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Novel High-Performance CVD Coatings for Machining Applications

, R., Köpf, A., Weissenbacher, R.: Physica Status Solidi C, vol. 12, 2015, p. 1043 [18] Bonetti-Lang, M., Bonetti, R., Hintermann, HE. In: Proc 8 th Int Conf on CVD, 1981, p. 606 [19] Rauchenwald, E., Lessiak, M., Weissenbacher, R., Haubner, R.: (to be published). [20] Osada, A., Danzinger, M., Haubner, R., Lux, B.: Journal de Physique IV, Coll.C2, vol. 1, 1991, p. 557 [21] Iiyoshi, H.: Doctoral Thesis. Vienna : TU, 1990 [22] Altena, H., Lux, B.: Int. J. Refract. Met. Hard Mater., vol. 6, 1987, p. 53 [23] Peng, J., Danzinger, M

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Optoelectronic system for investigation of CVD diamond/DLC layers growth

References May P. W., Tsai H. Y., Wang W., Smith J. A.: Deposition of CVD Diamond onto GaN, Diam. Rel. Mat. 15(4-8) (2006) pp. 526-530. Hsiao-Kuo C., Sung J. C.: The rapid growth of thin transparent films of diamond, Diam. Rel. Mat. 10 (2001) pp. 1584. May P. W.: The New Diamond Age?, Science 319 (2008) pp. 490. Smietana M., Szmitdt J., Korwin-Pawlowski M. L., Bock W. J.: Diamond-like carbon films deposited onto optical fibres and waveguides

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Thermoluminescence properties of undoped diamond films deposited using HF CVD technique

References [1] SPEAR K.E., DISMUKES J.P., Synthetic diamond: emerging CVD science and technology, John Wiley & Sons, New York, 1994. [2] PAN L., KANIA D., Science, 255 (1992), 830. [3] PILIERO M., HUGTENBURG R., RYDE S., OLIVER K., Radiat. Phys. Chem., 104 (2014), 10. [4] ZAKARI Y., MAVUNDA R., NAM T., KEDDY R., Physcs. Proc., 37 (2012), 950. [5] LANSLEY S.P., GAUDIN O., WHITFIELD M.D., MCKEAG R.D., RIZVI N., JACKMAN R.B., Diam. Relat. Mater., 9 (2000), 195. [6

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CVD carbon powders modified by ball milling

Abstract

Carbon powders produced using a plasma assisted chemical vapor deposition (CVD) methods are an interesting subject of research. One of the most interesting methods of synthesizing these powders is using radio frequency plasma. This method, originally used in deposition of carbon films containing different sp2/sp3 ratios, also makes possible to produce carbon structures in the form of powder. Results of research related to the mechanical modification of these powders have been presented. The powders were modified using a planetary ball mill with varying parameters, such as milling speed, time, ball/powder mass ratio and additional liquids. Changes in morphology and particle sizes were measured using scanning electron microscopy and dynamic light scattering. Phase composition was analyzed using Raman spectroscopy. The influence of individual parameters on the modification outcome was estimated using statistical method. The research proved that the size of obtained powders is mostly influenced by the milling speed and the amount of balls. Powders tend to form conglomerates sized up to hundreds of micrometers. Additionally, it is possible to obtain nanopowders with the size around 100 nm. Furthermore, application of additional liquid, i.e. water in the process reduces the graphitization of the powder, which takes place during dry milling.

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Temperature dependence of stress in CVD diamond films studied by Raman spectroscopy

Abstract

Evolution of residual stress and its components with increasing temperature in chemical vapor deposited (CVD) diamond films has a crucial impact on their high temperature applications. In this work we investigated temperature dependence of stress in CVD diamond film deposited on Si(100) substrate in the temperature range of 30 °C to 480 °C by Raman mapping measurement. Raman shift of the characteristic diamond band peaked at 1332 cm-1 was studied to evaluate the residual stress distribution at the diamond surface. A new approach was applied to calculate thermal stress evolution with increasing tempera­ture by using two commonly known equations. Comparison of the residts obtained from the two methods was presented. The intrinsic stress component was calculated from the difference between average values of residual and thermal stress and then its temperature dependence was discussed.

