bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dielectric and electric relaxations induced by the complex defect clusters in (Yb+Nb) co‐doped rutile TiO2 ceramics
Authors: Zhao Xiao‐gang , Liu Peng 
Published: April 2017

AbstractThe effect of the Yb+Nb substitution for Ti on the microstructure, crystal structures, and dielectric properties of (Yb1/2Nb1/2)xTi1−xO2 (0.01≤x≤0.1) ceramics is investigated in this study. The results reveal that the solid solubility limit of the (Yb1/2Nb1/2)xTi1−xO2 ceramics is x=0.07, and the average grain sizes considerably decrease from 12 μm to 6 μm with x increasing from 0.01 to 0.1. Three types of dielectric relaxations are observed at temperature ranges of 10‐30 K, 80‐180 K, and 260‐300 K, caused by the electron‐pinned defect dipoles, polaron hopping, and interfacial polarizations, respectively. The conduction mechanism changes from nearest‐neighbor‐hopping to polaron hopping mechanism, which is confirmed by ac conductivity measurements. The present work indentifies the correlation between the colossal permittivity and polaron hopping process in the titled compound.
Long persistent properties of CaGa2O4:Bi3+ at different ambient temperature
Authors: Wang Shaobo , Chen Wenbo , Zhou Dacheng , Qiu Jianbei , Xu Xuhui , Yu Xue 
Published: April 2017

AbstractA yellow long persistent luminescence (LPL) phosphor of CaGa2O4:Bi3+ (CGO:Bi) is developed, of which the LPL can be visually recognized (0.32 mcd m−2) over 36 hours after the removal of the excitation source. Furthermore, an excellent LPL performance above the room temperature and unusual thermal quenching behavior are observed. The thermoluminescence (TL) curves indicate that the continuity of the traps structure with different depths is a key factor in ensuring that carriers could be released from deep traps above room temperature successively. The work verifies unambiguously that the continuous defect‐state structure is beneficial to the LPL temperature resistant abilities, which would provide a reasonable approach to design new LPL phosphors in extreme environments.
Phase transitions and glass transition in a hyperquenched silica‐alumina glass
Authors: Zhang Yanfei , Zhao Donghui , Yue Yuanzheng 
Published: April 2017

AbstractWe investigate phase transitions, glass transition, and dynamic behavior in the hyperquenched 69SiO2–31Al2O3 (mol%) glass (SA glass). Upon reheating, the SA glass exhibits a series of thermal responses. Subsequent to the sub‐Tg enthalpy release, the glass undergoes a large jump in isobaric heat capacity (ΔCp) during glass transition, implying the fragile nature of the SA glass. The mullite starts to form before the end of glass transition, indicating that the SA glass is extremely unstable against crystallization. After the mullite formation, the remaining glass phase exhibits an increased Tg and a suppressed ΔCp. The formation of cristobalite at 1553 K indicates the dominance of silica in the remaining glass matrix. The cristobalite gradually re‐melts as the isothermal heat‐treatment temperature is raised from 1823 to 1853 K, which is well below the melting point of cristobalite, while the amount of the mullite remains unchanged.
The role of ceramic and glass science research in meeting societal challenges: Report from an NSF‐sponsored workshop
Authors: Faber Katherine T. , Asefa Tewodros , Backhaus‐Ricoult Monika , Brow Richard , Chan Julia Y. , Dillon Shen , Fahrenholtz William G. , Finnis Michael W. , Garay Javier E. , García R. Edwin , Gogotsi Yury , Haile Sossina M. , Halloran John , Hu Juejun , Huang Liping , Jacobsen Steven D. , Lara‐Curzio Edgar , LeBeau James , Lee William E. , Levi Carlos G. , Levin Igor , Lewis Jennifer A. , Lipkin Don M. , Lu Kathy , Luo Jian , Maria Jon‐Paul , Martin Lane W. , Martin Steve , Messing Gary , Navrotsky Alexandra , Padture Nitin P. , Randall Clive , Rohrer Gregory S. , Rosenflanz Anatoly , Schaedler Tobias A. , Schlom Darrell G. , Sehirlioglu Alp , Stevenson Adam J. , Tani Toshihiko , Tikare Veena , Trolier‐McKinstry Susan , Wang Hong , Yildiz Bilge 
Published: April 2017

