Diamond & Related Materials 17 (2008) 1179–1185
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Diamond & Related Materials j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / d i a m o n d
Extraterrestrial, terrestrial and laboratory diamonds — Differences and similarities A. Karczemska a,b,⁎, M. Szurgot c, M. Kozanecki d, M.I. Szynkowska e, V. Ralchenko a,f, V.V. Danilenko a, P. Louda a,g, S. Mitura a,g,h a
Centre of Excellence NANODIAM, Poland Institute of Turbomachinery, Technical University of Lodz, Poland Center of Mathematics and Physics, Technical University of Lodz, Poland d Department of Molecular Physics, Technical University of Lodz, Poland e Institute of General and Ecological Chemistry, Technical University of Lodz, Poland f General Physics Institute, Moscow, Russia g Technical University of Liberec, Czech Republic h Institute of Materials Science and Engineering, Technical University of Lodz, Poland b c
a r t i c l e
i n f o
Available online 23 February 2008 Keywords: Diamond Lonsdaleite Nanodiamond NCD UDD PA CVD Meteorite
a b s t r a c t Characterization tools such as confocal Raman micro-spectroscopy, Laser Ablation (LA-ICP-TOF-MS) and SEMEDS were used to characterize meteorites: primitive achondrite — not classified NWA XXX ureilite found in 2006 in Morocco and the graphite nodula from the Canyon Diablo iron meteorite. The presence of diamond was confirmed in both samples. There are two kinds of meteoritic diamonds: diamonds of the sizes of microns up to millimeters are most probably of impact origin, nanodiamonds of the sizes of 1–3 nm, called presolar diamonds because of the isotopic anomalies, are believed to be formed before our Solar System was formed. There are many theories concerning presolar diamonds formation, among them: impact shock metamorphism driven by supernovae or chemical vapor deposition (CVD) from stellar outflows. We examined the properties of diamond nanopowders obtained by the PA CVD and detonation methods. Nanodiamonds obtained by the detonation method, called ultradispersed detonation diamonds (UDD), are of the same range of sizes as presolar diamonds. The results show both differences and similarities among meteoritic, terrestrial and laboratory diamonds. The comparison will help to understand the processes during presolar nanodiamonds formation. © 2008 Elsevier B.V. All rights reserved.
1. Introduction A comparison of extraterrestrial, terrestrial and laboratory diamonds (synthesized under known conditions) give scientists new possibilities to understand diamond growth processes [1,2]. Extraterrestrial diamonds have the different origins. Especially interesting are meteoritic nanodiamonds believed to be presolar because of the isotopic anomalies they contain. They are of the sizes of 1–3 nm and they are the most abundant of pesolar grains found in meteorites. They are described in detail elsewhere [1–5]. Diamonds are found in different kinds of meteorites [6]: in those which show large amount of alteration such as ureilities and achondrites, meteorites which appear quite analtered such as chondrites, metal-rich meteorites. Diamond exists in several polytypes [6], it means crystalline forms, that exhibit cubic, hexagonal or rombohedral symmetry. “Most
⁎ Corresponding author. Institute of Turbomachinery, Technical University of Lodz, Poland. E-mail address:
[email protected] (A. Karczemska). 0925-9635/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.diamond.2008.02.021
terrestrial diamond is cubic while that found in meteorites may have any of the three forms above. There is only one form of cubic diamond but there are several hexagonal, and rhomboedral diamond polytypes. The best known polytype other than cubic diamond is lonsdaleite (2H diamond) …”. Phelps [7] underlines that the theories concerning the meteoritic diamonds formation have been changing since new methods of diamond synthesis were developed. In the 1960s meteoritic diamonds were believed to be formed in the interiors of planetary bodies as a result of high pressure–temperature processes. After the development of shock wave diamond synthesis, the theory of impact formation of diamond became popular, especially because it was possible to form lonsdaleite existing in many meteorites. After the development of low-pressure methods of diamond synthesis (chemical vapour deposition CVD methods) and after the discovery of presolar diamonds, also theories of CVD-like diamonds formation became popular. Daulton et al. [8] reviews the theories concerning the presolar nanodiamonds origin. Among wider and more profound explanations, he describes that according to Lewis et al. [4] presolar nanodiamonds formed in the circumlstellar atmosphere of carbon
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Fig. 1. Samples of meteorites (ruler with the millimeter scale for meteorites sizes comparison): a) NWA XXX ureilite found in 2006 in Morocco and b) the graphite nodula from the Canyon Diablo iron meteorite.
