CN103833353A - Praseodymium- iron- co-doped strontium titanate multiferroic film and preparation process thereof - Google Patents

Abstract

A praseodymium- iron- co-doped strontium titanate multiferroic film and a preparation process thereof are disclosed. The strontium titanate film comprises a material the formula of which is Sr[1-x]PrxTi[1-y]FeyO3, wherein 0.025<=x<=0.075, and 0.05<=y<=0.3. The preparation process includes: weighing strontium acetate, praseodymium oxide, butyl titanate and ferric nitrate according to the molar ratio in the formula, dissolving the strontium acetate and the butyl titanate with acetic acid and ethylene glycol monomethyl ether in two steps, dissolving the ferric nitrate with the ethylene glycol monomethyl ether, reacting concentrated nitric acid with the praseodymium oxide, mixing to form a solution C having a concentration of 0.2 mol/L, whirl-coating the solution C in a whirl coating machine, drying and performing thermal decomposition until the film thickness reaches 300 nm, and annealing to obtain the Sr[1-x]PrxTi[1-y]FeyO3 film. Ferroelectricity and magnetism of strontium titanate, which are induced by praseodymium- iron- co-doping, occur around the room temperature. Preparation of a novel single-phase multiferroic material is achieved.

Description

Strontium titanate multiferroic film and the preparation technology thereof of a kind of praseodymium, iron codoped

Technical field

The present invention relates to the preparation of multiferroic film in materials science field, specifically strontium titanate multiferroic film and the preparation technology thereof of a kind of praseodymium, iron codoped.

Background technology

Single-phase multi-ferroic material refers to the single-phase compound that simultaneously shows ferroelectricity and magnetic.Because various iron is in together in an individual system, between them, unavoidably will interact, thereby can realize the mutual regulation and control between difference in functionality, there is abundant physical background and huge application prospect, therefore become one of focus of Condensed Matter Physics research field recent years.

Current most material only just shows coexisting of ferroelectricity and magnetic under utmost point low temperature, is mainly some Mn oxides, for example: BiMnO ₃, YMnO ₃and HoMnO ₃all below 100K, and because synthetic difficulty, preparation cost are high, need the condition restriction such as High Temperature High Pressure, also has certain distance from practical application Deng, these material magnetic transition temperature.In all single phase multi-iron materials, BiFeO ₃be one of material that is hopeful to be applied most, its major advantage is to have very high ferroelectrie Curie temperature and antiferromagnetic transition temperature, shows the material of ferroelectricity and magnetic when being almost unique so far more than room temperature.But it also exists synthetic difficult problem, and appraise at the current rate with non-stoichiometric and have the reasons such as various dephasigns, BiFeO because Bi volatilization in sample causes Fe ₃have very large leakage current, this makes BiFeO ₃excellent performance particularly ferroelectric hysteresis loop is difficult to present.Therefore, obtaining a kind of preparation technology and simply and at room temperature have the single-phase multi-ferroic material of superperformance, is still problem demanding prompt solution.

Summary of the invention

The object of the invention is to solve low, the synthetic difficulty of existing single-phase multi-ferroic material transformation temperature and high in cost of production problem, strontium titanate multiferroic film and the preparation technology thereof of a kind of praseodymium, iron codoped are provided, preparation technology is simple, and the strontium titanate multiferroic film of preparation can at room temperature can show ferroelectricity and magnetic.

The technical scheme that the present invention adopted is for achieving the above object: the strontium titanate multiferroic film of a kind of praseodymium, iron codoped is Sr by molecular formula _1-xpr _xti _1-yfe _yo ₃material composition, wherein, the span of x is 0.025≤x≤0.075, the span of y is 0.05≤y≤0.3.

A preparation technology for the strontium titanate multiferroic film of praseodymium, iron codoped, comprises the following steps:

Step 1, by Sr:Pr:Ti:Fe=(1-x): x:(1-y): the mol ratio of y takes respectively strontium acetate, Praseodymium trioxide, butyl (tetra) titanate and iron nitrate, for subsequent use;

The strontium acetate that step 2, extracting container take step 1 is all dissolved in acetic acid to forming transparent colourless solution, wherein, add the volume of acetic acid and the ratio of strontium acetate gross weight is 4mL:1g, then in solution, add ethylene glycol monomethyl ether, make the volumetric molar concentration of strontium acetate in solution reach 0.6 ~ 0.7mol/L, stir 20 ~ 40min, and then the butyl (tetra) titanate that adds step 1 to take, stir 20 ~ 40min, form solution A, for subsequent use;

