173 results about "Residual polarization" patented technology

A memory wherein any “disturb effect” can be suppressed in which data in unselected memory cells are lost. This memory has a memory cell array(1) including bit lines, word lines, which are disposed to intersect the bit lines, and memory cells(12) each connected between bit and word lines. In this memory, an access operation, which includes at least one of read, rewrite and write operations, is made to a selected memory cell(12). During this access operation, it is performed to apply to the memory cell(12) a first voltage pulse, which provides an electrical field in a first direction so as to invert a stored data, and a second voltage pulse, which provides as electrical field in the opposite direction to the first one so as not to invert the stored data. In addition, a recovery operation for recovering a residual polarization amount is made to the memory cell(12).

The invention provides a method for preparing a piezoelectric-ferroelectric thin film, relating to the technical field of preparation of lead zirconate titanate ceramics and being realized by the steps of preparing a precursor solution, utilizing a PLD method to prepare a substrate and adopting a Sol-Gel method to prepare the piezoelectric-ferroelectric thin film on a PZT crystal seed layer. The invention utilizes a method combing PLD and Sol-Gel to prepare a PZT thick film, thus having strong applicability to different substrates; and the prepared PZT thick film has the obvious advantages of high preferred orientation, even crystal size and compact structure, and can be used for preparing a lead zirconate titanate thin film with the thickness of 3-6 microns, the residual polarization value Pr of 25-45 mu C/cm<2> and the coercive field Ec of 40-65 kV/cm. At the same time, the method in the invention has relative low cost, strong controllability of programs and high industrialized application value.

The invention relates to a BiFeO3-base sandwich structure film used for a ferroelectric memory and a process for preparation, belonging to the technical field of microelectronic new materials, wherein the upper surface component and the lower surface component of the BiFeO3-base sandwich structure film both are BiFe1-xHxO3, H is doped high valence ion with quadravalence or over quadravalence, the component of the intermediate layer is BiFe1-xLxO3, L is doped high valence ion with trivalence or below trivalence. The process for preparation comprises adopting the chemical solution method combined with the annealing technology in layer by layer, and preparing through depositing precursor solution in the surface layers of different materials in the spin-coating method. The invention greatly reduces the drain current of the film through adopting a special sandwich structure, effectively reduces coercive field, significantly increases the charge retention, obtains the ferroelectric film with low drain current, large residual polarization, low coercive field and excellent charge retention under the annealing temperature of 500 DEG C-600 DEG C, and has great practicable prospects in further ferroelectric memories.

This invention discloses a method for preparing highly (111)-oriented PZT thin film. The method can solve the problems of complex process and low repeatability faced by sol-gel method. The method comprises: preparing PZT sol, depositing PZT thin film, pre-crystallizing PZT thin film, and crystallizing PZT thin film. The method is simple. The obtained PZT thin film has compact and smooth surface, uniform thickness, uniform grain sizes, high residual polarization value (43-60 muC/cm2), low coercive field (60-75 kV/cm), and high saturated polarization value.

The invention discloses a composite solid solution film based on sodium bismuth titanate and bismuth ferric and a preparation method thereof. The film is represented by the general formula: (1-x)Na0.5(Bi0.95Ce0.05)0.5TiO(3-x)BiFe0.97Mn0.03O3, the sodium bismuth titanate is Na0.5(Bi0.95Ce0.05)0.5TiO3, and the bismuth ferric is BiFe0.97Mn0.03O3, wherein x is the molar content of BiFe0.97Mn0.03O3, which is greater than 0 and less than 1. According to the invention, the composite solid solution film is prepared by the spinning method-layer by layer annealing process, and does not have an impurityphase except that a pyrochlore impurity phase exists when x is less than or equal to 0.05; and moreover, the film has the advantages of low crystallizing temperature, low electric leakage, great residual polarization, stable dielectric property and the like, and can be well applied to novel high-density integrated piezoelectric ferroelectric devices in the future.

