Nanotechnology is at the stage where industry-wide implementation of this technology is approaching, safety is guaranteed, and social acceptance is a fact. Future questions that arise, while speculative, are whether people will live longer, safer, more sustainably, and healthily? Will the quantum computer make its appearance? Do we no longer communicate only via electrons but mainly via photons? Are the materials so intelligent that they fully adapt to the circumstances or provide us with full renewable energy? Will the food production be such that the expected shortages belong to the past? Is our safety guaranteed by a conditioned environment? Or to mention an important goal: is cancer history? These are questions to which there are no ready-made answers. It is clear that the advancement of technology, such as nanotechnology, will play an essential role. For a further development of nanotechnology, it is important to link scientific agendas with innovative challenges, to integrate a component of societal relevance, and to recognize the need for collaboration between science and industry, including the ethical aspects. This must include the entire secure chain, from science-spinoff- start-up-small and medium-sized enterprises-large companies-end user.

For thin film synthesis of complex oxides, one of the most important issues has always been how to oxidise the material. For a technique like pulsed laser deposition, a key benefit is the relatively high oxygen background pressure one can operate at, and therefor oxidation should be relatively straightforward. However, understanding the microscopic oxidation mechanisms turns out to be rather difficult. In this perspective, we give a brief overview of the sources of oxidation for complex oxide thin films grown by pulsed laser deposition. While it is clear what these sources are, their role in the kinetics of the formation of the crystal structure and oxygen stoichiometry is not fully understood.

Variation of the Ca/P ratio in hydroxyapatite (Ca10(PO4)6(OH)2) thin films was studied in relation to the spot size of the ablation laser for two different spatial energy distributions in pulsed laser deposition. One energy distribution is the defocus method with a raw distribution and the other is the projection method without the weak portion at the edges of the ablation laser spot. A Ca/P ratio closer to that of stoichiometry was obtained with the larger spot sizes for both methods, and with the projection method compared to the defocus method. It is considered that a more uniform spatial energy distribution of the ablation laser improves the Ca/P ratio.

Perovskite oxide heteroepitaxy is realized on the top of inorganic nanosheets that are covering the amorphous oxide surfaces of Si substrates. Utilizing pulsed laser deposition, thin films of SrRuO3 in a (001)pc and (110)pc orientation on nanosheets of Ca2Nb3O10 and Ti0.87O2 are grown, respectively. The two types of nanosheets are patterned to locally tailor the crystallographic orientation and properties of SrRuO3. The success of our approach is demonstrated by electron backscatter diffraction and spatial magnetization maps. An unprecedented control of perovskite film growth on arbitrary substrates is illustrated in this work, and the methods that are developed to deposit SrRuO3 thin films are a viable starting point for growth of artificial heteroepitaxial thin films that require a bottom electrode. Control is not just reached in the direction of film growth, as the crystal orientation and film properties are regulated laterally on the surface of micropatterned nanosheets. Local control of magnetic properties is illustrated, which holds out prospects for the fabrication of next‐generation devices like noncollinear magnetic random access memories.

The influence of the layer thickness of mixed ionic–electronic conducting (MIEC) cathodes and the type of noble metal current collector on the apparent surface exchange resistance is studied with impedance spectroscopy. The impedance data is analyzed with the ‘General Finite Length Diffusion’ transfer function. Also a simple relation is derived for the influence of the electronic sheet resistance of a thin layer on the apparent exchange resistance. These analysis methods are applied to a set of thin, dense layer electrodes of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) deposited on a Ce0.9Gd0.1O1.95 electrolyte by pulsed laser deposition (PLD). The apparent chemical capacitance is used to check the reliability of obtaining the oxygen exchange rate from the layer resistance. Use of a fresh, clean platinum gauze current collector significantly enhances the surface oxygen exchange rate on LSCF. But both ‘noble metal’ current collectors, Pt and Au, cannot be considered to be inert on LSCF.

