阅读说明：本技术 改变单晶钙钛矿氧化物薄膜材料电学性能的方法 (Method for changing electrical property of single crystal perovskite oxide thin film material ) 是由 黄河意 葛琛 金奎娟 于 2020-04-24 设计创作，主要内容包括：本发明提供一种改变单晶钙钛矿氧化物薄膜材料电学性能的方法,其包括如下步骤：将金属氢化物与待处理的单晶钙钛矿氧化物薄膜材料置于石英玻璃管的不同位置处,然后将放置有金属氢化物与待处理的单晶钙钛矿氧化物薄膜材料的石英玻璃管抽真空并密封,最后对密封的石英玻璃管进行退火处理,即得到电学性能改变的单晶钙钛矿氧化物薄膜材料。由于本发明的方法采用固固反应改变单晶钙钛矿氧化物薄膜材料的电学性能,因此,本发明的方法既简单又清洁无污染。在本发明的方法中,通过调节退火温度和时间可以控制发生还原反应后的单晶钙钛矿氧化物薄膜材料的电学性能。(The invention provides a method for changing the electrical property of a single crystal perovskite oxide thin film material, which comprises the following steps: placing the metal hydride and the single crystal perovskite oxide thin film material to be processed at different positions of a quartz glass tube, then vacuumizing and sealing the quartz glass tube in which the metal hydride and the single crystal perovskite oxide thin film material to be processed are placed, and finally annealing the sealed quartz glass tube to obtain the single crystal perovskite oxide thin film material with changed electrical properties. The method of the invention adopts solid-solid reaction to change the electrical property of the single crystal perovskite oxide thin film material, so the method of the invention is simple, clean and pollution-free. In the method of the present invention, the electrical properties of the single crystal perovskite oxide thin film material after the reduction reaction occurs can be controlled by adjusting the annealing temperature and time.)

1. A method of altering the electrical properties of a single crystal perovskite oxide thin film material comprising the steps of:

placing the metal hydride and the single crystal perovskite oxide thin film material to be processed at different positions of a quartz glass tube, then vacuumizing and sealing the quartz glass tube in which the metal hydride and the single crystal perovskite oxide thin film material to be processed are placed, and finally annealing the sealed quartz glass tube to obtain the single crystal perovskite oxide thin film material with changed electrical properties.

2. The method of claim 1, wherein the metal hydride is selected from one or more of calcium hydride, sodium hydride, and magnesium hydride.

3. The method of claim 1, wherein the single crystal perovskite oxide thin film material is a strontium-doped nickelate perovskite oxide thin film material.

4. The method of claim 1, wherein the single crystal perovskite oxide thin film material is a strontium-doped neodymium nickelate perovskite oxide thin film material.

5. The method of claim 1, wherein the single crystal perovskite oxide thin film material has a chemical formula of Nd_0.8Sr_0.2NiO₃。

6. The method according to claim 1, wherein the ratio of the amount of the metal hydride to the single crystalline perovskite oxide thin film material to be treated is: 1mm²4-20mg of metal hydride is used as the thin film material.

7. The method according to claim 1, wherein the step of evacuating the quartz glass tube with the metal hydride and the single crystal perovskite oxide thin film material to be treated is performed by evacuating the quartz glass tube to a degree of vacuum of 10^-3Pa-10^{- 6}Pa is carried out.

8. The method of claim 1, wherein the annealing is performed under the following conditions: the annealing temperature is 280-340 ℃, and the annealing time is 2-6h, preferably 6 h.

9. The method according to claim 1, wherein the single crystal perovskite oxide thin film material is prepared by molecular beam epitaxy, pulsed laser deposition or magnetron sputtering.

10. The method of claim 1, wherein the placing the metal hydride in the quartz glass tube is performed in a glove box.

Technical Field

The invention belongs to the field of materials. In particular, the invention relates to a method for changing the electrical properties of a single crystal perovskite oxide thin film material.

Background

In general, the electrical properties of the epitaxial single crystal thin film oxide can be changed by doping cations into the material, or by changing the growth filmThe thickness of the film. These methods all need to be performed during the growth process. For regulating and controlling the existing prepared single crystal perovskite oxide thin film material, the method can be realized by adopting the ultra-high vacuum degree equipment for heating and annealing, or putting the single crystal thin film oxide into specific reducing gas for annealing so as to change the valence state of chemical elements and the content of oxygen vacancies in the single crystal thin film oxide. For example, Jeen, h.; choi, W.S.reversible redox reactions in an epitaxially stabilized SrCoO (x) oxyden span.Nat Mater 2013,12(11),1057-63 discloses perovskite SrCoO_3-X(x-0-2) to perovskite SrCoO_2.5Structural phase changes and concomitant transition from metallic to insulating phases. These prior art methods are cumbersome and complicated, and even after-treatment, they may cause unnecessary contamination.

