A furnace for high temperature perturbed angular correlation measurements

Forker, M.; Herz, W.; Hütten, U.; Müller, Martin; Müsseler, R.; Schmidberger, J.W.; Simón, Daniel; Weingarten, A.; Bedi, S. C.

doi:10.1016/0168-9002(93)90711-p

Cited by 15 publications

(12 citation statements)

References 8 publications

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“…For the production of the PAC sources, noncompacted powder of Hf-doped n-TiO 2 ͑typically a few mg͒ was enclosed under vacuum into quartz tubes and irradiated in a flux of thermal neutrons of 5 ϫ 10 13 n/s cm 2 for times of the order of 24 h. The samples were mounted in a furnace designed for temperatures up to 2300 K. 25 The PAC spectra of the 133-482 keV cascade of 181 Ta were measured as a function of temperature in the range of 290ഛ T ഛ 1500 K. In most cases, the sample temperature was raised in steps of 50-100 K and after reaching 1500 K, decreased in similar steps back to room temperature. The spectra were taken with a standard four-detector setup equipped with fast BaF 2 scintillators.…”

Section: A Experimental Detailsmentioning

confidence: 99%

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: A Experimental Detailsmentioning

confidence: 99%

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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“…The PAC measurements were carried out with a standard four-detector BaF 2 setup in the temperature range 10 K ഛ T ഛ 1273 K. Temperatures T Ͻ 290 K were obtained with a closed-cycle He refrigerator, whereas temperatures T Ͼ 290 K were produced with an especially designed PAC furnace. 18 For the high temperature measurements, the samples were encapsulated under vacuum into small quartz tubes.…”

Section: A Sample Preparation and Equipmentmentioning

confidence: 99%

Electric field gradients in the rare earth–aluminium compoundsRAl2andRAl3studied by
Forker
¹
,
Presa
²

2007
Phys. Rev. B
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Perturbed angular correlation ͑PAC͒ spectroscopy has been used to investigate the electric field gradient ͑EFG͒ at the probe nucleus 111 In/ 111Cd in the paramagnetic phase of the rare earth ͑R͒-aluminium compounds RAl 2 for all R elements and Y and in RAl 3 for R = Gd, Tm, Yb, Lu. The nuclear electric quadrupole interaction ͑QI͒ between the EFG and the 111 Cd quadrupole moment was measured as a function of temperature in the range T C Ͻ T ഛ 1200 K. In the second half of the RAl 2 series and in the RAl 3 compounds, except for YbAl 3 , the quadrupole frequency q shows the monotonous decrease with increasing temperature normally observed with closed-shell probe nuclei in metallic systems. In the early members of the RAl 2 series, however, q ͑T͒ passes through a maximum at T ϳ 300 K. It is proposed that this unusual behavior reflects a contribution of the 4f shell of the R constituents to the EFG at the Al site which is quenched at higher temperatures by thermal averaging of the 4f quadrupole moment. In the intermediate-valence compound YbAl 3 the temperature dependence of the QI exhibits a shallow maximum which can be related to the temperature variation of the 4f hole occupation. Furthermore the PAC spectra provide information on the site preference of the Cd. The temperature dependence of the relaxation rates shows an Arrhenius behavior with jump activation enthalpies E A = 1.6͑1͒ eV for R = Tm, Lu and E A = 1.2͑1͒ eV for R =Yb.

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“…Temperatures were varied between 290 K and 1200 K with a PAC furnace described in Ref. [10], for temperatures 15 K ≤ T < 290 K we used a closed-cycle He refrigerator. Figs.…”

Section: Pac Equipment and Data Analysismentioning

confidence: 99%

“…This makes PAC a powerful tool when material properties at high temperatures are to be investigated by measurements of hyperfine interactions. PAC measurements up to T ∼ 2350 K have been reported [10]. Recent examples of hightemperature PAC studies of intermetallic compounds include the investigation of tracer diffusion [11], of solute site preference [12] and solute EFG's [13] up to temperatures T ∼ 1200 K.…”

Section: Introductionmentioning

confidence: 98%

Zirconium–indium intermetallic compounds investigated by measurements of nuclear electric quadrupole interactions

Saitovitch

Silva

Cavalcante

et al. 2010

Journal of Alloys and Compounds

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A furnace for high temperature perturbed angular correlation measurements

Cited by 15 publications

References 8 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

Electric field gradients in the rare earth–aluminium compoundsRAl2andRAl3studied by
Forker
¹
,
Presa
²

2007
Phys. Rev. B
Self Cite

Zirconium–indium intermetallic compounds investigated by measurements of nuclear electric quadrupole interactions

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A furnace for high temperature perturbed angular correlation measurements

Cited by 15 publications

References 8 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

Electric field gradients in the rare earth–aluminium compoundsRAl2andRAl3studied byForker1, Presa2 2007Phys. Rev. BSelf Cite

Zirconium–indium intermetallic compounds investigated by measurements of nuclear electric quadrupole interactions

Contact Info

Product

Resources

About

Electric field gradients in the rare earth–aluminium compoundsRAl2andRAl3studied by
Forker
¹
,
Presa
²

2007
Phys. Rev. B
Self Cite