CN101034144B - Full-automatic measurement device for magnetoelectric properties of magnetoelectric material and measuring method thereof - Google Patents

Abstract

This invention belongs to magnetic electricity material domain, which conretely relates to using fictitious multichannel phase-locking enlarging principle to implement test material magnetic electricity function method and device of computer control. This invention make phase-locking amplifier fictitious, which is that computer software implements function of phase-locking amplifier. It is very convenient to carry out phase-locking agnification process for random multipath signal by using fictitious phase-locking amplifier. Therefore, it not only precisely automatically survey dE and dH, improve magnetic electricity function measurement precision, but also work frequency limit is boosted a lot compared to hardware phase-locking amplifier, meanwhile decrease manufacture cost of magnetic electricity measuring device. This invention also combines control and measurement of apposition cocurrent offset magnetic field to boost automaticity of magnetic electricity measuring device, thereby improve precision and efficiency of magnetic electricity measurement.

Description

A kind of full-automatic magnetoelectric properties of magnetoelectric material measurement mechanism and measuring method thereof

Technical field

The invention belongs to the magnetoelectric material field, relate to the measuring technique of magnetoelectric properties of magnetoelectric material, be specifically related to utilize the device and the measuring method thereof of the measurement magnetoelectric properties of magnetoelectric material of all computer control that the phase-locked amplification principle of virtual hyperchannel realizes.

Background technology

Magnetic electricity performance is meant the externally dielectric polarization brought out of magnetic field of material, or the magnetization brought out of external electric field.Usually said magnetic electricity performance is not having all to be meant the induced by magnetic field dielectric polarization under the situation about specifying.Magnetic electricity performance can have broad application prospects in the components and parts at many high-performance magnetism electric works, and particularly, it can be applicable in the numerous areas such as detection of magnetic field, conductor magneto-electric energy exchange, information stores and driving.The measurement of material magnetic electricity performance then is a most key link in magnetoelectric material research and development and the application process.What the index of sign magnetic electricity performance was commonly used is the magnetoelectricity voltage coefficient, is defined as α _ME=dV/ (tdH), wherein dH is the interchange differential magnetic field that superposes on the direct current biasing magnetic field, and dV is the voltage that the sample two ends produce under the differential the action of a magnetic field, and t is a sample thickness.

Usually test condition all is under kHz or MHz frequency, at this frequency band, the differential magnetic field that is produced by helmholtz coil all is very small usually, that is to say by the electric current of helmholtz coil very faintly, and the voltage that the sample two ends produce also is very small.Therefore, the measurement of the magneto-electric response signal of magnetoelectric material relates to Testing of Feeble Signals, and accurate magnetoelectricity measuring equipment must be used lock-in amplifier, because lock-in amplifier price height, thereby cause domestic and international existing magnetoelectricity measuring equipment cost costliness at present.On the other hand, by α _ME=dV/ (tdH) as can be seen, the acquisition of magnetic electricity performance need be measured dV and dH simultaneously, but every of common commercial lock-in amplifier can only carry out phase-locked processing and amplifying to the signal of a passage, can't measure dV and dH simultaneously, so at present domestic and international common way is only to measure dV and nominal dH is fixed [1-2].When actual measurement, especially when the frequency change of AC magnetic field dH being completely fixed is not allow readily accessiblely, therefore can't do accurate dynamic monitoring to magnetic field, thereby also just can't obtain magnetic electricity performance accurately.The use operating frequency range of lock-in amplifier also is the important indicator that embodies magnetoelectricity test macro measurement capability, the frequency of operation of general lock-in amplifier is all below 200kHz, if test condition has exceeded this operating frequency range, use lock-in amplifier just can't satisfy the needs of test so, test can't be carried out.If the test frequency of the equipment of expansion then needs more expensive wideband lock-in amplifier, this will further improve equipment cost undoubtedly.In addition, magnetic electricity performance must be measured [1-2] with the variation and the magnetic electricity performance of external dc bias magnetic field respectively with the variation that adds the AC magnetic field frequency, can't obtain magnetic electricity performance simultaneously with external dc bias magnetic field and the variation that adds the AC magnetic field frequency.This shows, present domestic and international existing magnetoelectricity measuring equipment cost costliness, precision, upper frequency limit are not high enough, and the measuring process automaticity is also in urgent need to be improved.