Based on this, a new method capable of greatly reducing the complexity of operation and environmental pollution is needed to change the electrical properties of the prepared single crystal perovskite oxide thin film material.

Disclosure of Invention

The invention aims to provide a simple, clean and pollution-free method for changing the electrical properties of a single crystal perovskite oxide thin film material.

The above object of the present invention is achieved by the following means.

The invention provides a method for changing the electrical property of a single crystal perovskite oxide thin film material, which comprises the following steps:

placing the metal hydride and the single crystal perovskite oxide thin film material to be processed at different positions of a quartz glass tube, then vacuumizing and sealing the quartz glass tube in which the metal hydride and the single crystal perovskite oxide thin film material to be processed are placed, and finally annealing the sealed quartz glass tube to obtain the single crystal perovskite oxide thin film material with changed electrical properties.

Preferably, in the method of the present invention, the metal hydride is selected from one or more of calcium hydride, sodium hydride and magnesium hydride.

Preferably, in the method of the present invention, the single crystal perovskite oxide thin film material is a strontium-doped nickelate perovskite oxide thin film material.

Preferably, in the method of the present invention, the single crystal perovskite oxide thin film material is a strontium-doped neodymium nickelate perovskite oxide thin film material.

Preferably, in the method of the present invention, the chemical formula of the single crystal perovskite oxide thin film material is Nd_0.8Sr_0.2NiO₃。

Preferably, in the method of the present invention, the ratio of the metal hydride to the single crystal perovskite oxide thin film material to be treated is: 1mm²4-20mg of metal hydride is used as the thin film material.

Preferably, in the method of the present invention, the quartz glass tube on which the metal hydride and the single crystal perovskite oxide thin film material to be treated are placed is evacuated by evacuating the quartz glass tube to a degree of vacuum of 10^-3Pa-10^-6Pa is carried out.

Preferably, in the method of the present invention, the annealing treatment is performed under the following conditions: the annealing temperature is 280-400 ℃, and the annealing time is 2-6h, preferably 6 h.

Preferably, in the method of the present invention, the single crystal perovskite oxide thin film material is prepared by molecular beam epitaxy, pulsed laser deposition or magnetron sputtering.

Preferably, in the method of the present invention, the placing of the metal hydride into the quartz glass tube is performed in a glove box.

In a specific embodiment of the present invention, the size of the quartz glass tube is not particularly limited, and the quartz glass tube may contain a metal hydride and a single crystal perovskite oxide thin film material placed therein. Preferably, the length of the quartz glass tube is 100-200mm, and the inner diameter of the quartz glass tube is 5-10 mm.

In the method of the present invention, since the calcium hydride material is easily decomposed into hydrogen and calcium simple substance by heating, the hydrogen can be used to reduce the oxide, so that the metal element with multiple valence states can easily evolve from high valence state to low valence state, and the oxygen content in the oxide will be reduced.

The invention has the following beneficial effects:

the method of the invention adopts solid-solid reaction to change the electrical property of the single crystal perovskite oxide thin film material, so the method of the invention is simple, clean and pollution-free. In the method of the present invention, the electrical properties of the single crystal perovskite oxide thin film material after the reduction reaction occurs can be controlled by adjusting the annealing temperature and time.

The single crystal perovskite oxide thin film material with changed electrical properties obtained by the method can be used as a base material of different semiconductor devices, and provides a good material base for the application of advanced electronic devices.

Drawings

Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:

FIG. 1 is a schematic view of an apparatus for modifying electrical properties according to one embodiment of the present invention;

FIG. 2 is a graph showing the change of resistance with temperature of a single crystal perovskite oxide thin film material (after reduction reaction) with electric properties shifted in examples 1 to 4 of the present invention;

FIG. 3 is an X-ray diffraction pattern of a single crystal perovskite oxide thin film material (after reduction reaction) with transformed electrical properties in examples 1 to 4 of the present invention;

FIG. 4 shows the X-ray absorption spectra of nickel in the sample prepared in example 4 of the present invention and the original sample;

reference numerals:

1 muffle furnace

2 glass quartz tube

3 metal hydrides

4 single crystal perovskite oxide thin film material.

Detailed Description

The present invention is described in further detail below with reference to specific embodiments, which are given for the purpose of illustration only and are not intended to limit the scope of the invention.

