ES2364773B1 - DEVICE AND PROCEDURE FOR MANUFACTURE OF NANOPARTICLES. - Google Patents

Abstract

Device and method of manufacturing nanoparticles. # A device for manufacturing nanoparticles by means of ionic bombardment techniques to various targets is described. Said device constitutes a source of aggregates of more than one material that allows the manufacture of nanoparticles with variable and controlled chemical composition, of controlled size and also in a "core-shell" structure.

Description

Device and procedure for manufacturing nanoparticles.

Object of the invention

The present invention relates to the field of nanoparticle manufacturing, more specifically to the manufacture of nanoparticles by physical techniques.

The object of the invention consists of a source of aggregates to generate particles of controlled size, with controlled and variable chemical composition, and / or "core-shell".

Background of the invention

The manufacture of nanoparticles is in full expansion due to its possible technological applications. Among the manufacturing methods, chemical methods and physical methods can be distinguished. In this proposal we are interested in a physical method of manufacturing nanoparticles whose device is called “source of aggregates”, or “Ion Cluster Source -ICS” in its Anglo-Saxon nomenclature. There is a wide variety of ICS that differ slightly in their design, but the operation of all of them can be summarized as follows: it is a gas or ion plasma of a material, generated in a controlled atmosphere of a neutral gas ( in general Ar or mixture of Ar and He) that favors the aggregation of the ions of the material to generate particles.

There are currently 2 English companies that sell ICS. Its commercialization began in 2001, and in all cases commercial ICS are based on the physical phenomenon of ablation or sputtering.

In commercial ICS, a plasma of a material torn from a target is created by the process of ionic bombardment or sputtering generated by a magnetron. The magnetron is connected (by means of the connection flange) to an aggregation zone, in which a high pressure of a gas called aggregation is injected, which can be argon

or a mixture of argon and helium. Due to the pressure in the aggregation zone, the ions torn from the target have a reduced mean free path and collide with each other thus forming aggregates. The ICS is connected to another vacuum system or ultra high vacuum where the particles can be deposited on a substrate after having traveled the aggregation zone.

Particle size control is achieved by varying different parameters such as the magnetron's working power, the gas pressure in the aggregation zone, and the magnetron position within the aggregation zone. The size of the aggregates can also be selected more precisely by adding a quadrupole fi lter between the ICS and the vacuum hood (where the particles are deposited).

Currently, in addition to the ICS, there is no other physical method of manufacturing nanoparticles of controlled size in ultra high vacuum or vacuum with which the manufacturing conditions of the nanoparticles and the conditions of the substrate on which the deposits are deposited can be independently controlled. nanoparticles. In fact, with the ICS, the manufacturing parameters of the nanoparticles are adjusted independently of the substrate conditions, which can be of any material, with any type of surface finish and at any temperature. It should also be noted that the physical sputtering process used in commercial ICS is the same as that used for the manufacture of hard drives. Therefore the sputtering process is a process routinely used in the industry.

An important parameter that cannot be controlled or modified with this method of manufacturing nanoparticles is its chemical composition. The chemical composition of the nanoparticles is given by the initial composition of the blank and by the sputtering process. In the case of alloy targets, the final composition of the particles is given by the differential sputtering processes of the elements that form the alloy of the target. As far as we know, there is no solution to overcome this severe limitation of ICS, either at the laboratory scale or at the commercial scale. In this proposal we present an innovative design of ICS that would allow precise control of the chemical composition of nanoparticles, thus extending the capabilities of ICS to levels never previously achieved.

Description of the invention

In the device object of the invention, the only magnetron present in known ICSs - sputtering, sputtering or ionic bombardment - in general 2 inches in diameter (5.08 cm), is replaced by several magnetrons. The number and size of the magnetrons can be modified according to the needs of each application using a connection flange to connect the magnetrons.

