Synthesis and characterization of HPHT large single-crystal diamonds under the simultaneous influence of oxygen and hydrogen

Fang, Chao; Zhang, Yuewen; Shen, Weixia; Sun, Shishuai; Zhang, Zhuangfei; Xue, Lisha; Jia, Xiaopeng

doi:10.1039/c7ce01349c

Cited by 29 publications

(18 citation statements)

References 39 publications

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“…In the HPHT process temperatures over 1300°C and pressures of several GPa are reached inside the reaction chamber to access the region of phase space where, from a diamond seed, using a source of carbon atoms the diamond crystal could grow [37]. In dosimetry, the crystal impurity content, which strongly depends on the fabrication process' optimization, is a relevant parameter for substrate performances [38].…”

Section: Diamond Fabricationmentioning

confidence: 99%

Diamond Detectors for Radiotherapy X-Ray Small Beam Dosimetry

et al. 2021

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Many new X-Ray treatment machines using small and/or non-standard radiation fields, e.g., Tomotherapy, Cyber-knife, and linear accelerators equipped with high-resolution multi-leaf collimators and on-board imaging system, have been introduced in the radiotherapy clinical routine within the last few years. The introduction of these new treatment modalities has led to the development of high conformal radiotherapy treatment techniques like Intensity Modulated photon Radiation Therapy, Volumetric Modulated Arc Therapy, and stereotactic radiotherapy. When using these treatment techniques, patients are exposed to non-uniform radiation fields, high dose gradients, time and space variation of dose rates, and beam energy spectrum. This makes reaching the required degree of accuracy in clinical dosimetry even more demanding. Continuing to use standard field procedures and detectors in fields smaller than 3 × 3 cm2, will generate a reduced accuracy of clinical dosimetry, running the risk to overshadowing the progress made so far in radiotherapy applications. These dosimetric issues represent a new challenge for medical physicists. To choose the most appropriate detector for small field dosimetry, different features must be considered. Short- and long-term stability, linear response to the absorbed dose and dose rate, no energy and angular dependence, are all needed but not sufficient. The two most sought-after attributes for small field dosimetry are water equivalence and small highly sensitive (high sensitivity) volumes. Both these requirements aim at minimizing perturbations of charged particle fluence approaching the Charged Particle Equilibrium condition as much as possible, while maintaining high spatial resolution by reducing the averaging effect for non-uniform radiation fields. A compromise between different features is necessary because no dosimeter currently fulfills all requirements, but diamond properties seem promising and could lead to a marked improvement. Diamonds have long been used as materials for dosimeters, but natural diamonds were only first used for medical applications in the 80 s. The availability of reproducible synthetic diamonds at a lower cost compared to natural ones made the diffusion of diamonds in dosimetry possible. This paper aims to review the use of synthetic poly and single-crystal diamond dosimeters in radiotherapy, focusing on their performance under MegaVoltage photon beams. Both commercial and prototype diamond dosimeters behaviour are described and analyzed. Moreover, this paper will report the main related results in literature, considering diamond development issues like growth modalities, electrical contacts, packaging, readout electronics, and how do they affect all the dosimetric parameters of interest such as signal linearity, energy dependence, dose-rate dependence, reproducibility, rise and decay times.

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Section: Diamond Fabricationmentioning

confidence: 99%

Diamond Detectors for Radiotherapy X-Ray Small Beam Dosimetry

et al. 2021

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“…Низкое содержание азота в наших образцах ДНА -на уровне фонового содержания -может быть объяснено тем, что нанопорошок ДНА марки УДА-С-ГО после химической очистки был подвергнут глубокой доочистке с использованием ионообменных и мембранных технологий, в результате которой, видимо, атомы азота, входящие в состав сорбированных молекул и функциональных групп, практически удалены с наночастиц. В образце частиц нанопорошка ПНА дополнительно зарегистрированы слабые линии от металлических примесей: вольфрама (W4 f ) и хлора (Cl2p [6,9,[11][12][13]. Значения энергий связи пиков, равные 284.1 ± 0.1 eV, характерны для атомов углерода в состоянии s p 2 -гибридизации (как в графите или фуллеренах) [6,9,[11][12][13].…”

Section: результаты и их обсуждениеunclassified

“…В образце частиц нанопорошка ПНА дополнительно зарегистрированы слабые линии от металлических примесей: вольфрама (W4 f ) и хлора (Cl2p [6,9,[11][12][13]. Значения энергий связи пиков, равные 284.1 ± 0.1 eV, характерны для атомов углерода в состоянии s p 2 -гибридизации (как в графите или фуллеренах) [6,9,[11][12][13]. Пики с энергиями связи 286.6 eV соответствуют атомам углерода в составе гидроксильных и эфирных групп (C−OH, C−O−C) [11][12][13].…”

