bluuebunny/crossref_metadata_2025 huggingface dataset:
Holistic Discourse Coherence Annotation for Noisy Essay Writing
Authors: Burstein Jill , Tetreault Joel , Chodorow Martin
Published: October 2013

This paper reviews annotation schemes used for labeling discourse coherence in well-formed and noisy (essay) data, and it describes a system that we have developed for automated holistic scoring of essay coherence. We review previous, related work on unsupervised computational approaches to evaluating discourse coherence and focus on a taxonomy of discourse coherence schemes classified by their different goals and types of data. We illustrate how a holistic approach can be successfully used to build systems for noisy essay data, across domains and populations. We discuss the model features related to human scoring guide criteria for essay scoring, and the importance of using model features relevant to these criteria for the purpose of generating meaningful scores and feedback for students and test-takers. To demonstrate the effectiveness of a holistic annotation scheme, we present results of system evaluations.
Focus Triggers and Focus Types from a Corpus Perspective
Authors: Riester Arndt , Baumann Stefan
Published: October 2013

The article discusses several issues relevant for the annotation of written and spoken corpus data with information structure. We discuss ways to identify focus top-down (via questions under discussion) or bottom-up (starting from pitch accents). We introduce a two-dimensional labelling scheme for information status and propose a way to distinguish between contrastive and non-contrastive information. Moreover, we take side in a current debate, claiming that focus is triggered by two sources: newness and elicited alternatives (contrast). This may lead to a high number of semantic-pragmatic foci in a single sentence. In each prosodic phrase there can be one primary focus (marked by a nuclear pitch accent) and several secondary foci (marked by weaker prosodic prominence). Second occurrence focus is one instance of secondary focus.
Representing ozone extremes in European megacities: the importance of resolution in a global chemistry climate model
Authors: Stock Z. S. , Russo M. R. , Pyle J. A.
Published: October 2013

Abstract. The continuing growth of the world's urban population has led to an increasing number of cities with more than 10 million inhabitants. The higher emissions of pollutants, coupled to higher population density, makes predictions of air quality in these megacities of particular importance from both a science and a policy perspective. Global climate models are typically run at coarse resolution to enable both the efficient running of long time integrations, and the ability to run multiple future climate scenarios. However, when considering surface ozone concentrations at the local scale, coarse resolution can lead to inaccuracies arising from the highly non-linear ozone chemistry and the sensitivity of ozone to the distribution of its precursors on smaller scales. In this study, we use UM-UKCA, a global atmospheric chemistry model, coupled to the UK Met Office Unified Model, to investigate the impact of model resolution on tropospheric ozone, ranging from global to local scales. We focus on the model's ability to represent the probability of high ozone concentrations in the summer and low ozone concentrations, associated with polluted megacity environments, in the winter, and how this varies with horizontal resolution. We perform time-slice integrations with two model configurations at typical climate resolution (CR, ~150 km) and at a higher resolution (HR, ~40 km). The CR configuration leads to overestimation of ozone concentrations on both regional and local scales, while it gives broadly similar results to the HR configuration on the global scale. The HR configuration is found to produce a more realistic diurnal cycle of ozone concentrations and to give a better representation of the probability density function of ozone values in urban areas such as the megacities of London and Paris. We discuss the possible causes for the observed difference in model behaviour between CR and HR configurations and estimate the relative contribution of chemical and meteorological factors at the different scales.
Derivation of critical rainfall thresholds for shallow landslides as a tool for debris flow early warning systems
Authors: Papa M. N. , Medina V. , Ciervo F. , Bateman A.
Published: October 2013

Abstract. Real-time assessment of debris-flow hazard is fundamental for developing warning systems that can mitigate risk. A convenient method to assess the possible occurrence of a debris flow is to compare measured and forecasted rainfalls to critical rainfall threshold (CRT) curves. Empirical derivation of the CRT from the analysis of past events' rainfall characteristics is not possible when the database of observed debris flows is poor or when the environment changes with time. For debris flows and mud flows triggered by shallow landslides or debris avalanches, the above limitations may be overcome through the methodology presented. In this work the CRT curves are derived from mathematical and numerical simulations, based on the infinite-slope stability model in which slope instability is governed by the increase in groundwater pressure due to rainfall. The effect of rainfall infiltration on landside occurrence is modelled through a reduced form of the Richards equation. The range of rainfall durations for which the method can be correctly employed is investigated and an equation is derived for the lower limit of the range. A large number of calculations are performed combining different values of rainfall characteristics (intensity and duration of event rainfall and intensity of antecedent rainfall). For each combination of rainfall characteristics, the percentage of the basin that is unstable is computed. The obtained database is opportunely elaborated to derive CRT curves. The methodology is implemented and tested in a small basin of the Amalfi Coast (South Italy). The comparison among the obtained CRT curves and the observed rainfall amounts, in a playback period, gives a good agreement. Simulations are performed with different degree of detail in the soil parameters characterization. The comparison shows that the lack of knowledge about the spatial variability of the parameters may greatly affect the results. This problem is partially mitigated by the use of a Monte Carlo approach.
A hydro-sedimentary modelling system for flash flood propagation and hazard estimation under different agricultural practices
Authors: Kourgialas N. N. , Karatzas G. P.
Published: October 2013

