Processing by both classical and mechanosynthesis routes and characterization of a new solid solution of tungsten-bronze structure ceramics

International Nuclear Information System (INIS)

Khachane, M.; Moure, A.; Elaatmani, M.; Zegzouti, A.; Daoud, M.; Castro, A.

2006-01-01

A new family of ferroelectric compounds with Ba 2-x Na 1+x Li x Nb 5 O 15 composition (0 ≤ x ≤ 1) and tetragonal tungsten-bronze structure is processed for the first time. This new family of materials derived from Ba 2 NaNb 5 O 15 compound was processed by classical solid-state reaction and by mechanosynthesis. The powders prepared by these two routes were characterized by X-ray diffraction (at room and high temperature), differential thermal analysis, thermogravimetry and scanning electron microscopy. The results confirm the formation of the solid solution in the whole range of composition. The influence of Li addition on the dielectric permittivity and losses and on the ferro-paraelectric transition temperature is also studied

New Research on Bronze Age Textile Production

DEFF Research Database (Denmark)

Andersson, Eva Birgitta; Mårtensson, Linda; Nosch, Marie-Louise Bech

2008-01-01

presentation of the results from the systematic tests with Bronze Age textile tools. results concerning mesurements of lenght and time consumed.......presentation of the results from the systematic tests with Bronze Age textile tools. results concerning mesurements of lenght and time consumed....

Corrosion evaluation of traditional and new bronzes for artistic castings

International Nuclear Information System (INIS)

Chiavari, C.; Colledan, A.; Frignani, A.; Brunoro, G.

2006-01-01

By electrochemical and accelerated weathering tests, the corrosion behaviour of a new type of tin-bronze, containing about 3 wt.% silicon (SI3 bronze) was compared to a traditional 5% Sn, 5% Zn, 5% Pb bronze used for artistic castings (G85 bronze) under conditions simulating urban-industrial and marine environments. The aggressive media were: a synthetic pH 3.1 acid rain (AR) solution; a typical moist SO 2 -NO x for a climatic chamber and AR or 3.5% NaCl aqueous solution for salt spray cabinet. In all the environments the corrosion product layers formed on SI3 bronze were more uniform and protective than those formed on the traditional G85 bronze. The nature and morphology of the corrosion products were investigated by X-ray diffraction (XRD), optical and scanning electron microscopy with microprobe (SEM-EDS), atomic force microscopy (AFM)

77 FR 14600 - Pricing for 2012 Kennedy Half-Dollar Bags and Rolls, Bronze Medals, the First Spouse Bronze Medal...

Science.gov (United States)

2012-03-12

... DEPARTMENT OF THE TREASURY United States Mint Pricing for 2012 Kennedy Half-Dollar Bags and Rolls, Bronze Medals, the First Spouse Bronze Medal Set and the Birth Set AGENCY: United States Mint, Department of the Treasury. ACTION: Notice. SUMMARY: The United States Mint is announcing 2012 pricing for...

Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

Science.gov (United States)

Tuttle, James E.; Canavan, Edgar; DiPirro, Michael

2009-01-01

Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, there is significant variation among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). The heat conducted into the JWST instrument stage is dominated by these harnesses, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to just keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment which measured the electrical and thermal conductivity of this material between 4 and 295 Kelvin.

Stabilization of metastable tetragonal zirconia nanocrystallites by surface modification

DEFF Research Database (Denmark)

Nielsen, Mette Skovgaard; Almdal, Kristoffer; Lelieveld, A. van

2011-01-01

Metastable tetragonal zirconia nanocrystallites were studied in humid air and in water at room temperature (RT). A stabilizing effect of different surfactants on the tetragonal phase was observed. Furthermore, the phase stability of silanized metastable tetragonal zirconia nanocrystallites was te...... exposure to humidity. Only silanes and phosphate esters of these were able to stabilize the tetragonal phase in water. Even as small amounts of silanes as 0.25 silane molecule per nm2 are able to stabilize the tetragonal phase in water at RT. Aminopropyl trimethoxy silane and γ...

Effect of tempering on corrosion resistance of cast aluminium bronzes

International Nuclear Information System (INIS)

Aaltonen, P.; Klemetti, K.; Haenninen, H.

1985-01-01

The subject of this study is corrosion resistance of aluminium bronzes, which are copper base alloys containing aluminium up to 12% with additions of nickel, iron and manganese. The main conclutions that can be drawn are: (1) The dealloying corrosion resistance of nickel-aluminium bronze is much better than that of aluminium bronze with iron and manganese additions, but it is not immune; (2) The dealloying corrosion resistance of aluminium bronzes can be improved by appropiate heat treatments. The best properties were obtained by temperering between 600 and 800 deg C, depending on the initial microstructure; (3) In crevice conditions, where local acidification can occur, dealloying of aluminium bronzes is a consequence of the preferential attack of aluminium-rich phases. By appropriate tempering, a uniform distribution of aluminium-rich phases is obtained and the continous path for selective corrosion is not formed

Origin of the mysterious Yin-Shang bronzes in China indicated by lead isotopes.

Science.gov (United States)

Sun, Wei-dong; Zhang, Li-peng; Guo, Jia; Li, Cong-ying; Jiang, Yu-hang; Zartman, Robert E; Zhang, Zhao-feng

2016-03-18

Fine Yin-Shang bronzes containing lead with puzzlingly highly radiogenic isotopic compositions appeared suddenly in the alluvial plain of the Yellow River around 1400 BC. The Tongkuangyu copper deposit in central China is known to have lead isotopic compositions even more radiogenic and scattered than those of the Yin-Shang bronzes. Most of the Yin-Shang bronzes are tin-copper alloys with high lead contents. The low lead and tin concentrations, together with the less radiogenic lead isotopes of bronzes in an ancient smelting site nearby, however, exclude Tongkuangyu as the sole supplier of the Yin-Shang bronzes. Interestingly, tin ingots/prills and bronzes found in Africa also have highly radiogenic lead isotopes, but it remains mysterious as to how such African bronzes may have been transported to China. Nevertheless, these African bronzes are the only bronzes outside China so far reported that have lead isotopes similar to those of the Yin-Shang bronzes. All these radiogenic lead isotopes plot along ~2.0-2.5 Ga isochron lines, implying that deposits around Archean cratons are the most likely candidates for the sources. African cratons along the Nile and even micro-cratons in the Sahara desert may have similar lead signatures. These places were probably accessible by ancient civilizations, and thus are the most favorable suppliers of the bronzes.

Setup of Galvanic Sensors for the Monitoring of Gilded Bronzes

Directory of Open Access Journals (Sweden)

Sara Goidanich

2014-04-01

Full Text Available Traditional electrochemical techniques, such as linear polarization resistance (Rp, and electrochemical impedance spectroscopy (EIS, cannot be applied to gilded bronzes, as it may not be possible to interpret the results obtained due to the bimetallic nature of the studied material. The measurement of the macrocouple current generated by the gold/bronze galvanic couple can be used as an indicator of degradation processes. Nevertheless, this measurement cannot be performed directly on the original artifacts due to the systematic presence of short-circuits between the two metals. In the present work the use of galvanic sensors is proposed as a possible solution for the monitoring of gilded bronze artefacts. The sensors have been designed to simulate real gilded bronze surfaces in terms of composition and stratigraphy and have proved to be a reliable diagnostic tool for the in situ monitoring of the rates of deterioration of gilded bronze surfaces and to test new conservation treatments. Their set-up and application is reported and their performances discussed.

Archaeological investigations of the Bronze Age village of Bagnara di Romagna (RA

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Maurizio Cattani

2014-12-01

Full Text Available This paper summarizes the results of researches carried out in the area next to the modern village of Bagnara di Romagna (RA, where several evidences related to a Bronze Age settlement have been collected. Recently test trenches and surface collections allowed to retrieve bronze and ceramics dating from the Middle Bronze Age (phase BM2 to the Recent Bronze Age (phase BR2. The analysis of landscape and the palaeoenvironmental reconstruction complete the outline of the region of Imola, Faenza and Lugo during the Bronze Age where are well known the ancient settlements of Solarolo, via Ordiere, Monte Castellaccio end S. Giuliano di Toscanella.

High-resolution angle-resolved photoemission investigation of potassium and phosphate tungsten bronzes

International Nuclear Information System (INIS)

Paul, Sanhita; Kumari, Spriha; Raj, Satyabrata

2016-01-01

Highlights: • Electronic structure of potassium and phosphate tungsten bronzes. • Origin of transport anomalies in bronzes. • Flat segments of Fermi surfaces are connected by a nesting vector, q. • Nesting driven charge-density wave is responsible for the anomalies. - Abstract: We have performed high-resolution angle-resolved photoemission spectroscopy (ARPES) and density functional ab initio theoretical calculation to study the electronic structure of potassium (K_0_._2_5WO_3) and phosphate (P_4W_1_2O_4_4) tungsten bronzes. We have experimentally determined the band dispersions and Fermi surface topology of these bronzes and compared with our theoretical calculations and a fair agreement has been seen between them. Our experimental as well as theoretical investigation elucidates the origin of transport anomalies in these bronzes. The Fermi surfaces of these bronzes consist of flat patches, which can be connected with each other by a constant nesting wave vector, q. The scattering wave vectors found from diffraction measurements match with these nesting vectors and the anomalies in the transport properties of these bronzes can be well explained by the evolution of charge-density wave with a partial nesting between the flat segments of the Fermi surfaces.

Synthesis and electrical conductivity of nanocrystalline tetragonal FeS

International Nuclear Information System (INIS)

Zeng Shu-Lin; Wang Hui-Xian; Dong Cheng

2014-01-01

A convenient method for synthesis of tetragonal FeS using iron powder as iron source, is reported. Nanocrystalline tetragonal FeS samples were successfully synthesized by reacting metallic iron powder with sodium sulfide in acetate buffer solution. The obtained sample is single-phase tetragonal FeS with lattice parameters a = 0.3767 nm and c = 0.5037 nm, as revealed by X-ray diffraction. The sample consists of flat nanosheets with lateral dimensions from 20 nm up to 200 nm and average thickness of about 20 nm. We found that tetragonal FeS is a fairly good conductor from the electrical resistivity measurement on a pellet of the nanosheets. The temperature dependence of conductivity of the pellet was well fitted using an empirical equation wherein the effect of different grain boundaries was taken into consideration. This study provides a convenient, economic way to synthesize tetragonal FeS in a large scale and reports the first electrical conductivity data for tetragonal FeS down to liquid helium temperature. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Manufacturing method of the bronze metallic filters

International Nuclear Information System (INIS)

Krivij, N.; Suwardjo, W.; Garcia, L.; Cores, A.; Formoso, A.

1997-01-01

Granulated (spherical) powders of bronze have been produced by spraying molten metal with gas at high pressure in the experimental industrial installation belonging to the Metallurgical Research Centre (CIME) in Havana City. A physical-chemical and technological characterisation of the spherical bronze powder has been carried out and the optimum parameters have been determined from these powders. The mechanical properties of these filters can satisfactorily rival in applications such as in motor transport goods, in industry and agriculture. (AUthor)

Metallography and microstructure interpretation of some archaeological tin bronze vessels from Iran

Energy Technology Data Exchange (ETDEWEB)

Oudbashi, Omid, E-mail: o.oudbashi@aui.ac.ir [Department of Conservation of Historic Properties, Faculty of Conservation, Art University of Isfahan, Hakim Nezami Street, Sangtarashha Alley, P.O. Box 1744, Isfahan (Iran, Islamic Republic of); Davami, Parviz, E-mail: pdavami@razi-foundation.com [Faculty of Material Science and Engineering, Sharif University of Technology/Razi Applied Science Foundation, No. 27, Fernan St., Shahid Ghasem Asghari Blvd., km 21 of Karadj Makhsous Road, Tehran (Iran, Islamic Republic of)

2014-11-15

Archaeological excavations in western Iran have recently revealed a significant Luristan Bronzes collection from Sangtarashan archaeological site. The site and its bronze collection are dated to Iron Age II/III of western Iran (10th–7th century BC) according to archaeological research. Alloy composition, microstructure and manufacturing technique of some sheet metal vessels are determined to reveal metallurgical processes in western Iran in the first millennium BC. Experimental analyses were carried out using Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy and Optical Microscopy/Metallography methods. The results allowed reconstructing the manufacturing process of bronze vessels in Luristan. It proved that the samples have been manufactured with a binary copper–tin alloy with a variable tin content that may relates to the application of an uncontrolled procedure to make bronze alloy (e.g. co-smelting or cementation). The presence of elongated copper sulphide inclusions showed probable use of copper sulphide ores for metal production and smelting. Based on metallographic studies, a cycle of cold working and annealing was used to shape the bronze vessels. - Highlights: • Sangtarashan vessels are made by variable Cu-Sn alloys with some impurities. • Various compositions occurred due to applying uncontrolled smelting methods. • The microstructure represents thermo-mechanical process to shape bronze vessels. • In one case, the annealing didn’t remove the eutectoid remaining from casting. • The characteristics of the bronzes are similar to other Iron Age Luristan Bronzes.

Synchrotron X-ray diffraction and imaging of ancient Chinese bronzes

International Nuclear Information System (INIS)

Young, M.L.; Dunand, D.C.; Casadio, F.; Schnepp, S.; Almer, J.; Haeffner, D.R.

2006-01-01

High-energy synchrotron X-ray diffraction and imaging experiments were performed at the Advanced Photon Source on two ancient Chinese bronzes from the Art Institute of Chicago with the goal to nondestructively study their microstructure. The first object, a bronze fragment from an early Western Zhou dynasty vessel (Hu, 11th/10th century B.C.), was investigated with spatially-resolved diffraction to reveal the depth and composition of the surface corrosion layer as well as the composition and grain size of the underlying bronze core. The second object, a bronze dagger-axe (Ge, 3rd/2nd century B.C.) with a silver-inlaid sheath, was studied under both diffraction and imaging conditions. It was found to have been cast as a single object, answering longstanding scholars' questions on whether the ceremonial object concealed an interior blade. (orig.)

Tetragonal-to-Tetragonal Phase Transition in Lead-Free (KxNa1−xNbO3 (x = 0.11 and 0.17 Crystals

Directory of Open Access Journals (Sweden)

Dabin Lin

2014-06-01

Full Text Available Lead free piezoelectric crystals of (KxNa1−xNbO3 (x = 0.11 and 0.17 have been grown by the modified Bridgman method. The structure and chemical composition of the obtained crystals were determined by X-ray diffraction (XRD and electron probe microanalysis (EPMA. The domain structure evolution with increasing temperature for (KxNa1−xNbO3 (x = 0.11 and 0.17 crystals was observed using polarized light microscopy (PLM, where distinguished changes of the domain structures were found to occur at 400 °C and 412 °C respectively, corresponding to the tetragonal to tetragonal phase transition temperatures. Dielectric measurements performed on (K0.11Na0.89NbO3 crystals exhibited tetragonal to tetragonal and tetragonal to cubic phase transitions temperatures at 405 °C and 496 °C, respectively.

Copper smelting and sediment pollution in Bronze Age China.

Science.gov (United States)

Zhang, S.; Dong, G.

2017-12-01

The emergence and diffusion of metallurgical technology had tremendous environmental consequence, however, the spatial-temporal consequences of the metallurgy during Bronze Age are not clear in China. Here, Xray fluorescence (XRF) measurement and principal component analysis (PCA) were conducted on heavy metal element (Cu, Ni, Pb, Zn, Cr and As) concentrations (HMEC) of natural and anthropogenic sediment samples systematically collected from 22 late Neolithic-Bronze Age sites in Hexi corridor to explore the potential for subcontinental-wide changes in soil geochemistry. We place this data within the context of the Cu concentrations in lacustrine sediments located near smelting and mining centers in Bronze Age China. Our results show that variation of HMEC in anthropogenic sediment in Hexi corridor is contemporaneous with the increases of the Cu concentrations in lacustrine sediment around 4000 BP. Comparative data suggests the metallurgical production diffused from the Hexi corridor to central and southwestern China around 3600 BP. We argue that sediment pollution is not an isolated phenomenon during the Bronze Age China, but rather occurred on regional scales and is closely related to the intensity of smelting activities.

Combined aging of beryllium bronze

International Nuclear Information System (INIS)

Duraev, P.P.; Kaplun, Yu.A.; Pastukhova, Zh.P.; Rakhshtadt, A.G.

1986-01-01

This article evaluates the possibility of increasing the resistance of beryllium bronze to small plastic deformations as a result of the application of stepped aging under stress. Low-temperature aging under conditions of bending under a stress of about 100 MPa was applied to alloy BrBNT1, 9Mg at 150, 180, and 210 0 C, high-temperature aging at 300 and 340 0 C under stress and without stress. As a result of applying stepped aging under stress, the elastic limit of the alloy BrBNT1, 9Mg was raised to 900 MPa. Stepped aging under stress has a substantial effect on the relaxation stability of the alloy. The procedure suggested in the article for aging may be used efficiently for treating elastic elements made of other brands of bronze as well

Prompt gamma-ray analysis of archaeological bronze

International Nuclear Information System (INIS)

Oura, Y.; Saito, A.; Sueki, K.; Nakahara, H.; Tomizawa, T.; Nishikawa, T.; Yonezawa, C.; Matsue, H.; Sawahata, H.

1999-01-01

Prompt γ-ray analysis using the internal monostandard method was applied to voluminous archaeological bronze mirrors produced in ancient China. Sn/Cu content ratios were determined nondestructively by this method. Furthermore, Au/Cu, As/Cu, and Sb/Cu content ratios were determined by means of measuring decay γ-rays emitted from radioactive nuclides produced within samples via (n,γ) reactions. It is clear that the Sn/Cu content ratios in bronze mirrors produced in the Sung era is smaller than in ones produced in between the Han and the Tung era. (author)

The Early-Middle bronze ages tombs from the Kartal fortress

Directory of Open Access Journals (Sweden)

Igor Bruiako

2017-09-01

Full Text Available The burials of Early- and Middle Bronze Age discovered by excavations of Kartal hill fort are analyzed in this article. One part of them belongs to the Pit-Grave Culture (later period, another – to the Culture Mnogovalikovaja. Allburials aresituated in the vicinity of ancient site, abandoned during the most part of the Bronze Age. The part of Pit-Grave burials representsflat/ pitgraves (non-kurgan. We assume that the seasonal settlement was located here in some periods of Bronze Age, while in the steppe of Eastern Europe dominated the populations of cattle-breeders.

An important harvest by applying Pb-isotope analysis to ancient Chinese bronzes

International Nuclear Information System (INIS)

Jin Zhengyao

2003-01-01

Analysing numerous ancient Chinese bronze objects unearthed at the archaeological sites by lead isotopic method, we found that a major portion Shang (1600 B. C.-1100 B. C.) bronzes contained a kind of high-radiogenic lead, The results suggested that there is a 'bronze road' linking the Shang sites in both of the Yellow River valley and the Yangtze River valley in Shang dynasty. (authors)

Glass ceramic toughened with tetragonal zirconia

Science.gov (United States)

Keefer, Keith D.; Michalske, Terry A.

1986-01-01

A phase transformation-toughened glass ceramic and a process for making it are disclosed. A mixture of particulate network-forming oxide, network-modifying oxide, and zirconium oxide is heated to yield a homogeneous melt, and this melt is then heat-treated to precipitate an appreciable quantity of tetragonal zirconia, which is retained at ambient temperature to form a phase transformation-toughened glass ceramic. Nucleating agents and stabilizing agents may be added to the mixture to facilitate processing and improve the ceramic's properties. Preferably, the mixture is first melted at a temperature from 1200.degree. to 1700.degree. C. and is then heat-treated at a temperature within the range of 800.degree. to 1200.degree. C. in order to precipitate tetragonal ZrO.sub.2. The composition, as well as the length and temperature of the heat-treatment, must be carefully controlled to prevent solution of the precipitated tetragonal zirconia and subsequent conversion to the monoclinic phase.

Abrasive wear of BA1055 bronze with additives of Si, Cr, Mo and/or W

Directory of Open Access Journals (Sweden)

B. P. Pisarek

2008-10-01

Full Text Available Aluminium bronzes belong to the high-grade constructional materials applied on the put under strongly load pieces of machines, aboutgood sliding, resistant properties on corrosion both in the cast state how and after the thermal processing. It moves to them Cr and Si in the aim of the improvement of their usable proprieties. The additions Mo and/or W were not applied so far. It was worked out therefore the new kind of bronzes casting including these elements. Make additions to the Cu-Al-Fe-Ni bronze of Si, Cr, Mo and/or W in the rise of these properties makes possible. The investigations of the surface distribution of the concentration of elements in the microstructure of the studied bronze on X-ray microanalyzer were conducted. It results from conducted investigations, that in the aluminium bronze BA1055 after makes additions Si, Cr, Mo and/or W the phases of the type κFe, κNi crystallize, probably as complex silicides. Elements such as: Fe and Si dissolve first of all in phases κ, in smaller stage in the matrix of the bronze; Mn, Ni and W they dissolve in matrix and phases κ. It dissolves Cr and Mo in the larger stage in phases κ than in the matrix. The sizes of the abrasive wear were compared in the state cast multicomponentnew casting Cu-Al-Fe-Ni bronzes with the additives Cr, Mo or W with the wear of the bronze CuAl10Fe5Ni5Si. The investigations of thewear were conducted on the standard device. It results from conducted investigations, that make additions to bronze BA1055 of the additives of Si, Cr, Mo, and/or W it influences the rise of the hardness (HB of the bronze in the cast state, in the result of the enlarged quantity separates of hard phases κ, and in the consequence the decrease of the abrasive wear. The addition of molybdenum made possible obtainment of the microhardness of the phase α and γ 2 on the comparable level. From the microstructure of the bronze CuAl10Fe5Ni5MoSi is characterizes the smallest abrasive wear among

Evaluation of some phenothiazine derivatives as corrosion inhibitors for bronze in weakly acidic solution

International Nuclear Information System (INIS)

Bostan, Roxana; Varvara, Simona; Găină, Luiza; Mureşan, Liana Maria

2012-01-01

Highlights: ► Phenothiazine derivatives are efficient inhibitors for bronze corrosion. ► Potentiodynamic polarization and EIS were used to elucidate inhibition mechanism. ► Adsorption of phenothiazine derivatives on bronze surface obeys Langmuir isotherm. ► A correlation between energy gaps and inhibition efficiencies values was obtained. - Abstract: Four phenothiazine derivatives have been tested as inhibitors for bronze corrosion in a solution containing Na 2 SO 4 and NaHCO 3 (pH 5). Electrochemical investigations (potentiodynamic polarisation and impedance measurements) revealed that all phenothiazine derivatives exert a protective effect against bronze corrosion and, in some cases their inhibition efficiency exceeds 90% at concentration level as low as 75 μM. An adherent layer of organic molecules chemisorbed on bronze surface is responsible for the protective effect of the investigated compounds. Adsorption of phenothiazine derivatives on bronze obeys Langmuir isotherm. Correlation between quantum chemical calculations and inhibition efficiency of the investigated compounds was discussed using DFT method.

Tetragonal and collapsed-tetragonal phases of CaFe2As2 : A view from angle-resolved photoemission and dynamical mean-field theory

Science.gov (United States)

van Roekeghem, Ambroise; Richard, Pierre; Shi, Xun; Wu, Shangfei; Zeng, Lingkun; Saparov, Bayrammurad; Ohtsubo, Yoshiyuki; Qian, Tian; Sefat, Athena S.; Biermann, Silke; Ding, Hong

2016-06-01

We present a study of the tetragonal to collapsed-tetragonal transition of CaFe2As2 using angle-resolved photoemission spectroscopy and dynamical mean field theory-based electronic structure calculations. We observe that the collapsed-tetragonal phase exhibits reduced correlations and a higher coherence temperature due to the stronger Fe-As hybridization. Furthermore, a comparison of measured photoemission spectra and theoretical spectral functions shows that momentum-dependent corrections to the density functional band structure are essential for the description of low-energy quasiparticle dispersions. We introduce those using the recently proposed combined "screened exchange + dynamical mean field theory" scheme.

Characterisation of a Proto-historic bronze collection by micro-EDXRF

International Nuclear Information System (INIS)

Figueiredo, Elin; Araújo, M. Fátima; Silva, Rui J.C.; Vilaça, Raquel

2013-01-01

Highlights: ► A collection of Proto-historic metal artefacts was analysed by micro-EDXRF. ► Composition of major and minor elements has been determined. ► Artefacts were manufactured in a bronze alloy with a low impurity pattern. ► The alloy shows parallels with indigenous Late Bronze Age Iberian productions. -- Abstract: Studies concerning European Proto-historic metallic artefacts can provide important clues about technological transfers during a period of time characterised by diverse cultural interactions. A collection of Proto-historic metallic artefacts from Medronhal (western Iberian Peninsula) composed by rings, bracelets and a fibula related to different cultural affiliations were investigated by micro-EDXRF to provide a major and a minor elemental characterisation. Results show that the Medronhal collection was manufactured in a Cu–Sn alloy (binary bronze) with similar Sn contents among the various types of artefacts and a low impurity pattern. Results of the type and quality of metal were compared to other artefact collections to infer about metallurgical parallels. Strong parallels with indigenous Late Bronze Age Iberian metallurgical productions were found

Characterisation of a Proto-historic bronze collection by micro-EDXRF

Energy Technology Data Exchange (ETDEWEB)

Figueiredo, Elin, E-mail: elin@itn.pt [IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Estrada Nacional 10, 2686-953 Sacavém (Portugal); CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Araújo, M. Fátima [IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, Estrada Nacional 10, 2686-953 Sacavém (Portugal); Silva, Rui J.C. [CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Vilaça, Raquel [CEAUCP-FCT, Instituto de Arqueologia, Departamento de História, Arqueologia e Artes, Faculdade de Letras, Universidade de Coimbra, Palácio de Sub-Ripas, 3000-395 Coimbra (Portugal)

2013-02-01

Highlights: ► A collection of Proto-historic metal artefacts was analysed by micro-EDXRF. ► Composition of major and minor elements has been determined. ► Artefacts were manufactured in a bronze alloy with a low impurity pattern. ► The alloy shows parallels with indigenous Late Bronze Age Iberian productions. -- Abstract: Studies concerning European Proto-historic metallic artefacts can provide important clues about technological transfers during a period of time characterised by diverse cultural interactions. A collection of Proto-historic metallic artefacts from Medronhal (western Iberian Peninsula) composed by rings, bracelets and a fibula related to different cultural affiliations were investigated by micro-EDXRF to provide a major and a minor elemental characterisation. Results show that the Medronhal collection was manufactured in a Cu–Sn alloy (binary bronze) with similar Sn contents among the various types of artefacts and a low impurity pattern. Results of the type and quality of metal were compared to other artefact collections to infer about metallurgical parallels. Strong parallels with indigenous Late Bronze Age Iberian metallurgical productions were found.

Non-destructive analysis of archaeological bronzes by nuclear techniques

International Nuclear Information System (INIS)

Respaldiza, M.A.; Gomez-Tubio, B.M.; Sanchez del Junco, A.; Barranco, F.; Saiz-Jimenez, C.

1994-01-01

This paper studies a method for overcoming the difficulty of corroded surfaces by means of nondestructive nuclear methods in the determination of the composition of archaeological bronzes. It consists of the combination of PIXE or XRF information with Gamma Ray Transmission (GRT) data. A wide range applicability of this combined method is established by comparison with profiles of concentrations along the bronzes' patina obtained by SEM-EDAX. (orig.)

Application of SIMS in patina studies on Bronze Age copper alloys

International Nuclear Information System (INIS)

Wouters, H.J.; Butaye, L.A.; Adams, F.C.

1992-01-01

The potential of secondary ion mass spectrometry for the patina studies on Bronze Age copper alloys is discussed. It is shown that the combined use of metallography, electron probe micro-analysis and ion microscopy can obtain very useful information concerning fabrication technology and corrosion mechanisms of ancient metals. Especially the convenience of measuring ion micrographs for relatively rapid qualitative indication of phases and inclusions, which are of interest for the investigation of different corroded surfaces found on ancient bronzes, is outlined. The results of investigated of two bronze objects with a specific patina appearance are presented. (orig.)

Characterization of corroded bronze Ding from the Yin Ruins of China

International Nuclear Information System (INIS)

Ling, He; Qingrong, Zhao; Min, Gao

2007-01-01

This paper presents the result of scientific examinations carried out on the soil-buried archaeological bronzes Ding from Yin Ruins of China. Eight of typical fragments from different bronze Ding were selected as researched samples according to their deterioration characteristics. Optical microscopy (OM), scanning electron microscopy coupled with energy (SEM-EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to understand the corrosive morphological characteristics, to clear the nature of patina and to analyze the elementary composition of bronze Ding. The results indicated that it is not possible to distinguish the original lustrous metallic surface in most samples because of the corrosive crust. The substrate of bronze Ding contains74-86% Cu, 1.1-4.6% Pb, and 10-18% Sn, which is in agreement with the historical investigation in the ritual vessels of Shang time. Copper-containing compounds were the main constituents of natural patina: Cu 2 (OH) 3 Cl existed as corrosion product in all the powdery or crack surface; Cu 2 (OH) 2 CO 3 was the main corrosive product in a compact and hard corrosive surface. This study provides useful information for the restoration and protection of bronze Ding in Yin Ruins

Characterization of metallic surfaces in phosphorous-bronze ordered packings

International Nuclear Information System (INIS)

Sandru, Claudia; Titescu, Gh.

1997-01-01

Copper and its alloys, particularly the phosphorous bronze, are characterized by a high water wettability as compared with other materials. This feature led to utilization of phosphorous bronze in fabrication of contact elements, a packing type equipping the distillation columns. For heavy water separation by isotopic distillation under vacuum, ordered packings of phosphorous bronze networks were fabricated. The superior performances of these packings are determined by the material and also by the geometrical form and the state of the metallic surface. Thus, a procedure of evaluating the wettability has been developed, based on tests of the network material. The results of the tests constitute a criterion of rating the functional performances of packings, particularly of their efficiencies. Also, investigation techniques of the chemical composition and of the thickness of superficial layer on the packing were developed. It was found that the packing surface presents a layer of about 5-20 μm formed mainly by oxides of copper, tin, and, depending on the packing treatment, of oxides of other elements coming from the treatment agent. The paper presents characterization of phosphorous bronze treated with potassium permanganate, a specific treatment for improving the functional performances of the packings used in the heavy water concentration and re-concentration installations

Impact of copper substitution on the structural, ferroelectric and magnetic properties of tungsten bronze ceramics

Science.gov (United States)

Jindal, Shilpi; Devi, Sheela; Batoo, Khalid Mujasam; Kumar, Gagan; Vasishth, Ajay

2018-05-01

The copper substituted tungsten bronze ceramics with generic formula Ba5CaCuXTi2-xNb8O30(x = 0.0, 0.02, 0.04, 0.06 and 0.08) were successfully synthesized for the first time by solid state reaction method. X-ray diffraction (XRD), Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) were utilized to examine the different structural parameters and elemental compositions. XRD study depicted the single phase tetragonal structure having space group P4bm. The crystallite size was observed to be in the range 14.4-30.23 nm. The coexistent of ferroelectricity and magnetism was established by P-E and M-H measurements. The P-E loop study indicated an increase in the coercive field (11.805-23.736 kVcm-1) while the M-H study depicted adecrease in the magnetization (7.65 × 10-4-5.32 × 10-4 emu/g) with the incorporation of Cu2+ ions. Raman spectrum depicted that there is shift in the position of Raman modes with the substitution of copper which revealed one-mode behavior in the synthesized ceramics.

