CuO掺杂对KNN-LS-BF无铅压电陶瓷性能的影响

采用传统固相合成法和制备工艺,在1040℃制备了{0.996 [0.95( Na0.5 K0.5)NbO3-0.05LiSbO3 ]-0.004FeBiO3}+x mol; CuO(KNN-LS-BF+x mol; CuO)无铅压电陶瓷,研究了CuO掺杂量对陶瓷结构和性能的影响.结果表明,CuO的低温促烧作用明显,微量CuO的掺入并没有改变陶瓷体系的相结构,但对陶瓷的压电和介电性能有明显影响.随CuO掺杂量的增加,陶瓷的d33、kp、εr均是先升高后降低,并在x=0.15时,d33、kp、εr分别达到最大值222 pC/N、0.36、1223.14;Qm也是先升高后降低,不过是在x=0.3时达到了最大值66.02.而tanδ则是先降低,在x=0.45达到最小值2.5;后又开始回升.在x=0.15时,所制备压电陶瓷有最好的综合性能:d33=222pC/N,kp=0.36,εr=1223.14,tanδ=3.3;,Qm =52.27.     

BNT-BKT-BiFeO3无铅压电陶瓷的压电性能和退极化温度

采用传统陶瓷制备方法,制备了系列新型无铅压电陶瓷材料(1-x-y)Bi0.5Na0.5TiO3-xBi0.5K0.5TiO3-yBiFeO3(简写为BNT-BKT-BF-x/y).研究了该体系陶瓷微观结构、压电性能和退极化温度变化规律.结果表明:在所研究的组成范围内,所制备的材料均能够形成纯钙钛矿固溶体,陶瓷三方、四方共存的准同型相界(MPB)成分为x=0.18～0.21,y=0～0.05,在准同型相界成分附近该体系陶瓷压电性能达到最大值:d33=171pC/N,kp=0.366.采用平面机电耦合系数kp和极化相位角θmax与温度的关系来确定退极化温度,得到的结果基本相同,陶瓷的退极化温度随BF含量的增加一直降低,随BKT含量的增加先降低后升高.     

Na0.5Bi0.5TiO3-K0.5Bi0.5TiO3-BaMnO3无铅压电陶瓷的结构与电性能

采用固相法制备了(0.8 -x)Na0.5 Bi0.5TiO3 -0.2K0.5Bi0.5TiO3-xBaMnO3(简称NBT-KBT-BM)无铅压电陶瓷,研究了不同BM含量(x=0,0.25％,0.50％,0.75％,1.00％,1.25％,物质的量分数)样品的物相组成、显微结构及电性能.结果表明:所制备的NBT-KBT-BM陶瓷样品均为单一的钙钛矿结构.与纯NBT-KBT陶瓷相比,掺BM陶瓷的烧结温度降低,相对密度ρr得到提高.随x的增加,材料的压电常数d33、平面机电耦合系数kp与机械品质因子Qm先增大后减小,而介电损耗tanδ以及退极化温度Td一直降低.BM的掺入降低了材料的矫顽场Ec,提高了剩余极化强度Pr,从而增强了铁电性.当x=0.75％时,陶瓷获得最佳性能:d33=167 pC/N,kp=0.269,Qm=133,εr=774,tanδ=2.93％.     

CeO2掺杂KNN-LiNbO3无铅压电陶瓷的压电与介电性能研究

采用传统固相烧结法制备了0.98K0.5Na0.5NbO3-0.02LiNbO3-xCeO2(0.98KNN-0.02LN+xCeO2)无铅压电陶瓷.研究了不同CeO2掺杂含量(x=0、0.01、0.02、0.03、0.04)对0.98KNN-0.02LN陶瓷显微结构和电学性能的影响.研究结果表明:当CeO2掺杂含量从x=0.00到x=0.01和从x=0.02到x=0.03时,样品出现了正交-四方相转变.当x=0.00和x=0.02时,样品都处于正交与四方两相共存状态.CeO2少量掺杂时Ce4+完全进入晶格,表现为"受主"掺杂的特性;而大量CeO2掺杂时,有杂相的生成,主要起到烧结助剂的作用.样品在1080℃下烧结,当掺杂含量为x=0.02时取得最佳的综合性能:d33=104pC/N,Qm=2201,kp=0.24423,εr=804.2,tanδ=8.748;.     