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Electrical properties and Mott parameters of polycrystalline diamond films synthesized by HF CVD method from hydrogen/methanol gas mixture

Abstract

The influence of diamond crystallinity and preferred orientation on electronic conductivity of synthetic diamond films grown by hot filament chemical vapor deposition (HFCVD) was investigated. The CVD diamond films of different morphologies and crystallite sizes varying from 36 nm to 67 nm, measured in h2 2 0i direction were considered. The charge transport mechanism in the diamond samples was studied using temperature dependent DC conductivity measurements. The obtained results showed that in the temperature range of 90 K to 300 K charge transport is realized via Variable Range Hopping (VRH, m = 1/4) mechanism. Using VRH model, the Mott parameters were evaluated i.e. density of states at Fermi level N(EF) (0.22 × 1015 eV-1·cm-3 to 1.7 × 1015 eV-1·cm-3), hopping energy W (43.5 meV to 142.3 meV) and average hopping distance R (1.49 × 10-5cm to 2.56 × 10-5cm). It was shown that above mentioned parameters strongly depend on diamond film preferential orientation.

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Study of CVD diamond layers with amorphous carbon admixture by Raman scattering spectroscopy

Abstract

Raman spectroscopy is a most often used standard technique for characterization of different carbon materials. In this work we present the Raman spectra of polycrystalline diamond layers of different quality, synthesized by Hot Filament Chemical Vapor Deposition method (HF CVD). We show how to use Raman spectroscopy for the analysis of the Raman bands to determine the structure of diamond films as well as the structure of amorphous carbon admixture. Raman spectroscopy has become an important technique for the analysis of CVD diamond films. The first-order diamond Raman peak at ca. 1332 cm−1 is an unambiguous evidence for the presence of diamond phase in the deposited layer. However, the existence of non-diamond carbon components in a CVD diamond layer produces several overlapping peaks in the same wavenumber region as the first order diamond peak. The intensities, wavenumber, full width at half maximum (FWHM) of these bands are dependent on quality of diamond layer which is dependent on the deposition conditions. The aim of the present work is to relate the features of diamond Raman spectra to the features of Raman spectra of non-diamond phase admixture and occurrence of other carbon structures in the obtained diamond thin films.

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Preparation of carbon nanotubes using cvd CVD method

References Balogh, Z., Halasi, G., Korbély, & Hernadi, K. (2008). CVD-syntesis of multiwall carbon nanotubes over potassium-doped supported catalysts. Appl. Catal. A: General 344, 191-197. doi:10.1016/j.apcata.2008.04.019. Singh, B. K., Ryu, H., Rajeev, C. C., Nguyen, D. H., Park, S. J., Kim, S. & Lee, J. R. (2006). Growth of multiwalled carbon nanotubes from acetylene over in situ formed Co nanoparticles on MgO support. Solid State Commun. 139, 102-107. doi:10.1016/j.ssc.2006

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Systematic study on synthesis and purification of double-walled carbon nanotubes synthesized via CVD

Abstract

Carbon nanotubes have unique properties, such as thermal and electrical conductance, which could be useful in the fields of aerospace, microelectronics and biotechnology. However, these properties may vary widely depending on the dimensions, uniformity and purity of the nanotube. Nanotube samples typically contain a significant percentage of more allotropes forms of carbon as well as metal particles left over from catalysts used in manufacturing. Purity characterization of double-walled carbon nanotubes (DWCNTs) is an increasingly popular topic in the field of carbon nanotechnology. In this study, DWCNTs were synthesized in a catalytic reaction, using Fe:MgO as catalyst and methane or methane/ethanol as carbon feedstock for chemical vapor deposition (CVD). The addition of ethanol as carbon feedstock allowed to investigate the influence of oxygen on the sample quality. The purification of the as-produced material from the metallic particles and the catalyst support was performed by sonication in an acid solution. The influence of the duration of the acid treatment using ultrasound on the sample purity was investigated, and the optimal value of this parameter was found. Transmission electron microscopy (TEM) images confirmed the removal of impurities and served to elucidate the morphology of the samples. The purity of carbon nanotubes was analyzed using thermal gravimetric analysis (TGA). The Raman spectra of the samples, as a measure of the concentration of defects, were also reported.

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Determination of temperature dependent parameters of zero-phonon line in photo-luminescence spectrum of silicon-vacancy centre in CVD diamond thin films

optoelectronic transitions in single crystal CVD diamond”, Journal of Physics. Condensed Matter: An Institute of Physics Journal, vol. 25, No. 27, 2013, pp. 275801. [4] M. Marton, M. Mikolášek, J. Bruncko, I. Novotný, T. Ižák, M. Vojs, H. Kozak, M. Varga, A. Artemenko, and A. Kromka,” Fabrication and Characterization of N-Type Zinc Oxide/P-Type Boron Doped Diamond Heterojunction”, Journal of Electrical Engineering, vol. 66, No. 5, 2015,. [5] T. D. Merson, S. Castelletto, I. Aharonovich, A. Turbic, T. J. Kilpatrick and A. M. Turnley

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