CN102503559B

CN102503559B - Method for preparing lanthanum cuprate (La2CuO4) film by using liquid-phase self-assembly method

Info

Publication number: CN102503559B
Application number: CN 201110375952
Authority: CN
Inventors: 黄剑锋; 李意峰; 李碧; 曹丽云; 吴建鹏
Original assignee: Shaanxi University of Science and Technology
Current assignee: Shaanxi University of Science and Technology
Priority date: 2011-11-23
Filing date: 2011-11-23
Publication date: 2013-08-14
Anticipated expiration: 2031-11-23
Also published as: CN102503559A

Abstract

The invention relates to a method for preparing a lanthanum cuprate (La2CuO4) film by using a liquid-phase self-assembly method. The method comprises the following steps of: flushing a silicon substrate by using nitric acid, sequentially putting the silicon substrate in beakers containing acetone and ethanol, respectively cleaning by an ultrasonic cleaner, flushing with distilled water, and drying to obtain a substrate A; irradiating the substrate A in an ultraviolet irradiation instrument, then, putting the substrate A in a mixed solution of octadecyl trichlorosilane and toluol, cleaning by using acetone, blow-drying by using N2, putting the substrate A in the ultraviolet irradiation instrument again, and irradiating with ultraviolet to obtain a substrate B; mixing lanthanum nitrate, copper nitrate and citric acid to obtain a solution, adding glacial acetic acid in the solution to obtain a solution C, and vertically standing the substrate B in the solution C for constant-temperature deposition; and cleaning the deposited substrate by using distilled water, drying, then, putting the substrate in a muffle furnace, and calcining to obtain the La2CuO4 film. According to the method, as the liquid-phase self-assembly method is adopted to prepare the La2CuO4 film, the prepared La2CuO4 film is smaller in grain size and contains no impurity, and the method has the advantages of easily controlled reaction process, lower requirements on equipment and simplicity in operation.

Description

The liquid phase self-assembly method prepares copper acid lanthanum (La 2CuO 4) method of film

Technical field

The present invention relates to a kind of La ₂CuO ₄The preparation method of film is specifically related to a kind of liquid phase self-assembly method and prepares La ₂CuO ₄The method of film.Be a kind of can preparing evenly, densification, the preparation method of the film that low defective and intensity are high.

Background technology

Along with the discovery of the above superconductor of fast development, the especially liquid nitrogen temperature of high-temperature superconductor research, opened convenience for the widespread use of superconductor, this also impels the develop rapidly of oxide superconductor thin film physics and technology.With regard to fundamental research, in thin-film material, because lattice mismatch and in film, produce stress (strain) between film and the substrate, and make the character of thin-film material be different from the character of body material.The physical meaning that fully understands these performances is very necessary for disclosing superconduction mechanism, at this on the one hand, because La ₂CuO ₄System structure and Chemical Composition are simple, and the scope of can mixing is wide, La ₂CuO ₄System is research superconduction mechanism desirable material.

Simultaneously, La ₂CuO ₄Be perovskite-like type (A ₂BO ₄) composite oxides, it compares ABO ₃The type oxide compound is many AO halite layer.Its existence makes the BO in the layer ₆The octahedra distortion, thus in bigger elastic range, make Stability Analysis of Structures.Owing to itself be a kind of nonstoichiometric compound, may exist A position ion vacancy and oxygen room in the structure, make it have gas sensing property, can be used as gas sensor, thereby paid attention to widely.

At present, about preparation La ₂CuO ₄The report of film is less, Wang Chunchang [Wang Chunchang.Oxygen Intercalation and Related Properties of La ₂CuO ₄Bulk Samples[D]. Beijing: Tsing-Hua University, 2004.] adopt pulsed laser deposition (PLD), with LaAlO ₃Be substrate, prepare La ₂CuO ₄Film, but this method equipment requirements height, complex process is difficult to the high-quality epitaxial film of preparation.

Summary of the invention

The object of the present invention is to provide a kind of not only preparation cost low, and simple to operate, the high-purity La of high quality that reaction time is short ₂CuO ₄The liquid phase self-assembly preparation method thereof of film.

For achieving the above object, the technical solution used in the present invention is:

1) cleaning of substrate:

The silicon substrate of well cutting is washed with nitric acid, puts into the beaker that fills acetone, ethanol then successively, clean with ultrasonic cleaner respectively, again with behind the distilled water flushing, in 50 ℃～100 ℃ air dry oven, dry substrate A;

2) OTS plated film:

The substrate A of oven dry is placed on 20min～40min in the mixing solutions of octadecyl trichlorosilane (OTS) and toluene shine 20min～120min in the uviolizing instrument after, takes out the back and clean with acetone, use N then ₂Dry up, put into the uviolizing instrument again, get substrate B with uviolizing 15min～50min;

Wherein the mixing solutions of octadecyl trichlorosilane (OTS) and toluene is octadecyl trichlorosilane (OTS): the volume ratio of toluene=1: 99;

