bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ferroelectric Bi4Ti3O12–SrBi4Ti4O15 Intergrowth Thin Films Prepared by Pulsed Laser Deposition
Authors: Shibuya Akira , Noda Minoru , Okuyama Masanori 
Published: April 2011

ABSTRACTC axis-oriented Bi4Ti3O12–SrBi4Ti4O15 (B IT-SB Ti) intergrowth epitaxial ferroelectric thin films have been grown by pulsed laser deposition (PLD) method on MgO (001) and SrTiO3 (001) substrates. The epitaxial growth of BIT-SBTi intergrowth thin films were confirmed by X-ray diffraction (XRD) θ-2θ scan, pole figure plots and reciprocal space mappings. The c axis lattice constant of the BIT-SBTi intergrowth thin film is very close to that of made up of regular stacking of one-halves of the unit cells of Bi4Ti3O12 (3.296 nm) and SrBi4Ti4O15 (4.189 nm). The annealed BIT-SBTi thin film on Pt/Ti/SiO2/Si substrate shows intergrowth structure, too, and exhibits superior ferroelectricity that the values of 2Pr and 2Ec are 32.0 μC/cm2 and 190 kV/cm, respectively. The annealed BIT-SBTi film shows that the degradation of switching charge after 1×1010 switching cycles was 16.5%. This ferroelectric enhancement is attributed to strain of pseudo-perovskite layers interacting through Bi2O2 layer. The dielectric constant and dielectric loss of the annealed BIT-SBTi film were 433 and 0.037, respectively.
Field Induced Dielectric Properties of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 Thin Films
Authors: Laha Apurba , Saha S. , Krupanidhi S. B. 
Published: April 2011

ABSTRACTDC electric field induced dielectric properties of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) thin films were studied as a function of frequency at different temperatures. It was observed that the dielectric constant (ε) and dissipation factor (tanδ) were decreased in presence of bias field. The temperature of dielectric maxima was found to increase with increasing bias level. The low temperature (<Tm) frequency dispersion of dielectric permittivity was suppressed with the application of dc bias. After a certain bias voltage the relaxor property of films was disappeared i.e. the films exhibited normal ferroelectric behavior. Since the absence of long range interaction among the nanopolar clusters in PMN and its family is believed to be the origin of relaxor behavior, disappearance of relaxor nature in PMN-PT (70/30) films could be attributed to manifestation of long-range order at higher bias voltage. This was observed in the temperature dependence of dielectric constant i.e. the films neither exhibited any frequency dispersion in the temperature of dielectric maximum (Tm) nor showed any diffused phase transition. The relaxor property of PMN-PT thin films was studied in terms of diffused phase transition together with frequency dispersion of the temperature of dielectric maximum (Tm). Vogel-Fulcher relation was used to analyze the frequency dependence of temperature of dielectric maximum.
Top Electrode Area Dependence on Displacement Property of Lead Zirconate Titanate Films Prepared by Chemical Solution Deposition Process
Authors: Iijima Takashi , Ito Sachiko , Matsuda Hirofumi 
Published: April 2011

ABSTRACTEffects on ferroelectric and piezoelectric properties of top-electrode diameter variance from 80 to 8 μm were investigated using an AFM probing system connected with a ferroelectric test system with bipolar and unipolar signals at 5 Hz. The Pt and 1.2-μm-thick PZT layers were etched off to prepare Pt top electrode etched samples or Pt/PZT stack etched samples. In the case of bipolar measurement, the top electrode diameter did not affect ferroelectric properties, while the maximum displacement of the butterfly-shaped hysteresis curve, related with piezoelectric response, increased with decreasing top-electrode diameter. On the other hand, the longitudinal piezoelectric constant, AFM d33, calculated from the strain curve slope at 5 Hz, +5 V, increased with decreasing top-electrode diameter. The average value of the Pt/PZT stack-etched AFM d33 almost equals that of Pt-etched AFM d33. Average AFM d33 of the 8-μm-diameter Pt-etched and Pt/PZT stack-etched samples are 129 and 135 pm/V, respectively.
PMN-PT thin films: Electromechanical behaviour, polarisability and microstructure
Authors: Donnelly N. J. , Catalan G. , Morros C. , Bowman R. M. , Gregg J. M. , Kighelman Zian , Damjanovic Dragan , Setter Nava 
Published: April 2011