By varying the working powers and the gas flows of each magnetron, the plasma composition that is formed in the aggregation zone inside the chamber of the device object of the invention can be adjusted, thus allowing the control of the chemical composition of the aggregates and the nanoparticles that are formed. Since the control of the power of the magnetrons is continuous, it is thus possible to continuously adjust the concentrations of the ions in the aggregation zone, and therefore the final composition of the nanoparticles. The gases injected into the magnetrons and in the aggregation zone are not limited to Ar or a mixture of Ar and He, but may include other gases of interest, such as oxygen and / or nitrogen, to promote oxidation or nitriding of the materials during the nanoparticle manufacturing process.

On the other hand, the device object of the invention has individual translation systems for each magnetron. Said translation systems allow individual positioning of each magnetron in the aggregation zone, to favor the nucleation of a first material whose magnetron is positioned further away from the device's exit hole. Being further from the device's exit hole, the ions of the first material are nucleated before crossing the plasma of a second material, generated by a second magnetron positioned closer to the device's exit hole. The transit of the nanoparticles of the first material through the plasma of the second material results in the coating of the nanoparticles of the first material by a layer of the second material and, therefore, the manufacture of nanoparticles with a core formed by the first material and A crust of the second material. This type of nanoparticles are called "onion" or "core-shell" nanoparticles.

As described above, the device object of the invention is based, on the one hand, on the replacement of the only magnetron that currently equips the ICS by several magnetrons and, on the other hand, on which each magnetron has an individual system of positioning and translation within the aggregation zone that allows said magnetrons to be positioned relative to the exit orifice of the defined aggregation zone in the device chamber. The device allows, with the control of the powers and positions of each magnetron, to generate nanoparticles of variable chemical composition and nanoparticles of the “core-shell” type of high purity, since the manufacturing process using the device object of the invention is carried out in Ultra high vacuum conditions and controlled atmosphere. Said control of the chemical composition and said structure of the nanoparticles allows monitoring their physicochemical properties according to the requirements of each of their applications. For the overall positioning of the magnetrons connected to the aggregation zone by means of a flange, the device has a transfer device that allows the magnetron set to be located or moved at the same time.

The physical process of sputtering with magnetrons that is used industrially to make coatings and manufacture hard drives allows to generate a plasma from a target of any material, this being a conductor, semiconductor, insulator, superconductor, piezoelectric, etc. The device object of the invention allows to manufacture nanoparticles of any material with controlled chemical composition and also with the "core-shell" structure.

An application of the device object of the invention is its use for the manufacture of nanoparticles of magnetic alloys for high data storage density mentioned above, in digital data storage devices such as hard drives. By using the device object of the invention, magnetic nanoparticles of sizes smaller than the magnetic domains that are currently used to store information on hard drives can be generated. The control of particle size below the dimensions currently managed in the data storage industry allows to increase the density of magnetic domains and therefore the density of stored information. On the other hand, the control of the chemical composition of the nanoparticles allows the magnetic properties of the nanoparticles to be finely adjusted

or the magnetic domains, to obtain for example high essential magnetic anisotrophies in the data storage devices.

Another application of the device object of the invention is its use in the manufacture of superparamagnetic nanoparticles for medical applications: with the device object of the invention, coreshell particles can be generated with an outer layer of gold whose functionalization with drugs would confer a great interest on them. transport of medications in specific areas of the body.

The device object of the invention is also applicable in:

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Manufacture of gold-coated superparamagnetic nanoparticles to subsequently anchor organic molecules containing drugs to the outer layer of gold. The paramagnetic nature of the particles allows their guidance in the human body through magnetic fields to the area where drugs to fight tumors, infections, etc. are subsequently released.

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Manufacture of semiconductor nanoparticles for photovoltaic applications: nanoparticles are currently inserted into photovoltaic devices with the intention of, for example, increasing the effective surface of photovoltaic panels. With the device object of the invention, coatings formed by photovoltaic semiconductor nanoparticles can be generated very easily without the need for chemical treatments. Control of the chemical composition and density of the nanoparticles would allow the efficiency of photovoltaic collectors to be finely adjusted.