Example 1

Strontium-doped neodymium nickelate perovskite single crystal thin film material Nd_0.8Sr_0.2NiO₃The preparation of (1):

using NiO and Nd₂O₃And SrCO₃The powder is prepared from the following components in a molar ratio of 5: 2: 1 charging and sintering to Nd_0.8Sr_0.2NiO₃The target of (1). Selecting SrTiO₃As a substrate. Adopting a laser pulse deposition method, bombarding the target material by using pulse laser to form plasma, wherein the frequency of the pulse laser is 2Hz, and the laser energy density is 1.5J/cm². In SrTiO₃Intermediate products are formed after deposition on the substrate. The deposition conditions were: the deposition temperature is 550 ℃ and the pressure of the deposition oxygen is 25 Pa. In FIG. 2 is shown the SrTiO₃(001) Nd with good crystal quality grows on the substrate_0.8Sr_0.2NiO₃Thin film material, denoted as original sample, having a lattice constant of

Calcium hydride reduction treatment:

in a glove box 25mm²Nd_0.8Sr_0.2NiO₃Mixing the film material with 100mg calcium hydride powder, placing into heat-resistant quartz glass, and vacuumizing to 10%^-4Pa, and annealing in a muffle furnace shown in fig. 1, wherein the annealing temperature is 280 ℃ and the annealing time is 6 hours, and then the prepared sample 1 is stored in vacuum.

Example 2

Except that Nd_0.8Sr_0.2NiO₃The annealing temperature of the film material is not 300 ℃, and the other operation conditions are the same as the example 1. The prepared sample 2 was stored under vacuum.

Example 3

Except that Nd_0.8Sr_0.2NiO₃The annealing temperature of the film material is not 320 ℃, and the other operation conditions are the same as the example 1. Will make intoThe prepared sample 3 was stored under vacuum.

Example 4

Except that Nd_0.8Sr_0.2NiO₃The annealing temperature of the film material is not 340 ℃, and the other operation conditions are the same as the example 1. The prepared sample 4 was stored under vacuum.

Example 5

The samples 1, 2, 3 and 4 and the original sample are subjected to an electrical transport performance test, and the change of the resistance value of the sample along with the temperature can be measured.

FIG. 2 shows that the original sample resistance exhibits metallic behavior with temperature change, the sample 1 resistance becomes insulating with temperature change, and the resistance value at 300K is 3 orders of magnitude greater than the original sample value; the resistance of the sample 2 still presents insulation property along with the temperature change, but the resistance value is 1 order of magnitude lower than that of the sample 1 under 300K; the resistance characteristic of the sample 3 is converted into the metal characteristic, and the resistance value is 1 order of magnitude lower than that of the sample 2 at 300K; the sample 4 resistance characteristic is a metallic characteristic, and the resistance magnitude is 1 magnitude lower than the original at 300K.

From the electrical transport properties, it can be seen that the function of changing the resistive properties of the sample can be achieved by adjusting the processing temperature, and the transition from metallic to insulating to metallic can be achieved. Provides a technical method for realizing materials with different electrical characteristics.

Example 6

The samples 1, 2, 3 and 4 and the original sample are subjected to X-ray diffraction characterization operation, and macroscopic changes of the sample structure can be measured.

FIG. 3 is an X-ray diffraction pattern of a single crystal perovskite oxide thin film material after reduction reaction in examples 1 to 4 of the present invention. Nd after pulse deposition_0.8Sr_0.2NiO₃The sample is marked as an original sample, and the C-axis lattice constant is calculated by X-ray diffraction

FIG. 3 shows the C-axis lattice constant expansion of sample 1, becomingThe C-axis lattice constant of sample 2 expands to becomeThe X-ray diffraction peak of sample 3 disappeared relative to the original peak; the X-ray diffraction peak of the sample 4 is shifted to the right with respect to the original position, and the C-axis lattice constant becomesIt can be concluded that the lattice parameter of the C-axis increases with the annealing temperature of the hydrogenation, and that a new perovskite structure different from the previous one appears when the lattice begins to collapse after the lattice changes its original form after reaching a certain temperature.

Fig. 4 shows the change of the nickel edging of the original sample and sample 4 after the reduction treatment, which is subjected to the X-ray absorption spectrum test: l of Ni₃The absorption edge moves to the left, which shows that the valence state of Ni is reduced after the solid-phase reaction, and the purpose of reducing the material is achieved.

In summary, by controlling the temperature of the solid-phase reaction annealing from 280 ℃ to 340 ℃, fig. 2 and 3 show that the conversion in the peak position of the XRD structure of the sample and the conversion in the electrical properties meet the corresponding relationship. Specifically, the XRD peak position of the thin film material moves leftwards during the process from 280 ℃ to 300 ℃, and meanwhile, the sample is transited from a metal phase to an insulating phase, and the resistance is further increased; the XRD peak position of the thin film material in the second transformation process from 320 c to 340 c is shifted to the opposite right direction, and at the same time, the electrical properties are gradually transformed from the insulating phase to the metallic phase and the resistance is further decreased.