Fe3+/Bi3+对纯相BiFeO3薄膜的影响及生长机理研究

以Bi(NO3)3·5H2O,Fe(NO3)3·9H2O为原料,柠檬酸为螯合剂,用液相自组装法,在ITO玻璃基片上制备了纯相BiFeO3薄膜.研究了前驱液中Fe3+/Bi3+摩尔比对BiFeO3薄膜的影响.利用XRD,EDS,XPS,FE-SEM和FT-IR等测试手段对BiFeO3薄膜进行了表征.结果表明,由于柠檬酸对...     

退火工艺对液相自组装法制备BiFeO3薄膜的影响

以Bi(NO3)3·5H2O,Fe(NO3)3·9H2O和柠檬酸为主要原料,采用液相自组装法,以OTS单分子层为模板,在ITO玻璃基片上成功制备了BiFeO3晶态薄膜.研究了退火温度以及保温时间对BiFeO3薄膜的影响.利用DSC/TG对铁酸铋前驱物结晶行为进行了表征,利用XRD和FE-SEM等测试手段对不同退火工艺下...     

溶胶-凝胶法制备0.1BiFeO3-0.9SrBi2Nb2O9铁电薄膜的结构和光学性质研究

采用硝酸铋[Bi(NO3)3·5H2O]、硝酸锶[Sr(NO3)2]、硝酸铁[Fe(NO3)3·9H2O]和乙醇铌[Nb(OC2H5)5]作为起始原料,乙二醇甲醚[C3H8O2]作为溶剂配制掺Fe的SrBi2Nb2O9前驱体溶液,利用溶胶-凝胶法在石英衬底上制备出0.1BiFeO3-0.9SrBi2Nb2O9铁电薄膜.研究了该薄膜的表面形貌、组分、晶体结构和光学性质.结果表明,经400℃退火后薄膜为非晶结构,而在空气中经600℃退火1h后,沉积的薄膜晶化成钙钛矿结构.制备的薄膜表面平整,颗粒分布均匀,表现出良好的光透过性,该薄膜的光学能隙大约为2.5eV.     

BiFeO_3的水热合成、表征及光催化性能研究

以Bi(NO3)3.5H2O和Fe(NO3)3.9H2O为原料,KOH为矿化剂,聚乙二醇6000为分散剂,水热合成了单相BiFeO3粉体,利用X射线衍射、扫描电镜优化了水热合成条件,利用振动样品磁强计测定了BiFeO3的磁滞回线,并对产物进行了光催化降解甲基橙性能的研究。结果表明,200℃条件下反应6h制备的BiFeO3粉体显顺磁性,紫外光照射4h对甲基橙的降解率可达90%。     

水热可控合成多面体BiFeO3颗粒

以Bi(NO)3·5H2O和Fe(NO)3·9H2O为水热反应原料,选择KOH作为矿化剂合成单相BiFeO3.通过调节KOH浓度和升降温速率可控合成了规则的大尺度多面体BiFeO3颗粒.发现高碱浓度有利于合成规则多面体BiFeO3颗粒,合适的水热降温速率是影响高结晶度BiFeO3颗粒合成的重要因素之一.当KOH浓度为6和8 mol/L,降温速率为0.2℃/min时,产物为高结晶度准立方和截角立方颗粒,当降温速率调节为0.1℃/min时,产物为表面粗糙的立方八面体和截角八面体颗粒.当KOH浓度为8 mol/L,降温速率约为2℃/min时,产物为表面粗糙且有孔洞的截角立方颗粒.通过扫描电镜图片观察到其形貌演变过程并解释了大尺度多面体BiFeO3颗粒的形成机制.     

pH值和无机盐添加剂对水热合成钨酸铋的影响

在170℃的温和水热条件下,用Na2WO4·2H2O、Bi(NO3)3·5H2O为原料,硝酸钠为添加剂辅助制备了三维(3D)花球状钨酸铋粉体。通过改变添加剂的浓度,发现硝酸钠在诱导花球状钨酸铋的生长和自组装过程中起到关键作用。在合适添加剂浓度的基础上,pH值的变化会对产物的物相和微观形貌有很大的影响。研究结果表明,当pH值≤10.8时,产物为Bi2WO6,当pH值=12.4时,产物转变为Bi3.84W0.16O6.24。当pH值=1.2,硝酸钠浓度为4 mol/L时,获得粉体的比表面积为33.427m2/g。     

