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Environment-friendly ferroelectric Mn:BST//Mn:BZT heterostructures were epitaxially deposited on (001) MgO substrates by pulsed laser deposition with different combination ratios of Mn:BST over Mn:BZT, 2.5:7.5; 1:1; and 7.5:2.5. The microstructural studies indicate that the in-plane interface relationships between the heterostructures and the substrate are determined to be (001)Mn:BST//(001)Mn:BZT//(001)MgO and [100]Mn:BST//[100]Mn:BZT//[100]MgO. The Ku band microwave (15.5–18 GHz) dielectric property characterizations show that the dielectric constant, dielectric loss, and tunabilities of the heterostructures are highly dependent upon the sequences of Mn:BST to Mn:BZT. The optimized dielectric tunability with a low loss tangent was found to be 58.1%–74.4% under the combination ratio of 1:1 for Mn:BST to Mn:BZT, which suggests that the as-grown ferroelectric heterostructures can be developed for room temperature tunable microwave elements and related device applications.

The transport properties of double perovskite LaBaCo2O5.5+δ thin films with different thicknesses were systemically studied. A thin (7 nm in thickness), disordered LaBaCo2O5.5+δ layer was formed at the interface between the film and substrate. The films had a typical semiconductor behavior with antiferromagnetic and ferromagnetic behavior coexisting at low temperature. Although the Curie temperature was independent of the film thickness, the coercive fields and magnetizations increase with increasing the film thickness. An ultra large magnetoresistance effect value of about 44% was obtained at 60 K for the film of 82 nm.

Symmetric half cell structures of highly epitaxial PrBaCo2O5+δ (PBCO)/Gd0.8Ce0.2.2O2:Y0.08Zr0.92O2/PrBaCo2O5+δ thin films were designed and fabricated on (001) LaAlO3. Microstructural studies indicate that the multilayer films have excellent single-crystal quality and epitaxial nature. The electrochemical impedance spectroscopy measurements reveal that the PBCO film electrodes have a polarization resistance as low as 0.109 Ω cm2 at 597 °C in air and an ultrafast surface exchange coefficient (0.006 cm/s at 598 °C) with low activation energy (0.77 eV). The low polarization resistance and rapid surface oxygen exchange kinetics suggest that the PBCO can be an excellent cathode material for intermediate-temperature solid oxide fuel cells.

Using reflection electron microscopy (REM), transmission electron microscopy (TEM), and Nomarski optical microscopy we obtained direct evidence that local surface strain-fields, originated from misfit dislocations, are responsible for the formation of morphological crosshatches during molecular beam epitaxy of lattice mismatched InGaAs/GaAs layers. A mechanism is proposed to correlate the formation of the crosshatched patterns with the variation of the growth rate across the epitaxial surface under the perturbation of network shaped strain-fields in the surface.

Nonorthogonal twinings have commonly been observed in perovskite oxides such as SrTi03 and BaTi03. Among them, the ﹛111﹜ Σ3 type twining exists with a relative large amount of population and has been extensively studied. By combining quantitative high resolution transmission electron microscopy (HRTEM) and spatially resolved electron energy loss spectroscopy (EELS), one was able to determine the atomic structure of the ﹛111﹜Σ3 twin boundary in these oxides.[l] On the other hand, nonorthogonal twinings in SrRuO3 have been much less studied. SrRu03, a ternary ruthenium metal oxide, has a perovskite-compatible structure and exhibits low electrical resistivity (10-4 Ω•cm), showing an unparallel technique importance in microelectronic applications. Since the properties of material strongly depend on the microstructure and defect configurations, it is important to study the twining structures and their formation mechanisms in SrRuO3 thin films.Transmission electron microscopy (TEM) was used to study the SrRuO3 thin films grown on (001) LaAlO3 by 90° off-axis rf sputtering.

ZnO films embedded with Ag nanoparticles are deposited at 750 °C with a reactive radio-frequency magnetron sputtering. The films are found to have a large enhancement in the intensity of photoluminescence emission and in the extinction of incident light. The enhancement is assigned to be from the interaction between the localized surface plasmons in the Ag nanoparticels and the light. The surface plasmons in the films can be excited in a wide range, from ultraviolet to near infrared wavelength of light.