Abstract. A modelling system for the estimation of flash flood flow characteristics and sediment transport is developed in this study. The system comprises of three components: (a) a modelling framework based on the hydrological model HSPF, (b) the hydrodynamic module of the hydraulic model MIKE 11 (quasi-2-D), and (c) the advection-dispersion module of MIKE 11 as a sediment transport model. An important parameter in hydraulic modelling is the Manning's coefficient, an indicator of the channel resistance which is directly depended on riparian vegetation changes. Riparian vegetation effect on flood propagation parameters such as water depth (inundation), discharge, flow velocity, and sediment transport load is investigated in this study. Based on the obtained results, when the weed cutting percentage is increased, the flood wave depth decreases while flow discharge, velocity and sediment transport load increase. The proposed modelling system is used to evaluate and illustrate the flood hazard for different cutting riparian vegetation scenarios. For the estimation of flood hazard, a combination of the flood propagation characteristics of water depth, flow velocity and sediment load was used. Next, an optimal selection of the most appropriate agricultural cutting practices of riparian vegetation was performed. Ultimately, the model results obtained for different agricultural cutting practice scenarios can be employed to create flood protection measures for flood prone areas. The proposed methodology was applied to the downstream part of a small mediterranean river basin in Crete, Greece.
The effect of a high monounsaturated fat diet on body weight, backfat and loin muscle growth in high and medium-lean pig genotypes
Authors: Mas G. , Soler J. , Llavall M. , Tibau J. , Roca R. , Coll D. , Fàbrega E.
Published: October 2013

The objective of this study was to evaluate whether the use of a diet rich in oleic acid could have an effect on daily weight gain, backfat and loin muscle (Longissimus thoracis) depth. One hundred and ninety-two barrows and gilts, from two genotypes were fed a grain and soy diet (CONTROL with 28% C18:1) or a similar diet enriched with oleic acid (HO with 43% C18:1, Greedy-Grass OLIVA®). The pigs were housed in 16 pens in groups of 12 according to their sex, diet and genotype. From 75 days of age every three weeks, the pigs were weighed and the backfat and loin muscle depth were ultrasonically recorded (PIGLOG®). The inclusion of the dietary fat had no significant effect on the growth variables nor on the backfat and loin muscle depth measurements taken. However, the barrows resulted in higher live weight and backfat compared to the gilts at the end of the trial. Conversely, the gilts showed higher loin depth. Moreover, York-sired pigs were heavier than Pietrain-sired pigs during the whole trial and showed higher backfat at the last two measurements. Pietrain-sired pigs had higher loin muscle depth at the last measurements. The results of the present study suggest that the addition of a dietary fat into diets aiming at modifying the meat fatty acid profile has no detrimental effects on performance variables, or on backfat and loin muscle growth and thus, no negative economic impact for producers.
Media Clips: The Psychology of Discounting: Something Doesn't Add Up//Math-hattan
Authors: Lavallee Adam , Armitage Stephen E. J.
Published: October 2013

Students analyze media items to answer related mathematical questions. This month's clips feature a percentage discount and a walking tour of Manhattan, which leads to probability and geometry questions.
Stainless Steel: How Problems Arise and How to Avoid Them
Authors: Mackey Erin , Seacord Tom , Lamb Stephen
Published: October 2013

Stainless steel ‐ widely used in drinking water, wastewater, and water reuse systems ‐ can fail from corrosion. Careful attention should be paid to specification, handling, and installation of stainless steel piping and components.
Granular Data Enhance Customer Service
Authors: Fiut Brian
Published: October 2013

Resolving high‐bill complaints, conducting comparative analyses, and spotting potential theft or fraud are just a few ways advanced metering infrastructure data can improve customer service.
Water Cart Supplies Downtown Events
Authors: Woodford Brad
Published: October 2013

The Water Cart is an apparatus that provides access to water for downtown events and festivals in Lee's Summit, MO. It also meters the water and ensures proper backflow protection is in place.
Stochastic homeostasis in human airway epithelium is achieved by neutral competition of basal cell progenitors
Authors: Teixeira Vitor H , Nadarajan Parthiban , Graham Trevor A , Pipinikas Christodoulos P , Brown James M , Falzon Mary , Nye Emma , Poulsom Richard , Lawrence David , Wright Nicholas A , McDonald Stuart , Giangreco Adam , Simons Benjamin D , Janes Sam M
Published: October 2013

Lineage tracing approaches have provided new insights into the cellular mechanisms that support tissue homeostasis in mice. However, the relevance of these discoveries to human epithelial homeostasis and its alterations in disease is unknown. By developing a novel quantitative approach for the analysis of somatic mitochondrial mutations that are accumulated over time, we demonstrate that the human upper airway epithelium is maintained by an equipotent basal progenitor cell population, in which the chance loss of cells due to lineage commitment is perfectly compensated by the duplication of neighbours, leading to “neutral drift” of the clone population. Further, we show that this process is accelerated in the airways of smokers, leading to intensified clonal consolidation and providing a background for tumorigenesis. This study provides a benchmark to show how somatic mutations provide quantitative information on homeostatic growth in human tissues, and a platform to explore factors leading to dysregulation and disease.
Abruptness Improvement of the Interfaces of AlGaN/GaN Superlattices by Cancelling Asymmetric Diffusion
Authors: Cai Duanjun , Chen Xiaohong , Xu Hongmei , Lin Na , Xu Fuchun , Chen Hangyang
Published: October 2013

Interfacial abruptness plays a critical role in affecting the quantum confinement effect in heterostructures. Here, we accurately determine the inter-diffusion depth across the AlGaN/GaN interfaces and propose a simple blocking scheme to effectively improve the superlattice abruptness. It is found that the Al diffusion depth at the upper and lower interfaces of the AlGaN barrier appears considerably asymmetric. Such difference leads to the gradient interfacial region and the asymmetric quantum well shape. A pair of ultra-thin blocking layers is introduced to the GaN/AlGaN interface to block the Al downward diffusion. After the blocking treatment, the interfacial abruptness is improved and the light emission intensity from the superlattice can be effectively enhanced.
GaN-Based Metal–Insulator–Semiconductor Ultraviolet Photodetectors with HfO2Insulators
Authors: Chen Chin-Hsiang
Published: October 2013

