Cyclic Twins of CVD Diamond Crystals

Kvasnytsya, V.M.; Kvasnytsia, I. V.

doi:10.3103/s1063457619060017

Cited by 8 publications

(5 citation statements)

References 13 publications

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“…Considering the narrow variation of tested temperatures, little changes on orientation of the films could be observed as consequence of this variation, based on observations of Wild et al 38,39 and others 40,41 , significant changes occur from the range of 700 to 1000 °C, also impacted by pressure and methane concentration but in a less critical manner.…”

Section: Morphology and Thicknessmentioning

confidence: 91%

Growth and Characterization of Polycrystalline CVD Diamond Films Obtained by MWPACVD at High Power 2,45GHz Microwave Discharge

et al. 2022

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Among all the allotropic forms of carbon, diamond has attracted a broad scientific and technological interest for its extreme and unique properties rarely matched by other materials in nature. In a rapid rise from a technological point of view, much has been achieved in the study of obtaining this material through CVD technique. Studies of CVD diamond growth parameters of monocrystalline structure, underway in the team, are very expensive and time-consuming requiring in-depth studies of CVD diamond growth parameters of polycrystalline structure. So, this work presents an analysis focused on obtaining CVD diamond films with polycrystalline structure through the 2.45 GHz microwave plasma activation method (MWPACVD) in high power regime using a modified substrate holder to find a set of parameters appropriated for getting uniform quality and growth rate of thick films. The films were characterized using Raman scattering spectroscopy and scanning electron microscopy. The results point to optimized conditions for depositing films with growth rates of up to 20 µm/h with low levels of intrinsic stress, good structural quality and uniform microcrystalline morphology along the deposition surface.

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Section: Morphology and Thicknessmentioning

confidence: 91%

Growth and Characterization of Polycrystalline CVD Diamond Films Obtained by MWPACVD at High Power 2,45GHz Microwave Discharge

et al. 2022

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“…Pseudopentagonal and icosahedral intergrowths of cyclic spinel twins of cuboctahedral microcrystals of CVD diamond were found at the microlevel [42][43][44]. They can also be the prototype for the formation of complex multiple twins in ballases.…”

Section: Crystallographic Model Of Crystals Multiple Twinning In Ballmentioning

confidence: 94%

Morphology and Genesis of Ballas and Ballas-Like Diamonds

et al. 2020

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Ballas diamond is a rare form of the polycrystalline radial aggregate of diamonds with diverse internal structures. The morphological features of ballas diamonds have experienced repeated revision. The need that this paper presents for development of a crystal-genetic classification was determined by a rich variety of combined and transitional forms of ballas-like diamonds, which include aggregates, crystals, and intergrowths. The new crystal-genetic classification combines already-known and new morphological types of ballas as well as ballas-like diamonds discovered in the placers of Yakutia, the Urals, and Brazil. The ballas-like diamond forms include spherocrystals, aggregates with a single crystal core, split crystals, radial multiple twin intergrowths, and globular crystals. The crystal genetic scheme of the evolution of ballas and ballas-like diamonds is a sequence of the morphological types arranged in accordance with the conventional model of the dependence of the mechanism and diamond growth from carbon supersaturation developed by I. Sunagawa. The evolution of the growth forms of ballas and ballas-like diamonds was tracked based on the macrozonal structure of diamonds varying from a flat-faced octahedron to a fibrous cuboid with its transition forms to the radiating crystal aggregates. The morphological diversity of the ballas-like diamonds depends on the level of supersaturation, and abrupt changes of the level of supersaturation engender abrupt changes in a mechanism of crystal growth. The change in the rate of growth under the influence of adsorption and absorption of the mechanic impurities accompanied the sudden appearance of the autodeformation defects in the form of splitting and multiple radial twinning of crystals. The spherical shape of Yakutia ballas-like diamonds is due to the volumetric dissolution that results in the curved-face crystals of the “Urals” or “Brazilian” type associated with ballas diamonds in placers.

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“…However, cyclic twins represent a different form of rotational symmetry seen in synthetic diamonds. These arise from cyclic twinning according to the spinnel law on the (111) plane 47 . Such a variety of cyclic twins is highly diverse and is characteristic of synthetic diamonds.…”

Section: Hr-tem and Electron Diffraction Studiesmentioning

confidence: 99%

“…Such a variety of cyclic twins is highly diverse and is characteristic of synthetic diamonds. Furthermore, it has been reported that the arrangement of cyclic twins in crystals can produce pseudo-pentagonal, icosahedral rotational symmetries, and other external morphologies in laboratory-grown diamonds 47 . An interesting feature of the dodecagonal symmetry is that the interface twin domains consist of five-and six-member rings as shown in Figure 7d.…”

Section: Hr-tem and Electron Diffraction Studiesmentioning

confidence: 99%

Diaphite: diamond-graphene hybrid nanostructures grown in CH4/H2/N2 chemistry

Sodisetti,

Bhattacharyya

2024

Preprint

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Here, we demonstrate the deposition of Diaphitic domains (diamond-graphene composite nanostructure) in a hydrogen (H2)-rich plasma gas chemistry. The distinct structural characteristics formed within ultra-nanocrystalline diamond (UNCD) films, with varying nitrogen (N2) concentrations in the gas mixture from 5% to 20%, were examined using a combination of electron microscopy and diffraction methods. Atomic force microscopy (AFM) and X-ray diffraction (XRD) measurements indicated the formation of an average diamond grain size of ∼ 5 nm. High-resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) revealed the presence of five-fold, six-fold and twelve-fold symmetry features, along with a forbidden {200} crystallographic reflection associated with the Diaphite structure in the UNCD films. These hybrid features, which combine elements of both diamond and graphene, were observed in both 5% and 10% N2-doped UNCD films and are the result of the interface between sp3 and sp2 domains, where sp3 grains are covalently bonded with sp2 grains.The emergence of these unconventional features in artificially grown diamonds is linked to nitrogen doping and secondary nucleation initiated by H2, leading to non-equilibrium growth conditions that potentially induce polymorphism in the diamond.Our discoveries offer insights into the creation of structural defects that are correlated with N2 doping in a plasma mixture of CH4/H2, thus enabling the development of novel nanodiamond structures through regulated doping.

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Cyclic Twins of CVD Diamond Crystals

Cited by 8 publications

References 13 publications

Growth and Characterization of Polycrystalline CVD Diamond Films Obtained by MWPACVD at High Power 2,45GHz Microwave Discharge

Growth and Characterization of Polycrystalline CVD Diamond Films Obtained by MWPACVD at High Power 2,45GHz Microwave Discharge

Morphology and Genesis of Ballas and Ballas-Like Diamonds

Diaphite: diamond-graphene hybrid nanostructures grown in CH4/H2/N2 chemistry

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