427results about How to "Improve ferroelectric properties" patented technology

The invention discloses a preparing method of niobic acid sodium potassium lithium group leadless piezoelectric ceramic in green energy source material domain, which comprises the following steps: expressing component of niobic acid sodium potassium lithium group as non-stoichiometric ratio general formula (NaaKbLic)(NbxTaySbz)O3 or -nM; expressing a, b, c as A bit element; expressing x, y, z as mole fraction of B bit element; setting the selective rage as (0<=a<=1. 5, 0<=b<=1. 5, 0 C04B 35/495 C04B 35/64 H01B 3/12 H01L 41/187 1 6 1 2007/5/28 101062864 2007/10/31 100465131 2009/3/4 2009/3/4 2009/3/4 University of Science and Technology Beijing Beijing 100083 Zhang Boping Zhao Pei Li Songjie Ding Xiaonian Zhang Hailong liuru e 11207 The Patent Agency of Beijing University of Science and Technology No.30 Xueyuan Road, Beijing 100083

In a method of manufacturing a ferroelectric capacitor, a lower electrode layer is formed on a substrate. The lower electrode layer includes at least one lower electrode film. A ferroelectric layer is formed on the lower electrode layer, and then an upper electrode layer is formed on the ferroelectric layer. A hard mask structure is formed on the upper electrode layer. The hard mask structure includes a first hard mask and a second hard mask. An upper electrode, a ferroelectric layer pattern and a lower electrode are formed by partially etching the upper electrode layer, the ferroelectric layer and the lower electrode layer using the hard mask structure. The hard mask structure may prevent damage to the ferroelectric layer and may enlarge an effective area of the ferroelectric capacitor so that the ferroelectric capacitor may have enhanced electrical and ferroelectric characteristics.

The invention provides layered perovskite structural ceramic and a preparation method thereof. The preparation method includes mixing well titanate compounds, bismuth compounds, strontium compounds, iron compounds, cobalt compounds and complexing agent in solvent, heating, drying and combusting to obtain powder, and presintering to obtain powder; performing the powder, and performing hot-pressing sintering to obtain the structural ceramic in in a formula (I). Compared with ceramics prepared in the prior art by solid phase sintering process, the structural ceramic in the formula (I) is prepared by solution process and hot pressing sintering. The preparation method has the advantages that less volatile low-valence strontium ions are introduced, increased leakage current due to volatilization of the strontium ions is improved, and ferroelectric properties are improved; the raw materials are evenly spread by the solution process, the power is even in component and has high reactivity, and Fe-Co ions are coupled fully; and the materials processed by hot pressing sintering are high in density and orientation, and the layered perovskite structural material can be obtained, namely Bi(n+1-x)SrxF3(n-3)/2Co(n-3)/2Ti3O3(n+1) (I).

The invention relates to a composite multiferroic ceramic (1-x)(Ba, Bi, Na)TiO3-xCoFe2O4, wherein x is more than or equal to 0.1 but less than or equal to 0.5. A production method of the composite multiferroic ceramic is also disclosed. The method comprises the following steps: 1) weighing Bi2O3, Na2CO3, BaTiO3, Co2O3 and Fe2O3 at the given ratio mentioned above, grinding and mixing thoroughly; 2) mixing the fine powder obtained in the step 1) with a binder and mixing thoroughly; 3) compression-molding the powder obtained in the step 2) under 10-20 MPa to obtain sheet with a thickness of 2.0 plus or minus 10% mm; and 4) in a sealed container, placing the sheet obtained in the step 3) over the fine powder obtained in the step 1), covering the sheet with the fine powder, placing the sealed container loading the sheet and powder in a heating furnace, and sintering, to obtain the composite multiferroic ceramic (1-x)(Ba, Bi, Na)TiO3-xCoFe2O4, wherein the sintering temperature is 1000-1250 DEG C and the sintering time lasts 2-3 hours. The product is free of lead and environment-friendly. The production equipment and process are simplified.

The invention discloses a preparation method of a flexible epitaxial ferroelectric film. The preparation method is characterized by 1) preparing a perovskite structure oxide strontium ruthenate bottom electrode by a laser pulse deposition method; 2) preparing a precursor solution of the ferroelectric film by means of a sol-gel method, wherein the concentration of the precursor solution is 0.1-0.5mol/L, the ferroelectric film material is selected from any one of lead zirconate titanate, barium titanate or bismuth ferrite; 3) preparing the flexible epitaxial ferroelectric film, spin-coating the above-mentioned strontium ruthenate bottom electrode with the precursor solution by means of a spin coating method to obtain a uniform wet film; 4) drying, pyrolyzing and annealing the obtained uniform wet film; and (5) repeating steps 3) and 4) for 3-8 times to obtain the target flexible epitaxial ferroelectric film, and the thickness of the film is in the range of 100nm-300nm. The flexible epitaxial ferroelectric film is simple in technology and excellent in ferroelectric performance.

