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EP1098845A2 - Nouvelle classe de matieres a structure de diamants et techniques de synthese de telles matieres - Google Patents

Nouvelle classe de matieres a structure de diamants et techniques de synthese de telles matieres

Info

Publication number
EP1098845A2
EP1098845A2 EP99926376A EP99926376A EP1098845A2 EP 1098845 A2 EP1098845 A2 EP 1098845A2 EP 99926376 A EP99926376 A EP 99926376A EP 99926376 A EP99926376 A EP 99926376A EP 1098845 A2 EP1098845 A2 EP 1098845A2
Authority
EP
European Patent Office
Prior art keywords
diamond
materials
substrate
dispersions
materials according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99926376A
Other languages
German (de)
English (en)
Inventor
Maria Letizia Terranova
Marco Uni. degli S. di Roma"La Sapienza" ROSSI
Vito Università di Roma "Tor Vergata" SESSA
Susanna Univer. di Roma "Tor Vergata" PICCIRILLO
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Universita degli Studi di Roma Tor Vergata
Universita degli Studi di Roma La Sapienza
Original Assignee
Universita degli Studi di Roma Tor Vergata
Universita degli Studi di Roma La Sapienza
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Universita degli Studi di Roma Tor Vergata, Universita degli Studi di Roma La Sapienza filed Critical Universita degli Studi di Roma Tor Vergata
Publication of EP1098845A2 publication Critical patent/EP1098845A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
    • C01B21/0605—Binary compounds of nitrogen with carbon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
    • C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/04—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of carbon-silicon compounds, carbon or silicon

