scholarly journals Piezoelectric characterization of lead-free ferroelectric ceramics

2010 ◽  
Vol 4 (3) ◽  
pp. 199-207 ◽  
Author(s):  
Lorena Pardo ◽  
Alvaro García ◽  
Klaus Brebøl ◽  
Lavinia Curecheriu ◽  
Liliana Mitoseriu ◽  
...  
Keyword(s):  
Sol Gel ◽  
Complex Impedance ◽  
Experimental Spectrum ◽  
Lead Free ◽  
Ferroelectric Ceramics ◽  
Coarse Grained ◽  
Shear Mode ◽  
Fine Grained ◽  
Accuracy Test

The challenge to develop high piezoelectric sensitivity and lead-free composition ferro-piezoelectric ceramics has recently dragged new attention to some classic ferroelectrics. Here, Ba(CexTi1-x)O3 (Ce-BT) and 0.94(Bi1/2Na1/2)TiO3-0.06BaTiO3 (BNBT6) ceramics were piezoelectrically characterized from measurements of complex impedance at electromechanical resonances and their analysis by Alemany et al. software. The reconstruction of the spectra for each resonance is used as an accuracy test of the set of calculated coefficients, quantitatively characterized by the regression factor (R2) of such reconstruction to the experimental spectrum. Piezoelectric activity at room temperature (RT) was observed for Ce-BT with x=0.06 and 0.1, ferroelectrics with T(?'max)>RT, but also for x=0.2 with T(?'max)<RT, which confirms its relaxor character (Ps?0 for T?T(?'max)). BNBT6 fine grained ceramics (~1 ?m) were prepared from nanopowder obtained by sol-gel autocombustion. Results obtained for the fine grained ceramic hot-pressed at 800?C for 2 h and recrystallized at 1050?C for 1 h are d33=148 pCN-1 and kp=26.8%. Despite of its lower grain size, the properties of this material are comparable with those reported for coarse grained ceramics obtained by sintering at T>1100?C. Some measurement issues, as the role of the mode coupling on the characterization results, illustrated for the shear mode of a thickness poled plate, are discussed.

Sol-Gel Transparent PLZT Ferroelectric Ceramics

2006 ◽  
Vol 45 ◽  
pp. 2489-2494 ◽  
Author(s):  
M. Płońska ◽  
Wojciech A. Pisarski ◽  
Zbigniew Pędzich ◽  
Zygmunt Surowiak
Keyword(s):  
Infrared Spectroscopy ◽  
Mercury Porosimetry ◽  
Sol Gel ◽  
Ferroelectric Ceramics ◽  
Ceramic Powders ◽  
Lead Lanthanum Zirconate Titanate ◽  
Lanthanum Zirconate ◽  
Pressing Method ◽  
Fine Grained ◽  
To Receive

Lead lanthanum zirconate titanate (known as PLZT) ceramic powders have been prepared by the modified sol – gel method, and underwent consolidation by the hot uniaxial pressing method. Application of such technique of preparation permitted to receive fine-grained transparent PLZT x/65/35 ceramics, with x = 8 -10 La at.%. The present publication gives a detailed account of the relationships between technology and physical properties of obtained materials. To analyze all ceramics SEM, EDS and mercury porosimetry were performed, and dielectric properties were studied too. Quite wide light transparency from the visible to nearinfrared range for PLZT ceramics was detected using optical absorption and infrared spectroscopy.

scholarly journals Tye’s Theory of the Unconceptual Content of the Perceptual Mental States

Discourse ◽  
2019 ◽  
Vol 5 (4) ◽  
pp. 18-25
Author(s):  
A. I. Ponomarev
Keyword(s):  
Research Work ◽  
Mental States ◽  
Coarse Grained ◽  
Nonconceptual Content ◽  
Conceptual Content ◽  
Fine Grained ◽  
The Third ◽  
Philosophy Of Perception ◽  
Cognitive Research

