Nd_2O_3掺杂(Sr_(0.9)Ba_(0.1))La_4Ti_4O_(15)陶瓷的结构及微波性能

采用传统的固相反应法制备(Sr_(0.9)Ba_(0.1))La_4Ti_4O_(15)+x%Nd_2O_3(质量分数0≤x≤8,BSN)系微波介质陶瓷,并对其物相组成、晶体结构及微波介电性能进行分析。研究结果表明,Nd_2O_3含量的增加降低了BSN陶瓷的烧结温度,陶瓷的主晶相为SrLa_4Ti_4O_(15)相,并伴随有少量第二相La_2TiO_5的生成。在微波频率下,随着Nd_2O_3含量的增加,BSN陶瓷的介电常数及谐振频率温度系数变化小,品质因数与频率之积(Q×f)值提高,优化出掺杂4%Nd_2O_3的(Sr_(0.9)Ba_(0.1))La_4Ti_4O_(15)陶瓷具有最佳微波介电性能:εr=43.2,Q×f=42 015 GHz(6.024 GHz),τf=-9.6μ℃-1。     

CuO/CeO_2共掺杂Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_3无铅压电陶瓷性能研究

采用固相反应法制备了CuO、CeO2共掺杂Ba0.85Ca0.15Zr0.1Ti0.9O3(BCZT)无铅压电陶瓷,研究了CuO的掺杂量对所制陶瓷晶体结构、压电及介电性能的影响。结果表明:CuO的加入,进一步降低了预先经0.05%(质量分数)CeO2掺杂的BCZT陶瓷的烧结温度;在1 250℃烧结时,仍可获得纯钙钛矿结构的BCZT陶瓷。当CuO掺杂量为质量分数0.2%时,所制BCZT陶瓷具有最佳的压电性能:d33=370 pC/N,tC约为93℃,tanδ=0.0147。     

(Ba_(0.85)Ca_(0.15))(Zr_(0.1)Ti_(0.9))O_3-(Ba_(0.85)Ca_(0.15))TiO_3无铅压电陶瓷的结构与性能

采用流延叠层成型工艺制备了(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3-5%(Ba0.85Ca0.15)TiO3(BCZT-5%BCT)无铅压电陶瓷,研究了BCZT-5%BCT陶瓷的微观组织结构对电性能的影响规律,研究表明,BCZT-5%BCT陶瓷的晶粒尺寸对其压电、介电与铁电性能影响显著,在1 500℃下烧结时,BCZT-5%BCT陶瓷的晶粒尺寸随烧结保温时间的增加呈现先增大后减小的趋势,烧结保温时间为8h的样品中晶粒尺寸最大,此时BCZT-5%BCT陶瓷的压电与铁电性能最优,即压电常数(d33)约为218pC/N,剩余极化强度2Pr约为30.48μC/cm2,介电常数(εr)约为1 617,介电损耗(tanδ)约为0.037,居里温度(TC)约为90.6℃。     

Sb_2O_3掺杂Ba(Ti_(0.91)Zr_(0.09))O_3陶瓷的结构与性能

采用固相反应法制备了Sb2O3掺杂的Ba(Ti0.91Zr0.09)O3陶瓷,研究了Sb2O3掺杂量(x(Sb2O3)为0.5%～5.0%)对陶瓷晶相结构及介电性能的影响,分析了陶瓷电滞回线变化的原因。结果表明:Sb3+进入了Ba(Ti0.91Zr0.09)O3陶瓷晶格,引起晶格畸变,且无第二相出现。随着Sb2O3掺杂量的增加,陶瓷晶粒逐渐变小变均匀,tanδ减小。Sb2O3掺杂的Ba(Ti0.91Zr0.09)O3陶瓷为弥散相变铁电体,在x(Sb2O3)为3.0%处弥散程度最小。     

La2O3对Ba0.92Sr0.08Ti0.9Sn0.1O3介质瓷结构及性能的影响

以碳酸钡、碳酸锶、二氧化锡和二氧化钛等为原料,La2O3为掺杂剂,在不同温度下烧结,制得了Ba0.92Sr0.08Ti0.9Sn0.1O3(BSTS)系介质瓷.XRD结果表明,所有的BSTS试样都形成了单一的钙钛矿结构晶相,通过SEM分析了La2O3对试样的微观形貌的影响,发现La2O3的加入可有效地抑制晶粒的尺寸.测试了在1 kHz频率条件下试样的电容量C、介质损耗因数D和-25～+95 ℃试样的C和D,得到了试样的居里温度TC及相对介电常数εr随温度的变化曲线.结果表明,在室温下,试样的εr随着La2O3加入量的增加,呈一直减小的趋势,介电损耗tan δ随着La2O3加入量的增加,则呈先减小后增加的趋势,TC随着La2O3加入量的增加逐渐向低温区移动,介电常数变化率Δε/ε则随着La2O3加入量的增加而逐渐下降.最终得到烧结温度为1 340 ℃,x(La2O3)=0.6%的Ba0.92Sr0.08Ti0.9Sn0.1O3介质瓷的εr最大值为3 825,tan δ最小值为20×10-4,Δε/ε为25.9%( 25 ～85 ℃).     