Definitions

  • the present invention refers to diamond-based composite materials, in particular to composite materials consisting of sub-micrometric or nanometric dispersions of metal elements, semiconductors and inorganic compounds thereof in diamond-structured carbon polymorphic matrices.
  • the diamond thanks to its excellent mechanical, thermal, optical, electric and chemical properties, can be considered not only as a fully qualified material for technologically advanced applications and competitive when compared to traditional materials, but also in some cases as the only available option.
  • a specific sector of diamond research is directed towards diamond doping, creating donor and acceptor centers which, giving rise to type "n” and type “p” electric conductivity respectively, confer characteristics of a "semiconductor” to the diamond.
  • the most commonly used doping agent is B, which is inserted as a substituent into the diamond lattice during the gaseous phase deposition process, or implanted into the already grown film.
  • B which is inserted as a substituent into the diamond lattice during the gaseous phase deposition process, or implanted into the already grown film.
  • diamond-based composite materials consisting of sub-micrometric or nanometric dispersions of metal elements, semiconductors and inorganic compounds thereof in diamond-structured and diamond-like carbon polymorphic matrices make it possible to overcome these known technical problems.
  • Composite materials as now defined are the first object of this invention.
  • Another object of this invention is a process and the relevant apparatus for the preparation of these materials.
  • FIG. 1 illustrates the apparatus for the preparation of the composite materials of this invention.
  • This apparatus was specifically designed for the synthesis of the new materials.
  • the synthesis technique according to this invention provides the connection of a hot filament (HF) or microwave (MW) CVD (Chemical
  • Vapour Deposition reactor to a system for controlled introduction of powders and/or volatile precursors, in order to obtain a new class of carbon materials.
  • the proposed methodology makes it possible to obtain a vast spectrum of diamond-based composite materials consisting of sub- micrometric or nanometric dispersions of metal elements, semiconductors and their inorganic compounds in diamond-structured carbon polymorphic matrices.
  • the materials are deposited in the form of coatings, films and thin layers on suitable substrates.
  • the matrix it is possible to independently modulate its crystallographic characteristics (degree of crystallinity, preferential orientation, phase purity). Furthermore, considering the variety of the components (metal elements, semiconductors and inorganic compounds thereof) which can be inserted into the diamond matrix, and the possibility to modify the composition of the gaseous phase which acts as precursor, it can be seen how the synthesis methodology described herein is highly versatile and makes it possible to synthesise a vast range of composite materials.
  • the formation on the substrate surface of a composite ayer with concentration gradient containing a dispersion of the same material as the substrate and where the percentage of the diamond phase progressively increases towards the exterior can effectively contrast the poor adhesion of the diamond film to the substrate, releasing stress and therefore improving adhesion of the coating to the substrate.
  • Another advantage of the composite materials subject of this invention is the elimination of, or reduction in, the problems related to the diamond-hostile layer interface. In this case too, it is useful to previously deposit composite intermediate layers where the concentration of metal diminishes gradually. In this way, it is possible to modulate the C-metal interaction, so generating an interface which acts as a buffer and makes it possible to obtain a diamond coating effectively anchored to the hostile substrate by a carbide-like layer.
  • the diamond-matrix layers containing dispersions of some transition metals show a rise in temperature ( ⁇ T) related to the diamond/graphite phase transition.
  • ⁇ T rise in temperature
  • This ⁇ T may be varied according to the nature and concentration of the inserted metal, and to the degree of carburization reached during the process. This makes it possible to use the composite materials in cutting instruments even in the case of "hard" materials.
  • the structural characteristics of the dispersions define the charge transport properties, modifying the electric resistivity which goes from values typical of the diamond (approx. 10 16 Ohm cm) to values typical of a good conductor (10 "3 - 10 "6 Ohm cm).
  • diamond-based composite layers can combine the exceptional tribological, mechanical and chemical (high inertia) properties of the diamond with the characteristics of a conductor.
  • electric or micro-electronic devices which may be discrete, integrated or hybrid, constituted by or including and/or coated with conductive diamond layers, can be used in all those situations where bio-compatibility is required (on-site medical diagnosis, etc.).
  • the introduction of metallic elements, semiconductors and their inorganic compounds makes it possible to modulate the electronic affinity of the diamond-based films.
  • the composite materials are useful for the coating of metallic prostheses to be planted in the human body, for example the thighbone upper joint, orthopaedic prostheses, orthodontic implants, etc.
  • the introduction of chemical species in a polycrystalline diamond matrix also alters its optical properties.
  • the diamond/metal composite may show characteristics of a superconductor.
  • IR fields, near IR, UV or visible at room temperature are promising candidates for use in the solid state laser sector and electro-optical devices.
  • the deposition apparatus schematically illustrated in the diagram is of a new conception and has been specifically designed for deposition of carbon-based mixed phases.
  • the configuration given makes it possible to introduce into the synthesis chamber ( 1), in a controlled and repeatable manner, metal elements, semiconductors and inorganic compounds thereof both in the form of volatile compounds and sub-micrometric powders.
  • the powders (pure elements or compounds) or the volatile compounds are contained in a tank (8) and are transferred to the synthesis chamber by means of a device (2) which includes a system of gas flows (3,5) which makes it possible to control the de-nsity of the powders (or vapours) present in the gas.
  • the concentration of the particles in the gaseous flow is measured in two areas (separated by a flow measuring and control system), by means of two particle counters (4), based on laser and controlled by computer.
  • the measurement readings are used to operate the various control valves present.
  • the system ensures control of the quantity of powders (or vapours) introduced into the synthesis chamber, according to a prefixed scheme for each single experiment.
  • the described system is produced in quartz as far as the external part of the chamber is concerned.
  • the part of the system for introduction inside the chamber is in molybdenum.
  • Uniform distribution of metals on the entire carbon-based film deposition area is carried out by means of a particular geometrical configuration of the final part of the introduction system (7), schematically illustrated in the insert to the diagram.
  • Another important characteristic is the system to control the temperature of the substrate which includes a suitable heating device, at least one thermocouple and means for temperature control.
  • the growth apparatus described herein makes it possible to control the size of the precipitates and their dispersion in the carbon matrix and, simultaneously, the structure and composition of the carbon phases.
  • By varying the process parameters it is possible to introduce the metal elements, semiconductors and inorganic compounds thereof into the carbon matrix in the form of isolated nano-clusters or micrometric clusters linked in irregular chains.
  • the apparatus of this invention in accordance with the common knowledge in the art of chemical deposition in the vapour phase (CVD), is provided with all devices and means necessary for this process, such as vacuum devices, sample loading, flow controls, etc.
  • the temperature of the substrate during deposition is between 500 and 950°C
  • the pressure in the cell during deposition is between 30 and 100 torr
  • the flow of the hydrocarbon/hydrogen mixture in the cell is between 50 and 300 cm 3 /min
  • the hydrocarbon/hydrogen ratio in the flow is between 0.5 and 3%
  • the carrier gas conventionally chosen among nitrogen and noble gases, is between 10 and 120 cm 3 /min.
  • the substrates Before introduction into the chamber, the substrates should be preferably treated by means of abrasion with powders and diamond paste and cleaned with mixtures, for example acetone-based, in an ultrasound bath.
  • the apparatus of this invention can be used for the synthesis of another super-hard carbon material, C 3 N 4 .
  • the crystalline shape ( ⁇ -hexagonal) of this material on the basis of theoretical estimates, should possess mechanical characteristics (approx. 400 Gpa) better than those of the diamond. It should be pointed out that experimental measurements do not exist for a material which, up to now, seems to have been obtained in only a few (and controversial) experiments and, in any case, in quantities which do not allow direct measuring.
  • N 2 as a carrier gas
  • the deposition conditions are the following: Hot filament CVD chamber; temperature of Ta filament (diameter 0.3 mm): 2180°C; filament-substrate distance: 6mm; substrate: Si (100).
  • the film so obtained was characterised by the following properties: COMPOSITIONAL carried out by means of XPS (X-ray Photoelectron Spectroscopy): in the spectra appears the characteristic signal of C (Is) and those of the Nd at 979-983 eV (relative to the state 3d (5/2) ) and at 1001-1006 (relative to the state 3d (3/2) ).
  • COMPOSITIONAL carried out by means of XPS (X-ray Photoelectron Spectroscopy): in the spectra appears the characteristic signal of C (Is) and those of the Nd at 979-983 eV (relative to the state 3d (5/2) ) and at 1001-1006 (relative to the state 3d (3/2) ).
  • STRUCTURAL carried out by means of RHEED Reflective High Energy Electron Diffraction: the diffraction patterns reveal the presence of the diamond phase (spatial group Fd3m), in polycrystalline form without the presence of preferential orientation.
  • An analysis of the diffraction signals underlines the presence of other phases consisting of dispersed nano-crystalline grains, identified as Nd and Nd oxides.
  • ELECTRICAL measurement of the electrical characteristics, carried out with the Pauw method in the temperature range of 100-500 K, yielded conductivity values between 10 +2 and 10 +3 (ohm "1 cm “1 ).