[1]M.Mahesh?Kumar?et?al，An?experimental?setup?for?dynamic?measurement?ofmagnetoelectric?effect，Bull.Mater.Sci.，21(3)，251-255(1998)

[2]Shuxiang?Dong，Jie-Fang?Li，and?D.Viehland，Characterization?of?magnetoelectriclaminate?composites?operated?in?longitudinal-transverse?and?transverse-transverse?modes，J.Appl.Phys.，95(5)，2625-2630(2004)

Summary of the invention

The objective of the invention is to overcome existing surveying instrument cost height, the drawback that measuring accuracy, upper frequency limit and automaticity are not high, for this reason that lock-in amplifier is virtual, the functional utilization computer software that is about to lock-in amplifier is realized, because lock-in amplifier is virtual, can realize very easily multichannel signal is carried out phase-locked processing and amplifying.So, not only can simultaneously accurate kinetic measurement dV and dH, improved the magnetic electricity performance measuring accuracy, and compare the hardware lock-in amplifier frequency of operation upper limit and be greatly improved, reduce the manufacturing cost of magnetoelectricity measuring equipment simultaneously, in addition, the present invention further improves the automaticity of magnetoelectricity measuring equipment in conjunction with the control and the measurement of external dc bias magnetic field, thereby improves magnetoelectricity measuring accuracy and efficient.

A kind of full-automatic magnetoelectric properties of magnetoelectric material measurement mechanism comprises electromagnet 1, helmholtz coil 2, teslameter 3, direct supply 4, specimen 5, computing machine 8, difference instrument 11, data acquisition front 12, signal generator 13, power amplifier 14.But data acquisition front is the A/D card or the digital oscilloscope of a multichannel synchronized sampling, and computing machine 8 is provided with record cell 7, virtual signal generation control module 9, the correlator 10 of closed-loop control unit, virtual magnetic field 6, magneto-electric coupled performance.

Electromagnet 1 is used for producing direct current biasing magnetic field; The helmholtz coil of putting in the middle of D.C. magnetic field 2 is used for producing AC magnetic field; Add biased magnetic field strength and read and send into computing machine by teslameter 3.Direct supply 4 controls add bias magnetic field; Closed-loop control unit, virtual magnetic field 6 in the computing machine can read in from the intensity in the 3 direct current biasing magnetic fields of transmitting; The control signal of transmitting direct current biasing magnetic field by the D/A card arrives power supply 4.Virtual signal generation control module 9 in the computing machine 8 offers helmholtz coil 2 as its drive signal after by signal generator 13 signal being amplified through power amplifier 14.The intensity of alternating magnetic field converts voltage signal input data acquisition front 12 to by the resistance R that is connected in the helmholtz coil 2.The magneto-electric response signal that produces on the testing sample 5 in the magnetic field is connected to difference instrument 11 by two coaxial cables; The input signal cable of difference instrument 11 improves signal to noise ratio (S/N ratio) by floating ground connection, and its output is received on the data acquisition front 12.Virtual signal generation control module 9, correlator 10, data acquisition front 12 are three major parts of virtual lock-in amplifier.Correlator 10 is core components of virtual hyperchannel lock-in amplifier, and the reference signal that the magneto-electric response signal that utilizes data acquisition front 12 input and the signal and the signal generation control module 9 of AC magnetic field intensity are imported carries out the record cell 7 that correlation computations obtains information such as magneto-electric coupled intensity and phase differential and the result outputed to magneto-electric coupled performance.The direct current biasing magnitude of field intensity of self-magnetic field control module 6 inputs can dynamically be noted down in magneto-electric coupled performance inventory unit 7; And the information of magneto-electric response intensity of importing into by correlator 10 and phase lag and other experiment informations, thereby finish the measurement of continuous full-automation.

The use prerequisite of correlator is that measured signal is the faint sinusoidal signal with some cycles among the present invention, its mathematical form is s (t)=Asin (ω t+ φ), and in the measuring-signal of data acquisition front, be mixed with noise n (t), i.e. measuring-signal Vs (t)=s (t)+n (t).Reference signal in the correlator is that two amplitudes are 1, phase place differ sinusoidal signal Vr (the t)=sin (ω t) of pi/2 and Vr ' (t)=sin (ω t+ pi/2).Find the solution the simultaneous equations of discrete signal cross correlation function, can obtain $\mathrm{\φ}=\arctan \left\{\underset{k}{\overset{N}{\mathrm{\Σ}}}\right[\mathrm{Vs}\left(k\right)V{r}^{\′}\left(k\right)/\underset{k}{\overset{N}{\mathrm{\Σ}}}\left[\mathrm{Vs}\left(k\right)\mathrm{Vr}\left(k\right)\right]\},$ $A=2\underset{k}{\overset{N}{\mathrm{\Σ}}}\left[\mathrm{Vs}\left(k\right)\mathrm{Vr}\left(k\right)\right]/\cos \mathrm{\φ},$ Wherein N enters the sampled signal of correlator or the discrete sampling point total amount of virtual reference signal.

