Anomalous crystal chemistries of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mo>→</mml:mo></mml:mrow><mml:mrow /><mml:mrow><mml:mn>111</mml:mn></mml:mrow><mml:mrow /><mml:mrow /><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>111</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>Cd and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow

Adams, James M.; Catchen, Gary L.

doi:10.1103/physrevb.50.1264

Cited by 42 publications

(28 citation statements)

References 10 publications

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“…The quadrupole frequency is practically independent of the thermal history; heating to and cooling from 1400 K produce the same linear trend q ͑T͒ = q ͑0͒͑1−AT͒ with q ͑0͒ = 798.9͑5͒ MHz and A = 2.96͑7͒ ϫ 10 −5 K −1 . These values are in fair agreement with those obtained for 181 Ta in coarse-grained 13 and single crystal 15 TiO 2 .…”

Section: Discussionsupporting

confidence: 81%

“…With increasing temperature, the QI parameters of the latter component evolve towards those of 181 Ta in coarse-grained rutile TiO 2 . 13 This fraction will therefore be denominated as "rutile" fraction. The main results of the analysis are collected in Figs.…”

Section: Resultsmentioning

confidence: 99%

“…͑2͒ to the 300 K spectrum in In sample I, an oscillatory structure starts to appear at T ϳ 500 K and in sample II at T ϳ 800 K. With further increase of temperature, the oscillation amplitudes grow and at T ϳ 1400 K the PAC spectra of 181 Ta in the two samples n-Ti͑Hf͒O 2 have become identical to that of 181 Ta in coarsegrained rutile TiO 2 . 13 From 500 K ͑sample I͒ or 800 K ͑sample II͒ onwards, two components or fractions are necessary to describe the PAC spectra, one characterized by the broad frequency found after the synthesis ͑"disordered" fraction͒ and the other subjected to a sharper QI, which gives rise to the visible oscillations. With increasing temperature, the QI parameters of the latter component evolve towards those of 181 Ta in coarse-grained rutile TiO 2 .…”

Section: Resultsmentioning

confidence: 99%

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Structure and grain growth of TiO2 nanoparticles investigated by electron and x-ray diffractions and Ta181 perturbed angular correlations

Schlabach

Szabó

Vollath

et al. 2006

Journal of Applied Physics

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Bare and coated TiO 2 nanoparticles with particle sizes d Ͻ 5 nm have been synthesized in a microwave plasma process. Structural properties of these materials have been investigated by transmission electron microscopy, x-ray diffraction, and perturbed angular correlation ͑PAC͒ measurements of the electric quadrupole interaction ͑QI͒ at the probe nucleus 181 Ta on the metal site of TiO 2 at temperatures 290ഛ T ഛ 1450 K. The electron diffraction of the uncoated nanoparticles in the as-synthesized state reflects long range order in the Ti sublattice. Depending on the particles size, either the anatase or the rutile phase of TiO 2 was found. Anatase appears to be the stable form of nanocrystalline TiO 2 below d ϳ 10 nm. The PAC spectra of these nanocrystalline oxides are characterized by a broad distribution of strong quadrupole interactions, indicating a strongly disordered oxygen environment of the metal sites. Upon annealing, the grain size grows from d Ͻ 5 nm after synthesis to d Ͼ 100 nm after 1300 K. PAC spectra taken in the same temperature range show that with increasing temperature, the initially disordered state transforms to well-ordered rutile TiO 2 . The data suggest a critical grain size of d ϳ 10 nm for the onset of the ordering process. The spectra of coarse-grained TiO 2 are reached at a particle size d ജ 30 nm. In n-TiO 2 coated with Al 2 O 3 and ZrO 2 both the cores and the coatings were found to grow with increasing temperature; the cores of the coated particles, however, grow much less than those of the noncoated particles. The PAC method was used to investigate the QI in both TiO 2 cores and in the ZrO 2 coating of n-TiO 2 / ZrO 2 at different temperatures. These data suggest that although the coated particles grow with temperature, the ordering process is obstructed, possibly by a solid state reaction between the TiO 2 kernels and the coatings.

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Section: Discussionsupporting

confidence: 81%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Structure and grain growth of TiO2 nanoparticles investigated by electron and x-ray diffractions and Ta181 perturbed angular correlations

Schlabach

Szabó

Vollath

et al. 2006

Journal of Applied Physics

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“…This was measured by others. However the method of sample preparation in our case is different from that in ref [16].…”

Section: Discussionmentioning

confidence: 74%

“…We first measured the hyperfine parameters for the bulk anatase and rutile forms of TiO 2 [15]. The measurement for the rutile is a repetition except the difference in the preparation of the sample mentioned elsewhere [16]. The parameters thus obtained after annealing the sample at different temperatures have been used to address surface/bulk mass transfer and the different aspects of the phase transformation taking place in 70 nm TiO 2 .…”

Section: Introductionmentioning

confidence: 99%

Study of surface-bulk mass transport and phase transformation in nano-TiO2 using hyperfine interaction technique

Banerjee¹,

Das²,

Thakare³

et al. 2010

Journal of Physics and Chemistry of Solids

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Phase transition from anatase to rutile for the 70nm TiO 2 crystallite has been investigated by annealing at different temperatures followed by TDPAC measurement of these TiO 2 crystallites adsorbed with 181 Hf tracer. The width of the peaks in XRD spectra for TiO 2 crystallites annealed at different temperatures indicates the growth of the crystallites with temperature. The samples annealed upto 823K for 4hrs showed no phase transition, except the growth of the crystallites. However, it showed phase transition at the same temperature (823K), when annealed for longer duration. Annealing for shorter duration at 1123K showed phase transition. 181 Hf tracer adsorbed on 70 nm anatase TiO 2 is found to be in different polymorphs (anatase & rutile) formed during annealing process. Surface to bulk mass-transfer is found to play a significant role in the phase transition process.

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Ab initio Study of the Temperature Dependence of the EFG at Cd Impurities in Rutile TiO2

Errico

Hfi/Nqi 2004

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Anomalous crystal chemistries of the→111111Cd and

Cited by 42 publications

References 10 publications

Structure and grain growth of TiO2 nanoparticles investigated by electron and x-ray diffractions and Ta181 perturbed angular correlations

Structure and grain growth of TiO2 nanoparticles investigated by electron and x-ray diffractions and Ta181 perturbed angular correlations

Study of surface-bulk mass transport and phase transformation in nano-TiO2 using hyperfine interaction technique

Ab initio Study of the Temperature Dependence of the EFG at Cd Impurities in Rutile TiO2

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