This research was partially supported by Department of Energy under Grant No. DE-FG26-07NT43063, the National Science Foundation under Grant No. NSF-NIRT-0709293, the Texas ARP Program under Grant No. 003656-0103-2007, the State of Texas through the Texas Center for Superconductivity at the University of Houston, and the South Texas Technology Management Program.

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The (LaBa)Co2O5+δ thin films were grown on (001) SrTiO3 single crystal substrates by using pulsed laser deposition. Microstructure studies from x-ray diffraction and electron microscopy show that the films have good epitaxial quality with a-axis orientation and sharp atomic interface. Transport property and isothermal magnetoresistance measurements have been used to understand the physical properties of the films with anomalous magnetic phenomena and the largest reported magnetoresistance value of 19% at 40 K.

Due to their unique dielectric and ferroelectric properties, ferroelectric superlattices have attracted increasing interest for fundamental and applied research. Such superlattices with a small layer thickness (a few unit cells) provide a model system to investigate the effects of crystal size, internal strain, interfacial structure and chemistry on physical properties. Recent development in oxide thin film epitaxial growth using reactive molecular beam epitaxy (MBE) make it possible to grow high quality metastable oxide superlattice films. BaTiO3 / SrTiO3 system has been selected for this study.[(BaTiO3)5 / (SrTiO3)5]20 superlattice films were grown on (001) SrTiO3 substrates by reactive MBE. The atomic structure of these films and the related heterostructural interfaces have been investigated by a combination of high-resolution transmission electron microscopy (HRTEM) and computer image simulations. HRTEM studies were conducted within JEOL-4000EX electron microscope equipped with Gatan Image Filter (GIF), which is operated at 400 kV.

Austenitic stainless steels plasma-nitrided at low temperature can have a tremendously improved surface hardness without affecting their excellent corrosion resistance. The surface layer of these nitrided materials was considered to be composed of an uncharacterized, so called “S-phase”. During the past decade, several research groups have studied “S” phase using X-ray diffraction and transmission electron microscopy (TEM), but its microstructure is not yet well understood and is still a topic of debate. In this paper, we characterize the microstructure of 316 stainless steel nitrided by intensified plasma-assisted processing (IPAP) using cross-sectional TEM.Samples of 316 austenitic stainless steel were nitrided for 1 hour by IPAP at a temperature of ∼ 400 °C. Plasma-nitrided samples were cross-sectioned and glued face-to-face by joining the nitrided surface. Crosssectional specimens for TEM observations were prepared by mechanical grinding, polishing and dimpling followed by Ar+ milling. TEM studies were carried out in a newly installed JEOL JEM 2010 electron microscope in the Materials Characterization Facility at the Louisiana State University.

TiSiN coatings were deposited by using a large area filtered arc deposition technique from TiSi targets with different Si content. The influence of the Si content in the targets on the surface morphology, composition, bonding structure, crystalline structure and internal stress of the TiSiN coatings were systematically studied by using scanning electron microscopy, x-ray photoelectron spectroscopy, x-ray diffraction and the substrate curvature method, respectively. It was found that by increasing Si content in the TiSi targets to 20?at%, the Si content in the coatings increases linearly to 7.7?at%. Both XRD and XPS results indicate that all the TiSiN coatings consist of a nanosized TiN phase and an amorphous Si3N4 phase except for the coatings with Si content of above 4.5?at%, in which 5% of amorphous TiSi2 phase exists. With increasing Si content in the coating, the coatings change orientation from the (1?1?1) to the (2?2?0) preferred orientation. The TiN grain size decreases linearly to 5.4?nm with an increase in Si content up to 4.5?at%, and then increases slightly with a higher Si content in the coatings. The substrate curvature method shows that the increase in the Si content from 0 to 4.5?at% results in a rapid increase in the internal stress in the coating from 2.2 to 3.9?GPa, but a further increase in the Si content leads to a slight decrease in the internal stress in the coating. The decrease in the grain size with increasing Si content contributes to the increase in the internal stress in the TiSiN coatings.