Population genomics of Bronze Age Eurasia

Czech Academy of Sciences Publication Activity Database

Allentoft, M. E.; Sikora, M.; Sjogren, K.-G.; Rasmussen, S.; Rasmussen, M.; Stenderup, J.; Damgaard, P. B.; Schroeder, H.; Ahlström, T.; Vinner, L.; Malaspinas, A.-S.; Margaryan, A.; Higham, T.; Chivall, D.; Lynnerup, N.; Harvig, L.; Baron, J.; Della Casa, P.; Dabrowski, P.; Duffy, P. R.; Ebel, A. V.; Epimakhov, A.; Frei, K.; Furmanek, M.; Gralak, T.; Gromov, A.; Gronkiewicz, S.; Grupe, G.; Hajdu, T.; Jarysz, R.; Khartanovich, V.; Khokhlov, A.; Kiss, V.; Kolář, Jan; Kriiska, A.; Lasak, I.; Lonhgi, C.; McGlynn, G.; Merkevicius, A.; Merkyte, I.; Metspalu, M.; Mkrtchyan, R.; Moiseyev, V.; Paja, L.; Pilli, G.; Pokutta, D.; Pospieszny, L.; Price, D.; Saag, L.; Sablin, M.; Shishlina, N.; Smrčka, V.; Soenov, V. I.; Szeverenyi, V.; Tóth, G.; Trifanova, S. V.; Varul, L.; Vicze, M.; Yepiskoposyan, L.; Zhitenev, L.; Orlando, L.; Sicheritz-Ponten, T.; Brunak, S.; Nielsen, R.; Kristiansen, K.; Willerslev, E.

2015-01-01

Roč. 522, č. 7555 (2015), s. 167-172 ISSN 0028-0836 Institutional support: RVO:67985939 Keywords : genetics * migration * Bronze Age Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 38.138, year: 2015

Manipulation of polar order in the “empty” tetragonal tungsten bronzes: Ba{sub 4-x}Sr{sub x}Dy{sub 0.67}□{sub 1.33}Nb{sub 10}O{sub 30}, x = 0, 0.25, 0.5, 1, 2, 3

Energy Technology Data Exchange (ETDEWEB)

Gardner, Jonathan; Morrison, Finlay D., E-mail: finlay.morrison@st-andrews.ac.uk [EaStCHEM School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST (United Kingdom)

2016-08-15

A series of “empty” tetragonal tungsten bronze (TTB) ferroelectrics, Ba{sub 4-x}Sr{sub x}Dy{sub 0.67}□{sub 1.33}Nb{sub 10}O{sub 30} (x = 0, 0.25, 0.5, 1, 2, 3; □ = vacancy), is reported. With increasing x the unit cell contracts in both the ab plane and c-axis; x ≤ 1 compounds are normal ferroelectrics (FE) with decreasing T{sub C} as x increases, while x ≥ 2 are relaxor ferroelectrics (RFE) with associated frequency dependent permittivity peaks and with similar T{sub m} and T{sub f} (Vogel-Fulcher freezing temperatures) values. This observation is rationalised by differing cation occupancies: for x ≤ 1, Sr{sup 2+} principally occupies the A2-site (co-occupied by Ba{sup 2+} with the A1-site occupied by Dy{sup 3+} and vacancies); for x ≥ 2 significant Sr A1-site occupation leads to the observed RFE characteristics. This FE to RFE crossover is consistent with a previously proposed TTB crystal chemical framework where both a decrease in average A-site size and concurrent increase in A1-site tolerance factor (t{sub A1}) favour destabilization of long range polar order and relaxor behaviour. The effect of increasing t{sub A1} as a result of Sr occupancy at the A1 site is dominant in the compounds reported here.

Tetragonal to orthorhombic transformation in Mg-PSZ

International Nuclear Information System (INIS)

Liu, Z.W.; Spargo, A.E.C.; Hannink, R.H.J.; Drennan, J.

1997-01-01

The phase transformation from tetragonal to orthorhombic in MgO-partially-stabilized zirconia has been investigated by using high resolution transmission electron microscopy (HRTEM). Evidences are given to show that orthorhombic ZrO 2 frequently observed in transmission electron microscopy (TEM) thin foil studies was induced by dimpling and polishing during the specimen preparation. It was also found that the orthorhombic to monoclinic transformation was less sensitive to stress that the tetragonal to monoclinic transformation. 20 refs., 1 tab., 8 figs

Electrochemical Multi-Coloration of Molybdenum Oxide Bronzes

International Nuclear Information System (INIS)

Lee, Sangmin; Saji, Viswanathan S.; Lee, Chiwoo

2013-01-01

We report a simple electrochemical approach in fabricating multiple colored molybdenum (Mo) oxide bronzes on the surface of a Mo-quartz electrode. A three step electrochemical batch process consisting of linear sweep voltammetry and anodic oxidation followed by cathodic reduction in neutral K 2 SO 4 electrolyte at different end potentials, viz. -0.62, -0.80 and -1.60 V (vs. Hg/HgSO 4 ) yielded red, blue and yellow colored bronzes. The samples produced were analyzed by XRD, EDS, and SIMS. The color variation was suggested to be associated with the cations intercalation into the oxide formed and the simultaneous structural changes that occurred during the cathodic reduction in neutral aqueous medium

Electrochemical Multi-Coloration of Molybdenum Oxide Bronzes

Energy Technology Data Exchange (ETDEWEB)

Lee, Sangmin; Saji, Viswanathan S.; Lee, Chiwoo [Korea Univ., Seoul (Korea, Republic of)

2013-08-15

We report a simple electrochemical approach in fabricating multiple colored molybdenum (Mo) oxide bronzes on the surface of a Mo-quartz electrode. A three step electrochemical batch process consisting of linear sweep voltammetry and anodic oxidation followed by cathodic reduction in neutral K{sub 2}SO{sub 4} electrolyte at different end potentials, viz. -0.62, -0.80 and -1.60 V (vs. Hg/HgSO{sub 4}) yielded red, blue and yellow colored bronzes. The samples produced were analyzed by XRD, EDS, and SIMS. The color variation was suggested to be associated with the cations intercalation into the oxide formed and the simultaneous structural changes that occurred during the cathodic reduction in neutral aqueous medium.

Propolis as a green corrosion inhibitor for bronze in weakly acidic solution

Science.gov (United States)

Varvara, Simona; Bostan, Roxana; Bobis, Otilia; Găină, Luiza; Popa, Florin; Mena, Vicente; Souto, Ricardo M.

2017-12-01

In the present work, the inhibitive action of natural propolis on bronze corrosion in a weakly acidic solution containing Na2SO4 and NaHCO3 at pH 5 was evaluated using multiscale electrochemical techniques, namely potentiodynamic polarization, electrochemical impedance spectroscopy and scanning vibrating electrode technique measurements. The major constituents of propolis were identified by HPLC. Surface characterization was performed by SEM-EDX and AFM analysis. Experiments were performed as a function of the propolis concentration and immersion time in the corrosive electrolyte. The obtained results showed that propolis presents good anticorrosive properties on bronze, acting as a mixed-type inhibitor, but its protective effectiveness is time-dependent. The highest inhibiting efficiency of 98.9% was obtained in the presence of 100 ppm propolis, after about 12 h of exposure to inhibitor-containing electrolyte through the stabilization of Cu2O on the bronze surface. The inhibitive properties of propolis on bronze corrosion are likely due to the adsorption of its main constituents (flavonoids and phenolic compounds), through the oxygen atoms in their functional groups and aromatic rings, which have been evidenced by FT-IR spectra. The adsorption of propolis on bronze was found to follow Langmuir adsorption isotherm.

Portable XRF on Prehistoric Bronze Artefacts: Limitations and Use for the Detection of Bronze Age Metal Workshops

DEFF Research Database (Denmark)

Nørgaard, Heide Wrobel

2017-01-01

sections were analysed using a scanning electron microscope (SEM). Results from the corrosion crust of copper-tin alloys, and the change measured within the elemental composition from the bulk metal to the surface, greatly influenced the interpretation of the second data set, which was measured using......Two different scientific analyses—one destructive and one non destructive—were conducted on two separate groups of bronze ornaments dating from 1500–1100 BC to investigate, amongst other traits, the metal composition of their copper-tin alloys. One group of artefacts was sampled, and polished thin...... a handheld X-ray fluorescence (XRF) device. The surface of corroded bronze ornaments consists mostly of copper carbonates, oxides, and chlorides. Chemical processes, such as decuprification, change the element composition in such a manner that the original alloy cannot be traced with a non-destructive method...

Late Bronze Age hoard studied by PIXE

Energy Technology Data Exchange (ETDEWEB)

Gutierrez Neira, P.C., E-mail: carolina.gutierrez@uam.es [CMAM, Universidad Autonoma de Madrid, c/Farady 3, E-28049 Madrid (Spain); Zucchiatti, A., E-mail: alessandro.zucchiatti@uam.es [CMAM, Universidad Autonoma de Madrid, c/Farady 3, E-28049 Madrid (Spain); Montero-Ruiz, I., E-mail: ignacio.montero@cchs.csic.es [CCHS-CSIC, Albasanz 26-28, E 28037 Madrid (Spain); Vilaca, R., E-mail: rvilaca@fl.uc.pt [University of Coimbra, Largo da Porta Ferrea, 3000-447 Coimbra (Portugal); Bottaini, C., E-mail: keret18@yahoo.it [University of Coimbra, Largo da Porta Ferrea, 3000-447 Coimbra (Portugal); Gener, M., E-mail: marc.gener@cchs.csic.es [CCHS-CSIC, Albasanz 26-28, E 28037 Madrid (Spain); Climent-Font, A., E-mail: acf@uam.es [CMAM, Universidad Autonoma de Madrid, c/Farady 3, E-28049 Madrid (Spain); Department of Applied Physics, Universidad Autonoma de Madrid, Campus Cantobalanco, E-28049 Madrid (Spain)

2011-12-15

The hoards of metallic objects belonging to the Late European Bronze Age can be interpreted differently depending on the type, number and composition of the artefacts. PIXE analysis has been performed in nine items from the Hoard of Freixanda in Portugal comprising four socket axes, a palstave axe, a ring, a chisel, a dagger, and a casting debris. Besides the composition of the main matrix elements, that is Cu and Sn, the amount of trace elements of interest like, As, Pb, Ni, and Ag has been determined using this ion beam technique. The high tin content alloy and the high purity of the metals from the Freixanda hoard are characteristic of the Portuguese and Spanish Late Bronze Age metallurgy, supporting the idea of a regional production.

Ferroelastic domain switching in tetragonal zirconia

International Nuclear Information System (INIS)

Chan, C.J.; Ruhle, M.; Jue, J.F.; Virkar, A.V.

1991-01-01

Ferroelastic domain switching is one of the possible toughening mechanisms in ceramic materials. Microstructural evidence of domain reorientation (switching) in polydomain tetragonal zirconia single crystals is observed upon the application of a unidirectional compressive stress. Dark field imaging of the three (112) tetragonal twin variants in a [111] zone indicates that two sets of twin variants grow at the expense of the third set upon application of uniaxial compression. The diminishing variant is the one with its c axis parallel to the compression axis. Indentation experiments on uniaxially compressed samples show an anisotropy in crack length. Crack propogates more easily along the loading direction. In this paper construction for the orientation relationship of domains and their twin boundaries is presented

Corrosion of Bronzes by Extended Wetting with Single versus Mixed Acidic Pollutants

Directory of Open Access Journals (Sweden)

Liliana Gianni

2014-04-01

Full Text Available The corrosion of bronzes was examined in the context of single-acid versus mixed-acid (as in urban acid rain solutions. Two bi-component bronzes (copper with either 3% Sn or 7% Sn that closely represent those of historic artifacts were immersed for five weeks in conditions designed to replicate those experienced by statues and ornaments in cities where rainfall and humidity constantly produce an electrolyte layer on the surfaces of bronzes. Ions, acids, and particles of pollutants can dissolve in this layer, resulting in a variety of harsh corrosion processes. The kinetics of corrosion and the properties of the resulting patinas were monitored weekly by electrochemical impedance spectroscopy and open-circuit potential measurements. The sizes and appearances of the corrosion products were monitored and used to estimate the progress of the corrosion, whose crystalline structures were visualized using scanning electron microscopy with energy dispersive spectroscopy, identified by X-ray diffraction, and characterized by spectrocolorimetry. The electrochemical measurements demonstrated that greater damage (in terms of color change and corrosion product formation did not correspond to deficiencies in protection. The mixed-acid solution did not corrode the bronzes, as would be expected from the additive effects of the single acids. The postulated mechanisms of metal dissolution appear to be specific to a particular bronze alloy, with the tin component playing an important role.

Production and properties of bronze based cellular materials

International Nuclear Information System (INIS)

Strobl, S.; Danninger, H.

2001-01-01

For production of lightweight components, cellular materials offer attractive potential. Here, manufacturing of sintered bodies from bronze hollow spheres is described. The process starts with fabrication of hollow copper particles by cementation of Cu on iron particles. The still fragile Cu shells are consolidated by coating with Sn and subsequent gravity sintering. The resulting specimens exhibit a closed cell bronze structure with rather consistent morphology and cell wall thickness. The apparent density may range between 1.5 and 3.0 gcm -3 and can be controlled by variation of particle size and wall thickness. The mechanical behavior of the structures esp. during compressive loading is described and related to the microstructural parameters. (author)

Ferroelectric properties of tungsten bronze morphotropic phase boundary systems

International Nuclear Information System (INIS)

Oliver, J.R.; Neurgaonkar, R.R.; Cross, L.E.; Pennsylvania State Univ., University Park, PA

1989-01-01

Tungsten bronze ferroelectrics which have a morphotropic phase boundary (MPB) can have a number or enhanced dielectric, piezoelectric, and electrooptic properties compared to more conventional ferroelectric materials. The structural and ferroelectric properties of several MPB bronze systems are presented, including data from sintered and hot-pressed ceramics, epitaxial thin films, and bulk single crystals. Included among these are three systems which had not been previously identified as morphotropic. The potential advantages and limitations of these MPB systems are discussed, along with considerations of the appropriate growth methods for their possible utilization in optical, piezoelectric, or pyroelectric device applications

Antibacterial drugs as corrosion inhibitors for bronze surfaces in acidic solutions

Energy Technology Data Exchange (ETDEWEB)

Rotaru, Ileana [Department of Chemical Engineering, “Babes-Bolyai” University, 11 Arany-Janos St., 400028 Cluj-Napoca (Romania); Varvara, Simona, E-mail: svarvara@uab.ro [Department of Exact Sciences and Engineering, “1 Decembrie 1918” University, 11-13 Nicolae Iorga St., 510009 Alba Iulia (Romania); Gaina, Luiza [Department of Chemical Engineering, “Babes-Bolyai” University, 11 Arany-Janos St., 400028 Cluj-Napoca (Romania); Muresan, Liana Maria, E-mail: limur@chem.ubbcluj.ro [Department of Chemical Engineering, “Babes-Bolyai” University, 11 Arany-Janos St., 400028 Cluj-Napoca (Romania)

2014-12-01

Graphical abstract: - Highlights: • All four investigated antibacterial drugs act as corrosion inhibitors for bronze surface. • In the presence of antibiotics, a 3RC electric circuit simulates the corrosion system. • The electrochemical results indicate as best inhibitors Doxy, followed by Strepto. • HOMO–LUMO energy gap increases in the order: Doxy > Strepto > Cipro > Amoxi. • The thin protective film on bronze is reinforced by the presence of the antibiotics. - Abstract: The present study is aiming to investigate the effect of four antibiotics (amoxicillin, ciprofloxacin, doxycycline and streptomycin,) belonging to different classes of antibacterial drugs on bronze corrosion in a solution simulating an acid rain (pH 4). Due to their ability to form protective films on the metal surface, the tested antibiotics act as corrosion inhibitors for bronze. The antibiotics were tested at various concentrations in order to determine the optimal concentration range for the best corrosion inhibiting effect. In evaluating the inhibition efficiency, polarization curves, electrochemical impedance spectroscopy, SEM and XPS measurements were used. Moreover, a correlation between the inhibition efficiency of some antibacterial drugs and certain molecular parameters was determined by quantum chemical computations. Parameters like energies E{sub HOMO} and E{sub LUMO} and HOMO–LUMO energy gap were used for correlation with the corrosion data.

Antibacterial drugs as corrosion inhibitors for bronze surfaces in acidic solutions

International Nuclear Information System (INIS)

Rotaru, Ileana; Varvara, Simona; Gaina, Luiza; Muresan, Liana Maria

2014-01-01

Graphical abstract: - Highlights: • All four investigated antibacterial drugs act as corrosion inhibitors for bronze surface. • In the presence of antibiotics, a 3RC electric circuit simulates the corrosion system. • The electrochemical results indicate as best inhibitors Doxy, followed by Strepto. • HOMO–LUMO energy gap increases in the order: Doxy > Strepto > Cipro > Amoxi. • The thin protective film on bronze is reinforced by the presence of the antibiotics. - Abstract: The present study is aiming to investigate the effect of four antibiotics (amoxicillin, ciprofloxacin, doxycycline and streptomycin,) belonging to different classes of antibacterial drugs on bronze corrosion in a solution simulating an acid rain (pH 4). Due to their ability to form protective films on the metal surface, the tested antibiotics act as corrosion inhibitors for bronze. The antibiotics were tested at various concentrations in order to determine the optimal concentration range for the best corrosion inhibiting effect. In evaluating the inhibition efficiency, polarization curves, electrochemical impedance spectroscopy, SEM and XPS measurements were used. Moreover, a correlation between the inhibition efficiency of some antibacterial drugs and certain molecular parameters was determined by quantum chemical computations. Parameters like energies E HOMO and E LUMO and HOMO–LUMO energy gap were used for correlation with the corrosion data

Clay Corner: Recreating Chinese Bronze Vessels.

Science.gov (United States)

Gamble, Harriet

1998-01-01

Presents a lesson where students make faux Chinese bronze vessels through slab or coil clay construction after they learn about the history, function, and design of these vessels. Utilizes a variety of glaze finishes in order to give the vessels an aged look. Gives detailed guidelines for creating the vessels. (CMK)

21 CFR 73.1646 - Bronze powder.

Science.gov (United States)

2010-04-01

... percent. Maximum particle size 45µ (95 percent minimum). Aluminum, zinc, tin, and copper content shall be based on the weight of the dried powder after being thoroughly washed with ether. (c) Uses and restrictions. Bronze powder may be safely used in color externally applied drugs, including those intended for...

Lead isotope approach to the understanding of early Japanese bronze culture

International Nuclear Information System (INIS)

Mabuchi, H.; Hirao, Y.

1985-01-01

For several years, the authors have used lead isotope analysis to investigate extensively the provenance of ancient bronze or copper artifacts which had been excavated mainly from Japanese archaeological sites. The results have been published item by item in several relevant Japanese journals. This review is intended to give an account which will review the whole work relating early Japanese bronze culture to Chinese and Korean cultures through lead isotope study. (author)

75 FR 57825 - Culturally Significant Objects Imported for Exhibition Determinations: “Ancient Chinese Bronzes...

Science.gov (United States)

2010-09-22

... DEPARTMENT OF STATE [Public Notice 7181] Culturally Significant Objects Imported for Exhibition Determinations: ``Ancient Chinese Bronzes From the Shouyang Studio: The Katherine and George Fan Collection... ``Ancient Chinese Bronzes from the Shouyang Studio: The Katherine and George Fan Collection,'' imported from...

Investigations on dry sliding of laser cladded aluminum bronze

Directory of Open Access Journals (Sweden)

Freiße Hannes

2016-01-01

Full Text Available The aim of this study was to investigate the tribological behaviour of laser cladded aluminum bronze tool surfaces for dry metal forming. In a first part of this work a process window for cladding aluminum bronze on steel substrate was investigated to ensure a low dilution. Therefore, the cladding speed, the powder feed rate, the laser power and the distance between the process head and the substrate were varied. The target of the second part was to investigate the influence of different process parameters on the tribological behaviour of the cladded tracks. The laser claddings were carried out on both aluminum bronze and cold work tool steel as substrate materials. Two different particle sizes of the cladding powder material were used. The cladding speed was varied and a post-processing laser remelting treatment was applied. It is shown that the tribological behaviour of the surface in a dry oscillating ball-on-plate test is highly dependent on the substrate material. In the third part a deep drawing tool was additively manufactured by direct laser deposition. Furthermore, the tool was applied to form circular cups with and without lubrication.

Characterisation of Late Bronze Age large size shield nails by EDXRF, micro-EDXRF and X-ray digital radiography

International Nuclear Information System (INIS)

Figueiredo, E.; Araujo, M.F.; Silva, R.J.C.; Senna-Martinez, J.C.; Ines Vaz, J.L.

2011-01-01

In the present study six exceptional large size metallic nails, a dagger and a sickle from the Late Bronze Age archaeological site of Figueiredo das Donas (Central Portugal) have been analysed by EDXRF, micro-EDXRF and X-ray digital radiography for the study of material composition and technology of fabrication. The combination of these analytical and examination techniques showed that all artefacts are made of bronze with As, Sb and Pb impurities, and that the nails were most likely manufactured using the casting-on technique. These results reinforce the use of binary bronze by Late Bronze Age in the region, and the incorporation of new fabrication technologies that resulted from ancient spheres of interaction. - Highlights: → EDXRF, micro-EDXRF and X-ray digital radiography in cultural heritage studies. → Archaeometallurgical study of a Late Bronze Age artefact collection from Portugal. → Practise of a specific and traditional bronze metallurgy. → Appearance of technological innovations as the casting-on technique.

ISOTOPES, PLANTS, AND RESERVOIR EFFECTS : CASE STUDY FROM THE CASPIAN STEPPE BRONZE AGE

NARCIS (Netherlands)

Shishlina, N.; Zazovskaya, E.; van der Plicht, J.; Sevastyanov, V.; Boaretto, E.; Rebollo Franco, N.R.

2012-01-01

Bronze Age human and animal bone collagen from several steppe Bronze Age cultures (i.e. Early Catacomb, East and West Manych Catacomb, and Lola cultures) shows large variations in delta C-13 and delta N-15 values. In general, we observed that the older the sample, the lower the delta C-13 and delta

Portable EDXRF investigation of the patinas on the Riace Bronzes

Energy Technology Data Exchange (ETDEWEB)

Buccolieri, Giovanni, E-mail: giovanni.buccolieri@unisalento.it [Università del Salento, Dipartimento di Matematica e Fisica, via Arnesano, 73100 Lecce (Italy); Buccolieri, Alessandro, E-mail: alessandro.buccolieri@unisalento.it [Università del Salento, Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, via Monteroni, 73100 Lecce (Italy); Donati, Paola, E-mail: paola.donati@beniculturali.it [Istituto Superiore per la Conservazione e il Restauro, via di San Michele n. 23, 00153 Roma (Italy); Marabelli, Maurizio, E-mail: maurizio.marabelli@libero.it [Istituto Superiore per la Conservazione e il Restauro, via di San Michele n. 23, 00153 Roma (Italy); Castellano, Alfredo, E-mail: alfredo.castellano@unisalento.it [Università del Salento, Dipartimento di Matematica e Fisica, via Arnesano, 73100 Lecce (Italy)

2015-01-15

This paper summarizes the experimental results concerning the Energy Dispersive X-ray Fluorescence (EDXRF) analysis of patinas on two Riace Bronzes, kept in the National Archaeological Museum of Reggio Calabria (Calabria, Southern Italy). The two large Greek sculptures, famous nude bearded warriors both dated in the fifth century BC, are without a doubt, two masterpieces of inestimable historic and artistic value. EDXRF survey had the aim to determinate the chemical composition of the surface of these two bronze statues and to discriminate their different patinas. In particular, the concentration of sulphur, chlorine, tin, manganese, iron, copper, zinc and lead was determined by using a portable apparatus. Multivariate statistical analysis was carried out in order to identify possible correlations and/or differences of elemental composition among the patinas of these two statues. The information obtained made it possible to improve knowledge about the patinas of the Riace Bronzes, and this may help further studies and subsequent methods of restoration and/or of preservation of the two celebrated Greek sculptures.

Structural study on cubic-tetragonal transition of CH3NH3PbI3

International Nuclear Information System (INIS)

Kawamura, Yukihiko; Mashiyama, Hiroyuki; Hasebe, Katsuhiko

2002-01-01

The cubic-tetragonal phase transition of CH 3 NH 3 PbI 3 was investigated by single crystal X-ray diffractometry. The crystal structure was refined at five temperatures in the tetragonal phase. The PbI 6 octahedron rotates around the c-axis alternatively to construct the SrTiO 3 -type tetragonal structure. A methylammonium ion is partially ordered; 24 disordered states in the cubic phase are reduced to 8. With decreasing temperature, the rotation angle of the octahedron increases monotonically, which indicates it is an order parameter of the cubic-tetragonal transition. (author)

Dating simple flakes: Early Bronze Age flake production technology on the Middle Euphrates Steppe, Syria

Directory of Open Access Journals (Sweden)

Yoshihiro Nishiaki

2014-03-01

Full Text Available Aceramic flint scatters, comprising very crude cores or flakes and no formalised tools, are frequently found on the Middle Euphrates steppe of northern Syria. Previous studies suggest that many of them are residues of short-term activities by the nomads or shepherds of the Early Bronze Age. In order to verify this interpretation, a more precise chronological framework needs to be established for the Early Bronze Age lithic industry. This paper analyses stratified flake assemblages of the Early Bronze Age at Tell Ghanem al-Ali, a securely radiocarbon-dated settlement on the Middle Euphrates, and examines which occupation level yields assemblages most similar to those of the steppe. Results demonstrate that the lithic industry of this period underwent significant diachronic changes in terms of core reduction technology. Based on the chronological framework developed at Tell Ghanem al-Ali, the steppe assemblages in question can be assigned to different phases of the Early Bronze Age. This finding will help identify processes at the beginning of the extensive exploitation of the steppe, which is regarded as one of the most important socioeconomic changes that occurred among Early Bronze Age communities of the Middle Euphrates.

Izumo and the East Asian Bronze Culture%出云与东亚的青铜文化

Institute of Scientific and Technical Information of China (English)

王巍

2003-01-01

The origin of bronzes in Yayoi Japan can be traced to their counterparts in Xia-Shang-Zhou China. It must have happened that ancient Chinese bronze weapons and small bells used aspractical implements were first spread into Japan through northeastern China and the Korean Peninsulaand then developed gradually into bronzes exclusively for sacrificial use. Among the bronzes unearthed inbatches from hoards in the Izumo area within the coastland of the Sea of Japan, the spearheads may havebeen made in the north of Kyushu, the small bells must have come from the Kinai region, and the over300 swords were probably local products. The repeated discovery of Yayoi bronze hoards in the Izumoarea suggests that this region was absolutely not an unpopulated land. On the contrary, as a very im-portant district, it should be fully affirmed to have played a considerable role in the development of an-cient Japanese history.

Tribaloy alloy reinforced tin-bronze composite coating for journal bearing applications

International Nuclear Information System (INIS)

Gao, F.; Liu, R.; Wu, X.J.

2011-01-01

This article presents an experimental study of the tribological behavior of a tin/bronze-based composite coating. The improved-ductility Tribaloy alloy (T-401) particles are selected as the reinforcement. This coating is made on the bushing of planet journals used in aerospace engines, deposited with the high velocity oxygen fuel (HVOF) thermal spray technique. The tribological properties such as friction and wear resistance of the coated bushing are investigated under the WAMsc3 Sliding Contact Test, along with the leaded tin/bronze bushing tested for comparison. The testing results show that the bushing coated with the composite exhibits superior tribological properties to the leaded tin/bronze bushing in that the former runs longer before the friction coefficient reaches 0.5 and also leads a to lower wear rate than the latter. The experimental results and wear mechanisms of these two bushings are discussed with the assistance of worn surface analyses using scanning electron microscopy (SEM).

Boiling heat transfer on single phosphor bronze and copper mesh microstructures

Directory of Open Access Journals (Sweden)

Orman Łukasz J.

2014-03-01

Full Text Available The paper presents experimental results of boiling heat transfer of distilled water and ethyl alcohol on surfaces covered with single layers of wire mesh structures made of phosphor bronze and copper. For each material two kinds of structures have been considered (higher and lower in order to determine the impact of the height of the structure on boiling heat transfer. The wire diameter of the copper meshes was 0,25 mm and 0,32 mm, while of the bronze meshes: 0,20 mm and 0,25 mm. The structures had the same mesh aperture (distance between the wires – 0,50 mm for copper and 0,40 for bronze but different wire diameter and, consequently, different height of the layers. The tests have been performed under ambient pressure in the pool boiling mode. The obtained results indicate a visible impact of the layer height on the boiling heat transfer performance of the analysed microstructures.

Influence of Metal-Coated Graphite Powders on Microstructure and Properties of the Bronze-Matrix/Graphite Composites

Science.gov (United States)

Zhao, Jian-hua; Li, Pu; Tang, Qi; Zhang, Yan-qing; He, Jian-sheng; He, Ke

2017-02-01

In this study, the bronze-matrix/x-graphite (x = 0, 1, 3 and 5%) composites were fabricated by powder metallurgy route by using Cu-coated graphite, Ni-coated graphite and pure graphite, respectively. The microstructure, mechanical properties and corrosive behaviors of bronze/Cu-coated-graphite (BCG), bronze/Ni-coated-graphite (BNG) and bronze/pure-graphite (BPG) were characterized and investigated. Results show that the Cu-coated and Ni-coated graphite could definitely increase the bonding quality between the bronze matrix and graphite. In general, with the increase in graphite content in bronze-matrix/graphite composites, the friction coefficients, ultimate density and wear rates of BPG, BCG and BNG composites all went down. However, the Vickers microhardness of the BNG composite would increase as the graphite content increased, which was contrary to the BPG and BCG composites. When the graphite content was 3%, the friction coefficient of BNG composite was more stable than that of BCG and BPG composites, indicating that BNG composite had a better tribological performance than the others. Under all the values of applied loads (10, 20, 40 and 60N), the BCG and BNG composites exhibited a lower wear rate than BPG composite. What is more, the existence of nickel in graphite powders could effectively improve the corrosion resistance of the BNG composite.

Study on surface properties of gilt-bronze artifacts, after Nd:YAG laser cleaning

Energy Technology Data Exchange (ETDEWEB)

Lee, Hyeyoun [Division of Restoration Technology, National Research Institute of Cultural Heritage, Daejeon (Korea, Republic of); Cho, Namchul, E-mail: nam1611@hanmail.net [Department of Cultural Heritage Conservation Science, Kongju National University, Gongju, 314-701 (Korea, Republic of); Lee, Jongmyoung [Laser Engineering Group, IMT Co. Ltd, Gyeonggi (Korea, Republic of)

2013-11-01

As numerous pores are formed at plating gilt-bronze artifacts, the metal underlying the gold is corroded and corrosion products are formed on layer of gold. Through this study, the surfaces of gilt-bronze are being investigated before and after the laser irradiation to remove corrosion products of copper by using Nd:YAG laser. For gilt-bronze specimens, laser and chemical cleaning were performed, and thereafter, surface analysis with SEM-EDS, AFM, and XPS were used to determine the surface characteristics. Experimental results show that chemical cleaning removes corrosion products of copper through dissolution but it was not removed uniformly and separated the metal substrate and the gold layer. Nevertheless, through laser cleaning, some of the corrosions were removed with some damaged areas due to certain conditions and brown residues remained. Brown residues were copper corrosion products mixed with soil left within the gilt layer. It was due to surface morphology of uneven and rough gilt layer. Hence, they did not react effectively to laser beams, and thus, remained as residues. The surface properties of gilt-bronze should be thoroughly investigated with various surface analyses to succeed in laser cleaning without damages or residues.