The iron nitrate that step 3, another extracting container take step 1 is all dissolved in ethylene glycol monomethyl ether to forming transparent colourless solution, wherein, add the volume of ethylene glycol monomethyl ether and the ratio of iron nitrate gross weight is 1.2mL:1g, after stirring 20 ~ 40min, its mixing solutions is joined in solution A, form solution B, for subsequent use;

It is in 65 ~ 68% concentrated nitric acid that the Praseodymium trioxide that step 4, another extracting container take step 1 is all dissolved in mass percent concentration, wherein, the volume ratio of concentrated nitric acid and acetic acid is 1:3.5, stir after 0.5 ~ 1h, its mixing solutions is joined in solution B, get again appropriate ethylene glycol monomethyl ether difference cleaning step three and the container of step 4, and scavenging solution is poured in solution B, in solution B, add again ethylene glycol monomethyl ether, make the volumetric molar concentration of strontium acetate in solution B reach 0.2mol/L, then stir 6 ~ 8h, filter to obtain solution C, for subsequent use;

Step 5, solution C prepared by step 4 drop on the clean platinum plating silicon substrate being placed in photoresist spinner, and the whirl coating speed that photoresist spinner is set is 3000 ~ 4000 rpm, and the whirl coating time is 25 ~ 35s, makes Sr _1-xpr _xti _1-yfe _yo ₃wet film, by the Sr making _1-xpr _xti _1-yfe _yo ₃wet film is dried after 5min at 200 ℃, carries out thermolysis 5min at 350 ℃, makes Sr _1-xpr _xti _1-yfe _yo ₃dry film, the Sr making _1-xpr _xti _1-yfe _yo ₃on dry film, continue to drip solution C, and repeat successively above-mentioned whirl coating, oven dry and thermal decomposition process, until Sr _1-xpr _xti _1-yfe _yo ₃build reaches 300nm, then in the tube furnace of 700 ~ 750 ℃, the 50 ~ 60min that anneals under nitrogen atmosphere, obtain Sr _1-xpr _xti _1-yfe _yo ₃film.

In the present invention, the purity of strontium acetate is 99.2%, and the purity of metatitanic acid fourth fat is 98%, and Praseodymium trioxide purity is 99.5%, and iron nitrate purity is 99%, and the purity of ethylene glycol monomethyl ether is 99%.

In the present invention, strontium element and praseodymium element mol ratio are: 0.975/0.025 ~ 0.925/0.075; The mol ratio of titanium elements and ferro element is: 0.95/0.05 ~ 0.7/0.3; Due to Sr _1-xpr _xti _1-yfe _yo ₃the characteristic of film is along with the concentration of doped element Pr and Fe is different and different, and in the time that doping content is too low, when the value of x and y is less than normal, strontium titanate is difficult to occur ferroelectricity and magnetic; In the time that doping content is too high, when the value of x is bigger than normal, polarization meeting reduces with the increase of Pr content, and these are different from Pr constituent content, Pr ³⁺/ Pr ⁴⁺the variation of relative proportion relevant.Part radius is the Pr of 0.9 dust ⁴⁺ion can occupy the Pr that radius is 0.68 dust ⁴⁺ion position, the structure cell that caused thus increases, and can compensate Pr ³⁺/ Pr ⁴⁺ion occupies Sr ²⁺reducing of the lattice parameter that position causes, thus polarization suppressed; When the value of y is bigger than normal, iron ion increases, Fe ²⁺and Fe ³⁺between transition of electron meeting cause in sample leakage current to increase, also make thin-film ferroelectric be difficult to occur.

Beneficial effect: (1), the present invention adopt metal-organic decomposition method, induce ferroelectricity and the magnetic of strontium titanate by praseodymium, iron codoped simultaneously, realize a kind of preparation of new single phase multi-iron material, there is simple, the lower-cost feature of preparation technology compared with traditional single phase multi-ferroic material;

(2), ferroelectricity and the magnetic of strontium titanate that the present invention induces appears near room temperature, only can could occur at low temperatures ferroelectricity and Magnetic Phase ratio with traditional single-phase multi-ferroic material simultaneously, have a good application prospect;

(3), the strontium acetate in the present invention, Praseodymium trioxide, metatitanic acid fourth fat and iron nitrate are respectively as the precursor of strontium element, praseodymium element, titanium elements and ferro element, acetic acid, ethylene glycol monomethyl ether and concentrated nitric acid are as solvent, the present invention has provided the adding proportion of each solvent and the step of configuration solution C, this makes acidity, stability and the viscosity etc. of solution C reach optimum regime, thereby improve homogeneity and the density of prepared film phase, reached stabilizing solution and improve the object of film sintered performance.