Domains and discommensurations have been directly observed by transmission electron microscopy in some dark-field images using certain reflections in a Mn-Si-Al octagonal quasicrystal. The invisibility and visibility of domains and discommensurations separate the diffraction spots into basic and satellite reflections. The domains and discommensurations observed in satellite reflections are interpreted as due to the ordering of Si and Al atoms in the quasilattice of the quasicrystal. A simple model which gives satisfactory agreement with the experimental results is given.

Bismuth titanate (Bi4Ti3O12) belongs to a family of layered perovskites (Aurivillius phases) that are important for nonvolatile ferroelectric memory applications. Recently epitaxial (001) Bi4Ti3O12 thin films have been grown on (001) SrTiO3 by reactive molecular beam epitaxy (MBE) in an adsorptioncontrolled growth regime. Bi4Ti3O12 has a monoclinic layered perovskite structure at room temperature which consists of alternating Bi2O2 and Bi4Ti3O10 perovskite layers (see the upper part of Fig. 1(b)). Due to the significant difference in crystal structure between film and substrate, the surface termination of the SrTiO3 substrate and the way in which growth is initiated might be expected to have a significant influence on the interfacial structure. In this work, we present high-resolution transmission electron microscope (HRTEM) studies of the Bi4Ti3O12 / SrTiO3 interfacial structure for Bi4Ti3O12 films grown on SrTiO3 substrates terminated with either the TiO2- or SrO-layers.Bi4Ti3O12 thin films were grown on SrO- or TiO2-layer terminated homoepitaxial SrTiO3 buffer layers grown on SrTiO3 (001) substrates by reactive MBE.

The n+1TinO3n+1 Ruddlesden-Popper homologous series are promising candidates in the search for low loss tunable dielectric materials. SrTiO3 (n=∞) has the perovskite structure with alternating TiO2 and SrO layers. However, those members of the n+1TinO3n+1 series with n≠∞ have tetragonal symmetry and space group 14/mmm. These phases are formed by inserting a rock-salt SrO layer every n SrTiO3 perovskites, resulting in a successive perovskite blocks being mutually sheared by [1/2,1/2,0] (Fig. 1).Previously, the n = 1 - 3 members of this series have been made in polycrystalline form using solid state synthesis methods. Attempts to synthesize intermediate members (4≤nn+1TinO3n+1, RP series with n = 1 - 5 have been synthesized using reactive molecular beam epitaxy (MBE).

A series of TiN/Ti multilayer coatings with fixed TiN layer thickness and different Ti layer thicknesses were deposited using a large area filtered arc deposition technique. X-ray diffraction was used to investigate the crystalline structure, lattice strain, and crystallinity of the deposited coatings. A substrate curvature method was used to measure the internal stress in the multilayer coatings. The influence of the Ti interlayer thickness on the crystalline structure and internal stress in the coatings was systematically studied. It was found that a cubic TiN phase and hexagonal Ti phase exist in all the multilayer coatings. The TiN and Ti layers in the multilayer coatings exhibit a strong (111) and (002) preferred orientation, respectively. With the increase in the Ti layer thickness, the d-spacing decreases and the peak width increases for both TiN (111) and Ti (002) peaks, indicating a decrease in the lattice strain and an increase in the crystallinity of both TiN and Ti phases. It is suggested, tha...

Co nanostructures in carbon films synthesised by dual electron beam evaporation were studied by TEM and XPS. Thin films with low Co-content (∼9 at.%) are mainly amorphous with the Co atoms dispersed in the C matrix forming an atomic scale nanocomposite. The films with intermediate Co-content (29?63 at.%) are composed of a Co nanoparticles embedded in the amorphous carbon-rich matrix. Thin films with high Co-content (79 at.%) consist of sandwiched Co2C and α-Co nanoparticles that are embedded in an amorphous Co-rich matrix. The microstructure development of the nanostructures as a function of the Co-content is presented.