Nitride-based metal–insulator–semiconductor (MIS) ultraviolet (UV) photodetectors (PDs) with a hafnium oxide (HfO2) insulating layer was fabricated for the first time and characterized successfully. It was found that we can achieve a small dark current and a large photocurrent to dark current contrast ratio using the proposed device with the HfO2insulating layer. Furthermore, the noise equivalent power was substantially reduced, and detectivity was increased using HfO2insulators.
Exploring Electro-active Functionality of Transparent Oxide Materials
Authors: Hosono Hideo
Published: October 2013

Ceramics, one of the earliest materials used by humans, have been used since the Stone Age and are also one of the core materials supporting modern society. In this article, I will review the features of transparent oxides, the main components of ceramics, and the progress of research on their electro-active functionalities from the viewpoint of material design. Specifically, the emergence of the functionality of the cement component 12CaO·7Al2O3, the application of transparent oxide semiconductors to thin-film transistors for flat panel displays, and the design of wide-gap p-type semiconductors are introduced along with the progress in their research. In addition, oxide semiconductors are comprehensively discussed on the basis of the band lineup.
Piezoelectricity in PbZrxTi1-xO3 Studied by Density-Functional Perturbation Theory Supercell Calculations
Authors: Kim SeongMin , Lee Woo-Jin , Cho Yong-Hee , Shim Munbo , Kim Sungjin
Published: October 2013

First-principles calculations of the piezoresponses (e
33) of PbZr
x
Ti1-x
O3 (PZT) with various crystalline phases and Zr/Ti ratios (composition: B-site cations) are performed at room temperature using density-functional perturbation theory (DFPT) to understand the experimental observation that large piezoresponses occur at the morphotropic phase boundary (MPB). The results of ab initio calculations indicate that PZT (Zr/Ti = 52/48) with a tetragonal (P4MM) phase shows the lowest formation energy (stable) and the highest piezoelectric coefficient, e
33, in the MPB region. The Z
*/Δε ratio (where Z
* is the Born effective charge and Δε is the variation in the internal strain) is computed, and we find that laterally bonded oxygen atoms are the main contributors to e
33 in the above structure owing to the low Δε3 caused by perturbation.
Investigation of Dark-Count-Less Lu2(SiO4)O-Multipixel-Photon Detector and Its Application to Photon Counting X-ray Computed Tomography Using Iodine Media
Authors: Sato Eiichi , Oda Yasuyuki , Kodama Hajime , Hagiwara Osahiko , Matsukiyo Hiroshi , Osawa Akihiro , Enomoto Toshiyuki , Watanabe Manabu , Kusachi Shinya , Sato Shigehiro , Ogawa Akira
Published: October 2013

X-ray photons are detected using a Lu2(SiO4)O [LSO] single-crystal scintillator with a decay time of 40 ns and a multipixel photon counter (MPPC). The photocurrent from the MPPC is amplified by a high-speed current–voltage amplifier with an 80 MHz-gain-band operational amplifier, and the 200-ns-width event pulses are sent to a multichannel analyzer (MCA) to measure X-ray spectra. The MPPC was driven in the pre-Geiger mode at a bias voltage of 70.7 V and a temperature of 23 °C. Photon-counting computed tomography (PC-CT) is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by linear scanning at a tube current of 1.5 mA. In PC-CT, the event pulse height is dispersed using a 7-ns-delay comparator. The exposure time for obtaining a tomogram is 10 min with scan steps of 0.5 mm and rotation steps of 1.0°. At a tube voltage of 80 kV, the maximum count rate is 250 kcps. We carry out PC-CT using iodine media and confirm the energy-dispersive effect with changes in the lower level voltage of event pulses using a comparator.
Study of Novel Floating-Gate Oxide Semiconductor Memory Using Indium–Gallium–Zinc Oxide for Low-Power System-on-Panel Applications
Authors: Yamauchi Yoshimitsu , Kamakura Yoshinari , Isagi Yousuke , Matsuoka Toshimasa , Malotaux Satoshi
Published: October 2013

A novel floating-gate oxide semiconductor (FLOTOS) memory using a wide-band-gap indium–gallium–zinc oxide (IGZO) is presented for low-power system-on-panel applications. An IGZO thin-film-transistor (TFT) is used as a memory transistor for controlling read current as well as a switching transistor for storing charges in a storage capacitor (C
s). The FLOTOS memory is fabricated using a standard IGZO TFT process without any additional process or mask steps. The proposed precharge-assisted threshold voltage compensation technique makes it possible to realize an infinite number of write cycles and a low-power write operation with a bit-line voltage of 5 V. Furthermore, excellent data retention longer than 10 h is obtained at 60 °C even under the worst bias-stress condition of read operation with the ultra low off-state leakage (2.8×10-20 A/µm) of the IGZO TFTs, which is estimated to be smaller by more than 7 orders of magnitude than that of polycrystalline silicon TFTs.
Characterization of Ge Films on Si(001) Substrates Grown by Nanocontact Epitaxy
Authors: Ikeda Wataru , Nakamura Yoshiaki , Okamoto Shogo , Takeuchi Shotaro , Kikkawa Jun , Ichikawa Masakazu , Sakai Akira
Published: October 2013