CuO掺杂对Ba(Ti_(0.91)Zr_(0.09))O_3陶瓷介电性能的影响

采用固相反应法制备了CuO掺杂的Ba(Ti0.91Zr0.09)O3陶瓷,借助XRD、SEM、Agilent4284A测试仪,研究了CuO掺杂对Ba(Ti0.91Zr0.09)O3陶瓷的结构及介电性能的影响.结果表明,CuO具有细化陶瓷晶粒的作用.随着CuO掺杂量的增加,Ba(Ti0.91Zr0.09)O3陶瓷的斜方-四方相变峰出现介电弛豫现象,相变点处的介电常数增加,并且居里峰出现相变弥散现象.当w(CuO)=0.38%时,斜方-四方相变峰的弛豫程度最大.     

La0.9Sr0.1MnO3/Si体系界面的电子显微学研究

本文利用透射电子显微术,研究了通过激光分子束外延方法在Si基体上生长的La0.9Sr0.1MnO3功能薄膜的显微结构特征及界面处的微区成分分布规律.结果表明,在Si基体上生长的La0.9Sr0.1MnO3薄膜由单相多晶体构成.这些多晶体颗粒以柱状结构生长,柱状晶垂直于界面并一直贯穿整个LSMO薄膜.La0.9Sr0.1MnO3薄膜具有正交点阵结构,其颗粒大小为10 nm～20 nm.在LSMO/Si的界面处发现了由化学反应引起的两个纳米尺度的非晶层.     

缓冲层厚度对透明导电薄膜ZnO∶Zr性能的影响(英文)

利用直流磁控溅射法在有ZnO∶Zr缓冲层的水冷玻璃衬底上成功制备出了ZnO∶Zr透明导电薄膜,缓冲层的厚度介于35～208nm。利用XRD、SEM、四探针测试仪和紫外-可见分光光度计研究ZnO∶Zr薄膜的结构、形貌、电光性能。结果表明,薄膜的颗粒尺寸和电阻率对缓冲层厚度具有较强的依赖性。当缓冲层厚度从35nm增加到103nm时,薄膜的颗粒尺寸增大,电阻率减小。而当缓冲层厚度从103nm增加到208nm时,薄膜的颗粒尺寸减小,电阻率增大。当缓冲厚度为103nm时,薄膜的电阻率最小为2.96×10^-3Ω.cm,远小于没有缓冲层时的12.9×10^-3Ω.cm。实验结果表明,在沉积薄膜之前先沉积一层适当的缓冲层是提高ZnO∶Zr薄膜质量的一种有效方法。     

缓冲层厚度对透明导电薄膜ZnO:Zr性能的影响

利用直流磁控溅射法在有ZnO:Zr缓冲层的水冷玻璃衬底上成功制备出了ZnO:Zr透明导电薄膜,缓冲层的厚度介于35～208 nm.利用XRD、SEM、四探针测试仪和紫外-可见分光光度计研究ZnO:Zr薄膜的结构、形貌、电光性能.结果表明,薄膜的颗粒尺寸和电阻率对缓冲层厚度具有较强的依赖性.当缓冲层厚度从35 nm增加到103 nm时,薄膜的颗粒尺寸增大,电阻率减小.而当缓冲层厚度从103 nm增加到208 nm时,薄膜的颗粒尺寸减小,电阻率增大.当缓冲厚度为103 nm时,薄膜的电阻率最小为2.96×10-3 Ω·cm,远小于没有缓冲层时的12.9×10-3 Ω·cm.实验结果表明,在沉积薄膜之前先沉积一层适当的缓冲层是提高ZnO:Zr薄膜质量的一种有效方法.     

MoO3掺杂Ba0.98Bi0.02(Ti0.9Zr0.1)O3陶瓷的介电性能研究

采用固相反应法制备了Ba<,0.98>Bi<,0.02>(Ti<,0.9>Zr<,0.1>)<,1-x>Mo<,x>O<,3>(x=0,0.01,0.03,0.05)陶瓷,研究了MoO<,3>掺杂对Ba<,0.98>Bi<,0.02>(Ti<,0.9>Zr<,0.1>)O<,3>陶瓷的相结构、表面形貌和介电性能的影响....     