ABSTRACTThin film capacitor structures of Pb(Mg1/3Nb2/3)O3 (PMN) - PbTiO3 (PT) were fabricated using pulsed laser deposition (PLD) on MgO{100} substrates using (La1/2,Sr1/2)CoO3 (LSCO) as a lower electrode. Crystallographic and dielectric characterisation confirmed perovskite relaxor-like behaviour. Measurements of the electrostrictive coefficients by in-situ X-ray diffraction, piezo-response atomic force microscopy and three point bending experiments showed both Q11 and Q13 to be comparable to accepted values for single crystals. However, for a given field, the electric field-induced strain in the thin films was much less than that of single crystal. This was clearly intimately linked to poor thin film polarisability. Previous work had shown sol-gel PMN-PT films to have significantly greater permittivities than PLD films, and a TEM investigation was undertaken to see if functional differences could be related to differences in microstructure, and hence if the functional and electromechanical properties of PLD films could be improved by attempting to replicate sol-gel microstructures.
Positive Temperature Coefficient of Resistance in MOCVD (Ba0.75Sr0.25)Ti1+yO3+z Films
Authors: Saha S. , Kaufman D. Y. , Streiffer S. K. , Erck R. A. , Auciello O. 
Published: April 2011

ABSTRACTThe leakage and dielectric properties of a thickness series (90–480 nm) of {100} fiber-textured MOCVD (Ba0.75Sr0.25)Ti1+yO3+z (BST) thin films on Pt/SiO2/Si were investigated. The temperature and voltage dependence of the permittivity were consistent with previous observations, where thinner films demonstrated a suppressed temperature and electric field response that transitioned to a more bulk-like response with increasing film thickness. The current-voltage characteristics showed two distinct regimes. At low fields the current displayed weak field dependence and a monotonic increase with increasing temperature. In contrast, positive temperature coefficient of resistance (PTCR) was observed in the high-field leakage current behavior. The PTCR behavior was more pronounced for thicker BST films. Factors contributing to the observed PTCR effect are outlined and contrasted with the description for bulk BaTiO3 ceramics.
Hardness and modulus of CrNx coatings
Authors: Janssen G. C. A. M. , Hoy R. , Kamminga J.-D. 
Published: April 2011

ABSTRACTTwo series of CrNx coatings have been deposited in an industrial PVD set-up. It is shown that for an increased ion bombardment on the growing film the hardness (H) and Young's modulus (E) are independent on composition. For these hard coatings the elastic strain to failure or plasticity limit (H/E) is 0.11. The coating fails long before it is stretched to its plasticity limit. Deformation of the coating by 1% already leads to crack formation. It is argued that the cause of this failure is the low work of fracture of the coating combined with flaws in the coating.
Microindentation of Coarse-Grained Polycrystalline α-Brass
Authors: Zhang Nian , Xie Changjin , Tong Wei 
Published: April 2011

ABSTRACTEffects of the indent depth, the distance between the indent and the grain boundary, grain sizes, and crystallographic orientations on the microhardness of annealed coarse-grained polycrystalline α-brass were investigated using a Vickers indenter with indents much smaller than the α-brass grains (ranging from 80 μm to 550 μm). It is found that the microhardness of α-brass crystals shows a strong dependence on the indentation depth when it is smaller than 5 μm and a very weak dependence on both the distance between the indent and the grain boundary and the grain size when the indentation depth is about 5 μm and more. No significant dependence of the microhardness on the crystallographic orientations was observed in the fourteen grains of different orientations studied in this investigation.
Processing and Characterization of CVD c-BN Films and c-BN/Diamond Bilayers
Authors: Yang Tien-Syh , Cheng Jong-Bin , Wong Ming-Show 
Published: April 2011

ABSTRACTThe paper reports the syntheses of c-BN films by the reaction of B2H6 and NH3 in the hydrogen and argon mixture using microwave plasma-assisted chemical vapor deposition (MPCVD). The effects of NH3/B2H6 ratios, hydrogen addition, pulsed-DC substrate-bias voltage and diamond as bufferlayer on the formation of c-BN were investigated. As-grown films are characterized by FTIR, grazing-incidence XRD, and SEM. The NH3/ B2H6 = 3 was selected to obtain a better crystallized BN films with moderate deposition rate. When the hydrogen content was at 85 vol.% in the gas mixture and the substrate bias at −200 V, the maximum c-BN content about 65 % was obtained. However, the film was easily cracked in a few hours. The film deposited at lower substrate biasing of −100 V could preserve for a few days without peeling off, although it had lower c-BN content about 40 %. Nanocrystalline diamond film, deposited from 1 vol.% CH4/Ar plasma, as bufferlayer can promote the heteroepitaxial growth of c-BN, resulting in 80 % c-BN content. The c-BN/diamond bilayer were adherent with a total thickness of 1.2 μm.
Nanoindentation induced crack morphologies in nanostructured hard thin films
Authors: Karimi A. , Santana A. E. , Cselle T. , Morstein M. 
Published: April 2011