Degradation measurement of bronzes, a recent application of the TLA techniques in the field of cultural heritage

International Nuclear Information System (INIS)

Danesi, P.R.; Laguzzi, G.; Luvidi, L

2001-01-01

The thin layer technique is normally applied in wear and corrosion monitoring of mechanical and plant components. A recent applications refers to the field of Cultural Heritage. In particular thought national and international research programmes TLA is used as a sensitivity toll in determining the properties towards corrosion of new bronze alloys to be used for artistic purposes, as in manufacturing of outdoor artworks. One activated and exposed to natural or artificial corrosive environments the bronze surface is treated with pick ling solutions to remove the corrosion products, The corresponding thickness loss is determined by the relevant γ-activity loss. The method sensitivity allows of the thickness loss evaluation in the order micrometers of lower. Besides comparative analyses of the behaviour of different bronze alloys, this method is also applied in determining the effectiveness of corrosion inhibitor or protective films, normally used on outdoor bronze sculptures. The metal activation is carried out by using a cyclotron accelerated proton beam (11.5 MeV) which products on the bronze surface and along a defined depth γemitting radionuclide 65 Zn (t 1/2 = 244 days). In the present paper, bronze corrosion results obtained in different environmental conditions as outdoor exposures and artificial weathering experiments are reported

Cloth cultures in prehistoric Europe: the Bronze Age evidence from Hallstatt

Directory of Open Access Journals (Sweden)

Susanna Harris

2009-09-01

Full Text Available Cloth Cultures in Prehistoric Europe is a Postdoctoral Fellowship project awarded to Susanna Harris by the British Academy. Its aim is to bring together and examine evidence for textiles and animal skins in prehistoric Europe from the Neolithic and Bronze Age. Several case studies are being examined as part of this project, including the Bronze Age Hallstatt salt mines. Here researchers working on the materials from Hallstatt look at some of the similarities and differences between the techniques applied to textiles and animal skins in their production and use in the mines.

Glycerol oxidehydration into acrolein and acrylic acid over W/V/Nb bronzes with hexagonal structure

Energy Technology Data Exchange (ETDEWEB)

Basile, F.; Cavani, F.; Chieregato, A. [Bologna Univ. (Italy). Dipt. di Chimica Industriale e dei Materiali; CIRI Energia e Ambiente, Bologna (Italy); Concepcion, P.; Lopez Nieto, J.M.; Soriano, M.D. [Univ. Politecnica de Valencia (Spain). Inst. de Tecnologia Quimica; Liosi, G.; Trevisanut, C. [Bologna Univ. (Italy). Dipt. di Chimica Industriale e dei Materiali

2012-07-01

This paper deals with an investigation of hexagonal W-V-Nb-O and W-V-Mo-O bronzes as catalysts for the one-pot oxidehydration of glycerol into acrylic acid. In a previous work, we reported a study on a bi-component bronze W-V-O that allowed us to obtain a 25% acrylic acid selectivity; in the current work, the incorporation of either Nb or Mo in a tri-component bronze structure allowed us to tune the acid and redox properties of the catalyst, so as to study their influence on the overall reaction scheme. (orig.)

Bronze railing from Mediana

Directory of Open Access Journals (Sweden)

Vasić Miloje R.

2003-01-01

Full Text Available The hoard containing components of bronze railing was discovered in trench 7 during excavations at Mediana in 2000. Railing consists of cancelli and herms with busts of deities between them. Railing was constructed in such a way that it was possible to disassemble and reassemble it. Three cancelli one fragmented semicancellus cast together with herm and herms, one with bust of Aesculapius and other with bust of Luna. It could be concluded that railing consisted of two segments with passage between them. Male deities were represented on the left segment of the railing and female deities on the right segment. Detailed analysis revealed that Aesculapius as well as Luna bear strong mark of classical Greek and Hellenistic art, which experienced some kind of renaissance in the time of Constantine I. It is very probable that we can recognize the portrait of Faustina, Constantine’s wife in the portrait of Luna. According to the historical events the railing could have been produced before 325 AD when Constantine definitively accepted Christianity at Council of Nicaea. It is difficult to say where the railing had been produced. It had been most probably brought to Mediana during the stay of emperor Julian in Niš in 361. The sculptures found in one room of the villa with peristyle had probably been brought at the same time. The apse of triclinium of this villa had most likely been arranged as small shrine with bronze railing at its entrance. The railing was buried in 378 after battle of Adrianople and invasion of Goths in diocese Dacia.

Electrodeposited nanocrystalline bronze alloys as replacement for Ni

NARCIS (Netherlands)

Hovestad, A.; Tacken, R.A.; Mannetje, H.H.'t

2008-01-01

Nanocrystalline white-bronze, CuSn, electroplating was investigated as alternative to Ni plating as undercoat for noble metals in jewellery applications. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. Polarization

Study of wear mechanism of chopped fiber reinforced epoxy composite filled with graphite and bronze

Science.gov (United States)

Patil, Nitinchand; Prasad, Krishna

2018-04-01

The combined effect of graphite and sintered bronze with a short glass fiber reinforced epoxy composites was investigated in this work. A pin on disc wear test was carried out to study the wear behaviour and mechanism of the composites. The objective of this work is to develop an alternate friction resistance material for the application of sliding bearing. It was observed that the addition of sintered bronze improved mechanical and thermal stability of the composites as bronze has low contact resistance with graphite and has high thermal conductivity. It was observed from the test results that increased volume percentage of graphite and presence of bronze are play significant role in wear mechanism of the composites. It was observed from the scanning electronic microscopes (SEM) that the abrasive and adhesive wear mechanism was prominent in this study. It was also evident from the result that the frictional force remains stable irrespective of the applied normal load.

Haute Couture in the Bronze Age: A History of Minoan Female Costumes from Thera

DEFF Research Database (Denmark)

Nosch, Marie-Louise Bech

2008-01-01

Haute Couture in the Bronze Age from Thera is investigated via frescoes and with a historiographical approach on the reception of Minoan culture in contemporary Greek history......Haute Couture in the Bronze Age from Thera is investigated via frescoes and with a historiographical approach on the reception of Minoan culture in contemporary Greek history...

75 FR 15764 - Culturally Significant Objects Imported for Exhibition Determinations: “Gods of Angkor: Bronzes...

Science.gov (United States)

2010-03-30

... Determinations: ``Gods of Angkor: Bronzes From the National Museum of Cambodia'' SUMMARY: Notice is hereby given... objects to be included in the exhibition ``Gods of Angkor: Bronzes from the National Museum of Cambodia,'' imported from abroad for temporary exhibition within the United States, are of cultural significance. The...

Understanding metal–insulator transition in sodium tungsten bronze

Indian Academy of Sciences (India)

2015-05-20

May 20, 2015 ... We have carried out angle-resolved photoemission spectroscopy (ARPES) and spectromicroscopy studies to understand the metal–insulator transition (MIT) observed in sodium tungsten bronzes, NaWO3. The experimentally determined band structure is compared with the theoretical calculation based ...

Comparative Investigations on the Stress Corrosion Behavior of α -Al Bronze and α Brass in Sodium Nitrite

International Nuclear Information System (INIS)

Ashour, E.A.

1995-01-01

The stress corrosion behavior of α- Aluminum bronze (copper [Cu] -7% Al) (UNS C 61400) has been investigated as compared to α- brass under slow strain in sodium nitrite solutions under open - circuit and different anodic potentials. While α- brass was quite susceptible to SCC, α- Al bronze was found to be resistant to SCC. The ratios of time to failure in solution to that in air and of maximum stress in solution to that in air decreased sharply with increase of anodic potential for α-brass but remained virtually constant for α- Al bronze. The mode of failure was predominantly ductile for α- Al bronze under various conditions. The stress corrosion cracking of α - brass has been shown to be promoted by relatively concentrated Na N O 2 and high anodic potentials. Previous explanations for the change of the mode of failure from intergranular at open circuit potential (OCP) to transgranular cracking under anodic potential were confirmed. The bronzes resistance to SCC was attributed to the presence of Al 2 O 3 on the alloy surface. 10 Figs

Lattice vibrations and cubic to tetragonal phase transition in ZrO2

International Nuclear Information System (INIS)

Negita, K.

1989-01-01

On the basis of analyses of phonon modes in ZrO 2 , it is suggested that condensation of a phonon X 2 - at the cubic Brillouin zone boundary X point, (0, 0, 2 π/a), is associated with the cubic to tetragonal phase transition in ZrO 2 . Free energy consideration shows that spontaneous volume and shear strains, e Alg = (e 1 +e 2 +e 3 ) and e Eg = (2e 3 - e 1 - e 2 )/ Λ3, are induced in the tetragonal phase as a result of indirect couplings of the X 2 - mode to homogeneous elastic strains; the tetragonal phase is improper ferroelastic

A comprehensive investigation of tetragonal Gd-doped BiVO{sub 4} with enhanced photocatalytic performance under sun-light

Energy Technology Data Exchange (ETDEWEB)

Luo, Yangyang; Tan, Guoqiang, E-mail: tan3114@163.com; Dong, Guohua; Ren, Huijun; Xia, Ao

2016-02-28

Graphical abstract: - Highlights: • Tetragonal Gd-BiVO{sub 4} with enhanced photocatalytic activity was synthesized. • Gd doping can induce the phase transition from monoclinic to tetragonal BiVO{sub 4}. • GdVO{sub 4} seeds as crystal nucleus dominate the formation of tetragonal Gd-BiVO{sub 4}. • Tetragonal Gd-BiVO{sub 4} exhibits the excellent separation of electrons and holes. • The contribution of high photocatalytic activity under sun-light is from UV-light. - Abstract: Tetragonal Gd-doped BiVO{sub 4} having enhanced photocatalytic activity have been synthesized by a facile microwave hydrothermal method. The structural analysis indicates that Gd doping can induce the phase transition from monoclinic to tetragonal BiVO{sub 4}. The reaction results in precursor solutions imply that tetragonal GdVO{sub 4} seeds as crystal nucleus are the original and determined incentives to force the formation of tetragonal Gd-BiVO{sub 4}. The influences of the surface defect, band structure, and BET surface area on the improved photocatalytic activities of tetragonal Gd-doped BiVO{sub 4} are investigated systematically. The results demonstrate that the more surface oxygen deficiencies as active sites and the excellent mobility and separation of photogenerated electrons and holes are beneficial to the enhancement of the photocatalytic performance of tetragonal Gd-BiVO{sub 4}. The RhB photodegradation experiments indicate that the contribution of high photocatalytic activities under simulated sun-light is mainly from UV-light region due to the tetragonal structure feature. The best photocatalytic performance is obtained for tetragonal 10 at% Gd-BiVO{sub 4}, of which the RhB degradation rate can reach to 96% after 120 min simulated sun-light irradiation. The stable tetragonal Gd-BiVO{sub 4} with efficient mineralization will be a promising photocatalytic material applied in water purification.

X-ray Photoelectron Spectroscopy as a tool to investigate silane-based coatings for the protection of outdoor bronze: The role of alloying elements

Science.gov (United States)

Masi, G.; Balbo, A.; Esvan, J.; Monticelli, C.; Avila, J.; Robbiola, L.; Bernardi, E.; Bignozzi, M. C.; Asensio, M. C.; Martini, C.; Chiavari, C.

2018-03-01

Application of a protective coating is the most widely used conservation treatment for outdoor bronzes (cast Cu-Sn-Zn-Pb-Sb alloys). However, improving coating protectiveness requires detailed knowledge of the coating/substrate chemical bonding. This is particularly the case for 3-mercapto-propyl-trimethoxy-silane (PropS-SH) applied on bronze, exhibiting a good protective behaviour in outdoor simulated conditions. The present work deals with X-Ray Photoelectron Spectroscopy (XPS) and Electron Microscopy (FEG-SEM + FIB (Focused Ion Beam)) characterization of a thin PropS-SH film on bronze. In particular, in order to better understand the influence of alloying elements on coating performance, PropS-SH was studied first on pure Cu and Sn substrates then on bronzes with increasing alloy additions: Cu8Sn as well as a quinary Cu-Sn-Zn-Pb-Sb bronze. Moreover, considering the real application of this coating on historical bronze substrates, previously artificially aged ("patinated") bronze samples were prepared and a comparison between bare and "patinated" quinary bronzes was performed. In the case of coated quinary bronze, the free surface of samples was analysed by High Resolution Photoelectron Spectroscopy using Synchrotron Radiation (HR-SRPES) at ANTARES (Synchrotron SOLEIL), which offers a higher energy and lateral resolution. By compiling complementary spectroscopic and imaging information, a deeper insight into the interactions between the protective coating and the bronze substrate was achieved.

Production of multifilamentary Nb3Sn composites incorporating a high tin bronze

International Nuclear Information System (INIS)

Petrovich, A.; Zeithlin, B.A.; Walker, M.S.

1977-01-01

The economics and processing methods have been examined for the fabrication of multifilamentary Nb 3 Sn using a high tin bronze reactive matrix. Four conductor configurations utilizing the high tin bronze were compared with a conventional Cu-13 wt % Sn bronze. The most promising of these designs is potentially 40% lower in cost per ampere meter than the conventional composite. Large hydrostatic extrusion facilities, which are required for the high tin processing, are not presently available in this country but can be made by conversion of conventional presses. They exist in Europe. Experiments were conducted to investigate the applicability of hydrostatic extrusion, and billet components were successfully prepared using the hydrostatic extrusion technique. We have concluded that the economics, availability of facilities and initial fabrication results are favorable for this type of conductor and that the next stage in this program of scale up to extrusion and drawing of 2'' to 3'' diameter composite billets should be undertaken

Determination of concentrations of minor and micro elements in ancient bronze drums artifacts samples by KO-standardization method of neutron activation analysis

International Nuclear Information System (INIS)

Nguyen Tac Anh; Ho Manh Dung; Diep Dinh Hoa; Cao Dong Vu

2000-01-01

The study aims to get a lot information about manufacturers of ancient bronze artifacts and ancient civilization. By KO-standardization method of neutron activation analysis developed in the Nuclear Research Institute, the concentrations of Au, Ag, As, Zn, Sb, Sn elements in ancient bronze alloy samples of 99 bronze artifacts from many excavated archaeological sites at the provinces in Vietnam were determined with uncertainties about ±10%. These elemental concentrations have been utilized in a statistical analysis procedure in order to determine similarities and correlation between the various samples. Th abnormal high of concentrations of noble metals as Au, Ag in ancient bronze indicates that the ancient metallurgists had been interested in role of these metals on sound quality of bronze artifacts. Especially, the concentrations of As in many samples are very high even at about 10%. This gives an evidence that in ancient time the humankind could use bronze As alloy in order to improve quality when they had produced bronze artifacts. (author)

DEGRADATION WORKS OF MONUMENTAL ART CAST BRONZE UNDER THE INFLUENCE OF ENVIRONMENTAL FACTORS

Directory of Open Access Journals (Sweden)

Delia NICA-BADEA

2012-11-01

Full Text Available Intensive pollution, combined with the lack of conservation of monuments exposed to these environments make the main cause of deterioration of cultural objects to atmospheric corrosion metal. This paper proposes a study of the main factors leading to degradation Bronze alloy, cast bronze monuments exposed to open atmosphere: corrosive environmental factors, stability and products of corrosion of bronze. In general, all corrosion products present on a metal surface are indicated as 'skate', can be composed of single-layer or multilayer products. The paper also includes a case study on the influence of environmental factors on degradation Matthias monument statue in Cluj-Napoca, Romania. Visual inspection of the monument informs us that have white spots, gray, reddish not consistent with the base color green patina, surfaces showing depigmentation, the rain washed areas, crystallization, deposition of air-borne particles.

Elemental analysis of ancient Chinese bronze artifacts with external-beam PIXE

International Nuclear Information System (INIS)

Lin, E.K.; Yu, Y.C.; Wang, C.W.; Shen, C.T.; Huang, Y.M.; Wu, S.C.; Hsieh, C.H.

1992-01-01

External-beam PIXE has been applied for the determination of the elemental composition of ancient Chinese bronze artifacts. Characteristic x-ray spectra from the samples bombarded with protons of 3 MeV have been measured with a HPGe detector. At each sample three spots were irradiated per run. Results of measurements on three fragments of bronze drinking vessels and helmet of Chinese ancient Chou and Shang dynasties (17th-8th century B.C.) are presented. To check the analytical method, we have also made measurements on the elemental composition of some modern coins. The results are discussed. (author)

Learners’ Mistakes or Professional Error – the Nordic Bronze Age ornaments

DEFF Research Database (Denmark)

Nørgaard, Heide Wrobel

Nordic Bronze Age ornaments are known for their rich decorations, often consisting of spiral bands used as part of a variety of other decorative elements. Even a cursory examination makes it clear that these ornaments vary greatly in terms of their quality. How can this variation be explained......? Is this the result of different workshops, levels of crafting skills or perhaps even the incorporation of novice metalworkers? As part of a study on craft organization in the Nordic Bronze Age, several metal workshops were analyzed in relation to the skill of the craftsmen and the amount of time involved...

Elemental analysis of ancient Chinese bronze artifacts with external-beam PIXE

Energy Technology Data Exchange (ETDEWEB)

Lin, E.K.; Yu, Y.C.; Wang, C.W.; Shen, C.T.; Huang, Y.M.; Wu, S.C.; Hsieh, C.H. [Academia Sinica, Taipei, TW (China). Inst. of Physics

1992-12-31

External-beam PIXE has been applied for the determination of the elemental composition of ancient Chinese bronze artifacts. Characteristic x-ray spectra from the samples bombarded with protons of 3 MeV have been measured with a HPGe detector. At each sample three spots were irradiated per run. Results of measurements on three fragments of bronze drinking vessels and helmet of Chinese ancient Chou and Shang dynasties (17th-8th century B.C.) are presented. To check the analytical method, we have also made measurements on the elemental composition of some modern coins. The results are discussed. (author).

Provenance study of a Bronze Age sword from Giurgiu

International Nuclear Information System (INIS)

Olariu, Agata; Badica, T.; Popescu, I. V.; Alexandrescu, E.

2000-01-01

This work is a compositional study of a bronze sword recently discovered near Giurgiu using the method of charged particles induced X ray emission (PIXE). The sword is of it Reutlingen type dated in the period Bronze Age D - Hallstatt A1, around 1200 B. C. The knowledge of its composition could give supplementary information about the provenance of this sword by comparing with other copper-based alloy objects from Bronze Age. To obtain the composition of the sword we have applied the method PIXE at the Tandem accelerator of IFIN-HH Magurele. We have extracted 3 samples from the body of the sword: one sample from the tip of the sword and 2 samples from the hilt. The samples have been flattened by a hammer and introduced in the irradiation chamber of the PIXE spectrometer. The targets have been irradiated by a current of protons of 3 MeV and about 5 nA from the linear accelerator Tandem of the department. The detection of the characteristic X ray emission have been done by a GeHP detector. The acquisition of the X ray spectra has been done online on a PC with a MCA interface Canberra. The detection system gave a 190 eV resolution at 5.9 keV. In the frame of the experimental conditions the following elements have been observed: As, Co, Cr, Cu, Fe, Ni, Pb, Sn and Zn. In the table we present the results of the PIXE analysis of the Bronze Age sword from Giurgiu. The instrumentation errors have been less than 15%. The values of the elemental concentrations have been normalized to 100%. In order to have a comparative study of composition we considered also the composition of 7 swords of the same type and from the same period from regions from the south of Danube in Bulgaria, and 6 copper-based alloy objects from Spalnaca deposit, in Transylvania, dated also Bronze Age. The sword from Giurgiu has a composition closer to the Bulgarian swords for the elements: As, Co, Cu, Ni, Sn. The ratios Sn/Cu versus As/Cu for the sword from Giurgiu, Spalnaca-Transylvania objects and

Quantitative multiphase analysis of archaeological bronzes by neutron diffraction

CERN Document Server

Siano, S; Celli, M; Pini, R; Salimbeni, R; Zoppi, M; Kockelmann, W A; Iozzo, M; Miccio, M; Moze, O

2002-01-01

In this paper, we report the first investigation on the potentials of neutron diffraction to characterize archaeological bronze artifacts. The preliminary feasibility of phase and structural analysis was demonstrated on standardised specimens with a typical bronze alloy composition. These were realised through different hardening and annealing cycles, simulating possible ancient working techniques. The Bragg peak widths that resulted were strictly dependent on the working treatment, thus providing an important analytical element to investigate ancient making techniques. The diagnostic criteria developed on the standardised specimens were then applied to study two Etruscan museum pieces. Quantitative multiphase analysis by Rietveld refinement of the diffraction patterns was successfully demonstrated. Furthermore, the analysis of patterns associated with different artifact elements also yielded evidence for some peculiar perspective of the neutron diffraction diagnostics in archeometric applications. (orig.)

Pressure induced phase transitions in ceramic compounds containing tetragonal zirconia

Energy Technology Data Exchange (ETDEWEB)

Sparks, R.G.; Pfeiffer, G.; Paesler, M.A.

1988-12-01

Stabilized tetragonal zirconia compounds exhibit a transformation toughening process in which stress applied to the material induces a crystallographic phase transition. The phase transition is accompanied by a volume expansion in the stressed region thereby dissipating stress and increasing the fracture strength of the material. The hydrostatic component of the stress required to induce the phase transition can be investigated by the use of a high pressure technique in combination with Micro-Raman spectroscopy. The intensity of Raman lines characteristic for the crystallographic phases can be used to calculate the amount of material that has undergone the transition as a function of pressure. It was found that pressures on the order of 2-5 kBar were sufficient to produce an almost complete transition from the original tetragonal to the less dense monoclinic phase; while a further increase in pressure caused a gradual reversal of the transition back to the original tetragonal structure.

Early Bronze Age Houses in Upper Mesopotamia: Evidence of Dwellings or Private Enterprises?

OpenAIRE

Mas, Juliette

2014-01-01

This paper deals with the research I carried out on domestic architecture and private economy during Early Bronze Age in Upper-Mesopotamia. Archaeological records, as well as textual evidence, has been used to try to define private households activities and their relationships with official institutions. Households were the main source of production, distribution and consumption during the Early Bronze Age. As it seems that these private economic entities produced goods and crafts in their ow...

Positron annihilation in sodium and copper β-vanadium oxide bronzes

International Nuclear Information System (INIS)

Dryzek, J.; Rogowska, E.

1990-01-01

Studies of copper and sodium β-vanadium oxide bronzes are performed using positron annihilation measured with a long slit angular correlation apparatus. The dependences of peak coincidence rate on temperature (40 to 310deg C) are obtained for different concentrations of donor atoms in the case of copper vanadium oxide bronzes. A three-states model corresponding to the annihilation of positrons in donor atom sublattice is applied for the description of the experimental data. The creation enthalpy of vacancies for that sublattice is equal to (0.60 ± 0.01) eV for Na 0.33 V 2 O 5 and equal to (0.64 ± 0.01) eV for Cu x V 2 O 5 . (author)

Fe-Vacancy-Induced Ferromagnetism in Tetragonal FeSe Thin Films

International Nuclear Information System (INIS)

Yong-Feng, Li; Gui-Bin, Liu; Li-Jie, Shi; Bang-Gui, Liu

2009-01-01

Motivated by recent experiments, we investigate structural, electronic, and magnetic properties of tetragonal FeSe with Fe vacancies using the state-of-the-art first-principles method. We show that Fe vacancies tend to stay in the same one of the two sublattices and thus induce ferromagnetism in the ground-state phase. Our calculated net moment is in good agreement with the experimental data available. Therefore, the ferromagnetism observed in tetragonal FeSe thin films is explained. It could be made controllable soon for spintronic applications

Phase field modelling of precipitate morphologies in systems with tetragonal interfacial free energy anisotropy

OpenAIRE

Roy, Arijit; Gururajan, M P

2017-01-01

A wide variety of morphologies arise due to the tetragonal anisotropy in interfacial free energy. In this paper, we report on a family of Extended Cahn-Hilliard (ECH) models for incorporating tetragonal anisotropy in interfacial free energy. We list the non-zero and independent parameters that are introduced in our model and list the constraints on them. For appropriate choice of these parameters, our model can produce a many of the morphologies seen in tetragonal systems such as di-pyramids,...

Highly Stable Aqueous Zinc-ion Storage Using Layered Calcium Vanadium Oxide Bronze Cathode

KAUST Repository

Xia, Chuan; Guo, Jing; Li, Peng; Zhang, Xixiang; Alshareef, Husam N.

2018-01-01

Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn2+ intercalation chemistry, stand out as they can employ high-capacity Zn metal as anode material. Herein, we report a layered calcium vanadium oxide bronze as cathode material for aqueous Zn batteries. For the storage of Zn2+ ions in aqueous electrolyte, we demonstrate that calcium based bronze structure can deliver a high capacity of 340 mAh g-1 at 0.2 C, good rate capability and very long cycling life (96% retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 Wh kg-1 at a power density of 53.4 W kg-1.

Highly Stable Aqueous Zinc-ion Storage Using Layered Calcium Vanadium Oxide Bronze Cathode

KAUST Repository

Xia, Chuan

2018-02-12

Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn2+ intercalation chemistry, stand out as they can employ high-capacity Zn metal as anode material. Herein, we report a layered calcium vanadium oxide bronze as cathode material for aqueous Zn batteries. For the storage of Zn2+ ions in aqueous electrolyte, we demonstrate that calcium based bronze structure can deliver a high capacity of 340 mAh g-1 at 0.2 C, good rate capability and very long cycling life (96% retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 Wh kg-1 at a power density of 53.4 W kg-1.

Corrosion investigation of fire-gilded bronze involving high surface resolution spectroscopic imaging

International Nuclear Information System (INIS)

Masi, G.; Chiavari, C.; Avila, J.; Esvan, J.; Raffo, S.; Bignozzi, M.C.; Asensio, M.C.; Robbiola, L.

2016-01-01

Graphical abstract: - Highlights: • Fire-gilded bronze prepared by ancient methods (Au–Hg layer on Cu–Sn–Zn–Pb–Sb). • Heating during gilding induces Sn and Znenrichment in the top part of the gilded layer. • SR-HRPES mapping of corrosion craters (cross-section) after accelerated ageing. • Selective dissolution of Cu and Zn in the craters induces Sn species enrichment. • The main species in the craters are related to hydroxi-oxide compounds. - Abstract: Gilded bronzes are often affected by severe corrosion, due to defects in the Au layer and Au/Cu alloy galvanic coupling, stimulated by large cathodic area of the gilded layer. Galvanic corrosion, triggered by gilding defects, leads to products growth at the Au/bronze interface, inducing blistering or break-up of the Au layer. In this context, fire-gilded bronze replicas prepared by ancient methods (use of spreadable Au–Hg paste) was specifically characterised by compiling complementary spectroscopic and imaging information before/after accelerated ageing with synthetic rain. Fire-gilded bronze samples were chemically imaged in cross-section at nano-metric scale (<200 nm) using high energy and lateral resolution synchrotron radiation photoemission (HR-SRPES) of core levels and valence band after conventional characterisation of the samples by Glow Discharge optical Emission Spectroscopy (GD-OES) and conventional X-ray photoelectron spectroscopy (XPS). We have found a net surface enrichment in Zn and Sn after fire-gilding and presence of metallic Hg, Pb and Cu within the Au layer. Moreover, the composition distribution of the elements together with their oxidation has been determined. It was also revealed that metallic phases including Hg and Pb remain in the gilding after corrosion. Moreover, selective dissolution of Zn and Cu occurs in the crater due to galvanic coupling, which locally induces relative Sn species enrichment (decuprification). The feasibility advantages and disadvantages of

Corrosion investigation of fire-gilded bronze involving high surface resolution spectroscopic imaging

Energy Technology Data Exchange (ETDEWEB)

Masi, G., E-mail: giulia.masi5@unibo.it [Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, Università di Bologna, via Terracini 28, 40131 Bologna (Italy); Chiavari, C., E-mail: cristina.chiavari@unibo.it [Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, Università di Bologna, via Terracini 28, 40131 Bologna (Italy); C.I.R.I. (Centro Interdipartimentale Ricerca Industriale) Meccanica Avanzata e Materiali, Università di Bologna, Bologna, via Terracini 28, 40131 Bologna (Italy); Avila, J., E-mail: jose.avila@synchrotron-soleil.fr [Synchrotron SOLEIL, L’Orme des Merisiers, 91190 Saint-Aubin (France); Esvan, J., E-mail: jerome.esvan@ensiacet.fr [Centre Interuniversitaire de Recherche et d’Ingénierie des Matériaux, Université de Toulouse, 4 allée Emile Monso, 31030 Toulouse (France); Raffo, S., E-mail: simona.raffo2@unibo.it [Dipartimento di Chimica Industriale “Toso Montanari”, Università di Bologna, viale Risorgimento 4, 40136 Bologna (Italy); Bignozzi, M.C., E-mail: maria.bignozzi@unibo.it [Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, Università di Bologna, via Terracini 28, 40131 Bologna (Italy); Asensio, M.C., E-mail: maria-carmen.asensio@synchrotron-soleil.fr [Synchrotron SOLEIL, L’Orme des Merisiers, 91190 Saint-Aubin (France); Robbiola, L., E-mail: robbiola@univ-tlse2.fr [TRACES Lab (CNRS UMR5608), Université Toulouse Jean-Jaurès, 5, allées Antonio-Machado, 31058 Toulouse (France); and others

2016-03-15

Graphical abstract: - Highlights: • Fire-gilded bronze prepared by ancient methods (Au–Hg layer on Cu–Sn–Zn–Pb–Sb). • Heating during gilding induces Sn and Znenrichment in the top part of the gilded layer. • SR-HRPES mapping of corrosion craters (cross-section) after accelerated ageing. • Selective dissolution of Cu and Zn in the craters induces Sn species enrichment. • The main species in the craters are related to hydroxi-oxide compounds. - Abstract: Gilded bronzes are often affected by severe corrosion, due to defects in the Au layer and Au/Cu alloy galvanic coupling, stimulated by large cathodic area of the gilded layer. Galvanic corrosion, triggered by gilding defects, leads to products growth at the Au/bronze interface, inducing blistering or break-up of the Au layer. In this context, fire-gilded bronze replicas prepared by ancient methods (use of spreadable Au–Hg paste) was specifically characterised by compiling complementary spectroscopic and imaging information before/after accelerated ageing with synthetic rain. Fire-gilded bronze samples were chemically imaged in cross-section at nano-metric scale (<200 nm) using high energy and lateral resolution synchrotron radiation photoemission (HR-SRPES) of core levels and valence band after conventional characterisation of the samples by Glow Discharge optical Emission Spectroscopy (GD-OES) and conventional X-ray photoelectron spectroscopy (XPS). We have found a net surface enrichment in Zn and Sn after fire-gilding and presence of metallic Hg, Pb and Cu within the Au layer. Moreover, the composition distribution of the elements together with their oxidation has been determined. It was also revealed that metallic phases including Hg and Pb remain in the gilding after corrosion. Moreover, selective dissolution of Zn and Cu occurs in the crater due to galvanic coupling, which locally induces relative Sn species enrichment (decuprification). The feasibility advantages and disadvantages of

Crystal Structure of Tetragonal Form of La2NiO4+x

Science.gov (United States)

Kajitani, Tsuyoshi; Hosoya, Syoichi; Hirabayashi, Makoto; Fukuda, Tsuguo; Onozuka, Takashi

1989-10-01

The crystal structure of the title oxide was studied by means of the X-ray and neutron single crystal diffraction measurements. At room temperature, the tetragonal crystal structure is P42/ncm-type (No. 138), which is one of the subgroup of the space group I4/mmm. The lattice parameters of a sample annealed and slowly cooled in oxygen atmosphere from 673 K are a{=}b{=}5.4640(1) Å and c{=}12.6719(2) Å, while the oxygen content, x{=}0.10(4), was determined from obtained neutron data. The title oxide undergoes a tetragonal (P42/ncm)/tetragonal (I4/mmm) phase transition at about 560 K. The transition temperature is almost identical both in the annealed and as-grown crystals.