Accompanying drawing explanation

Fig. 1 is the praseodymium of embodiment 1,2 and 3 preparations, the strontium titanate XRD figure of iron codoped;

Fig. 2 is the ferroelectric hysteresis loop figure measuring under the strontium titanate room temperature of praseodymium, iron codoped of embodiment 1,2 and 3 preparation;

Fig. 3 is the magnetic hysteresis loop figure measuring under the strontium titanate room temperature of praseodymium, iron codoped of embodiment 1,2 and 3 preparation.

Reference numeral: C1 is the sample that embodiment 1 makes, and C2 is the sample that embodiment 2 makes, and C3 is the sample that embodiment 3 makes.

Embodiment

A strontium titanate multiferroic film for praseodymium, iron codoped is Sr by molecular formula _1-xpr _xti _1-yfe _yo ₃material composition, wherein, the span of x is 0.025≤x≤0.075, the span of y is 0.05≤y≤0.3.

Embodiment 1

A preparation technology for the strontium titanate multiferroic film of praseodymium, iron codoped, comprises the following steps:

Step 1, take in molar ratio the strontium acetate of 0.0039078 mol and the Praseodymium trioxide (Pr of 0.0000167 mol ₆o ₁₁), strontium and praseodymium element mol ratio are Sr/Pr=0.975/0.025; Take in molar ratio the metatitanic acid fourth fat of 0.036 mol and the iron nitrate of 0.004 mol, the mol ratio of titanium and ferro element is Ti/Fe=0.9/0.1, for subsequent use;

Step 2, the strontium acetate that step 1 is taken are all dissolved in acetic acid to forming transparent colourless solution, wherein, add the volume of acetic acid and the ratio of strontium acetate gross weight is 4mL:1g, then add ethylene glycol monomethyl ether, make the volumetric molar concentration of strontium acetate in solution reach 0.6mol/L, stir 30min, and then the butyl (tetra) titanate that adds step 1 to take, stir 30min, form solution A, for subsequent use;

Step 3, the iron nitrate that step 1 is taken are all dissolved in ethylene glycol monomethyl ether to forming transparent colourless solution, wherein, add the volume of ethylene glycol monomethyl ether and the ratio of iron nitrate gross weight is 1.2mL:1g, its mixing solutions is joined in solution A after stirring 30min, form solution B, for subsequent use;

Step 4, it is in 65 ~ 68% concentrated nitric acid that the Praseodymium trioxide that step 1 is taken is all dissolved in mass percent concentration, wherein, the volumetric molar concentration of concentrated nitric acid is 16mol/L, the volume ratio of concentrated nitric acid and acetic acid is 1:3.5, stir after 1h, its mixing solutions is joined in solution B, and use respectively ethylene glycol monomethyl ether cleaning step three and the step 4 beaker inwall used of 2mL, spend respectively iron-residues and the praseodymium residue removed on beaker inwall, and scavenging solution is poured in solution B, and then add appropriate ethylene glycol monomethyl ether, make the volumetric molar concentration of strontium acetate in solution reach 0.2mol/L, then stir 8h, filter to obtain precursor aqueous solution C, for subsequent use,

Step 5, precursor aqueous solution C prepared by step 4 drop in clean platinum plating silicon substrate (111) Pt/Ti/SiO being placed in photoresist spinner ₂/ Si is upper, and the whirl coating speed that photoresist spinner is set is 3500 rpm, and the whirl coating time is 30s, makes Sr _0.975pr _0.025ti _0.9fe _0.1o ₃wet film, by the Sr making _0.975pr _0.025ti _0.9fe _0.1o ₃wet film is dried after 5min at 200 ℃, carries out thermolysis 5min at 350 ℃, makes Sr _0.975pr _0.025ti _0.9fe _0.1o ₃dry film, the Sr making _0.975pr _0.025ti _0.9fe _0.1o ₃on dry film, continue to drip precursor aqueous solution C, and repeat successively above-mentioned whirl coating, oven dry and thermal decomposition process, until Sr _0.975pr _0.025ti _0.9fe _0.1o ₃build reaches 300nm, then in the tube furnace of 750 ℃, the 60min that anneals under nitrogen atmosphere, obtain Sr _0.975pr _0.025ti _0.9fe _0.1o ₃film.

