CN103833353B - Preparation process for praseodymium- iron- co-doped strontium titanate multiferroic film - Google Patents

Abstract

The invention relates to a preparation process of a praseodymium- iron- co-doped strontium titanate multiferroic film. 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

The preparation technology of the strontium titanates multiferroic film of a kind of praseodymium, iron codope

Technical field

The present invention relates to the preparation of multiferroic film in materials science field, specifically the preparation technology of the strontium titanates multiferroic film of a kind of praseodymium, iron codope.

Background technology

Single-phase multi-ferroic material refers to the single-phase compounds simultaneously showing ferroelectricity and magnetic.Because various ferrous is in together in an individual system, unavoidably will interact between them, thus the mutual regulation and control that can realize 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 the low temperature of pole, mainly some Mn oxides, such as: BiMnO ₃, YMnO ₃and HoMnO ₃deng, these material magnetic transition temperature all at below 100K, and due to synthesize difficulty, preparation cost high, need the condition restrictions such as HTHP, also have certain distance from practical application.In all single phase multi-iron materials, BiFeO ₃be one of material being hopeful most to be applied, its major advantage is to have very high ferroelectrie Curie temperature and antiferromagnetic transition temperature, shows the material of ferroelectricity and magnetic while of being almost unique so far more than room temperature.But it also exists synthesis difficult problem, and Fe is caused to appraise at the current rate with non-stoichiometric and there is the reasons such as various dephasigns, BiFeO because Bi in sample volatilizees ₃have very large leakage current, this makes BiFeO ₃excellent performance particularly electric hysteresis loop is difficult to present.Therefore, obtaining a kind of preparation technology 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 solve existing single-phase multi-ferroic material phase transition temperature low, synthesis difficulty and high in cost of production problem, the preparation technology of the strontium titanates multiferroic film of a kind of praseodymium, iron codope is provided, preparation technology is simple, and the strontium titanates multiferroic film of preparation at room temperature can show ferroelectricity and magnetic.

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

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

Step one, by Sr:Pr:Ti:Fe=(1-x): x:(1-y): the mol ratio of y takes strontium acetate, praseodymium oxide, butyl titanate and ferric nitrate respectively, for subsequent use;

The strontium acetate that step one takes by step 2, extracting container is all dissolved in acetic acid to forming transparent colourless solution, wherein, the added volume of acetic acid and the ratio of strontium acetate total weight are 4mL:1g, then add EGME in the solution, make the molar concentration of strontium acetate in solution reach 0.6 ~ 0.7mol/L, stir 20 ~ 40min, and then add the butyl titanate that step one takes, stir 20 ~ 40min, form solution A, for subsequent use;

The ferric nitrate that step one takes by step 3, another extracting container is all dissolved in EGME to forming transparent colourless solution, wherein, the added volume of EGME and the ratio of ferric nitrate total weight are 1.2mL:1g, after stirring 20 ~ 40min, its mixed solution is joined in solution A, form solution B, for subsequent use;

It is in the red fuming nitric acid (RFNA) of 65 ~ 68% that the praseodymium oxide that step one takes by step 4, another extracting container is all dissolved in mass percent concentration, wherein, the volume ratio of red fuming nitric acid (RFNA) and acetic acid is 1:3.5, after stirring 0.5 ~ 1h, its mixed solution is joined in solution B, get appropriate EGME difference cleaning step three and the container of step 4 again, and cleaning fluid is poured in solution B, EGME is added again in solution B, the molar concentration of strontium acetate in solution B is made to reach 0.2mol/L, then stir 6 ~ 8h, filter to obtain solution C, for subsequent use;