Palaeoethnobotanical Data from the High Mountainous Early Bronze Age Settlement of Tsaghkasar-1 (Mt. Aragats, Armenia

Directory of Open Access Journals (Sweden)

Roman Hovsepyan

2011-09-01

Full Text Available Palaeoethnobotanical investigations suggest that at least part of the Early Bronze Age population of Tsaghkasar was settled and practiced agriculture in the high mountainous zone. People there appear to have cultivated hexa‐ and tetraploid wheats (probably bread wheat and emmer and barley (possibly hulled. Bronze Age agriculture in the Southern Caucasus differs from earlier and later period when cultivation of pulses, oil‐producing plants, and other plants was common. This emphasis on the cultivation and use of certain cereal grains at Early Bronze sites such as Tsaghkasar can tentatively be added to a constellation of practices associated with the Kura‐Araxes culture in the South Caucasus.

Pressure Effects on Solid State Phase Transformation of Aluminium Bronze in Cooling Process

International Nuclear Information System (INIS)

Hai-Yan, Wang; Jian-Hua, Liu; Gui-Rong, Peng; Yan, Chen; Yu-Wen, Liu; Fei, Li; Wen-Kui, Wang

2009-01-01

Effects of high pressure (6 GPa) on the solid state phase transformation kinetic parameters of aluminum bronze during the cooling process are investigated, based on the measurement and calculation of its solid state phase transformation temperature, duration and activation energy and the observation of its microstructures. The results show that high pressure treatment can reduce the solid phase transformation temperature and activation energy in the cooling process and can shorten the phase transformation duration, which is favorable when forming fine-grained aluminum bronze

Thermodynamic analysis of the formation of tetragonal bainite in steels

Science.gov (United States)

Mirzayev, D. A.; Mirzoev, A. A.; Buldashev, I. V.; Okishev, K. Yu.

2017-06-01

In the articles of Bkhadeshia, a new class of high-strength steels based on the structure of carbidefree bainite with an enhanced carbon content has been developed. According to Bkhadeshia, the main factor responsible for the high solubility of carbon is the occurrence of a tetragonality of the bainite lattice. To check this effect, in this article, the theory of tetragonality of martensite of iron alloys developed by Zener and Khachaturyan was applied to bainite under the assumption that the precipitation of carbides is prohibited. Equations for the chemical potentials of carbon and iron in austenite and in tetragonal ferrite have been derived. The equilibrium of these phases has been considered, and the calculations of the boundary concentrations of carbon and iron at different temperatures (300-1000 K) and at different parameters of the deformation interaction λ0 have been performed. The rigorous calculations confirmed Bkhadeshia's hypothesis that the suppression of the carbide formation during the formation of bainite leads to an increase in the carbon solubility in the bcc phase.

Nucleation in stress-induced tetragonal-monoclinic transformation of constrained zirconia

International Nuclear Information System (INIS)

Chan, S.K.

1992-08-01

A theory for stress-induced tetragonal→monoclinic transformation of constrained zirconia is presented based on the assumption that when forcibly strained to a regime of absolute instability where the free energy density of the tetragonal phase has a negative curvature, the constrained tetragonal zirconia becomes unstable with respect to the development of a modulated strain pattern that will evolve into a band of twin monoclinic domains. The temperature range for such an instability, the critical size of the inclusion, the corresponding critical strain, and the periodicity of the modulation are derived in terms of parameters that can be related to the elastic stiffness coefficients of various orders of the inclusion and the shear modulus of the host matrix. An entirely different mechanism is suggested for the reverse monoclinic→tetragonal transformation because the monoclinic phase is metastable when the extrinsic stress is removed. Estimates for the parameters are inferred from a variety of experimental data for pure zirconia and the numerical values for the predicted physical quantities are obtained

Bioarchaeology of adaptation to a marginal environment in bronze age Western China.

Science.gov (United States)

Berger, Elizabeth; Wang, Hui

2017-07-08

This study examines human adaptation to the 4000 BP climate change event, which is said to have increased the marginality of Inner Asian environments. We propose to define "marginal" environments not in relation to a specific economic activity (e.g., agriculture), but in relation to whether humans living there are physiologically stressed. Three sites in the Hexi Corridor of Gansu were studied, one from the early and two from the late Bronze Age (N = 125). The study includes three indicators of physiological stress: linear enamel hypoplasias (LEH); tibial periosteal lesions; and fertility. The early and late Bronze Age groups were compared to examine whether human physiological stress increased. The percent of individuals with LEH declined dramatically, indicating fewer growth disruptions. Tibial periosteal reactions also changed, from mostly active to mostly healing at the time of death, indicating that frailty declined. Fertility, which is sensitive to changes in population health and resource availability, did not change significantly. Counter to the dominant narrative of environmental deterioration and subsistence system collapse, the Bronze Age residents of the Hexi Corridor show no skeletal evidence that they suffered from resource shortages or struggled to adapt in the fluctuating climate that pertained after the 4000 BP climate event. In fact, this study found that people suffered from less frailty and fewer growth disruptions after the unstable climate had persisted for some time. Therefore, in human biological terms, the Hexi Corridor did not become more marginal for human habitation during the Bronze Age. © 2017 Wiley Periodicals, Inc.

Synchrotron radiation-based x-ray analysis of bronze artifacts from an Iron Age site in the Judean hills

International Nuclear Information System (INIS)

Friedman, E. S.; Brody, A. J.; Young, M. L.; Almer, J. D.; Serge, C. U.; Mini, S. M.

2008-01-01

Seven bronze bangles from Tell en-Nasbeh, northern Judah, were investigated to understand the phase composition and manufacturing process of the artifacts, and possibly suggest a provenance for their origin. Synchrotron x-ray radiation diffraction (XRD) and fluorescence (XRF) were used in the analysis to avoid any destructive sampling and at the same time penetrate through the surface into the core metal. These techniques enabled us to determine that the bangles were not just tin bronze, but leaded tin bronze. Based on excavation reports, it is unlikely that the metal objects were manufactured locally at Tell en-Nasbeh; rather, preliminary XRD and XRF data point towards the neighboring region of Edom as their origin. Despite their political enmity during the Iron Age II, the data suggest that Judahite social demands for bronze may have fostered a strong economic relationship between these two polities

Elemental analysis of bronze artifacts by muonic X-ray spectroscopy

International Nuclear Information System (INIS)

Ninomiya, Kazuhiko; Shinohara, Atsushi; Kubo, Michael K.; Strasser, Patrick; Nagatomo, Takashi; Kawamura, Naritoshi; Shimomura, Koichiro; Miyake, Yasuhiro; Kobayashi, Yoshio; Ishida, Katsuhiko; Higemoto, Wataru; Suzuki, Takao; Saito, Tsutomu

2015-01-01

A quantitative and multi-elemental analysis method for bulk samples based on muonic X-ray spectroscopy was applied to bronze artifacts (Tempo-Tsuho coins and a Seiun-kyo mirror). This method is based on the measurement of the characteristic high-energy muonic X-rays emitted in a sample after muon irradiation. The elemental compositions of these bronze artifacts were determined from muonic X-ray intensities in a non-destructive manner, using the relation between the muonic X-ray intensity and the elemental composition of the Cu–Sn–Pb alloy system. The analyzed values agreed well with those determined by X-ray fluorescence spectroscopy. We also estimated the detection limit of this method in the present experimental setup as 0.81 wt% of the background signal of the muonic X-ray spectra. (author)

Breakthrough of the Nordic Bronze Age: Transcultural warriorhood and a Carpathian crossroad in the 16th century BC

DEFF Research Database (Denmark)

Vandkilde, Helle

2014-01-01

The breakthrough of the Nordic Bronze Age (NBA) c. 1600 bc as a koiné within Bronze Age Europe can be historically linked to the Carpathian Basin. Nordic distinctiveness entailed an entanglement of cosmology and warriorhood, albeit represented through different media in the hotspot zone (bronze) ...... momentous creativity that drew upon Carpathian originals, contacts and a pool of Carpathian ideas, but ultimately drawing on emergent Mycenaean hegemonies in the Aegean. This provided the incentive for a cosmology-rooted resource from which the NBA could take its starting point....

Application of microjet in heat treatment of aluminium bronzes

Directory of Open Access Journals (Sweden)

Z. Górny

2011-04-01

Full Text Available Mechanical properties of a CuAl10Fe4Ni4 bronze subjected to solution heat treatment and toughening were examined. In solution heattreatment, a microjet was used to raise the cooling rate. A slight increase of mechanical properties was observed.

青铜乐器自名研究%A Study of the Names Inscribed on Bronze Musical Instruments

Institute of Scientific and Technical Information of China (English)

陈双新

2001-01-01

Based on his studies of the bronze musical instruments, the author analyses the inscriptions referring the self-named modifiers and tries to give them new explanations. The study is important to understand the function and values of the bronze musical instruments.

Formation of metastable tetragonal zirconia nanoparticles: Competitive influence of the dopants and surface state

Energy Technology Data Exchange (ETDEWEB)

Gorban, Oksana, E-mail: matscidep@aim.com [Donetsk Institute for Physics and Engineering named after A.A. Galkin of the NAS of Ukraine, Nauki av. 46, Kyiv 03680 (Ukraine); Synyakina, Susanna; Volkova, Galina; Gorban, Sergey; Konstantiova, Tetyana [Donetsk Institute for Physics and Engineering named after A.A. Galkin of the NAS of Ukraine, Nauki av. 46, Kyiv 03680 (Ukraine); Lyubchik, Svetlana, E-mail: s_lyubchik@yahoo.com [REQUIMTE, Universida de Nova de Lisboa, 2829-516 Caparica (Portugal)

2015-12-15

The effect of the surface modification of the nanoparticles of amorphous and crystalline partially stabilized zirconia by fluoride ions on stability of the metastable tetragonal phase was investigated. Based on the DSC, titrimetry and FTIR spectroscopy data it was proven that surface modification of the xerogel resulted from an exchange of the fluoride ions with the basic OH groups. The effect of the powder pre-calcination temperature before modification on the formation of metastable tetragonal phase in partially stabilized zirconia was investigated. It was shown that the main factor of tetragonal zirconia stabilization is the state of nanoparticles surface at pre-crystallization temperatures.

Non-invasive chemical and phase analysis of Roman bronze artefacts from Thamusida (Morocco)

Energy Technology Data Exchange (ETDEWEB)

Gliozzo, Elisabetta, E-mail: gliozzo@unisi.i [Dipartimento di Scienze della Terra, Universita di Siena, via Laterina 8, 53100 Siena (Italy); Arletti, Rossella, E-mail: rarletti@unimore.i [Dipartimento di Scienze della Terra, Universita di Modena e Reggio Emilia, Largo S. Eufemia 19, 41100 Modena (Italy); Cartechini, Laura, E-mail: laura@thch.unipg.i [Istituto di Scienze e Tecnologie Molecolari del CNR (CNR-ISTM), c/o Dipartimento di Chimica, Universita di Perugia, via Elce di Sotto 8, 06123 Perugia (Italy); Dipartimento di Chimica, Universita di Perugia, via Elce di Sotto 8, 06123 Perugia (Italy); Imberti, Silvia, E-mail: Silvia.Imberti@stfc.ac.u [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, OX11 0QX (United Kingdom); Kockelmann, Winfried A., E-mail: Winfried.Kockelmann@stfc.ac.u [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, OX11 0QX (United Kingdom); Memmi, Isabella, E-mail: memmi@unisi.i [Dipartimento di Scienze della Terra, Universita di Siena, via Laterina 8, 53100 Siena (Italy); Rinaldi, Romano, E-mail: rrinaldi@unipg.i [Dipartimento di Chimica, Universita di Perugia, via Elce di Sotto 8, 06123 Perugia (Italy); Tykot, Robert H., E-mail: rtykot@cas.usf.ed [Department of Anthropology, University of South Florida, Tampa, FL 33620 (United States)

2010-12-15

A repertory of Roman military bronze equipment (1st- 3rd century AD) found at the archaeological site of Thamusida (Rabat, Morocco) was analysed by non-destructive X-ray fluorescence and time of flight neutron diffraction (TOF-ND). Most objects are made of leaded alloys, where copper is combined with tin and/or zinc and, in six cases, to arsenic as well. A mixed technology was employed, making a limited use of 'pure' semi-finished materials if compared with the large utilization of recycled materials (brass and bronze).

Surface characterization of a corroded bronze-leaded alloy in a salt spray cabinet

International Nuclear Information System (INIS)

Cura D'Ars de Figueiredo Junior, Joao; Freitas Cunha Lins, Vanessa de; Bellis, Vito Modesto de

2007-01-01

The corrosion products of a TM 23 bronze-leaded alloy (Cu 72%, Pb 15%, Zn 8% and Sn 5%) were obtained in a salt spray cabinet after exposition during 120 h and 1000 h. The products obtained were studied using scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The major products of bronze-leaded corrosion were oxides and basic salts of Cu, CuCl 2 .3Cu(OH) 2 , and Pb, Pb(OH)Cl. The results can be attributed to a kinetic control of the corrosion reactions

14C dating of the Early to Late Bronze Age stratigraphic sequence of Aegina Kolonna, Greece

International Nuclear Information System (INIS)

Wild, E.M.; Gauss, W.; Forstenpointner, G.; Lindblom, M.; Smetana, R.; Steier, P.; Thanheiser, U.; Weninger, F.

2010-01-01

Aegina Kolonna, located in the center of the Saronic Gulf in the Aegean Mediterranean (Greece), is one of the major archaeological sites of the Aegean Bronze Age with a continuous stratigraphic settlement sequence from the Late Neolithic to the Late Bronze Age. Due to its position next to the maritime cross roads between central mainland Greece, the northeast Peloponnese, the Cyclades and Crete, the island played an important role in the trade between these regions. In the course of new excavations, which focused on the exploration of the Early, Middle and Late Bronze Age at Kolonna, several short lived samples from different settlement phases have been 14 C-dated with the AMS method at the VERA laboratory. Bayesian sequencing of the 14 C data according to the stratigraphic position of the samples in the profile was performed to enable estimates of the transition time between the cultural phases. The Aegina Kolonna 14 C sequence is one of the longest existing so far for the Aegean Bronze Age, and therefore of major importance for the absolute Bronze Age chronology in this region. Preliminary results indicate that the Middle Helladic period seems to have started earlier and lasted longer than traditionally assumed. Further, at the present stage of our investigation we can give also a very tentative time frame for the Santorini volcanic eruption which seems to be in agreement with the science derived VDL date.

Building the Bronze Age : Architectural and social change on the Greek mainland during Early Helladic III, Middle Helladic and Late Helladic I

NARCIS (Netherlands)

Wiersma, Corien

2014-01-01

Communities living on the Greek Mainland during the end of the Early Bronze Age (EBA. ca. 2200-2000 BC) and the earlier Middle Bronze Age (MBA, ca. 2000-1800 BC) were thought to be relatively simple and egalitarian, while during the later MBA and early Late Bronze Age (LBA, ca. 1700-1600 BC),

Examination of Ife Bronze Casting Culture and Its Decline in ...

African Journals Online (AJOL)

DrNneka

civilization and culture, education, science and technology. ... to set up bronze casting industry to promote the commercial culture in the history of. Ife. ..... the development of science and technological advancement, while to others; it is the.

Aromatic quinoxaline as corrosion inhibitor for bronze in aqueous ...

Indian Academy of Sciences (India)

Administrator

These compounds act through the formation of a protective film on the surface of the ... Bronze; inhibitors; quinoxalin compounds; chloride solution; electrochemical studies. 1. ... elements such as aluminum, nickel and iron offer a good ... cations such as pump casting, valves and heat exchanger. ..... to investigate this layer.

Casting Simulation of an Austrian Bronze Age Sword Hilt

Science.gov (United States)

Pola, Annalisa; Mödlinger, Marianne; Piccardo, Paolo; Montesano, Lorenzo

2015-07-01

Bronze Age swords with a metal hilt can be considered the peak of Bronze Age casting technologies. To reconstruct the casting techniques used more than 3000 years ago, a metal hilted sword of the Schalenknauf type from Lower Austria was studied with the aid of macroscopic analyses and simulation of mold filling and casting solidification. A three-dimensional model of the hilt was created based on optical scanner measurements performed on a hilt recently discovered during archaeological excavations. Three different configurations of the gating system were considered, two on the pommel disk and one on the knob, and the effect of its location on the formation of casting defects was investigated. Three-dimensional computed tomography was used to detect internal defects, such as gas and shrinkage porosity, which were then compared with those calculated by simulation. The best match between actual and predicted hilt quality demonstrated the location of the gating system, which turned out to be on the pommel disk.

Standard formation enthalpies of Nasub(2+x)Vsub(6)Osub(16-y) bronze of kappa type

International Nuclear Information System (INIS)

Khodos, M.Ya.; Slobodin, B.V.; Surat, L.L.; Fotiev, A.A.

1980-01-01

Standard formation enthalpies of sodium oxide vanadium bronze of kappa Nasub(2+x)Vsub(6)Osub(16-y) type of different composition have been determined by the method of solution calorimetry. It has been ascertained that within the limits of homogeneity a standard formation enthalpy decreases insignificantly with the increase of bronze oxygen defectiveness and is a linear function of sodium content

Chisels in the italian Bronze Age: technological and typological aspects

Directory of Open Access Journals (Sweden)

Speciale, Claudia

2010-12-01

Full Text Available Bronze chisels are tools used “à percussion posée”; this means they need a minimum length and some functional parts (tang, body, blade; they could have a handle of perishable material and they were used with a hammer to work wood, bronze and other materials. Chisels can be classified following their functional parts; the first element is the shape (rod or socketed chisel; the second one is body section; the third one is tang section. Chronology and distribution of every type were identified to obtain a general view of this class of tools during the Italian Bronze Age.

Los cinceles de bronce son herramientas que se utilizan en percusión apoyada (à percussion posée, por consiguiente, necesitan una longitud mínima y algunas partes funcionales (empuñadura, cuerpo, hoja; podrían tener un mango de material perecedero. Se utilizan con un martillo en el labrado de la madera, del bronce y de otros materiales. Los cinceles se pueden clasificar de acuerdo con los siguientes elementos funcionales: el primero es la forma (cincel de varilla o de cubo; el segundo es la sección del cuerpo; el tercero es la sección de la empuñadura. La cronología y la distribución de cada tipo se identificaron para obtener una visión general de esta clase de instrumentos durante la Edad del Bronce en Italia.

Tamil Chola Bronzes and Swamimalai Legacy: Metal Sources and Archaeotechnology

Science.gov (United States)

Srinivasan, Sharada

2016-08-01

This review explores the great copper alloy image casting traditions of southern India from archaeometallurgical and ethnometallurgical perspectives. The usefulness of lead isotope ratio and compositional analysis in the finger-printing and art historical study of more than 130 early historic, Pallava, Chola, later Chola, and Vijayanagara sculptures (fifth-eighteenth centuries) is highlighted, including Nataraja, Buddha, Parvati, and Rama images made of copper, leaded bronze, brass, and gilt copper. Image casting traditions at Swamimalai in Tamil Nadu are compared with artistic treatises and with the technical examination of medieval bronzes, throwing light on continuities and changes in foundry practices. Western Indian sources could be pinpointed for a couple of medieval images from lead isotope analysis. Slag and archaeometallurgical investigations suggest the exploitation of some copper and lead-silver sources in the Andhra and Karnataka regions in the early historic Satavahana period and point to probable copper sources for the medieval images in Karnataka, Tamil Nadu, and Andhra Pradesh. The general lower iron content in southern Indian bronzes perhaps renders the proximal copper-magnetite reserves of Seruvila in Sri Lanka as a less likely source. Given the lack of lead deposits in Sri Lanka, however, the match of the lead isotope signatures of a well-known Ceylonese Buddhist Tara in British Museum with a Buddha image from Nagapattinam in Tamil Nadu may underscore ties between the island nation and the southern Indian Tamil regions.

48 CFR 252.216-7000 - Economic price adjustment-basic steel, aluminum, brass, bronze, or copper mill products.

Science.gov (United States)

2010-10-01

...-basic steel, aluminum, brass, bronze, or copper mill products. 252.216-7000 Section 252.216-7000 Federal... adjustment—basic steel, aluminum, brass, bronze, or copper mill products. As prescribed in 216.203-4-70(a... Mill Products (JUL 1997) (a) Definitions. As used in this clause— Established price means a price which...

Effect of bronze on the compression of Nb3Sn in multifilamentary conductors

International Nuclear Information System (INIS)

Rupp, G.

1978-01-01

Nb 3 Sn in multifilamentary conductors is subject to compressive strain as a result of the relatively small thermal contraction of the filaments as compared to bronze. The critical current Isub(c) is consequently degraded. The critical current increases, when an external tensile stress is applied, and passes through a maximum. The ratio of the maximum critical current to the initial critical current increases with the flux density and reaches a value of two at a flux density of 16 T for technical conductors. The strain epsilonsub(m), at which Isub(c) maximum is reached, lies between 0.4% and 0.7% for the conductors investigated and depends on the material parameters. For a constant ratio of bronze to filament cross section this strain epsilonsub(m) is reduced as the Nb 3 Sn layer thickness is increased and can be determined approximately by a graphical method from the stress-strain diagram. Epsilonsub(m) is to a large extent dependent on the metallurgical properties of bronze, which vary to a considerable extent depending upon the heat treatment. (author)

Foraging behaviour in tadpoles of the bronze frog Rana temporalis ...

Indian Academy of Sciences (India)

Unknown

The ability of bronze frog Rana temporalis tadpoles (pure or mixed parental lines) to ... less of whether they are siblings or non-siblings in a group, which correlates well with ..... Sutherland W J and Parker G A 1992 The relationship between.

Use of portable X-ray fluorescence instrument for bulk alloy analysis on low corroded indoor bronzes

International Nuclear Information System (INIS)

Šatović, D.; Desnica, V.; Fazinić, S.

2013-01-01

One of the most often used non-destructive methods for elemental analysis when performing field measurements on bronze sculptures is X-ray fluorescence (XRF) analysis based on portable instrumentation. However, when performing routine in-situ XRF analysis on corroded objects obtained results are sometimes considerably influenced by the corrosion surface products. In this work the suitability of portable XRF for bulk analysis of low corroded bronzes, which were initially precisely characterized using sophisticated and reliable laboratory methods, was investigated and some improvements in measuring technique and data processing were given. Artificially corroded bronze samples were analyzed by a portable XRF instrument using the same methodology and procedures as when performing in-situ analysis on real objects. The samples were first investigated using sophisticated complementary laboratory techniques: Scanning Electron Microscopy, Proton-Induced X-ray Emission Spectroscopy and Rutherford Backscattering Spectrometry, in order to gain precise information on the formation of the corrosion product layers and in-depth elemental profile of corrosion layers for different aging parameters. It has been shown that for corrosion layers of up to ca. 25 μm a portable XRF can yield very accurate quantification results. - Highlights: • XRF quantification is very accurate for bronze corrosion layers of up to ca. 25 μm. • Corrosion layer formation on bronze described in two phases. • Corrosion layers precisely characterized using PIXE, RBS and SEM. • Corrosion approximated as CuO for layer thickness calculations via X-ray attenuations • Increasingly lighter corrosion matrix may cause SnLα radiation intensity inversion

Use of portable X-ray fluorescence instrument for bulk alloy analysis on low corroded indoor bronzes

Energy Technology Data Exchange (ETDEWEB)

Šatović, D., E-mail: dsatovic@alu.hr [Department of Conservation and Restoration, Academy of Fine Arts, Ilica 85, 10000 Zagreb (Croatia); Desnica, V. [Department of Conservation and Restoration, Academy of Fine Arts, Ilica 85, 10000 Zagreb (Croatia); Fazinić, S. [Laboratory for Ion Beam Interactions, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb (Croatia)

2013-11-01

One of the most often used non-destructive methods for elemental analysis when performing field measurements on bronze sculptures is X-ray fluorescence (XRF) analysis based on portable instrumentation. However, when performing routine in-situ XRF analysis on corroded objects obtained results are sometimes considerably influenced by the corrosion surface products. In this work the suitability of portable XRF for bulk analysis of low corroded bronzes, which were initially precisely characterized using sophisticated and reliable laboratory methods, was investigated and some improvements in measuring technique and data processing were given. Artificially corroded bronze samples were analyzed by a portable XRF instrument using the same methodology and procedures as when performing in-situ analysis on real objects. The samples were first investigated using sophisticated complementary laboratory techniques: Scanning Electron Microscopy, Proton-Induced X-ray Emission Spectroscopy and Rutherford Backscattering Spectrometry, in order to gain precise information on the formation of the corrosion product layers and in-depth elemental profile of corrosion layers for different aging parameters. It has been shown that for corrosion layers of up to ca. 25 μm a portable XRF can yield very accurate quantification results. - Highlights: • XRF quantification is very accurate for bronze corrosion layers of up to ca. 25 μm. • Corrosion layer formation on bronze described in two phases. • Corrosion layers precisely characterized using PIXE, RBS and SEM. • Corrosion approximated as CuO for layer thickness calculations via X-ray attenuations • Increasingly lighter corrosion matrix may cause SnLα radiation intensity inversion.

Community Geothermal Technology Program: Silica bronze project. Final report

Energy Technology Data Exchange (ETDEWEB)

Bianchini, H.

1989-10-01

Objective was to incorporate waste silica from the HGP-A geothermal well in Pohoiki with other refractory materials for investment casting of bronze sculpture. The best composition for casting is about 50% silica, 25% red cinders, and 25% brick dust; remaining ingredient is a binder, such as plaster and water.

Friction Stir Processing Parameters and Property Distributions in Cast Nickel Aluminum Bronze

National Research Council Canada - National Science Library

Rosemark, Brian P

2006-01-01

Cast nickel-aluminum bronze (NAB) alloy is specified for many marine applications, including ship propellers, due to its excellent corrosion-resistance combined with acceptable mechanical properties...

The inhibition effect and mechanism of L-cysteine on the corrosion of bronze covered with a CuCl patina

International Nuclear Information System (INIS)

Wang, Tianran; Wang, Julin; Wu, Yuqing

2015-01-01

Highlights: • CuCl patina was synthesized on bronze electrodes with electrochemical method. • L-cysteine was used as a green inhibitor for bronze covered with CuCl patina. • The inhibition efficiency reached above 90%. • The inhibition mechanism of L-cysteine on CuCl patina was investigated. - Abstract: CuCl patina was synthesized on bronze electrodes with electrochemical method. The inhibition effect and mechanism of L-cysteine (Cys) on bronze covered with CuCl patina have been studied with electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) techniques. The EIS results show that Cys stabilized the CuCl patina to a great extent. The hydrolysis reaction of CuCl was inhibited effectively and an inhibition efficiency of over 90% was achieved. The XPS analyses indicate that the chemisorption of Cys molecules on CuCl surface occurred through sulfur atom in thiol and nitrogen atom in amino group

Environmental roots of the late bronze age crisis.

Directory of Open Access Journals (Sweden)

David Kaniewski

Full Text Available The Late Bronze Age world of the Eastern Mediterranean, a rich linkage of Aegean, Egyptian, Syro-Palestinian, and Hittite civilizations, collapsed famously 3200 years ago and has remained one of the mysteries of the ancient world since the event's retrieval began in the late 19(th century AD/CE. Iconic Egyptian bas-reliefs and graphic hieroglyphic and cuneiform texts portray the proximate cause of the collapse as the invasions of the "Peoples-of-the-Sea" at the Nile Delta, the Turkish coast, and down into the heartlands of Syria and Palestine where armies clashed, famine-ravaged cities abandoned, and countrysides depopulated. Here we report palaeoclimate data from Cyprus for the Late Bronze Age crisis, alongside a radiocarbon-based chronology integrating both archaeological and palaeoclimate proxies, which reveal the effects of abrupt climate change-driven famine and causal linkage with the Sea People invasions in Cyprus and Syria. The statistical analysis of proximate and ultimate features of the sequential collapse reveals the relationships of climate-driven famine, sea-borne-invasion, region-wide warfare, and politico-economic collapse, in whose wake new societies and new ideologies were created.

Use your eyes - metallographic versus superficial traces of the crafting of Bronze Age ornaments

DEFF Research Database (Denmark)

Nørgaard, Heide Wrobel

and superficial archaeological examinations can be used to understand prehistoric craft. Furthermore, it will show that with an intensive knowledge about previous scientific investigations the superficial traces preserved can reveal a great amount of information and could talk for themselves. Taking as an example...... the early and middle Bronze Age bronze ornaments from North Germany, superficial traces of the metal crafting process, visible with the naked eye, will be compared with metallographic images. The aim of this presentation is to give an overview over the crafting traces everybody could see (with a bit...

Determination of the elemental composition of copper and bronze objects by neutron activation analysis

International Nuclear Information System (INIS)

Hoelttae, P.; Rosenberg, R.J.

1986-01-01

A method for the elemental analysis of copper and bronze objects is described. Na, Co, Ni, Cu, Zn, As, Ag, Sn, Sb, W, Ir and Au are determined through instrumental neutron activation analysis. Mg, Al, V, Ti and Mn are determined after chemical separation using anionic exchange. The detection limits for a number of other elements are also given. Results for NBS standard reference materials are presented and the results compared with the recommended values. The agreement is good. The results of the analysis of five ancient bronze and two copper objects are presented. (author)

Release of copper from sintered tungsten-bronze shot under different pH conditions and its potential toxicity to aquatic organisms

International Nuclear Information System (INIS)

Thomas, Vernon G.; Santore, Robert C.; McGill, Ian

2007-01-01

Sintered tungsten-bronze is a new substitute for lead shot, and is about to be deposited in and around the wetlands of North America. This material contains copper in the alloyed form of bronze. This in vitro study was performed according to U.S. Fish and Wildlife Service criteria to determine the dissolution rate of copper from the shot, and to assess the toxic risk that it may present to aquatic organisms. The dissolution of copper from tungsten-bronze shot, pure copper shot, and glass beads was measured in a buffered, moderately hard, synthetic water of pH 5.5, 6.6, and 7.8 over a 28-day period. The dissolution of copper from both the control copper shot and the tungsten-bronze shot was affected significantly by the pH of the water and the duration of dissolution (all p values < 0.000). The rate of copper release from tungsten bronze shot was 30 to 50 times lower than that from the copper shot, depending on pH (p < 0.0000). The observed expected environmental concentration of copper released from tungsten-bronze shot after 28 days was 0.02 μg/L at pH 7.8, and 0.4 μg/L at pH 5.6, using a loading and exposure scenario specific in a U.S. Fish and Wildlife Service protocol. Ratio Quotient values derived from the highest EEC observed in this study (0.4 μg/L), and the copper toxic effect levels for all aquatic species listed in the U.S. Environmental Protection Agency ambient water quality criteria database, were all far less than the 0.1 criterion value. Given the conditions stipulated by the U.S. Fish and Wildlife Service and the U.S. Environmental Protection Agency, heavy loading from discharged tungsten-bronze shot would not pose a toxic risk to potable water, or to soil. Consequently, it would appear that no toxic risks to aquatic organisms will attend the use of tungsten-bronze shot of the approved composition. Given the likelihood that sintered tungsten-bronze of the same formula will be used for fishing weights, bullets, and wheel balance weights, it is

Tetragonal BiFeO3 on yttria-stabilized zirconia

International Nuclear Information System (INIS)

Liu, Heng-Jui; Du, Yu-Hao; Gao, Peng; Ikuhara, Yuichi; Huang, Yen-Chin; Chen, Yi-Chun; Chen, Hsiao-Wen; Liu, Hsiang-Lin; He, Qing; Chu, Ying-Hao

2015-01-01

High structural susceptibility of multiferroic BiFeO 3 (BFO) makes it a potential replacement of current Pb-based piezoelectrics. In this study, a tetragonal phase is identified based on a combination of x-ray diffraction, scanning transmission electronic microscopy, x-ray absorption spectroscopy, and Raman spectroscopy when BFO is grown on yttria-stabilized zirconia (YSZ) substrates. To distinguish the discrepancy between this tetragonal phase and common cases of monoclinic BFO, piezoelectric force microscopy images and optical property are also performed. It shows a lower electrostatic energy of ferroelectric domains and a large reduction of band gap for BFO grown on YSZ substrate comparing to the well-known one grown on LaAlO 3 substrate. Our findings in this work can provide more insights to understand the structural diversity of multiferroic BFO system for further applications

Non-invasive PGAA, PIXE and ToF-ND analyses on Hungarian Bronze Age defensive armour

International Nuclear Information System (INIS)

Marianne Moedlinger; Imre Kovacs; Zoltan Szoekefalvi-Nagy; Ziad El Morr

2014-01-01

Non-invasive, archaeometric analyses on selected Hungarian Bronze Age defensive armour is presented here: three greaves, three helmets two shields as well as one vessel fragment were analysed with PIXE, PGAA and TOF-ND. The detected alloy elemental and phase composition as well as its intergranular or spatial concentration distribution reveals important insights into the alloys used and the manufacturing techniques applied c. 1200-950 BC, and allows to reconstruct the production techniques used during the Late Bronze Age. (author)

7 CFR 51.1145 - U.S. No. 1 Bronze.

Science.gov (United States)

2010-01-01

...) Internal quality: Lots meeting the internal requirements for “U.S. Grade AA Juice (Double A)” or “U.S... 7 Agriculture 2 2010-01-01 2010-01-01 false U.S. No. 1 Bronze. 51.1145 Section 51.1145 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...