3) depositing of thin film

With analytically pure lanthanum nitrate (La (NO ₃) ₃6H ₂O), cupric nitrate (Cu (NO ₃) ₃3H ₂O), citric acid (C ₆H ₈O ₇H ₂O) by 2: 1: the mol ratio of (0.4～2.8) is mixed with the La (NO of 50ml～80ml ₃) ₃Concentration is the solution of 0.5-2mol/L, and the Glacial acetic acid that adds 0.5ml～4ml again in this solution gets solution C, and substrate B is vertically stood in the solution C, after sealing with preservative film, is placed in the loft drier, in 50 ℃～80 ℃ constant temperature depositions;

4) calcining of film

The substrate that deposition is good cleans with distilled water, after the drying, puts into retort furnace, at 450 ℃～800 ℃ calcining 1h～7h down, cools to room temperature with the temperature rise rate of 3 ℃/min～5 ℃/min with the furnace, namely gets La ₂CuO ₄Film.

The present invention adopts the liquid phase self-assembly method to prepare La ₂CuO ₄Film, because self-assembled monolayer is that organic molecule is in solution, spontaneously be adsorbed on formed ultra-thin organic membrane on the solid substrate securely by chemical bond, so it has the spontaneous formation of original position, becomes characteristics such as the key high-sequential is arranged, defective is few, bonding force is strong.It is controlled that the inorganic thin film that deposits at self-assembled monolayer has the densification of structure homogeneous, thickness and form, the La that makes ₂CuO ₄The film grain-size is less, and free from foreign meter, and reaction process be easy to control, equipment requirements is low, and is simple to operate.

Description of drawings

Fig. 1 is the prepared La of embodiment 1 ₂CuO ₄The X-ray diffraction of film (XRD) collection of illustrative plates.

Fig. 2 is the prepared La of embodiment 1 ₂CuO ₄The metallography microscope of film (OM) photo.

Embodiment

Below in conjunction with drawings and Examples the present invention is described in further detail.

Embodiment 1:

1) cleaning of substrate:

The silicon substrate of well cutting is washed with nitric acid, puts into the beaker that fills acetone, ethanol then successively, clean with ultrasonic cleaner respectively, again with behind the distilled water flushing, in 70 ℃ air dry oven, dry substrate A;

2) OTS plated film:

The substrate A of oven dry shine 30min in the mixing solutions that is placed on octadecyl trichlorosilane (OTS) and toluene behind the 30min in the uviolizing instrument, take out the back with the acetone cleaning, use N then ₂Dry up, put into the uviolizing instrument again, get substrate B with uviolizing 25min;

3) depositing of thin film

With analytically pure lanthanum nitrate (La (NO ₃) ₃6H ₂O), cupric nitrate (Cu (NO ₃) ₃3H ₂O), citric acid (C ₆H ₈O ₇H ₂O) be mixed with the La (NO of 60ml by 2: 1: 1.5 mol ratio ₃) ₃Concentration is the solution of 1mol/L, and the Glacial acetic acid that adds 1ml again in this solution gets solution C, and substrate B is vertically stood in the solution C, after sealing with preservative film, is placed in the loft drier, in 60 ℃ of constant temperature depositions;

4) calcining of film

The substrate that deposition is good cleans with distilled water, after the drying, puts into retort furnace, calcines 1.5h with the temperature rise rate of 4 ℃/min down at 600 ℃, cools to room temperature with the furnace, namely gets La ₂CuO ₄Film.

Prepared film is the La of single phase as seen from Figure 1 ₂CuO ₄, as seen from Figure 2, film is comparatively fine and close smooth, and hole is less.

Embodiment 2:

1) cleaning of substrate:

The silicon substrate of well cutting is washed with nitric acid, puts into the beaker that fills acetone, ethanol then successively, clean with ultrasonic cleaner respectively, again with behind the distilled water flushing, in 50 ℃ air dry oven, dry substrate A;

2) OTS plated film:

The substrate A of oven dry shine 20min in the mixing solutions that is placed on octadecyl trichlorosilane (OTS) and toluene behind the 120min in the uviolizing instrument, take out the back with the acetone cleaning, use N then ₂Dry up, put into the uviolizing instrument again, get substrate B with uviolizing 35min;

3) depositing of thin film

With analytically pure lanthanum nitrate (La (NO ₃) ₃6H ₂O), cupric nitrate (Cu (NO ₃) ₃3H ₂O), citric acid (C ₆H ₈O ₇H ₂O) be mixed with the La (NO of 50ml by 2: 1: 0.4 mol ratio ₃) ₃Concentration is the solution of 0.5mol/L, and the Glacial acetic acid that adds 2ml again in this solution gets solution C, and substrate B is vertically stood in the solution C, after sealing with preservative film, is placed in the loft drier, in 80 ℃ of constant temperature depositions;

4) calcining of film

The substrate that deposition is good cleans with distilled water, after the drying, puts into retort furnace, calcines 1h with the temperature rise rate of 3 ℃/min down at 800 ℃, cools to room temperature with the furnace, namely gets La ₂CuO ₄Film.

