Method for obtaining nanodimensional ferrite films

FIELD: nanotechnologies.

SUBSTANCE: invention relates to a technology for obtaining nanodimensional films of multiferroics and can be used in production of high-quality magneto-optic information processing and storage devices, magnetic sensors, capacitive electromagnets, magnetoelectric storage elements and non-mutual microwave filters. The method involves manufacture of a target of the specified composition, processing of a monocrystalline substrate with argon ions, spraying of the target onto the substrate with further annealing of the obtained film; with that, a strontium titanate substrate is used; the spraying process is performed onto the substrate heated up to 700-750°C; controlled flow of oxygen ions is supplied to the substrate area, and the obtained films are annealed in oxygen environment during 1.0 hour at the temperature of 500-550°C and standard atmospheric pressure.

EFFECT: invention allows obtaining monocrystalline nanodimensional films of multiferroics with BiFeO3 and RxBi1-xFeO3 composition (where R- Nd, La, Pr in the quantity of 0,1-0,3 form units).

1 tbl, 1 ex

 

The invention relates to a technology for nanoscale films of multiferroic composition BiFeO3and RxBi1-xFeO3and can find application in the production of high-q optical processing devices and information storage, magnetic sensors, capacitive electromagnets, magnetic memory elements, the non-microwave filters and other devices.

The known method of producing nanoscale films of bismuth ferrite by chemical vapor deposition from the vapor phase ORGANOMETALLIC compounds (MOCVD) (see Kartavtseva M. R. Synthesis and properties of epitaxial thin films BiFeO3and solid solutions based on it. Thesis for the academic Art. c.ch.s. M, MSU, 2008. - 24 C.). The disadvantages of the method is receiving a multiphase films, the toxicity of the starting components for human health, the high cost of the method.

Closest to the proposed is a Method of producing nanoscale films of ferrite-garnet containing Bi" (see: patent of Ukraine # 66219. Prokopov A.R., Shaposhnikov A.N., Caramanico AV "Method of producing nanoscale films of ferrite-garnet containing Bi". Bull. No. 24, 2011). The method includes producing a target for a given composition, processing monocrystalline substrate by argon ions, sputtering components of the target on a substrate and annealing in air PR is atmospheric pressure. The disadvantage of this method is the inability to obtain nanoscale films of multiferroic composition BiFeO3and RxBi1-xFeO3(where R=Nd, La, Pr in the amount of 0.1-0.3 formed).

The purpose of the present invention is the obtaining of nanoscale multiferroic films composition BiFeO3and RxBi1-xFeO3(where R=Nd, La, Pr in the amount of 0.1-0.3 formed).

This goal is achieved by the fact that in the proposed method of producing nanoscale ferrite films, including production targets specified composition, processing monocrystalline substrate by argon ions, the sputtering target onto the substrate with further annealing of the films obtained in accordance with the proposed technical solution is used, the substrate of strontium titanate, ion sputtering and heating of the substrate during deposition of a film up to 700-750°C, flow in the area of the substrate of the controlled flow of oxygen and annealing of the obtained films for 1.0 hour in an atmosphere of oxygen at a temperature of 500-550°C under normal atmospheric pressure.

The essence of the proposed method lies in the fact that the use of a heated substrate, flow in the region of the substrate controlled flow of oxygen ions and subsequent annealing of the obtained structures in the atmosphere of oxygen at normal atmospheric pressure allows one to obtain high-quality nanoscale Fe film is Rita compositions BiFeO 3and RxBi1-xFeO3(where R=Nd, La, Pr in the amount of 0.1-0.3 formed). The use of monocrystalline plates of strontium titanate as the substrate allows to obtain single-crystal films of ferrites of the above compounds.