Embodiment 2

A preparation technology for the strontium titanate multiferroic film of praseodymium, iron codoped, comprises the following steps:

Step 1, take in molar ratio the strontium acetate of 0.0039078 mol and the Praseodymium trioxide (Pr of 0.0000167 mol ₆o ₁₁), strontium and praseodymium element mol ratio are Sr/Pr=0.975/0.025; Take in molar ratio the metatitanic acid fourth fat of 0.032 mol and the iron nitrate of 0.008 mol, the mol ratio of titanium and ferro element is Ti/Fe=0.8/0.2, for subsequent use;

Step 2, the strontium acetate that step 1 is taken are all dissolved in acetic acid to forming transparent colourless solution, wherein, add the volume of acetic acid and the ratio of strontium acetate gross weight is 4mL:1g, then add ethylene glycol monomethyl ether, make the volumetric molar concentration of strontium acetate in solution reach 0.6mol/L, stir 30min, and then the butyl (tetra) titanate that adds step 1 to take, stir 30min, form solution A, for subsequent use;

Step 3, the iron nitrate that step 1 is taken are all dissolved in ethylene glycol monomethyl ether to forming transparent colourless solution, wherein, add the volume of ethylene glycol monomethyl ether and the ratio of iron nitrate gross weight is 1.2mL:1g, its mixing solutions is joined in solution A after stirring 30min, form solution B, for subsequent use;

Step 4, it is in 65 ~ 68% concentrated nitric acid that the Praseodymium trioxide that step 1 is taken is all dissolved in mass percent concentration, wherein, the volumetric molar concentration of concentrated nitric acid is 16mol/L, the volume ratio of concentrated nitric acid and acetic acid is 1:3.5, stir after 50min, its mixing solutions is joined in solution B, and use respectively ethylene glycol monomethyl ether cleaning step three and the step 4 beaker inwall used of 2mL, spend respectively iron-residues and the praseodymium residue removed on beaker inwall, and scavenging solution is poured in solution B, and then add appropriate ethylene glycol monomethyl ether, make the volumetric molar concentration of strontium acetate in solution reach 0.2mol/L, then stir 7h, filter to obtain precursor aqueous solution C, for subsequent use,

Step 5, precursor aqueous solution C prepared by step 4 drop in clean platinum plating silicon substrate (111) Pt/Ti/SiO being placed in photoresist spinner ₂/ Si is upper, and the whirl coating speed that photoresist spinner is set is 3800 rpm, and the whirl coating time is 25s, makes Sr _0.975pr _0.025ti _0.8fe _0.2o ₃wet film, by the Sr making _0.975pr _0.025ti _0.8fe _0.2o ₃wet film is dried after 5min at 200 ℃, carries out thermolysis 5min at 350 ℃, makes Sr _0.975pr _0.025ti _0.8fe _0.2o ₃dry film, the Sr making _0.975pr _0.025ti _0.8fe _0.2o ₃on dry film, continue to drip precursor aqueous solution C, and repeat successively above-mentioned whirl coating, oven dry and thermal decomposition process, until Sr _0.975pr _0.025ti _0.8fe _0.2o ₃build reaches 300nm, then in the tube furnace of 750 ℃, the 60min that anneals under nitrogen atmosphere, obtain Sr _0.975pr _0.025ti _0.8fe _0.2o ₃film.

Embodiment 3

A preparation technology for the strontium titanate multiferroic film of praseodymium, iron codoped, comprises the following steps:

Step 1, take in molar ratio the strontium acetate of 0.0039078 mol and the Praseodymium trioxide (Pr of 0.0000167 mol ₆o ₁₁), strontium and praseodymium element mol ratio are Sr/Pr=0.975/0.025; Take in molar ratio the metatitanic acid fourth fat of 0.028 mol and the iron nitrate of 0.012 mol, the mol ratio of titanium and ferro element is Ti/Fe=0.7/0.3, for subsequent use;

Step 2, the strontium acetate that step 1 is taken are all dissolved in acetic acid to forming transparent colourless solution, wherein, add the volume of acetic acid and the ratio of strontium acetate gross weight is 4mL:1g, then add ethylene glycol monomethyl ether, stir 35min, and then the butyl (tetra) titanate that adds step 1 to take, 35min stirred, form solution A, for subsequent use;

Step 3, the iron nitrate that step 1 is taken are all dissolved in ethylene glycol monomethyl ether to forming transparent colourless solution, wherein, add the volume of ethylene glycol monomethyl ether and the ratio of iron nitrate gross weight is 1.2mL:1g, its mixing solutions is joined in solution A after stirring 40min, form solution B, for subsequent use;