Embodiment 3:

1) cleaning of substrate:

The silicon substrate of well cutting is washed with nitric acid, puts into the beaker that fills acetone, ethanol then successively, clean with ultrasonic cleaner respectively, again with behind the distilled water flushing, in 100 ℃ air dry oven, dry substrate A;

2) OTS plated film:

The substrate A of oven dry shine 40min in the mixing solutions that is placed on octadecyl trichlorosilane (OTS) and toluene behind the 20min in the uviolizing instrument, take out the back with the acetone cleaning, use N then ₂Dry up, put into the uviolizing instrument again, get substrate B with uviolizing 50min;

3) depositing of thin film

With analytically pure lanthanum nitrate (La (NO ₃) ₃6H ₂O), cupric nitrate (Cu (NO ₃) ₃3H ₂O), citric acid (C ₆H ₈O ₇H ₂O) be mixed with the La (NO of 80ml by 2: 1: 2.2 mol ratio ₃) ₃Concentration is the solution of 1.5mol/L, and the Glacial acetic acid that adds 4ml again in this solution gets solution C, and substrate B is vertically stood in the solution C, after sealing with preservative film, is placed in the loft drier, in 50 ℃ of constant temperature depositions;

4) calcining of film

The substrate that deposition is good cleans with distilled water, after the drying, puts into retort furnace, calcines 7h with the temperature rise rate of 5 ℃/min down at 450 ℃, cools to room temperature with the furnace, namely gets La ₂CuO ₄Film.

Embodiment 4:

1) cleaning of substrate:

The silicon substrate of well cutting is washed with nitric acid, puts into the beaker that fills acetone, ethanol then successively, clean with ultrasonic cleaner respectively, again with behind the distilled water flushing, in 80 ℃ air dry oven, dry substrate A;

2) OTS plated film:

The substrate A of oven dry shine 30min in the mixing solutions that is placed on octadecyl trichlorosilane (OTS) and toluene behind the 80min in the uviolizing instrument, take out the back with the acetone cleaning, use N then ₂Dry up, put into the uviolizing instrument again, get substrate B with uviolizing 15min;

3) depositing of thin film

With analytically pure lanthanum nitrate (La (NO ₃) ₃6H ₂O), cupric nitrate (Cu (NO ₃) ₃3H ₂O), citric acid (C ₆H ₈O ₇H ₂O) be mixed with the La (NO of 70ml by 2: 1: 2.8 mol ratio ₃) ₃Concentration is the solution of 2mol/L, and the Glacial acetic acid that adds 0.5ml again in this solution gets solution C, and substrate B is vertically stood in the solution C, after sealing with preservative film, is placed in the loft drier, in 70 ℃ of constant temperature depositions;

4) calcining of film

The substrate that deposition is good cleans with distilled water, after the drying, puts into retort furnace, calcines 5h with the temperature rise rate of 3 ℃/min down at 550 ℃, cools to room temperature with the furnace, namely gets La ₂CuO ₄Film.

Claims

1. the liquid phase self-assembly method prepares copper acid lanthanum (La ₂CuO ₄) method of film, it is characterized in that:

1) cleaning of substrate:

The silicon substrate of well cutting is washed with nitric acid, puts into the beaker that fills acetone, ethanol then successively, clean with ultrasonic cleaner respectively, again with behind the distilled water flushing, in 50 ℃ ~ 100 ℃ air dry oven, dry substrate A;

2) OTS plated film:

The substrate A of oven dry is placed on 20min ~ 40min in the mixing solutions of octadecyl trichlorosilane (OTS) and toluene shine 20min ~ 120min in the uviolizing instrument after, takes out the back and clean with acetone, use N then ₂Dry up, put into the uviolizing instrument again, get substrate B with uviolizing 15min ~ 50min;

Wherein octadecyl trichlorosilane (OTS) is octadecyl trichlorosilane (OTS) with the mixing solutions of toluene: the volume ratio of toluene=1:99;

3) depositing of thin film

With analytically pure lanthanum nitrate, cupric nitrate, citric acid is by 2:1:(0.4 ~ 2.8) mol ratio be mixed with the La (NO of 50ml ~ 80ml ₃) ₃Concentration is the solution of 0.5 ~ 2mol/L, and the Glacial acetic acid that adds 0.5ml ~ 4ml again in this solution gets solution C, and substrate B is vertically stood in the solution C, after sealing with preservative film, is placed in the loft drier, in 50 ℃ ~ 80 ℃ constant temperature depositions;

4) calcining of film

The substrate that deposition is good cleans with distilled water, after the drying, puts into retort furnace, at 450 ℃ ~ 800 ℃ calcining 1h ~ 7h down, cools to room temperature with the temperature rise rate of 3 ℃/min ~ 5 ℃/min with the furnace, namely gets La ₂CuO ₄Film.