Step 5, solution C step 4 prepared drop on the platinum plating silicon substrate of the cleaning be placed in photoresist spinner, and the whirl coating speed arranging photoresist spinner is 3000 ~ 4000 rpm, and the whirl coating time is 25 ~ 35s, obtained Sr _1-xpr _xti _1-yfe _yo ₃wet film, by obtained Sr _1-xpr _xti _1-yfe _yo ₃after wet film dries 5min at 200 DEG C, at 350 DEG C, carry out thermal decomposition 5min, obtained Sr _1-xpr _xti _1-yfe _yo ₃dry film, at obtained Sr _1-xpr _xti _1-yfe _yo ₃dry film continues drip solution C, and repeat above-mentioned whirl coating, oven dry and thermal decomposition process successively, until Sr _1-xpr _xti _1-yfe _yo ₃build reaches 300nm, then in the tube furnace of 700 ~ 750 DEG C, under nitrogen atmosphere anneal 50 ~ 60min, 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 oxide purity is 99.5%, and ferric nitrate purity is 99%, and the purity of EGME is 99%.

In the present invention, strontium element and praseodymium elemental mole ratios 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 along with doped chemical Pr different with the concentration of Fe and different, when doping content is too low, when namely the value of x and y is less than normal, strontium titanates is difficult to occur ferroelectricity and magnetic; When doping content is too high, when namely the value of x is bigger than normal, polarization can reduce with the increase of Pr content, and these are different from Pr constituent content, Pr ³⁺/ Pr ⁴⁺the change of relative scale relevant.Partial radius is the Pr of 0.96 dust ⁴⁺ion can occupy the Pr that radius is 0.68 dust ⁴⁺ion position, structure cell caused thus increases, and can compensate Pr ³⁺/ Pr ⁴⁺ion occupies Sr ²⁺the reduction of the lattice parameter that position causes, thus inhibit polarization; When the value of y is bigger than normal, iron ion increases, Fe ²⁺and Fe ³⁺between electron transition leakage current to be caused in sample to increase, also make thin-film ferroelectric be difficult to occur.

Beneficial effect: (1), the present invention adopt metal-organic decomposition method, induced ferroelectricity and the magnetic of strontium titanates by praseodymium, iron codope simultaneously, achieve 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), the present invention induce the ferroelectricity of strontium titanates and magnetic appears near room temperature, only can could there is ferroelectricity and Magnetic Phase ratio at low temperatures with traditional single-phase multi-ferroic material simultaneously, have a good application prospect;

(3) strontium acetate, in the present invention, praseodymium oxide, metatitanic acid fourth fat and ferric nitrate are respectively as the predecessor of strontium element, praseodymium element, titanium elements and ferro element, acetic acid, EGME and red fuming nitric acid (RFNA) are as solvent, The present invention gives the adding proportion of each solvent and the step of configuration solution C, this makes the acidity of solution C, stability and viscosity etc. reach optimum state, thus improve uniformity and the density of obtained film phase, reach the object that stabilizing solution improves film sintered performance.

Accompanying drawing explanation

Fig. 1 is the praseodymium of embodiment 1,2 and 3 preparation, the strontium titanates XRD of iron codope schemes;

Fig. 2 be embodiment 1,2 and 3 prepare praseodymium, iron codope strontium titanates room temperature under the electric hysteresis loop figure that measures;

Fig. 3 be embodiment 1,2 and 3 prepare praseodymium, iron codope strontium titanates room temperature under the magnetic hysteresis loop figure that measures.

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

Embodiment

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

Embodiment 1

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

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

Step 2, strontium acetate step one taken all are dissolved in acetic acid to forming transparent colourless solution, wherein, the added volume of acetic acid and the ratio of strontium acetate total weight are 4mL:1g, then add EGME, make the molar concentration of strontium acetate in solution reach 0.6mol/L, stir 30min, and then add the butyl titanate that step one takes, stir 30min, form solution A, for subsequent use;

Step 3, ferric nitrate step one taken all are dissolved in EGME to forming transparent colourless solution, wherein, the volume of added EGME and the ratio of ferric nitrate total weight are 1.2mL:1g, join in solution A after stirring 30min by its mixed solution, form solution B, for subsequent use;

