Effect of milling time and pH on the dispersibility of lead zirconate titanate in aqueous media for inkjet printing

Micrometre-sized Pb(Zr_0.53Ti_0.47)O₃ (PZT) powder was dispersed in water, stabilized with the ammonium polyacrylate (PAANH₄) and milled to reduce the particle size. The influence of the pH, the amount of PAANH₄, and the milling time on the zeta potential, the PZT particle size and the particle size distribution was studied. The agglomeration took place regardless the milling time at pH 3. The suspension, containing 5 vol.% of PZT and 5 wt.% of PAANH₄, milled at pH 10 for 240 min, was stable and contained particles with a narrow, log-normal particle size distribution with the median size of 160 nm. The dissociated carboxyl groups from the PAANH₄ interacted with the PZT particles as evidenced by Fourier transform infrared spectroscopy and electrosterically stabilized the particles in water at pH 10. The PZT particle size and the stability of the suspension fitted the requirements for the ink, suitable for ink-jet printing.     

Analysis of composition homogeneity and polarization orientation of PZT submicron fibers by micro-Raman spectroscopy

Micro-Raman spectroscopy is a convenient tool to probe individual objects with a feature size on the submicron scale. The phase, composition, and orientation of Pb(Zr,Ti)O₃ fibers fabricated via hydrothermal processing have been characterized by this technique, with the working principles given in the paper. It is shown that the prepared PZT submicron fibers are of a tetragonal pervoskite phase, with Zr/(Zr + Ti) varying from 0.05 to 0.25. The spontaneous polarization has been confirmed to be along the length direction and one of its {1 0 0} planes parallel to the substrate plane.     

制备工艺对0.95(K_(0.5)Na_(0.5))NbO_3-0.05CaZrO_3基无铅陶瓷压电性能的影响

采用传统陶瓷工艺制备了0.95(K0.5Na0.5)NbO3-0.05CaZrO3无铅压电陶瓷。研究了烧结温度和极化工艺对陶瓷压电性能的影响。结果表明:随着烧结温度的提高,0.95(K0.5Na0.5)NbO3-0.05CaZrO3陶瓷的体积密度增大,在1170℃时达到最大值,同时d33和kp,在此温度也分别达到他们的最大值210pC/N和0.40。极化工艺对0.95(K0.5Na0.5)NbO3-0.05CaZrO3陶瓷的压电性能有明显的影响,0.95(K0.5Na0.5)NbO3-0.05CaZrO3陶瓷的最佳极化温度是70℃,最佳极化电场是4kV/mm。     

汽油中铁、铅含量的测定

针对原有测量标准进行微调,选用商品标准溶液稀释、配制成一系列的工作溶液。选择合适的测量条件,用火焰吸收法测定了汽油中铁、铅离子的含量。针对新方法的检出限、准确度、回收率等进行了讨论,确定了新方法的可行性以及测量的最佳条件、测量特性。     

Static structure and dynamic properties in liquid Sn96.2 Ag3.8 lead free solder: Structure factor,diffusion coefficients and viscosity

Starting from the pseudopotential formalism, we developed a new pseudopotential able to describe accurately both heavy metals like tin and noble metals like copper and silver which are the basic elements of the new lead free solders. The pseudopotential describes the interaction between electrons and ions. To describe the atomic structure it is necessary to use an effective pair potential describing the interaction between ions taking into account the electron screening cloud. This pair potential is deduced from our new pseudopotential. It enters into a simulation program using molecular dynamics. First we calculate the atomic structure factor that has been compared to that measured experimentally by neutron or X ray scattering. In the case of a binary alloy, we determined three partial structure factors describing the system. These can be calculated but in general cannot be obtained experimentally. To do a comparison we must combine adequately the calculated partial structure factors and compare it to the experimental total structure factor. By molecular dynamics we can follow the individual movement of particles to obtain the different diffusion coefficients which, as partial structure factors, are very difficult to measure accurately. We followed the collective movement of all particles and got the shear viscosity by Green–Kubo formalism. We compared our results to the existing experimental viscosity which is a little easier to measure. However, in the bibliography, we observe high discrepancies between the different authors. It is thus important to be able to calculate accurately these properties as functions of temperature and composition.     

Domain switching characteristics of lead zirconate titanate piezoelectric ceramics on a nanoscopic scale

Domain switching characteristics of lead zirconate titanate ceramics with and without poling under compressive loading are investigated using electron backscatter diffraction. For loading in the poling direction, the switching strain is stronger than that for loading perpendicular to the poling direction. There is strong domain switching when the domain (c-axis of the tetragonal structure) is orientated close to the loading direction. A large number of domains are switched between 85.4° and 90.0°, with many crossing the loading axis. Each grain consists of domains with three different patterns; i.e., with c-axis orientated in three directions in each grain. The patterns remain unchanged even with domain switching and strong deformation. However, the ratios among the patterns depend on compressive stress. Under stress, one or two specific domain modes are switched to about 90°, although others are not switched as much. These domain switching characteristics are related to the poling and loading directions. 90° domain switching model is proposed on the basis of twin deformation model. Due to the aspect ratio of c/a = 1.014 (tetragonal structure), the angle of the switching is less than 90° (89.2°). This angle is corresponding to the switching angle obtained by an electron backscatter diffraction analysis (Ave. 88.9°).     