AbstractUnder the sponsorship of the U.S. National Science Foundation, a workshop on emerging research opportunities in ceramic and glass science was held in September 2016. Reported here are proceedings of the workshop. The report details eight challenges identified through workshop discussions: Ceramic processing: Programmable design and assembly; The defect genome: Understanding, characterizing, and predicting defects across time and length scales; Functionalizing defects for unprecedented properties; Ceramic flatlands: Defining structure‐property relations in free‐standing, supported, and confined two‐dimensional ceramics; Ceramics in the extreme: Discovery and design strategies; Ceramics in the extreme: Behavior of multimaterial systems; Understanding and exploiting glasses and melts under extreme conditions; and Rational design of functional glasses guided by predictive modeling. It is anticipated that these challenges, once met, will promote basic understanding and ultimately enable advancements within multiple sectors, including energy, environment, manufacturing, security, and health care.
Bismuth sodium titanate lead‐free piezoelectric coatings by thermal spray process
Authors: Guo Kun , Chen Shuting , Tan Chee Kiang Ivan , Sharifzadeh Mirshekarloo Meysam , Yao Kui , Tay Francis Eng Hock 
Published: April 2017

AbstractBismuth sodium titanate (BNT) piezoelectric ceramic coatings with dense morphology and single perovskite phase were fabricated by thermal spray process. The melting and crystallization behaviors of BNT near congruent composition and the effect of excess Bi composition were investigated by analyzing the heating‐melting‐cooling cycle for the application in thermal spray process. Crystal structure and morphology of the thermal sprayed BNT coatings were examined, and their electrical and electromechanical properties were tested. An effective piezoelectric coefficient d33 of 50 pm/V was obtained under substrate clamping, measured with laser scanning method. The findings have shed light on the design of appropriate compositions for achieving high quality lead‐free piezoelectric ceramic coatings by the scalable thermal spray process.
Enhanced photocatalytic performance of Bi2Fe4O9/graphene via modifying graphene composite
Authors: Liu Pengdong , Sun Huajun , Liu Xiaofang , Sui Huiting , Zhang Yong , Zhou Dingguo , Guo Qinghu , Ruan Yong 
Published: April 2017

AbstractBi2Fe4O9 (BFO) is one of the most important photocatalyst materials and its composition with graphene may leave an optimizing effect on the photocatalytic performance. In this paper, reduced graphene oxide (RGO) with various contents is selected to be composited with BFO successfully via one‐step hydrothermal method. A series of BFO‐xRGO (x=0, 1.25, 2.50, 3.75, 5, 6.25, and 7.50 wt.%) were prepared and the effects of RGO content on crystalline, light absorption, impedance, and photocatalytic degradation rate of methyl violet (MV) solution are characterized. The entire film samples exhibit enhanced photocatalytic efficiency. Especially, with 5 wt.% RGO content added, the film sample shows the best photocatalytic degradation efficiency with a MV solution degradation rate of 95%. This implies that the composition of RGO allows BFO‐based thin film as an efficient photocatalyst candidate, and as well, the BFO/RGO composite possesses the potential for better use in the related photocatalyst applications.
Three‐dimensional mapping of crystalline ceramic waste form materials
Authors: Cocco Alex P. , DeGostin Matthew B. , Wrubel Jacob A. , Damian Peter J. , Hong Tao , Xu Yun , Liu Yijin , Pianetta Piero , Amoroso Jake W. , Brinkman Kyle S. , Chiu Wilson K. S. 
Published: April 2017

AbstractThis work demonstrates the use of synchrotron‐based, transmission X‐ray microscopy (TXM) and scanning electron microscopy to image the 3‐D morphologies and spatial distributions of Ga‐doped phases within model, single‐ and two‐phase waste form material systems. Gallium doping levels consistent with those commonly used for nuclear waste immobilization (e.g., Ba1.04Cs0.24Ga2.32Ti5.68O16) could be readily imaged. The analysis suggests that a minority phase with different stoichiometry/composition from the primary hollandite phase can be formed by the solid‐state ceramic processing route with varying morphology (globular vs. cylindrical) as a function of Cs content. The results presented in this work represent a crucial step in developing the tools necessary to gain an improved understanding of the microstructural and chemical properties of waste form materials that influence their resistance to aqueous corrosion. This understanding will aid in the future design of higher durability waste form materials.
Multilayer lead‐free piezoceramic composites: Influence of co‐firing on microstructure and electromechanical behavior
Authors: Ayrikyan Azatuhi , Weyland Florian , Steiner Sebastian , Duerrschnabel Michael , Molina‐Luna Leopoldo , Koruza Jurij , Webber Kyle G. 
Published: April 2017