A process is developed that combines soft lithographic molding with pulsed laser deposition (PLD) to make heteroepitaxial patterns of functional perovskite oxide materials. Micro‐ and nanostructures of sacrificial ZnO are made by micro molding in capillaries (MiMiC) and nano transfer molding, respectively, and used to screen the single crystalline substrates during subsequent PLD. ZnO is used because of its compatibility with the high temperatures reached during PLD and because of the ease of its removal after use by benefiting from its amphoteric nature. Sub‐micrometer sized lines of La0.67Sr0.33MnO3 are made by the transfer molding approach, preserving the anisotropic features expected for a fully oriented thin film and taking account for the magnetostatic contribution from the line shapes. Different patterns of SrRuO3 are made with lateral dimensions of a few micrometers having individual features for which electrical isolation is illustrated. The bottom‐up soft lithographic methods can be compliantly utilized for making epitaxial structures of various shapes and sizes in the μm down to the nm range, and offer unique opportunities for fundamental studies as well as for realizing technological applications.

Nanosheets of Ti0.87O2 and Ca2Nb3O10 were synthesized and transferred onto Si substrates by Langmuir-Blodgett deposition. Using pulsed laser deposition, SrRuO3 films were formed on top of these samples. The underlying nanosheets determined both the morphology and crystallographic orientation of the films. SrRuO3 grew preferentially in the [110]pc direction on Ti0.87O2 nanosheets, while growth proceeded in the [001]pc direction on Ca2Nb3O10 nanosheets (pc refers to the pseudocubic unit cell of SrRuO3). Besides macroscopic control over the out-of-plane crystal direction, single crystal orientations were measured by electron backscatter diffraction on the level of individual nanosheets, indicating that epitaxial growth was achieved on the nanosheets as imposed by their well-defined crystal lattices. The nanosheets also had a clear effect on the magnetic properties of the films, which showed anisotropic behavior only when a seed layer was used. A monolayer consisting of a mixture of both types of nanosheets was made to locally control the nucleation of SrRuO3. In this context, SrRuO3 was used as model material, as it was used to illustrate that nanosheets can be a unique tool to control the orientation of films on a (sub-)micrometer length scale. This concept may pave the way to the deposition of various other functional materials and the fabrication of devices where the properties are controlled locally by the different crystallographic orientations.

We have performed high field magnetotransport measurements to investigate the interface electron gas in a high mobility SrTiO3/SrCuO2/LaAlO3/SrTiO3 heterostructure. Shubnikov-de Haas oscillations reveal several 2D conduction subbands with carrier effective masses of 0.9me and 2me, quantum mobilities of order 2000 cm2/V s, and band edges only a few millielectronvolts below the Fermi energy. Measurements in tilted magnetic fields confirm the 2D character of the electron gas, and show evidence of inter-subband scattering.

This research presents an optimization of piezoelectric membrane actuators by maximizing the actuator displacement. Membrane actuators based on epitaxial Pb(Zr,Ti)O3 thin films grown on all-oxide electrodes and buffer layers using silicon technology were fabricated. Electrode coverage was found to be an important factor in the actuation displacement of the piezoelectric membranes. The optimum electrode coverage for maximum displacement was theoretically determined to be 39%, which is in good agreement with the experimental results. Dependences of membrane displacement and optimum electrode coverage on membrane diameter and PZT-film/Si-device-layer thickness ratio have also been investigated.

Long term storage of the pure commercial Zr(OtBu)4 in a sealed ampoule results in crystallization of a new high symmetry phase of Zr3O(OtBu)10 (1). Modification of Zr(OtBu)4 and Hf(OtBu)4 with 2,2,6,6,-tetramethyl-3,5-heptanedione (Hthd) produces dependent on the stoichiometry two types of derivatives, M(OtBu)2(thd)2 (2, 3) and M(OtBu)(thd)3 (4, 5) M=Zr(2, 4), Hf(3, 5), which have all been characterized by NMR and mass-spectral studies and for 4 and 5 also by complete X-ray single crystal studies. The latter failed for 2 and 3 in the view of their poor X-ray reflectivity. Addition of minor amounts of n-C5H11OH to 3 resulted in isolation of an unusual heteroleptic complex Hf2(OH)(OnC5H11)(OtBu)2(thd)4 (6). Thermal decomposition of compounds 1 and 3 in nitrogen atmosphere was studied for different thermal regimes by TGA-FTIR approach, revealing in all cases the formation of tetragonal ZrO2 and monoclinic HfO2 respectively, along with iso-butene, butanol and water for 1 and the same mixture including also Hthd for 3. Decomposition of 3 occurred always through intermediate melting, while higher heating rate for 1 permitted to achieve decomposition on in situ evaporation resulting in 3D hedgehog nanostructures according to SEM.