The method is implemented as follows. Made a target of the desired composition (BiFeO3or RxBi1-xFeO3where R=Nd, La, Pr in the amount of 0.1-0.3 formed). Monocrystalline substrate of strontium titanate treated by argon ions of energy of 10-20 eV. In the vacuum chamber reaches a pressure (about 6.5-6.8)·10-4PA and produce with a platinum heater heating the substrate to a temperature of 700-750°C. Next, produce a precipitation of the target material on a substrate by sputtering with argon beam ion source (the current density of the ion beam j=8 to 12 mA/cm2the ion energy E=1-3 Kev). In order to facilitate crystallization of stoichiometric film of bismuth ferrite (pure or substituted) in the region of the substrate supplied by the ion source controlled flow of oxygen ions. The required film thickness is governed by the time of spraying. The resulting structure is placed in a furnace and annealed in oxygen atmosphere at a temperature of 500-550°C at normal atmospheric pressure for one hour.

An example implementation of the method

Using ceramic technology the AI was prepared target BiFeO 3and RxBi1-xFeO3(where R=Nd, La, Pr in an amount of 0.1 to 0.2 formed). The diameter of the target was 100 mm as substrates were used monocrystalline plate-substrate of strontium titanate SrTiO3. The process of obtaining nanoscale films of composition BiFeO3and RxBi1-xFeO3(where R=Nd, La, Pr in an amount of 0.1 to 0.2 formed) was carried out in a vacuum unit, based on the installation of the IOC 3279026. In the vacuum chamber reached pressure (about 6.5-6.8)·10-4PA, and then perform the processing of the substrate by argon ions of energy of 10-20 eV. Next were made with a platinum heater heating the substrate to a temperature of 750°C, followed by deposition of the target material on a substrate by sputtering with argon beam ion source (the current density of the ion beam j=12 mA/cm2the ion energy E=3 Kev). In order to facilitate crystallization of stoichiometric film of bismuth ferrite in the area of the substrate was applied using an ion source controlled flow of oxygen ions. The obtained films were annealed in the kiln yttrium garnets T-1 five-2.983.003 JV oxygen atmosphere at a temperature of 550°C and normal atmospheric pressure. After natural cooling installations for the roasting to room temperature, the obtained film was washed in distilled and Dionysian the th water. Thus were prepared in 5 films of each composition.

The results of x-ray diffraction studies showed that the obtained nano-films are single crystalline.

The table shows the main characteristics of the obtained nano-films of bismuth ferrite.

Table
Properties obtained by the method HAI film multiferroic (substrate SrTiO3; TISM=300K)
№ p/pThe chemical composition of the filmThe film thickness, nmControlled properties
The specific Faraday rotation θF, deg/cm (λ=0,633 µm)The coercive force HWithE
1BiFeO32503 8000,85
2Biof 0.85Laof 0.15FeO32554 0750,65
3Bi0,8La of 0.15FeO32754 1800,75
4Bifor 0.9Laa 0.1FeO32404 9000,78
5Biof 0.85Laof 0.15FeO32455 6000,72
6Bifor 0.9Laa 0.1FeO31956 3500,80
7Biof 0.85Laof 0.15FeO32206 7500,70

Thus, the proposed method has the following distinctive features:

1. Used single-crystal substrate of strontium titanate.

2. Is heated substrate to a temperature of 700-750°C.

3. Used during the spraying process flow in the region of the substrate controlled flow of oxygen ions.

4. The resulting film is annealed in oxygen for 1.0 hour at a temperature of 500-550°C and normal atmospheric pressure.

The use of this profile is part of the signs for the achievement of the results obtained the authors are unknown.

The method of obtaining nanosized ferrite films, including production targets specified composition, processing monocrystalline substrate by argon ions, the sputtering target onto the substrate with further annealing the resulting film, characterized in that the used substrate of strontium titanate, the process of dispersion is heated to a temperature of 700-750°C substrate during the spraying process is supplied in the region of the substrate controlled flow of oxygen ions, and the resulting film is annealed in oxygen atmosphere for 1.0 hour at a temperature of 500-550°C and normal atmospheric pressure.



 

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