AbstractIn this study lead‐free 2‐2 and 0‐3 ceramic/ceramic composites comprised of the non‐ergodic relaxor 0.93(Bi1/2Na1/2)TiO3–0.07BaTiO3 and ergodic relaxor 0.94Bi0.5(Na0.75K0.25)0.5TiO3–0.06BiAlO3 were investigated. The macroscopic electromechanical behavior was characterized as a function of continuent content, revealing an enhancement in the unipolar strain from the multilayer composite structure. Systematic evaluation of the effects of co‐sintering on microstructural properties, such as grain size and porosity, revealed potential mechanisms by which the increase in unipolar strain was achieved. In addition, interdiffusion between the constituents was observed, providing evidence for the formation of a functionally graded ceramic by co‐sintering. These data are contrasted with high‐resolution energy dispersive X‐ray microanalysis for measurement of chemical composition across the interface of 2‐2 ceramics. These findings provide insight into how synthesis routes can be optimized for tailoring the enhancement of electromechanical properties of lead‐free electroceramic composite systems.
Structural elucidation and iron oxidation states in situ formed β‐Ca3(PO4)2/α‐Fe2O3 composites
Authors: Nandha Kumar Ponnusamy , Mishra Sandeep K. , Kannan Sanjeevi 
Published: April 2017

AbstractA detailed structural analysis on the in situ synthesized β‐Ca3(PO4)2/α‐Fe2O3 composites is demonstrated. Compositional ratios, the influence and occupancy of iron at the β‐Ca3(PO4)2 lattice, oxidation state of iron in the composites are derived from analytical techniques involving XRD, FT‐IR, Raman, refinement of the powder X‐ray diffraction and X‐ray photoelectron spectroscopy. Iron exists in the Fe3+ state throughout the investigated systems and favors its occupancy at the Ca2+(5) site of β‐Ca3(PO4)2 until critical limit, and thereafter crystallizes as α‐Fe2O3 at ambient conditions. Fe3+ occupancy at the β‐Ca3(PO4)2 lattice yields a Ca9Fe(PO4)7 structure that is isostructural with its counterpart. A strong rise in the soft ferromagnetic behavior of β‐Ca3(PO4)2/α‐Fe2O3 composites is obvious that depends on the content of α‐Fe2O3 in the composites. Overall, the diverse level of iron inclusions at the calcium phosphate system with a Ca/P ratio of 1.5 yields a structurally stable β‐Ca3(PO4)2/α‐Fe2O3 composites with assorted compositional ratios.
Effect of lead content on the performance of niobium‐doped {100} textured lead zirconate titanate films
Authors: Borman Trent M. , Zhu Wanlin , Wang Ke , Ko Song Won , Mardilovich Peter , Trolier‐McKinstry Susan E. 
Published: April 2017

AbstractNiobium‐doped, {100} textured, gradient‐free, lead zirconate titanate (PZT) films were fabricated from solutions with different lead contents. Film lead content was controlled through changes in the average solution lead excess from 14.7% to 17 at.%. The low field dielectric response as well as the polarization‐electric field hysteresis loops were not a strong function of lead content. However, films with lower lead contents in the precursor tended to withstand higher poling fields than films prepared from more lead‐rich precursors. Although no residual PbO was observed at the grain boundaries, films prepared from more lead‐rich solutions had higher levels of grain‐boundary porosity, lower breakdown strengths, and lower threshold electric fields at which cracking was observed.
Geopolymer foams obtained by the saponification/peroxide/gelcasting combined route using different soap foam precursors
Authors: Cilla Marcelo S. , de Mello Innocentini Murilo D. , Morelli Márcio R. , Colombo Paolo 
Published: April 2017

AbstractThis work investigates the influence of eight different vegetable and animal sources of fatty acids as soap foam precursors in the processing of highly porous geopolymers. Four sources rich in saturated chains (coconut and babassu oils, palm stearin and beef tallow), two sources rich in monounsaturated chains (olive and castor oils) and two sources rich in polyunsaturated chains (sunflower oil and soybean biodiesel) were selected. For all soap precursors, bodies treated at 300°C possessed a very high total porosity (84‐88 vol%), open porosity (79‐85 vol%) and relatively high specific surface area (35.1‐63.5 m2/g), but rather low compressive strength (0.2‐0.4 MPa). The increase in the thermal treatment temperature caused a slight decrease in porosity but a substantial increase in compressive strength and decrease in specific surface area due to sintering and formation of crystalline phases. The Darcian permeability coefficients of all bodies (0.6‐10.6×10−10 m2) were typical of gelcasted foams, aerosol filters and fibrous mats. The morphology of pores could be well‐associated to the features of lathers produced by the respective soap precursors.
Thermal annealing effects on the energy storage properties of BST ceramics
Authors: Song Zhe , Liu Hanxing , Lanagan Michael T , Zhang Shujun , Hao Hua , Cao Minghe , Yao Zhonghua , Fu Zhenxiao , Huang Kun 
Published: April 2017

