Growth and characterization of graphite single crystals

Austerman, S.B.; Myron, S.M.; Wagner, J.

doi:10.1016/0008-6223(67)90032-2

Cited by 43 publications

(13 citation statements)

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“…Some etch pits 17 in Fig: 3d are flat bottomed. Such etch pits reveal either clusters of impurities (or of point defects) in the walls [- [54][55][56][57][58][59] or forest dislocations changing in basal plane dislocations [60][61][62][63].…”

Section: 2 Straight Dislocationsmentioning

confidence: 99%

“…There is no clear evidence as to whether the characteristic stepped shape of the etch pits on basal planes in different layered structures [58,59,82] is the result of the dissolution kinetics (involving dissolution inhibition by adsorption of impurities at kinks in surface steps followed by step bunching, as in other non-layered structures [54,65,66,83]) or if it actually reveals inhomogeneously distributed basal plane two-dimensional faults as: stacking faults, glide bands, intercalated impurity layers, or hohlstellen (microcleavages or delaminations).…”

Section: 2 Straight Dislocationsmentioning

confidence: 99%

“…A lot of quadratic flat bottomed etch pits of different size and shape as seen in Figs 4c and d reveal clusters of impurities or of point defects [54,59,[84][85][86]. Alternatively, they may reveal small dislocation jogs crossing the basal planes [12, 20, 56, 60-63] or forest dislocations ending inside the crystal at microcleavages [48].…”

Section: 2 Straight Dislocationsmentioning

confidence: 99%

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Extended structural defects in ?-Hgl2 single crystals

Nicolau

Dupuy

Rolland

1993

J Mater Sci: Mater Electron

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Extended structural defects in both ~-Hgl 2 crystals grown in solution or from the vapourphase were studied by optical microscopy, light scattering, SEM operated in cathodoluminescence and in secondary electron mode, X-ray topography, neutron, y-and X-ray rocking curves and oscillating crystal X-ray diffraction. The observed dislocations were compared with theoretically calculated dislocations. Dislocation loops, having diameters ranging from 2 gm to 500 gm, are observed on all low index faces, Hohlstellen (lens-shaped voids) having axes along the [001] direction, less than 1 gm in thickness, and diameters lying in the (001) planes, ranging from 2 gm to 10 gm are characteristic defects. Observed plastic deformations like glide sheets and bands, tilt and twist boundaries, kink and fatigue bands, ridges and rumplings were characterized. Growth rings, spherical void inclusions 10-30 gm in diameter, orthogonal walls of forest screw dislocations parallel to {1 00} planes, and streaks (planar void sheets crossing the (001 ) planes) were only observed in crystals grown from the vapour-phase. Cross-penetration twins having {1 1 4} twin planes are described. The possible formation of stacking faults was analysed. The mosaicity of solution-grown crystals ranges from 1' to 6'. A characteristic cellular structure, having a cell size ranging from 2 I~m to 10 gm, was observed in all the crystals examined and correlated to local deviations from the stoichiometric composition. Solid lens-shaped inclusions, having diameters ranging from 3 gm to 500 gm and thicknesses ranging from 0.3 gm to 50 gm, respectively, are entrapped in many crystals and correlated to spiral hillocks observed on {0 01 } growing faces.

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Section: 2 Straight Dislocationsmentioning

confidence: 99%

Section: 2 Straight Dislocationsmentioning

confidence: 99%

Section: 2 Straight Dislocationsmentioning

confidence: 99%

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Extended structural defects in ?-Hgl2 single crystals

Nicolau

Dupuy

Rolland

1993

J Mater Sci: Mater Electron

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“…In this paper, some recent observations are reported and discussed. Use of the classification proposed by Austerman et al [1] will be made, according to which twist disorder denotes cases where basal planes are rotated while remaining parallel and tilt disorder is for cases when basal planes do not remain parallel to one another.…”

Section: Introductionmentioning

confidence: 99%

Misorientations in spheroidal graphite: some new insights about spheroidal graphite growth in cast irons