Co/Diamondlike Carbon (DLC) nanocomposite films consisting of well-defined, self-organised nanopillars were successfully fabricated by plasma-assisted magnetron sputtering. The nanopillars were identified as a defect-rich e-Co structure. The shape of such nanopillars is stable up to 350?C and dissociates into several nano particles at 500?C. The defective e-Co structure of the nanopillars is stable up to 250?C and then transforms into: polycrystalline δ'?Co2C at 300?C; a textured structure of lamellar δ'?Co2C and α-Co with a minor phase of Co3C at 350?C; α-Co at 500?C. The underlying processes in this nano scale manufacturing are discussed.

The ferroelectric, ferromagnetic, and magnetoelectric properties of (1- x) Pb( Zr0.52Ti0.48)O-3 - xNiFe(1.9)Mn(0.1)O(4) (PZT- NFM) ceramic composites were found to be dependent upon postsinter annealing and aging. It was found on annealing and aging that (i) the size and density of the NFM phase is reduced, (ii) the PZT lattice constants changed from (a=3.8 angstrom, c= 4.07 angstrom) to (a= 4.07 angstrom, c= 4.09 angstrom), (iii) the ferroelectric and ferromagnetic Curie temperatures decreased by 8 and 33 degrees C, respectively, and (iv) the magnetoelectric coefficient increased by 50%. (C) 2007 American Institute of Physics. Office of Basic Energy Science, DOE, DE-FG02-06ER46288

Ferroelectric BaTiO3 (BTO) thin films were deposited on NiO buffered polycrystalline Ni tapes by pulsed laser deposition. Microstructural studies by x-ray diffractometer and transmission electron microscopy reveal that the as-grown BTO films have the nanopillar structures with an average size of approximately 80nm in diameter and the good interface structures with no interdiffusion or reaction. The dielectric and ferroelectric property measurements exhibit that the BTO films have a relatively large dielectric constant, a small dielectric loss, and an extremely large piezoelectric response with a symmetric hysteresis loop. These excellent properties indicate that the as-fabricated BTO films are promising for the development of the structural health monitoring systems.

This letter reports the structural characteristics of the self-assembled surface nanostructure in the 0.75wt% (Zr0.88Ce0.12)O2–0.25wt% (La0.8Sr0.2)MnO3 ceramics. The surface consists of periodic porous network with islandlike structures occurring at the triple boundary junctions. The pores were found to have the diameter in the range of 150–200nm with the thickness of the porous surface layer of the order of 100nm. The pore distribution was quasiperiodic with the spacing in the range of 50–150nm. The formation of the nanoporous network is correlated to the structural transformation occurring in ZrO2 system.

The interface of epitaxial (Pb0.35Sr0.65)TiO3 films on MgO substrates grown by pulsed laser ablation was studied using transmission electron microscopy (TEM). Cross-section TEM studies revealed that the epitaxial films have a lattice mismatch of −6.2% with respect to the substrates. Electron diffraction pattern and high-resolution TEM image of the plan-view (Pb0.35Sr0.65)TiO3∕MgO interface present evidence of a modulated structure on the film plane. This allowed obtaining the actual lattice mismatch of −7.14% at the interface. Plan-view TEM of the interface is able to provide fundamental information that cannot be obtained by the cross-section TEM alone, and its advantages in studying such epitaxial films are addressed.

Ferroelectric superlattices have been actively and intensively studied in recent years for their great scientific and technological interest. Superlattice containing Pb-based ferroelectric layers are important among ferroelectric superlattice systems, however, it is difficult to grow such superlattice due to the high volatility of Pb. Recently, great progress has been made in fabricating superlattice structure of PbZrO3/PbTiO3 by multi-ion-beam sputtering’ and molecular beam epitaxy (MBE). In this paper, we report the microstructural investigations of PbTiO3/SrTiO3 superlattice films, which were epitaxially grown on the SrTi03 substrate by MBE, using transmission electron microscopy (TEM).[(PbTiO3)l0/(SrTiO3)l0]15 superlattice films were stacked on (100) SrTiO3 substrate alternately by MBE. Before growing the superlattice structure, a baffle layer including the 1000Å La-doped SrTi03 and the subsequent 500 Å PbTiO3 thin films was grown on the substrate. Above the PbTi03/SrTi03 superlattices, another PbTi03 thin film (1000 Å) was grown. Cross-section TEM specimens were prepared by standard methods.