stars, such as red giants, in the low-pressure conditions similar to the chemical vapour deposition (CVD) process. On the contrary, according to Tielens et al. [45] presolar nanodiamonds formed by highpressure shock metamorphism of amorphous carbon or graphite grains driven by high-velocity (grain–grain) collisions in interstellar shock waves associated with supernovae. Nanodiamonds could also form by UV annealing of small graphite particles, in type II supernova, or upon irradiation of carbonaceous grains by energetic particles released by supernovae. Daulton compares CVD nanodiamonds, nanodiamonds synthesized by shock methamorphism to nanodiamonds isolated from Murchison and Allende meteorites. With high resolution transmission electron microscopy (HRTEM), he studies differences and similarities of microstructural (nanostructural) growth features, such as morphology, polymorphic modifications, lattice defects (twin boundaries, dislocations, stacking faults, point defects) which record the physical conditions in diamond forming environments. This research indicates that the predominant mechanism for presolar nanodiamonds formation is a low-pressure CVD-type process (it is possible that nanodiamonds have many different origins from different astrophysical sources). Koscheev et al. [9–12] presents an application of synthetic detonation nanodiamonds instead of presolar meteoritic nanodiamonds in laboratory simulation experiments. Ultradispersed detonation diamonds (UDD) have the sizes of about 4 nm, so are similar to the presolar ones. Maul et al. [13] investigated a statistical growth behaviour of nanodiamonds in the vapour phase. They compare presolar nanodiamonds and larger synthetic diamonds obtained from vapour detonation processes. Laser ablation/ionization time-of-flight (TOF) mass spectrometry was used to record their mass distribution. The samples of Murchison, Allende and synthetic diamonds exhibit a lognormal mass distribution. This indicates a size-dependent molecular growth similar to chemical vapour deposition like processes. On the basis of thermodynamics and taking into consideration the surface properties, Raty and Galli [14] try to understand a similar size distribution (2–5 nm) of meteoritic nanodiamonds to those obtained by CVD or detonation methods.
Fig. 2. First-order Raman spectra of some carbon phases in four different places of NWA XXX ureilite found in 2006 in Morocco, the Raman bands at 1332 cm− 1 indicate the presence of diamond.
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Fig. 3. Second order Raman spectra of some carbon phases in two different places of NWA XXX ureilite found in 2006 in Morocco.
In our previous paper [1] we indicated that nanodiamonds can be formed under low pressure, with the assistance of electrons, in the CVD process, under similar conditions as in the space. 2. Experimental 2.1. Samples In this paper we present two meteorites: primitive achondrite — not classified NWA XXX ureilite (found in 2006 in Morocco) (Fig. 1a) and graphite nodula from the Canyon Diablo iron meteorite (Fig. 1b). We compare the carbonaceous matter from the meteorites to detonation nanodiamonds and nanodiamonds obtained by the RF PACVD method, and polycrystalline diamond obtained by the MW PACVD method.
The detonation diamonds were obtained by Danilenko [15,16]. He proposed and implemented (in 1962) ampoule-free synthesis with explosions in the explosion chamber instead of ampoule synthesis. Graphite was placed directly into a cylindrical charge consisting of the TG40 trotyl–hexogen mixture; the charge was enveloped in a water jacket to suppress graphitization and reduce the unloading rate of the synthesized diamond. The mean size of diamond nanocrystals were 2–4 nm. Typical carbon films formed by hydrocarbon decomposition with the Radio Frequency Plasma Activated Chemical Vapour Deposition (RF PACVD) are characterized by an amorphous structure with a few crystalline inclusions. In [17] it is assumed that the formation of crystalline inclusions [18] can be a source of nanocrystalline diamond coating, a promising relatively cheap material for many industrial applications. The nanocrystalline diamond layers consist
Fig. 4. Raman spectrum of the graphite nodula from the Canyon Diablo meteorite showing the presence of graphite as main mineral. The bands at 1358 and 1682 cm− 1 are D and G graphite bands, respectively.