Lacaze

Theuwissen

Laffont

et al. 2016

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. Local diffraction patterning, orientation mapping and high resolution transmission electron microscopy imaging have been used to characterize misorientations in graphite spheroids of cast irons. Emphasis is put here on bulk graphite, away from the nucleus as well as from the outer surface of the spheroids in order to get information on their growth during solidification. The results show that spheroidal graphite consists in conical sectors made of elementary blocks piled up on each other. These blocks are elongated along the prismatic a direction of graphite with the c axes roughly parallel to the radius of the spheroids. This implies that the orientation of the blocks rotates around the spheroid centre giving low angle tilting misorientations along tangential direction within each sector. Misorientations between neighbouring sectors are of higher values and their interfaces show rippled layers which are characteristic of defects in graphene. Along a radius of the spheroid, clockwise and anticlockwise twisting between blocks is observed. These observations help challenging some of the models proposed to explain spheroidal growth in cast ions.

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“…Recently, new applications have been envisioned for hBN that take advantage of its unique structural, optical and electronic properties. These include nanophotonics [5] exploiting its highly anisotropic optical properties, two dimensional atomically-thin transistors that employ hBN's ultra-smooth surfaces, high resistivity, and lattice matching with graphene [6,7], deep ultraviolet emission, made possible by hBN's large energy band gap (5.8 eV) and high exciton binding energy [8,9], and solidstate neutron detectors, which rely on the strong interaction of thermal neutrons with the boron-10 isotope [10,11]. These applications require hBN of high structural perfection; defects such as dislocations create charge traps, scattering centers, and recombination sites that degrade its optical and charge transport properties (mobility and minority carrier lifetimes) [9,[12][13][14].…”

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confidence: 99%

Assessing Hexagonal Boron Nitride Crystal Quality by Defect Sensitive Etching

et al. 2017

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Hexagonal boron nitride (hBN), the graphite-like polymorph, has been employed for more than 55 years as powders, ceramics, amorphous films, and deposited fine-grain polycrystalline pyrolytic forms (pBN) in applications that take advantage of its high thermal stability, chemical inertness, high thermal conductivity, low x-ray absorption, high electrical resistivity, and lubricating properties [1][2][3][4]. Recently, new applications have been envisioned for hBN that take advantage of its unique structural, optical and electronic properties. These include nanophotonics [5] exploiting its highly anisotropic optical properties, two dimensional atomically-thin transistors that employ hBN's ultra-smooth surfaces, high resistivity, and lattice matching with graphene [6,7], deep ultraviolet emission, made possible by hBN's large energy band gap (5.8 eV) and high exciton binding energy [8,9], and solidstate neutron detectors, which rely on the strong interaction of thermal neutrons with the boron-10 isotope [10,11]. These applications require hBN of high structural perfection; defects such as dislocations create charge traps, scattering centers, and recombination sites that degrade its optical and charge transport properties (mobility and minority carrier lifetimes) [9, 12-14].Here we develop defect sensitive etching (DSE) to quantify the density of non-basal plane dislocations in hBN single crystals. Single crystals were precipitated from a molten nickel-chromium flux saturated with hBN at 1500 °C under 1 bar of flowing N2, followed by slow cooling (2-4 °C/hour). Etching the crystals in a molten eutectic mixture of NaOH and KOH between 450 °C and 525 °C for 1 minute produced hexagonal pits on (0001) planes. The morphology and topography of these pits were characterized using optical microscopy, SEM and AFM. All etch pits were oriented in the same direction within individual grains. Three types of hexagonal etch pits formed: pits with inclined side walls, flat-bottom pits, and pits combining these features. From an Arrhenius plot of the log of the etch rate versus the inverse temperature, an activation energy of 60 kJ/mol was estimated. Screw and mixed-type threading dislocations were also identified in the crystal bulk using diffraction-contrast transmission electron microscopy (TEM). This work demonstrates that DSE is an effective method for estimating the density of non-basal plane dislocations in hBN [15].

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Growth and characterization of graphite single crystals

Cited by 43 publications

References 13 publications

Extended structural defects in ?-Hgl2 single crystals

Extended structural defects in ?-Hgl2 single crystals

Misorientations in spheroidal graphite: some new insights about spheroidal graphite growth in cast irons

Assessing Hexagonal Boron Nitride Crystal Quality by Defect Sensitive Etching

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