Epitaxial thin film of SrRuO3 is very useful in device applications, due to its important electrical and magnetic properties. For example, (Pb,Zr)TiO3 ferroelectric capacitors with SrRuO3 thin film electrodes exhibit superior fatigue and leakage characteristics. Epitaxial SrRuO3 thin films grown on different substrates, such as on (001) SrTiO3 and (001) LaA1O3, have different magnetic properties, owing to the different microstructures in the film. Microstructures in epitaxial SrRuO3 thin films grown on (001) SrTiO3 have been studied in our previously work. In this paper, microstructure of epitaxial SrRu03 thin films grown on (001) LaA103 is reported.SrRuO3 thin films on (001) LaA1O3 were deposited by 90° off-axis sputtering. For cross-section TEM studies the SrRuO3/LaA1O3 heterostructural samples were cut along the [100] direction of LaA103. The cut slides were glued face-to-face by joining the SrRu03 surfaces. Plan-view and cross-section TEM specimens were prepared by mechanical grinding, polishing and dimpling, followed by Ar-ion milling.

High-temperature catalysts containing Pd supported on high-surface area ceria-zirconia are optimum materials for fuel economy when automotive engines operate under high speed or load conditions. A prerequisite for developing such thermally stable catalysts is to gain a good understanding of the thermal deactivation modes contributing to the aging and degradation of catalysts in harsh thermal environments. It was discovered by X-ray diffraction that upon hightemperature aging, Pd may sinter into large (about 10 nm diameter) particles and become encapsulated in the ceria-zirconia. To confirm this conclusion, a prototype high-temperature catalyst containing Pd supported on high-surface area ceria-zirconia, aged at temperature above 1100 °C is studied by transmission electron microscopy (TEM).The ceria-zirconia supported Pd (0.25 wt%) catalyst was aged at 1105 °C and calcined at 700 °C for 2 h. For TEM sample preparations, first of all, a large-size aggregate with diameter about 1 mm was selected and sandwiched between by two pieces of silicon crystal.

It is widely believed that the stress in the epitaxial thin films, caused by the lattice mismatch between the thin film and substrate, has a strong influence on the properties. For example, lattice strained epitaxial thin films of SrRu03 grown on (001) SrTiO3 demonstrated magnetic and electrical properties different from those in bulk materials.1 In this paper, we report the effect of strain relaxation of the thin film on microstructure by means of transmission electron microscopy (TEM).SrRuO3 thin film on a vicinal (001) SrTiO3, with a miscut angle 0.9° and miscut direction 5.7° away from the in-plane [100] axis, was grown by 90° off-axis sputtering. Cross-section and plan-view TEM specimens were prepared following the procedure described in Ref. 2. TEM investigations were conducted in a Philips CM 12 microscope in the EMAL at the University of Michigan.X-ray diffraction studies of the as-grown SrRu03 thin film using a four-circle diffractometer showed that the film consists of a single [ 110]-type domain structure.

A short-period (BaTiO3)6∕(SrTiO3)5 superlattice was characterized by x-ray diffraction and transmission electron microscopy. The superlattice is epitaxially oriented with the c axes of BaTiO3 and SrTiO3 normal to the (001) surface of the SrTiO3 substrate. Despite the large in-plane lattice mismatch between BaTiO3 and SrTiO3 (∼2.2%), the superlattice interfaces were found to be nearly commensurate. The crystallographic c∕a ratio of the superlattice was measured and the results agree quantitatively with first-principles calculations and phase-field modeling. The agreement supports the validity of the enhanced spontaneous polarization predicted for short-period BaTiO3∕SrTiO3 superlattices.