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Fig. 5. Raman spectrum from the micro-region of the graphite nodula from the Canyon Diablo iron meteorite showing the presence of nanocrystalline hexagonal diamond lonsdaleite. The band at 1291 cm− 1 is wide and shifted from the diamond line 1332 cm− 1 that indicates a low perfection of the structure.
of aggregates of diamond nanocrocrystals, which were examined by Raman spectroscopy. Polycrystalline diamond was obtained with the microwave plasma CVD method [19]. 2.2. Raman spectroscopy Raman spectroscopy is a powerful technique for studying carbonasceous materials [1,2,20–23]. This method allows one to distinguish various forms of carbon such as diamond (monocrystalline, microcrystalline, nanocrystalline), graphite (with its different levels of order),
amorphous carbon, diamond-like carbon, fullerens, etc. Raman spectroscopy enables us to determine a crystallographic arrangement. Additional information about crystal sizes, stresses, structural perfection can be also obtained (broadening and shifts of the Raman peaks). Raman spectra were recorded using the confocal Raman microspectrometer T-64000 (Jobin–Yvon) equipped with the microscope BX-40 (Olympus). The 514.5 nm Ar line was used for sample excitation. The other parameters of spectra acquisition (time, laser power) were adjusted to obtain good quality spectra. The diameter of the laser beam was 1.5 µm, the light intensity across the beam was of Gaussian distribution.
Fig. 6. Raman spectra of Nanocrystalline Diamond Coating (NCD) obtained by the RF PACVD method [17].
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method permits only semi-quantitative and comparative analysis (a comparison of the intensity of peaks). In the investigations, an Optimass 8000 ICP-TOF-MS (Inductively Coupled Plasma Time of Flight Mass Spectrometer) produced by GBC from Australia with a laser ablation unit, LA, produced by CETAC Laser Ablation System from USA, were used. The action of high-energy laser beam on a solid results in the evaporation and removal of material in the form of neutral atoms and molecules, positive and negative ions from the surface of the solid exposed to this radiation. The use of the TOF analyzer in the ICP-MS method allows one to detect all the elements contained in the sample under testing simultaneously. 2.4. SEM-EDS The mean and local element composition of the samples was determined by the energy dispersive X-ray (EDX) method using an EDX Link 3000 ISIS X-ray microanalyser (Oxford Instruments) and an X-ray microprobe analyser EDX THERMO NORAN. Vega 5135 (Tescan) and HITACHI S-3000 N scanning electron microscopes were used to characterize a microstructure of the samples. Fig. 7. Raman spectra of Polycrystalline Diamond obtained by the MW CVD method.
3. Results 2.3. Laser Ablation Inductively Coupled Plasma Time of Flight Mass Spectrometry The LA-ICP-TOF-MS method (Laser Ablation Inductively Coupled Plasma Time of Flight Mass Spectrometry) is an analytical technique for the determination of trace elements and their isotopes in solid samples [24]. The action of high-energy laser beam on a solid results in the evaporation and removal of material in the form of neutral atoms and molecules, positive and negative ions from the solid surface exposed to this radiation. In chemical analysis, the pulse laser based on a solid such as neodym, Nd:YAG, has turned out to be very useful as it makes it possible to incorporate solid samples directly into plasma. It is utilized as a source of very high energy with specific properties and can be used for the analysis of various solids (conductive and nonconductive) with various sizes and shapes, where the laser beam can be focused on a very small surface with exceptionally precise location, while the evaporated material can be immediately analyzed. The studied samples do not need any preparation so a lot of time devoted to analysis is saved. Because of the difficulty in a selection of standards and certificated materials for suitable solid samples, this
Figs. 2 and 3 show the first and second order Raman spectra of the carbonaceous matter found in ureilite NWA XXX, Figs. 4 and 5 show the carbonaceous matter found in the graphite nodula from the iron meteorite Canyon Diablo. The meteorite samples are depicted in Fig. 1a) and b). Figs. 6–8 present the Raman spectra of the Nanocrystalline Diamond Coating obtained with the RF PACVD method, Polycrystalline Diamond obtained with the MW CVD method and UDD — nanodiamonds obtained with the detonation method, respectively. The measurements of the Laser Ablation Inductively Coupled Plasma Time of Flight Mass Spectrometry indicate that the carbon isotopic composition ratio 13C/12C = 0.01031 for the sample of ureilite NWA XXX and 13C/12C = 0.01017 for the graphite nodule from the Canyon Diablo meteorite. Using the energy dispesive X-ray (EDX) analyser, it is confirmed that the meteorite samples are multicompononent objects like terrestrial rocks. All the samples contain carbon in the form of various carbon phases and compounds. The mean carbon content in the graphite nodule from the Canyon Diablo iron meteorite (IAB coarse octahedrite) is 63%, and in the NWA XXX ureilite — 2.76%.
