Phase Separation during the Topotactic Reduction of the Pyrochlore Y2Ti2O7

Hayward, Michael A.

doi:10.1021/cm048220p

Cited by 29 publications

(16 citation statements)

References 12 publications

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“…X-ray powder diffraction data collected from samples could be indexed on the basis of monoclinic unit cells (space group P2 1 /c) and gave lattice parameters as shown in Table 1 in good agreement with previously reported values for these phases [6,10]. CaH 2 has been used in as a solid-state reducing agent to bring about the topotactic reduction of complex transition metal oxides according to reaction Scheme 1 [11]. Samples were heated at the desired reaction temperature (see Table 2) for two periods of 2 days, with intermediate regrinding.…”

Section: Introductionsupporting

confidence: 84%

Anion vacancy ordering in Sr7Mn4O15−x phases

O’Malley

Lockett

Hayward

2007

Journal of Solid State Chemistry

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Section: Introductionsupporting

confidence: 84%

Anion vacancy ordering in Sr7Mn4O15−x phases

O’Malley

Lockett

Hayward

2007

Journal of Solid State Chemistry

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“…Important examples exist in a wide range of compounds including layered intercalation hosts [3][4][5][6] fast ion conductors 7,8 and electronically-active materials. [9][10][11][12] These routes typically involve preparing a precursor compound at high temperature and then modifying this material; by treatment with a salt 4 solution 3 or electrochemically 4 to manipulate the cations or with a reducing 9,10,13 or oxidising agent 14 to adjust the occupancy of the anion sublattice.…”

Section: Introductionmentioning

confidence: 99%

Spontaneous formation of crystalline lithium molybdate from solid reagents at room temperature

2010

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Lithium molybdate has been prepared by grinding LiOH x H(2)O with MoO(3) in air at room temperature. X-Ray powder diffraction data show that the formation of highly crystalline Li(2)MoO(4) is largely complete after 10 min. The phenacite structure of this material is the same as that derived from an X-ray diffraction study of a single crystal obtained from aqueous solution [R3; a = 14.3178(14) A, c = 9.5757(9) A]. Anhydrous lithium hydroxide fails to give the same reaction indicating that the water of crystallisation of LiOH x H(2)O is a vital component in this rapid synthesis. Differential scanning calorimetry measurements show that this reaction can proceed spontaneously between the two stable solid reagents at sub-ambient temperatures and is driven by the liberation of water from the crystalline lattice. Lithium molybdate prepared in this manner has significantly smaller and more regularly shaped particles than samples prepared by other synthetic methods.

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“…The oxygen deficiency could be an artefact of APT and is most likely dependent on the particle chemistry and acquisition parameters [38]. It should be noted that the anion-deficient phases of Y 2 Ti 2 O 6.48 and Y 2 Ti 2 O 5.91 can be produced by reducing the pyrochlore Y 2 Ti 2 O 7 [43] and so these structures could be stabilized by a low oxygen activity during consolidation.…”

Section: Size Distributionmentioning

confidence: 99%

Effect of Ti and Cr on dispersion, structure and composition of oxide nano-particles in model ODS alloys

et al. 2015

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a b s t r a c tThree model ODS alloys (Fe-0.3Y 2 O 3 , Fe-0.2Ti-0.3Y 2 O 3 and Fe-14Cr-0.2Ti-0.3Y 2 O 3 ) were prepared by ball milling and then hot extrusion to study the effect of Ti and Cr on the size, distribution, crystal structure and composition of the nano-oxide particles. All alloys were characterized by high resolution transmission electron microscopy (HRTEM), atom probe tomography (APT) and synchrotron-X-ray diffraction (S-XRD) to determine the distribution, structure and composition of the oxide nanoparticles samples. The median particle sizes were 9.6 nm, 7.7 nm and 3.7 nm for the Fe-Y 2 O 3 , Fe-Ti-Y 2 O 3 and Fe-Cr-Ti-Y 2 O 3 alloys, respectively, so the presence of Ti resulted in a significant reduction in oxide particle diameter and the addition of Cr gave a further reduction in size. In the Fe-0.3Y 2 O 3 alloy, the particles are found to be bcc Y 2 O 3 , whereas in the other two alloys (Fe-Ti-0.3Y 2 O 3 and Fe-Cr-Ti-Y 2 O 3 ), the oxide particles were found to be structurally consistent with both orthorhombic Y 2 TiO 5 and fcc Y 2 Ti 2 O 7 . Detailed APT studies showed Cr shells around oxide particles of all sizes in the Fe-Cr-Ti-Y 2 O 3 alloy, that a range of cluster compositions are present and that the particle chemistry varies with cluster size. We show that the addition of Cr has a strong effect on both the size and stoichiometry of the particles.

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Phase Separation during the Topotactic Reduction of the Pyrochlore Y₂Ti₂O₇

Cited by 29 publications

References 12 publications

Anion vacancy ordering in Sr7Mn4O15−x phases

Anion vacancy ordering in Sr7Mn4O15−x phases

Spontaneous formation of crystalline lithium molybdate from solid reagents at room temperature

Effect of Ti and Cr on dispersion, structure and composition of oxide nano-particles in model ODS alloys

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