Ferroelectric Ba0.6Sr0.4TiO3 thin films with 2% Mn additional doping were grown on (001) MgO by pulsed laser deposition. The microstructural studies from x-ray diffraction and transmission electron microscopy indicate that the films are highly epitaxial with c-axis oriented and atomic sharp interface. Dielectric property measurements at 1 MHz and room temperature reveal that the as-grown films have outstanding dielectric properties with large tunability of 80% at 40KV∕cm, very large dielectric constant value of 3800, and extra low dielectric loss of only 0.001. The high frequency (10–30 GHz) dielectric measurements demonstrate that the films are excellent in both dielectric property and very low dielectric insertion loss. Compared with the pure BSTO films or traditional doping, the additional doping of Mn in BSTO thin films can significantly improve the dielectric property of the as-grown films.

Ferroelectric Pb0.35Sr0.65TiO3 (PSTO) thin films were grown on (001) MgO by using pulsed laser deposition. Microstructure studies from x-ray diffraction and electron microscopy indicate that the as-grown PSTO films have excellent single crystal quality and good epitaxial behavior with their c-axis oriented perpendicular to the plane of the films. The interface relationships between the PSTO films and MgO were determined to be [100]PSTO∕∕[100]MgO and (001)PSTO∕∕(001)MgO. The high frequency dielectric property measurements (up to 20 GHz) reveal that the as-grown films have a high dielectric constant value above 1420 and very large dielectric tunability above 34% at room temperature. These results suggest that the as-grown PSTO thin films on MgO are a good candidate for developing room-temperature high-frequency tunable microwave elements.

Self-organized, three-dimensional (3D), coherent fluorite Gd2Zr2O7 nanorods were synthesized with pulsed-laser ablation. Transmission electron microscopy studies reveal that the 3D nanorods are epitaxially grown on (001) LaAlO3 with (001)GZO‖(001)LAO, [110]GZO‖[100]LAO and [11¯0]GZO‖[010]LAO. The nanorods have in-plane dimensions of about 20–35 nm, and their length can extend for the entire film thickness. The 3D nanorods have a vertical prism shape with side surfaces exhibiting a serrated morphology composed of {111} planes. The formation of such self-organized nanorods is consistent with a preferential growth mechanism and surface energy minimization considerations.

CTAB (Cetyltrimethylammonium bromide) stabilized cobalt nanoparticles of three different sizes between 5.5 and 11 nm diameter were prepared using reverse-micelle method. Their geometric and electronic structure was characterized using X-ray Absorption Spectroscopy (XAS) at the Co-K-edge and Transmission Electron Spectroscopy (TEM). The as-prepared nanoparticles appear to have a cobalt core that is a mixture of the Co-α and β-phase and a shell, possibly, made of a cobalt(III) octahedral complex. The shell disappears when the particles are annealed to 250 °C and the particles are transformed into the standard hcp (α) phase. The short time stability of the particles against oxidation supports the presence of a core-shell structure with a Co core and a protective shell. A longer exposure to air leads to a more or less complete oxidation of the entire particle to CoO.

The electrodeposition of the FeCoNiCu quaternary system onto a rotating disk electrode was explored in order to prepare compositionally modulated multilayers. Multilayers having a different layer thickness were electrodeposited by a pulse current method and the structure was determined with transmission electron microscopy and X-ray diffraction. When the multilayer alloy thickness was larger than 10 nm, the deposit grain size was found to be a function of the Co-rich layer thickness. Below an alloy thickness of 10 nm, the Cu layer size was correlated with a preferred deposit orientation. Giant magnetoresistance was also observed for this electrodeposited quaternary system for the first time.

Nitrided austenitic 316 stainless steel produced by intensified plasma assisted processing has been studied by transmission electron microscopy (TEM), high-resolution TEM, and image simulation techniques. Cross-sectional TEM studies showed that the nitride layer is composed of a single phase that was found to possess a simple cubic structure. This nitride is produced by introducing one N atom into one of the interstitial sites of the octahedra within the unit cell of the γ-austenite. The lattice constant of the nitrided simple cubic structure was determined to be a=3.78 A, which is expanded by about 5.4% from that of austenite. Stacking faults, antiphase domains, and antiphase domain boundaries in the nitride layer were observed using dark-field and high-resolution TEM imaging. The evolution of the nitride phase seems to be preceded by lattice expansion and formation of stacking faults due to the presence of N and is consistent with the observed lattice constant reduction with depth.