ABSTRACTCrack formation in hard thin films and the influence of nanostructuring on nucleation and propagation of different crack types were studied using TiAlSiN-based multicomponent nitrides. Thin films of about 2 μm thickness were deposited onto tungsten carbide-cobalt substrates using cathodic arc PVD method. By rotation of samples and changing deposition parameters and chemical composition of target materials, various nanostructured thin films were obtained including: nanocomposite films made of nanocrystallites about 10–30 nm, chemically modulated layers with the bilayer thickness at the range of 10 nm, iso-structured TiAlN/TiAlSiN multilayers with variable bilayer thickness, and finally monolithic single layer with columnar structures of different size. Depth sensing nanoindentation was used to measure hardness and modulus of thin films and to activate several failure modes in order to provide an estimation of the fracture toughness and interfacial fracture energies. Morphology of cracks mainly consist of successive microcracks nucleated at the contact edge periodically under stretching tensile stress upon displacement of indenter. These cracks are almost straight, parallel to each other, regularly distributed at the contact site in fine structure films. They appear discontinuous and irregular in coarse columnar monolithic and in multilyers with larger bilayer periods. The annular cracks appear at greater loads due to tensile peaks caused by bending stresses generated from the substrate depression and coating deflection. These can be accompanied by the interface fracture and delamination. The radial cracks emanating from the corner of indenter appear in high stress films and extend to the neighbouring zones of the contact area. In addition to geometrical cracks, nanoscale cracks frequently appear around the contact area leading to the formation of small discontinuities on the load-displacement curves.
Ion-Assisted Adhesion Treatments for MoS2-Metal Alloy Solid Lubricating Coatings
Authors: Savan Alan , Spassov Vladislav , Gerbig Yvonne , Haefke Henry , Munnik Frans , Mikhailov Serguei 
Published: April 2011

ABSTRACTAdhesion layers are well-known to significantly improve the lifetime of MoS2-based solid lubricants. Typically, adhesion layers are “optimized” based on a phenomenological tests and then their deposition parameters are held fixed while the functional coating is studied. Here we examine the adhesion layer itself, while holding an MoS2 layer constant. In particular, the critical interfaces between the adhesion layer and the substrate, and between the adhesion layer and functional coating are regarded. MoS2-metal solid lubricant is chosen as the functional layer because it is a relatively brittle material whose performance is significantly affected by the quality and type of adhesion treatments. Substrate surface sputter cleaning was done by cathodic arc evaporation with different arc energies and substrate bias voltages. In addition to sputter etching of any surface oxides or other contaminants, some level of shallow implantation might be expected. The more usual surface preparation technique of argon plasma sputter etching was also used for comparison. Chromium and titanium were tested as adhesion layer materials. The adhesion layer thickness and deposition pressure were varied. Rutherford backscattering spectroscopy (RBS) and transmission electron microscopy (TEM) were used to analyze the adhesion layers and their interfaces with the substrates and with the MoS2-metal coatings. Ballon-disk tribometer sliding wear tests were made to assess changes in solid lubricant performance coming from variations in the adhesion layer. Scratch test characterizations were made to further evaluate adhesion layer performance.
Towards the Industrialization of Superhard Nanocrystalline Composites for High Speed and Dry Machining
Authors: Jilek Mojmir , Holubar Pavel , Veprek-Heijman Maritza G. J. , Veprek Stan 
Published: April 2011

ABSTRACTNovel superhard wear resistant nanocomposite coatings nc-(Ti1-xAlx)N/a-Si3N4 for advanced machining tools were developed and introduced into large scale industrial production within a relatively short time. We describe the development of the coating technology based on vacuum arc evaporation from a specially designed cylindrical cathode and, as a result of that development, the improvement of the properties and machining performance of the coatings.
Plasma-Enhanced Chemical Vapor Deposition of High Quality Cubic BN Films with an Intermediate Layer of Turbostratic BN Thinner than 3 nm
Authors: Yang Hangsheng , Iwamoto Chihiro , Yoshida Toyonobu 
Published: April 2011