Bi_2WO_6催化剂的合成及光催化性能的研究

以Bi(NO3)3·5H2O和Na2WO4·2H2O为原料,采用水热法制备Bi2WO6催化剂,在λ420nm的可见光区降解模拟罗丹明B(RhB)废水,研究前驱物pH值、水热反应温度和时间对Bi2WO6催化性能的影响;通过X射线衍射(XRD)、扫描电镜(SEM)、紫外-可见吸收光谱(UV-Vis)和比表面积(BET)表征,考察前驱物pH值对催化剂晶型、形貌、吸光性和比表面积的影响。结果表明,前驱物pH值为Bi2WO6光催化活性的关键影响因素,且对产物微观结构影响较大。当pH值=4.5时合成的产物光催化活性最佳,反应90 min RhB溶液降解率达到99.90%,经重复使用4次,其光催化效果无明显降低,表明该Bi2WO6是一种有效稳定的可见光催化剂。     

Sol-gel方法制备BiFeO_3/Bi_4Ti_3O_(12)多层薄膜及其电性能

采用溶胶-凝胶方法在FTO/glass底电极上制备了BiFeO3/Bi4Ti3O12和Bi4Ti3O12/BiFeO3多层薄膜。研究了室温下薄膜的结构,铁电性质和介电性质,并将其与纯的BiFeO3薄膜的性质进行了比较。从薄膜的XRD模式中可以观察到共存的BiFeO3相和Bi4Ti3O12相。通过电滞回线测量可以看出,相对于纯的BiFeO3薄膜,BiFeO3/Bi4Ti3O12和Bi4Ti3O12/BiFeO3多层薄膜能够承受更高的测试电场而获得充分极化,从而表现出较强的铁电性,在450kV/cm测试电场下,薄膜的剩余极化强度分别为37μC/cm2和23μC/cm2。     

硝酸铝溶解制备增塑壳聚糖薄膜的结构与性能

采用硝酸铝[Al(NO3)3·9H2O]水溶液为溶剂溶解壳聚糖,并加入甘油增塑改性制备壳聚糖薄膜,研究了Al(NO3)3·9H2O对壳聚糖的溶解效果和Al(NO3)3·9H2O/甘油协同增塑改性壳聚糖的效果。采用紫外可见光透光率,X射线衍射和力学性能测试研究了所得壳聚糖薄膜的光学性能,结晶性能和力学性能。研究结果表明,Al(NO3)3·9H2O水溶液可较好地溶解壳聚糖,但当Al(NO3)3·9H2O加量过高时,Al(NO3)3·9H2O水解生成的Al(OH)3会破坏壳聚糖的成膜性能。Al(NO3)3·9H2O适宜的质量分数为75%。当加入质量分数为75%的Al(NO3)3·9H2O改性时,壳聚糖薄膜的结晶度提高,透光率增加。力学性能测试结果表明,加入甘油改性后壳聚糖薄膜的拉伸强度降低,断裂伸长率提高。     

掺杂型SnO2薄膜对乙醇的气敏特性

以SnCl4·5H2O、Ce(NO3)3·6H2O、CuCl2·2H2O、La(NO3)3·6H2O为原料,柠檬酸为络合剂,采用sol-gel法,浸渍提拉技术制备了纯SnO2及其掺杂薄膜.利用XRD分析方法进行了物相结构分析,研究了掺杂比对各掺杂SnO2薄膜元件气敏特性的影响.发现掺杂比相同时,掺杂Ce3+的SnO2样...     

Path-independent phase unwrapping of subsampled phase maps

A technique for unwrapping subsampled phase maps is presented. The subsampled phase map is obtained by standard phase-shifting methods that use subsampled interferograms. The technique then estimates the wrapped local curvature of the subsampled phase map. This local curvature is then low-pass filtered with a free-boundary low-pass filter to reduce phase noise. Finally the estimated local curvature of the wave front is integrated by the use of a least-squares technique to obtain the searched continuous wave front.     

The phase representation of covariant phase observables

Abstract

Covariant phase observables are obtained by defining simple conditions for mappings from the set of phase wavefunctions (unit vectors of the Hardy space) to the set of phase probability densities. The existence of phase probability density for any phase wavefunction, the existence of interference effects and the natural phase shift covariance are those simple conditions. The non-localizability of covariant phase observables is proved.     

