On the effect of oxygen partial pressure on the chromium distribution coefficient in melt-grown ruby crystals

Ganschow, Steffen; Klimm, D.; Bertram, R.

doi:10.1016/j.jcrysgro.2011.04.033

Cited by 13 publications

(9 citation statements)

References 27 publications

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“…O a   , titanium will exist mainly in the 3 + state. It has been shown [16] that when pulling ruby (Cr 3+ :Al2O3) crystals the overall distribution of chromium can be controlled via the relative amounts of different chromium species, in that case Cr 2+ and Cr 3+ .…”

Section: Log( )mentioning

confidence: 99%

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Aluminium self-diffusion in high-purity α-Al2O3: Comparison of Ti-doped and undoped single crystals

et al. 2020

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Section: Log( )mentioning

confidence: 99%

“…2a). The matrix signals 16 O + , 18 O + and 27 Al ++ were also measured to detect any signal drift during the SIMS analysis. The magnesium peaks result from a small amount of magnesium in the 26 Al tracer solution [25].…”

Section: Diffusion Experimentsmentioning

confidence: 99%

Aluminium self-diffusion in high-purity α-Al2O3: Comparison of Ti-doped and undoped single crystals

et al. 2020

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“…The level of Cr 2 O 3 doping was unknown for our sample so a percentage weight of 0.05% was assumed, in accordance with typical literature values for such synthetically grown crystals. 43,44 For such a composition, the effective atomic number Z eff was calculated to be 11.40 (Ref. 45) and the relative electron density ρ e was calculated to be 3.51.…”

Section: C1 Experimental Detailsmentioning

confidence: 99%

Dose ratio proton radiography using the proximal side of the Bragg peak

et al. 2015

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Purpose: In recent years, there has been a movement toward single-detector proton radiography, due to its potential ease of implementation within the clinical environment. One such single-detector technique is the dose ratio method in which the dose maps from two pristine Bragg peaks are recorded beyond the patient. To date, this has only been investigated on the distal side of the lower energy Bragg peak, due to the sharp falloff. The authors investigate the limits and applicability of the dose ratio method on the proximal side of the lower energy Bragg peak, which has the potential to allow a much wider range of water-equivalent thicknesses (WET) to be imaged. Comparisons are made with the use of the distal side of the Bragg peak. Methods: Using the analytical approximation for the Bragg peak, the authors generated theoretical dose ratio curves for a range of energy pairs, and then determined how an uncertainty in the dose ratio would translate to a spread in the WET estimate. By defining this spread as the accuracy one could achieve in the WET estimate, the authors were able to generate lookup graphs of the range on the proximal side of the Bragg peak that one could reliably use. These were dependent on the energy pair, noise level in the dose ratio image and the required accuracy in the WET. Using these lookup graphs, the authors investigated the applicability of the technique for a range of patient treatment sites. The authors validated the theoretical approach with experimental measurements using a complementary metal oxide semiconductor active pixel sensor (CMOS APS), by imaging a small sapphire sphere in a high energy proton beam. Results: Provided the noise level in the dose ratio image was 1% or less, a larger spread of WETs could be imaged using the proximal side of the Bragg peak (max 5.31 cm) compared to the distal side (max 2.42 cm). In simulation, it was found that, for a pediatric brain, it is possible to use the technique to image a region with a square field equivalent size of 7.6 cm 2 , for a required accuracy in the WET of 3 mm and a 1% noise level in the dose ratio image. The technique showed limited applicability for other patient sites. The CMOS APS demonstrated a good accuracy, with a root-mean-square-error of 1.6 mm WET. The noise in the measured images was found to be σ = 1.2% (standard deviation) and theoretical predictions with a 1.96σ noise level showed good agreement with the measured errors. Conclusions: After validating the theoretical approach with measurements, the authors have shown that the use of the proximal side of the Bragg peak when performing dose ratio imaging is feasible, and allows for a wider dynamic range than when using the distal side. The dynamic range available increases as the demand on the accuracy of the WET decreases. The technique can only be applied to clinical sites with small maximum WETs such as for pediatric brains. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License...

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“…The main difficulty is the large difference of the ionic radii of the host cations of r(Al 3+ ) = 0.53 Å in the sixfold‐coordinated C 3v ‐site in the R

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c symmetry lattice of sapphire and the radius of the doping ion of r(Nd 3+ ) = 0.98 Å . In contrast, the ionic radius of Cr 3+ of 0.62 Å enables the growth of Cr 3+ :α‐Al 2 O 3 with segregation coefficients of about 1, allowing for the growth of large crystals with homogeneous doping concentration from the melt . However, already for Ti 3+ with an ionic radius of 0.67 Å the segregation coefficient is reduced to 0.1, imposing severe difficulties on the growth of large Ti:sapphire crystals with high optical quality .…”

Section: Introductionmentioning

confidence: 99%

Lasing of Nd³⁺ in sapphire

Waeselmann

Heinrich

Kränkel

et al. 2016

Laser & Photonics Reviews

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We present a rare‐earth‐doped sapphire laser. Single‐crystalline α‐Al2O3 films doped with trivalent neodymium have been grown by pulsed laser deposition on undoped sapphire substrates. The Nd3+ doping concentrations of the films have been varied between 0.3 at.% and 2 at.%. Epitaxial growth was proven by structural and optical characterization of the films. The samples exhibit strongly polarization dependent emission transitions from the 4F3/2 manifold with a fluorescence lifetime of 108 μs and peak emission cross sections of 1.1 × 10−18 cm2 around 1100 nm. Lasing at 1096.5 nm was achieved under Ti:sapphire‐pumping in a planar waveguide configuration with a maximum cw output power of 137 mW and a slope efficiency of 7.5% with respect to the incident pump power.

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On the effect of oxygen partial pressure on the chromium distribution coefficient in melt-grown ruby crystals

Cited by 13 publications

References 27 publications

Aluminium self-diffusion in high-purity α-Al2O3: Comparison of Ti-doped and undoped single crystals

Aluminium self-diffusion in high-purity α-Al2O3: Comparison of Ti-doped and undoped single crystals

Dose ratio proton radiography using the proximal side of the Bragg peak

Lasing of Nd³⁺ in sapphire

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On the effect of oxygen partial pressure on the chromium distribution coefficient in melt-grown ruby crystals

Cited by 13 publications

References 27 publications

Aluminium self-diffusion in high-purity α-Al2O3: Comparison of Ti-doped and undoped single crystals

Aluminium self-diffusion in high-purity α-Al2O3: Comparison of Ti-doped and undoped single crystals

Dose ratio proton radiography using the proximal side of the Bragg peak

Lasing of Nd3+ in sapphire

Contact Info

Product

Resources

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Lasing of Nd³⁺ in sapphire