Angle-resolved photoemission spectroscopy (ARPES) is a powerful technique for the study of electronic structure, but it lacks a direct ability to study buried interfaces between two materials. We address this limitation by combining ARPES with soft x-ray standing-wave (SW) excitation (SWARPES), in which the SW profile is scanned through the depth of the sample. We have studied the buried interface in a prototypical magnetic tunnel junction La0.7Sr0.3MnO3/SrTiO3. Depth- and momentum-resolved maps of Mn 3d eg and t2g states from the central, bulk-like and interface-like regions of La0.7Sr0.3MnO3 exhibit distinctly different behavior consistent with a change in the Mn bonding at the interface. We compare the experimental results to state-of-the-art density-functional and one-step photoemission theory, with encouraging agreement that suggests wide future applications of this technique.

The synthesis of materials with well-controlled composition and structure improves our understanding of their intrinsic electrical transport properties. Recent developments in atomically controlled growth have been shown to be crucial in enabling the study of new physical phenomena in epitaxial oxide heterostructures. Nevertheless, these phenomena can be influenced by the presence of defects that act as extrinsic sources of both doping and impurity scattering. Control over the nature and density of such defects is therefore necessary, are we to fully understand the intrinsic materials properties and exploit them in future device technologies. Here, we show that incorporation of a strontium copper oxide nano-layer strongly reduces the impurity scattering at conducting interfaces in oxide LaAlO3-SrTiO3(001) heterostructures, opening the door to high carrier mobility materials. We propose that this remote cuprate layer facilitates enhanced suppression of oxygen defects by reducing the kinetic barrier for oxygen exchange in the hetero-interfacial film system. This design concept of controlled defect engineering can be of significant importance in applications in which enhanced oxygen surface exchange plays a crucial role.

The influence of sintering temperature on the polarization resistance of screen printed La2NiO4+delta (LNO) cathodes is studied. The electrode dispersion is measured on symmetrical cells with a 100 mu m 3% yttria-doped zirconia (TZ3Y) electrolyte and screen-printed yttria-doped ceria (YDC) barrier layers. The as-received commercial LNO powder was used in the formulation of the ink. For cathodes prepared following this procedure the optimum sintering temperature is 1000 degrees C. Analysis of the impedance spectra shows clearly a Gerischer dispersion (chemical impedance), with an activation energy of 124 kJ mol(-1) for the exchange rate parameter K-G. The addition of a dense LNO layer between electrolyte and porous electrode lowers the ASR by similar to 35%, showing a significant change in the oxygen transfer mechanism. A tentative model, based on a global two step oxygen exchange mechanism, is presented. There are also strong indications that surface diffusion of mono atomic oxygen is a major transport path. The electronic conductivity of LNO is too low at the intended operating temperature of similar to 600 degrees C, resulting in an additional resistance to the apparent electrolyte resistance. (C) 2013 Elsevier B.V. All rights reserved.