CuO掺杂对KNN-BNZ无铅压电陶瓷性能的影响

采用传统固相反应法制备了0.97K05Na0.5NbO3-0.03Bi0.5Na0.5ZrO3+xmo1; CuO (0.97KNN-0.03BNZ+xCu)无铅压电陶瓷.研究不同CuO掺量(x=0、0.5、1、2、3和4)对0.97KNN-0.03BNZ陶瓷的显微结构和电学性能的影响.结果表明:CuO的掺入使材料出现“硬化”现象,机械品质因数Qm有明显提高,矫顽场显著增大.CuO的掺入量在3;时,样品的综合性能最佳:压电常数(d33)为137 pC/N,机电耦合系数(kp)为0.30,机械品质因数(Qm)为238,介电损耗(tanδ)为1.5;.另外,从SEM图片中可以看出:0.97KNN-0.03BNZ压电陶瓷材料的平均晶粒尺寸随着CuO掺入量的增加明显增大,这表明CuO有烧结助熔作用,能降低烧成温度.     

稀土掺杂Pb(Mg1/3Nb2/3)O3-PbTiO3压电陶瓷的烧结特性研究

在传统的固相反应制备工艺中,固相反应的烧结温度直接影响着陶瓷的物相结构、陶瓷致密度以及介电性能等.本文采用固相反应法制备x; Sm3掺杂PMN-PT压电陶瓷,通过控制不同的烧结温度,制备了一系列Sm-PMNPT陶瓷样品.利用X射线衍射仪、介电温谱以及准静态d33测量仪对陶瓷结构、介电性能、压电系数等性能进行表征.研究结果表明:烧结温度在1250℃,x=1.875mol;～2.5mol;,陶瓷样品的钙钛矿含量最大,压电系数最高可达1254 pC/N,kp=0.58,相对介电常数高达30000左右,密度达到8.48 g/cm3.     

ZnO掺杂KNN陶瓷烧结行为与性能研究

采用固相烧结工艺制备了钙钛矿结构的(K0.5Na0.5)NbO3+ xwt;ZnO(x=0,0.5,1.0,2.0)无铅压电陶瓷.研究了ZnO掺杂对(K0.5Na0.5)NbO3陶瓷体系烧结行为和电学性能的影响.结果表明:ZnO掺杂能够有效地降低陶瓷烧结温度,抑制K和Na的挥发,提高陶瓷的致密性.当掺杂量为0.5 wt;、烧结温度为1115℃时,陶瓷的体积密度最大p=4.41 g/em3.所有样品的晶粒形态均为层状堆垛结构,晶粒尺寸越大,层状堆垛形态越明显.晶粒形态和尺寸的变化与(K0.5Na0.5)NbO3陶瓷烧结过程中液相的形成和晶粒生长机制有关.适量的液相能够有效地提高陶瓷的致密性,获得均匀的微结构.当x=0.5、烧结温度为1115℃时,陶瓷具有最佳的电学性能:d33=118pC/N,kp=0.36,Pr=15.6 μC/cm2.     

Pb0.92Sr0.08-xBax(Sb2/3Mn1/3)0.05Zr0.48Ti0.47O3的制备与性能研究

采用传统固相烧结法制备了Pb0.92Sr0.08-xBax(Sb2/3 Mn1/3)005Zr0.48Ti0.47O3(PSBSM-PZT)压电陶瓷样品.研究了不同Sr2+、Ba2+掺杂含量对样品的相结构、微观形貌、压电和介电性能的影响.结果显示:所有样品均为钙钛矿结构.而当x=0.02～0.06时,陶瓷样品组分位于准同型相界区(MPB).由于位于准同型相界区域的陶瓷样品对于电畴的转向具有促进作用,所以处于MPB区域的陶瓷样品具有较大的压电和介电性能,但同时由于电畴转向带来的较大内摩擦和结构损耗,从而提高了材料的机械损耗和介电损耗.当x=0.02时的陶瓷样品获得最佳的综合性能:d33=346 pC/N,kp=0.58,Qm=1217,εr=1724,tanδ=0.774;.     