Study on acoustical properties of sintered bronze porous material for transient exhaust noise of pneumatic system

Science.gov (United States)

Li, Jingxiang; Zhao, Shengdun; Ishihara, Kunihiko

2013-05-01

A novel approach is presented to study the acoustical properties of sintered bronze material, especially used to suppress the transient noise generated by the pneumatic exhaust of pneumatic friction clutch and brake (PFC/B) systems. The transient exhaust noise is impulsive and harmful due to the large sound pressure level (SPL) that has high-frequency. In this paper, the exhaust noise is related to the transient impulsive exhaust, which is described by a one-dimensional aerodynamic model combining with a pressure drop expression of the Ergun equation. A relation of flow parameters and sound source is set up. Additionally, the piston acoustic source approximation of sintered bronze silencer with cylindrical geometry is presented to predict SPL spectrum at a far-field observation point. A semi-phenomenological model is introduced to analyze the sound propagation and reduction in the sintered bronze materials assumed as an equivalent fluid with rigid frame. Experiment results under different initial cylinder pressures are shown to corroborate the validity of the proposed aerodynamic model. In addition, the calculated sound pressures according to the equivalent sound source are compared with the measured noise signals both in time-domain and frequency-domain. Influences of porosity of the sintered bronze material are also discussed.

Medical image registration algorithms assesment Bronze Standard application enactment on grids using the MOTEUR workflow engine

CERN Document Server

Glatard, T; Pennec, X

2006-01-01

Medical image registration is pre-processing needed for many medical image analysis procedures. A very large number of registration algorithms are available today, but their performance is often not known and very difficult to assess due to the lack of gold standard. The Bronze Standard algorithm is a very data and compute intensive statistical approach for quantifying registration algorithms accuracy. In this paper, we describe the Bronze Standard application and we discuss the need for grids to tackle such computations on medical image databases. We demonstrate MOTEUR, a service-based workflow engine optimized for dealing with data intensive applications. MOTEUR eases the enactment of the Bronze Standard and similar applications on the EGEE production grid infrastructure. It is a generic workflow engine, based on current standards and freely available, that can be used to instrument legacy application code at low cost.

Correlation of mechanical properties with nondestructive evaluation of babbitt metal/bronze composite interface

Science.gov (United States)

Ijiri, Y.; Liaw, P. K.; Taszarek, B. J.; Frohlich, S.; Gungor, M. N.

1988-09-01

Interfaces of the babbitt metal-bronze composite were examined ultrasonically and were fractured using the Chalmers test method. It was found that the ultrasonic results correlated with the bond strength, the ductility, and the degree of bonding at the tested interface. Specifically, high ultrasonic reflection percentages were associated with low bond strength, low ductility, and low percentages of bonded regions. The fracture mechanism in the bonded area of the babbitt-bronze interface is related to the presence of the intermetallic compound, Cu6Sn5, at the interface. It is suggested that the non-destructive ultrasonic technique can detect the bond integrity of babbitted metals.

Highly stable aqueous zinc-ion storage using a layered calcium vanadium oxide bronze cathode

Energy Technology Data Exchange (ETDEWEB)

Xia, Chuan; Guo, Jing; Li, Peng; Zhang, Xixiang; Alshareef, Husam N. [Materials Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal (Saudi Arabia)

2018-04-03

Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn{sup 2+} intercalation chemistry, stand out as they can employ high-capacity Zn metal as the anode material. Herein, we report a layered calcium vanadium oxide bronze as the cathode material for aqueous Zn batteries. For the storage of the Zn{sup 2+} ions in the aqueous electrolyte, we demonstrate that the calcium-based bronze structure can deliver a high capacity of 340 mA h g{sup -1} at 0.2 C, good rate capability, and very long cycling life (96 % retention after 3000 cycles at 80 C). Further, we investigate the Zn{sup 2+} storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 W h kg{sup -1} at a power density of 53.4 W kg{sup -1}. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Palaeoethnobotanical Data from the High Mountainous Early Bronze Age Settlement of Tsaghkasar-1 (Mt. Aragats, Armenia)

OpenAIRE

Roman Hovsepyan

2011-01-01

Palaeoethnobotanical investigations suggest that at least part of the Early Bronze Age population of Tsaghkasar was settled and practiced agriculture in the high mountainous zone. People there appear to have cultivated hexa‐ and tetraploid wheats (probably bread wheat and emmer) and barley (possibly hulled). Bronze Age agriculture in the Southern Caucasus differs from earlier and later period when cultivation of pulses, oil‐producing plants, and other plants was common. This emphasis on the c...

Tetragonal To Collapsed Tetragonal Phase Transition In BaFe2As2 and CaFe2As2

International Nuclear Information System (INIS)

Mittal, R.; Mishra, S. K.; Chaplot, S. L.; Ovsyannikov, S. V.; Trots, D. M.; Dubrovinsky, L.; Greenberg, E.; Su, Y.; Brueckel, Th.; Matsuishi, S.; Hosono, H.; Garbarino, G.

2010-01-01

Superconductivity in MFe 2 As 2 (M = Ba, Ca) compounds appears either at a critical doping level at ambient pressure or in the parent compound itself by application of pressure above a critical value. We report high pressure powder x-ray diffractions studies for these compounds at 300 K up to about 56 GPa using membrane diamond anvil cells. The measurements for BaFe 2 As 2 show a new tetragonal to collapsed tetragonal phase transition at about 22 GPa that remains stable upto 56 GPa. CaFe 2 As 2 is already known to transform to collapsed phase at 1.7 GPa at 300 K. Our measurements on CaFe 2 As 2 do not show any post collapsed phase transition on increase of pressure 50 GPa at 300 K. It is important to note that the transition in both compounds occurs when they are compressed to almost the same value of the unit cell volume and attain similar c t /a t ratios. We present a detailed analysis of the pressure dependence and structure phase transitions as well as equation of state in these important FeAs compounds that should be useful in the context of possible superconductivity in the collapsed phase.

Electro-optical properties of tetragonal KNbO 3

Indian Academy of Sciences (India)

Linear electro-optical tensor coefficients and optical susceptibility of tetragonal KNbO3 are calculated using a formalism based on bond charge theory. Results are in close agreement with the experimental data. The covalent Nb–O bonding network comprising the distorted NbO6 octahedral groups in the structure is found to ...

Transition to collapsed tetragonal phase in CaFe2As2 single crystals as seen by 57Fe Mössbauer spectroscopy

Science.gov (United States)

Bud'ko, Sergey L.; Ma, Xiaoming; Tomić, Milan; Ran, Sheng; Valentí, Roser; Canfield, Paul C.

2016-01-01

Temperature dependent measurements of 57Fe Mössbauer spectra on CaFe2As2 single crystals in the tetragonal and collapsed tetragonal phases are reported. Clear features in the temperature dependencies of the isomer shift, relative spectra area, and quadrupole splitting are observed at the transition from the tetragonal to the collapsed tetragonal phase. From the temperature dependent isomer shift and spectral area data, an average stiffening of the phonon modes in the collapsed tetragonal phase is inferred. The quadrupole splitting increases by ˜25 % on cooling from room temperature to ˜100 K in the tetragonal phase and is only weakly temperature dependent at low temperatures in the collapsed tetragonal phase, in agreement with the anisotropic thermal expansion in this material. In order to gain microscopic insight about these measurements, we perform ab initio density functional theory calculations of the electric field gradient and the electron density of CaFe2As2 in both phases. By comparing the experimental data with the calculations we are able to fully characterize the crystal structure of the samples in the collapsed-tetragonal phase through determination of the As z coordinate. Based on the obtained temperature dependent structural data we are able to propose charge saturation of the Fe-As bond region as the mechanism behind the stabilization of the collapsed-tetragonal phase at ambient pressure.

Capital Cities in Late Bronze Age Greater Mesopotamia

OpenAIRE

Carlson, Evan

2017-01-01

This dissertation explores the relationships among founding capital cities, defining state territories, and creating and propagating national identities. In the modern period and deep into history, nascent nations struggling to define themselves and unify diverse states have founded capital cities to embody a national ethos, reveal a shared history, direct the relationship among subjects and government, and differentiate a society from its international peers. In the Late Bronze Age (LBA) (15...

Determination of the elemental composition of copper and bronze objects by neutron activation analysis

International Nuclear Information System (INIS)

Hoelttae, P.; Rosenberg, R.J.

1987-01-01

A method for the elemental analysis of copper and bronze objects is described. Na, Co, Ni, Cu, Zn, As, Ag, Sn, Sb, W, Ir and Au are determined through instrumental neutron activation analysis. Mg, Al, V, Ti and Mn are determined after chemical separation using anionic exchange. The detection limits for a number of other elements are also given. Results for NBS standard reference materials are presented and the results are compared with the recommended values. The agreement is good. The results of the analysis of five ancient bronze and two copper objects are also presented. (author) 3 refs.; 4 tabs

Development and manufacturing of bronze-processed Ta-added Nb3Sn wires for the ITER

International Nuclear Information System (INIS)

Kikuchi, Kenichi; Seidou, Masahiro; Iwaki, Genzou; Sakai, Syuuji; Moriai, Hidezumi; Nishi, Masataka; Yoshida, Kiyoshi; Isono, Takaaki; Tsuji, Hiroshi.

1997-01-01

Development work to produce a high-performance Nb 3 Sn superconducting wire for the center solenoid coil of the ITER was carried out. The effects of concurrently adding Ti and Ta to bronze-processed Nb 3 Sn wires were examined. In addition, a high-Sn-concentration bronze matrix was applied. Then, the relation between hysteresis loss and filament diameter was examined. Moreover, the cause of wire breakage during processing was elucidated. As a result, a reliable manufacturing process for high-performance Nb 3 Sn superconducting wire was established. (author)

Charge-density-wave instabilities expected in monophosphate tungsten bronzes

International Nuclear Information System (INIS)

Canadell, E.; Whangbo, M.

1991-01-01

On the basis of tight-binding band calculations, we examined the electronic structures of the tungsten oxide layers found in the monophosphate tungsten bronze (MPTB) phases. The Fermi surfaces of these MPTB phases consist of five well-nested one- and two-dimensional pieces. We calculated the nesting vectors of these Fermi surfaces and discussed the expected charge-density-wave instabilities

Electrodeposition and corrosion resistance of nanocrystalline white bronze (CuSn) coatings

NARCIS (Netherlands)

Hovestad, A.; Lekka, M.; Willemsen, R.M.R.; Tacken, R.A.; Bonora, P.L.

2008-01-01

For jewellery applications electroplated white bronze (CuSn) was investigated as undercoating for noble metal finishes as alternative to nickel. A strongly acidic plating bath was developed with an organic additive to suppress hydrogen evolution and obtain bright coatings. An electrochemical study

First-principles cluster variation calculations of tetragonal-cubic transition in ZrO2

International Nuclear Information System (INIS)

Mohri, Tetsuo; Chen, Ying; Kiyokane, Naoya

2013-01-01

Highlights: ► Cluster variation method is extended to study displacive transition. ► Electronic structure total energy calculations are performed on ZrO2. ► Tetragonal-cubic transition is studied within the framework of order -disorder transition. -- Abstract: It is attempted to extend the basic idea of continuous displacement cluster variation method (CDCVM) to the study of a displacive phase transition. As a preliminary study, we focus on cubic to tetragonal transition in ZrO 2 in which oxygen atoms on the cubic lattice are displaced alternatively in the opposite direction (upward and downward) along the tetragonal axis. Within the CDCVM, displaced atoms are regarded as different atomic species, and two distinguished atoms, A-oxygen (upward shifting) and B-oxygen (downward shifting), are introduced in the description of the free energy. FLAPW electronic structure total energy calculations are performed to extract effective interaction energies among displaced oxygen atoms, and by combing them with CDCVM, the transition temperature is calculated from the first-principles

Tetragonal zirconia quantum dots in silica matrix prepared by a modified sol-gel protocol

Science.gov (United States)

Verma, Surbhi; Rani, Saruchi; Kumar, Sushil

2018-05-01

Tetragonal zirconia quantum dots (t-ZrO2 QDs) in silica matrix with different compositions ( x)ZrO2-(100 - x)SiO2 were fabricated by a modified sol-gel protocol. Acetylacetone was added as a chelating agent to zirconium propoxide to avoid precipitation. The powders as well as thin films were given thermal treatment at 650, 875 and 1100 °C for 4 h. The silica matrix remained amorphous after thermal treatment and acted as an inert support for zirconia quantum dots. The tetragonal zirconia embedded in silica matrix transformed into monoclinic form due to thermal treatment ≥ 1100 °C. The stability of tetragonal phase of zirconia is found to enhance with increase in silica content. A homogenous dispersion of t-ZrO2 QDs in silica matrix was indicated by the mapping of Zr, Si and O elements obtained from scanning electron microscope with energy dispersive X-ray analyser. The transmission electron images confirmed the formation of tetragonal zirconia quantum dots embedded in silica. The optical band gap of zirconia QDs (3.65-5.58 eV) was found to increase with increase in zirconia content in silica. The red shift of PL emission has been exhibited with increase in zirconia content in silica.

An electron microscopy study of the effect of Ce on plasma sprayed bronze coatings

Science.gov (United States)

Wensheng, Li; Wang, S. C.; Ma, Chao; Zhiping, Wang

2012-07-01

The Cu-Al eutectoid alloy is an excellent material for mould due to its superior low friction. The conventional sand casting technique, however, is not feasible to fabricate high Al bronze because of high hardness and brittleness. Plasma arc spray has been used to produce high Al/Fe bronze coatings for mould. The inherent impurities such as H, O, N, S during the spray, however, may affect the coating's mechanical strength. One approach is to utilise the active rare earth Ce to clean up these impurities. The study is to investigate the effect of Ce on the microstructure, which has few reported in the literature.

Artefact biography 2.0 : the information value of corroded archaeological bronzes

NARCIS (Netherlands)

Nienhuis, J.

2017-01-01

The different phases in the life of archaeological objects can be described by artefact biography. This dissertation defines an updated version: artefact biography 2.0, and the life phases of Early Iron Age bronze studs from Oss-Zevenbergen, the Netherlands, are elaborated. Throughout the thesis,

Tetragonal BiFeO{sub 3} on yttria-stabilized zirconia

Energy Technology Data Exchange (ETDEWEB)

Liu, Heng-Jui [Department of Materials Science Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China); Du, Yu-Hao [Department of Materials Science Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Gao, Peng; Ikuhara, Yuichi [Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656 (Japan); Huang, Yen-Chin; Chen, Yi-Chun [Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan (China); Chen, Hsiao-Wen; Liu, Hsiang-Lin [Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China); He, Qing [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Chu, Ying-Hao, E-mail: yhc@nctu.edu.tw [Department of Materials Science Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China)

2015-11-01

High structural susceptibility of multiferroic BiFeO{sub 3} (BFO) makes it a potential replacement of current Pb-based piezoelectrics. In this study, a tetragonal phase is identified based on a combination of x-ray diffraction, scanning transmission electronic microscopy, x-ray absorption spectroscopy, and Raman spectroscopy when BFO is grown on yttria-stabilized zirconia (YSZ) substrates. To distinguish the discrepancy between this tetragonal phase and common cases of monoclinic BFO, piezoelectric force microscopy images and optical property are also performed. It shows a lower electrostatic energy of ferroelectric domains and a large reduction of band gap for BFO grown on YSZ substrate comparing to the well-known one grown on LaAlO{sub 3} substrate. Our findings in this work can provide more insights to understand the structural diversity of multiferroic BFO system for further applications.

Corrosion characteristics of copper and leaded bronze in palm biodiesel

Energy Technology Data Exchange (ETDEWEB)

Haseeb, A.S.M.A.; Masjuki, H.H.; Ann, L.J.; Fazal, M.A. [Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2010-03-15

Biodiesel has become more attractive as alternative fuel for automobiles because of its environmental benefits and the fact that it is made from renewable sources. However, corrosion of metals in biodiesel is one of the concerns related to biodiesel compatibility issues. This study aims to characterize the corrosion behavior of commercial pure copper and leaded bronze commonly encountered in the automotive fuel system in diesel engine. Static immersion tests in B0, B50 and B100 fuels were carried out at room temperature for 2640 h. Similar immersion tests in B0, B100 and B100 (oxidized) fuels were also conducted at 60 C for 840 h. At the end of the test, corrosion behavior was investigated by weight loss measurements and changes in surface morphology. Fuels were analyzed by using TAN analyzer, FTIR, MOA (multi-element oil analyzer) to investigate acid concentration, oxidation level with water content and corrosive impurities respectively. Results showed that under the experimental conditions, pure copper was more susceptible to corrosion in biodiesel as compared to leaded bronze. (author)

Radiocarbon dating of ancient bronze statues: Preliminary results from the Riace statues

International Nuclear Information System (INIS)

Calcagnile, L.; D'Elia, M.; Quarta, G.; Vidale, M.

2010-01-01

The low amount of material needed for the measurements makes AMS radiocarbon a technique suitable for the dating of ancient bronze artefacts through the analysis of the organic residues contained into the casting cores. We present the results of the AMS radiocarbon dating analyses carried out on the organic remains extracted from the casting cores of the Riace bronzes, among the most famous and well preserved sculptures of the Greek-Classical period. Although different dating hypotheses have been suggested on the base of stylistic considerations, no conclusive answers are, so far, available. The sample selection and preparation protocols of the different kind of organic materials (charred wood, vegetal remains and animal hairs) are described as well as the interpretation of the results in the frame of the current dating hypotheses and available analytical information about the casting technology.

The influence of wall thickness on the microstructure of bronze BA1055 with the additions of Si, Cr, Mo and/or W

Directory of Open Access Journals (Sweden)

B.P. Pisarek

2008-12-01

Full Text Available Aluminium bronzes belong to the high-grade constructional materials applied on the put under strongly load pieces of machines, about good sliding, resistant properties on corrosion both in the cast state how and after the thermal processing. It moves to them Cr and Si in the aim of the improvement of their usable proprieties. Additions Mo and/or W were not applied so far in the larger concentration, these elements were introduced to the melts of the copper as the components of modifiers. It was worked out therefore the new kind of bronzes casting including these elements. Make additions to the Cu-Al-Fe-Ni bronze of Si, Cr, Mo and/or W in the rise of these properties makes possible. The investigations of the influence of the wall thickness of the cast on size of crystallites were conducted: the primary phase β and intermetallic phase κ and the width separates of the secondary phase α precipitate at phase boundary. It results from conducted investigations, that in the aluminium bronze BA1055 after simultaneous makes additions Si, Cr, Mo and in the primary phase β it undergoes considerable reducing size. The addition W reduce size of the grain phase β in the thin walls of the cast 3-6 mm, and addition Cr in the range of the thickness of the wall of the cast 3-6 mm it favors to reducing size the phase β, in walls 12-25 mm the growth causes it. The addition Mo does not influence the change of the size of the grain of the β phase significantly. The make addition singly or simultaneously of the Cr, Mo and W to the bronze CuAl10Fe5Ni5Si it influences the decrease of the quantity separates of the phase α on the interface boundary and of width it separates independently from the thickness of the wall of the cast. The simultaneous make addition of the Si, Cr, Mo and W it enlarges the surface of the phase κFe, κMo. The make addition to the bronze CuAl10Fe5Ni5Si of the Cr, Mo or W the quantity of crystallizing hard phase κ enlarges and the

Evaluation of some non-toxic thiadiazole derivatives as bronze corrosion inhibitors in aqueous solution

International Nuclear Information System (INIS)

Varvara, Simona; Muresan, Liana Maria; Rahmouni, Kamal; Takenouti, Hisasi

2008-01-01

The inhibiting effect of four innoxious thiadiazole derivatives (2-mercapto-5-amino-1,3,4-thiadiazole (MAT), 2-mercapto-5-acetylamino-1,3,4-thiadiazole (MAcAT), 2-mercapto-5-methyl-1,3,4-thiadiazole (MMeT) and 2-mercapto-5-phenylamino-1,3,4-thiadiazole (MPhAT)) on bronze corrosion in an aerated solution of 0.2 g L -1 Na 2 SO 4 + 0.2 g L -1 NaHCO 3 at pH 5 was studied by potentiodynamic voltammetry and electrochemical impedance spectroscopy. The corrosion parameters determined from the polarisation curves indicate that the addition of the investigated thiadiazole derivatives decreases both cathodic and anodic current densities, due to an inhibition of the corrosion process, through the adsorption of thiadiazoles on the bronze surface. The inhibiting effect of the investigated organic compounds appears to be more pronounced on the anodic process than on the cathodic one and, except for the case MPhAT, it is enhanced by the increases of the inhibitors' concentration. The adsorption of the thiadiazole derivatives on bronze was confirmed by the presence of the nitrogen atoms in the EDX spectra of the bronze exposed to inhibitor-containing solutions. The magnitude of polarisation resistance values and, consequently, the inhibition efficiencies are influenced by the molecular structure of thiadiazole derivatives. The strongest inhibition was noticed in the presence of compounds with phenyl amino- or amino-functionalities in their molecules. The maximum protection efficiencies were obtained by addition of: 5 mM MAT (95.9%), 1 mM MAcAT (95.7%), 5 mM MMeT (92.6%) and 0.1 mM MPhAT (97%). EIS measurements also revealed that the inhibitor effectiveness of the optimal concentrations of thiadiazole is time-dependent

Evaluation of some non-toxic thiadiazole derivatives as bronze corrosion inhibitors in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Varvara, Simona [Department of Topography, ' 1 Decembrie 1918' University, 11-13 Nicolae Iorga Street, 510009 Alba Iulia (Romania); Muresan, Liana Maria [Department of Physical Chemistry, ' Babes-Bolyai' University, 11 Arany-Janos Street, 400028 Cluj-Napoca (Romania)], E-mail: limur@chem.ubbcluj.ro; Rahmouni, Kamal; Takenouti, Hisasi [UPMC LISE - UPR 15 of the CNRS, ' Pierre and Marie Curie' University, Paris (France)

2008-09-15

The inhibiting effect of four innoxious thiadiazole derivatives (2-mercapto-5-amino-1,3,4-thiadiazole (MAT), 2-mercapto-5-acetylamino-1,3,4-thiadiazole (MAcAT), 2-mercapto-5-methyl-1,3,4-thiadiazole (MMeT) and 2-mercapto-5-phenylamino-1,3,4-thiadiazole (MPhAT)) on bronze corrosion in an aerated solution of 0.2 g L{sup -1} Na{sub 2}SO{sub 4} + 0.2 g L{sup -1} NaHCO{sub 3} at pH 5 was studied by potentiodynamic voltammetry and electrochemical impedance spectroscopy. The corrosion parameters determined from the polarisation curves indicate that the addition of the investigated thiadiazole derivatives decreases both cathodic and anodic current densities, due to an inhibition of the corrosion process, through the adsorption of thiadiazoles on the bronze surface. The inhibiting effect of the investigated organic compounds appears to be more pronounced on the anodic process than on the cathodic one and, except for the case MPhAT, it is enhanced by the increases of the inhibitors' concentration. The adsorption of the thiadiazole derivatives on bronze was confirmed by the presence of the nitrogen atoms in the EDX spectra of the bronze exposed to inhibitor-containing solutions. The magnitude of polarisation resistance values and, consequently, the inhibition efficiencies are influenced by the molecular structure of thiadiazole derivatives. The strongest inhibition was noticed in the presence of compounds with phenyl amino- or amino-functionalities in their molecules. The maximum protection efficiencies were obtained by addition of: 5 mM MAT (95.9%), 1 mM MAcAT (95.7%), 5 mM MMeT (92.6%) and 0.1 mM MPhAT (97%). EIS measurements also revealed that the inhibitor effectiveness of the optimal concentrations of thiadiazole is time-dependent.

Metal Adornments of Clothing and Headwear in the Bronze Age of Western Siberia (issues of research and reconstruction ..

Directory of Open Access Journals (Sweden)

Umerenkova Olga V.

2017-09-01

Full Text Available The article considers issues related to the principals of scientific approach, methods and procedure of costume reconstruction on the basis of archaeological materials dating back to the Bronze Age discovered in the territory of Western Siberia. The costume is considered by researchers as one of the brightest manifestations of material culture. Its decoration provides multidisciplinary information containing elements of ideology and aesthetic norms together with traditions and social relationships. Reconstruction of clothing and headwear adornments in archaeological literature related to the Bronze Age is one of the understudied topics. Researchers use various sources for its recreation: archaeological materials, written historical, literature and folklore sources, and fine art items. A significant amount of source items has accumulated over the last decades, although the analysis and principles of processing thereof have not been sufficiently covered in special literature. In order to increase the informative capabilities of adornments as sources for the reconstruction of the Bronze Age costume, the author suggested a scheme of accounting for the location of adornments with respect to the remains of the buried when the excavations are documented. The article features the results of the author's reconstruction of women's headwear decoration with metal articles executed on the basis of Bronze Age materials.

Investigation of vanadium oxide bronzes of phase β by means of annihilation of positrons

International Nuclear Information System (INIS)

Dryzek, E.

1992-01-01

The vanadium bronzes with general composition M x V 2 O 5 (where M means the donor element Li, Na, K, Cu, Na) have been the object of the investigation. The positron annihilation method as well as the broadening of the annihilation line in Doppler spectra have been the basing methods for the study of material structure. The donor lattice vacancies have been investigated as a positron traps being responsible for the shape of annihilation spectra. The model of clustering of donor ions has been constructed. On that base and temperature dependence of the positron annihilation spectra the thermodynamical parameters of donor ion vacancies in vanadium bronzes have been calculated. 112 refs, 33 figs, 11 tabs

Cold spraying of aluminum bronze on profiled submillimeter cermet structures formed by laser cladding

Science.gov (United States)

Ryashin, N. S.; Malikov, A. G.; Shikalov, V. S.; Gulyaev, I. P.; Kuchumov, B. M.; Klinkov, S. V.; Kosarev, V. F.; Orishich, A. M.

2017-10-01

The paper presents results of the cold spraying of aluminum bronze coatings on substrates profiled with WC/Ni tracks obtained by laser cladding. Reinforcing cermet frames shaped as grids with varied mesh sizes were clad on stainless steel substrates using a CO2 laser machine "Siberia" (ITAM SB RAS, Russia). As a result, surfaces/substrates with heterogeneous shape, composition, and mechanical properties were obtained. Aluminum bronze coatings were deposited from 5lF-NS powder (Oerlikon Metco, Switzerland) on those substrates using cold spraying equipment (ITAM SB RAS). Data of profiling, microstructure diagnostics, EDS analysis, and mechanical tests of obtained composites is reported. Surface relief of the sprayed coatings dependence on substrate structure has been demonstrated.

Study on effect of cubic- and tetragonal phased BaTiO{sub 3} on the electrical and thermal properties of polymeric nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Thanki, A.A.; Goyal, R.K., E-mail: rkgoyal72@yahoo.co.in

2016-11-01

Polymer matrix nanocomposites based on polycarbonate (PC) and nanosized-cubic/tetragonal phases of barium titanate (BaTiO{sub 3}) were fabricated using a solution method followed by hot pressing. The content of both cubic- and tetragonal phased BaTiO{sub 3} was varied from 0 to 50 wt%. For a given weight fraction, the dielectric constant of the nanocomposites containing tetragonal BaTiO{sub 3} is more than those of cubic BaTiO{sub 3} filled nanocomposites. Moreover, cubic BaTiO{sub 3}/PC nanocomposites showed significantly lower dissipation factor than those of tetragonal BaTiO{sub 3}/PC nanocomposites. The dielectric constant of the nanocomposites was found to be frequency-independent. The microhardness of the nanocomposites increased with increase in the BaTiO{sub 3} content (both cubic- and tetragonal-phased) compared to the pure matrix. Scanning electron microscopy showed better dispersion and good interaction of the tetragonal BaTiO{sub 3} nanoparticles in the matrix. The addition of cubic BaTiO{sub 3} nanoparticles significantly reduced the thermal stability of the nanocomposites compared to matrix while the addition of tetragonal BaTiO{sub 3} nanoparticles decreased it slightly. The glass transition temperature of the cubic BaTiO{sub 3}/PC nanocomposites decreased significantly, whereas it reduced slightly for the tetragonal BaTiO{sub 3}/PC nanocomposites. - Highlights: • The effect of cubic-BaTiO{sub 3} and tetragonal-BaTiO{sub 3} nanoparticles were studied. • Cubic-BaTiO{sub 3} nanoparticles showed better microhardness. • Tetragonal-BaTiO{sub 3} nanoparticles showed better dielectric and thermal properties. • Frequency independent dielectric constants of the nanocomposites were observed.

NUMERICAL MODELING OF HARDENING OF UNINTERRUPTEDLY-CASTED BRONZE CASTING

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E. I. Marukovich

2009-01-01

Full Text Available The three-dimensional numerical model for calculation of thermal fields during solidification of continuously casted bronze casting is developed. Coefficients of heat transfer on borders of calculation areas on the basis of the solution of inverse heat transfer conduction problem are determined. The analysis of thermal fields, depending on loop variables of drawing and the sizes of not cooled zone of crystallizer is curried out.

Bronze-mean hexagonal quasicrystal

Science.gov (United States)

Dotera, Tomonari; Bekku, Shinichi; Ziherl, Primož

2017-10-01

The most striking feature of conventional quasicrystals is their non-traditional symmetry characterized by icosahedral, dodecagonal, decagonal or octagonal axes. The symmetry and the aperiodicity of these materials stem from an irrational ratio of two or more length scales controlling their structure, the best-known examples being the Penrose and the Ammann-Beenker tiling as two-dimensional models related to the golden and the silver mean, respectively. Surprisingly, no other metallic-mean tilings have been discovered so far. Here we propose a self-similar bronze-mean hexagonal pattern, which may be viewed as a projection of a higher-dimensional periodic lattice with a Koch-like snowflake projection window. We use numerical simulations to demonstrate that a disordered variant of this quasicrystal can be materialized in soft polymeric colloidal particles with a core-shell architecture. Moreover, by varying the geometry of the pattern we generate a continuous sequence of structures, which provide an alternative interpretation of quasicrystalline approximants observed in several metal-silicon alloys.

Influence of heating rates on in situ resistance measurements of a bronze route Nb-Sn-Cu-Ta multifilamentary conductor

International Nuclear Information System (INIS)

Tan, K.S.; Hopkins, S.C.; Glowacki, B.A.