A combined experimental and theoretical investigation of the electronic structure of the archetypal oxide heterointerface system LaAlO 3 on SrTiO 3 is presented. High-resolution, hard x-ray photoemission is used to uncover the occupation of Ti 3 d states and the relative energetic alignment—and hence internal electric fields—within the LaAlO 3 layer. First, the Ti 2 p core-level spectra clearly show occupation of Ti 3 d states already for two unit cells of LaAlO 3 . Second, the LaAlO 3 core levels were seen to shift to lower binding energy as the LaAlO 3 overlayer thickness, n , was increased, agreeing with the expectations from the canonical electron transfer model for the emergence of conductivity at the interface. However, not only is the energy offset of only ∼ 300 meV between n = 2 (insulating interface) and n = 6 (metallic interface) an order of magnitude smaller than the simple expectation, but it is also clearly not the sum of a series of unit-cell-by-unit-cell shifts within the LaAlO 3 block. Both of these facts argue against the simple charge-transfer picture involving a cumulative shift of the LaAlO 3 valence bands above the SrTiO 3 conduction bands, resulting in charge transfer only for n (cid:2) 4. We discuss effects which could frustrate this elegant and simple charge-transfer model, concluding that although it cannot be ruled out, photodoping by the x-ray beam is unlikely to be the cause of the observed behavior. Turning to the theoretical data, our density functional simulations show that the presence of oxygen vacancies at the LaAlO 3 surface at the 25% level reverses the direction of the internal field in the LaAlO 3 . Therefore, taking the experimental and theoretical results together, a consistent picture emerges for real-life samples in which nature does not wait until n = 4 and already for n = 2 mechanisms other than internal-electric-field-driven electron transfer from idealized LaAlO 3 to near-interfacial states in the SrTiO 3 substrate are active in heading off the incipient polarization catastrophe that drives the physics in these systems.

After the discovery of the perovskite high T-c superconductors in 1986, a rare and almost unknown deposition technique attracted attention. Pulsed laser deposition (PLD), or laser ablation as it was called in the beginning, became popular because of the possibility to deposit complex materials, like perovskites, as thin film. By introducing in situ diagnostics and control of the laser fluence, PLD became a technique for several experimental studies of diverse complex materials. Nowadays, first steps towards industrial applications of PLD thin films on large wafers, up to 200 mm, are underway. In this paper we give a brief overview of the progress that PLD has made in our research group in Twente. Starting with control of deposition parameters, via in situ diagnostics with reflection high-energy electron diffraction and ending with the latest development in equipment for large-area deposition.

We have measured the Hall resistance and magneto-resistance (MR) of LaAlO3/SrTiO3 heterojunctions at magnetic fields up to 30 T in a temperature range T = 4 K to 70 K. For temperature below 7 K and above 50 K the devices display linear Hall resistance, indicating that one type of charge carriers dominate the transport. For temperatures between 10 K and 40 K, the Hall resistance is strongly non-linear, and is accompanied by a large positive MR, which is governed by the component of magnetic field normal to the interface. This behaviour in the intermediate temperature regime can be related to thermally activated high-mobility carriers.

This study demonstrates the significant impact of Cr-poisoning on the electrochemical operation of the LaNi0.6Fe0.4O3 (LNF) SOFC cathode under current load. Volatile Cr-species, originating from a porous metallic foam, enter the working electrode and modify both the LNF cathode layer and the Gd0.4Ce0.6O1.8 (GDC) barrier layer, causing increasing overpotential and cell impedance. The increase of the ohmic resistance is caused by a decrease of the in-plane electronic conductivity of the LNF layer combined with a deterioration of the ionic conductivity of the GDC barrier layer. The increase of the polarisation resistance is caused by a decrease of the electrochemical activity of the LNF surface towards oxygen reduction reaction at the triple phase boundary (TPB) due to Cr-incorporation in the outer shell of the LNF grains. Chemical reaction and electrochemically-driven reaction of volatile Cr-species with LNF and GDC contributes to the extrinsic degradation of the LNF cathodes under current load.

Epitaxial and atomically smooth ultra-thin SrCuO2 films are grown on SrTiO3 substrates using pulsed laser deposition. The structural and chemical aspects of these single-layer films of various thickness are characterized using in situ X-ray photoelectron diffraction (XPD) and photoelectron spectroscopy. By comparing XPD scans to multiple-scattering electron diffraction simulations, we demonstrate a structural transformation from bulk-planar to chain-type SrCuO2 as the film thickness is reduced from 9 to 3 unit-cells. This observation is in agreement with the recent theoretical prediction [Z. Zhong, G. Koster, and P. J. Kelly, Phys. Rev. B 85, 121411(R) (2012)] and opens new pathways for structural tuning in ultra-thin films of polar cuprates.