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Manufacturing of core-shell nanoparticles for sensor applications: a new generation of biological sensors based on magnetoplasmonic effects is currently being developed. These new sensors will have higher sensitivities than those currently on the market. Its structure consists of magnetic nanoparticles embedded in dielectric matrices that in turn are covered with gold. All the sensitivity of the sensor lies in the coupling of the plasmon of the magnetic particles with the plasmon of gold. With the device object of the invention, core-shell particles such as Co-Au can be generated in which the coupling in the plasmons of the magnetic material (Co) and Au will be optimal, thus increasing the sensitivity of the sensors.

Description of the drawings

To complement the description that is being made, and in order to help a better understanding of the characteristics of the invention, according to a preferred example of practical implementation thereof, a set of drawings is attached as an integral part of said description. where, for illustrative and non-limiting purposes, the following has been represented:

Figure 1.- Shows a scheme of the state of the art.

Figure 2.- Shows a schematic view of the device object of the invention where magnetrons are appreciated.

Figure 3.- Shows a section of the device object of the invention where magnetrons are appreciated.

Figure 4.- Shows a scheme of the geometry of the device object of the invention con fi gured for the manufacture of nanoparticles of variable chemical composition.

Figure 5.- Shows a section of the device object of the invention where the magnetrons positioned are appreciated.

Preferred Embodiment of the Invention

In view of the figures, some examples of the preferred embodiment of the device (1) object of this invention are described below.

Below we detail the procedures for the manufacture of nanoparticles of variable chemical composition and the manufacture of onion or core-shell nanoparticles on a substrate previously introduced in a chamber of the device (1).

Example 1

Procedure for manufacturing nanoparticles of variable chemical composition

For the manufacture of this type of nanoparticles, magnetrons (2) of the device are positioned together

(1) to generate the ions of materials A, B, C (A, B and C can be simple chemical elements or alloys) so that targets of the magnetrons (2) are located at the same distance from an exit orifice (5) of the device (1) by means of a shuttle (6). The positioning of the magnetrons (2), which in this case are three, but whose number can be increased or decreased depending on the applications, is performed individually thanks to individual positioning means (3) of each magnetron (2 ). Each magnetron (2) also has an independent power supply and an independent argon input. The argon fluxes and powers that are applied to each magnetron (2) by the power supply are therefore independent for each magnetron (2). In this way, ion fl ows of the materials A, B, C that are generated in the device (1) are controlled. In an aggregation zone (4) of the device (1) ions of materials A, B and C collide to form nanoparticles, whose chemical composition is given by the ion concentrations of materials A, B and C. In other words, the control of the ions fl ow of materials A, B and C generated individually by each magnetron (2) allows the control of the chemical composition of the nanoparticles that form in the aggregation zone (4) of the device (1) connected by a flange to the magnetrons (2). The control of the size of the nanoparticles is achieved thanks to the positioning of the set of magnetrons (2) within the aggregation zone (4) thanks to a transfer (6).

Finally, a vacuum system is used to extract the contents of the chamber, mainly the gases present in it, and thus be able to access the nanoparticles generated and deposited on the substrate.