The phase-locked amplification principle of virtual multichannel that uses among the present invention is synchronous voltage signal dV and field signal dH to be transmitted simultaneously enter correlator, and result of calculation obtains the amplitude A of voltage signal respectively _DEWith phase _DEAmplitude A with field signal _DHWith phase _DH, and then calculate the size of magneto-electric coupled performance and magneto-electric coupled amplitude α _MEAnd phase difference _ME

Because the D.C. magnetic field that power supply 4 produces can not change in time, so earlier magnetic field is demarcated before the magnetoelectricity measurement, generated form.When loading the direct current biasing magnetic field of certain strength, needs directly set D.C. magnetic field by tabling look-up.The each magnetic electricity performance of real-time follow-up is measured pairing instantaneous direct current biasing magnetic field value constantly in dynamic magnetic electrical measurement process, and it and the direct current biasing magnetic field value of setting differ less than 5%.

The virtual phase-locked amplification principle that the present invention uses is that the AC signal of magneto-electric response is carried out phase sensitive detection, promptly utilize measured signal and reference signal to have same frequency and certain phase relation, only in the measured signal and that part of component of signal of reference signal same frequency response is arranged, that part of noise of being used as with the reference signal different frequency in the measured signal then is suppressed, and therefore can improve the signal to noise ratio (S/N ratio) that magnetoelectricity is measured significantly.

The magnetoelectricity measurement mechanism that the phase-locked amplification principle of virtual hyperchannel of the present invention is built has following technique effect:

(1) synchronous dynamic is measured two parameter dV and the dH in the magnetoelectricity voltage coefficient formula accurately, thereby has improved the measuring accuracy of magnetic electricity performance, and this is that other magnetoelectricity measurement mechanisms are not available.

(2) owing to adopted virtual phase lock amplifying technology, quite big to the control degrees of freedom of the whole process of phase-locked amplification, thereby increase the automatic control level of magnetoelectricity measuring equipment.Both at home and abroad in other magnetoelectricity measuring equipments as yet the someone introduce virtual phase lock amplifying technology.

(3) do not use real lock-in amplifier among the present invention, thereby greatly reduce the cost of magnetoelectricity measuring equipment.

(4) be virtual lock-in amplifier owing to what use, its frequency of operation will be expanded greatly, not be subjected to the restriction of hardware lock-in amplifier frequency of operation.

(5) virtual lock-in amplifier is gathered simultaneously and is calculated signal taking place and producing signal, can directly obtain both phase places, thereby provide possibility to the research of phase place.

(6) the present invention can full automaticly measure the 3-D view of material magnetic electricity performance with external dc bias magnetic field and alternating magnetic field frequency change with the closed-loop control system combination of virtual hyperchannel lock-in amplifier and virtual D.C. magnetic field.The material magnetic electricity performance with external dc bias magnetic field and the 3-D view that adds the AC magnetic field frequency change up to the present at home and abroad as yet the someone can measure.

Description of drawings

Fig. 1 is the structural representation that utilizes the full-automatic magnetoelectricity measurement mechanism of the phase-locked amplification principle of virtual hyperchannel of the present invention.

Fig. 2 is the measurement curve that Ni/PZT/Ni laminar composite transverse magnetic electric coupling intensity is changed with the external dc bias magnetic field of the present invention.

Fig. 3 is that the phase lag to Ni/PZT/Ni laminar composite transverse magnetic electric coupling intensity and magneto-electric response of the present invention is with the variation that adds the AC magnetic field frequency.

Fig. 4 is the localized variation of Fig. 3.

Fig. 5 is the magneto-electric coupled intensity to the Ni/PZT/Ni laminar composite of the present invention with adding bias magnetic field and adding the 3-D view of AC magnetic field frequency change.

Fig. 6 is the phase lag to Ni/PZT/Ni laminar composite magneto-electric response of the present invention with adding bias magnetic field and adding the 3-D view of AC magnetic field frequency change.

Embodiment

Be described further below by embodiment and accompanying drawing.

Embodiment 1, and what typical specimen 5 adopted is the Ni/PZT/Ni laminar composite.Measuring N i/PZT/Ni laminar composite transverse magnetic electric coupling coefficient α _{ME, 31}And the magnetoelectricity respective phase lags behind.