2004-01-01

The superconducting properties of a bronze process multifilamentary conductor are controlled by the structure, dimensions and composition of the intermetallic layers, which are strongly influenced by the details of the heat treatments applied to the conductor. It has previously been reported that the electrical resistivity of a Vacuumschmelze bronze process conductor varies during heat treatment, and that analysis of the conductor as a set of parallel resistors allows the features of the resistivity variation to be assigned to the progress of Nb 3 Sn intermetallic phase formation. The behaviour of NSP2 Nb-Sn-Cu-Ta bronze process multifilamentary conductors (Imperial Metal Industries) is now reported as a function of the heating rate, in preparation for more complex non-isothermal heat treatment procedures. It is shown that the resistance of the wire measured in situ by an alternating current (AC) technique can be used to observe the progress of the formation of Nb 3 Sn, and that the comparison of resistometric measurements at different heating rates can give an indication of other processes (such as recovery and recrystallisation) occurring at lower temperatures during the heating up process prior to isothermal annealing. In addition, this wire containing only about 1% of copper was carefully chosen because of the broken tantalum barriers around individual copper filaments. Therefore, the resistometric measurements were used to attempt to detect the diffusion of tin from the bronze matrix into the copper filaments at lower temperatures without noticeable influence on Nb 3 Sn phase formation. Treating the NSP2 wire as a set of parallel resistors also permits estimates to be made of the intermetallic layer thicknesses from resistometric measurements, and these are shown to be in good agreement with estimates from scanning electron microscopy. The difference in critical temperature, T c , between wires heated at different rates, with the presence of the bronze matrix

Copper and tin isotopic analysis of ancient bronzes for archaeological investigation: development and validation of a suitable analytical methodology.

Science.gov (United States)

Balliana, Eleonora; Aramendía, Maite; Resano, Martin; Barbante, Carlo; Vanhaecke, Frank

2013-03-01

Although in many cases Pb isotopic analysis can be relied on for provenance determination of ancient bronzes, sometimes the use of "non-traditional" isotopic systems, such as those of Cu and Sn, is required. The work reported on in this paper aimed at revising the methodology for Cu and Sn isotope ratio measurements in archaeological bronzes via optimization of the analytical procedures in terms of sample pre-treatment, measurement protocol, precision, and analytical uncertainty. For Cu isotopic analysis, both Zn and Ni were investigated for their merit as internal standard (IS) relied on for mass bias correction. The use of Ni as IS seems to be the most robust approach as Ni is less prone to contamination, has a lower abundance in bronzes and an ionization potential similar to that of Cu, and provides slightly better reproducibility values when applied to NIST SRM 976 Cu isotopic reference material. The possibility of carrying out direct isotopic analysis without prior Cu isolation (with AG-MP-1 anion exchange resin) was investigated by analysis of CRM IARM 91D bronze reference material, synthetic solutions, and archaeological bronzes. Both procedures (Cu isolation/no Cu isolation) provide similar δ (65)Cu results with similar uncertainty budgets in all cases (±0.02-0.04 per mil in delta units, k = 2, n = 4). Direct isotopic analysis of Cu therefore seems feasible, without evidence of spectral interference or matrix-induced effect on the extent of mass bias. For Sn, a separation protocol relying on TRU-Spec anion exchange resin was optimized, providing a recovery close to 100 % without on-column fractionation. Cu was recovered quantitatively together with the bronze matrix with this isolation protocol. Isotopic analysis of this Cu fraction provides δ (65)Cu results similar to those obtained upon isolation using AG-MP-1 resin. This means that Cu and Sn isotopic analysis of bronze alloys can therefore be carried out after a single chromatographic

Dynamic tensile behaviour and deformational mechanism of C5191 phosphor bronze under high strain rates deformation

Energy Technology Data Exchange (ETDEWEB)

Hu, Dao-chun [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); College of Mechanical and Electrical Engineering, Taizhou Vocational & Technical College, Taizhou 318000 (China); Chen, Ming-he, E-mail: meemhchen@nuaa.edu.cn [College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Lei; Cheng, Hu [College of Mechanical Engineering, Taizhou University, Taizhou 318000 (China)

2016-01-01

High speed stamping process is used to high strength and high electrical conductivity phosphor bronze with extremely high strain rates more than 10{sup 3} s{sup −1}. This study on the dynamic tensile behaviour and deformational mechanism is to optimise the high speed stamping processes and improve geometrical precision in finished products. Thus, the tensile properties and deformation behaviour of C5191 phosphor bronze under quasi-static tensile condition at a strain rate of 0.001 s{sup −1} by electronic universal testing machine, and dynamic tensile condition at strain rate of 500, 1000 and 1500 s{sup −1} by split Hopkinson tensile bar (SHTB) apparatus were studied. The effects of strain rate and the deformation mechanism were investigated by means of SEM and TEM. The results showed that the yield strength and tensile strength of C5191 phosphor bronze under high strain rates deformation increased by 32.77% and 11.07% respectively compared with quasi-static condition, the strain hardening index increases from 0.075 to 0.251, and the strength of the material strain rates sensitivity index change from 0.005 to 0.022, which presented a clear sensitive to strain rates. Therefore, it is claimed that the dominant deformation mechanism was changed by the dislocation motion under different strain rates, and the ability of plastic deformation of C5191 phosphor bronze increased due to the number of movable dislocations increased significantly, started multi-line slip, and the soft effect of adiabatic temperature rise at the strain rate ranging from 500 to 1500 s{sup −1}.

Human paleodiet and animal utilization strategies during the Bronze Age in northwest Yunnan Province, southwest China.

Directory of Open Access Journals (Sweden)

Lele Ren

Full Text Available Reconstructing ancient diets and the use of animals and plants augment our understanding of how humans adapted to different environments. Yunnan Province in southwest China is ecologically and environmentally diverse. During the Neolithic and Bronze Age periods, this region was occupied by a variety of local culture groups with diverse subsistence systems and material culture. In this paper, we obtained carbon (δ13C and nitrogen (δ15N isotopic ratios from human and faunal remains in order to reconstruct human paleodiets and strategies for animal exploitation at the Bronze Age site of Shilinggang (ca. 2500 Cal BP in northwest Yunnan Province. The δ13C results for human samples from Shilinggang demonstrate that people's diets were mainly dominated by C3-based foodstuffs, probably due to both direct consumption of C3 food and as a result of C3 foddering of consumed animals. Auxiliary C4 food signals can also be detected. High δ15N values indicate that meat was an important component of the diet. Analysis of faunal samples indicates that people primarily fed pigs and dogs with human food waste, while sheep/goats and cattle were foddered with other food sources. We compare stable isotope and archaeobotanical data from Shilinggang with data from other Bronze Age sites in Yunnan to explore potential regional variation in subsistence strategies. Our work suggests that people adopted different animal utilization and subsistence strategies in different parts of Yunnan during the Bronze Age period, probably as local adaptations to the highly diversified and isolated environments in the region.

Bronze Jewellery from the Early Iron Age urn-field in Mała Kępa. An approach to casting technology

Directory of Open Access Journals (Sweden)

Garbacz-Klempka A.

2017-09-01

Full Text Available This study characterizes the bronze jewellery recovered from the Lusatian culture urn-field in Mała Kępa (Chełmno land, Poland. Among many common ornaments (e.g. necklaces, rings, pins the ones giving evidence of a steppe-styled inspiration (nail earrings were also identified. With the dendritic microstructures revealed, the nail earrings prove the implementing of a lost-wax casting method, whereas some of the castings were further subjected to metalworking. The elemental composition indicates the application of two main types of bronze alloys: Cu-Sn and Cu-Sn-Pb. It has been established that the Lusatian metalworkers were familiar with re-melting the scrap bronze and made themselves capable of roasting the sulphide-rich ores.

The bronze signum from Timacum Maius and its cultic attribution

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Petrović Vladimir

2016-01-01

Full Text Available The bronze signum discussed in this paper was discovered by archaeological ex­cavation on the site of Timacum Maius in 2010. Found in the area of a luxurious Roman-period building, the artefact shows a tapering body with a central conical socket similar to a spearhead socket. It is one of the twenty-three known signa of the so-called classical-type. Most of them were found in the context of the cult of Jupiter Dolichenus, and we also presume the cultic purpose of the bronze signum from Timacum Maius. A similar find comes from Jupiter Dolichenus’ shrine in Egeta on the Danube limes with an inscription that connects it directly with the Dolichenian cult, and with the First Cohort of Cretans (Cohors I Cretum, the unit which had previously been stationed at Timacus Maius. The signum from Timacum Maius is most likely also connected with the cult of Jupiter Dolichenus and chronologically belongs to a period which is much earlier than the Severan age. [Projekat Ministarstva nauke Republike Srbije, 177012: Society, spiritual and material culture and communications in prehistory and early history of the Balkans

Various magnetic behaviors of the hydrides deriving from the tetragonal CeFeSi-type compounds

International Nuclear Information System (INIS)

Chevalier, B.; Tence, S.; Gaudin, E.; Matar, S.F.; Bobet, J.-L.

2009-01-01

The hydrides RETXH (RE = rare earth, T = transition metal and X = Si, Ge) crystallizing in the tetragonal ZrSiCuAs-type are obtained by hydrogen absorption of the intermetallics adopting the tetragonal CeFeSi-type. The H-insertion induces interesting magnetic transitions governed by two effects: the increase of the unit cell volume linked to the H-absorption and the occurrence of the RE-H chemical bonding. Some typical examples are reported in this present brief review.

Mechanical properties and dependence with temperature of tetragonal polycrystalline zirconia materials

International Nuclear Information System (INIS)

Orange, G.

1986-01-01

Polycrystalline zirconia materials with a high content of metastable tetragonal phase have been obtained by pressureless sintering from experimental powders. Mechanical properties have been determined at room temperature and compared with similar materials. The fracture strength (σ /SUB f/ ) and fracture toughness (K /SUB 1c/ ) temperature dependence has been studied, in air environment up to 1000 0 C. Microstructure was studied by SEM examinations of fracture faces and TEM observations. Fracture toughness (of about 10 MPa √m at room temperature) decreases from 200 0 C to 800 0 C. The critical temperature (T /SUB c/ ) is estimated at 600 0 C. We observe an important decreases of fracture strength at 200 0 C. These mechanical properties are discussed on the basis of the stability of the tetragonal phase depending on additive content, grain size and temperature

Dynamic secondary ion mass spectrometry and X-ray photoelectron spectroscopy on artistic bronze and copper artificial patinas

International Nuclear Information System (INIS)

Balta, I.Z.; Pederzoli, S.; Iacob, E.; Bersani, M.

2009-01-01

To prevent the natural processes of decay and to develop and improve the treatments of conservation and restoration of artistic bronzes meaning statues and sculptures, it is important understanding the patination processes and the knowledge of artificially corroded surfaces. Chemical and physical characterization of artificial patinas obtained on artistic bronzes and coppers by using the 19th century Western traditional patination techniques and recipes by means of SEM-EDS, light microscopy and ATR/FT-IR has been done in previous studies [I.Z. Balta, L. Robbiola, Characterization of artificial black patinas on artistic cast bronze and pure copper by using SEM-EDS and light microscopy, in: Proceedings of the 13th European Microscopy Congress, 22-27 August 2004, Antwerp, Belgium, EMC 2004 CD-Rom Conference Preprints; I.Z. Balta, L. Robbiola, Traditional artificial artistic bronze and copper patinas-an investigation by SEM-EDS and ATR/FT-IR, in: Proceedings of the 8th International Conference on Non Destructive Investigations and Microanalysis for the Diagnostics and Conservation of the Cultural and Environmental Heritage, 15-19 May 2005, Lecce, Italy, ART'05 CD-Rom Conference Preprints]. Differences in morphology (structure, thickness, porosity, adherence, compactity, uniformity, homogeneity) and also in composition, on both artistic cast bronze and pure copper patinas, were clearly evidenced. Further in-depth investigation is required to be carried out in order to better understand the patinas mechanisms of formation and the layers kinetics of growth. The elemental and chemical analysis, either on a surface monolayer or in a depth profile, by using the Secondary Ion Mass Spectrometry (SIMS) and X-ray Photoelectron Spectroscopy (XPS) techniques, can provide this kind of information, unique at trace-level sensitivity. SIMS has proved to be a suitable analytical technique for analyzing small amounts of material with high atomic sensitivity (ppm or even ppb) and high

Dynamic secondary ion mass spectrometry and X-ray photoelectron spectroscopy on artistic bronze and copper artificial patinas

Energy Technology Data Exchange (ETDEWEB)

Balta, I.Z., E-mail: balta_z_i@yahoo.com [National Research Institute for Conservation and Restoration, Calea Victoriei 12, Sector 3, 030026 Bucharest (Romania); Pederzoli, S.; Iacob, E.; Bersani, M. [Fondazione Bruno Kessler - IRST, Centro per la Ricerca Scientifica e Tecnologica, Trento (Italy)

2009-04-01

To prevent the natural processes of decay and to develop and improve the treatments of conservation and restoration of artistic bronzes meaning statues and sculptures, it is important understanding the patination processes and the knowledge of artificially corroded surfaces. Chemical and physical characterization of artificial patinas obtained on artistic bronzes and coppers by using the 19th century Western traditional patination techniques and recipes by means of SEM-EDS, light microscopy and ATR/FT-IR has been done in previous studies [I.Z. Balta, L. Robbiola, Characterization of artificial black patinas on artistic cast bronze and pure copper by using SEM-EDS and light microscopy, in: Proceedings of the 13th European Microscopy Congress, 22-27 August 2004, Antwerp, Belgium, EMC 2004 CD-Rom Conference Preprints; I.Z. Balta, L. Robbiola, Traditional artificial artistic bronze and copper patinas-an investigation by SEM-EDS and ATR/FT-IR, in: Proceedings of the 8th International Conference on Non Destructive Investigations and Microanalysis for the Diagnostics and Conservation of the Cultural and Environmental Heritage, 15-19 May 2005, Lecce, Italy, ART'05 CD-Rom Conference Preprints]. Differences in morphology (structure, thickness, porosity, adherence, compactity, uniformity, homogeneity) and also in composition, on both artistic cast bronze and pure copper patinas, were clearly evidenced. Further in-depth investigation is required to be carried out in order to better understand the patinas mechanisms of formation and the layers kinetics of growth. The elemental and chemical analysis, either on a surface monolayer or in a depth profile, by using the Secondary Ion Mass Spectrometry (SIMS) and X-ray Photoelectron Spectroscopy (XPS) techniques, can provide this kind of information, unique at trace-level sensitivity. SIMS has proved to be a suitable analytical technique for analyzing small amounts of material with high atomic sensitivity (ppm or even ppb) and

Female exogamy and gene pool diversification at the transition from the Final Neolithic to the Early Bronze Age in central Europe.

Science.gov (United States)

Knipper, Corina; Mittnik, Alissa; Massy, Ken; Kociumaka, Catharina; Kucukkalipci, Isil; Maus, Michael; Wittenborn, Fabian; Metz, Stephanie E; Staskiewicz, Anja; Krause, Johannes; Stockhammer, Philipp W

2017-09-19

Human mobility has been vigorously debated as a key factor for the spread of bronze technology and profound changes in burial practices as well as material culture in central Europe at the transition from the Neolithic to the Bronze Age. However, the relevance of individual residential changes and their importance among specific age and sex groups are still poorly understood. Here, we present ancient DNA analysis, stable isotope data of oxygen, and radiogenic isotope ratios of strontium for 84 radiocarbon-dated skeletons from seven archaeological sites of the Late Neolithic Bell Beaker Complex and the Early Bronze Age from the Lech River valley in southern Bavaria, Germany. Complete mitochondrial genomes documented a diversification of maternal lineages over time. The isotope ratios disclosed the majority of the females to be nonlocal, while this is the case for only a few males and subadults. Most nonlocal females arrived in the study area as adults, but we do not detect their offspring among the sampled individuals. The striking patterns of patrilocality and female exogamy prevailed over at least 800 y between about 2500 and 1700 BC. The persisting residential rules and even a direct kinship relation across the transition from the Neolithic to the Bronze Age add to the archaeological evidence of continuing traditions from the Bell Beaker Complex to the Early Bronze Age. The results also attest to female mobility as a driving force for regional and supraregional communication and exchange at the dawn of the European metal ages.

Hydrothermal preparation of blue molybdenum bronze nanoribbons: structural changes in mother crystals, related to solid-state conversion and crystallite splitting to nanomorphology

Science.gov (United States)

Nishida, Takamasa; Eda, Kazuo

2018-02-01

Hydrothermal syntheses of alkali-metal blue molybdenum bronze nanoribbons, which are expected to exhibit unique properties induced by a combined effect of extrinsic and intrinsic low-dimensionalities, from hydrated-alkali-metal molybdenum bronzes were investigated. Nanoribbons grown along the quasi-one-dimensional (1D) conductive direction of Cs0.3MoO3, which is difficult to prepare by the conventional methods, were first synthesized. The nanomorphology formation is achieved by a solid-state conversion (or crystallite splitting) and subsequent crystallite growth, and the structural changes of the starting material related to the conversion were first observed by powder X-ray diffraction and scanning transmission electron microscopy as a result of finely tuned reaction system and preparation conditions. The structural changes were analyzed by model simulations and were attributed to the structural modulations that were concerned with the intralayer packing disorder and with two-dimensional long-range ordered structure, formed in MoO3 sheets of the hydrated molybdenum bronze. Moreover, the modulations were related to displacement defects of the Mo-O framework units generated along the [100] direction in the hydrated molybdenum bronze. Then, it was suggested that the solid-state conversion into blue molybdenum bronze and the crystallite splitting to nanomorphology were initiated by the breaking of the Mo-O-Mo bonds at the defects. [Figure not available: see fulltext.

Microstructure investigation of bronze/steel brazed joints proposed for HHF components of ITER manufacturing

Energy Technology Data Exchange (ETDEWEB)

Kalinin, G.M. [Research and Development Institute of Power Engineering, P.O. Box 788, Moscow 101000 (Russian Federation)], E-mail: gmk@nikiet.ru; Krestnikov, N.S. [Research and Development Institute of Power Engineering, P.O. Box 788, Moscow 101000 (Russian Federation); Jarovinskiy, Yu.L.; Makhin, I.D.; Nikolaev, V.V. [Rocket and Space Corporation ' Energia' , Korolev, Lenina Street 4-a, Moscow 141070 (Russian Federation); Skladnov, K.S.; Strebkov, Yu.S.; Zolotarev, V.B. [Research and Development Institute of Power Engineering, P.O. Box 788, Moscow 101000 (Russian Federation)

2008-12-15

Brazing is considered as one of the perspective option of high heat flux components of ITER manufacturing. CuCrZr bronze, austenitic steel AISI 321-type and PM-17-type (Ni-Mn-Fe-Si-Sn-B alloy) brazed material were used for the development of brazing technology. Two type of brazing have been studied within the framework of recent investigation: - Hot isostatic pressing (HIP)-assisted brazing. - Furnace-assisted brazing (with uniaxial compression loading). For the hydrostatic pressing (HIP) the brazed components were pressed out for about 175 MPa during 2.5 h at the temperature 1035-1040 deg. C. For the furnace-assisted brazing all components were inserted into the sealed can, vacuumed and heated up to brazing temperature {approx}950 deg. C. Fast cooling and ageing heat treatment (500 deg. C and 4 h) were applied to provide high strength of CuCrZr bronze. Microsections of specimens cut from the joints were studied by optical microscopy and by scanning electron microscopy (SEM). The microstructure, distribution of alloying elements of base metals and of brazed material components were studied in the joints. Results of these studies are discussed in this paper. The data shows that there is a potential for using more simple and cheap (in comparison with common HIP) technologies of bronze to steel joining with satisfactory quality.

Computed Tomography and Computed Radiography of late Bronze Age Cremation Urns from Denmark

DEFF Research Database (Denmark)

Harvig, Lise Lock; Lynnerup, Niels; Amsgaard Ebsen, Jannie

2012-01-01

To improve methods used to study prehistoric cremation rituals, cremation urns from the Danish late Bronze Age were examined using Computed Tomography and Computed Radiography (Digital X-ray). During microexcavation, the digital images were used as registration tool. Our results suggest...

Micro-EDXRF surface analyses of a bronze spear head: Lead content in metal and corrosion layers

International Nuclear Information System (INIS)

Figueiredo, E.; Valerio, P.; Araujo, M.F.; Senna-Martinez, J.C.

2007-01-01

A bronze spear head from Central Portugal dated to Late Bronze Age has been analyzed by non-destructive micro-EDXRF in the metal surface and corrosion layers. The artifact had previously been analyzed using a conventional EDXRF spectrometer having a larger incident beam. The quantification of the micro-EDXRF analyses showed that lead content in corrosion layers can reach values up to four times higher than the content determined in the metal surface. Results obtained with the higher energy incident beam from the EDXRF equipment, although referring mainly to the corrosion layers, seem to suffer some influence from the surface composition of the metallic alloy

Linear electro-optical properties of tetragonal BaTiO 3

Indian Academy of Sciences (India)

Linear optical susceptibility and clamped linear electro-optical tensor coefficients of tetragonal BaTiO3 are calculated using a formalism based on bond charge theory. Calculated values are in close agreement with experimental data. The covalent Ti–O bonds constituting distorted TiO6 octahedral groups are found to be ...

Joining of rubber substrate with bronze surface by the method of molecular adhesion

International Nuclear Information System (INIS)

Oravec, J.; Preto, J.; Hronkovic, J.; Melus, P.; Hirahara, H.; Sang, J.

2017-01-01

During the adhesion process using the adhesives there are many risks of defects caused by boundary stress, strength and to resolve these traditional adhesive problems a method called molecule adhesion technology, was used. This method can successfully adhere different materials and has the advantages such as material independence and strong adhesion strength without any adhesive agent. The impact of selected coupling agents on the green and final adhesion on the boundary bronze surface - natural rubber based coating blend was studied in the presented work. Wires of bronze (Cu/Sn 96:4) coated steel bead wire were submerged in solutions of coupling agents in ethanol for 30 s at various temperature and dried. The effect of the surface modification was evaluated by measuring of XPS, FT-IR, the morphology of the brass plate surfaces after the treatment was studied by the atomic force microscopy (AFM). (authors)

Neutron and X-ray characterisation of the metallurgical properties of a 7th century BC Corinthian-type bronze helmet

Science.gov (United States)

Pantos, E.; Kockelmann, W.; Chapon, L. C.; Lutterotti, L.; Bennet, S. L.; Tobin, M. J.; Mosselmans, J. F. W.; Pradell, T.; Salvado, N.; Butí, S.; Garner, R.; Prag, A. J. N. W.

2005-09-01

Neutron and synchrotron X-ray diffraction, X-ray fluorescence and FTIR were used to examine a Corinthian-type bronze helmet which is now on display at The Manchester Museum, UK. This type of helmet was manufactured out of a single piece of bronze, probably on a rod-anvil, and like all body-armour it was made to measure. Neutron diffraction sampling of the bronze volume in different areas was used to study the composition, microstructure and crystallographic texture of the alloy in order to draw conclusions about the manufacturing processes. The neutron data revealed the presence of microstrains and non-random distributions of bronze grains hinting at annealing-hammering working cycles in order to harden and shape the alloy. X-ray fluorescence showed that the main body of the helmet is a copper-tin alloy, while the noseguard contains zinc in high abundance. This key compositional difference confirms that the noseguard is not the original but is a modern substitute fabricated for restoration purposes. SR XRD and FTIR from several spots on the head and noseguard identified several surface corrosion products and showed a variation of the Cu-Sn or Cu-Zn percentage compositions, and of the mineral phases. Small samples of corrosion flakes extracted from the outside and inside of the helmet were used to obtain powder XRD patterns.

HANDICRAFT IN LATE BRONZE-EARLY IRON AGE IN NAKHCHIVAN

OpenAIRE

Toğrul HALİLOV

2012-01-01

The article handicraft have been learnt in the Nakhchivan late bronze-early iron age. It was defined that pottery wasone of the ancient craftsmanship areas in Nakhichivan. At that time Nakhichivan, as well as the other regions of Azerbaijan, was an important centre of craftsmanship. The pottery products differed from one another in their size, shape, ornaments on them, the material the were made of and the technology. The pottery products made by Nakhichivan potters were divided into two grou...

Specific corrosion product on interior surface of a bronze wine vessel with loop-handle and its growth mechanism, Shang Dynasty, China

International Nuclear Information System (INIS)

Li Yang; Bao Zhirong; Wu Taotao; Jiang, Junchun; Chen Guantao; Pan Chunxu

2012-01-01

In this paper, a kind of specific stalactitic product was found on the interior surface of a covered bronze wine vessel with loop-handle (Chinese name is you), which was fabricated in Shang Dynasty (1700 B.C.–1100 B.C.) and now is collected in Xiaogan Museum, Hubei province of China. The microstructures of the product were characterized systematically by using optical microscopy, scanning electron microscope, transmission electron microscope, X-ray diffraction, and Raman microscopy. The experimental results revealed that the product belonged to a kind of malachite with high purity and high crystallinity. The growth of the product was considered to be a possible reason that the vessel was overly airtight within a museum display cabinet besides a lid of the vessel, which made the excess of H 2 O and CO 2 gas concentrations inside the vessel during long-term storage. This corrosion product is very harmful to bronze cultural relics, because of a large amount of copper consumption from the matrix which will reduce its life. The growth mechanism of the specific stalactitic product and the suggestions for preservation of the similar bronze relics in museum were proposed. - Highlights: ► The stalactitic product was the high purity and good crystallinity malachite. ► Its growth was related to the excess of H 2 O and CO 2 gas concentrations in museum. ► It is harmful to the bronzes, because copper will be consumed from the matrix. ► The suggestions for preservation of the similar bronzes in museum were proposed.

Off-center Jahn-Teller ion: coupled polar and tetragonal deformations

International Nuclear Information System (INIS)

Vikhnin, V.S.; Sochava, L.S.

1979-01-01

Models of the off-center Jahn-Teller ions are considered, i.e. Ni + in SrO and Cu 27 in SrO studied earlier. Models of the off-center Jahn-Teller ion are proposed, in which mutual effect of dipole-active deformations conditioning off-centering and the Jahn-Teller tetragonal deformations takes place. Manifestations of a new type of multipit potential XY 24 of an off-center ion are considered. The Jahn-Teller effect (JTE) is studied for a duplicate in cubic environment, unharmonism of the fourth order being taken into account. In such a model of Exe of JTE, the position and quantity of minima of adiabatic potential are changed as compared with Exe of JTE taking account of unharmonism of the third order or the square Jahn-Teller interaction. While using models of the off-center Jahn-Teller ion which take account of the effect of two tetragonal Jahn-Teller deformations occurring in the Exe problem considering unharmonism of the fourth order produced on dipole-active deformations, it becomes possible to explain the experiment for SrO:Ni +

Chipped Stone Industry of the Moravian Early Bronze Age – Typological Considerations

Czech Academy of Sciences Publication Activity Database

Kopacz, J.; Matějka, František; Matějková, Jiřina; Přichystal, A.; Škrdla, Petr; Šebela, Lubomír

2006-01-01

Roč. 2, - (2006), s. 95-117. ISBN 80-7248-395-1. ISSN N R&D Projects: GA AV ČR(CZ) IAA8001202 Institutional research plan: CEZ:AV0Z80010507; CEZ:AV0Z20650511 Keywords : Early Bronze Age * Moravia * stone chipped industry, segment Subject RIV: AC - Archeology, Anthropology, Ethnology

Ancient bronze coins from Mediterranean basin: LAMQS potentiality for lead isotopes comparative analysis with former mineral

Energy Technology Data Exchange (ETDEWEB)

Torrisi, L., E-mail: Lorenzo.Torrisi@unime.it [Department of Physics Science - MIFT, Messina University, V.le F.S. d’Alcontres 31, 98166 S. Agata, Messina (Italy); Italiano, A. [INFN, Sezione di Catania, Gruppo collegato di Messina (Italy); Torrisi, A. [Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Str., 00-908 Warsaw (Poland)

2016-11-30

Highlights: • Surface and bulk compositional elements in ancient bronze coins were investigated using XRF analysis. • Lead stable isotope {sup 204}Pb, {sup 206}Pb, {sup 207}Pb and {sup 208}Pb were measured in ancient coins with LAMQS analysis. • Lead ratios {sup 208}Pb/{sup 206}Pb and {sup 207}Pb/{sup 206}Pb, measured by LAMQS, were compared with Brettscaife.net geological database relative to the minerals in different mines of Mediterranean basin. • Bronze coins were correlated to possible ancient mining sites of minerals from which lead was extracted. - Abstract: Bronze coins coming from the area of the Mediterranean basin, dated back the II–X Cent. A.D., were analyzed using different physical analytical techniques. Characteristic X-ray fluorescence was used with electrons and photons, in order to investigate the elemental composition of both the surface layers and bulk. Moreover, the quadrupole mass spectrometry coupled to laser ablation (LAMQS technique) in high vacuum was used to analyse typical material compounds from surface contamination. Mass spectrometry, at high resolution and sensitivity, extended up to 300 amu, allowed measuring the {sup 208}Pb/{sup 206}Pb and {sup 207}Pb/{sup 206}Pb isotopic ratios into the coins. Quantitative relative analyses of these isotopic ratios identify the coin composition such as a “fingerprint” depending on the mineral used to extract the lead. Isotopic ratios in coins can be compared to those of the possible minerals used to produce the bronze alloy. A comparison between the measured isotope ratios in the analyzed coins and the literature database, related to the mineral containing Pb as a function of its geological and geophysical extraction mine, is presented. The analysis, restricted to old coins and the mines of the Mediterranean basin, indicates a possible correlation between the coin compositions and the possible geological sites of the extracted mineral.

Investigation of laser cleaning on bronze cultural relics

International Nuclear Information System (INIS)

Ling, Xiulan; Wang, Gao; Zhang, Chen

2016-01-01

The effects of laser cleaning on the corrosion layers of bronze cultural relics were studied using a pulsed fiber laser. The laser cleaning threshold value of the corrosion layers was obtained. It was found that the corrosion layer was removed successfully by employing a laser fluence value of 0.32 J cm −2 and scanning for three times. To obtain experimental evidence, laser con-focal scanning microscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), laser induced breakdown spectroscopy (LIBS) and laser Raman spectroscopy were employed to investigate the cleaning efficiency of corrosion layers on specimens. (paper)

The covalent effect on the energy levels of d3 ions in tetragonal compounds

International Nuclear Information System (INIS)

Li, Dong-Yang; Du, Mao-Lu

2015-01-01

For d 3 ions in covalent compounds with tetragonal symmetry, this paper presents a complete energy matrix, in which the different covalence of t 2 and e orbitals is considered not only in the electrostatic repulsions part of energy matrix elements but also in the crystal-field potential part of energy matrix elements. With taking and no taking the crystal field parameter B 00 0 into account, the effect of covalence on the energy levels of d 3 ions system were investigated, respectively. The investigation shows that it is very necessary for considering the different covalence of t 2 and e orbitals in both electrostatic repulsions part and crystal-field potential part when the optical properties of d 3 ions in strong covalent compounds with tetragonal symmetry is investigated. On the other hand, the crystal field parameter B 00 0 has a significant effect on the energy levels, and should be considered in investigations of d 3 ions in strong covalent compounds with tetragonal symmetry. Application to calculating the energy levels for Co 2+ in CdGa 2 Se 4 , the calculated results are in agreement with the experiment data

Spall strength, dynamic elastic limit and fracture of ittrya dopped tetragonal zirconia

Science.gov (United States)

Milyavskiy, Vladimir; Savinykh, Andrey; Schlothauer, Thomas; Lukin, Evgeny; Akopov, Felix

2013-06-01

Specimens of the ceramics based on zirconia partially stabilized by yttrium oxide of the composition of 97 mol % ZrO2 + 3 mol % Y2O3 were prepared. The densities of the specimens were 5.79 and 6.01 g/cc. The ceramics mainly have the tetragonal structure (93-98 wt. % of t-ZrO2) . The mechanical action on the ceramic activates the transformation of the tetragonal phase into the monoclinic one: at the abrasive cutting or at the fracture by hammer shock, the content of the monoclinic phase is increasing. The same trend was observed in the specimens, recovered after stepwise shock compression up to 36, 52 and 99 GPa. It was found that shock compression do not initiates tetragonal-monoclinic phase transition directly, and this transition is caused by the destruction. Recovered specimens do not reveal any traces of the phase change which was observed by Mashimo et al. under the pressures 30-35 GPa (J. Appl. Phys. 1995. V. 77. P. 5069). Recording of the profiles of the free surface velocity of the specimens during single-stage shock compression allowed us to determine the dynamic elastic limit, as well as spall strength of the material versus maximal shock stress. In addition, the ceramics were subjected to the action of low temperatures. There were no significant changes in the specimens recovered after storage in liquid nitrogen and helium. The work was supported by The State Atomic Energy Corporation ROSATOM.