Example 2

Procedure for the manufacture of onion or core-shell nanoparticles

For the manufacture of nanoparticles of the "core-shell" type, each of the individual positioning means (3) of each magnetron (2) is used to position these at relative distances in a controlled manner. In this case, the magnetrons (2) are positioned so that the targets of the magnetrons (2) are located at different distances from the outlet port (5) of the device (1). To form "core-shell" nanoparticles with the AB structure, being the material A that composes the core (core) of the nanoparticle and material B the one that composes the outer part or crust (shell), the magnetron (2) is positioned ) that generates the ions of the material A greater distance from the outlet (5) of the device (1) than that of the magnetron (2), which generates the ions of the material B. In this configuration, the ions of the material A collide in their path to the outlet orifice (5) of the device (1), thereby forming nanoparticles of material A. By passing through a plasma generated by the magnetron (2) of material B, these nanoparticles are covered with material B, which it is deposited on the core of material A, resulting in the formation of core-shell nanoparticles with the AB structure. The control of the relative positions of the magnetrons (2) and of the ions fluxes of materials A and B generated individually by each magnetron (2) (by means of the powers applied to each magnetron and of the individual argon fl ows) allows select the size of the material cores Ay and the thickness of the material B crusts. This procedure can be extended to manufacture more complex core-shell nanoparticles, with AB-C structures generated by positioning 2 (or more) magnetrons (2) at the positions furthest from the outlet (5) of the device (1), to generate an AB alloy core that is subsequently covered with a crust of material C or an alloy of materials, depending on the number of magnetrons (2) available on the device (1).

Claims (3)

1. Device (1) for manufacturing nanoparticles comprising: -a chamber where an aggregation zone (4) is defined and in which a outlet port (5), -at least one gas inlet to the chamber to generate an arti fi cial atmosphere inside the chamber, -at least a blank of nanoparticle material to be generated, -a gas pumping means connected to the chamber aggregation zone (4) and vacuum chamber managers to control the gas pressures inside them, and characterized in that it comprises: -at least two magnetrons (2) responsible for generating ions of the material blank material, -a single positioning means (3) of each of the magnetrons (2) responsible for individually positioning each magnetron (2) with respect to the exit hole (5), -a transfer (6) responsible for positioning the magnetrons (2) within the aggregation zone (4), -a flange of connection responsible for connecting the magnetrons (2) to the aggregation zone (4), -a separate power supply for each magnetron (2), and -a separate gas inlet for each magnetron (2). 2. Method of manufacturing nanoparticles using the device (1) described in claim 1, characterized in that it comprises the following steps: - introducing at least one gas in the aggregation zone (4), - positioning the magnetrons (2) by the positioner (6) - individually position each of the magnetrons (2) at a distance from the output office (5), and - regulate the power of at least one of the magnetrons (2), - actuate the magnetrons (2 ) to bombard the target material thus generating material ions, and

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maintain the above conditions until the formation of aggregates of the ions generated in the previous phase that form the nanoparticles.

SPANISH OFFICE OF THE PATENTS AND BRAND Application no .: 201030059 SPAIN Date of submission of the application: 19.01.2010 Priority Date: REPORT ON THE STATE OF THE TECHNIQUE 51 Int. Cl.: C23C14 / 35 (2006.01) H01J37 / 34 (2006.01) RELEVANT DOCUMENTS

Category

Documents cited Claims Affected

X

BAI and WANG. High-magnetic-moment core-shell-typeFeCo - Au / Ag nanoparticles. Appl. Phys. Lett. 87, 152502 (2005), DOI: 10.1063 / 1.2089171, ISSN 0003-6951 (04.10.2005). 1-2

TO

US 2005103620 A1 (ZOND INC) 05/19/2005, figure 6; paragraphs [151-153]; claims 1,6-7,23. 1-2

TO

WO 2009149563 A1 (FABLAB INC et al.) 17.12.2009, figure 6; paragraph [47]; claims 19,24. 1-2

TO

JP 2006249506 A (NAT INST FOR MATERIALS SCIENCE) 21.09.2006, figures 1-3. Summary of the WPI database. Recovered from EPOQUE [recovered on 08.06.2011]. one

TO

XU and WANG. , Direct Gas-Phase Synthesis of Heterostructured Nanoparticles through Phase Separation and Surface Segregation. Advanced Materials, 2008, 20: 994–999. doi: 10.1002 / adma.200602895 (12.02.2008).

