[en] Pt/PbZr_0.53Ti_0.47O₃ (PZT)/LaAlO₃ (LAO)/Si and Pt/PbZr_0.53Ti_0.47O₃/La_0.85Sr_0.15CoO₃ (LSCO)/LaAlO₃/Si structures for ferroelectric field effect memory applications were fabricated on n-type Si substrate by pulsed laser deposition (PLD). The Auger electron spectrometry (AES) analysis shows that a LaAlO₃ buffer layer can effectively prevent Si and Ti, Pb interdiffusion between PZT and Si substrate. For both of the structure, the current density-voltage measurement shows a typical leakage current density of about 10^-7 A/cm² at 8 V applied voltage. Furthermore, it has been demonstrated that the PbZr_0.53Ti_0.47O₃/LaAlO₃/Si structures and Pt/PbZr_0.53Ti_0.47O₃/La_0.85Sr_0.15CoO₃/LaAlO₃/Si structures exhibit ferroelectric switching properties, showing a memory window as large as 2 and 2.9 V, respectively, under a ramp rate of 200 mV/s from -6 to +6 V driving voltage at 1 MHz. It is believed that the La_0.85Sr_0.15CoO₃ buffer layer deposited on LaAlO₃ layer can improve the crystalline properties of PZT films, and then result in lager polarization of PZT and lager memory windows for Pt/PbZr_0.53Ti_0.47O₃/La_0.85Sr_0.15CoO₃/LaAlO₃/Si structures

[en] The Pobei mafic-ultramafic complex in northwestern China comprises magmatic Cu-Ni sulfide ore deposits coexisting with Fe-Ti oxide deposits. The Poshi, Poyi, and Podong ultramafic intrusions host the Cu-Ni ore. The ultramafic intrusions experienced four stages during its formation. The intrusion sequence was as follows: dunite, hornblende-peridotite, wehrlite and pyroxenite. The wall rock of the ultramafic intrusions is the gabbro intrusion in the southwestern of the Pobei complex. The Xiaochangshan magmatic deposit outcrops in the magnetitemineralized gabbro in the northeastern part of the Pobei complex. The main emplacement events related to the mineralization in the Pobei complex, are the magnetite-mineralized gabbro related to the Xiaochangshan Fe deposit, the gabbro intrusion associated to the Poyi, Poshi and Podong Cu-Ni deposits, and the ultramafic intrusions that host Cu-Ni deposits (Poyi and Poshi). The U-Pb age of the magnetite-mineralized gabbro is 276±1.7Ma, which is similar to that of the Pobei mafic intrusions. The εHf(t) value of zircon in the magnetite-mineralized gabbro is almost the same as that of the gabbro around the Poyi and Poshi Cu-Ni deposits, indicating that the rocks related to Cu-Ni and magnetite deposits probably originated from the same parental magma. There is a trend of crystallization differentiation evolution in the Harker diagram from the dunite in the Cu-Ni deposit to the magnetite-mineralized gabbro. The monosulfide solid solution fractional crystallization was weak in Pobei; thus, the Pd/Ir values were only influenced by the crystallization of silicate minerals. The more complete the magma evolution is, the greater is the Pd/Ir ratio. The Pd/Ir values of dunite, the lithofacies containing sulfide (including hornblende peridotite, wehrlite, and pyroxenite) in the Poyi Cu-Ni deposit, magnetite-mineralized gabbro, and massive magnetite, are 8.55, 12.18, 12.26, and 18.14, respectively. Thus, the massive magnetite was probably the latest product in the evolution of the Pobei mafic-ultramafic intrusions. We infer that the Cu-Ni sulfide and Fe-Ti oxide ores in the Pobei area were products of a cogenetic magma at different evolutionary stages; at the late stage, the magma became iron enriched through crystallization differentiation. The magma differentiation occurred in a deep staging magma chamber emplaced in the upper magma chamber. Earlier crystallized olivine with some interstitial sulfides gathered at the bottom of the staging magma chamber because of its greater density. That is to say, the ultramafic magma hosting the Cu-Ni sulfide formed at the bottom of the staging magma chamber, while the magnetite-mineralized gabbro was in the upper part. However, the magnetite-mineralized gabbro injected into the upper magma chamber first and the ultramafic lithofacies containing the olivine and the interstitial Cu-Ni sulfides were subsequently emplaced in the upper magma chamber as crystal mush.