The invention belongs to the field of new inorganic material preparation and technical study, in particular relates to the low-temperature sintering formulation of a high-performance piezoelectric ceramics and the technology thereof. By adding the sintering auxiliary combination of Ba (CU 0.5w 0.5) O3, LiBiO2 and CuO, and adopting the common solid-phase combinatorial synthesis, the method of the invention can prepare ceramics Pb (Ni1/3 Nb2/3) O3-Pb (Zr, Ti) O3. The ceramics can be sintered under the temperature as low as 950 DEG C. The ceramics also boost a sound ferro-voltage electrical property. The key steps of the technical scheme are: synthesizing Pb (Ni1/3 Nb2/3) O3-Pb (Zr, Ti) O3 ceramic powders using Pb3O4, NiO, Nb2O5, TiO2, ZrO2 as ingredients, sintering the ceramic powders into ceramics under different temperatures with additives of Ba (CU 0.5w 0.5) O3, LiBiO2 and CuO. By adding low-melting point sintering auxiliary combination, the sintering temperature can be lowered to 950 DEG C, and the property of the ceramics sintered under low temperature is enhanced.

The invention provides a Bi0.92-xHo0.08AExFe0.97Mn0.03O3-Zn1-yNiyFe2O4 ferromagnetic composite film and a preparation method thereof. The ferromagnetic composite film comprises a Bi0.92-xHo0.08AExFe0.97Mn0.03O3 crystalline film and a Zn1-yNiyFe2O4 crystalline film, which are compounded together. The preparation method is as below: first respectively preparing a Zn1-yNiyFe2O4 precursor solution and a Bi0.92-xHo0.08AExFe0.97Mn0.03O3 precursor solution, wherein AE is Sr, Ca, Ba or Pb, x equals to 0.01-0.04, and y equals to 0.1-0.9; preparing a plurality of Zn1-yNiyFe2O4 films on a substrate by spin coating; and then preparing plurality of Bi0.92-xHo0.08AExFe0.97Mn0.03O3 films on the Zn1-yNiyFe2O4 films by spin coating, so as to obtain the ferromagnetic composite film. The method regulates the crystal structure of BiFeO3 by doping, and uses ferromagnetic Zn1-yNiyFe2O4 as the magnetic layer, so as to substantially increase the ferroelectric and ferromagnetic properties of the film, and effectively reduce the leakage current density of the film.

The invention discloses a ferroelectric thin-film transistor, which comprises a substrate; a bottom gate electrode formed on the substrate; a ferroelectric film layer formed on the bottom gate electrode; a channel layer formed on the ferroelectric film layer; a source electrode formed on the channel layer; and a drain electrode formed on the channel layer and separated from the source electrode. The invention also discloses a preparation method of the ferroelectric thin-film transistor. By introducing a hafnium-oxide-based material and SnO to the transistor to serve as a gate medium material and a channel material of the transistor respectively, the transistor is allowed to be compatible with existing silicon process in the preparation process, and can realize low power consumption; and the ferroelectric thin-film transistor can be widely applied to high-performance and low-power-consumption large-scale storage integrated circuits.

The invention provides a method for preparing an Nd/Co-codoped BiFeO3 film on an FTO (fluorine-doped tin oxide)/glass substrate surface, which comprises the following steps: after cleaning an FTO substrate, carrying out ultraviolet irradiation, and dissolving bismuth nitrate (8% excessive), ferric nitrate, neodymium nitrate and cobalt nitrate which serve as raw materials in mixed ethylene glycol monomethyl ether and acetic anhydride in a mol ratio of 0.98:(1-x):0.1:x (x=0.01-0.05), thereby obtaining a stable BiFeO3 precursor solution of which the metallic ion concentration is 0.1-0.5mol/L; and after spin coating, drying to obtain a dry film, preannealing, naturally cooling, repeating the process above to obtain the film with expected thickness, and finally, annealing to obtain the crystalline BiFeO3 film. In the invention, the facility requests are simple, the experiment conditions can be easily achieved, the prepared film has good uniformity, the doping amount is easy to control, andthe dielectric properties of the film can be greatly enhanced by doping.