Introduction. In modern philosophy of perception, the issue of the content of perceptual mental states is actively discussed, in particular the possibility of nonconceptual content is one of the most significant problem. Usually conceptual activity is attributed to thinking, and perception is intended to be non-conceptual. Such an approach may deprive perception of opportunity to serve as a basis for judgment. The paper analyzes Tye’s theory of non-conceptual content of perceptual mental states, which does not deprive the perception of its epistemological function.Methodology and sources. Methodologically, the research work is based on philosophical analysis of modern theories of perception and results of cognitive research.Results and discussion. In accepted terminology, the content of perceptual mental states can be of three types: conceptual, non-conceptual detailed (fine-grained) and nonconceptual coarse (coarse-grained). Tye's position is that perceptual mental states have only the third kind of content. This approach faces a number of objections that are presented in this paper. The analysis of objections shows their surmount ability, thus, it can be concluded that the Tye’s position of nonconceptual content can be considered as reasonable. The main result of the presented research is the presentation of additional grounds for the theory of non-conceptual content of perceptual mental states.Conclusion. The problem of the content of perceptual mental states is crucial for understanding the epistemological role of perception. The theory of non-conceptual content of perceptual mental states provides new insights into perception.

Observations on brucite formation and the role of brucite in Iowa highway concrete deterioration

2002 ◽  
Vol 8 (2) ◽  
pp. 137-145 ◽  
Author(s):  
Hyomin Lee ◽  
Robert D. Cody ◽  
Anita M. Cody ◽  
Paul G. Spry
Keyword(s):  
Cement Paste ◽  
Direct Evidence ◽  
Crystal Surface ◽  
Conclusive Evidence ◽  
Coarse Grained ◽  
Fine Grained ◽  
Coarse Aggregates ◽  
Concrete Deterioration ◽  
Direct Precipitation

Abstract Iowa highway concretes containing reactive dolomite, (CaMg) 2 CO 3 , aggregate, composed of fine-grained, microporous dolomite, sometimes have service lives of less than 10 years. This premature deterioration may, in part, be caused by expansive forces created by newly formed minerals such as brucite, Mg (OH) 2 , in the cement paste as a result of dedolomitization of reactive dolomite coarse aggregate. Although calcite is the most abundant secondary mineral in cements of poorly-performing concretes, the present study found no evidence that it was expansionary. Brucite is common but less abundant than calcite and occurred chiefly in and near the margins of reactive dolomite in both the aggregate and cement paste of poorly-performing concretes. Most brucite occurs in partially dedolomitized rims around dolomite coarse aggregates. This type of brucite is widely disseminated through the rims, consists of extremely small (<1 m) microcrystalline masses, and was produced by direct precipitation from pore solutions. Smaller amounts of brucite occur in the cement paste. This type is relatively coarse-grained (10 mu m-20 mu m) and most was formed primarily by crystal surface mediated (topochemical) reactions between magnesium-rich pore solutions and portlandite, Ca(OH) 2 . Numerous microcracks are present in cement paste but are not spatially associated with brucite locations. There is no direct evidence for cracking caused by brucite but this is not conclusive evidence against brucite-induced expansion. Brucite is widely disseminated so that expansion at innumerable micro-locations may cause general concrete expansion which should be relieved by cracking at weaker locations in the concretes.

Lead-free piezoelectrics: Current status and perspectives

2013 ◽  
Vol 03 (02) ◽  
pp. 1330002 ◽  
Author(s):  
Indrani Coondoo ◽  
Neeraj Panwar ◽  
Andrei Kholkin
Keyword(s):  
Lead Zirconate Titanate ◽  
Structural Engineering ◽  
Piezoelectric Properties ◽  
Sol Gel ◽  
Lead Free ◽  
Ferroelectric Ceramics ◽  
Current Status ◽  
Structure Property ◽  
Piezoelectric Energy ◽  
Recent Developments

In the last few years, there has been tremendous effort to develop lead-free ferroelectric ceramics with high piezoelectric properties by various doping and alloying routes. Several material systems have been explored, however, no prominent alternative to the versatile lead zirconate titanate (PZT) system has been found yet. Despite the achieved improvement in piezoelectric properties, there are problems in the synthesis, processing and poling of the sintered ceramics. Various processing techniques including microwave, hydrothermal, sol–gel, Pechini and spark plasma sintering have been used to overcome the drawbacks related to synthesis issues. In this paper, an attempt is made to review recent developments on lead-free piezo materials emphasizing their preparation, structure–property relations, and consequent physical properties. In this context, both compositional and structural engineering approaches to achieve acceptable piezoelectric properties in lead-free materials are discussed. Piezoelectric properties of the most promising lead-free compositions/families including titanates, alkaline niobates and bismuth perovskites and their solid solutions, along with non-perovskites such as bismuth layer-structured ferroelectrics are reviewed in detail. A brief coverage of the recent developments in the area of piezoelectric energy harvesting is also encompassed.