Stability studies of PbS sensitised TiO2 nanotube arrays for visible light photocatalytic applications by X-ray photoelectron spectroscopy (XPS)

Titania nanotube array sensitised with lead sulphide (PbS) were synthesised using a successive ionic layer adsorption and reaction (SILAR) method. The PbS sensitation gives visible light sensitivity to the titania nanotube arrays. The PbS sensitised titania nanotube were characterised using X-ray diffraction, UV–visible spectroscopy and scanning electron microscopy. The stability of the PbS sensitised titania nanotube were monitored through the X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the titania sensitised with PbS were studied by monitoring the degradation of methylene blue under visible light irradiation. The photocatalytic activity and solar cell efficiency is found to be highly depended on the number of SILAR cycle used for the sensitisation of PbS on titania nanotube. The sample coated for 3 SILAR cycle of PbS shows highest solar cell efficiency and photocatalytic activity under visible light. The photocatalytic activity drastically decreased in the samples after the Ist cycle of photocatalytic reaction. The drastic decrease in the photoactivity is due to the dissolution of PbS nanoparticle on the surface of titania nanotube after the first cycle of photocatalytic reaction. XPS was employed as a tool to probe the dissolution of PbS nanoparticles.     

Gadolinia-modified ceria photocatalyst for removal of lead (II) ions from aqueous solutions

Gd₂O₃-modified CeO₂ particles are prepared by a solid-state reaction method, and are used to remove Pb(II) ions from aqueous solutions by a photoelectrodeposition. The UV–photocatalytic activity for Pb(II) ion removal of the Gd₂O₃-modified CeO₂ is significantly higher than that of pure CeO₂. A solid solution Gd_0.1Ce_0.9O_1.95 phase coexisting with the CeO₂ matrix phase shows a high ability of photoelectrodeposition for the Pb(II) ions removal, compared to the two-phases mixture of Gd₂O₃–CeO₂. The high photocatalytic activity is also supported by a strong photoluminescence (PL) signal from the Gd_0.1Ce_0.9O_1.95–CeO₂. The high activity can be due to a formation of heterojunctions between p-type Gd_0.1Ce_0.9O_1.95 and n-type CeO₂, promoting transfer of photogenerated electron–hole pairs and efficiency restraining recombination of the charges.     

Resistance reduction effect of potassium bismuth titanate doping in yttrium–manganese co-doped medium Curie temperature barium titanate lead free ceramics through improved synthesis process

Through improved synthesis process, resistance reduction effect of (K_0.5Bi_0.5)TiO₃ (KBT) doping in Y–Mn co-doped BaTiO₃ (BT) lead free ceramics was investigated. By different doping methods (doping K₂O, Bi₂O₃ and TiO₂ or synthesized KBT), medium Curie temperature (around 130 °C) lead free BT ceramics were obtained with ultra-low resistivity (13.84 Ωcm) with a temperature maintaining process at 700 °C. In this contribution, effect of sintering process and doping methods is discussed in detail.     

Effect of annealing temperature on optical and electrical properties of lead sulfide thin films

Lead sulfide (PbS) thin films with 150 nm thickness were prepared onto ultra-clean quartz substrate by the RF-sputtering deposition method. Deposited thin films of PbS were annealed at different temperatures 100 °C, 150 °C, 200 °C, 250 °C and 300 °C. X-ray diffraction pattern of thin films revealed that thin films crystallized at 150 °C. Crystalline thin films had cubic phase and rock salt structure. The average crystallite size of crystalline thin films was 22 nm, 28 nm and 29 nm for 150 °C, 200 °C and 250 °C respectively. From 150 °C to 250 °C increase in annealing temperature leads to increase in crystallite arrangement. FESEM images of thin films revealed that crystallite arrangement improved by increasing annealing temperature up to 250 °C. Increase in DC electrical conductivity by increasing temperature confirmed the semiconductor nature of crystalline thin films. Increase in dark current by increasing annealing temperature showed the effect of crystallite arrangement on carrier transport. Photosensitivity decreased by increasing annealing temperature for crystalline thin films that it was explained at the base of thermal quenching of photoconductivity and adsorption of oxygen at the surface of thin films that leads to the formation of PbO at higher temperatures.