Step 4, it is in the red fuming nitric acid (RFNA) of 65 ~ 68% that praseodymium oxide step one taken all is dissolved in mass percent concentration, wherein, the molar concentration of red fuming nitric acid (RFNA) is 16mol/L, the volume ratio of red fuming nitric acid (RFNA) and acetic acid is 1:3.5, after stirring 1h, its mixed solution is joined in solution B, and use the EGME cleaning step three of 2mL and step 4 beaker inwall used respectively, spend the iron-residues on removing beaker inwall and praseodymium residue respectively, and cleaning fluid is poured in solution B, and then add appropriate EGME, the molar concentration of strontium acetate in solution is made to reach 0.2mol/L, then 8h is stirred, filter to obtain precursor aqueous solution C, for subsequent use,

Step 5, precursor aqueous solution C step 4 prepared drop in platinum plating silicon substrate (111) Pt/Ti/SiO of the cleaning be placed in photoresist spinner ₂on/Si, the whirl coating speed arranging photoresist spinner is 3500 rpm, and the whirl coating time is 30s, obtained Sr _0.975pr _0.025ti _0.9fe _0.1o ₃wet film, by obtained Sr _0.975pr _0.025ti _0.9fe _0.1o ₃after wet film dries 5min at 200 DEG C, at 350 DEG C, carry out thermal decomposition 5min, obtained Sr _0.975pr _0.025ti _0.9fe _0.1o ₃dry film, at obtained Sr _0.975pr _0.025ti _0.9fe _0.1o ₃dry film continues drip precursor aqueous solution C, and repeat above-mentioned whirl coating, oven dry and thermal decomposition process successively, until Sr _0.975pr _0.025ti _0.9fe _0.1o ₃build reaches 300nm, then in the tube furnace of 750 DEG C, anneal under nitrogen atmosphere 60min, obtains Sr _0.975pr _0.025ti _0.9fe _0.1o ₃film.

Embodiment 2

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

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

Step 2, strontium acetate step one taken all are dissolved in acetic acid to forming transparent colourless solution, wherein, the added volume of acetic acid and the ratio of strontium acetate total weight are 4mL:1g, then add EGME, make the molar concentration of strontium acetate in solution reach 0.6mol/L, stir 30min, and then add the butyl titanate that step one takes, stir 30min, form solution A, for subsequent use;

Step 3, ferric nitrate step one taken all are dissolved in EGME to forming transparent colourless solution, wherein, the volume of added EGME and the ratio of ferric nitrate total weight are 1.2mL:1g, join in solution A after stirring 30min by its mixed solution, form solution B, for subsequent use;

Step 4, it is in the red fuming nitric acid (RFNA) of 65 ~ 68% that praseodymium oxide step one taken all is dissolved in mass percent concentration, wherein, the molar concentration of red fuming nitric acid (RFNA) is 16mol/L, the volume ratio of red fuming nitric acid (RFNA) and acetic acid is 1:3.5, after stirring 50min, its mixed solution is joined in solution B, and use the EGME cleaning step three of 2mL and step 4 beaker inwall used respectively, spend the iron-residues on removing beaker inwall and praseodymium residue respectively, and cleaning fluid is poured in solution B, and then add appropriate EGME, the molar concentration of strontium acetate in solution is made to reach 0.2mol/L, then 7h is stirred, filter to obtain precursor aqueous solution C, for subsequent use,

Step 5, precursor aqueous solution C step 4 prepared drop in platinum plating silicon substrate (111) Pt/Ti/SiO of the cleaning be placed in photoresist spinner ₂on/Si, the whirl coating speed arranging photoresist spinner is 3800 rpm, and the whirl coating time is 25s, obtained Sr _0.975pr _0.025ti _0.8fe _0.2o ₃wet film, by obtained Sr _0.975pr _0.025ti _0.8fe _0.2o ₃after wet film dries 5min at 200 DEG C, at 350 DEG C, carry out thermal decomposition 5min, obtained Sr _0.975pr _0.025ti _0.8fe _0.2o ₃dry film, at obtained Sr _0.975pr _0.025ti _0.8fe _0.2o ₃dry film continues drip precursor aqueous solution C, and repeat above-mentioned whirl coating, oven dry and thermal decomposition process successively, until Sr _0.975pr _0.025ti _0.8fe _0.2o ₃build reaches 300nm, then in the tube furnace of 750 DEG C, anneal under nitrogen atmosphere 60min, obtains Sr _0.975pr _0.025ti _0.8fe _0.2o ₃film.

