阅读说明：本技术 利用离子注入技术制备的二氧化钛晶相异质结构及其方法 (Titanium dioxide crystalline phase heterostructure prepared by ion implantation technology and method thereof ) 是由 马钰洁 于 2019-09-30 设计创作，主要内容包括：本发明公开了一种利用离子注入技术制备的二氧化钛晶相异质结构及其方法,该结构基于金红石二氧化钛单晶块体材料,存在于近表面区域,由不同厚度的锐钛矿结构层(3)和金红石结构层(1)相交错构成的异质结构,其中：所述金红石结构层(1)为保留的原始金红石二氧化钛单晶结构,所述锐钛矿层(3)由高剂量、多能量的离子注入后退火获得。本发明利用多能量离子注入和退火方法可以获得晶格结构较好的单晶异质结构,从而实现高效率的光催化转化；并且,同时实现不同晶相(锐钛矿-金红石)和不同晶面的异质结构,进一步提升光催化效率。(The invention discloses a titanium dioxide crystal phase heterostructure prepared by utilizing an ion implantation technology and a method thereof, the structure is based on a rutile titanium dioxide single crystal block material, exists in a near-surface region, and is a heterostructure formed by intersecting anatase structure layers (3) and rutile structure layers (1) with different thicknesses, wherein: the rutile structure layer (1) is a reserved original rutile titanium dioxide single crystal structure, and the anatase layer (3) is obtained by annealing after high-dose and multi-energy ion implantation. The invention can obtain a single crystal heterostructure with a better lattice structure by utilizing a multi-energy ion implantation and annealing method, thereby realizing high-efficiency photocatalytic conversion; moreover, the heterogeneous structures of different crystal phases (anatase-rutile) and different crystal faces are realized simultaneously, and the photocatalytic efficiency is further improved.)

1. a titanium dioxide crystal phase heterostructure prepared by ion implantation technology, which is characterized in that the heterostructure is formed by interlacing anatase structure layers (3) and rutile structure layers (1) with different thicknesses and is present in the near-surface area of a rutile titanium dioxide single crystal bulk material, wherein:

the rutile structure layer (1) is a reserved original rutile titanium dioxide single crystal structure, and the anatase layer (3) is obtained by annealing after high-dose and multi-energy ion implantation.

2. The crystalline phase heterostructure of titanium dioxide fabricated by ion implantation of claim 1, wherein the high dose is in the range of 10¹⁶～10¹⁷Ions per square centimeter.

3. The crystalline phase heterostructure of titanium dioxide fabricated by ion implantation of claim 1, wherein the multi-energy ions have an energy ranging from 0keV to 300keV and a dose ranging from 10 keV¹⁶～10¹⁷Ions per square centimeter.

4. A method for preparing a titanium dioxide crystalline phase heterostructure by utilizing an ion implantation technology is characterized by comprising the following steps:

step 1, respectively putting the rutile titanium dioxide single crystal block material into ethanol and acetone for ultrasonic cleaning treatment, and then drying the rutile titanium dioxide single crystal block material by using nitrogen;

step 2, implanting multi-energy ions into the rutile titanium dioxide single crystal material, forming amorphous layers at the implantation surface and different depths below the surface, wherein original rutile titanium dioxide single crystal layers which are not influenced by ion implantation are formed between the formed amorphous damage layers;

and step 3, annealing treatment is carried out, the annealing temperature is gradually increased from room temperature, the annealing high temperature range is 200-700 ℃, the total annealing time is 2-6 hours, and the amorphous damaged layer is converted into an anatase structural layer.

5. The method of claim 4, wherein in the step 2, the ions are implanted into the bulk rutile titanium dioxide crystal, the implantation surface is polished and the implantation direction is parallel to the [001] crystal direction of the rutile titanium dioxide.

6. The method of claim 4, wherein the step 2 comprises ion implantation under the following conditions:

the method comprises the following steps that firstly, if the room temperature is selected for ion implantation, the density range of the implanted beam current is required to be 1-4 microamperes/square centimeter so as to reduce the surface damage of the crystal caused by thermal deposition; if low-temperature ion implantation is selected, the ion beam current density is not limited;

secondly, injecting ions with small energy, wherein the formed amorphous damage layer is in a near-surface area, the deeper the injection depth of the ions with larger energy is, the farther the formed amorphous damage layer is away from the surface;

and thirdly, selecting larger dose of implanted ions to cause larger crystal lattice damage and thicker formed damaged layer.