Section: результаты и их обсуждениеunclassified

“…Значения энергий связи пиков, равные 284.1 ± 0.1 eV, характерны для атомов углерода в состоянии s p 2 -гибридизации (как в графите или фуллеренах) [6,9,[11][12][13]. Пики с энергиями связи 286.6 eV соответствуют атомам углерода в составе гидроксильных и эфирных групп (C−OH, C−O−C) [11][12][13]. Наименее интенсивные пики с энергиями связи 287.9 ± 0.3 eV характеризуют состояние атомов углерода в составе карбоксильных групп (O=C−O, COOH).…”

Section: результаты и их обсуждениеunclassified

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Рентгеновская Фотоэлектронная Спектроскопия Наноалмазов, Полученных Измельчением И Детонационным Синтезом

Sharin¹,

Сивцева²,

Попов³

2021

Журнал Технической Физики

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The chemical composition and surface state of nanopowder particles prepared by milling natural diamond and detonation synthesis were studied by the method of X-ray photoelectron spectroscopy. It has been shown that the primary particles of both nanopowders contain mainly carbon and oxygen atoms. The signals in the photoelectronic spectrum from atoms of nitrogen, sulfur, chlorine and metals do not exceed the noise level. It was found that in primary particles of detonation synthesis nanodiamond and nanopowder obtained by grinding natural diamond, the proportions of carbon atoms in the sp3 hybridization state are ~ 46.5 and ~ 67.8%, sp2 hybridization is ~ 26.8 and ~ 17.4% and in the composition of oxygen-containing functional groups ~ 26.7 and ~ 14.7%, respectively.

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“…24 In addition, the surface termination of NDs cannot be defined simply as it can be for bulk diamonds, where X-ray photo-emission spectroscopy (XPS) determines even the surface coverage ratio of various oxygen terminals such as ester, carbonyl, and carboxyl. 31,32 This surface inhomogeneity must be quantitatively understood to extend T 2 in NDs. Statistical approaches examining the number of ND particles are required for obtaining the clear surface-T 2 relation undermined by surface inhomogeneity.…”

Section: Introductionmentioning

confidence: 99%

Effect of surface oxidation on electron spin coherence of single nitrogen-vacancy centers in nanodiamonds

Tsukahara,

Fujiwara,

Sera

et al. 2018

Preprint

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Fluorescent nanodiamonds (NDs) are crystaldefect-based light-emitting nanoparticles that can be applied to quantum information science and quantum sensing. Of particular interest are nitrogen vacancy (NV) centers that allow optical access to their coherently controllable electron spin systems, leading to spin-photon quantum devices and nanoscale sensing of various physical parameters. However, the NV spin coherence time (T 2 ) in NDs has been limited to one or two orders of magnitude shorter than those in bulk diamonds owing to the complicated surface effect that decoheres the NV spin systems. Here, we study the relation between the surface properties and T 2 of single NV centers in NDs by systematically analyzing the effect of surface oxidation. We apply aerobic and acidic oxidation methods with various heating temperatures and processing times and find that aerobic oxidation most effectively oxidizes the surface and extends T 2 by a factor of 1.6 to the original NDs. The ND-size dependence of T 2 clearly shows that the surface oxidation removes a constant decoherence contribution irrespective of the ND size and that a new surface-derived decoherence source emerges when the ND size reduces below 50 nm. The present results provide quantitative information on the decoherence sources of NV spin systems of NDs and will enable a strategic surface modification for better spin manipulations of NV centers in the context of quantum information science and nanoscale quantum sensing.

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Synthesis and characterization of HPHT large single-crystal diamonds under the simultaneous influence of oxygen and hydrogen

Abstract: In this paper, we report the influence of oxygen and hydrogen additives in the metal melt on the growth process, morphology, and defect-and-impurity structure of large single-crystal diamonds.

Cited by 29 publications

References 39 publications

Diamond Detectors for Radiotherapy X-Ray Small Beam Dosimetry

Diamond Detectors for Radiotherapy X-Ray Small Beam Dosimetry

Рентгеновская Фотоэлектронная Спектроскопия Наноалмазов, Полученных Измельчением И Детонационным Синтезом

Effect of surface oxidation on electron spin coherence of single nitrogen-vacancy centers in nanodiamonds

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