[en] Herein, we report four self-assembly Iron(II/III) complex consisting triethanolamine (TEOA) as ligand and an FeIII(TPA)Cl3 (TPA= 3-(2-pyridine methyl) amine) as contrast catalyst, for photochemical reduction of CO/sub 2/ to CO under visible light. The photocatalytic systems were assembled by [Ru(bpy)3]Cl2 as photosensitizer, and 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo-[d]-imidazole (BIH) as electron donor. Experiments are conducted to study the relationship between CO production and the external ions. Different external counterions are provided to assist the discussion of the influence of these external ions on catalysis. Density functional theory calculations confirmed that the external ions have an effect on the CO yield. Moreover, a mechanism involving proton-coupled electron transfer is proposed. (author)

[en] SrZrO₃ (SZO) thin films have been prepared on Pt-coated silicon substrates and directly on Si substrates by pulsed laser deposition (PLD) using a ZrSrO target at a substrate temperature of 400 °C in 20 Pa oxygen ambient. X-ray θ–2θ scans showed that the as-deposited films remain amorphous at a substrate temperature of 400 °C. The dielectric constant of SZO has been determined to be in the range 24–27 for the Pt/SZO/Pt structure. Capacitance–voltage (C–V) characteristics of a metal-oxide-semiconductor (MOS) structure for SZO films deposited in 20 Pa oxygen ambient and 20 Pa nitrogen ambient (SZON) indicated that incorporation of nitrogen during the substrate heating and film deposition can suppress the formation of an interfacial SiO₂ layer, and the SZON films have a lower equivalent oxide thickness (EOT) than that of the SZO films. However, the leakage current of the SZON films is larger than that of the SZO films. The EOT is about 1.2 nm for a 5-nm SZON film deposited at 400 °C. The leakage-current characteristics of as-deposited SZON films and SZON films post-annealed in oxygen ambient by rapid thermal annealing (RTA) have been studied comparatively. The films post-annealed with RTA have a lower leakage current than the as-deposited SZON films. Optical transmittance measurements showed that the band gap of the films is about 5.7 eV. It is proposed that SrZrO₃ films prepared at 400 °C are potential materials for alternative high-k gate-dielectric applications.

[en] On the basis of using SHS gravitational separation process to fabricate ceramic-lined composite pipes, lined multiphase ceramics with hypoeutectic composition and laminar or fiber (Al₂O₃+Z_rO₂) eutecticum base were obtained by means of in-situ crystallization, and fracture toughness of the ceramics was up to 15.96 MPa.m^0.5 after Vickers IM testing. It was demonstrated from SEM observation and analyses on fracture mechanic of ceramics that crack extension was strongly influenced by bridging of fiber eutecticum, bridging of laminar eutecticum, which resulted in existence of strong shielding effect around advanced crack tip and strong toughening mechanism due to crack deflection, so that high fracture toughness of the ceramics was maintained. (orig.)

[en] This paper investigates the interfacial characteristics of LaAlO₃ (LAO) and LaAlO_xN_y (LAON) films deposited directly on silicon substrates by the pulsed-laser deposition technique. High-resolution transmission electron microscopy (HRTEM) pictures indicate that an interfacial reaction between LAO and Si often exists. The interfacial layer thickness of LAO films deposited in a nitrogen ambient atmosphere is smaller than that of LAO films deposited in an oxygen ambient atmosphere. X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were used to study the composition of the interfacial layer. The shift of the La 3d photoelectron peak to a higher binding energy compared to LaAlO₃, the shift of the Al 2p peak to a higher binding energy compared to LaAlO₃, the shift of the Si 2p peak to a lower binding energy compared to SiO₂ and the intermediate location of the O 1s peak compared to LaAlO₃ and SiO₂ indicate the existence of a La-Al-Si-O bonding structure, which was also proved by the AES depth profile of LAO films. It can be concluded that the interfacial layer is not simply SiO₂ but a compound of La-Al-Si-O. (orig.)