掺杂Y2O3对Ba0．92Sr0．08Ti0．9Sn0．1O3介质瓷性能的影响

以BaCO3、SrCO3、SnO2和TiO2等为原料,Y2O3为掺杂剂,在不同温度下烧结,制得了Ba0.92Sr0.08Ti0.9Sn0.1O3系介质瓷,通过SEM分析了Y2O3对试样的微观形貌的影响,测试了试样在1 kHz频率条件下试样的电容量C、介质损耗因数D和-25~ 95℃试样的C和D,得到了试样在1 kHz频率下的居里温度TC及介电常数rε和介电损耗tanδ随温度的变化曲线。结果表明,在室温下,试样的rεt、anδ及介电常数变化率Δε/ε随着Y2O3加入量的增加,都是呈现先减小后增加的趋势;随着烧结温度的升高,rε呈上升趋势而tanδ呈下降趋势。最终得到了烧结温度为1 340℃,加入Y2O3摩尔分数为0.5%时,rε达最大值(3 774),tanδ达最小值(28×10-4),介电常数变化率为22.91%(25~85℃)的Ba0.92Sr0.08Ti0.9Sn0.1O3介质瓷。     

不同晶粒尺寸钛锡酸钡陶瓷的烧结及介电性能

利用溶胶包覆和高能球磨的方法,经传统的陶瓷工艺,得到相对密度在95%以上,晶粒尺寸在0.36~23μm之间的Ba(Ti0.9Sn0.1)O3钛锡酸钡陶瓷。发现用溶胶包覆粉体的方法,可以阻止烧结过程中晶粒的异常长大,并且降低陶瓷的烧结温度。对样品介电性能进行了研究,发现随着晶粒尺寸的减小,Ba(Ti0.9Sn0.1)O3陶瓷表现出相对介电常数峰值对应的温度(tm)向低温方向移动,相变弥散程度增加,室温(25℃)相对介电常数先增大后减小的规律。     

Sol-Gel processing of Nb-doped Pb(Zr,Ti)O3 thin films for ferroelectric memory applications

The ferroelectric properties of Nb-doped PZT thin films prepared by a sol-gel method were evaluated relative to memory device application requirements. Within the range of 0 to 4 mol %, Nb-doping of PZT compositions near the morphotropic phase boundary region (i.e. PZT 53/47) enhanced overall ferroelectric properties by reducing the te-tragonal distortion of the unit cell. A 4 mol % Nb-doped PZT 53/47 thin film (0.26 μm) had a coercivity of 8 V/ μm, a remanence ratio of 0.54, a switchable polarization of 45 μC/cm², and a specific resistivity of 3 x 10⁹ Ω-cm. Nb-doping levels in excess of 5 mol had a detrimental effect on the resulting thin film ferroelectric properties. X-ray diffraction (XRD) analysis of highly doped films showed development of a significant PbO phase accompanied by diffraction line broadening of the perovskite phase. As such, it was postulated that the creation of excessive lead vacancies in the PNZT lattice resulted in PbO accumulation at the grain boundaries which impeded grain growth, and hence, adversely affected ferroelectric switching performance. The fatigue performance of the sol-gel derived thin film capacitor system was a function of switching voltage. At switching fields sufficient to saturate the polarization, the endurance of the thin film capacitor was greater than 10⁹ cycles. Cycling with lower fields reduced endurance values, but in all cases, the switchable polarization decreased linearly with the logarithm of cycles. Nb-doping did not have a significant effect on the fatigue performance.     

Fabrication of Microcantilever Sensors Actuated by Piezoelectric Pb(Zr0.52Ti0.48)O3 Thick Films and Determination of Their Electromechanical Characteristics

The integration and the device realization of Pb(Zr, Ti)O₃ (PZT) thick films on Si substrates are known to be extremely difficult because the processing temperature of the PZT thick film is close to the melting point of Si. However, PZT thick‐film devices on Si warrant attention as they are appropriate for biological transducers; they generate large actuating forces and have a relatively high sensitivity for mass detection, especially in liquids. In this study, Pb(Zr_0.52Ti_0.48)O₃ thick‐film cantilever devices are successfully fabricated on a Pt/TiO₂/SiN_x/Si substrate using a screen‐printing method and microelectromechanical systems (MEMS) process. Elastic and electromechanical properties such as the Young's modulus and transverse piezoelectric coefficient are determined from microstructural and electrical analyses for further mechanical study. The calculated Young's modulus of the thick film, 53.9 ± 3.85 GPa, corresponds to the resonant frequency obtained from the measured harmonic oscillation response. The transverse piezoelectric constant, d₃₁, of –20.7 to –18.8 pC N^–1 is comparable to that of a dense thin film. These values promise the possibility of determining the resonance properties of a thick‐film cantilever by designing its structure and then simulating the harmonic oscillation response. Using the PZT thick‐film cantilever, a strong harmonic oscillation with a quality (Q) factor of about 23 is demonstrated in water. The observation of strong harmonic oscillation in liquid implies the feasibility of precise real‐time recognition of biomolecules using PZT thick‐film cantilevers.