The present invention relates to a method for preparing single-phase BiFeO3 ceramic by utilizing quenching process. It is characterized by quickly cooling sintered BiFeO3 ceramic. Said method includes the following steps: weighing Bi2O3 powder and Fe2O3 powder according to the mole ratio of 1:1, ball-grinding for 4-12 hr according to 100-500 rpm, uniformly mixing two powdes, drying the above-mentioned mixed powder, pressing the mixed powder into thin sheet, then placing proper quantity of the above-mentioned mixed powder into Al2O3 crucible, placing the thin sheet into the crucible, and using correspondent powder to cover the thin shet to make the thin sheet and powder be in sealed state, then placing the above-mentioned crucible into heating furnace, heating to sintering temperature, heating speed is 2-8 deg.C/min, sintering temperature is 830-920 deg.C and sintering time is 30-60 min., after sintering process is completed, promptly quenching so as to obtain the invented product.

The present invention provides free-standing heterostructures including a layer of BiFeO₃ and a layer comprising a perovskite over which the BiFeO₃ is epitaxially grown. The layer comprising the perovskite has been released from a substrate upon which it was originally grown. Also provided are methods for forming the free-standing heterostructures, which may include transferring the free-standing heterostructures to other host substrates.

The invention discloses a multiferroic Bi0.96-xSr0.04RExFe0.94Mn0.04Cr0.02O3-NiFe2O4 composite film and a preparation method thereof. The composite film comprises a Bi0.96-xSr0.04RExFe0.94Mn0.04Cr0.02O3 crystalline state film and a NiFe2O4 crystalline state film which are compounded together. The preparation method comprises the following steps: respectively preparing a Bi0.96-xSr0.04RExFe0.94Mn0.04Cr0.02O3 precursor solution and a NiFe2O4 precursor solution; and spinning on a substrate to prepare a multilayer NiFe2O4 film, and spinning on the NiFe2O4 film to prepare a multilayer Bi0.96-xSr0.04RExFe0.94Mn0.04Cr0.02O3 film, thereby obtaining the target product. The equipment requirement is simple, the prepared film is high in uniformity, the doping amount is easy to control, and the ferroelectric properties and ferromagnetic properties of the film are greatly improved. Meanwhile, the leakage current density of the film is effectively reduced.

The invention belongs to the technical field of electronic ceramics, and specifically relates to a bismuth ferrite-strontium bismuth titanatemultiferroic composite film and a preparation method thereof. The bismuth ferrite-strontium bismuth titanatemultiferroic composite film comprises the following raw materials: ferric nitrate, bismuth nitrate, tetrabutyltitanate and strontium acetate. The bismuth ferrite-strontium bismuth titanatemultiferroic composite film has stable structure, and is substantially reduced in leakage current density and strengthened in ferroelectric performance.

The invention discloses a hafnium oxide based ferroelectric grid structure. The structure comprises a substrate, and a buffer layer, a bottom electrode layer, a ferroelectric layer and a top electrode layer are laminated on the surface of the substrate successively, and the material of the ferroelectric layer comprises hafnium oxide. The invention also discloses a preparation technology of the hafnium oxide based ferroelectric grid structure. The hafnium oxide based ferroelectric grid structure has high electrical performances, the vertical size of the whole storage medium of a ferroelectric memory is reduced by 10 to 20 times, and the structure and technology are compatible with the silicon technology.

The invention discloses a method for preparing a Hf0.5Zr0.5O2 ferroelectric film by ALD for ferroelectric memory applications, characterized by preparing the ferroelectric film by using atomic layer deposition, using a hafnium source and a zirconium source as reaction precursors, using ozone or water as an oxygen source, using a cavity temperature of 250 to 280 degrees centigrade, and using a reaction precursor heating temperature of 75 to 80 degrees centigrade. Compared with a ferroelectric film having a perovskite structure obtained by a conventional process, the ferroelectric film preparedby the method is more liable to be compatible with a standard semiconductor manufacturing process, has higher integration, a lower annealing temperature, a higher annealing rate, shorter annealing time, and a lower ferroelectric layer thickness. The film obtained by a high annealing rate heat treatment process has high remanent polarization, a large dielectric constant, and low leakage current. The preparation method of the invention has high repeatability and can obtain uniform ferroelectric film, and contributes to realizing the wide application prospect of the ferroelectric film in the fields of information storage and integrated circuits.

The invention relates to a layered structure ferrotitanium lanthanum bismuth cobaltate ceramic with multiferroic and a preparation method thereof, relating to the technical field of oxide ceramic material preparation. The method comprises the following steps: firstly preparing Bi3.25L0.75Ti3O15 powder, then implanting BiCoO3 and BiFeO3 in Bi3.25L0.75Ti3O15 to form Bi4.25L0.75Fe0.5Co0.5Ti3O15 ceramic. In the obtained BLFCT sample, the octahedral arrangement of Fe-O and Co-O is relatively orderly so that the local coupling between Fe-O-Co and La-O-Co/Fe can be obtained and the ferroelectric property and magnetic property of the sample can be improved. The ceramic of the invention has simple and reasonable technology and good compatibility with the current technology, and the sample preparation temperature is much lower than the preparation temperature of the current technology so as to greatly reduce the energy consumption, thus the ceramic is applicable to industrial production.