Embodiment 3

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

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

Step 2, strontium acetate step one taken all are dissolved in acetic acid to forming transparent colourless solution, wherein, the added volume of acetic acid and the ratio of strontium acetate total weight are 4mL:1g, then EGME is added, stir 35min, and then add the butyl titanate that step one takes, stir 35min, form solution A, for subsequent use;

Step 3, ferric nitrate step one taken all are dissolved in EGME to forming transparent colourless solution, wherein, the volume of added EGME and the ratio of ferric nitrate total weight are 1.2mL:1g, join in solution A after stirring 40min by its mixed solution, form solution B, for subsequent use;

Step 4, it is in the red fuming nitric acid (RFNA) of 65 ~ 68% that praseodymium oxide step one taken all is dissolved in mass percent concentration, wherein, the molar concentration of red fuming nitric acid (RFNA) is 16mol/L, the volume ratio of red fuming nitric acid (RFNA) and acetic acid is 1:3.5, after stirring 50min, its mixed solution is joined in solution B, and use the EGME cleaning step three of 2mL and step 4 beaker inwall used respectively, spend the iron-residues on removing beaker inwall and praseodymium residue respectively, and cleaning fluid is poured in solution B, and then add appropriate EGME, the molar concentration of strontium acetate in solution is made to reach 0.2mol/L, then 7h is stirred, filter to obtain precursor aqueous solution C, for subsequent use,

Step 5, precursor aqueous solution C step 4 prepared drop in platinum plating silicon substrate (111) Pt/Ti/SiO of the cleaning be placed in photoresist spinner ₂on/Si, the whirl coating speed arranging photoresist spinner is 3000 rpm, and the whirl coating time is 35s, obtained Sr _0.975pr _0.025ti _0.7fe _0.3o ₃wet film, by obtained Sr _0.975pr _0.025ti _0.7fe _0.3o ₃after wet film dries 5min at 200 DEG C, at 350 DEG C, carry out thermal decomposition 5min, obtained Sr _0.975pr _0.025ti _0.7fe _0.3o ₃dry film, at obtained Sr _0.975pr _0.025ti _0.7fe _0.3o ₃dry film continues drip precursor aqueous solution C, and repeat above-mentioned whirl coating, oven dry and thermal decomposition process successively, until Sr _0.975pr _0.025ti _0.7fe _0.3o ₃build reaches 300nm, then in the tube furnace of 700 DEG C, anneal under nitrogen atmosphere 60min, obtains Sr _0.975pr _0.025ti _0.7fe _0.3o ₃film.

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

Be illustrated in figure 1 the praseodymium of embodiment 1,2 and 3 preparation, the strontium titanates XRD of iron codope schemes, as shown in Figure 1, after doping, the one-tenth of strontium titanates is mutually good; Fig. 2 and Fig. 3 shows strontium titanate film and presents certain ferroelectricity and magnetic, the strontium titanate film that each embodiment obtains can cash out ferroelectricity and magnetic room temperature 25 DEG C, but along with the increase of Fe content, ferroelectricity and magnetic weaken gradually, and the strontium titanate film that embodiment 1 and embodiment 2 obtain is functional; As Ti/Fe=0.7/0.3, electric hysteresis loop shape gross distortion, this be iron ion appraise at the current rate cause this sample leakage current increase caused by.Can be shown by Fig. 1 to Fig. 3, praseodymium, iron codope make strontium titanates 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 titanates, on the one hand because distortion of lattice causes, this 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⁺position forms an eccentric position thus causes distortion of lattice, and the compression of Sr-O key bond distance will cause Ti ion deflection oxygen octahedra center further.On the other hand, Pr ⁴⁺/ Pr ³⁺ion occupies eccentric position, can produce dipole, and polar nano microcell will occur around it.Distortion of lattice and polar nano microcell are that the ferroelectric reason of room temperature appears in strontium titanates.And Pr content very little, distortion of lattice 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, structure cell caused thus increases can compensate Pr ³⁺/ Pr ⁴⁺ion occupies Sr ²⁺the reduction of the lattice parameter that position causes, thus inhibit polarization.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 titanates derives from the Fe of different occupy-place ³⁺between be the indirect superexchange coupling that medium produces with oxygen.When Fe content is less, there will not be magnetic, because Fe interionic in strontium titanate crystals is separated; Fe content is too many, Fe ³⁺may more enter in oxygen octahedra room, antiferromagnetism Fe ³⁺– O ²– Fe ³⁺between superexchange interaction enhancing can suppress magnetic, meanwhile, Fe content too much can cause the leakage current of sample to increase, and affects the measurement of electric hysteresis loop.The Fe content that the present invention provides is better in 0.05 ~ 0.3 scope.Regulated and controled the change of strontium titanate material internal structure and defect by praseodymium element and ferro element two kinds of elements simultaneously, make it at room temperature can present certain ferroelectricity and magnetic.

