Crystal Pulling from the Melt

Hurle, D.T.J.

doi:10.1007/978-3-642-78208-4

Cited by 64 publications

(50 citation statements)

References 139 publications

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“…In this technique the crystal grows from the melt by solidification of the surface of a crystalline seed, which is dipped into the melt and subsequently slowly pulled away from it. 9 In this case the composition of the icosahedral crystal is different from that of the initial alloy due to the peritectic character of i-Al-Pd-Mn formation. 10 Coarsely speaking, for a successful growth the alloy composition should contain about two atomic percent 11 Since the crystal thus contains less Al and more Mn than the initial alloy, the Al concentration should increase and that of Mn should decrease during the crystal growth.…”

Section: Methodsmentioning

confidence: 99%

Isotropic magnetoresistance of icosahedral Al-Pd-Mn

et al. 1999

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The temperature dependence of the electrical resistivity (T) and the magnetoresistance ⌬(B,T)/(0,T) have been studied along the twofold and fivefold symmetry directions of an icosahedral Al-Pd-Mn in a high quality monograin crystal. To control the influence of any magnetic contribution, samples from the transversal and axial extremes of the crystal were measured along both the twofold and fivefold symmetry directions. The temperature dependence of the resistivity and the magnetoresistance were found to be isotropic. (T) and ⌬(B,T)/(0,T) varied in a random way in the transversal direction of the ingot, while systematic variations were observed along the growth direction. These observations could be qualitatively correlated to a gradient of the Mn concentration of below 0.2%/cm in the growth direction of the crystal.

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Section: Methodsmentioning

confidence: 99%

Isotropic magnetoresistance of icosahedral Al-Pd-Mn

et al. 1999

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“…Nanometre sized defects in Si can be caused by the aggregation of Si interstitials into more complex defects [33,34], or due to the entrapment of nanosized crystals forming pockets at the growth front. In the unmodified alloy, Si grows ahead of the solidifying front by the TPRE mechanism [24].…”

Section: Al and Sr Concentrations In Simentioning

confidence: 99%

“…Given this anisotropic growth mode and due to the low solubility and low distribution coefficient of Al in Si (k=0.002) [35], Al will be accumulated at the growth front. At a certain Al concentration, entrapment of this Al-rich layer in small pockets of high Al concentration can occur [34,36]. Moreover, Si clusters which were not completely dissolved in the melt can also be incorporated at the solidifying growth front resulting in interstitial lattice defects [37].…”

Section: Al and Sr Concentrations In Simentioning

confidence: 99%

Comparison of segregations formed in unmodified and Sr-modified Al–Si alloys studied by atom probe tomography and transmission electron microscopy

Barrirero

Engstler

Ghafoor

et al. 2014

Journal of Alloys and Compounds

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Comparison of segregations formed in unmodified and Sr-modified Al-Si alloys studied by atom probe tomography and transmission electron microscopy, 2014, Journal of Alloys and Compounds, (611) AbstractThe mechanical properties of Al-7 wt.% Si can be enhanced by structural modifications of its eutectic phase. Addition of low concentrations of certain elements, in this case 150 wt-ppm Sr, is enough to cause a transition from a coarse plate-like Si structure to a finer coralline one. To fully understand the operating mechanism of this modification, the composition of the eutectic Si phase in unmodified and Sr-modified alloys was analysed and compared by Atom Probe Tomography and (Scanning) Transmission Electron Microscopy. The unmodified alloy showed nanometre sized Al-segregations decorating defects, while the Sr-modified sample presented three types of Al-Sr segregations: (1) rod-like segregations that promote smoothening of the Al-Si boundaries in the eutectic phase, (2) particle-like segregations comparable to the ones seen in the unmodified alloy, and (3) planar segregations favouring the formation of twin boundaries. Al and Sr solubilities in Si after solidification were determined to be 430 ± 160 at-ppm and 40 ± 10 at-ppm, respectively. Sr predominantly segregates to the Si phase confirming its importance in the modification of the eutectic growth.

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“…(b) The dopant concentration (along the growth axis) at the distance z from the origin of the crystal can be obtained by using the classical relation [15]:…”

Section: Determination Of the Effective Segregation Coefficient Of Pbmentioning

confidence: 99%

Distribution of Pb²⁺Ions in PbF₂-Doped CaF₂Crystals

et al. 2010

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Calcium fluoride crystals doped with various concentrations of PbF 2 have been grown using the Bridgman technique. The optical absorption spectra reveal the characteristic UV absorption bands of the Pb 2+ ions. The distribution of the Pb 2+ -ions along four crystals has been investigated using the optical absorption method. Taking into account the relationship between the optical absorption coefficient and the concentration of the impurities in the samples, the effective segregation coefficient of the Pb 2+ ions has been calculated. Our study shows that the effective segregation coefficient of the Pb 2+ ions in CaF 2 host depends on the dopant concentration, and varies between 0.85 and 1.15, for 0.5 mol%PbF 2 and 3 mol%PbF 2 -doped CaF 2 , respectively.

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Crystal Pulling from the Melt

Cited by 64 publications

References 139 publications

Isotropic magnetoresistance of icosahedral Al-Pd-Mn

Isotropic magnetoresistance of icosahedral Al-Pd-Mn

Comparison of segregations formed in unmodified and Sr-modified Al–Si alloys studied by atom probe tomography and transmission electron microscopy

Distribution of Pb²⁺Ions in PbF₂-Doped CaF₂Crystals

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Crystal Pulling from the Melt

Cited by 64 publications

References 139 publications

Isotropic magnetoresistance of icosahedral Al-Pd-Mn

Isotropic magnetoresistance of icosahedral Al-Pd-Mn

Comparison of segregations formed in unmodified and Sr-modified Al–Si alloys studied by atom probe tomography and transmission electron microscopy

Distribution of Pb2+Ions in PbF2-Doped CaF2Crystals

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Distribution of Pb²⁺Ions in PbF₂-Doped CaF₂Crystals