scholarly journals Thermo-Structural Evolution of the Val Malenco (Italy) Peridotite: A Petrological, Geochemical and Microstructural Study

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 962
Author(s):  
Wenlong Liu ◽  
Yi Cao ◽  
Junfeng Zhang ◽  
Yanfei Zhang ◽  
Keqing Zong ◽  
...  
Keyword(s):  
Strain Localization ◽  
Structural Evolution ◽  
Coarse Grained ◽  
Prograde Metamorphism ◽  
Fine Grained ◽  
Tectonic History ◽  
Serpentinized Peridotite ◽  
Geochemical Study ◽  
Dissolution And Precipitation

The Val Malenco peridotite massif is one of the largest exposed ultramafic massifs in Alpine orogen. To better constrain its tectonic history, we have performed a comprehensive petro-structural and geochemical study. Our results show that the Val Malenco serpentinized peridotite recorded both pre-Alpine extension and Alpine convergence events. The pre-Alpine extension is recorded by microstructural and geochemical features preserved in clinopyroxene and olivine porphyroblasts, including partial melting and refertilisation, high-temperature (900–1000 °C) deformation and a cooling, and fluid-rock reaction. The following Alpine convergence in a supra-subduction zone setting is documented by subduction-related prograde metamorphism features preserved in the coarse-grained antigorite and olivine grains in the less-strained olivine-rich layers, and later low-temperature (<350 °C) serpentinization in the fine-grained antigorite in the more strained antigorite-rich layers. The strain shadow structure in the more strained antigorite-rich layer composed of dissolving clinopyroxene porphyroblast and the precipitated oriented diopside and olivine suggest dissolution and precipitation creep, while the consistency between the strain shadow structure and alternating less- and more-strained serpentinized domains highlights the increasing role of strain localization induced by the dissolution-precipitation creep with decreasing temperature during exhumation in Alpine convergence events.

scholarly journals Compaction Characteristics and Minimum Void Ratio Prediction Model for Gap-Graded Soil-Rock Mixture

2018 ◽  
Vol 8 (12) ◽  
pp. 2584 ◽  
Author(s):  
Tao Wang ◽  
Sihong Liu ◽  
Yan Feng ◽  
Jidu Yu
Keyword(s):  
Prediction Model ◽  
Void Ratio ◽  
Particle Breakage ◽  
Coarse Grained ◽  
Test Results ◽  
Inhomogeneous Materials ◽  
Compaction Characteristics ◽  
Fine Grained ◽  
Compaction Test

Gap-graded soil-rock mixtures (SRMs), composed of coarse-grained rocks and fine-grained soils particles, are very inhomogeneous materials and widely encountered in geoengineering. In geoengineering applications, it is necessary to know the compaction characteristics in order to estimate the minimum void ratio of gap-graded SRMs. In this paper, the void ratios of compacted SRMs as well as the particle breakage during vibrating compaction were investigated through a series of vibrating compaction tests. The test results show that gap-graded SRMs may reach a smaller void ratio than the SRM with a continuous gradation under some circumstances. When the particles in a gap interval play the role of filling components, the absence of them will increase the void ratio of the SRM. The particle breakage of gap-graded SRMs is more prominent than the SRM with continuous gradation on the whole, especially at the gap interval of 5–20 mm. Based on the test results, a minimum void ratio prediction model incorporating particle breakage during compaction is proposed. The developed model is evaluated by the compaction test results and its validation is discussed.

scholarly journals Controlling the high temperature deformation behavior and thermal stability of ultra-fine-grained W by re alloying

2021 ◽  
Author(s):  
Johann Kappacher ◽  
Oliver Renk ◽  
Daniel Kiener ◽  
Helmut Clemens ◽  
Verena Maier-Kiener
Keyword(s):  
High Temperature ◽  
Peierls Stress ◽  
Coarse Grained ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Fine Grained ◽  
Boundary Interaction ◽  
Kink Pair ◽  
Fine Grain