AbstractThermal annealing treatments with different atmospheres (air, oxygen, and reducing atmospheres, respectively) were employed for the conventionally sintered (Ba0.4Sr0.6)TiO3 (BST) ceramics. The effect of thermal annealing on the energy storage properties of BST ceramics was investigated, where oxygen vacancies played an important role. The dielectric loss, bulk resistivity and dielectric breakdown strength (BDS) were found to be sensitive to the annealing process, leading to the different energy densities in the range of 0.30‐0.80 J/cm3. Temperature‐dependent dielectric measurement and thermally stimulated depolarization current analysis were conducted to understand the impacts of oxygen vacancies on the macroscopic properties, which were found to be closely associated with the annealing conditions.
Electric current‐controlled synthesis of BaTiO3
Authors: Nakagawa Yu , Yoshida Hidehiro , Uehashi Akinori , Tokunaga Tomoharu , Sasaki Katsuhiro , Yamamoto Takahisa 
Published: April 2017

AbstractIn BaTiO3, flash‐sintering associated with a surge of the specimen electric current sometimes results in an inhomogeneous microstructure including Ti‐excess secondary phases because of discharging. We applied field‐assisted sintering technique (FAST) under precisely controlled specimen current that was set just below the threshold value for the occurrence of flash event for BaTiO3, to avoid the occurrence of the discharging. As a result, uniform and fine‐grained compacts were obtained without any secondary phases. A relative density of approximately 92% was achieved under FAST condition of 100 V/cm with a limiting current of 72 mA and soaking time of 3 hours at 1070°C. The voltages during sintering under a constant current of 72 mA were found to decrease during the soaking process. Electron energy loss spectroscopy revealed the generation of excess oxygen vacancies at/near grain boundaries. The excess oxygen vacancies induced by application of DC electric fields were confirmed to reduce the voltages and to retard the shrinkage rate in a final sintering stage.
A comprehensive sintering mechanism for TBCs‐Part II: Multiscale multipoint interconnection‐enhanced initial kinetics
Authors: Li Guangrong , Xie Hua , Yang Guanjun , Liu Gang , Li Chengxin , Li Changjiu 
Published: April 2017

AbstractDuring thermal exposure, the sintering process of the plasma‐sprayed thermal barrier coatings (PS‐TBCs) presents significant two‐stage kinetics, as reported in the Part I. As a companion study, this part aims to reveal the mechanism responsible for the ultrafast sintering kinetics when initially exposed, since the initial short stage (stage‐I) often finishes most increment of the mechanical and thermal properties. A detailed examination of the pore healing behavior was carried out, based on the experimental result in Part I that the dominant structural change at the stage‐I is the significant healing at intersplat pore tips. Results show that the smooth splat surface, which made up the wedge‐shaped intersplat pores, changed to a rough surface with multiscale convexs after high‐temperature thermal exposure. Moreover, the multiscale roughening is highly sensitive to various orientations of the columnar grains inside the splats. Subsequently, multipoint connection between the counter‐surfaces of the intersplat pores was formed by the bridging of multiscale convexs. This multiscale multipoint connection between pore surfaces significantly accelerated the healing of intersplat pores, which can be dominantly responsible for the ultrafast sintering kinetics at the stage‐I. This comprehensive sintering mechanism could offer some positive suggestions toward prolonging the thermal‐insulating effect of TBCs.
Tailored approach for management of ventricular tachycardia in cardiac sarcoidosis
Authors: Yalagudri Sachin , Zin Thu Ngwe , Devidutta Soumen , Saggu Daljeet , Thachil Ajit , Chennapragada Sridevi , Narasimhan Calambur 
Published: April 2017