The invention discloses a battery SOC (state of charge) estimation method based on polarization voltage recovery characteristics. The method comprises two parts: analysis of battery polarization voltage characteristics and SOC estimation based on polarization voltage recovery characteristics, wherein in the first part, based on the battery standing voltage curves under different battery SOC, the battery residual polarization voltage in different standing time is extracted, the maximum battery voltage deviation allowable at the SOC error of 3% or below is derived from the OCV-SOC curve, and theminimum standing time for eliminating polarization voltage under different SOC is obtained while guaranteeing the SOC error of 3%; in the second part, according to the battery minimum standing time under different SCO of the same-batch batteries and the law of aging with time, a response surface model is adopted as an approximate model, and an accurate approximation function relationship is obtained in a local scope by using a few data points, so as to obtain the minimum standing time that guarantees the SOC error being within 3% in the whole life cycle of the battery; corresponding battery SOC is estimated according to whether the standing time reaches the minimum standing time.

The invention provides an operating method for realizing multi-bit data storage of a ferroelectric memory, belonging to the technical field of micro-electronics. The method comprises the following steps: in a storage unit of a ferroelectric memory, leading a ferroelectric film to correspondingly generate residual polarization intensity with different magnitudes by additionally increasing different writing pulse voltages and correspondingly defining the residual polarization intensity into different storage states; and reading all the corresponding storage states by a fixed additionally increased right-reading voltage, thereby realizing the multi-bit storage in a single storage unit. The operating method for realizing multi-bit data storage enables a multi-bit storage device to greatly improve the storage density and greatly reduce the production cost.

The invention relates to a lead lutecium niobate-lead zirconate titanate piezoceramic material. The performance is represented through powder diffraction, a scanning electron microscope, dielectric, piezoelectric and ferroelectric measurement, so the morphotropic phase boundary region of a ternary system is determined and the component 43Pb (Lu1/2Nb1/2) O3-10PbZrO3-47PbTiO3 with the best performance in the morphotropic phase boundary region is obtained, wherein the piezoelectric coefficient d33 is equal to 367 pC/N and Tc is equal to 360 DEG C; the electromechanical coupling property kp is equal to 68 percent; the coercive field Ec is equal to 17 kv/cm; and the residual polarization Pr is equal to 34.45 uC/cm2. The requirement of high technology application such as high-powder sensors, high-strain drivers and the like on the performance of the piezoelectric material can be met, and the requirement of high technology application such as high-powder sensors, high-strain drivers and the like on the using temperature of the piezoelectric material can also be met.

Provided is an optical element rotation type Mueller-matrix ellipsometer for solving a problem of measurement accuracy and measurement precision occurring due to residual polarization of a light source, polarization dependence of a photo-detector, measurement values of Fourier coefficients of a high order term in dual optical element rotation type Mueller-matrix ellipsometers according to the related art capable of measuring some or all of components of a Mueller-matrix for any sample.

A field-effect transistor is provided which includes: a first nitride semiconductor layer having a lattice constant a₁ and a bandgap Eg₁; a second nitride semiconductor layer stacked on the first nitride semiconductor layer and having a lattice constant a₂ and a bandgap Eg₂; a source electrode and a drain electrode formed on the second nitride semiconductor layer; a piezo-effect film formed on the second nitride semiconductor layer in a region between the source electrode and the drain electrode; and a gate electrode formed on a region of the piezo-effect film. The relation between the lattice constants a₁ and a₂ is a₁>a₂. The relation between the bandgaps Eg₁ and Eg₂ is Eg₁<Eg₂. The residual polarization density at that surface of the piezo-effect film which faces the second nitride semiconductor layer is equal to or higher than the density of electric charges of a two-dimensional electron gas layer at an interface between the first nitride semiconductor layer and the second nitride semiconductor layer, and negative charges are polarized at that surface of the piezo-effect film which faces the second nitride semiconductor layer.

A semiconductor device has a ferroelectric field-effect transistor having a gate portion whose equivalent circuit is composed of a ferroelectric capacitor C_F and a paraelectric capacitor C_P connected in series, the ferroelectric field-effect transistor having a threshold voltage V_TH corresponding to a residual polarization of the ferroelectric capacitor C_F, and a control portion (not shown) writing a residual polarization state corresponding to a potential difference between the gate and the back gate of the ferroelectric field-effect transistor by fixing the gate potential of the ferroelectric field-effect transistor (for example, fixing it to a ground potential) and changing the back gate potential of the ferroelectric field-effect transistor (for example, switching it between +10 V and −10 V).

The invention relates to the metalworking field, particularly to electrochemical sizing machining, and can be used for manufacturing of machine workpieces having an intricate profile and shaping furniture from chromium-containing steels and alloys operating in aggressive environment under excessive friction.