Full-field phase error compensation method based on relationship between unwrapped phase and phase error

The three-dimensional reconstruction in phase-measuring profilometry (PMP) usually involves the phase error caused by the gamma effect of the projector. In this study, the relationship between the unwrapped phase and the phase error of every pixel is analysed, and an effective full-field phase error compensation method based on this relationship is proposed for the reduction of every pixel error. In our optimized PMP system, the full-field phase error can be detected by directly fitting the unwrapped phase of the reference plane. In addition, the relationship between the unwrapped phase and the phase error can be established by creating a phase-error lookup table for the phase error compensation of every pixel. The experimental results demonstrate the effectiveness of the proposed method in practical PMP, and the measurement errors can be reduced by a factor of least 10.     

Complete phase transfer of hydrophobic magnetic nanocrystals into aqueous phase

The effective phase transfer of hydrophobic nanocrystals synthesized in nonpolar solvents into polar solvents remains great challenge for their nanomedicinal applications. To resolve this issue, the exsiting strategies for phase transfer of nanocrystals in organic solvents use amphiphilic compounds or lipids as imperative moieties by ligand exchange and encapsulations. Ligand exchange involves by exchanging the hydrophobic molecules with bifunctional compounds and small size of molecules is coordinated with functional molecules to increase the steric repulsion forces between boundary of water and nanoparticles. However, the yield of phase transferred nanocrystals from hydrophobic nonpolar to hydrophilic polar phase is exceptionally low, and sometime irreversible desorption of replaced ligands leads to agglomeration and aggregation. Also, their intrinsic physiochemical properties are easily influenced by surrounding ion species or pH when the particles are suspended in phosphate saline buffer (PBS). Moreover, conjugation of bioactive molecules often leads to colloidal instability in PBS because of the hydrodynamic nature of the amphiphilic molecules on the surfaces of nanoparticles. Here we report a robust and simple post-synthetic surface modification procedure of hydrophobic nanoparticles to remove the original surface-bound carboxylic acid and increase the water-solubility for nanomedicinal applications.     

采出液中固相颗粒对三相分离器性能的影响

为研究采出液中固相颗粒对气液固三相分离器性能的影响,基于计算流体力学软件Fluent,模拟分析三元驱采出液内所含的固相颗粒粒度及含量变化对三相分离旋流器处理固相体积分数分布、速度场和除砂分离效果的影响。结果表明:入口固相颗粒粒度变化对其径向速度影响较大,呈线性影响关系,颗粒粒径越大,流向旋流器器壁的径向速度越大,粒径不同对切向速度和轴向速度影响较小;固相含量增加,旋流器固相质量分离效率呈先增大后减小的趋势。     

Sensing wave-front amplitude and phase with phase diversity

We show in benchtop experiments that wave-front phase estimation by phase diversity can be significantly improved by simultaneous amplitude estimation. Processing speed, which will be important for real-time wave-front control applications, can be enhanced by use of small-format detectors with pixels that do not fully sample the diffraction limit. Using an object-independent phase-diversity algorithm, we show that, for both pointlike and extended objects, the fidelity of the phase and amplitude estimates degrades gracefully, rather than catastrophically, as the sampling becomes coarser. We show in simulation that the same algorithm also improves the fidelity of image reconstruction of complex targets.     

嵌入式相电检测及相序调整系统设计

针对许多行业有三相电相序与安全生产的要求,设计了基于32位ARM9处理器芯片S3C2410X的嵌入式系统,并移植了Linux操作系统来提高系统多任务与实时响应能力.介绍了该系统各硬件模块设计和软件设计流程,硬件模块由相电检测、相序调整、人机交互及TC35i报警等模块构成.该系统可对"三相四线制"供电端口进行相电检测与相序调整,在出现异常时执行报警操作并短信或者电话通知到负责人员,可应用于压缩机、风机和三相电机等装置的供电,特别适用于大型的移动供配电设备.     

A novel phase noise measurement of phase modulation microwave photonic links

Abstract

Microwave photonic links can provide many advantages over traditional coaxial due to its low loss, small size, lightweight, large bandwidth and immunity to external interference. In this paper, a novel phase noise measurement system is built, since the input signal and the power supply noise can be effectively cancelled by a two-arm configuration without the phase locking. Using this approach, the phase noise performance of the 10-GHz phase modulation photonic link has been measured for the first time, evaluated the values of ?124 dBc/Hz at 1 kHz offset and ?132 dBc/Hz at 10 kHz offset is obtained. Theoretical analysis on the phase noise measurement system calibration is also discussed.