Category of the documents cited X: of particular relevance Y: of particular relevance combined with other / s of the same category A: reflects the state of the art O: refers to unwritten disclosure P: published between the priority date and the date of priority submission of the application E: previous document, but published after the date of submission of the application

This report has been prepared • for all claims • for claims no:

Date of realization of the report 31.08.2011

Examiner E. Pina Martínez Page 1/4

REPORT OF THE STATE OF THE TECHNIQUE Application number: 201030059 Minimum documentation sought (classification system followed by classification symbols) C23C, H01J Electronic databases consulted during the search (name of the database and, if possible, terms of search used) INVENES, EPODOC, WPI, NPL, XPESP, INSPEC, XPAIP State of the Art Report Page 2/4  WRITTEN OPINION Application number: 201030059 Date of Completion of Written Opinion: 08.31.2011 Statement

Novelty (Art. 6.1 LP 11/1986)

Claims Claims 1-2 IF NOT

Inventive activity (Art. 8.1 LP11 / 1986)

Claims Claims 1-2 IF NOT

The application is considered to comply with the industrial application requirement. This requirement was evaluated during the formal and technical examination phase of the application (Article 31.2 Law 11/1986).  Opinion Base.- This opinion has been made on the basis of the patent application as published. State of the Art Report Page 3/4  WRITTEN OPINION Application number: 201030059 1. Documents considered.- The documents belonging to the state of the art taken into consideration for the realization of this opinion are listed below.

Document

Publication or Identification Number publication date

D01

BAI and WANG. High-magnetic-moment core-shell-type FeCo - Au / Ag nanoparticles. 04.10.2005

D02

US 2005103620 A1 (ZOND INC) 05/19/2005

2. Statement motivated according to articles 29.6 and 29.7 of the Regulations for the execution of Law 11/1986, of March 20, on Patents on novelty and inventive activity; quotes and explanations in support of this statement D01 is considered the prior art document closest to the claimed object. This document would affect the inventive activity of all claims, as will be explained below: Claim 1 Document D01 describes a device that, in the terms used in the application, comprises the following elements (references in brackets refer to D01): Device for manufacturing nanoparticles comprising (see figure 1): -a chamber where an aggregation zone is defined and in which an exit hole is located (Shell Formation) -at least one gas inlet to the chamber to generate an artificial atmosphere inside the chamber (Carrier Gas), -at least one blank of nanoparticle material to be generated (FeCo in D01), -a gas pumping means connected to the aggregation zone and the vacuum chamber responsible for controlling the gas pressures inside them (Pump I) -at least two magnetrons responsible for generating ions of the material blank (Sputtering Targets) The difference between the device described in D01 and the one defined in claim 1 of the application resides in the presence of individual positioning means or magnetron translators, which are not mentioned in D01, although the configuration of the device in D01 implies the previous placement of magnetrons with different targets in different locations of the chamber along the path that the nanoparticles initially evaporated to the exit hole. On the other hand, individual magnetron positioning means are well known in the prior art. As an example, document D02 (para. [151-153], fig. 6) in which a sputtering deposition chamber with several independently operated magnetrons and whose position with respect to the substrate can be varied individually by positioning means can be seen ad hoc. Thus, it is considered that the person skilled in the art, without the exercise of inventive effort, would incorporate individual positioning means into the device described in D01 in order to modify at will the positions of the different magnetrons and motivated by the need to optimize the control of the sputtering conditions, and therefore of the properties of the nanoparticles obtained. As regards the connection flange of the magnetrons and the individual gas supply and input elements of the magnetrons, they are considered common and necessary elements for the independent operation of the mimes. In conclusion, in view of the prior art, claim 1 would not satisfy the requirement of inventive activity as set forth in Art. 8.1 of Patent Law 11/86. Claim 2 The claimed procedure can be found described in document D01, with the exception of the magnetron positioning stage by means of a positioner. However, as has been argued in the foregoing, this stage would not involve the exercise of an inventive effort by an expert in the field who would like to modify the position of the magnetrons, driven by the need for greater control over this parameter. Therefore, it is considered that claim 2 would not satisfy the requirement of inventive activity (Art. 8.1 LP). In conclusion, in view of the prior art, the application would not satisfy the patentability requirements set forth in Art 4.1 LP. State of the Art Report Page 4/4