A New Chronology for the Bronze Age of Northeastern Thailand and Its Implications for Southeast Asian Prehistory.

Science.gov (United States)

Higham, Charles F W; Douka, Katerina; Higham, Thomas F G

2015-01-01

There are two models for the origins and timing of the Bronze Age in Southeast Asia. The first centres on the sites of Ban Chiang and Non Nok Tha in Northeast Thailand. It places the first evidence for bronze technology in about 2000 B.C., and identifies the origin by means of direct contact with specialists of the Seima Turbino metallurgical tradition of Central Eurasia. The second is based on the site of Ban Non Wat, 280 km southwest of Ban Chiang, where extensive radiocarbon dating places the transition into the Bronze Age in the 11th century B.C. with likely origins in a southward expansion of technological expertise rooted in the early states of the Yellow and Yangtze valleys, China. We have redated Ban Chiang and Non Nok Tha, as well as the sites of Ban Na Di and Ban Lum Khao, and here present 105 radiocarbon determinations that strongly support the latter model. The statistical analysis of the results using a Bayesian approach allows us to examine the data at a regional level, elucidate the timing of arrival of copper base technology in Southeast Asia and consider its social impact.

Specific corrosion product on interior surface of a bronze wine vessel with loop-handle and its growth mechanism, Shang Dynasty, China

Energy Technology Data Exchange (ETDEWEB)

Li Yang; Bao Zhirong; Wu Taotao [School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072 (China); Jiang, Junchun [Xiaogan Museum, Xiaogan 432000 (China); Chen Guantao [Center for Archaeometry, Wuhan University, Wuhan 430072 (China); Pan Chunxu, E-mail: cxpan@whu.edu.cn [School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072 (China); Center for Archaeometry, Wuhan University, Wuhan 430072 (China)

2012-06-15

In this paper, a kind of specific stalactitic product was found on the interior surface of a covered bronze wine vessel with loop-handle (Chinese name is you), which was fabricated in Shang Dynasty (1700 B.C.-1100 B.C.) and now is collected in Xiaogan Museum, Hubei province of China. The microstructures of the product were characterized systematically by using optical microscopy, scanning electron microscope, transmission electron microscope, X-ray diffraction, and Raman microscopy. The experimental results revealed that the product belonged to a kind of malachite with high purity and high crystallinity. The growth of the product was considered to be a possible reason that the vessel was overly airtight within a museum display cabinet besides a lid of the vessel, which made the excess of H{sub 2}O and CO{sub 2} gas concentrations inside the vessel during long-term storage. This corrosion product is very harmful to bronze cultural relics, because of a large amount of copper consumption from the matrix which will reduce its life. The growth mechanism of the specific stalactitic product and the suggestions for preservation of the similar bronze relics in museum were proposed. - Highlights: Black-Right-Pointing-Pointer The stalactitic product was the high purity and good crystallinity malachite. Black-Right-Pointing-Pointer Its growth was related to the excess of H{sub 2}O and CO{sub 2} gas concentrations in museum. Black-Right-Pointing-Pointer It is harmful to the bronzes, because copper will be consumed from the matrix. Black-Right-Pointing-Pointer The suggestions for preservation of the similar bronzes in museum were proposed.

Ferroelasticity of t'-zirconia. 1: High-voltage electron microscopy studies of the microstructure in polydomain tetragonal zirconia

International Nuclear Information System (INIS)

Baither, D.; Baufeld, B.; Messerschmidt, U.; Foitzik, A.H.; Ruehle, M.

1997-01-01

The microstructure of polydomain tetragonal zirconia (t'-ZrO 2 ), i.e., a ZrO 2 modification exhibiting ferroelastic behavior, is studied by high-voltage electron microscopy. This material consists of three domain variants of the tetragonal phase with their c-axes nearly orthogonal to each other. Always two variants of these platelike domains are alternately arranged, forming elongated regular colonies. Hence, in both variants the common habit plane of the domains is a {110} twin plane. The colonies are of columnar shape with a longitudinal axis. They are bound by {110} planes, too, which are twin planes for the domains in the contiguous colonies. Owing to their particular structure and the helical arrangement of the adjoining colonies, the material remains coherent and pseudocubic over large macroscopic regions, although it is formed by different tetragonal domains

Influence of the technology of melting and inoculation preliminary alloy AlBe5 on change of concentration of Al and micro-structure of the bronze CuAl10Ni5Fe4

Directory of Open Access Journals (Sweden)

B. Pisarek

2010-04-01

Full Text Available Examining was the aim of the work: influence of the permanent temperature 1300°C ± 15°C and changing time of isothermal holding in the range 0÷50 minutes on the melting loss of aluminum in the bronze CuAl10Ni5Fe4; the quantity the slag rafining - covering Unitop BA-1 (0÷1,5% on the effectiveness of the protection of liquid bronze before the oxygenation, the quantity of the preliminary alloy - in-oculant AlBe5 (0÷1,0% on the effective compensation melting loss of aluminum and time of isothermal holding on the effect of the in-oculation of the bronze and the comparison of the effectiveness of the inoculation of the bronze in furnace and in the form. Introduced investigations resulted from the study of the new grades of the Cu-Al-Fe-Ni bronze with additions singly or simultaneously Si, Cr, Mo and/or W, to melting which necessary it is for high temperature and comparatively long time isothermal holding indispensable to the occur of the process of diffusive dissolving the high-melting of the bronze components. High temperature and lengthening the time of isothermal holding the liquid bronze in casting furnace the melting loss of Al influences the growth. Addition the slag of covering-refining Unitop BA-1 in the quantity 1,5% the bronze protects before the melting loss of aluminum by the time of isothermal holding in the temperature 1300°C about 15 minutes. Addition of the preliminary alloy AlBe5 in the quantity 0,6% it assures the effective compensation of the aluminum which melting loss undergoes for the studied parameters of the melting. The effect of the inoculation of the bronze together with diminishes the preliminary alloy AlBe5 with lengthening the time of isothermal hold-ing. Because of this, use of the method of introducing the preliminary alloy it is seems good solution on the inoculation of aluminum bronzes directly to form, unsensitive on the time of isothermal holding the bronze.

Role of sintering time, crystalline phases and symmetry in the piezoelectric properties of lead-free KNN-modified ceramics

International Nuclear Information System (INIS)

Rubio-Marcos, F.; Marchet, P.; Merle-Mejean, T.; Fernandez, J.F.

2010-01-01

Lead-free KNN-modified piezoceramics of the system (Li,Na,K)(Nb,Ta,Sb)O 3 were prepared by conventional solid-state sintering. The X-ray diffraction patterns revealed a perovskite phase, together with some minor secondary phase, which was assigned to K 3 LiNb 6 O 17 , tetragonal tungsten-bronze (TTB). A structural evolution toward a pure tetragonal structure with the increasing sintering time was observed, associated with the decrease of TTB phase. A correlation between higher tetragonality and higher piezoelectric response was clearly evidenced. Contrary to the case of the LiTaO 3 modified KNN, very large abnormal grains with TTB structure were not detected. As a consequence, the simultaneous modification by tantalum and antimony seems to induce during sintering a different behaviour from the one of LiTaO 3 modified KNN.

Role of sintering time, crystalline phases and symmetry in the piezoelectric properties of lead-free KNN-modified ceramics

Energy Technology Data Exchange (ETDEWEB)

Rubio-Marcos, F., E-mail: frmarcos@icv.csic.es [Electroceramic Department, Instituto de Ceramica y Vidrio, CSIC, Kelsen 5, 28049 Madrid (Spain); Marchet, P.; Merle-Mejean, T. [SPCTS, UMR 6638 CNRS, Universite de Limoges, 123, Av. A. Thomas, 87060 Limoges (France); Fernandez, J.F. [Electroceramic Department, Instituto de Ceramica y Vidrio, CSIC, Kelsen 5, 28049 Madrid (Spain)

2010-09-01

Lead-free KNN-modified piezoceramics of the system (Li,Na,K)(Nb,Ta,Sb)O{sub 3} were prepared by conventional solid-state sintering. The X-ray diffraction patterns revealed a perovskite phase, together with some minor secondary phase, which was assigned to K{sub 3}LiNb{sub 6}O{sub 17}, tetragonal tungsten-bronze (TTB). A structural evolution toward a pure tetragonal structure with the increasing sintering time was observed, associated with the decrease of TTB phase. A correlation between higher tetragonality and higher piezoelectric response was clearly evidenced. Contrary to the case of the LiTaO{sub 3} modified KNN, very large abnormal grains with TTB structure were not detected. As a consequence, the simultaneous modification by tantalum and antimony seems to induce during sintering a different behaviour from the one of LiTaO{sub 3} modified KNN.

Alloy characterization of a 7th Century BC archeological bronze vase — Overcoming patina constraints using Monte Carlo simulations

Energy Technology Data Exchange (ETDEWEB)

Manso, M. [Laboratório de Instrumentação, Engenharia Biomédica e Fisica da Radiação (LIBPhys-UNL), Departamento de Fisica, Faculdade de Ciências e Tecnologias, Universidade Nova de Lisboa, 2829-516 Monte da Caparica (Portugal); Faculdade de Belas-Artes da Universidade de Lisboa, Largo da Academia Nacional de Belas-Artes, 1249-058 Lisboa (Portugal); Schiavon, N. [Hercules Laboratory, University of Évora, Palácio do Vimioso,Largo Marquês de Marialva 8, 7000-809 Évora Portugal (Portugal); Queralt, I. [Laboratory of X-ray Analytical Applications, Institute of Earth Sciences Jaume Almera, CSIC, Solé Sabaris s/n, 08028 Barcelona (Spain); Arruda, A.M. [Centro de Arqueologia da Universidade de Lisboa (UNIARQ), Alameda da Universidade, 1600-214 Lisboa (Portugal); Sampaio, J.M. [BioISI — Biosystems & Integrative Sciences Institute, Faculdade de Ciências da Universidade de Lisboa (Portugal); Brunetti, A., E-mail: brunetti@uniss.it [Department of Political Science and Communication, University of Sassari, Via Piandanna 2, 07100 Sassari (Italy)

2015-05-01

In this work we evaluate the composition of a bronze alloy using X-ray fluorescence spectrometry (XRF) and Monte Carlo (MC) simulations. For this purpose, a 7th Century BC archeological vase from the SW Iberian Peninsula, displaying a well formed corrosion patina was analyzed by means of a portable X-ray fluorescence spectrometer. Realistic MC simulations of the experimental setup were performed with the XRMC code package which is based on an intensive use of variance-reduction techniques and uses XRAYLIB a constantly updated X-ray library of atomic data. A single layer model was applied for simulating XRF of polished/pristine bronze whereas a two-or-three-layer model was developed for bronze covered respectively by a corrosion patina alone or coupled with a superficial soil derived crust. These simulations took into account corrosion (cerussite (PbCO{sub 3}), cuprite (Cu{sub 2}O), malachite (Cu{sub 2}CO{sub 3}(OH){sub 2}), litharge (PbO)) and soil derived products (goethite (FeO(OH)) and quartz (SiO{sub 2})) identified by means of X-ray diffraction and Raman micro analytical techniques. Results confirm previous research indicating that the XRF/Monte Carlo protocol is well suited when a two-layered model is considered, whereas in areas where the patina + soil derived products' crust is too thick, X-rays from the alloy substrate are not able to exit the sample. Quantitative results based on MC simulations indicate that the vase is made of a lead–bronze alloy: Mn (0.2%), Fe (1.0%), Cu (81.8%), As (0.5%), Ag (0.6%), Sn (8.0%) and Pb (8.0%). - Highlights: • We study an archeological bronze vase with patina corrosion using XRF spectrometry. • The experimental setup is modeled using Monte Carlo (MC) simulations. • Combining MC simulations with XRF it is possible to derive concentrations. • We demonstrated that this is possible without removing the patina.

Multielement analysis of archaic Chinese bronze and antique coins by fast neutron activation analysis

Energy Technology Data Exchange (ETDEWEB)

Tian, Y.H. (Academia Sinica, Lanzhou, Gansu (China). Inst. of Modern Physics); Pepelnik, R.; Fanger, H.U. (GKSS-Forschungszentrum Geesthacht GmbH, Geesthacht-Tesperhude (Germany, F.R.). Inst. fuer Physik)

1990-01-01

Samples of archaic bronze have been investigated by fast neutron activation analysis using both the absolute and relative method. The components Cu, Zn, Sn and Pb have been determined quantitatively. For the detection of lead via the short-lived isomeric state {sup 207m}Pb, cyclic activation and measurement technique was used with pneumatic sample transfer between detector and central irradiation position of the neutron tube. For non-destructive analysis of antique Chinese coins the samples had to be irradiated outside the neutron generator KORONA. The activation reactions, the evaluation of the elemental concentrations and the accuracy of the results are discussed. The data were corrected for {gamma}-ray self-absorption in the samples and summing of coincident {gamma}-rays in the detector. According to reported typical compositions of Chinese bronze from different dynasties, the age of the samples has been derived from the results obtained. (orig.).

Development of Cu-Be bronzes through powder metallurgy

International Nuclear Information System (INIS)

Abbas, M.

2012-01-01

Copper and copper alloys are the major group of commercial alloy. One of the important copper bronzes is Copper beryllium. This is unique among all engineering alloys. Copper beryllium alloy possesses the highest strength in all the copper base alloys. Development of copper beryllium alloy with powder metallurgy is challenging problem due to toxicity of beryllium dust. Purpose of this project to find out parameters by which copper beryllium with all unique properties should obtained. For this purpose efforts are put on development of alternative to copper beryllium system like copper-tin and copper-aluminum by powder metallurgy route. Different time of milling with uniaxial pressure of about 200 MPa and different sintering temperature according to phase diagram of alloy, with different soaking time is tried. Problems may occur like decrease in density after sintering, breaking of samples by Rockwell A, B and C indenters arid by hammering. Cold iso-static pressing at 300 MPa and sintering at above 900 degree C is used to develop copper beryllium alloy. As quenched samples are heat treated at 260 degree C, 315 degree C and 370 degree C with different soaking time of 30, 90 and 180 minutes to find out optimum time and temperature parameters. . It is observed that at aging at 260 degree C for 180 minutes, aging at 315 degree C for 180 minutes and aging at 370 degree C for 30 minutes produce optimum result. By observing these pellets by SEM, precipitates appeared in peak-aged alloy and bigger precipitates in over-aged alloy. Copper beryllium alloy developed through powder metallurgy has better prospects than other copper bronzes. (author)

Analysis of the Causes of Cracks in a Thick-Walled Bush Made of Die-Cast Aluminum Bronze

Directory of Open Access Journals (Sweden)

Pisarek B.P.

2016-12-01

Full Text Available For the die casting conditions of aluminium bronzes assumed based on the literature data, a thick-walled bush was cast, made of complex aluminium bronze (Cu-Al-Fe-Ni-Cr. After the cast was removed from the mould, cracks were observed inside it. In order to identify the stage in the technological production process at which, potentially, the formation of stresses damaging the continuity of the microstructure created in the cast was possible (hot cracking and/or cold cracking, a computer simulation was performed. The article presents the results of the computer simulation of the process of casting the material into the gravity die as well as solidifying and cooling of the cast in the shape of a thick-walled bush. The simulation was performed with the use of the MAGMA5 program and by application of the CuAl10Ni5,5Fe4,5 alloy from the MAGMA5 program database. The results were compared with the location of the defects identified in the actual cast. As a result of the simulation of the die-casting process of this bush, potential regions were identified where significant principal stresses accumulate, which can cause local hot and cold cracking. Until now, no research has been made of die-cast aluminium bronzes with a Cr addition. Correlating the results of the computer simulation validated by the analysis of the actual cast made it possible to clearly determine the critical regions in the cast exposed to cracking and point to the causes of its occurrence. Proposals of changes in the bush die casting process were elaborated, in order to avoid hot tearing and cold cracking. The article discusses the results of preliminary tests being a prologue to the optimization of the die-casting process parameters of complex aluminium bronze thick-walled bushs.

Bronze analysis by k0-NAA and PIXE

International Nuclear Information System (INIS)

Arana, G.; Waetjen, U.; Ingelbrecht, C.; Robouch, P.

2003-01-01

Five copper alloys were prepared with modern powder metallurgical processes in the frame of the European project 'Improvement of Means of Measurement on Archaeological Copper-Alloys for Characterisation and Conservation (IMMACO)' and certified for As, Pb, Sn and Zn mass fractions. Similar in their composition to archaeological bronze alloys, these Certified Reference Materials (CRMs) are to be used for calibration of XRF instruments for characterization of archaeological samples either in the laboratory or in the field. Successful contribution of non-destructive analytical methods (k 0 -NAA and PIXE) to the IMMACO project and to the certification of the five reference materials is presented. (author)

Nanosize stabilization of cubic and tetragonal phases in reactive plasma synthesized zirconia powders

Energy Technology Data Exchange (ETDEWEB)

Jayakumar, S., E-mail: sjayakumar.physics@gmail.com [Research and Development Centre, Bharathiar University, Coimbatore 641 014 (India); Department of Physics, Pollachi Institute of Engineering and Technology, Pollachi 642 205 (India); Ananthapadmanabhan, P.V.; Thiyagarajan, T.K. [Laser and Plasma Technology Division, BARC, Trombay, Mumbai 400 085 (India); Perumal, K. [Vision for Wisdom, Temple of Consciousness, Aliyar 642 101 (India); Mishra, S.C. [Department of Metallurgical and Materials Engg, National Institute of Technology, Rourkela 769 008 (India); Suresh, G. [Department of Physics, Park College of Engineering and Technology, Coimbatore 641 659 (India); Su, L.T.; Tok, A.I.Y. [School of Materials Science and Engg, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639 798 (Singapore)

2013-06-15

Pure zirconium oxide powders with particle size 2–33 nm are synthesized by reactive plasma processing. Transmission electron microscopy investigation of these particles revealed size dependent behavior for their phase stabilization. The monoclinic phase is found to be stable when particle size is ≥20 nm; Tetragonal is found to be stabilized in the range of 7–20 nm and as the particle size decreases to 6 nm and less, the cubic phase is stabilized. - Highlights: ► Direct conversion of micron-sized zirconium hydride powder to single crystal ZrO{sub 2} nanopowder. ► Size dependent stabilization of cubic, tetragonal and monoclinic phases in the reactive plasma synthesized ZrO{sub 2} nanopowder. ► Transmission electron microscopic investigation to identify particles of different sizes and their corresponding phase structure.

Martensitic cubic → tetragonal transition

International Nuclear Information System (INIS)

Schumann, H.

1983-01-01

Indium-thallium alloys containing 14 to 30% At. Tl have a cubic face-centred beta phase wich changes into a tetragonal face-centred alpha martensite during solidification. The martensite contains twin crystals that are large enough to be seen by means of a light microscope. The phenomenological crystallographic martensite theory was used to calculate Miller's index of the habit plane, the formation of the surface relief, the orientation relations and the critical thickness ratio of the twins. In a beta monocrystal frequently only one of the 24 crystallographic possible habit planes are formed at one end of the sample and migrate through the whole crystal when the temperature drops. Externally applied tension and compression influence in different ways the direction in which the habit plane moves and can even destroy the twinned structure, i.e. they can modify the substructure of the martensite crystal. This induces superelasticity, an effect that has also been described quantitatively. (author)

Metallurgical and mechanical examinations of steel–copper joints arc welded using bronze and nickel-base superalloy filler materials

International Nuclear Information System (INIS)

Velu, M.; Bhat, Sunil

2013-01-01

Highlights: ► Optical and scanning electron microscopy show defect free weld interfaces. ► Energy dispersive spectroscopy shows low dilution level of the weld by Fe. ► XRD studies show no brittle intermetallic phases in the weld interfaces. ► Weld interfaces did not fail during tensile, transverse bending and impact tests. ► The joint exhibits superior strength properties than that of bronze filler. - Abstract: The paper presents metallurgical and mechanical examinations of joints between dissimilar metals viz. copper (UNSC11000) and alloy steel (En31) obtained by Shielded Metal Arc Welding (SMAW) using two different filler materials, bronze and nickel-base super alloy. The weld bead of the joint with bronze-filler displayed porosity, while that with nickel-filler did not. In tension tests, the weldments with bronze-filler fractured in the centre of the weld, while those with nickel-filler fractured in the heat affected zone (HAZ) of copper. Since the latter exhibited higher strength than the former, all the major tests were undertaken over the joints with nickel-filler alone. Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) indicated corrugated weld interfaces and favorable elemental diffusions across them. X-ray diffraction (XRD) studies around the weld interfaces did not reveal any detrimental intermetallic compounds. Transverse bending tests showed that flexural strengths of the weldments were higher than the tensile strengths. Transverse side bend tests confirmed good ductility of the joints. Shear strength of the weld-interface (Cu–Ni or Ni–steel) was higher than the yield strength of weaker metal. Microhardness and Charpy impact values were measured at all the important zones across the weldment

Interspecific variation in resistance of Asian, European, and North American birches (Betula spp.) to bronze birch borer (Coleoptera: Buprestidae).

Science.gov (United States)

Nielsen, David G; Muilenburg, Vanessa L; Herms, Daniel A

2011-06-01

Bronze birch borer (Agrilus anxius Gory) is the key pest of birches (Betula spp.) in North America, several of which have been recommended for ornamental landscapes based on anecdotal reports of borer resistance that had not been confirmed experimentally. In a 20-yr common garden experiment initiated in 1979 in Ohio, North American birch species, including paper birch (Betula papyrifera Marshall), 'Whitespire' gray birch (Betula populifolia Marshall), and river birch (Betula nigra L.), were much more resistant to bronze birch borer than species indigenous to Europe and Asia, including European white birch (Betula pendula Roth), downy birch (Betula pubescens Ehrh.), monarch birch (Betula maximowicziana Regel), and Szechuan white birch (Betula szechuanica Jansson). Within 8 yr of planting, every European white, downy, and Szechuan birch had been colonized and killed, although 100% of monarch birch had been colonized and 88% of these plants were killed after nine years. Conversely, 97% of river birch, 76% of paper birch, and 73% Whitespire gray birch were alive 20 yr after planting, and river birch showed no evidence of colonization. This pattern is consistent with biogeographic theory of plant defense: North American birch species that share a coevolutionary history with bronze birch borer were much more resistant than naïve hosts endemic to Europe and Asia, possibly by virtue of evolution of targeted defenses. This information suggests that if bronze birch borer were introduced to Europe or Asia, it could threaten its hosts there on a continental scale. This study also exposed limitations of anecdotal observation as evidence of host plant resistance.

Stress-induced martensitic transformation and ferroelastic deformation adjacent microhardness indents in tetragonal zirconia single crystals

International Nuclear Information System (INIS)

Chien, F.R.; Ubic, F.J.; Prakash, V.; Heuer, A.H.

1998-01-01

The stress-induced tetragonal to monoclinic (t → m) martensitic transformation, stress-induced ferroelastic domain switching, and dislocation slip were induced by Vickers microindentation at elevated temperatures in polydomain single crystals of 3 mol%-Y 2 O 3 -stabilized tetragonal ZrO 2 single crystals (3Y-TZS). Chemical etching revealed traces along t directions adjacent to indentations, and Raman spectroscopy and TEM have shown that these traces are caused by products of the martensitic transformation, i.e. the monoclinic product phase forms primarily as thin, long plates with a habit plane approximately on (bar 301) m . This habit plane and the associated shear strain arising from the transformation, visible in TEM micrographs at the intersection of crystallographically equivalent martensite plates, were successfully predicted using the observed lattice correspondence and the phenomenological invariant plane strain theory of martensitic transformations. The extent of the martensitic transformation increased with increasing temperature from room temperature up to 300 C, but then decreased at higher temperatures. Ferroelastic deformation of tetragonal ZrO 2 has been observed at all temperatures up to 1,000 C. At the highest temperature, only ferroelastic domain switching and dislocation slip occurred during indentation-induced deformation

/sup 87/Rb NMR study at the cubic to tetragonal phase transition in RbCaF/sub 3/

Energy Technology Data Exchange (ETDEWEB)

Bulou, A [Angers Univ., 72 - Le Mans (France). Centre Universitaire; Theveneau, H; Trokiner, A; Papon, P [Ecole Superieure de Physique et Chimie Industrielles, 75 - Paris (France)

1979-07-01

The /sup 87/Rb nuclear magnetic resonance spectrum, in perovskite single crystal of RbCaF/sub 3/, is studied above and below the cubic-to-tetragonal phase transition occurring at 198 K. In the high-temperature cubic phase, the temperature dependence of the resonance line amplitude deviates from the Curie law and this can be attributed to the existence of tetragonal domains. In the low temperature tetragonal phase, a second-order quadrupole shift of the central line is observed, from which the CaF/sub 6/ tilt angle (order parameter) is derived. The order parameter temperature dependence is described by a power law with a cross over from exponent 0.5 to exponent 0.32 at 150 K. The tilt angle PHI is compared to the values obtained from X-ray and neutron powder diffraction data.

Improved multifilamentary Nb3Sn conductors produced by the titanium-bronze process

International Nuclear Information System (INIS)

Tachikawa, K.; Itoh, K.; Kamata, K.; Moriai, H.; Tada, N.

1985-01-01

The effects of a titanium addition to the bronze matrix of superconducting Nb 3 Sn wires have been investigated. The titanium addition to the matrix remarkably increases the Nb 3 Sn growth rate and the high-field, critical current density of the wire. An overall critical-current density of 3.8 . 10 4 A/cm 2 at 15 T has been obtained for the multifilamentary Nb/Cu-7.5 at.% Sn-0.4 at.% Ti wire with 4.7 μm-diameter 31 x 331 cores. The anisotropy in the critical current with respect to the field direction becomes larger with increasing aspect ratio of the rectangular-shaped multifilamentary wires. A 9.5 mm wide and 1.8mm thick Nb/Cu-7.5Sn-0.4Ti conductor with 5 μm-diameter 349 x 361=125 989 cores has been successfully fabricated on an industrial scale. This conductor carries a superconducting current of over 1300 A at 16.5 T. The newly developed Ti-bronze Nb 3 Sn conductor makes it feasible to generate a field of proportional 15 T in a large diameter bore. (orig.)

Generation of nanoparticles of bronze and brass by laser ablation in liquid

Energy Technology Data Exchange (ETDEWEB)

Sukhov, I.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Shafeev, G.A., E-mail: Shafeev@kapella.gpi.ru [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Voronov, V.V. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Sygletou, M. [Institute of Electronic Structure and Laser, Foundation for Research and Technology—Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece); Department of Physics, University of Crete, Vassilika Vouton, GR-711 10, Heraklion (Greece); Stratakis, E.; Fotakis, C. [Institute of Electronic Structure and Laser, Foundation for Research and Technology—Hellas (IESL-FORTH), P.O. Box 1527, Heraklion 711 10 (Greece)

2014-05-01

Nanoparticles of brass and bronze are generated by ablation of corresponding bulk targets in liquid ethanol. The experiments were performed using three pulsed lasers with different pulse duration: ytterbium fiber laser (80 ns), a Neodymium:YAG laser (10 ps), and femtosecond Ti:sapphire laser (200 fs). The generated nanoparticles (NPs) are characterized by UV–vis absorption spectroscopy, X-ray diffractometry, Raman scattering, and Transmission Electron Microscopy. The size of generated NPs lies in the range 10–25 nm depending on the laser source. The X-ray diffractometry reveals the change of phase composition of brass NPs compared to the initial target in case of ablation with 80 ns laser source, while with 10 ps laser pulses this effect is less pronounced. Brass NPs generated with pico- and femtosecond laser radiation show the plasmon resonance in the vicinity of 560 nm and no plasmon peak for NPs generated with longer laser pulses. Raman analysis shows the presence of Cu{sub 2}O in generated NPs. The stability of generated NPs of both brass and bronze to oxidation is compared to that of Cu NPs generated in similar experimental conditions.

Surface Analysis of Railway Buffers Heads Covered with Bronze Using Laser Cladding

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Sitarz M.

2017-06-01

Full Text Available Railway buffers during the operation are staying in almost permanent contact with each other, creating friction node in the point of contact of two railway buffer heads. In consequence of overcoming track curves, turnouts and unevenness of track, the railway buffer heads moves relative to each other causing friction, which results in its wear. When the wear is excessive, it might be a reason to withdrawn vehicle from service, it causes flattening of buffer head, and in consequence its abnormal cooperation. To avoid this phenomenon the buffer heads should be covered with graphitized grease, but this method has many disadvantages. Accordingly, it was found that it would be beneficial to cover the buffer head with bronze using laser cladding. In this article the metallographic and mechanical analysis of the newly created top layer of railway buffer head are presented. In article the results from tribological tests conducted on Amsler test bench are also presented. Based on test results described in article concluded that the layer of bronze coat on working surface of railway buffer head can be beneficial from operational point of view.

Horse-mounted invaders from the Russo-Kazakh steppe or agricultural colonists from western Central Asia? A craniometric investigation of the Bronze Age settlement of Xinjiang.

Science.gov (United States)

Hemphill, Brian E; Mallory, J P

2004-07-01

Numerous Bronze Age cemeteries in the oases surrounding the Täklamakan Desert of the Tarim Basin in the Xinjiang Uyghur Autonomous Region, western China, have yielded both mummified and skeletal human remains. A dearth of local antecedents, coupled with woolen textiles and the apparent Western physical appearance of the population, raised questions as to where these people came from. Two hypotheses have been offered by archaeologists to account for the origins of Bronze Age populations of the Tarim Basin. These are the "steppe hypothesis" and the "Bactrian oasis hypothesis." Eight craniometric variables from 25 Aeneolithic and Bronze Age samples, comprising 1,353 adults from the Tarim Basin, the Russo-Kazakh steppe, southern China, Central Asia, Iran, and the Indus Valley, are compared to test which, if either, of these hypotheses are supported by the pattern of phenetic affinities possessed by Bronze Age inhabitants of the Tarim Basin. Craniometric differences between samples are compared with Mahalanobis generalized distance (d2), and patterns of phenetic affinity are assessed with two types of cluster analysis (the weighted pair average linkage method and the neighbor-joining method), multidimensional scaling, and principal coordinates analysis. Results obtained by this analysis provide little support for either the steppe hypothesis or the Bactrian oasis hypothesis. Rather, the pattern of phenetic affinities manifested by Bronze Age inhabitants of the Tarim Basin suggests the presence of a population of unknown origin within the Tarim Basin during the early Bronze Age. After 1200 B.C., this population experienced significant gene flow from highland populations of the Pamirs and Ferghana Valley. These highland populations may include those who later became known as the Saka and who may have served as "middlemen" facilitating contacts between East (Tarim Basin, China) and West (Bactria, Uzbekistan) along what later became known as the Great Silk Road. Copyright

Tetragonal CuO: End member of the 3d transition metal monoxides

NARCIS (Netherlands)

Siemons, W.; Koster, Gertjan; Blank, David H.A.; Hammond, Robert H.; Geballe, Theodore H.; Beasley, Malcolm R.