We quantitatively characterized Ge films epitaxially grown on Si(001) substrates by nanocontact epitaxy. The naocontact epitaxy was composed of three stages: elastically-strain-relaxed nanodot (ND) formation, second layer growth for surface flattening, and final layer growth for high crystallinity. X-ray diffraction results showed that the lattice mismatch strain was almost-fully relaxed on the order of ∼0.05% in Ge films as thin as 100 nm, and was independent of the growth condition of films (second and final layers) above NDs. This supports the idea of a mechanism in which strain relaxation is caused by elastically-strain-relaxed ND formation. It was also verified by simple elastic theory calculation and plan-view transmission electron microscopy. Photoluminescence was observed from the thin film at ∼0.8 eV, suggesting high quality with less point defects.
Analysis of Channel Stress Induced by NiPt-Silicide in Metal–Oxide–Semiconductor Field-Effect Transistor and Its Generation Mechanism
Authors: Mizuo Mariko , Yamaguchi Tadashi , Kudo Shuichi , Hirose Yukinori , Kimura Hiroshi , Tsuchimoto Jun-ichi , Hattori Nobuyoshi
Published: October 2013

Channel stress induced by NiPt-silicide films in metal–oxide–semiconductor field-effect transistors (MOSFETs) was demonstrated using UV-Raman spectroscopy, and its generation mechanism was revealed. It was possible to accurately measure the channel stress with the Raman test structure. The channel stress depends on the source/drain doping type and the second silicide annealing method. In order to discuss the channel stress generation mechanism, NiPt-silicide microstructure analyses were performed using X-ray diffraction analysis and scanning transmission electron microscopy. The channel stress generation mechanism can be elucidated by the following two factors: the change in the NiSi lattice spacing, which depends on the annealing temperature, and the NiSi crystal orientation. The analyses of these factors are important for controlling channel stress in stress engineering for high-performance transistors.
Wet Etching of Amorphous TiO2 Thin Films Using H3PO4–H2O2 Aqueous Solution
Authors: Okazaki Sohei , Ohhashi Takuya , Nakao Shoichiro , Hirose Yasushi , Hitosugi Taro , Hasegawa Tetsuya
Published: October 2013

We report on the wet etching of amorphous undoped and Nb-doped TiO2 thin films using H3PO4–H2O2 etching solution. The etching rate (R) showed a maximum at a H3PO4 concentration of approximately 50 wt % at 80 °C, suggesting that H2PO4
- and/or H3O+ is responsible for the etching reaction. The addition of H2O2 to H3PO4 solution significantly enhanced R, and an optimized solution exhibited an R of 13 nm/min at 80 °C, which is one order of magnitude higher than that using H2SO4. These results demonstrate that H3PO4–H2O2 aqueous solution is an effective etchant for TiO2-based amorphous thin films.
Effects of Oxide Seeding Layers on Electrical Properties of Chemical Solution Deposition-Derived Pb(Mg1/3Nb2/3)O3–PbTiO3 Relaxor Thin Films
Authors: Arai Takashi , Goto Yasuyuki , Yanagida Hiroshi , Sakamoto Naonori , Ohno Tomoya , Matsuda Takeshi , Wakiya Naoki , Suzuki Hisao
Published: October 2013

Relaxor ferroelectrics Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) have attracted considerable attention because of their excellent electrical properties, such as high dielectricity and piezoelectricity, for application to super capacitors, piezoelectric actuators, and so on. It is well known that the electrical properties of ferroelectric thin films depend on several parameters, such as crystal orientation, composition, and residual stress. In this study, the effects of the lead titanate and lanthanum nickel oxide seeding layers on the film orientation, electrical properties, and low-temperature crystallization behavior were investigated for Chemical Solution Deposition (CSD)-derived PMN–PT thin films. As a result, PMN–PT thin films with (001)C- and (111)C-preferred orientations were successfully obtained by designing the seeding layers. Both thin films exhibited very good ferroelectricity because of their good crystallinity and preferred orientation.
Bi4Ti3O12 Nanowall Growth Driven by Anisotropic Growth Rate and Size Control
Authors: Yamada Tomoaki , Shibata Takaaki , Ishii Koji , Kimura Junichi , Funakubo Hiroshi , Yoshino Masahito , Nagasaki Takanori
Published: October 2013

Ferroelectric and piezoelectric Bi4Ti3O12 was epitaxially grown on TiO2(101) with a(b)-axis orientation by pulsed laser deposition (PLD). Owing to the strong growth anisotropy indigenous to bismuth-layered perovskites including Bi4Ti3O12, it grew rapidly along the a- and b-axes and slowly along the c-axis. Therefore, at low deposition temperatures below 700 °C, Bi4Ti3O12 nuclei did not merge with each other along the c-axis during the growth, which resulted in the formation of the nanowall-like structure. It was found that the width of nanowalls decreased with decreasing deposition temperature, which implies that the surface diffusivity of PLD species plays a role in changing the width of nanowalls. It was also found that the interval of nanowalls can be effectively controlled by adjusting the oxygen pressure during the deposition.
Strain-Stable Nonlinear Dielectric Responses in Pyrochlore Bismuth Zinc Niobate Thin Films
Authors: Nakajima Mitsumasa , Yamada Tomoaki , Okaura Shingo , Funakubo Hiroshi
Published: October 2013

The effect of film strain on the dielectric responses of pyrochlore Bi–Zn–Nb–O (BZN) thin films was investigated in (111)-oriented BZN thin films grown on various substrates. The bias-field dependence of dielectric constant revealed that both the linear and nonlinear electric susceptibilities of BZN thin films are stable against the film strain, unlike conventional tunable materials, such as (Ba,Sr)TiO3. The difference in dielectric nonlinearity between BZN and BST films is discussed on the basis of the phenomenological theory. The strain stability of linear and nonlinear dielectric responses of BZN is available for practical thin-film tunable applications.
Density Functional Theory Study on How Electron Spin Configuration of Co3+ Ion Affects the Structure and Magnetism of Co-Doped Bismuth Ferrite
Authors: Ricinschi Dan
Published: October 2013