Fig. 8. Raman spectra of UDD — detonation nanodiamonds. We present for the first time the comparison of the examinations of the Raman spectroscopy of nanocrystalline diamond coating made by RF PACVD method, ultradispersed detonation diamonds, polycrystalline diamonds and meteoritic diamonds (achondrite — not classified ureilite NWA XXX found in Morocco in 2006 and graphite nodule from the Canyon Diablo iron meteorite).
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4. Discussion Ureilites [25,26] are achondrites composed of olivine and pigeonite mainly and they contain relatively large amounts of carbon occurring as graphite and diamond, often existing together. There are different hypothesis of diamond origin in ureilites: a HPHT process, a shock conversion of graphite during the parent body impact (widely accepted theory) or a CVD process in the solar nebula. In our sample of the NWA XXX the band at 1332 cm− 1, which was found in two points of the sample, indicates the presence of diamond. The other bands at 1355 cm− 1, around 1580 cm− 1 and the second order band around 2710–2730 cm− 1, indicate the presence of graphite. Thus, we have found the places in our sample where graphite and diamond exist together. The shifts of the graphite bands (first order 1580 cm− 1, 1582 cm− 1, 1580 cm− 1, 1577 cm− 1 and the second order 2730 cm− 1 and 2710 cm− 1) indicate that the meteoritic matter is not uniform, carbonaceous matter in one meteorite sample differs in different points of the meteorite. The differences are caused by the different order (disorder) of graphite in different points of the sample. Mostefaoui et al. [27] tested with the laser micro-Raman spectroscopy nine diamond grains of Bencubbin meteorite. They all exhibit the Raman one-phonon band near 1332 cm− 1 characteristic of diamond. However, the Bencubbin diamonds Raman band position is shifted from 1331.5 cm− 1 to 1325.6 cm− 1. The authors indicate an influence of the laser beam intensity on the degree of shift. “The higher the power of the laser, the lower the band position”. Greshake et al. [28] examined carbon phases in the ureilite Hammadah al Hamra 126 (S3) by the Raman spectroscopy technique. Their studies revealed the presence of diamond, however the broad diamond band is strongly shifted, the band position strongly depends on the relative intensity. At low relative intensities the band was observed at 1313 cm− 1, at the high ones it was shifted up to ~1290 cm− 1. This shift, in authors opinion, is probably caused by nanocrystalline diamond domains. In our case, it is probable that we have found the diamonds inside the graphite nodule from the iron Canyon Diablo meteorite. The diamond band in the Raman spectra at about 1291 cm− 1 is broad and shifted in comparison to “conventional” diamond at 1332 cm− 1. Broadening and shift are typical of nanocrystalline diamond. Some authors associate the existence of bands around 1150 cm− 1 and around 1450 cm− 1 with the presence of nanocrystalline diamond [17,20]. Kromka et al. [20] examined a diamond thin film grown with the HFCVD method by the Raman spectroscopy. They obtained four bands: “a weak band centred at about 1114 cm− 1, a broad band centred at 1325 cm− 1 with a left shoulder extending to 1114 cm− 1, a broad band centred around 1470 cm− 1, and a similarly broad band centred at 1580 cm− 1.” They thought that 1114 cm− 1 and 1470 cm− 1 bands “could be assigned to small size (1–2 nm) clusters (nanocrystalline diamond)”. Birrell et al. [29] think that the peaks at 1120 cm− 1 and 1450 cm− 1 in the Raman spectrum which were attributed previously to nanocrystalline diamond are rather connected with the presence of hydrogen at the grain boundaries (carbon–hydrogen bonds). They studied the transition from the nanocrystalline to microcrystalline diamond structure and they used visible and UV Raman among other techniques. Ferrari and Robertson [30,31] also argue that the peaks near 1150 cm− 1 and near 1450 cm− 1 should not be assigned to nanocrystalline diamond or other sp3-bonded phases. They think that these peaks are assigned to transpolyacetylene segments at grain boundaries and surfaces, so sp2-bonded configurations. The UV Raman spectra of Nanocrystalline Diamond Coating obtained with the RF PACVD technique (Fig. 6) show the existence of bands at 1139 cm− 1, 1332 cm− 1, 1444 cm− 1, 1528 cm− 1, 1600 cm− 1. As described above, 1139 cm− 1 and 1444 cm− 1 can be attributed to nanocrystalline diamond σsp3 bonds, however it is controversial. The