(1) according to the principle assembling instrument of Fig. 1, wherein produces the sensing resistor R=10 Ω in magnetic field.Data acquisition front 12 is Rigol DS5062CA type oscillographs; Signal generator 13 is Agilent33220A; The direct current biasing field system adopts WWL-LSX21 type three-phase dc stabilized voltage supply and SB175 type electromagnet; Teslameter 3 uses HT100; (40GB WindowsXP) installs the development platform of Labview8.0 assessment version as control program for 1.6GHz, 256MB at computing machine.Under Labview, write corresponding measurement control software according to above-mentioned principle.

(2) Ce Shi sample is to be of a size of the compound square sheets of Ni/PZT/Ni stratiform of electroplated Ni on the PZT ferroelectric ceramics of 25mm * 25mm * 0.8mm, and wherein the thickness of Ni, PZT and Ni is respectively 0.4mm, 0.8mm and 0.4mm.Coaxial cable is drawn by the magnetic field of putting into shown in Figure 1 in the two sides of magnetoelectricity composite sheet, and placement direction guarantees that the length of side direction of D.C. magnetic field direction, AC magnetic field direction and square sheets is parallel.Because magnetic direction in facing and consistent with the square length of side, is designated as 1 direction, because it is the direction of vertical plate that magnetic is given birth to the electric field outbound course, be defined as 3 directions again, so magneto-electric coupled intensity note is made α _{ME, 31}

(3) check that all power leads and signal wire line begin to power up after errorless.The driving signal frequency of the AC magnetic field that will export from signal generator 13 is set at 1kHz, and amplitude is set at 1V, and remains unchanged.Begin to increase gradually direct current biasing magnetic field then, observe magnetoelectricity output simultaneously, as shown in Figure 2, the direct current biasing magnetic field value H of correspondence when peak value appears in magnetoelectricity as can be seen _D=150 Oe.

(4) fixing direct current biasing magnetic field H _DThe amplitude 1V of the output AC voltage of=150 Oe and signal generator 13 is constant, only changes the frequency of signal generator 13 output AC voltages, and the operation control program writes down the amplitude and the phase lag value of magneto-electric response output automatically, obtains Fig. 3.It is that the phase lag of Ni/PZT/Ni laminar composite transverse magnetic electric coupling intensity and magneto-electric response is with the measurement curve that adds the AC magnetic field frequency change.The transverse magnetic of Ni/PZT/Ni laminar composite is given birth to the electric field factor alpha as can be seen _{ME, 31}Maximal value is 41.5V/cm Oe, appears at 85.3kHz.Two other resonance peak is resonance peaks respectively at 59.5kHz and 73.5kHz though can not differentiate them on intensity, according to the phase lag curve of magneto-electric response, can confirm that they are two resonance peaks.

(5) position of highest peak value appears in analysis chart 3 magnetoelectricity output intensities, keep other condition constant, near the peak value frequency is carried out fine scanning, obtain Fig. 4, it be the Ni/PZT/Ni laminar composite near resonant frequency transverse magnetic electric coupling intensity and the phase lag of magneto-electric response with the measurement curve that adds the AC magnetic field frequency change.The size that fine scanning by near the frequency strong resonance peak can obtain more accurate resonant frequency is at 85.25kHz, corresponding α _{ME, 31}Maximal value also increases to 43.2V/cm Oe.

Embodiment 2, and the transverse magnetic of measuring N i/PZT/Ni laminar composite is given birth to the electric field factor alpha _{ME, 31}And the phase lag of magneto-electric response is with adding bias magnetic field and adding the 3-D view that the AC magnetic field frequency changes.

(1) in order to increase the magnetic field automatic control module, the control interface of AD/DA card (AC6632 and AC6682) as direct current biasing magnetic field is installed in the PCI of computing machine slot in addition, hardware and software in the measuring system is expanded accordingly.All the other are with the step 1 in the example 1

(2) Ce Shi sample is with the step 2 in the example 1.