7. The method of claim 4, wherein the annealing process of step 3 comprises annealing the sample to 400 ℃ to form an amorphous damaged layer in the titanium dioxide, starting to transform the amorphous damaged layer into anatase structure, and then gradually increasing the temperature to 700 ℃ at the moment when the amorphous structure of the damaged layer is completely transformed into anatase structure.

8. The method of claim 4, wherein the ions have an energy ranging from 0keV to 300keV and a dose ranging from 10 keV to 10 keV¹⁶～10¹⁷Ions per square centimeter.

Technical Field

The invention relates to the technical field of semiconductor photocatalytic materials, in particular to a titanium dioxide crystalline phase heterostructure and a preparation method thereof.

Background

With the development of the photocatalytic technology, the photocatalytic technology is utilized to solve the problems of energy crisis, environmental pollution and the like, and more attention and recognition are obtained. The improvement of the photocatalytic activity of the photocatalyst is the core of the improvement of the photocatalytic technology. Among numerous semiconductor photocatalysts, titanium dioxide is rapidly a semiconductor photocatalyst with the most practical significance and wide application prospect due to the advantages of low cost, easy preparation, no toxicity, no secondary pollution, strong oxidation-reduction capability, light corrosion resistance, stable chemical properties and the like. However, titanium dioxide as a catalyst has low quantum efficiency due to fast photogenerated electron-hole recombination and no response to visible light. Heterostructures are an effective way to solve this problem. Although there are various methods for manufacturing titanium dioxide heterostructures, such as hydrothermal method for manufacturing heterostructures with different dimensions and different crystal faces, sol-gel method for manufacturing heterostructures with different crystal phases, atomic layer deposition and chemical vapor deposition, the titanium dioxide structures prepared by these growth methods are mostly nanoparticle or nanowire structures, and the integrity of their single crystals cannot be guaranteed, so that their application performance is affected. Compared with the titanium dioxide heterostructure prepared by other epitaxial growth methods, the ion implantation method not only realizes the heterostructure with different crystal faces and different crystal phases staggered, but also can accurately control the proportion of different structures so as to realize the high-efficiency photocatalytic conversion performance. To date, there has been no description of the ion implantation method for achieving titania heterostructure fabrication.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a titanium dioxide crystal phase heterostructure prepared by utilizing an ion implantation technology and a method thereof, wherein a rutile-anatase single crystal phase staggered heterostructure is formed in a near-surface region.

The invention relates to a titanium dioxide crystal phase heterostructure prepared by utilizing an ion implantation technology, which is a heterostructure formed by intersecting anatase structure layers (3) and rutile structure layers (1) with different thicknesses and existing in a near-surface region of a rutile titanium dioxide single crystal block material, wherein:

the rutile structure layer (1) is a reserved original rutile titanium dioxide single crystal structure, and the anatase layer (3) is obtained by annealing after high-dose and multi-energy ion implantation.

The invention relates to a titanium dioxide crystalline phase heterostructure prepared by utilizing an ion implantation technology and a method thereof, wherein the method comprises the following steps:

step 1, respectively putting the rutile titanium dioxide single crystal block material into ethanol and acetone for ultrasonic cleaning treatment, and then drying the rutile titanium dioxide single crystal block material by using nitrogen;

step 2, implanting multi-energy ions into the rutile titanium dioxide single crystal block material, forming amorphous layers at the implantation surface and different depths below the surface, wherein original rutile titanium dioxide single crystal layers which are not influenced by ion implantation are formed between amorphous damage layers;

and step 3, annealing treatment is carried out, the annealing temperature is gradually increased from room temperature, the annealing high temperature range is 200-700 ℃, the total annealing time is 2-6 hours, and the amorphous damaged layer is converted into an anatase structural layer.