ABSTRACTCubic boron nitride (cBN) thin films were deposited on silicon wafers by low-pressure inductively coupled plasma-enhanced chemical vapor deposition (ICP-CVD). By using special substrate pre-treatment processes including positive biasing treatment in H2 plasma or 1200 K pre-heating in H2 atmosphere followed by an N2 plasma treatment, turbostratic BN (tBN) intermediate layer was revealed to directly grow on Si substrates without an initial amorphous layer. The thickness of the tBN transition layer can be reduced to less than 3 nm.
Properties of Molybdenum Nitride Thin Film Deposited by Reactive Sputter Deposition
Authors: Wang Yimin , Seok Jin W. , Lin Ray Y. 
Published: April 2011

ABSTRACTMolybdenum nitride thin film was deposited on silicon wafer with the reactive sputter deposition. γ-Mo2N thin film was obtained with nitrogen content in sputtering gas varying from 10% to 30%. An amorphous structure was observed in the thin film deposited at 50% nitrogen. Crystallinity of Mo-N thin film decreased as the total sputtering gas pressure increased. SEM examinations showed that the surface morphology of Mo-N thin films varies with the nitrogen content in the sputtering gas. The sheet resistivity of as deposited thin film increases with increasing nitrogen content in sputtering gas. The amorphous thin film deposited at 50% nitrogen survived 700°C/5min thermal annealing without obvious crystallization but failed after 800°C/5min thermal annealing, in which the crystalline γ-Mo2N and h-MoSi2 phases were observed. Sheet resistivity measurement showed a decrease in thin film resistivity with increasing thermal annealing temperatures.
Kinetic and Surface Mechanisms to Growth of Hexagonal Boron Nitride
Authors: Barreto Patrícia R. R. , Kull Alan E. , Cappelli Mark A. 
Published: April 2011

ABSTRACTA mechanism is presented for the gas-phase chemistry and surface reactions describing the growth of boron nitride films. The gas phase mechanism includes 33 species and 216 elementary reactions. Rate parameters for 117 elementary reactions were obtained from published experimental/theoretical data and those for the other 99 were determined using transition state theory. The mechanism examined here is an extension and update of a previous mechanism that contained 26 species and 67 elementary reactions. Standard reaction flux/pathway and gradient sensitivity analysis techniques are used to identify important reaction pathways. The calculations were handled through the use of the ChemKin software package. The model was applied to the growth of hexagonal boron nitride in an arcjet plasma source operating on mixture of BF3, H2 and N2. From the growth rate and experimental conditions for such reactors, this work demonstrates that species with mole fractions in the range of 1 × 10-10 − 2 × 10-4 (easily generated by gas-phase conditions) can account for the measured growth rate. A comparison of the predicted mole fractions of the gas-phase species present for the experimental residence times with those required to account for the measured film growth rates allows us to identify possible growth precursors. At the experimental settings, it is found that the residence time of the reacting species does not allow the flow to reach the chemical equilibrium, and that many radicals other than the source gases can account for the measured BN growth rate. The gas-phase is shown to be removed from thermodynamic equilibrium. For comparison, the equilibrium mole fractions were also calculated using an available equilibrium chemistry solver, STANJAN. Growth rates of 10-9 to 10-6 kg m-1 s-1 were measured for a wide range of H2, BF3 and NF3 flux. Both the finite-rate kinetics and equilibrium calculations confirm the importance of added hydrogen to facilitate boron nitride condensation from the gas phase. A simple surface mechanism with 7 steps is proposed with rate constants chosen to best fit the experimental growth kinetics. The results of the model, with surface rate coefficients determined from analogous gas-phase reactions, tuned slightly to agree with the experimental growth rates for BFx, x = 1, 2 or 3, as the rate-limiting growth precursor. It is also shown that the hydrogen atom has a great influence in the growth rate and that fluorine atom etches the hBN films.
Using of SILD technology for surface modification of SnO2 films for gas sensor applications
Authors: Korotcenkov G. , Macsanov V. , Boris Y. , Brinzari V. , Tolstoy V. , Schwank J. , Morante J. 
Published: April 2011