Step 4, it is in 65 ~ 68% concentrated nitric acid that the Praseodymium trioxide that step 1 is taken is all dissolved in mass percent concentration, wherein, the volumetric molar concentration of concentrated nitric acid is 16mol/L, the volume ratio of concentrated nitric acid and acetic acid is 1:3.5, stir after 50min, its mixing solutions is joined in solution B, and use respectively ethylene glycol monomethyl ether cleaning step three and the step 4 beaker inwall used of 2mL, spend respectively iron-residues and the praseodymium residue removed on beaker inwall, and scavenging solution is poured in solution B, and then add appropriate ethylene glycol monomethyl ether, make the volumetric molar concentration of strontium acetate in solution reach 0.2mol/L, then stir 7h, filter to obtain precursor aqueous solution C, for subsequent use,

Step 5, precursor aqueous solution C prepared by step 4 drop in clean platinum plating silicon substrate (111) Pt/Ti/SiO being placed in photoresist spinner ₂/ Si is upper, and the whirl coating speed that photoresist spinner is set is 3000 rpm, and the whirl coating time is 35s, makes Sr _0.975pr _0.025ti _0.7fe _0.3o ₃wet film, by the Sr making _0.975pr _0.025ti _0.7fe _0.3o ₃wet film is dried after 5min at 200 ℃, carries out thermolysis 5min at 350 ℃, makes Sr _0.975pr _0.025ti _0.7fe _0.3o ₃dry film, the Sr making _0.975pr _0.025ti _0.7fe _0.3o ₃on dry film, continue to drip precursor aqueous solution C, and repeat successively above-mentioned whirl coating, oven dry and thermal decomposition process, until Sr _0.975pr _0.025ti _0.7fe _0.3o ₃build reaches 300nm, then in the tube furnace of 700 ℃, the 60min that anneals under nitrogen atmosphere, obtain Sr _0.975pr _0.025ti _0.7fe _0.3o ₃film.

Fig. 1 to Fig. 3 of the present invention, C1 is the Sr that embodiment 1 makes _0.975pr _0.025ti _0.9fe _0.1o ₃film, C2 is the Sr that embodiment 2 makes _0.975pr _0.025ti _0.8fe _0.2o ₃film, C3 is the Sr that embodiment 3 makes _0.975pr _0.025ti _0.7fe _0.3o ₃film.

Be illustrated in figure 1 the praseodymium of embodiment 1,2 and 3 preparations, the strontium titanate XRD figure of iron codoped, as shown in Figure 1, after doping, the one-tenth of strontium titanate is mutually good; Fig. 2 and Fig. 3 show that strontium titanate film presents certain ferroelectricity and magnetic, the strontium titanate film that each embodiment makes can be cashed out ferroelectricity and magnetic 25 ℃ of room temperatures, but along with the increase of Fe content, ferroelectricity and magnetic weaken gradually, and the strontium titanate film that embodiment 1 and embodiment 2 make is functional; In the time of Ti/Fe=0.7/0.3, ferroelectric hysteresis loop shape gross distortion, this is due to iron ion appraises at the current rate and causes that this sample leakage current increases.Can be shown by Fig. 1 to Fig. 3, praseodymium, iron codoped make strontium titanate at room temperature have certain ferroelectricity and magnetic.

