments on holey carbon substrates. The high resolution studies were performed in a JEM 200CX/SEG operating at 200kV.

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Microstructure and microanalysis of sintered Fe-Nd-B permanent magnets

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178082 ◽

1990 ◽

Vol 48 (4) ◽

pp. 990-991

Author(s):

Mahesh Chandramouli

Keyword(s):

Electron Microscope ◽

Liquid Phase ◽

Permanent Magnets ◽

Phase Distribution ◽

Energy Dispersive Spectrometer ◽

Nucleation And Growth ◽

Liquid Phase Sintering ◽

Domain Wall Energy ◽

Oxide Phases ◽

Scanning Electron

Magnetization reversal in sintered Fe-Nd-B, a complex, multiphase material, occurs by nucleation and growth of reverse domains making the isolation of the ferromagnetic Fe14Nd2B grains by other nonmagnetic phases crucial. The magnets used in this study were slightly rich in Nd (in comparison to Fe14Nd2B) to promote the formation of Nd-oxides at multigrain junctions and incorporated Dy80Al20 as a liquid phase sintering addition. Dy has been shown to increase the domain wall energy thus making nucleation more difficult while Al is thought to improve the wettability of the Nd-oxide phases.Bulk polished samples were examined in a JEOL 35CF scanning electron microscope (SEM) operated at 30keV equipped with a Be window energy dispersive spectrometer (EDS) detector in order to determine the phase distribution.

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New high-entropy oxide phases with the magnetoplumbite structure

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1014/1/012062 ◽

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

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Effects of Carbon Concentration Upon Oxygen Precipitation in Cz Si

MRS Proceedings ◽

10.1557/proc-104-201 ◽

1987 ◽

Vol 104 ◽

Author(s):

S. Hahn ◽

M. Arst ◽

K. N. Ritz ◽

S. Shatas ◽

H. J. Stein ◽

...

Keyword(s):

Carbon Content ◽

Carbon Concentration ◽

High Carbon ◽

High Carbon Content ◽

Oxygen Precipitation ◽

Oxygen Precipitate ◽

High Carbon Concentration ◽

Precipitation Characteristics ◽

C Complex ◽

Oxide Precipitate

ABSTRACTEffects of high carbon concentration upon oxygen precipitate formation in Cz silicon have been investigated by combining various furnace and rapid thermal annneals. Even though oxide precipitate density increases with increasing carbon levels, Cs, synchrotron radiation section topographs of processed high carbon content wafers (Cs ∼ 4ppma) exhibit Pendellosung fringes, indicating a strain free bulk state. Our optical microscopic data have also shown very few defect etch features inside the bulk. A model based upon a direct coupling of both SiO2 and Si-C complex formation reactions is used to explain rather unique oxygen precipitation characteristics in the high carbon content Cz Si materials.

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