Technical effect: improving machining accuracy by forming a lustrous layer on the machined surface and reduction of concentration of hexavalent toxic chromium ions in a waste electrolyte solution.

Summary of invention: in the initial step, the unipolar electrochemical machining by operating pulses of normal polarity is carried out forming a layer enriched with chromium ions in the electrolyte area adjacent to the workpiece surface, then, upon achievement of the predetermined machining depth, shape and size of the workpiece, the operational current pulses of normal polarity and the machining electrode feeding are turned off and the residual polarization voltage value at the interelectrode gap is measured using the test high-frequency pulses of normal polarity, then low voltage pulses of opposite polarity synchronized with the phase of maximal approximation of the electrodes to each other are turned on and chromium cathode deposition onto the machined workpiece surface is carried out by means of alternating the pulses of opposite polarity with test high-frequency pulses of normal polarity and controlling the chromium deposition by increment of residual polarization value relative to its value after operational pulses of normal polarity.

The invention provides a laminated BiFe(0.97-x)Mn0.03TMxO3/CoFe2O4 multiferroic composite film and a preparation method thereof. The composite film comprises a BiFe(0.97-x)Mn0.03TMxO3/CoFe2O4 crystallized film and a CoFe2O4 crystallized film which are compounded together. The preparation method comprises the following steps of firstly, preparing a BiFe(0.97-x)Mn0.03TMxO3/CoFe2O4 precursor solution and a CoFe2O4 precursor solution respectively; and then carrying out spin coating on a substrate to prepare a multi-layer CoFe2O4 film, and then carrying out spin coating on the CoFe2O4 film so as to prepare a multi-layer BiFe(0.97-x)Mn0.03TMxO3/CoFe2O4 film, thereby obtaining the target product. According to the invention, the equipment requirement is simple; the prepared film is good in uniformity; chemical components are accurate and controllable; the doped amount is easy to control; the ferroelectric properties and the ferromagnetic property of a film are improved greatly, so that the film has high residual polarization value and a residual magnetization value.

The invention relates to a ferroelectric composite Cu2O visible light water photolysis hydrogen production photocathode and a preparing method thereof. The photocathode is sequentially composed of a BiFeO3 ferroelectric film layer, a gold nano-rod granular layer, a Cu2O film layer and a silicon wafer substrate from top to bottom, and heterojunctions are formed between the Cu2O film layer and the BiFeO3 ferroelectric film layer. According to the ferroelectric composite Cu2O visible light water photolysis hydrogen production photocathode and the preparing method of the photocathode, adverse effects of energy band barriers between the Cu2O film layer and the BiFeO3 ferroelectric film layer are eliminated through gold nano-rod granules by means of the LSPR effect, absorption of visible light with the wave length ranging from 650 nm-750 nm is strengthened, the Cu2O film layer is protected by the BiFeO3 ferroelectric film layer, residual polarization electric fields are used for eliminatingupwarp barriers on photoelectrode/electrolyte interfaces, the water photolysis efficiency and the hydrogen production efficiency are improved, the light current density reaches 91 microampere/cm<2>, and the threshold voltage relative to a reversible hydrogen electrode reaches 1.01 V.

The invention relates to a method for sintering sodium bismuth titanate-based lead-free piezoelectric ceramics at low temperature. The method comprises the following steps: by taking SrFe0.5Co0.5Oy (y is more than 2 and less than 4) as a sintering aid, batching according to a stoichiometric ratio of a chemical formula (1-x)Bi0.5Na0.5TiO3-xSrFeCo0.5Oy and taking Na2CO3, TiO2, Bi2O3 and SrFeCo0.5Oy as raw materials, performing ball-milling and mixing, drying, molding, and sintering at the temperature of 950-1080 DEG C for 2-4 hours, thereby obtaining the sodium bismuth titanate-based lead-free piezoelectric ceramics, wherein x is equal to 0.00-0.06. A ceramic sample sintered in a range of x=0.00-0.06 has high density, the relative density is larger than 90 percent, the high mechanical quality factor Qm is greater than 217, the high remanent polarization Pr is greater than 26mu C/cm<2>, the piezoelectric constant d33 is greater than 92pC/N and the electromechanical coupling factor kp is greater than 15%, the Curie temperature is larger than 300 DEG C, and the material has good application prospects.