Nb2O5掺杂对Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3陶瓷组织与性能的影响

采用固相烧结法制备Nb2O5掺杂的Pb(Mg1/3Nb2/3) O3-PbZrO3-PbTiO3+ 0.5mol; ZnO(PMN-PZT)压电陶瓷,研究了不同Nb2O5掺杂量对材料结构及压电介电性能的影响.实验结果表明,随着Nb2O5掺杂量的增加(0～1 mol;),PMN-PZT陶瓷的晶界强度提高,断裂模式由沿晶断裂逐渐转变为穿晶断裂,而且陶瓷的压电介电性能升高.当Nb2O5掺杂量为1mol;时,1250℃烧结的陶瓷样品性能参数为:d33=430 pC/N,Qm=60,kp=0.52,kt=0.38,εr=3620,tanδ=0.017.     

CaTiO3掺杂PbNb2O6高居里温度压电陶瓷的研究

采用传统电子陶瓷的制备方法,系统研究了(1-x)PbNb2O6-xCaTiO3(x=0、0.01、0.02、0.03、0.04)系高居里温度压电陶瓷.XRD分析表明,x=0时,材料只能形成三方非铁电相钨青铜结构,而x在0.01～0.04 mol范围内均能形成钨青铜型固溶体,利用XRD数据计算了晶体的晶格常数随x的变化,发现随着CaTiO3含量增加,晶胞体积减小.陶瓷材料的居里温度测试结果表明该体系具有高的居里温度(Tc＞400℃).测试了不同组成陶瓷的压电、介电性能,CaTiO3的掺杂量为x=0.03时陶瓷样品的压电常数达到d33=64pC/N,平面机电耦合系数kp=0.269,材料的介电常数ε33T/ε0=293,介质损耗tanδ=0.021,居里温度Tc=570℃,该组成具有优异的压电性能,适合于高温环境下的使用.     

非致冷In0.53Ga0.47 As/InP红外探测器研究

采用LPMOCVD技术生长了InGaAs红外探测器器件结构材料,其晶格失配为2.19×10-4.利用锌扩散制备探测器单元器件,光谱响应范围为0.90～1.70μm,在1.95V偏压下,暗电流为5.75×10-5A,在反向偏压为-5V时,电容为6.96×10-12F.探测器波段探测率为2.08×1011cmHz1/2W-1.     

弛豫铁电0.24PIN-0.47PMN-0.29PT单晶声表面波性能研究

随着信息技术的迅速发展,对声表面波器件的要求也进一步提高。为寻找性能更加优异的声表面波器件基底材料,本文利用分波解法对室温下[001]_c及[011]_c极化弛豫铁电0.24PIN-0.47PMN-0.29PT单晶的声表面波性能进行研究。利用[001]_c及[011]_c极化弛豫铁电0.24PIN-0.47PMN-0.29PT单晶的弹性、压电及介电性能参数,通过求解克里斯托弗方程计算了晶体声表面波相速度、机电耦合系数及能流角随传播角度的变换关系。结果表明,沿[011]_c方向极化的0.24PIN-0.47PMN-0.29PT单晶声表面波性能要优于沿[001]_c极化的单晶。[011]_c极化0.24PIN-0.47PMN-0.29PT单晶的声表面波机电耦合系数显著高于沿[001]_c极化单晶。同时沿[011]_c极化0.24PIN-0.47PMN-0.29PT单晶的声表面波能流角的最大值也明显小于[001]_c极化单晶。因此,沿[011]_c方向极化的0.24PIN-0.47PMN-0.29PT单晶兼具优异的声表面波性能及温度稳定性,更适合于实际应用。     

Quantum transport measurements on Si δ- and slab-doped In0.53Ga0.47As grown by molecular beam epitaxy

A series of high quality δ-doped In_0.53Ga_0.47As samples have been grown lattice matched to InP with design doping densities in the range 2×10¹² to 5×10¹² cm⁻². Analysis of the individual sub-band densities deduced from the Shubnikov-De Haas effect shows that both spreading and amphoteric behaviour increase with doping density.     