ABSTRACTThe possibilities of SILD (successive ionic layer deposition) technology for modification of surface properties of nano-scaled SnO2 films for gas sensor applications were studied and are discussed in this article. Samples of SnO2 with thickness ranging from 30–40 nm were deposited by spray pyrolysis from SnCl4-water solutions. Nano-clusters of Pd and Ag, deposited by the SILD method were applied for surface modification. PdCl2 and AgNO3 were used as precursors for Pd and Ag deposition on the SnO2 surface.It was found that the method of surface modification by SILD can be used for improving both the sensitivity and the rate of gas response of SnO2-based gas sensors to CO and H2. At the same time, the presence of Pd and Ag clusters on the surface of SnO2 depresses the gas response to ozone.
Thermal and Mass Balance in Reactive Thermal Processing of Nickel Aluminide Coatings on Steel Substrates
Authors: Alaeddine Tarek , Ranganathan Rajesh , Ando Teiichi , Doumanidis Charalabos C. , Wong Peter Y. 
Published: April 2011

ABSTRACTNickel aluminide coatings were produced on steel substrates by reactive thermal processing of pre-plated precursor layers of nickel and aluminum using plasma arc as the heat source. Controlled rapid heating melted the outer aluminum layer, which then dissolved nickel to facilitate the nucleation and growth of a nickel aluminide. The resultant coating microstructures varied from a duplex or triplex structure, consisting of either NiAl3and a eutectic; Ni2Al3, NiAl3and a eutectic; to a fully monolithic Ni2Al3structure, with the latter resulting at high heat input rates and/or low heat-source traverse rates. The temperature of the reaction layer was simulated for the experimental conditions by a numerical model based on Green's function analysis. The nickel concentration at the liquid-solid interface just before any nickel aluminide nucleation was calculated by assuming local equilibrium interface conditions between the liquid layer and the fcc nickel-rich solution. The depth of nickel dissolution, which consequently determines the extent of nickel aluminide growth, was also predicted by the model. Numerical results of the nickel dissolution compared well with experimental observations.
Nanostructured DLC-Ag Composites for Biomedical Applications
Authors: Narayan R. J. , Wang H. , Tiwari A. 
Published: April 2011

ABSTRACTWe have synthesized novel diamondlike carbon coatings with silver nanoparticles embedded into the DLC film. The size of silver nanoparticles that are confined into layered structures has been varied from 5 nm to 50 nm using an ingenious pulsed laser deposition technique. The size of nanoparticles was found to be remarkably uniform within 15%. We have characterized these samples using high-resolution cross-section TEM and STEM-Z contrast techniques, electron energy loss spectroscopy (EELS), Raman, nanohardness, adhesion, and biocompatibility measurements. In the STEM-Z, where the contrast is proportional to atomic number2, we have obtained the details of the atomic structure of silver particles. We have correlated the microstructure with hardness and adhesion properties. The EELS was used in conjunction with STEM-Z to obtain sp3/sp2 bonding ratio. This ratio was compared with Raman result to provide an average bulk value. The role of silver nanoparticles is surmised to provide a reservoir of electrons for antimicrobial activity on the surface, as revealed by our biocompatibility tests.
Mechanical properties of pulsed laser-deposited hydroxyapatite thin films for applications in biomedical implants
Authors: Kim Hyunbin , Vohra Yogesh K. , Lacefield William R. , Camata Renato P. 
Published: April 2011

ABSTRACTWe have obtained nanostructured hydroxyapatite thin films on titanium alloy substrates by pulsed laser deposition. Deposition was carried out using a KrF excimer laser (248 nm) with the energy density of 4 – 7 J/cm2 at substrate temperatures in the 550°C - 650°C range. The crystallinity of the coatings was probed by X-ray diffraction. Phase transitions from hydroxyapatite to other calcium phosphate compounds were observed with varying the substrate temperature during the growth process. Scanning electron microscopy revealed thin films made up of partially sintered nanoscale grains. The average size of nanoscale grains increased significantly with film thickness, suggesting a growth mechanism involving the coalescence of nanoscale grains. As the laser energy density increases, the hydroxyapatite crystallites in the coatings are oriented preferentially along the c-axis perpendicular to the substrate. Mechanical properties of the highly c-axis oriented coatings such as hardness and Young's modulus were studied by using nanoindentation technique.