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Carbon And Carbon Compounds (AREA)
  • Lubricants (AREA)

Abstract

L'invention se rapporte à des matières composites à structure de diamants qui sont constituées de dispersions sub-microniques ou nanométriques d'éléments métalliques, de semi-conducteurs et de leurs composés inorganiques dans des matrices polymorphes de carbone ayant la structure du diamant. L'invention se rapporte également aux techniques et au dispositif de préparation de ces matières.
EP99926376A 1998-05-26 1999-05-24 Nouvelle classe de matieres a structure de diamants et techniques de synthese de telles matieres Withdrawn EP1098845A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
ITMI981159 1998-05-26
ITMI981159 ITMI981159A1 (it) 1998-05-26 1998-05-26 Nuova classe di materiali a base diamante e tecniche per la loro sintesi
PCT/EP1999/003547 WO1999061371A2 (fr) 1998-05-26 1999-05-24 Nouvelle classe de matieres a structure de diamants et techniques de synthese de telles matieres

Publications (1)

Publication Number Publication Date
EP1098845A2 true EP1098845A2 (fr) 2001-05-16

Family

ID=11380099

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99926376A Withdrawn EP1098845A2 (fr) 1998-05-26 1999-05-24 Nouvelle classe de matieres a structure de diamants et techniques de synthese de telles matieres

Country Status (4)

Country Link
EP (1) EP1098845A2 (fr)
AU (1) AU4366399A (fr)
IT (1) ITMI981159A1 (fr)
WO (1) WO1999061371A2 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL1019781C2 (nl) * 2002-01-18 2003-07-21 Tno Deklaag alsmede werkwijzen en inrichtingen voor de vervaardiging daarvan.

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5352493A (en) * 1991-05-03 1994-10-04 Veniamin Dorfman Method for forming diamond-like nanocomposite or doped-diamond-like nanocomposite films
DE4210508C1 (en) * 1992-03-31 1993-04-08 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung Ev, 8000 Muenchen, De Mixed diamond - silicon carbide coating with good adhesion - consists of intimate mixt. of diamond phase and cubic beta silicon carbide phase, which can vary across coating thickness
US6080470A (en) * 1996-06-17 2000-06-27 Dorfman; Benjamin F. Hard graphite-like material bonded by diamond-like framework

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9961371A3 *

Also Published As

Publication number Publication date
WO1999061371A8 (fr) 2000-02-24
WO1999061371A3 (fr) 2000-04-27
AU4366399A (en) 1999-12-13
WO1999061371A2 (fr) 1999-12-02
ITMI981159A1 (it) 1999-11-26

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