In this paper, we use first-principles calculations carried out under the density functional theory for probing ways to enhance the magnetization of materials from BiFeO3 (BFO) family while preserving robust ferroelectricity. In addition to analyzing ferrimagnetic arrangements of B-site magnetic ions with different magnetic moments (Fe3+ and Co3+) in BFO-based supercells, we have also studied the impact of various electronic configurations (high-spin, low-spin, intermediate-spin) of Co3+ ion on crystal structure, ferroelectricity and magnetism of such systems. Our results suggest that tetragonal Co-doped BFO (BFCO) compounds with low-spin and intermediate-spin electronic configuration of Co have robust coupling between the spontaneous polarization and magnetic degrees of freedom. Furthermore, we have found an additional route to enhance the magnetization of tetragonal BFCO compounds with Co3+ in intermediate spin state, while remaining coupled to ferroelectric degrees of freedom, namely by inducing a ferrimagnetic-to-ferromagnetic phase transition.
Observation of 57Fe-Enriched BiFeO3 Thin Films Using Mössbauer Spectroscopic Microscope
Authors: Tanaka Kiyotaka , Tsukamoto Yoshinori , Okamura Soichiro , Yoshida Yutaka
Published: October 2013

57Fe-enriched BiFeO3 (BFO) thin films were produced from a stoichiometric precursor solution by chemical solution deposition process. The perovskite BFO thin film fabricated at 550 °C on a Pt/Ti/SiO2/Si substrate showed saturated polarization–electric field (P–E) hysteresis loops. The remanent polarization P
r and the coercive field E
c at room temperature were 89 µC/cm2 and 365 kV/cm, respectively. The Mössbauer spectra consisted of the antiferromagnetic perovskite BFO and a paramagnetic component at a fraction in the range of 11 to 14%. The secondary component was supposed to be due to Bi2Fe4O9 and/or an amorphous component, influencing the ferroelectric property at room temperature. The Bi2Fe4O9 thin film was also fabricated at 700 °C on a SiO2/Si substrate. Furthermore, we tried to measure the mapping images corresponding to the perovskite BFO and Bi2Fe4O9 components separately using a Mössbauer spectroscopic microscope. A mapping image showed the distribution of the perovskite BFO component on the film.
Phase Transition Behaviors in [011]-Oriented Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 Single Crystals Studied by Dielectric and Micro-Brillouin Spectroscopies
Authors: Kim Tae Hyun , Ko Jae-Hyeon , Kojima Seiji
Published: October 2013

Phase transition behaviors of unpoled and [011]-poled relaxor ferroelectric Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystals were investigated over a wide temperature range by dielectric and Brillouin scattering spectroscopies. The [011]-poled crystal exhibited two discontinuous dielectric and acoustic anomalies at ∼119 and ∼126 °C, which were attributed to two poling-induced structural phase transitions from rhombohedral to orthorhombic, and then to tetragonal symmetry. However, this poled crystal maintained the diffused phase transition behaviors of the unpoled one at higher temperatures above ∼126 °C. The disappearance of the poling effect upon the diffuse phase transition near the T
C suggests that the macroscopic ferroelectric domains formed by poling are decomposed into mesoscopic and nano size polar regions at ∼126 °C. These polarization fluctuations and the coupling of these dynamic polar regions to the acoustic waves play the dominant role in the dielectric and acoustic anomalies, respectively. Therefore, a diffusive nature was commonly observed in both unpoled and poled single crystals near T
C.
Growth of (1-x)NaNbO3–xBaTiO3 Single Crystals by Slow-Cooling and Flux Methods
Authors: Watanabe Takayuki , Yabuta Hisato , Ueda Miki , Watanabe Masatoshi , Suzuki Tatsuya , Miura Kaoru , Ito Naoko , Kumada Nobuhiro
Published: October 2013

(1-x)NaNbO3–xBaTiO3 single crystals were grown by slow-cooling and flux methods. In the slow-cooling method, 0.88NaNbO3–0.12BaTiO3 powder was melted in a platinum crucible at 1500 °C and cooled down to 1000 °C. Slow cooling at less than 21 °C/h led to a bulky single crystal, and the BaTiO3/NaNbO3 ratio was graded inside the single crystal as expected from the phase diagram. Further slow cooling at 5 °C/h with the aim of improving the compositional uniformity increased the level of contamination of platinum in the single crystals from the crucible. Cuboidal single crystals with a (100) facet were grown in Na2B4O7 flux through a cooling process from 1200 to 1000 °C at 1 °C/h. There was no compositional gradient inside the cuboidal crystals, and the BaTiO3 content of the single crystals remained within 2–3% irrespective of the raw powder/flux ratio and the BaTiO3 composition in the raw powder. The obtained single crystals were orthorhombic ferroelectrics with a phase transition temperature of 310–330 °C.
Temperature Dependence of Photoelastic Effect in KTa1-xNbxO3 Crystals and Investigation of Its Origin
Authors: Miyazu Jun , Kawamura Sohan , Imai Tadayuki , Kobayashi Junya
Published: October 2013

The temperature dependence of the photoelastic effect in KTa1-x
Nb
x
O3 crystals was evaluated by measuring the elastic stiffness coefficient c
11 and the change in the refractive index with stress. The elastic stiffness coefficient c
11 was measured by using an ultrasonic thickness gauge and the change in the refractive index with the stress was measured by using a Mach–Zehnder interferometer. By considering the effect of the increased departure from the Curie–Weiss law with stress, we succeeded in obtaining a theoretical fit with the measured temperature dependence of the photoelastic effect. The temperature dependence of the photoelastic constant was described by combining the effects of the thermal fluctuation of the ionic and electronic polarizations and the effect of the local polarization.
Grain Size Effect on Dielectric Properties of Ba0.92Ca0.08TiO3 Ceramics
Authors: Hoshina Takuya , Furuta Tsutomu , Yamazaki Takahiro , Takeda Hiroaki , Tsurumi Takaaki
Published: October 2013