The invention discloses a method for preparing a Bi0.85Sm0.15Fe1-xCrxO3 ferroelectric film via a sol-gel process. The method is carried out by the following steps of: washing an FTO (Fluorinedoped Tin Oxide) substrate and subsequently irradiating via ultraviolet light; using bismuth nitrate, ferric nitrate, samarium nitrate and chromic nitrate as raw materials (the bismuth nitrate excesses by 5%), dissolving the above raw materials in mixed ethylene glycol monomethyl ether and acetic anhydride according to a mole ratio of 0.90: (1-x):0.15:x (x is 0.00, 0.01, 0.02 or 0.03), then adding ethanol amine to adjust a viscosity and obtain a stable BiFeO3 (bismuth ferrite) precursor solution with a metal ion concentration of 0.003-0.3mol/L; and homogenizing and subsequently obtaining a dry film, then using a layer-by-layer annealing process to obtain a crystal-state Bi0.85Sm0.15Fe1-xCrxO3 ferroelectric film. The method disclosed by the invention has the advantages of simple device requirement, easy achievement of experiment condition, good uniformity of the prepared films and easy control of the doping amount, so that the ferroelectric performance of the film is greatly enhanced.

The invention provides a method for preparing a Gd and Co codoped high-remanent-polarization BiFeO3 thin film by a sol-gel method. The method comprises the steps that Bi(NO3)3*5H2O, Fe(NO3)3*9H2O, Gd(NO3)3*6H2O and Co(NO3)2*6H2O are dissolved in ethylene glycol monomethyl ether, and then heated and stirred in an 80 DEG C water bath for 1h; acetic anhydride is added and stirred for 1h; a BiFeO3 precursor solution is obtained and stands for 24h; an FTO (Fluorinedoped Tin Oxide)/glass substrate is subjected to spin coating with the BiFeO3 precursor solution for preparing a thin film; the thin film is subjected to rapid annealing at 550 DEG C, and then cooled to a room temperature; and spin coating and rapid annealing processes are repeated till the BiFeO3 thin film with the required thickness is prepared. The adopted sol-gel method does not require expensive equipment, and is suitable for preparing the thin film on a large surface and a surface with an irregular shape; in addition, chemical constituents are precise and controllable; the ferroelectric property of the prepared BiFeO3 thin film is improved under coaction of Gd and Co.

The invention discloses a piezoelectric material for lead-free piezoelectric ceramic with potassium-sodium niobate and a preparing method, which strengthens the ferroelectric performance of potassium-sodium niobate ceramic and further improves the piezoelectric performance. The material of the invention comprises anhydrous potassium carbonate, natrium carbonicum calcinatum, niobium pentaoxide and dibismuth trioxide, the stoichiometric proportion of the lead-free piezoelectric ceramic is (K0.5 Na0.5) Nb3 + x weight percent Bi 2O3, wherein the x is more than or equal to 0 and less than or equal to 1, the piezoelectric material for lead-free piezoelectric ceramic with potassium-sodium niobate is obtained through mixture making, drying and burnishing, granulation, molding, sintering and after polarization by a silver electrode; therefore, the densification of the ceramic is improved, polarized drain current of the ceramic is reduced, and the polarization process is carried out more easily; moreover, the piezoelectric material adopts the material from a conventional process and industry, has the characteristics of good process stability and no pollution.

A novel sodium niobate lithium tantalate series lead-free piezoelectric ceramic composite comprises perovskite anti-ferroelectrics NaNbO3 and lithium niobate ferroelectrics LiTao3 and is represented as formula (1-x)NaNbO3-xLiTaO3, wherein 0.025<=x<=0.25. The lead-free piezoelectric ceramic composite further comprises one kind or a plurality of kinds of oxides, formula of the lead-free piezoelectric ceramic composite is (1-x)NaNbO3-xLiTaO3 ((110-a)mol%)+M alpha O beta (amol%), the M alpha O beta is one kind or a plurality of kinds of oxides, molar ratio of a content to main component (1-x)NaNbO3-xLiTaO3 is 0-3%, M is an element which is from +1 to +6 and capable of forming a solid-state oxide with oxygen, and the alpha and the beta respectively show atomic numbers of corresponding element M and the oxygen in the oxide. The optimal value d33 of the piezoelectric ceramic composite can reach above 70pC/N, kp can reach above 20%, and Qm can reach above 1200. The composite is good in compactness, high in Curie temperature, good in heat stability and stable in process, is obtained by adopting the tradition piezoelectric ceramic manufacturing technology, and has practicability.