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Surface acoustic wave (SAW) properties at the x-cut of relaxor-based 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN- 33%PT) ferroelectric single crystals are analyzed theoretically when poled along the [001]c cubic direction. It can be found that PMN-33%PT single crystal is a kind of material with a low phase velocity and high electromechanical coupling coefficient, and the single crystal possesses some cuts with zero power flow angle. The results are based on the material parameters at room temperature. The conclusions provide device designers with a few ideal cuts of PMN-33%PT single crystals. Moreover, choosing an optimal cut will dramatically improve the performance of SAW devices, and corresponding results for crystal systems working at other temperatures could also be figured out by employing the method.  相似文献   
2.
We report that the measurements of the pyroelectric current of the pre-poled [111]-oriented 0.955 Pb(Zn1/3Nb2/3) O3-0.045 PbTiO3 (PZN-4.5%PT) single crystals can shed some light on the phase transition and spontaneous polarization characters of this material in a similar way to measures of remanent polarization and dielectric properties. The pyroelectric current is measured and the corresponding spontaneous polarization is calculated as a function of temperature with various poling fields added during cooling the sample from 200℃ to room temperature. Critical electric field of 0.061 k V/cm is found to be essential to induce the intermediate ferroelectric orthorhombic phase between the ferroelectric rhombohedral and tetragonal phases. Below the critical field, the polarization increases almost linearly with the increase of poling field. At the critical field, the polarization at 30OC increases abruptly from 14μC/cm^2 for a poling field of O.06kV/cm to 29.5μC/cm^2 for a poling field of 0.061 kV/cm, and afterwards, increases slowly and saturates to 31 μC/cm^2 for poling fields beyond 0.55 kV/cm.  相似文献   
3.
孙恩伟  张锐  赵欣  曹文武 《光子学报》2009,38(6):1442-1445
以波长为632.8 nm的He-Ne激光作为光源,研究了三方相弛豫铁电单晶0.93Pb(Zn1/3Nb2/3)O3-0.07PbTiO3在室温下的折射率和线性电光性质.通过测量晶体的布儒斯特角,确定了单晶的两个主轴折射率:no=2.466,ne=2.488.利用改进的马赫-泽德尔干涉法测量了单晶的线性电光系数:r33=71 pm/V,r13=4 pm/V.计算得到有效电光系数rc=67 pm/V及半波电压Vπ=610 V.单晶优异的电光性能使其在激光调制与偏转领域有着巨大的应用潜力.  相似文献   
4.
Dispersion relations of Love mode acoustic guided 0.33 PT) single crystal with a gold electrode film waves propagation in Pb(Mg1/3 Nb2/3 ) 03-33%PbTiO3 (PMN- are calculated. There is no cross coupling among Love wave modes, which is conducive to eliminating the cross interference between modes. The general formula is derived to precisely measure the thickness of the electrode. More acoustic energy would be concentrated inside the electrode with the increase of film thickness for a given frequency. Compared with the PZT-5 ceramic, [001]c poled PMN- 33%PT single crystal has a slower attenuation of the amplitude of the acoustic guided wave. Therefore, single crystal is extremely suitable for making low loss acoustic wave devices with a high operating frequency.  相似文献   
5.
We have derived a general formula for sensitivity optimization of gravimetric sensors and have used it to design a high sensitivity gravimetric sensor using unidirectional carbon fiber epoxy composite (CFEC) waveguide layer on (1 -x)Pb(Znl/3Nbz/3)O3-xPbTiO3 (PZN-xPT) single crystal substrate with the carbon fibers parallel to the xj and x2 axes, respectively. The normalized maximum sensitivity (|sfm|λ)max exhibits an increasing tendency with the decrease of (h/λ)opt and the maximum sensitivity (|sfm|λ)max increases with the elastic constant c6E6 of the piezoelectric substrate material. For the CFEC/[011]c poled PZN-7%PT single crystal sensor configuration, with the carbon fibers parallel to the xa axis at λ = 24 ktm, the maximum sensitivity |sfm|max can reach as high as 1156 cmZ/g, which is about three times that of a traditional SiO2/ST quartz structure gravimetric sensor. The better design selection is to have the carbon fibers parallel to the direction of propagation of Love wave in order to obtain the best sensitivity.  相似文献   
6.
We have derived a general formula for sensitivity optimization of gravimetric sensors and have used it to design a high sensitivity gravimetric sensor using unidirectional carbon fiber epoxy composite(CFEC) waveguide layer on(1- x)Pb(Zn1/3Nb2/3)O3-xPbTiO3(PZN-xPT) single crystal substrate with the carbon fibers parallel to the x1 and x2axes, respectively. The normalized maximum sensitivity Sfm λ maxexhibits an increasing tendency with the decrease of(h/λ)optand the maximum sensitivity Sfm λ maxincreases with the elastic constant cE66 of the piezoelectric substrate material. For the CFEC/[011]c poled PZN-7%PT single crystal sensor configuration, with the carbon fibers parallel to the x1 axis at λ = 24 μm, the maximum sensitivity Sfm maxcan reach as high as 1156 cm2/g, which is about three times that of a traditional SiO2/ST quartz structure gravimetric sensor. The better design selection is to have the carbon fibers parallel to the direction of propagation of Love wave in order to obtain the best sensitivity.  相似文献   
7.
By taking into account structural transition zones near the lateral and thickness direction edges,this paper uses a modified transverse Ising model to study dielectric properties of a finite size ferroelectric thin film in the framework of the mean-field approximation.The results indicate that the influence of the lateral size on the dielectric susceptibility cannot be neglected and lateral structural transition zones could be a crucial factor that improves the mean susceptibility of the fixed size film.  相似文献   
8.
用Czochralski方法生长出铁电钨青铜型单晶 (Sr1-xBax) 2 NaNb5O15(简称SBNN) ,晶体沿c轴方向生长。正交 四方相的准同型相界 (简称为MPB)存在于x =0 .4 5~ 0 .5 0之间 ;SBNN晶体是不一致熔融的化合物 ,在晶体成长过程中 ,Sr2 的分凝系数比Ba2 的大 ,因此具有高浓度Ba2 的SBNN晶体很难生长。晶体的居里温度是 2 4 3℃ ,在此温度下的相变是弥散的 ,随频率的增加 ,介电常数降低。  相似文献   
9.
Taking into account surface transition layers (STLs), we study the phase transformation and pyroelectric properties of ferroelectric thin films by employing the transverse Ising model (TIM) in the framework of the mean field approximation. The distribution functions representing the intra-layer and inter-layer couplings between the two nearest neighbour pseudo-spins are introduced to characterize STLs. Compared with the results obtained by the traditional treatments for the thin films using only the single surface transition layer (SSL), it is shown that the STL model reflects a more realistic and comprehensive situation of films. The effects of various parameters on the phase transformation properties have shown that STL can make the Curie temperature of the film higher or lower than that of the corresponding Sulk material, and the thickness of STL is a key factor influencing the film properties. For a film with definite thickness, there exists a critical STL thickness at which ferroelectricity will disappear when the intra-layer and inter-layer interactions are weak.  相似文献   
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