Gettering properties of PrO2 in In0.53Ga0.47As LPE growth

Praseodymium oxide was used for the gettering of background impurities from the melt, during In_0.53Ga_0.47As/InP LPE growth. The low amount of PrO₂ in the growth solution enables one to prepare n-type In_0.53Ga_0.47As epitaxial layers with electron concentration in the range of 2 × 10¹⁴ to 2 × 10¹⁶ cm^-3 and electron mobilities of 11,000 and 8400 cm²/V·s, respectively. These results were achieved without long time baking of the melt; homogenization lasted only 1 h. The electrical parameters and photoluminescence spectra of the grown layers are presented.     

Control of growth temperature at the onset of In0.53Ga0.47As growth by chemical beam epitaxy

Compositional grading has been observed during the initial 0.25 μm of InGaAs growth on In-free mounted, radiatively heated InP wafers. This has been related to a temperature rise occuring during the growth. X-ray diffraction measurements and rocking curve simulations have quantified the compositional variations as a function of depth, enabling a temperature profile to be derived from the known variation of composition with growth temperature. Use of a temperature ramp to compensate for the modelled temperature changes has led to the growth of near-perfect InGaAs layers with negligible compositional grading.     

Low dark current In0.53Ga0.47As/InP SAM avalanche photodiodes grown by gas-source MBE

In_0.53Ga_0.47As/InP avalanche photodiodes (APDs) with separate absorption and multiplication (SAM) regions have been grown by gas-source molecular beam epitaxy (GSMBE). These mesa-structure diodes, with a mesa diameter of 150 μm, exhibit a very low dark current of 17 nA, and primary unmultiplied dark current of less than 1.0 nA at 90% of the breakdown voltage. A gain as high as 100 is observed near the breakdown. Good uniformities of punch-through voltage and breakdown voltage were obtained on a 16 mm×16 mm wafer. Also, a premature breakdown was observed in the In_0.53Ga_0.47As/InP SAM-APDs with a V-shaped defect density of 25,000 cm^-2.     

The role of hydrogen in low-temperature MOVPE growth and carbon doping of In0.53Ga0.47As for InP-based HBT

Hydrogen radicals are decisive for the low-temperature growth and carbon doping of In_0.53Ga_0.47As in LP-MOVPE. This is demonstrated for the growth of highly p-type doped In_0.53Ga_0.47As layers with CCl₄ as dopant source. Perturbed angular correlation measurements (PAC) were used to investigate the passivation of acceptors by hydrogen in low-temperature grown In_0.53Ga_0.47As. Based on the above analysis an InP-based layer stack is developed which employs low-temperature growth of the base layer, high-temperature growth of the remaining HBT layers, and an in situ post-growth annealing under TMAs/N₂ ambient.     

X-ray Diffraction Analysis of the Structure In0.53Ga0.47As Films Grown on (100) and (111)A GaAs Substrates with a Metamorphic Buffer

Crystallography Reports - Epitaxial In0.53Ga0.47As films, grown on GaAs substrates with the (100) and (111)А crystallographic orientations in the standard high-temperature and low-temperature...     

Properties of (Ga0.47In0.53)As epitaxial layers grown by metalorganic vapor phase epitaxy (MOVPE) using alternative arsenic precursors

In this study, the use of novel, liquid, organic arsenic precursors as substitutes for the highly toxic hydride gas arsine (AsH₃) in low pressure metalorganic vapor phase epitaxy (LP-MOVPE) of (GaIn)As lattice matched on InP has been investigated. The model precursors out of the classes of (alkyl)3-nAsH_n (n = 0,1,2) are tertiarybutyl arsine (TBAs), ditertiarybutyl arsine (DitBAsH) and diethyltertiarybutyl arsine (DEtBAs). The MOVPE growth has been investigated in the temperature range of 570–650°C using V/III ratios from 2 to 20. The obtained epitaxial layer quality as examined by means of optical and scanning electron microscopy (SEM), high resolution double crystal X-ray diffraction, temperature-dependent van der Pauw-Hall, as well as photoluminescence (PL) measurements, will be compared for the different source molecules. Under optimized conditions almost uncompensated n-type (GaIn)As layers with carrier concentrations below 1 × 10¹⁵ cm⁻³ and corresponding mobilities above 80 000 cm²/V · s have been realized. For TBAs and DitBAsH in combination with the corresponding P sources TBP and DitBuPH, respectively, we have worked out a process parameter area for the growth of layers with device quality, as proven by the realization of a pin-detector structure.