We demonstrated the grain size effect on the dielectric properties of Ba0.92Ca0.08TiO3 ceramics. Fine-grained Ba0.92Ca0.08TiO3 ceramics with micrometer- and nanometer-sized grains were fabricated by the two-step sintering method and aerosol deposition method, respectively. The permittivity of Ba0.92Ca0.08TiO3 ceramics increased with decreasing grain size when the grain size was more than 400 nm, whereas it decreased when the grain size was below 400 nm. The permittivity of Ba0.92Ca0.08TiO3 ceramics with micrometer-sized grains was lower than that of BaTiO3 ceramics. This was caused by the hardening of the soft mode and the decrease in the 90° domain-wall contribution by Ca substitution. Moreover, the grain size that gave the maximum permittivity for Ba0.92Ca0.08TiO3 ceramics was lower than that for BaTiO3 ceramics. This result suggested that the Ba0.92Ca0.08TiO3 was less sensitive to the grain size effect than BaTiO3 ceramics. These features in the grain size dependence of permittivity were explained by the tetragonal structure stability of Ba0.92Ca0.08TiO3.
Crystal Structural Analyses of Ferrielectric Tetragonal (Bi1/2Na1/2)TiO3–7%BaTiO3 Powders and Single Crystals
Authors: Kitanaka Yuuki , Ogino Motohiro , Hirano Kiyotaka , Noguchi Yuji , Miyayama Masaru , Kagawa Yutaka , Moriyoshi Chikako , Kuroiwa Yoshihiro , Torii Shuki , Kamiyama Takeshi
Published: October 2013

We have investigated the crystal structure of (Bi1/2Na1/2)TiO3–7%BaTiO3 (BNT–7%BT) by high-resolution neutron powder diffraction (NPD) and high-energy synchrotron radiation X-ray diffraction (SR-XRD) analyses. The NPD study revealed that the BNT–7%BT crystals have a single-phase tetragonal structure with P4b
m symmetry. The crystal structure refined by the Rietveld method was found to be similar to the ferrielectric P4b
m phase reported for BNT at a high temperature of 673 K. The SR-XRD analyses for single crystals of BNT–7%BT demonstrated that the P4b
m phase remains as a stable phase in the crystals even after a high electric field is applied for poling, which is different from the structural analysis of ceramics by Ma et al. [Phys. Rev. Lett. 109 (2012) 107602].
Effect of Oxygen Pressure on Electrical Properties of BiFe0.9Co0.1O3 Thin Films Prepared by Pulsed Laser Deposition
Authors: Hojo Hajime , Onuma Ko , Ikuhara Yuichi , Azuma Masaki
Published: October 2013

The crystal structures and electrical properties of epitaxial BiFe0.9Co0.1O3 thin films grown by pulsed laser deposition on SrRuO3/SrTiO3(001) substrates under different oxygen pressures were investigated. The unit cell volume of BiFe0.9Co0.1O3 thin films monotonically decreases with increasing oxygen pressure from 10 to 17 Pa, while the leakage current is minimum at 15 Pa. Oxygen content variation in the BiFe0.9Co0.1O3 thin films is proposed to explain the obtained experimental results. The BiFe0.9Co0.1O3 thin film deposited at 15 Pa shows ferroelectric switching behavior with inversion current at room temperature.
Refined Position of Morphotropic Phase Boundary and Compositional Optimization of Pb(Mn1/3Nb2/3)O3–PbZrO3–PbTiO3 Solid Solutions
Authors: Kobune Masafumi , Okuda Haruka , Nishioka Hiroshi , Kikuchi Takeyuki
Published: October 2013

The morphotropic phase boundary (MPB) for high-density solid solutions with compositions of xPb(Mn1/3Nb2/3)O3–yPbZrO3–zPbTiO3 (PMnNZT) with x = 0.02–0.16, y = 0.42–0.56, and z = 0.42–0.56 has been refined on the basis of an analysis of the dielectric and piezoelectric properties of the fabricated samples. An X-ray diffraction analysis of the PMnNZT solid solutions suggested that the refined rhombohedral-tetragonal MPB in this material system is in the compositional region x = 0.02–0.134, y = 0.42–0.54, and z = 0.44–0.485. It was found that a hard-mode solid solution with x = 0.10, y = 0.45, and z = 0.45, which lies in the refined MPB region, exhibited excellent piezo- and ferroelectric properties highlighting its potential as a high-power piezoelectric material for ultrasonic vibrators and piezoelectric transformers.
Morphotropic Phase Boundary Slope of (K,Na,Li)NbO3–BaZrO3Binary System Adjusted Using Third Component (Bi,Na)TiO3Additive
Authors: Karaki Tomoaki , Katayama Tsunehiro , Yoshida Kazuhiro , Maruyama Subaru , Adachi Masatoshi
Published: October 2013

In the binary composition-temperature phase diagram, the slope of the phase boundary is related to the temperature stability of the phases and/or properties. The slope of the tetragonal–rhombohedral morphotropic phase boundary (MPB) in the BaZrO3–(K,Na,Li)NbO3(BZ–KNLN) binary system has been adjusted using the third component (Bi,Na)TiO3(BNT). Piezoceramics were synthesized by a conventional solid-state reaction method, and their crystal structures as well as their MPB were determined from X-ray diffraction patterns measured from room temperature to 300 °C. With increasing BNT content, the slope of the MPB changed from negative to positive. An MPB with temperature-independent behavior, the so called vertical MPB, was successfully discovered in this lead-free piezoceramic system. The MPB composition was determined to be 0.075BZ–0.915KNLN–0.01BNT and the Curie temperature was found to be about 270 °C. The results obtained in this work could be used to develop high-performance lead-free piezoceramics compatible with lead-based ones. Furthermore, this is the first time a vertical MPB has been artificially formed by adjusting the MPB slope. The research method presented in this work has important practical implications as well as scientific interest for searching for vertical MPBs in lead-free piezoceramic systems.
Effects of Heat Treatment after Poling on Dielectric and Piezoelectric Properties in Li0.06Na0.94NbO3 Ceramics
Authors: Aoyagi Rintaro , Maeda Masaki , Yokota Takeshi , Gomi Manabu
Published: October 2013