[en] High-k gate dielectric material LaAlO₃ (LAO) films were deposited directly onto silicon substrates by laser molecular-beam epitaxy. The thermodynamic stability of LAO films deposited at different substrate temperatures and of LAO films postannealed at 1000 deg. C was studied by high-resolution transmission electron microscopy and capacitor-voltage measurements. These studies show that the interfacial reaction between the LAO film and silicon substrate is strongly correlated to the substrate temperature and ambient conditions. In oxygen containing ambient, the interfacial reaction often occurs not only during film deposition but also during the course of postannealing. LAO films annealed at 1000 deg. C in nitrogen ambient have better thermal stability with silicon than LAO films annealed in oxygen ambient do. Both kinds of films remain amorphous after 1000 deg. C annealing

[en] Forming gas (FG) annealing effects of a nonvolatile flash memory structure using Ge nanocrystals (NCs) floating gate embedded in LaAlO₃ high-k tunneling/control oxide were studied. Atomic force microscopy and high-resolution transmission electron microscopy measurements revealed that the pulsed-laser deposited Ge NCs were well self-organized and the average diameter of the sphere-like NCs was around 6 nm. By using a double sweep capacitance-voltage measurement, memory windows of 1.4 and 1.0 V were obtained for the as-deposited and FG annealed samples, respectively. The charge loss rate of the FG annealed sample was lower than that of the as-deposited sample, and this could be explained by the decrease of defects in the dielectrics and Ge NCs as well as their interfacial states that may have acted as charge leak channels

[en] High permittivity LaAlO₃ (LAO) and LaAlO_xN_y (LAON) thin films have been deposited directly on a Si(100) substrate using a laser molecular-beam epitaxy technique. Metal-oxide-silicon field-effect transistors (MOSFETs) are fabricated using such LAO and LAON thin films as gate dielectrics and well-behaved transistor characteristics have been observed. High-resolution transmission electron microscopy observations indicate that LAO thin films can remain amorphous structure even after annealing at 1000 deg. C. The small equivalent oxide thickness (EOT) of 17 A is achieved for 75 A LAO film with an effective dielectric constant of 17.2±1 for the whole gate stack. Furthermore, a smaller EOT, larger drive current, and lower subthreshold slope have been observed for devices with the LAON thin film. For all the devices, the gate leakage currents are at least two orders of magnitude lower than that of the same electrical thickness SiO₂. Reasonable subthreshold slopes of 248 and 181 mV/dec were obtained for MOSFETs with LAO and LAON films, respectively

[en] Highlights: • Single phase Sc doped BFO ceramics were successfully fabricated. • Dielectric constant and magnetization are enhanced in doped BFO system. • Polarization first increases and then decreases in doped BFO system. • M_r of 0.0105 emu/g and P_r of 16.1 μC/cm"2 were revealed simultaneously at x = 0.01. - Abstract: Multiferroic BiFe_1_−_xSc_xO_3 ceramics with x = 0.00–0.10 were synthesized by rapid liquid phase sintering. The influences of Sc doping on the crystalline structures, dielectric, ferroelectric, and magnetic behaviors of BiFeO_3 ceramics were explored. The X-ray diffraction and the Raman spectrometric analysis revealed that all the samples are nearly single phase of rhombohedral structure with the incorporation of Sc ions into BiFeO_3. With increase doping concentration of x, the dielectric constant, dielectric loss, and remnant polarization for the doped BiFeO_3 increase first and then drop down with further rise of x. A saturated ferroelectric polarization can be achieved at a small amount of Sc doping concentration (x < 0.03), with a optimized remnant polarization of 17.6 μC/cm"2 at x = 0.03. Meanwhile, the magnetization is also slightly increased by introducing Sc dopant, with a maximum remnant magnetization of 0.0105 emu/g at x = 0.01. These results indicate that BiFeO_3 ceramics with small amounts of Sc-doping may be promising for applications in magnetoelectric devices