LPHT annealing of brown-to-yellow type Ia diamonds

Eaton-Magaña, Sally; Ardon, Troy; Зайцев, А.М.

doi:10.1016/j.diamond.2017.06.008

Cited by 20 publications

(14 citation statements)

References 36 publications

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“…HPHT treatment at 2000 to 2250 • C performed on selected type I DR diamonds has shown that all AC absorptions described in this chapter are annealed out under such conditions; the effective annealing temperature is somewhere between 1850 and 2000 • C, which is consistent with the earlier published values [22]. A summary of the various ACs, their annealing behavior and their possible interpretations can be found in Table 3.…”

Section: The Annealing Behavior Of the Amber Centers And Naturally Ocsupporting

confidence: 87%

“…These results show that the 4063 cm −1 AC is clearly the least stable of all the ACs since it is affected by heating as low as 1150 • C-distinctly lower than the value of 1700 • C published earlier [22]-and that the 4167 cm −1 and the 4111 cm −1 ACs are the most stable of all the ACs as they remain essentially unaffected by heating to 1850 • C, except for likely some charge-related modifications occurring for the 4111 cm −1 AC. Since annealing out the 4063 cm −1 AC results in a distinct increase or formation of the 4167 cm −1 AC and when the 4111 cm −1 AC is present also in an increase in the 4111 cm −1 AC and the associated 4136 cm −1 AC; it seems reasonable to suggest that the 4167 cm −1 and 4111 cm −1 AC form out of the 4063 cm −1 AC, hence the 4063 cm −1 AC appears to be a precursor of the those ACs.…”

Section: The Annealing Behavior Of the Amber Centers And Naturally Occontrasting

confidence: 57%

“…While all ACs and natural H1b in brown diamonds have been shown to anneal out by HPHT treatment from about 2000 • C [19], limited and incomplete data on the annealing behavior of the ACs at a lower temperature is available [22], while no data on the behavior of natural H1b at a lower temperature have been published, and no data whatsoever on the annealing behavior of natural H1c have been published so far. Therefore, some samples with IR spectra representing the different ACs and samples with H1b and H1c were annealed up to 1500 • C in this study, and some were treated by HPHT at 1850 • C up to 2250 • C.…”

Section: The Annealing Behavior Of the Amber Centers And Naturally Ocmentioning

confidence: 99%

“…While the annealing behavior of most PL defects of DR brown diamonds by temperatures used during the HPHT treatment (2000-2500 • C) are relatively well known, their behavior at lower temperatures are not well studied and only some data on LPHT (low pressure, high temperature) treatments has been published for type Ia diamonds [22]. Therefore, annealing experiments up to 1500 • C were performed to check the stability of the PL defects in DR type I brown diamonds.…”

Section: The Behavior Of Pl Defects Upon Annealingmentioning

confidence: 99%

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A Defect Study and Classification of Brown Diamonds with Deformation-Related Color

Hainschwang

Notari²,

Pamies

2020

Minerals

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For this study, the properties of a large sample of various types of brown diamonds with a deformation-related (referred to as “DR” in this work) color were studied to properly characterize and classify such diamonds, and to compare them to pink to purple to red diamonds. The acquisition of low temperature NIR spectra for a large range of brown diamonds and photoexcitation studies combined with various treatment experiments have opened new windows into certain defect characteristics of brown diamonds, such as the amber centers and naturally occurring H1b and H1c centers. It was determined that the amber centers (referred to as “AC” in this work) exhibit rather variable behaviors to annealing and photoexcitation; the annealing temperature of these defects were determined to range from 1150 to >1850 °C and it was found that the 4063 cm−1 AC was the precursor defect of many other ACs. It is suggested that the amber centers in diamonds that contain at least some C centers are essentially identical to the ones seen in diamonds without C centers, but that they likely have a negative charge. The study of the naturally occurring H1b and H1c link them to the amber centers, specifically to the one at 4063 cm−1. Annealing experiments have shown that the H1b and H1c defects and the 4063 cm−1 AC were in line with each other. The obvious links between these defects points towards our suggestion that the H1b and H1c defects are standalone defects that consist of multiple vacancies and nitrogen and that they are—in the case of brown diamonds—a side product of the AC formation. A new classification of DR brown diamonds was elaborated that separates the diamonds in six different classes, depending on type and AC. This classification had been completed recently with the classification of brown diamonds with a non-deformation-related color (referred to as “NDR”), giving a total of 11 classes of brown diamonds.