AbstractIntroductionTreating ventricular tachycardia (VT) in patients with cardiac sarcoidosis (CS) is challenging as patients present in different phase of the disease (inflammatory, scar, or sometimes both). A customized approach to treatment is required for better outcomes. We describe our experience in the management of VT in CS based on the phase of the disease.Methods and resultsPatients were considered to have myocardial inflammation if there was an increased myocardial 18fluorodeoxy glucose (FDG) uptake in PET‐CT scan of the chest (n = 14). These patients were treated with antiarrhythmic drugs (AADs) and immunosuppression. Patients with scar related VT (without active inflammation) were managed with AADs and underwent radiofrequency ablation (RFA) if unresponsive to drug therapy (n = 4). Patients previously treated for CS who presented with VT and evidence of reactivation (abnormal FDG uptake) after a quiescent period of 6 months were treated with intensified immunosuppression alongside AADs (n = 3/14). Patients with myocardial inflammation responded well to immunosuppression. Patients with drug resistant VT in the scar phase responded well to RFA. Four patients in the inflammatory group had recurrence of VT during follow‐up of whom 3 were found to have disease reactivation. Intensified immunosuppression suppressed VT in all 3 patients. In 1 patient, VT recurrence was found to be scar related and required RFA for control.ConclusionTailoring therapy for VT in CS according to the phase of disease results in good clinical outcome and avoids unnecessary immunosuppression.
Study of the wearable cardioverter defibrillator in advanced heart‐failure patients (SWIFT)
Authors: Barsheshet Alon , Kutyifa Valentina , Vamvouris Theodora , Moss Arthur J. , Biton Yitschak , Chen Leway , Storozynsky Eugene , Wan Chingping , Szymkiewicz Steven J. , Goldenberg Ilan 
Published: April 2017

AbstractIntroductionThe wearable cardioverter defibrillator (WCD) may allow stabilization until reassessment for an implantable cardioverter defibrillator (ICD) among high‐risk heart failure (HF) patients. However, there are limited data on the WCD benefit in the acute decompensated HF setting.Methods and resultsThe Study of the Wearable Cardioverter Defibrillator in Advanced Heart Failure Patients (SWIFT) was a prospective clinical trial carried out at two medical centers. Patients hospitalized with advanced HF symptoms and reduced left ventricular ejection function (LVEF) were enrolled and prescribed a WCD prior to discharge for a total of 3 months. Outcome measures included arrhythmic events, WCD discharge, and death. Study patients (n = 75, mean age 51 ± 14 years, 31% women) had a mean LVEF of 21.5 ± 10.4%. Non‐ischemic cardiomyopathy was present in 66% of patients. The median WCD wearing time was 59 (interquartile range 17–97) days, and 80% of patients wore the device >50% of daily hours. WCD interrogations showed a total of 8 arrhythmic events in 5 patients, including 3 nonsustained or self‐terminating ventricular tachycardia (VT) events, and one polymorphic VT successfully terminated by the WCD. None of the patients died while wearing the device and no inappropriate device therapies occurred. Upon termination of treatment with the WCD, 21 patients (28%) received an ICD. At 3 years, the cumulative death rate was 20% in the ischemic and 21% in non‐ischemic cardiomyopathy patients.ConclusionA management strategy incorporating the WCD can be safely used to bridge the decision regarding the need for ICD implantation in high‐risk patients with advanced HF.
Immunophenotyping and activation status of maternal peripheral blood leukocytes during pregnancy and labour, both term and preterm
Authors: Zhang Jianhong , Shynlova Oksana , Sabra Sally , Bang Annie , Briollais Laurent , Lye Stephen J. 
Published: April 2017

AbstractThe onset of labour in rodents and in humans is associated with physiological inflammation which is manifested by infiltration of activated maternal peripheral leukocytes (mPLs) into uterine tissues. Here, we used flow cytometry to immunophenotype mPLs throughout gestation and labour, both term and preterm. Peripheral blood was collected from non‐pregnant women and pregnant women in the 1st, 2nd and 3rd trimesters. Samples were also collected from women in active labour at term (TL) or preterm (PTL) and compared with women term not‐in‐labour (TNIL) and preterm not‐in‐labour (PTNIL). Different leukocyte populations were identified by surface markers such as CD45, CD14, CD15, CD3, CD4, CD8, CD19 and CD56. Their activation status was measured by the expression levels of CD11b, CD44, CD55, CD181 and CD192 proteins. Of all circulating CD45+ leukocytes, we detected significant increases in CD15+ granulocytes (i) in pregnant women versus non‐pregnant; (ii) in TL women versus TNIL and versus pregnant women in the 1st/2nd/3rd trimester; (iii) in PTL women versus PTNIL. TL was characterized by (iv) increased expressions of CD11b, CD55 and CD192 on granulocytes; (v) increased mean fluorescent intensity (MFI) of CD55 and CD192 on monocytes; (vi) increased CD44 MFI on CD3+ lymphocytes as compared to late gestation. In summary, we have identified sub‐populations of mPLs that are specifically activated in association with gestation (granulocytes) or with the onset of labour (granulocytes, monocytes and lymphocytes). Additionally, beta regression analysis created a set of reference values to rank this association between immune markers of pregnancy and to identify activation status with potential prognostic and diagnostic capability.