band at 1332 cm− 1 shows the presence of diamond σsp3 bonds, the broadening of this band indicates that the diamond phase is highly disordered. The band at 1528 cm− 1 shows the presence of carbides sp1 bonds. And the band at 1600 cm− 1 shows the presence of nanocrystalline graphite. The Raman spectra of our polycrystalline diamond sample obtained with the MW CVD method, show (as has been expected) the existence of narrow, strong peak at 1332 cm− 1 which indicates the presence of pure diamond. Raty and Galli [14] indicate that both extraterrestrial and terrestrial nanodiamonds are of similar sizes (2–5 nm) and show the presence of graphitic-like sites, possibly at the surface. Ultrananocrystalline diamond films could contain at the grain boundries about 2–5% of sp2-bonded carbon atoms. Ultradispersed diamonds (UDD) obtained with the detonation method, have a surface covered by a mixture of sp2- and sp3-bonded carbon atoms. The authors write: “we have proposed that nanoscale diamond obtained by detonation as well as that found in meteorites does indeed have a diamond core with a fullerene-like surface reconstruction, and we have called these carbon particles bucky diamonds. Several experimental studies of the annealing process of diamond nanoparticles have provided evidence of progressive formation of curved graphitic shells around a diamond core, resulting in onion-like structures”. Also Guillou and Rouzaud [32] and Braatz et al. [33] show possibility of nanodiamonds graphitization and obtaining onion-like structures under temperature. Indeed, the Raman spectra of our sample of detonation nanodiamonds show both the presence of sp3- and sp2-phases (Fig. 8). The broad peak at around 1320 cm− 1 indicates the presence of diamond. The graphite band could indicate the presence of graphite shell around the diamond core. The profound descriptions of the Raman spectra of carbonaceous matter, both terrestrial and extraterrestrial, can be found in several papers [20–23,27–31,34–36]. The LA-ICP-TOF-MS results of the carbon isotopic ratios of our meteorite samples show that the results are representative for our solar system [37]. We have not detected any places which have shown any isotopic anomalies with this method. Certain physical properties of extraterrestrial diamonds such as specific gravity, IR absorption and structural perfection make them different from terrestrial diamonds. The bulk density of presolar diamonds is only 2.22–2.33 g/cm3 compared with 3.51 g/cm3 for normal diamond [38]. Fine greyish diamond grains found in Novo Urei achondrite (ureilite), constituted about 1% of the total weight of meteorite, exhibited bulk density in the range 2.89–3.3 g/cm3, whereas black and white, and greyish-brown diamond grains in the Canyon Diablo showed density 3.3 g/cm3 [39]. Hexagonal diamond lonsdaleite has density from 3.2 to 3.3 g/cm3, Mohs hardness of 7–8, and an index of refraction from 2.40 to 2.41 [40]. Hexagonal and cubic diamonds may coexist in meteorites. In the Canyon Diablo iron meteorite volume fractions of hexagonal and cubic diamonds are: 30% hexagonal phase and 70% cubic phase, and in the Goalpara meteorite diamonds are mainly cubic (10% hexagonal phase and 90% cubic phase) [41]. Both these meteorites were formed by impact shock from well-crystallized graphite existing within the meteorites before impact, but diamond-producing impact of the Goalpara meteorite was a collision in space, whereas the Canyon Diablo diamonds were produced by collision of this meteorite with the Earth [41]. In Havero and other ureilites intergrowths of graphite and diamond were observed [42]. This property is a proof that they have experienced variable but typically intense shock metamorphism, and graphite, the original carbon mineral, has been partly transformed by shock into its polymorphs, diamond and lonsdaleite [42]. Presolar diamonds have an extremely fine-grained structure [4]. The distribution of twin microstructure and an absence of dislocations suggest that most of the interstellar diamond formed by CVD processes [38,43].