The Influence of the heat treatment on the electrical properties in Li0.06Na0.94NbO3 (LNN6) lead-free ceramics was investigated. LNN6 poled samples showed an electromechanical coupling factor, k
p, of 0.19–0.20 and a mechanical quality factor, Q
m, of 800–900. By heat treatment at 320 °C for 10 h, k
p hardly changed, but Q
m markedly increased from 850 to 2890. The increase in Q
m that depended on the heat treatment temperature and a higher Q
m were obtained at 300 and 320 °C, which are near phase transition temperatures. The dielectric loss tan
δ at a low frequency decreased with heat treatment. The poling field dependence of piezoelectric properties showed that the heat-treated samples have higher coercive field and internal bias. These results revealed that the heat treatment affects piezoelectric hardening for LNN6 ceramics.
Lead-Free Piezoelectric MEMS Energy Harvesters of (K,Na)NbO3Thin Films on Stainless Steel Cantilevers
Authors: Tsujiura Yuichi , Suwa Eisaku , Kurokawa Fumiya , Hida Hirotaka , Suenaga Kazufumi , Shibata Kenji , Kanno Isaku
Published: October 2013

We fabricated piezoelectric MEMS energy harvesters (EHs) of lead-free (K,Na)NbO3(KNN) thin films on microfabricated stainless steel cantilevers. The use of metal substrates makes it possible to fabricate thin cantilevers owing to a large fracture toughness compared with Si substrates. KNN films were directly deposited onto Pt-coated stainless steel cantilevers by rf-magnetron sputtering, thereby simplifying the fabrication process of the EHs. From XRD measurement, we confirmed that the KNN films on Pt-coated stainless steel cantilevers had a perovskite structure with a preferential (001) orientation. The transverse piezoelectric coefficiente31fand relative dielectric constant εrwere measured to be -3.8 C/m2and 409, respectively. From the evaluation of the power generation performance of a KNN thin-film EH (length: 7.5 mm, width: 5.0 mm, weight of tip mass: 25 mg), we obtained a large average output power of 1.6 µW under vibration at 393 Hz and 10 m/s2.
Unique Activity-Meter with Piezoelectric Poly(vinylidene difluoride) Films and Self Weight of the Sensor Nodes
Authors: Nogami Hirofumi , Okada Hironao , Takamatsu Seiichi , Kobayashi Takeshi , Maeda Ryutaro , Itoh Toshihiro
Published: October 2013

We have developed piezoelectric switches for application in ultra low-power wireless sensor nodes to monitor the health condition of chickens. Using Pb(Zr0.52,Ti0.48)O3(PZT) thin films, we have developed S-shaped PZT cantilevers with proof masses. Since the resonant frequency of PZT devices is approximately 24 Hz, we have utilized their superharmonic resonance to detect chicken movements with frequencies as low as 5–15 Hz. By attaching sensor nodes to chickens, we successfully measured the activity of chickens. However, the PZT devices of other sensor nodes broke down. S-shaped PZT devices are adequate for low vibrations, but are beset by the structural problems of fragmentation upon impact. To address these problems, we examine a method of utilizing poly(vinylidene difluoride) (PVDF) films, which are tough and generate high piezoelectric output voltages under a large stress, as piezoelectric switches. We suggest that the self-weight of sensor nodes be used as the mass of the cantilevers of the PVDF films. One end of a PVDF film is fixed to the case of a sensor node, and the other end is attached to the sensor node. Since PVDF films are subjected to force generated by the self-weight of sensor nodes, high output voltages are expected. A result of measuring output voltages, we confirm the output voltages to be approximately the same as those of PZT devices below 15 Hz at 0.5 m/s2vibration, which is close to chicken movements. Thus, we consider that we have successfully fabricated a tough wireless sensor node for chickens, utilizing the features of PVDF films.
Fundamental Study on Vibration in Edge Face of Piezoelectric Chiral Polymer Film
Authors: Takarada Jun , Kataoka Takuya , Yamamoto Ken , Nakiri Takuo , Kato Atsuko , Yoshida Tetsuo , Tajitsu Yoshiro
Published: October 2013

We evaluate the vibration in the edge face of a poly(L-lactic acid) (PLLA) film from the propagated signal of an ultrasonic wave generated by the excitation force of the edge. Although the excitation area is too small to drive the edge face, the vibration can be measured only using the fixing method that does not suppress the resonance and the equipment with a high signal-to-noise ratio. This is considered to be due to the fact that the theoretically calculated force of the PLLA film is more than 10 times larger than that of a well-known ferroelectric polymer film, poly(vinylidene fluoride). We confirm that the film functions as a resonator and can be applied to a resonated transducer. In spite of the vibration in the edge face of the polymer film, we observe compliant responses to excitations by burst or rectangular waves. The practicality of a resonator can be suggested.
Electronic Polarization in KNbO3Visualized by Synchrotron Radiation Powder Diffraction
Authors: Kawamura Shoto , Magome Eisuke , Moriyoshi Chikako , Kuroiwa Yoshihiro , Taniguchi Nao , Tanaka Hiroshi , Maki Sachiko , Takata Masaki , Wada Satoshi
Published: October 2013