In the present invention, adopt Pr ⁴⁺/ Pr ³⁺substitute Sr ²⁺, induce the ferroelectricity of strontium titanate, on the one hand because lattice distortion causes, this is obviously and Sr ²⁺(radius=1.44 dust) ion is by the less Pr of radius ³⁺(radius=1.126 dust) and Pr ⁴⁺(radius=0.96 dust) ion replaces relevant.The praseodymium ion that radius is less occupies Sr ²⁺thereby position forms an eccentric position and causes lattice distortion, and Sr-O key bond distance's compression will further cause Ti ion deflection oxygen octahedra center.On the other hand, Pr ⁴⁺/ Pr ³⁺ion occupies eccentric position, can produce dipole, and polar nano microcell will occur around it.Lattice distortion and polar nano microcell are that the ferroelectric reason of room temperature appears in strontium titanate.And Pr content very little, lattice distortion is not obvious; Pr content is too large, the large radius Pr of part ⁴⁺(radius=0.96 dust) ion can occupy Ti ⁴⁺(radius=0.68 dust) ion position, the structure cell that caused thus increases can compensate Pr ³⁺/ Pr ⁴⁺ion occupies Sr ²⁺reducing of the lattice parameter that position causes, thus polarization suppressed.Be Sr in molecular formula _1-xpr _xti _1-yfe _yo ₃material in, the Pr content that the present invention provides is best in 0.025 ~ 0.075 scope.Adopt Fe ³⁺substitute Ti ⁴⁺, the magnetic of strontium titanate derives from the Fe of different occupy-places ³⁺between the indirect superexchange coupling that produces take oxygen as medium.Fe content hour, there will not be magnetic, because Fe interionic in strontium titanate crystals separates; Fe content is too many, Fe ³⁺may more enter in oxygen octahedra room antiferromagnetism Fe ³⁺– O ^2-– Fe ³⁺between superexchange interaction strengthen can suppress magnetic, meanwhile, Fe content too much can cause sample leakage current increase, affect the measurement of ferroelectric hysteresis loop.The Fe content that the present invention provides is better in 0.05 ~ 0.3 scope.Regulate and control the variation of strontium titanate material internal structure and defect by praseodymium element and two kinds of elements of ferro element simultaneously, make it at room temperature can present certain ferroelectricity and magnetic.

Claims (2)

1. a strontium titanate multiferroic film for praseodymium, iron codoped, is characterized in that: be Sr by molecular formula _1-xpr _xti _1-yfe _yo ₃material composition, wherein, the span of x is 0.025≤x≤0.075, the span of y is 0.05≤y≤0.3.

2. the preparation technology of the strontium titanate multiferroic film of a kind of praseodymium according to claim 1, iron codoped, is characterized in that, comprises the following steps:

Step 1, by Sr:Pr:Ti:Fe=(1-x): x:(1-y): the mol ratio of y takes respectively strontium acetate, Praseodymium trioxide, butyl (tetra) titanate and iron nitrate, for subsequent use;

The strontium acetate that step 2, extracting container take step 1 is all dissolved in acetic acid to forming transparent colourless solution, wherein, add the volume of acetic acid and the ratio of strontium acetate gross weight is 4mL:1g, then in solution, add ethylene glycol monomethyl ether, make the volumetric molar concentration of strontium acetate in solution reach 0.6 ~ 0.7mol/L, stir 20 ~ 40min, and then the butyl (tetra) titanate that adds step 1 to take, stir 20 ~ 40min, form solution A, for subsequent use;

The iron nitrate that step 3, another extracting container take step 1 is all dissolved in ethylene glycol monomethyl ether to forming transparent colourless solution, wherein, add the volume of ethylene glycol monomethyl ether and the ratio of iron nitrate gross weight is 1.2mL:1g, after stirring 20 ~ 40min, its mixing solutions is joined in solution A, form solution B, for subsequent use;

It is in 65 ~ 68% concentrated nitric acid that the Praseodymium trioxide that step 4, another extracting container take step 1 is all dissolved in mass percent concentration, wherein, the volume ratio of concentrated nitric acid and acetic acid is 1:3.5, stir after 0.5 ~ 1h, its mixing solutions is joined in solution B, get again appropriate ethylene glycol monomethyl ether difference cleaning step three and the container of step 4, and scavenging solution is poured in solution B, in solution B, add again ethylene glycol monomethyl ether, make the volumetric molar concentration of strontium acetate in solution B reach 0.2mol/L, then stir 6 ~ 8h, filter to obtain solution C, for subsequent use;

Step 5, solution C prepared by step 4 drop on the clean platinum plating silicon substrate being placed in photoresist spinner, and the whirl coating speed that photoresist spinner is set is 3000 ~ 4000 rpm, and the whirl coating time is 25 ~ 35s, makes Sr _1-xpr _xti _1-yfe _yo ₃wet film, by the Sr making _1-xpr _xti _1-yfe _yo ₃wet film is dried after 5min at 200 ℃, carries out thermolysis 5min at 350 ℃, makes Sr _1-xpr _xti _1-yfe _yo ₃dry film, the Sr making _1-xpr _xti _1-yfe _yo ₃on dry film, continue to drip solution C, and repeat successively above-mentioned whirl coating, oven dry and thermal decomposition process, until Sr _1-xpr _xti _1-yfe _yo ₃build reaches 300nm, then in the tube furnace of 700 ~ 750 ℃, the 50 ~ 60min that anneals under nitrogen atmosphere, obtain Sr _1-xpr _xti _1-yfe _yo ₃film.

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