Claims (1)

1. a preparation technology for the strontium titanates multiferroic film of praseodymium, iron codope is Sr by molecular formula _1-xpr _xti _1-yfe _yo ₃material composition, wherein, the span of x is 0.025≤x≤0.075, and the span of y is 0.05≤y≤0.3, it is characterized in that, comprises the following steps:

Step one, by Sr:Pr:Ti:Fe=(1-x): x:(1-y): the mol ratio of y takes strontium acetate, praseodymium oxide, butyl titanate and ferric nitrate respectively, for subsequent use;

The strontium acetate that step one takes by step 2, extracting container is all dissolved in acetic acid to forming transparent colourless solution, wherein, the added volume of acetic acid and the ratio of strontium acetate total weight are 4mL:1g, then add EGME in the solution, make the molar concentration of strontium acetate in solution reach 0.6 ~ 0.7mol/L, stir 20 ~ 40min, and then add the butyl titanate that step one takes, stir 20 ~ 40min, form solution A, for subsequent use;

The ferric nitrate that step one takes by step 3, another extracting container is all dissolved in EGME to forming transparent colourless solution, wherein, the added volume of EGME and the ratio of ferric nitrate total weight are 1.2mL:1g, after stirring 20 ~ 40min, its mixed solution is joined in solution A, form solution B, for subsequent use;

It is in the red fuming nitric acid (RFNA) of 65 ~ 68% that the praseodymium oxide that step one takes by step 4, another extracting container is all dissolved in mass percent concentration, wherein, the volume ratio of red fuming nitric acid (RFNA) and acetic acid is 1:3.5, after stirring 0.5 ~ 1h, its mixed solution is joined in solution B, get appropriate EGME difference cleaning step three and the container of step 4 again, and cleaning fluid is poured in solution B, EGME is added again in solution B, the molar concentration of strontium acetate in solution B is made to reach 0.2mol/L, then stir 6 ~ 8h, filter to obtain solution C, for subsequent use;

Step 5, solution C step 4 prepared drop on the platinum plating silicon substrate of the cleaning be placed in photoresist spinner, and the whirl coating speed arranging photoresist spinner is 3000 ~ 4000 rpm, and the whirl coating time is 25 ~ 35s, obtained Sr _1-xpr _xti _1-yfe _yo ₃wet film, by obtained Sr _1-xpr _xti _1-yfe _yo ₃after wet film dries 5min at 200 DEG C, at 350 DEG C, carry out thermal decomposition 5min, obtained Sr _1-xpr _xti _1-yfe _yo ₃dry film, at obtained Sr _1-xpr _xti _1-yfe _yo ₃dry film continues drip solution C, and repeat above-mentioned whirl coating, oven dry and thermal decomposition process successively, until Sr _1-xpr _xti _1-yfe _yo ₃build reaches 300nm, then in the tube furnace of 700 ~ 750 DEG C, under nitrogen atmosphere anneal 50 ~ 60min, obtain Sr _1-xpr _xti _1-yfe _yo ₃film.