Compared with the prior art, the invention has the advantages and positive effects that: the titanium dioxide single crystal heterostructure with a good lattice structure can be obtained by utilizing a multi-energy ion implantation and annealing method, so that high-efficiency photocatalytic conversion is realized; moreover, heterogeneous structures with different crystal phases (anatase-rutile) and different crystal faces can be realized, and the photocatalytic efficiency is further improved. Through a series of ion implantation experiments, implantation conditions for forming an amorphous damaged layer in the rutile titanium dioxide single-crystal material were determined, and through a series of annealing treatments, the conversion of the amorphous structure into the anatase structure was confirmed.

Drawings

FIG. 1 is a schematic view of a crystalline phase heterostructure of titanium dioxide prepared by ion implantation of the present invention, (a) is a schematic view of a first structure, and (b) is a schematic view of a second structure;

FIG. 2 is a schematic diagram of a method for preparing a titanium dioxide crystal phase heterostructure using ion implantation technique according to the present invention;

FIG. 3 is a transmission electron microscope image of an amorphous damage layer formed by ion implantation in an embodiment of the present invention;

FIG. 4 is a Raman scattering plot of an ion implanted titanium dioxide sample after annealing at 400 ℃ in an example of the present invention;

FIG. 5 is a graph showing the change in surface topography of an implanted sample before and after annealing in an embodiment of the present invention.

Reference numerals:

1. rutile layer, 2, amorphous damage layer, 3, anatase layer.

Detailed Description

The technical solution of the present invention is described in detail below with reference to the accompanying drawings and examples.

FIG. 1 is a schematic diagram of a titanium dioxide crystal phase heterostructure prepared by ion implantation. The structure is based on a rutile titanium dioxide single crystal bulk material, exists in a near-surface region, and is a heterostructure formed by intersecting anatase structure layers 3 and rutile structure layers 1 with different thicknesses, wherein: the rutile structure layer 1 is a reserved original rutile titanium dioxide single crystal structure, and the anatase layer 3 is obtained by annealing after high-dose and multi-energy ion implantation.

The first anatase layer 3 covers the surface of the rutile structure layer 1, and the rest anatase structure layers 3 are alternately positioned in the rutile layer 1.

The titanium dioxide layer with the original rutile structure which is not influenced by ion implantation exists between the amorphous damage layers formed by ion implantation with different energies, and the energy span of the implanted ions with different energies determines the thickness of the rutile layer.

FIG. 2 is a schematic flow chart of the present invention for preparing a crystalline phase heterostructure of titanium dioxide by ion implantation. The process specifically comprises the following steps:

step 1, respectively putting the rutile titanium dioxide single crystal block material into ethanol and acetone for ultrasonic cleaning treatment, and then drying the rutile titanium dioxide single crystal block material by using nitrogen;

step 2, ions (light ions or heavy ions) are implanted into the rutile titanium dioxide single crystal block material to form amorphous damage layers on the implantation surface and at different depths below the surface, the energy range of the implanted ions is 0 keV-300 keV, and the dose range of the implanted ions is 1 multiplied by 10¹⁶Ion/square centimeter-10 x 10¹⁶Ions per square centimeter, and a rutile layer (i.e., a rutile titanium dioxide single crystal layer) which is not affected by ion implantation is arranged between the formed amorphous damage layers;

and step 3, annealing treatment is carried out, the annealing temperature is gradually increased from room temperature, the annealing high temperature range is 200-700 ℃, the total annealing time is 2-6 hours, and the amorphous damaged layer is converted into an anatase structural layer.

In the step 2, when ions are implanted into the bulk rutile titanium dioxide crystal, the implantation surface is polished and the implantation direction is parallel to the [001] crystal orientation of the rutile titanium dioxide (ions under the same conditions are implanted into the bulk rutile titanium dioxide crystal along different crystal orientations with different results). This step is also affected by different ion implantation conditions, such as:

(1) if the room-temperature ion implantation is selected, the density range of the implanted beam current is required to be 1-4 microamperes/square centimeter so as to reduce the crystal surface damage caused by thermal deposition; if low temperature ion implantation is selected, the ion beam current density is not limited.