(3) amplitude of the output AC voltage of fixed signal generator 13 is 1V, remain unchanged, change the frequency of signal generator 13 output AC voltages and the size of direct current biasing magnetic field (seeing 1 among Fig. 1) simultaneously, the operation control program, automatically the amplitude and the phase lag value of the output of record record magneto-electric response obtain Fig. 5 and Fig. 6.They are respectively that the phase lag of the magneto-electric coupled intensity of Ni/PZT/Ni laminar composite and response is with adding bias magnetic field and adding the 3-D view that the AC magnetic field frequency changes.As can be seen from Figure 5, the transverse magnetic electric coupling performance of Ni/PZT/Ni laminar composite is symmetrical distribution with bias magnetic field substantially at positive and negative two ends, and on certain bias magnetic field absolute value, reaching peak value, the magneto-electric coupled performance of this reflection Ni/PZT/Ni laminar composite derives from the magnetostriction performance of Ni layer.In addition, the frequency of AC magnetic field significantly is better than direct current biasing magnetic field to magneto-electric coupled Effect on Performance degree.Plant as can be seen from Fig. 6, three the frequency interphases corresponding with Fig. 3 are 59.5kHz, 73.5kHz and 85kHz, and the reflection resonance characteristics does not change with bias magnetic field.The interphase that also has a direct current biasing magnetic field to introduce simultaneously on Fig. 6 embodies magneto-electric coupled sign change.

Claims (3)

1. a full-automatic magnetoelectric properties of magnetoelectric material measurement mechanism is characterized by measurement mechanism and comprises electromagnet (1), helmholtz coil (2), teslameter (3), direct supply (4), specimen (5), computing machine (8), difference instrument (11), data acquisition front (12), signal generator (13), power amplifier (14); But data acquisition front is the A/D card or the digital oscilloscope of a multichannel synchronized sampling, and computing machine (8) is provided with record cell (7), virtual signal generation control module (9), the correlator (10) of closed-loop control unit, virtual magnetic field (6), magneto-electric coupled performance; Electromagnet (1) is used for producing direct current biasing magnetic field; The helmholtz coil of putting in the middle of D.C. magnetic field (2) is used for producing AC magnetic field; Add biased magnetic field strength and read and send into computing machine by teslameter (3); Correlator (10) utilizes the magneto-electric response signal of data acquisition front (12) input and the signal of AC magnetic field intensity and the reference signal of virtual signal generation control module (9) input to carry out the record cell (7) that correlation computations obtains magneto-electric coupled intensity and phase information and the result outputed to magneto-electric coupled performance; Magneto-electric coupled performance inventory unit (7) can dynamically record the information that the magneto-electric response intensity imported into from the DC bias magnetic field intensity size of fictitious magnetic field Closed Loop Control Unit (6) input and by correlator (10) and phase place lag behind, thereby finishes the measurement of continuous full-automation.

2. a full-automatic magnetoelectric properties of magnetoelectric material measuring method is characterized in that adding bias magnetic field with direct supply (4) control; Closed-loop control unit, virtual magnetic field (6) in the computing machine reads in from the intensity in the direct current biasing magnetic field that teslameter (3) transmits, and the control signal of transmitting direct current biasing magnetic field by the D/A card arrives direct supply (4); Virtual signal generation control module (9) in the computing machine (8) offers helmholtz coil (2) as its drive signal after by signal generator (13) signal being amplified through power amplifier (14); The intensity of alternating magnetic field converts voltage signal input data acquisition front (12) to by the resistance R that is connected in the helmholtz coil (2); Testing sample in the magnetic field (5) is gone up the magneto-electric response signal that produces and is connected to difference instrument (11) by two coaxial cables; The input signal cable of difference instrument (11) improves signal to noise ratio (S/N ratio) by floating ground connection, its output is received on the data acquisition front (12), correlator (10) utilizes the magneto-electric response signal of data acquisition front (12) input and the signal of AC magnetic field intensity and the reference signal of virtual signal generation control module (9) input to carry out the record cell (7) that correlation computations obtains magneto-electric coupled intensity and phase information and the result outputed to magneto-electric coupled performance, magneto-electric coupled performance inventory unit (7) can dynamically write down the direct current biasing magnitude of field intensity of closed-loop control unit, self-virtualizing magnetic field (6) input and the magneto-electric response intensity of being imported into by correlator (10) and the information of phase lag, thereby finishes the measurement of continuous full-automation.

3. as a kind of full-automatic magnetoelectric properties of magnetoelectric material measuring method as described in the claim 2, the use prerequisite that it is characterized in that correlator is that measured signal is the faint sinusoidal signal with some cycles, its mathematical form is s (t)=Asin (ω t+ φ), and in the measuring-signal of data acquisition front, be mixed with noise n (t), i.e. measuring-signal Vs (t)=s (t)+n (t); Reference signal in the correlator is that two amplitudes are 1, phase place differ sinusoidal signal Vr (the t)=sin (ω t) of pi/2 and Vr ' (t)=sin (ω t+ pi/2); Find the solution the simultaneous equations of discrete signal cross correlation function, obtain Wherein N enters the sampled signal of correlator or the discrete sampling point total amount of virtual reference signal.

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