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Various crystalline forms called polytypes have been noted in terrestrial and extraterrestrial diamonds. Extraterrestrial diamonds show cubic, hexagonal and rhombohedral symmetry, whereas terrestrial diamonds are mainly cubic (e.g. [6]). There is only one form of cubic diamond (3C), but there are several hexagonal polytypes of which most frequent is lonsdaleite 2H, and several rhombohedral polytypes (e.g. 21R form) [6]. In diffraction patterns of carbon phases of various ureilites, also other hexagonal and rhombohedral carbon phases are present apart from cubic and 2H phases. Novo Urei ureilites contain only cubic and 2H diamond, Dyalpur show 6H, 8H and 10H polytypes, Goalpara contain 8H, 10H and 21R polytypes in addition to the cubic and 2H phases [6,44]. Diamonds in the Canyon Diablo and in ALH A77283 iron meteorites apart from 3C and 2H exhibit also 21R polytype [6]. There are many types of diamond in many types of meteoritic and interstellar material: in meteorities that exhibit strong alteration, deformation and shear (ureilites and achondrites), in iron meteorites, and in relatively unaltered meteorites such as chondrites. The variation in polytype abundance reflects the nature of the host and enables one to analyze the conditions of condensation, nucleation and crystallisation [6]. 5. Conclusions The experiments have proven that an application of the nondestructive method of the confocal Raman micro-spectroscopy revealed the presence of diamond in both terrestrial and extraterrestrial materials. Diamond is present in the sample of ureilite NWA XXX, nanodiamonds were discovered in the graphite nodula from the iron Canyon Diablo meteorite. Diamonds peaks in the Raman spectra were also discovered in the samples of NCD coatings obtained with the RF PACVD method and in the sample of detonation nanodiamonds UDD. Acknowledgement Supported by ERA-NET MNT/98/2006 project. References [1] A. Karczemska, M. Kozanecki, M. Szurgot, A. Sokołowska, S. Mitura, Diam. Relat. Mater. 16 (2007) 781. [2] M. Szurgot, A. Karczemska, M. Kozanecki, in: S. Mitura, P. Niedzielski, B. Walkowiak (Eds.), Nanodiam, PWN, Warsaw, 2006, p. 259. [3] O.R. Norton, The Cambridge Encyclopedia of Meteorites, Cambridge Univ., Cambridge, 2002. [4] R.S. Lewis, M. Tang, J.F. Wacker, E. Anders, E. Steel, Nature 326 (1987) 160. [5] K. Lodders, S. Amri, Chem. Erde 65 (2005) 93. [6] http://www.lpi.usra.edu/publications/abstracts.shtml: A.W. Phelps; Lunar Planet. Sci. XXX (1999), Abstract #1749. [7] http://www.lpi.usra.edu/publications/abstracts.shtml: A.W. Phelps; Lunar Planet. Sci. XXX (1999), Abstract #1753. [8] T.L. Daulton, D.D. Eisenhour, T.J. Bernatowicz, R.S. Lewis, P.R. Buseck, Geochim. Cosmochim. Acta 60 (1996) 4853.
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