(2) And (3) implanting ions with smaller energy to form an amorphous damaged layer in a near-surface region (within 1 micron below the implanted surface), wherein the deeper the implantation depth of the ions with larger energy, the farther the formed amorphous damaged layer is from the surface. The implantation depths of ions of different energies can be determined by simulation experiments.

(3) If the dose of the ion implantation is selected to be larger, the larger the induced lattice damage, the thicker the damaged layer is formed. Therefore, the conditions such as the ion implantation dosage and the beam current density determine the thickness and the quality of the formed amorphous damaged layer.

The proportion of the amorphous damaged layer and the rutile layer can be accurately adjusted by controlling ion implantation conditions (energy, dosage, beam density, implantation temperature and the like).

In the annealing process of the step 3, the annealing temperature is gradually increased with the room temperature as a starting point. Because different crystalline phases of titanium dioxide can be mutually converted under the action of high-temperature annealing, the specific conversion rule is as follows: in the annealing process of 400-700 ℃, the amorphous structure is converted into an anatase structure; further heating to 700-1100 deg.c to convert anatase structure into rutile structure. Thus, the injected sample is first annealed to 400 ℃ and the amorphous damaged layer formed in the titanium dioxide begins to convert into the anatase structure, and then the temperature is gradually raised up to 700 ℃ at which time the amorphous structure of the damaged layer is completely converted into the anatase structure.

According to different injection conditions, the structure and the area of the formed amorphous damage layer are different, so that the annealing conditions required for converting the amorphous damage layer into an anatase structure are different, and the total annealing time is 2-6 hours.

He ions with low energy of 30keV are mixed at 8X 10¹⁶And 10X 10¹⁶Ion/cm dose condition [001] along]The crystal orientation is injected into the rutile titanium dioxide crystal material at room temperature, and the beam current density of the injected ions is 1 microampere/square centimeter. Under the injection condition, the injected ions and titanium dioxide atoms have cascade collision and cause nuclear energy loss, an amorphous damaged layer with the thickness of about 15nm is formed on the surface of a titanium dioxide crystal, and the structural characteristics of the amorphous damaged layer formed after the ion injection and the structural characteristics of the original rutile layer can be observed through a transmission electron microscope, as shown in fig. 3, which is a transmission electron microscope image of the amorphous damaged layer formed by the ion injection in the embodiment of the invention. Through a series of annealing treatments (400 ℃ -700 ℃), a damaged layer structure formed by multi-energy He ions at different depths is converted from amorphous into anatase, the conversion of the crystal phase is verified through experimental means such as a Raman scattering experiment and an Atomic Force Microscope (AFM), and the experimental results are shown in FIGS. 4 and 5.

As shown in fig. 4, in the raman scattering graph after annealing the ion-implanted titania sample at 400 ℃ in the example of the present invention, the lattice structure characteristic of the ion-implanted titania sample after annealing at 400 ℃ was detected by using the raman scattering method, and the vibration peak Eg corresponding to the anatase structure was observed, confirming that the amorphous structure starts to be converted into the anatase structure after annealing at 400 ℃.

FIG. 5 is a graph showing the surface topography change before and after annealing of the implanted sample in the example of the present invention. And observing the change of the surface topography of the sample before and after annealing through an atomic force microscope, thereby determining the conversion characteristic of the structure. (a) A topography of the surface amorphous structure after ion implantation, (b) columnar particles on the surface become bigger after annealing at 500 ℃, and the topography size conforms to the surface topography characteristic of the anatase structure.

The invention utilizes a multi-energy ion implantation method to manufacture a titanium dioxide crystalline phase heterostructure, and the principle is as follows: high dose (10)¹⁶～10¹⁷Ions/cm), multiple energy ions along [001]The method is characterized in that ions with different energies can form amorphous damage layers at different depths below the injection surface of a sample after being injected into a rutile titanium dioxide crystal material under the condition of a crystal orientation room temperature, and the amorphous damage layers formed in the titanium dioxide sample after being injected with the ions are converted into anatase type structures through annealing treatment at 400-700 ℃ because the high-temperature annealing treatment can promote the different crystals of the titanium dioxide to be converted, and original rutile layers are reserved among different damage layers, so that the anatase-rutile different crystal phase staggered heterostructure is realized in the near-surface area of the titanium dioxide.