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Section: The Annealing Behavior Of the Amber Centers And Naturally Ocsupporting

confidence: 87%

Section: The Annealing Behavior Of the Amber Centers And Naturally Occontrasting

confidence: 57%

Section: The Annealing Behavior Of the Amber Centers And Naturally Ocmentioning

confidence: 99%

Section: The Behavior Of Pl Defects Upon Annealingmentioning

confidence: 99%

See 2 more Smart Citations

A Defect Study and Classification of Brown Diamonds with Deformation-Related Color

Hainschwang

Notari²,

Pamies

2020

Minerals

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“…During this course, the newly formed H1a and H1b centers could have been partially annealed out and contributed to the growth of the H2 center (Collins et al, 2005). Taking into account the temperature stability of the H1a and H1b centers, we speculate that the annealing at this temperature was performed for a relatively short time to allow a partial survival of the H1a and H1b centers (prolonged heating at temperatures over 1400°C is needed to completely eliminate H1a or H1b absorption; e.g., Woods, 1984;Collins et al, 2005;Eaton-Magaña et al, 2017;Zaitsev et al, 2018) and the H4 center (Woods and Collins, 1986;Buerki et al, 1999). Besides, type Ia diamonds colored by strong H3 and H2 centers that were produced via irradiation and subsequent prolonged annealing at 1400°C may have an unappealing appearance (a drab, unattractive green color) (Woods and Collins, 1986).…”

Section: Possible Treatment Processmentioning

confidence: 99%

Hydrogen-Rich Green Diamond Color-Treated by Multi-Step Processing

Huang¹,

Ni²,

Shui³

et al. 2019

G&G

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A cut diamond of intense yellowish green color has been characterized using microscopy and spectroscopic techniques. The diamond has been unambiguously identified as color-treated. The simultaneous presence of multiple centers related to irradiation and annealing-including H1a, H1b, NV 0 , NV-, H3, H4, GR1, and H2-was revealed. UV-Vis-NIR absorption spectroscopy showed that the diamond owes its color to the two major bands related to H3 and GR1. The combination of these spectroscopic features in one diamond has not been reported in the gemological literature, suggesting that this diamond was subjected to a complex treatment procedure that is not frequently applied. Taking into account the thermal stability of the defects involved and the defect transformations at high temperatures, two possible treatment procedures explaining the observed combination of spectroscopic features are proposed.

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Enhanced Optical ¹³C Hyperpolarization in Diamond Treated by High‐Temperature Rapid Thermal Annealing

et al. 2020

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Methods of optical dynamic nuclear polarization open the door to the replenishable hyperpolarization of nuclear spins, boosting their nuclear magnetic resonance/imaging signatures by orders of magnitude. Nanodiamond powder rich in negatively charged nitrogen vacancy defect centers has recently emerged as one such promising platform, wherein 13C nuclei can be hyperpolarized through the optically pumped defects completely at room temperature. Given the compelling possibility of relaying this 13C polarization to nuclei in external liquids, there is an urgent need for the engineered production of highly “hyperpolarizable” diamond particles. Here, a systematic study of various material dimensions affecting optical 13C hyperpolarization in diamond particles is reported on. It is discovered surprisingly that diamond annealing at elevated temperatures ∼1720 °C has remarkable effects on the hyperpolarization levels enhancing them by above an order of magnitude over materials annealed through conventional means. It is demonstrated these gains arise from a simultaneous improvement in NV− electron relaxation/coherence times, as well as the reduction of paramagnetic content, and an increase in 13C relaxation lifetimes. This work suggests methods for the guided materials production of fluorescent, 13C hyperpolarized, nanodiamonds and pathways for their use as multimodal (optical and magnetic resonance) imaging and hyperpolarization agents.

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LPHT annealing of brown-to-yellow type Ia diamonds

Cited by 20 publications

References 36 publications

A Defect Study and Classification of Brown Diamonds with Deformation-Related Color

A Defect Study and Classification of Brown Diamonds with Deformation-Related Color

Hydrogen-Rich Green Diamond Color-Treated by Multi-Step Processing

Enhanced Optical ¹³C Hyperpolarization in Diamond Treated by High‐Temperature Rapid Thermal Annealing

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LPHT annealing of brown-to-yellow type Ia diamonds

Cited by 20 publications

References 36 publications

A Defect Study and Classification of Brown Diamonds with Deformation-Related Color

A Defect Study and Classification of Brown Diamonds with Deformation-Related Color

Hydrogen-Rich Green Diamond Color-Treated by Multi-Step Processing

Enhanced Optical 13C Hyperpolarization in Diamond Treated by High‐Temperature Rapid Thermal Annealing

Contact Info

Product

Resources

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Enhanced Optical ¹³C Hyperpolarization in Diamond Treated by High‐Temperature Rapid Thermal Annealing