Electron charge density studies of a potassium niobate KNbO3perovskite-type crystal have been carried out by analyzing synchrotron radiation X-ray powder diffraction data using a combination of the Rietveld method and the maximum entropy method. The crystal structures of the cubic, tetragonal, orthorhombic, and rhombohedral phases are accurately analyzed associated with the successive ferroelectric phase transitions by taking the multicomponent structures in the ferroelectric phases into account. The electrostatic potential analyses reveal the emergence of electronic polarization arising from the anisotropic covalent bonding on the Nb and O atoms, while no significant electronic polarization is detected on the isolated K ion. Thus, the spontaneous polarization is caused by the ionic displacements of the constituent atoms and the imbalance of the hybrid atomic orbitals on the Nb–O bonding.
Simultaneous Multi-Bit Recording in Fused Silica for Permanent Storage
Authors: Shiozawa Manabu , Watanabe Takao , Tatsu Eriko , Umeda Mariko , Mine Toshiyuki , Shimotsuma Yasuhiko , Sakakura Masaaki , Nakabayashi Miki , Miura Kiyotaka , Watanabe Koichi
Published: October 2013

In recent years, optical discs and hard disc drives have been widely used as storage media. However, the lifetime of recorded data in these media is about 100 years. On the other hand, a permanent storage system that can store data for more than 1,000 years is strongly required, especially for historically valuable data. One candidate system for permanent storage is a system using fused silica, which is thermally and chemically stable. In this paper, we reported simultaneous multi-bit recording in fused silica with a femtosecond laser and a spatial light modulator. The recording quality was evaluated using signal-to-noise ratio with an optical microscope. We recorded a four-layer sample with a dot pitch of 2.8 µm and obtained a signal-to-noise ratio greater than 15 dB. Furthermore, we confirmed that the sample had good thermal resistance at 1,000 °C for 120 min, which indicates a lifetime of over 319 million years.
A Driveless Read System for Permanently Recorded Data in Fused Silica
Authors: Watanabe Takao , Shiozawa Manabu , Tatsu Eriko , Kimura Shigeharu , Umeda Mariko , Mine Toshiyuki , Shimotsuma Yasuhiko , Sakakura Masaaki , Nakabayashi Miki , Miura Kiyotaka , Watanabe Koichi
Published: October 2013

A driveless, multilayer read system was demonstrated as applicable to a permanent digital-storage using fused silica. The combination of a low-magnification microscope and signal processing were simple enough to be emulated in the distant future. Test data were recorded in a 2-mm-thick fused-silica plate by a femtosecond laser to form four layers with dot pitch of 2.8 µm and interlayer distance of 60 µm. The total recording density was 40 Mbytes/in.2, which is as high as that of a conventional compact disc. This system achieved a bit-error rate in the order of 10-3 when reading the test data (without error-correction code) from images taken at a 19.5-times-magnification. Signal processing using unsharp masking and subtraction of images at different focal points effectively contribute to read data from blurred image with the low bit-error rate.
Scatterometry of Slant Incidence to Isolated Scatterers for High-Density Memory
Authors: Hoshino Tetsuya , Yatagai Toyohiko , Itoh Masahide
Published: October 2013

The turning on and off of a convex scatterer can be used to store information in digital versatile disc (DVD) or Blu-ray technology. In addition, the distance between scatterers can be used as information, if it is precisely measured. Using a recently developed method, a single Fourier transformation of a diffraction pattern can be used to measure the distance between scatterers with high precision and without a lens. To enhance the precision for high-density memory, we examined a method to improve the resolution of measuring isolated convexes. We show by simulation of RCWA that slant incident light is useful for this purpose. We also show by experiment the validity of the method using gratings and the wing of a butterfly.
1 Tbit/inch2 Recording in Angular-Multiplexing Holographic Memory with Constant Signal-to-Scatter Ratio Schedule
Authors: Hosaka Makoto , Ishii Toshiki , Tanaka Asato , Koga Shogo , Hoshizawa Taku
Published: October 2013

We developed an iterative method for optimizing the exposure schedule to obtain a constant signal-to-scatter ratio (SSR) to accommodate various recording conditions and achieve high-density recording. 192 binary images were recorded in the same location of a medium in approximately 300×300 µm2 using an experimental system embedded with a blue laser diode with a 405 nm wavelength and an objective lens with a 0.85 numerical aperture. The recording density of this multiplexing corresponds to 1 Tbit/in.2. The recording exposure time was optimized through the iteration of a three-step sequence consisting of total reproduced intensity measurement, target signal calculation, and recording energy density calculation. The SSR of pages recorded with this method was almost constant throughout the entire range of the reference beam angle. The signal-to-noise ratio of the sampled pages was over 2.9 dB, which is higher than the reproducible limit of 1.5 dB in our experimental system.
High-Density Holographic Data Storage Using Three-Dimensional Shift Multiplexing with Spherical Reference Wave
Authors: Yoshida Shuhei , Kurata Hiroyuki , Ozawa Shohei , Okubo Kaito , Horiuchi Shuma , Ushiyama Zenta , Yamamoto Manabu , Koga Shogo , Tanaka Asato
Published: October 2013

In this study, we propose a three-dimensional shift multiplexing technique using a spherical reference wave. By utilizing a spherical reference wave, multiplex recording is enabled in this system by simply displacing the recording medium. The utilization of a spherical reference wave makes it possible to realize three-dimensional multiplexing, which uses parallel directions of the medium surface and thickness direction. It is also expected that this approach will improve the recording density as compared with the conventional multiplex technique. We report the numerical and experimental evaluation results of our high-density recording and reproduction system based on this principle.