Abstract Due to their outstanding properties, ultra-fine-grained tungsten and its alloys are promising candidates to be used in harsh environments, hence it is crucial to understand their high temperature behavior and underlying deformation mechanisms. Therefore, advanced nanoindentation techniques were applied to ultra-fine-grained tungsten–rhenium alloys up to 1073 K. A continuous hardness decrease up to 0.2 $$T_{\text{m}}$$ T m is rationalized by a still dominating effect of the Peierls stress. However, the absence of well-established effects of Rhenium alloying, resulting in a reduced temperature dependence of strength for coarse-grained microstructures, was interpreted as an indication for a diminishing role of kink-pair formation in ultra-fine-grained metals with sufficiently fine grain size. Despite slight grain growth in W, dislocation–grain boundary interaction was identified as the dominating deformation mechanism above 0.2 $$T_{\text{m}}$$ T m . Interaction and accommodation of lattice dislocations with grain boundaries was affected by a reduced boundary diffusivity through alloying with Re. Graphic abstract

scholarly journals The Linguistic Formulation of Fallacies Matters: The Case of Causal Connectives

Argumentation ◽  
2020 ◽  
Author(s):  
Jennifer Schumann ◽  
Sandrine Zufferey ◽  
Steve Oswald
Keyword(s):  
Empirical Study ◽  
Coarse Grained ◽  
Controlled Experiments ◽  
Corpus Study ◽  
Fine Grained ◽  
Discourse Connectives

Abstract While the role of discourse connectives has long been acknowledged in argumentative frameworks, these approaches often take a coarse-grained approach to connectives, treating them as a unified group having similar effects on argumentation. Based on an empirical study of the straw man fallacy, we argue that a more fine-grained approach is needed to explain the role of each connective and illustrate their specificities. We first present an original corpus study detailing the main features of four causal connectives in French that speakers routinely use to attribute meaning to another speaker (puisque, étant donné que, vu que and comme), which is a key element of straw man fallacies. We then assess the influence of each of these connectives in a series of controlled experiments. Our results indicate each connective has different effects for the persuasiveness of straw man fallacies, and that these effects can be explained by differences in their semantic profile, as evidenced in our corpus study. Taken together, our results demonstrate that connectives are important for argumentation but should be analyzed individually, and that the study of fallacies should include a fine-grained analysis of the linguistic elements typically used in their formulation.

Correlation between dislocation, grain boundary and interface of duplex SS in stress corrosion cracking(SCC)

1990 ◽  
Vol 48 (4) ◽  
pp. 928-929
Author(s):  
Wang Zheng-fang ◽  
Z.F. Wang
Keyword(s):  
Stainless Steel ◽  
Thermal Cycle ◽  
Secondary Phase ◽  
Corrosion Cracking ◽  
Coarse Grained ◽  
Test Environment ◽  
Fine Grained ◽  
Evaluation Test ◽  
Welding Thermal Cycle ◽  
Micro Analysis

The main purpose of this study highlights on the evaluation of chloride SCC resistance of the material,duplex stainless steel,OOCr18Ni5Mo3Si2 (18-5Mo) and its welded coarse grained zone(CGZ).18-5Mo is a dual phases (A+F) stainless steel with yield strength:512N/mm2 .The proportion of secondary Phase(A phase) accounts for 30-35% of the total with fine grained and homogeneously distributed A and F phases(Fig.1).After being welded by a specific welding thermal cycle to the material,i.e. Tmax=1350°C and t8/5=20s,microstructure may change from fine grained morphology to coarse grained morphology and from homogeneously distributed of A phase to a concentration of A phase(Fig.2).Meanwhile,the proportion of A phase reduced from 35% to 5-10°o.For this reason it is known as welded coarse grained zone(CGZ).In association with difference of microstructure between base metal and welded CGZ,so chloride SCC resistance also differ from each other.Test procedures:Constant load tensile test(CLTT) were performed for recording Esce-t curve by which corrosion cracking growth can be described, tf,fractured time,can also be recorded by the test which is taken as a electrochemical behavior and mechanical property for SCC resistance evaluation. Test environment:143°C boiling 42%MgCl2 solution is used.Besides, micro analysis were conducted with light microscopy(LM),SEM,TEM,and Auger energy spectrum(AES) so as to reveal the correlation between the data generated by the CLTT results and micro analysis.

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