2009-01-01

Monoclinic CuO is anomalous both structurally as well as electronically in the 3d transition metal oxide series. All the others have the cubic rocksalt structure. Here we report the synthesis and electronic property determination of a tetragonal (elongated rocksalt) form of CuO created using an

Strangers in a strange land: Egyptians in southern Palestine during the Bronze Age

Directory of Open Access Journals (Sweden)

Rachael Sparks

2002-10-01

Full Text Available When the Institute of Archaeology was formally established in 1937, it became responsible for housing Sir Flinders Petrie’s collection of archaeological material from Palestine. This unique inheritance has great value as a research collection, as its curator demonstrates here in her discussion of interaction between Egypt and Palestine in the Bronze Age.

Palaeodemographic and palaeopathological characteristics of individuals buried in three Bronze Age sites from southern Croatia

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M. Novak

2011-12-01

Full Text Available The purpose of this study is to reconstruct paleodemographic and paleopathological characteristics of sixteen individuals (three subadults, seven males and six females buried in three Bronze Age sites (Crip, Matkovići, and Veliki Vanik located in southern Croatia. The analysed sample is characterised by the presence of pathological changes which are often associated with stressful episodes such as anaemia, inadequate nutrition, infectious diseases and the occurrence of parasites. Cribra orbitalia, dental enamel hypoplasia, porotic hyperostosis and periostitis were observed in seven out of sixteen analysed skeletons. One ulnar “parry” fracture and three fractures of the frontal bone strongly suggest the presence of deliberate interpersonal violence within the studied communities. The average life span of the adults, as well as the number and character of the observed pathologies, suggest a relatively poor life quality and harsh living conditions in the studied region during the Bronze Age.

Effect of Annealing Time for Quenching CuAl7Fe5Ni5W2Si2 Bronze on the Microstructure and Mechanical Properties

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B. P. Pisarek

2012-04-01

Full Text Available This paper presents the influence of annealing time 30, 60 and 120 min at 1000°C for quenching CuAl7Fe5Ni5W2Si2 bronze in 10% water solution of NaCl, on the microstructure and mechanical properties. The presented results concern the species newly developed aluminum-iron-nickel bronze, with additions W and Si.In order to determine changes in the microstructure of the hardened bronze metallographic studies were performed on cylindrical samples of diameter 10 mm, on the metallographic microscope with digital image analysis, X-ray phase analysis, EDX point with the digital recording on the computer. Specified percentage of the microstructure of martensite and bainite, participation of proeutectoid α phase in the microstructure, grain size of former β phase, the amount of dissolved κ phase.It was found that in the microstructure of bronze in the cast state, there are a number of intermetallic phases of κ type. At interphase boundaries of primary intermetallic faceted precipitates, especially rich in tungsten (IM_W, nucleate and grow dendritic primary intermetallic κI phases, with chemical composition similar to the type of Fe3Si iron silicide.Dissolved, during the heating, in the β phase are all the intermediate phase included in the microstructure, with the exception of primary intermetallic phases of tungsten and κI. Prolongation of the isothermal annealing causes coagulation and coalescence of primary phases. In microstructure of the bronze after quenching obtained the α phase precipitation on the grain boundary of secondary β phase, coarse bainite and martensite, for all annealing times. With the change of annealing time are changed the relative proportions of individual phases or their systems, in the microstructure. In the microstructure of bronze, hold at temperature of 1000°C for 60 min, after quenching martensitic microstructure was obtained with the primary phases, and the least amount of bainite.

Abnormal photothermal effect of laser radiation on highly defect oxide bronze nanoparticles under the sub-threshold excitation of absorption

Science.gov (United States)

Gulyaev, P.; Kotvanova, M.; Omelchenko, A.

2017-05-01

The mechanism of abnormal photo-thermal effect of laser radiation on nanoparticles of oxide bronzes has been proposed in this paper. The basic features of the observed effect are: a) sub-threshold absorption of laser radiation by the excitation of donor-like levels formed in the energy gap due to superficial defects of the oxide bronze nano-crystals; b) an interband radiationless transition of energy of excitation on deep triplet levels and c) consequent recombination occurring at the plasmon absorption. K or Na atoms thermally intercalated to the octahedral crystal structure of TiO2 in the wave SHS combustion generate acceptor levels in the gap. The prepared oxide bronzes of the non-stoichiometric composition NaxTiO2 and KxTiO2 were examined by high resolution TEM, and then grinded in a planetary mill with powerful dispersion energy density up to 4000 J/g. This made it possible to obtain nanoparticles about 50 nm with high surface defect density (1017-1019 cm-2 at a depth of 10 nm). High photo-thermal effect of laser radiation on the defect nanocrystals observed after its impregnation into cartilaginous tissue exceeds 7 times in comparison with the intact ones.

Stress Analysis and Fatigue Behaviour of PTFE-Bronze Layered Journal Bearing under Real-Time Dynamic Loading

Science.gov (United States)

Duman, M. S.; Kaplan, E.; Cuvalcı, O.

2018-01-01

The present paper is based on experimental studies and numerical simulations on the surface fatigue failure of the PTFE-bronze layered journal bearings under real-time loading. ‘Permaglide Plain Bearings P10’ type journal bearings were experimentally tested under different real time dynamic loadings by using real time journal bearing test system in our laboratory. The journal bearing consists of a PTFE-bronze layer approximately 0.32 mm thick on the steel support layer with 2.18 mm thick. Two different approaches have been considered with in experiments: (i) under real- time constant loading with varying bearing widths, (ii) under different real-time loadings at constant bearing widths. Fatigue regions, micro-crack dispersion and stress distributions occurred at the journal bearing were experimentally and theoretically investigated. The relation between fatigue region and pressure distributions were investigated by determining the circumferential pressure distribution under real-time dynamic loadings for the position of every 10° crank angles. In the theoretical part; stress and deformation distributions at the surface of the journal bearing analysed by using finite element methods to determine the relationship between stress and fatigue behaviour. As a result of this study, the maximum oil pressure and fatigue cracks were observed in the most heavily loaded regions of the bearing surface. Experimental results show that PTFE-Bronze layered journal bearings fatigue behaviour is better than the bearings include white metal alloy.

Nordic and Celtic: religion in southern Scandinavia during the late bronze age and early iron age

Directory of Open Access Journals (Sweden)

Marianne Görman

1990-01-01

Full Text Available By means of modern archeological research it is today possible to gain much information even from non-written material, This paper covers the late bronze age and early iron age, ca. 1000 B.C. —O. It is based on material from Denmark, the Southwest of Sweden, and the Southeast of Norway. This region formed a cultural unity since the sea bound the area together. Our main sources of knowledge of Nordic religion during this time span are votive offerings and rock-carvings. During the bronze age and early iron age the Nordic peasant population had intensive contacts with the Southeastern and Centralparts of Europe. A great quantity of imported objects bear evidence of widespread connections. The inhabitants of the Nordic area not only brought home objects, but also ideas and religious conceptions. This is clearly reflected in the iconography. The cultures with which connections were upheld and from which ideas were introduced were those of Hallstatt and La Tène. They were both Celtic iron age cultures prospering in Central Europe at the same time as the late bronze age and early iron age in the Nordic area. This means that the new symbols in the Nordic area come from a Celtic environment. Consequently, Celtic religion such as it may be found in the pre-Roman period, can clarify the meaning of the conceptions, linked with these symbols.

Prevention of Dealloying in Manganese Aluminium Bronze Propeller: Part II

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Napachat Tareelap

2014-03-01

Full Text Available Due to the failure of manganese aluminium bronze (MAB propeller caused by dealloying corrosion as described in Part I [1], this work aims to study the prevention of dealloying corrosion using aluminium and zinc sacrificial anodes. The results indicated that both of the sacrificial anodes could prevent the propeller from dealloying. Moreover, the dealloying in seawater was less than that found in brackish water. It was possible that hydroxide ions, from cathodic reaction, reacted with calcium in seawater to form calcium carbonate film protecting the propeller from corrosion.

Atomistic studies of cation transport in tetragonal ZrO2 during zirconium corrosion

International Nuclear Information System (INIS)

Bai, Xian-Ming; Zhang, Yongfeng; Tonks, Michael R.

2015-01-01

Zirconium alloys are the major fuel cladding materials in current reactors. The water-side corrosion is a significant degradation mechanism of these alloys. During corrosion, the transport of oxidizing species in zirconium dioxide (ZrO 2 ) determines the corrosion kinetics. Previously, it has been argued that the outward diffusion of cations is important for forming protective oxides. In this work, the migration of Zr defects in tetragonal ZrO 2 is studied with temperature accelerated dynamics and molecular dynamics simulations. The results show that Zr interstitials have anisotropic diffusion and migrate preferentially along the [001] or c direction in tetragonal ZrO 2 . The compressive stresses can increase the Zr interstitial migration barrier significantly. The migration of Zr interstitials at a grain boundary is much slower than in a bulk oxide. The implications of these atomistic simulation results in the Zr corrosion are discussed. (authors)

Development of technology and properties investigation of steel/bronze joints proposed for ITER HHF components manufacturing

International Nuclear Information System (INIS)

Kalinin, G.; Krestnikov, N.S.; Strebkov, Y.S.; Abramov, V.Y.; Gervash, A.; Mazul, I.; Zolotarev, V.B.; Fabritsiev, S.A.

2007-01-01

Full text of publication follows: During the development of ITER HHF components manufacturing it is necessary to provide reliable joints between heat sink material made of CuCrZr bronze and the supporting construction made of austenitic steel. Four different methods have been tried out: - Hot Isostatic Pressing (HIP), - HIP assisted brazing, - furnace assisted brazing, - Casting. The investigation of structure and properties of joints show that HIP and casting provide the better results than the other technologies. However, HIP is relatively expensive technology, and big size HIP furnace is required for the full scale components manufacturing that are not available n RF now. Therefore, casting was selected as a reference manufacturing technology for the primary wall of ITER modules n RF. The paper summarizes the results of bronze/steel joints manufacturing and investigation of their properties. (authors)

Mobility in Central European Late Eneolithic and Early Bronze Age: femoral cross-sectional geometry

Czech Academy of Sciences Publication Activity Database

Sládek, Vladimír; Berner, M.; Sailer, R.

2006-01-01

Roč. 130, č. 3 (2006), s. 320-332 ISSN 0002-9483 R&D Projects: GA ČR GP206/01/D018 Institutional research plan: CEZ:AV0Z60930519 Keywords : biomechanics * mobility * bone strength * Late Eneolithic * Early Bronze Age Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 2.136, year: 2006

The Romanesque Bronze Doors at Gniezno Cathedral Church: Some New Remarks

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Tomasz Węcławowicz

2017-06-01

Full Text Available Among many Romanesque bronze doors in Europe the old entrance doors of the metropolitan cathedral in Gniezno, in the North Poland, are exceptional. For over a century many historians and historians of art have been trying to understand and explain its iconographic phenomenon. The Polish, Czech and German scholars have so far been unable to identify with any conviction, either the iconographic models or artistic provenance of the workshop. There were suggested some connections of the alleged bishop patrons to France and there were emphasizes technological possibilities of foundry workshops at the Meuse Valley. This “Meuse hypothesis” based mainly on historical suggestions became established as a certainty. However, it is important to emphasize the significant difference between the creator of the composition and of the craftsman who cast the bronze door. Years ago only Lech Kalinowski pointed out some general formal similarities to the North Italian sculpture. The purpose of this paper is to develop Kalinowski’s suggestions and to emphasise the puzzling similarities between details of Gniezno doors and some Emilian works executed by Master Wiligelmo da Modena and Master Nicolò. The concept of Italian relationship from Emilia province seems to be better for the comparative analysis than relationship with Meuse Valley based mostly on historical context. Crucial here is the additional, parallel analysis of the portal decoration in Czerwinsk Abbey.

On the Tetragonal Forms of KMo 4O 6

Science.gov (United States)

McCarroll, W. H.; Ramanujachary, K. V.; Greenblatt, M.; Marsh, Richard E.

1995-06-01

A reexamination of the X-ray diffraction data for the tetragonal form of KMo4O6 prepared by fused salt electrolysis leads to the conclusion that the crystal structure is better described by using space group P 4/mbm and not P4¯ as previously reported. However, refinement in the new space group does not result in any significant changes in the atomic arrangement. Possible reasons for the significant difference between the c lattice parameter of this form of KMo4O6 and that prepared at high pressures are also discussed.

Crystal structure of red lead titanate thin films

International Nuclear Information System (INIS)

Bursill, L.A.; Peng, J.L.; Jiang, B.; Li, X.

1998-01-01

Orange-red lead titanate thin films are examined by high-resolution transmission electron microscopy and diffraction. It is remarkable that the structure is based on that of tetragonal-tungsten-bronze (TTB) rather than perovskite-type. The chemical basis for this result is examined. It is deduced that the TTB structure is stabilized by inclusion of hydroxyl ions during synthesis by a sol-gel route involving hydrolysis of n-Butyl titanate

Dissolution of copper, tin, and iron from sintered tungsten-bronze spheres in a simulated avian gizzard, and an assessment of their potential toxicity to birds

International Nuclear Information System (INIS)

Thomas, Vernon G.; McGill, Ian R.

2008-01-01

The rates of dissolution of copper, tin, and iron from sintered tungsten-bronze spheres (51.1%W, 44.4%Cu, 3.9%Sn, 0.6%Fe, by mass) were measured in an in vitro simulated avian gizzard at pH 2.0, and 42C. Most of the spheres had disintegrated completely to a fine powder by day 14. Dissolution of copper, tin, and iron from the spheres was linear over time; all r > 0.974; all P < 0.001. The mean rate of release of copper, tin, and iron was 30.4 mg, 2.74 mg, and 0.38 mg per g tungsten-bronze per day, respectively. These rates of metal release were compared to those in published studies to determine whether the simultaneous ingestion of eight spheres of 3.48 mm diameter would pose a toxic risk to birds. The potential absorption rates of iron and tin (0.54 mg Fe/day, and 3.89 mg Sn/day) from eight tungsten-bronze spheres of total mass 1.42 g would not prove toxic, based on empirical studies of tin and iron ingestion in waterfowl. The release of 43.17 mg copper/day from eight tungsten-bronze spheres, while exceeding the daily copper requirements of domesticated birds, is far below the levels of copper known to cause copper toxicosis in birds. We conclude that sintered tungsten-bronze material made into gunshot, fishing weights, or wheel balance weights, would not pose a toxic risk to wild birds when ingested

Toughening of dental porcelain by tetragonal ZrO2 additions

International Nuclear Information System (INIS)

Morena, R.; Lockwood, P.E.; Evans, A.L.; Fairhurst, C.W.

1986-01-01

The effect of mechanical behavior of ZrO 2 additions to a dental porcelain was investigated. The ZrO 2 was introduced into the glassy matrix phase of the porcelain by refritting the all-glass porcelain constituent. X-ray diffraction indicated that a sizeable fraction of the ZrO 2 was retained in the tetragonal from after the porcelain was fired. Zirconia additions to the porcelain produced substantial improvements in fracture toughness, strength, and thermal shock resistance

Diet Reconstructed From an Analysis of Plant Microfossils in Human Dental Calculus From the Bronze Age Site of Shilinggang, Southwestern China

Science.gov (United States)

Zhang, N.; Dong, G.; Yang, X.; Zuo, X.; Kang, L.; Ren, L.; Liu, H.; Li, H.; Min, R.; Liu, X.; Zhang, D.; Chen, F.

2017-12-01

The extracted microfossils from the dental calculus of ancient teeth are a new form of archaeological evidence which can provide direct information on the plant diet of a population. Here, we present the results of analyses of starch grains and phytoliths trapped in the dental calculus of humans who occupied the Bronze Age site of Shilinggang ( 2500 cal yr BP) in Yunnan Province, southwestern China. The results demonstrate that the inhabitants consumed a wide range of plants, including rice, millet, and palms, together with other food plants which have not previously been detected in Yunnan. The discovery of various underground storage organs (USOs; tubers, roots, bulbs, and rhizomes) and acorns complements the application of conventional macrofossil and isotope studies to understand the diet of the Bronze Age human population of Yunnan. The wide variety of plant foods consumed suggests that the inhabitants adopted a broad-spectrum strategy of gathering food and cultivating crops in northwest Yunnan Province in the late Bronze Age at a time when agricultural societies were developed in the central plains of China.

Electronic band structure and charge density wave transition in quasi-2D KMo6O17 purple bronze

Science.gov (United States)

Valbuena, M. A.; Avila, J.; Vyalikh, D. V.; Guyot, H.; Laubschat, C.; Molodtsov, S. L.; Asensio, M. C.

2008-03-01

High resolution angle-resolved photoemission of quasi-2D KMo6O17 purple bronze has been performed in the range from room temperature to 130 K, slightly above the charge density wave (CDW) transition (Tc = 110 K), and down to 35 K (well below Tc). In this paper we report a detailed study of how electronic band structure is affected by this transition driven by the hidden nesting scenario. The expected spectroscopic fingerprints of the CDW phase transition have been found and discussed according to the hidden one dimension and the development of a quasi-commensurate CDW. The excellent agreement between theory and our experimental results makes of potassium purple bronze a reference system for studying this type of instabilities.

Electronic band structure and charge density wave transition in quasi-2D KMo6O17 purple bronze

International Nuclear Information System (INIS)

Valbuena, M A; Avila, J; Asensio, M C; Vyalikh, D V; Laubschat, C; Molodtsov, S L; Guyot, H

2008-01-01

High resolution angle-resolved photoemission of quasi-2D KMo 6 O 17 purple bronze has been performed in the range from room temperature to 130 K, slightly above the charge density wave (CDW) transition (T c = 110 K), and down to 35 K (well below T c ). In this paper we report a detailed study of how electronic band structure is affected by this transition driven by the hidden nesting scenario. The expected spectroscopic fingerprints of the CDW phase transition have been found and discussed according to the hidden one dimension and the development of a quasi-commensurate CDW. The excellent agreement between theory and our experimental results makes of potassium purple bronze a reference system for studying this type of instabilities

A Living Landscape : Bronze Age settlement sites in the Dutch river area (c. 2000-800 BC)

NARCIS (Netherlands)

Arnoldussen, Stijn

2008-01-01

"A Living Landscape. Bronze Age settlements in the Dutch river area (c. 2000-800 BC)" Academisch proefschrift over de aard en dynamiek van bronstijdnederzettingen in het rivierengebied. Het bevat een introductie op de geologische processen en de paleogeografie van de Nederlandse rivierdelta als

Exposition and Synthesis of Benin Bronze Casting: Emphasis on the Olotan Casters of Benin

Science.gov (United States)

Ifeta, Chris Funke

2016-01-01

The introduction of Western education to Nigeria has brought in its wake great strides toward development. Changes in Benin dates far back to the dawn of the 20th century. This paper investigates the critical role of education in development. The paper integrates interview data collected from bronze casters in Benin. The first section of the paper…

Yttria-Ceria stabilized tetragonal zirconia polycrystals: Sintering, grain growth and grain boundary segregation

NARCIS (Netherlands)

Boutz, M.M.R.; Boutz, M.M.R.; Winnubst, Aloysius J.A.; Burggraaf, Anthonie; Burggraaf, A.J.

1994-01-01

An analysis is presented of grain growth and densification of yttria-ceria stabilized tetragonal zirconia polycrystals (Y, Ce-TZPs) using both isothermal and non-isothermal techniques. The characteristics of Y, Ce-TZPs are compared to those of Y-TZP and Ce-TZP and the effect of increasing ceria

Roman Bronze Vessels From the Late Sarmatian Burial of the Lebedevka Burial-Ground in Western Kazakhstan

Directory of Open Access Journals (Sweden)

Treister Mikhail Yuryevich

2015-12-01

Full Text Available This paper is devoted to studying cultural monuments – bronze vessels, a jug and a basin from the barrow no. 1/1967 of the Lebedevka Late Sarmatian burial mound (Western Kazakhstan, dating back to the middle of the 3rd century AD at the latest. These items do not find exact parallels among the bronze vessels of provincial Rome. Although the shape of the jug handle with a curved leaf turned upright between two horizontally arranged swan heads has parallels on the so-called “composite jug with handles” (“gegliederten Henkelkrügen”, the cylindrical form of the jug’s neck peculiar of the glass jugs of allegedly Syrian manufacture of the second half of the 3rd-4th centuries AD is very unusual. Even more unusual is a basin with horizontally bent rim and elaborate handles with pearls on a high narrow stand-ring. The XRF analyses of the Lebedevka jug’s metal revealed that its body and handle were made of a copper-based alloy with very high admixtures of zinc (24-27 % and inconsiderable additions of lead (up to 3 %. A similar alloy was used for manufacturing a vessel in the form of a crouching young negro from Niederbieber. Most objects of provincial Roman import reached Western Kazakhstan via the Bosporan kingdom along the Northern branch of the Silk Road. The above discussed bronze vessels from Lebedevka let suggest, that the nomads could receive some import articles that were brought along the caravan routes leading from Egypt and Syria to the East.

Finite element analysis of the tetragonal to monoclinic phase transformation during oxidation of zirconium alloys

Energy Technology Data Exchange (ETDEWEB)

Platt, P., E-mail: Philip.Platt@manchester.ac.uk [University of Manchester, School of Materials, Materials Performance Centre, Manchester M13 9PL (United Kingdom); Frankel, P. [University of Manchester, School of Materials, Materials Performance Centre, Manchester M13 9PL (United Kingdom); Gass, M.; Howells, R. [AMEC, Walton House, Faraday Street, Birchwood Park, Risley, Warrington WA3 6GA (United Kingdom); Preuss, M. [University of Manchester, School of Materials, Materials Performance Centre, Manchester M13 9PL (United Kingdom)

2014-11-15

Corrosion is a key limiting factor in the degradation of zirconium alloys in light water reactors. Developing a mechanistic understanding of the corrosion process offers a route towards improving safety and efficiency as demand increases for higher burn-up of fuel. Oxides formed on zirconium alloys are composed of both monoclinic and meta-stable tetragonal phases, and are subject to a number of potential mechanical degradation mechanisms. The work presented investigates the link between the tetragonal to monoclinic oxide phase transformation and degradation of the protective character of the oxide layer. To achieve this, Abaqus finite element analysis of the oxide phase transformation has been carried out. Study of the change in transformation strain energy shows how relaxation of oxidation induced stress and fast fracture at the metal–oxide interface could destabilise the tetragonal phase. Central to this is the identification of the transformation variant most likely to form, and understanding why twinning of the transformed grain is likely to occur. Development of transformation strain tensors and analysis of the strain components allows some separation of dilatation and shear effects. Maximum principal stress is used as an indication of fracture in the surrounding oxide layer. Study of the stress distributions shows the way oxide fracture is likely to occur and the differing effects of dilatation and shape change. Comparison with literature provides qualitative validation of the finite element simulations.

Finite element analysis of the tetragonal to monoclinic phase transformation during oxidation of zirconium alloys

Science.gov (United States)

Platt, P.; Frankel, P.; Gass, M.; Howells, R.; Preuss, M.

2014-11-01

Corrosion is a key limiting factor in the degradation of zirconium alloys in light water reactors. Developing a mechanistic understanding of the corrosion process offers a route towards improving safety and efficiency as demand increases for higher burn-up of fuel. Oxides formed on zirconium alloys are composed of both monoclinic and meta-stable tetragonal phases, and are subject to a number of potential mechanical degradation mechanisms. The work presented investigates the link between the tetragonal to monoclinic oxide phase transformation and degradation of the protective character of the oxide layer. To achieve this, Abaqus finite element analysis of the oxide phase transformation has been carried out. Study of the change in transformation strain energy shows how relaxation of oxidation induced stress and fast fracture at the metal-oxide interface could destabilise the tetragonal phase. Central to this is the identification of the transformation variant most likely to form, and understanding why twinning of the transformed grain is likely to occur. Development of transformation strain tensors and analysis of the strain components allows some separation of dilatation and shear effects. Maximum principal stress is used as an indication of fracture in the surrounding oxide layer. Study of the stress distributions shows the way oxide fracture is likely to occur and the differing effects of dilatation and shape change. Comparison with literature provides qualitative validation of the finite element simulations.

Finite element analysis of the tetragonal to monoclinic phase transformation during oxidation of zirconium alloys

International Nuclear Information System (INIS)

Platt, P.; Frankel, P.; Gass, M.; Howells, R.; Preuss, M.

2014-01-01

Corrosion is a key limiting factor in the degradation of zirconium alloys in light water reactors. Developing a mechanistic understanding of the corrosion process offers a route towards improving safety and efficiency as demand increases for higher burn-up of fuel. Oxides formed on zirconium alloys are composed of both monoclinic and meta-stable tetragonal phases, and are subject to a number of potential mechanical degradation mechanisms. The work presented investigates the link between the tetragonal to monoclinic oxide phase transformation and degradation of the protective character of the oxide layer. To achieve this, Abaqus finite element analysis of the oxide phase transformation has been carried out. Study of the change in transformation strain energy shows how relaxation of oxidation induced stress and fast fracture at the metal–oxide interface could destabilise the tetragonal phase. Central to this is the identification of the transformation variant most likely to form, and understanding why twinning of the transformed grain is likely to occur. Development of transformation strain tensors and analysis of the strain components allows some separation of dilatation and shear effects. Maximum principal stress is used as an indication of fracture in the surrounding oxide layer. Study of the stress distributions shows the way oxide fracture is likely to occur and the differing effects of dilatation and shape change. Comparison with literature provides qualitative validation of the finite element simulations

Archaeometric study of a bronze age sword discovered at Giurgiu, Romania

International Nuclear Information System (INIS)

Olariu, Agata; Badica, Teodor; Alexandrescu, Emilian; Avram, Alexandru

2008-01-01

The compositional scheme of a Bronze Age sword, found near the town of Giurgiu in Romania has been determined by the method of particle-induced X-ray emission (PIXE). The elemental composition of the sword was compared with the composition of other swords from the same geographic area, the Danubian plain from Bulgaria, and Transylvania regions. Both the physical analyzes and the archaeological considerations show that the sword from Giurgiu could be associated with the swords from Bulgaria, having compositional, stylistic, temporal and geographical similitudes. (authors)

Ordering of Nb3Sn layer formed in the bronze process

International Nuclear Information System (INIS)

Agarwal, S.K.; Nagpal, K.C.; Narlikar, A.G.

1986-01-01

The work reported here suggests that the ordering of superconducting Nb 3 Sn compound layers formed in the bronze process is much more intriguing than previously assumed. Various possible mechanisms of ordering of the layers have been examined in conjunction with the observed data on short duration annealed samples. The analysis suggests the ordering to be governed by a sequential operation of both Ist and IInd order kinetics, and seems to fall in line with the studies on disordered bulk samples annealed for long durations. (author)

Analysis of selective laser cleaning of patina on bronze coins

International Nuclear Information System (INIS)

Buccolieri, G; Nassisi, V; Castellano, A; Di Giulio, M; Giuffreda, E; Delle Side, D; Velardi, L; Torrisi, L; Buccolieri, A

2014-01-01

The patina, is the result of a large number of chemical, electrochemical and physical processes which occur spontaneously during interaction of metal surfaces with the environment. In this work we want to analyze and remove the patina in artefacts, exposed to atmosphere for various decades. Here, experimental results about the laser cleaning of bronze coins by KrF (248 nm) and Nd:YAG (532 nm) lasers are reported. Both laser wavelengths were efficient to reduce the chlorine concentration on the surface of the coins more than 80 %, as demonstrated by Energy Dispersive X-Ray Fluorescence analyses.

Archaeointensity study of five Late Bronze Age fireplaces from Corent (Auvergne, France)

OpenAIRE

Hervé , Gwenaël; Chauvin , Annick; Milcent , Pierre-Yves; Tramon , Arthur

2016-01-01

International audience; Recent excavations at Corent (France) unearthed a vast Late Bronze Age settlement. The high density of fireplaces especially highlights it. The present study focuses on the archaeomagnetic study of five fireplaces. These ones were dated between 950 and 800 BCE by cross-dating of metallic and ceramic artefacts and by radiocarbon. The main objective of our study is to increase the archaeointensity database in Western Europe at the beginning of the first millennium BCE. T...

Spatially modulated magnetic structure of EuS due to the tetragonal domain structure of SrTiO3 APS

CERN Document Server

Rosenberg, Aaron J.; Kirtley, John R.; Gedik, Nuh; Moodera, Jagadeesh S.; Moler, Kathryn A.

2017-12-15

The combination of ferromagnets with topological superconductors or insulators allows for new phases of matter that support excitations such as chiral edge modes and Majorana fermions. EuS, a wide-bandgap ferromagnetic insulator with a Curie temperature around 16 K, and SrTiO3 (STO), an important substrate for engineering heterostructures, may support these phases. We present scanning superconducting quantum interference device measurements of EuS grown epitaxially on STO that reveal micron-scale variations in ferromagnetism and paramagnetism. These variations are oriented along the STO crystal axes and only change their configuration upon thermal cycling above the STO cubic-to-tetragonal structural transition temperature at 105 K, indicating that the observed magnetic features are due to coupling between EuS and the STO tetragonal structure. We speculate that the STO tetragonal distortions may strain the EuS, altering the magnetic anisotropy on a micron scale. This result demonstrates that local variation in...

Solar Orientations of Bronze Age Shrines in Gournia, Crete

Science.gov (United States)

Henriksson, G.; Blomberg, M.

2009-08-01

The measurements of orientations at Gournia are part of the Uppsala University project to investigate the nature of Minoan astronomy. The town is typical of Minoan settlements and therefore was chosen for the selection of representative buildings from different kinds of Minoan sites. We use classical archaeoastronomical methods and our own computer programs for calculation of the positions of the sun, moon and stars in the Aegean Bronze Age. We discovered that Gournia is the fourth Minoan site with shrines that are oriented to sunrise at lunar month intervals with respect to the equinoxes. There is also a Mycenaean shrine in the town and we compared its orientation to Mycenaean buildings of the same type in Crete.

Crystalline mesoporous zirconia catalysts having stable tetragonal pore wall structure

Science.gov (United States)

Sachtler, W.M.H.; Huang, Y.Y.

1998-07-28

Methods are disclosed for the preparation of new sulfated mesoporous zirconia materials/catalysts with crystalline pore walls of predominantly tetragonal crystal structure, characterized by nitrogen physical sorption measurement, X-ray diffraction, transmission electron microscopy and catalytic tests using n-butane isomerization to iso-butane and alkylation of 1-naphthol with 4-tert-butylstyrene as probe reactions. Sulfate deposition is preferred for the transformation of a mesoporous precursor with amorphous pore walls into a material with crystalline pore walls maintaining the mesoporous characteristics. 17 figs.

A Method to Make Classification of the Heat Treatment Processes Performed on Bronze Using Incomplete Knowledge

Directory of Open Access Journals (Sweden)

Kluska-Nawarecka S.

2014-06-01

Full Text Available The article describes the problem of selection of heat treatment parameters to obtain the required mechanical properties in heat- treated bronzes. A methodology for the construction of a classification model based on rough set theory is presented. A model of this type allows the construction of inference rules also in the case when our knowledge of the existing phenomena is incomplete, and this is situation commonly encountered when new materials enter the market. In the case of new test materials, such as the grade of bronze described in this article, we still lack full knowledge and the choice of heat treatment parameters is based on a fragmentary knowledge resulting from experimental studies. The measurement results can be useful in building of a model, this model, however, cannot be deterministic, but can only approximate the stochastic nature of phenomena. The use of rough set theory allows for efficient inference also in areas that are not yet fully explored.

$Nb_{3}Sn macrostructure, microstructure, and property comparisons for bronze and internal Sn process strands

CERN Document Server

Lee, P J; Larbalestier, D C

2000-01-01

The variation in irreversibility field, B*(T), with temperature has been measured for Nb/sub 3/Sn superconducting strands manufactured for ITER using vibrating sample and SQUID magnetometers. The high performance strands were developed for both high transport critical current density, J/sub c/, and low hysteresis loss. Despite a wide variety of designs and components, the strands could be split into two distinctive groups, based on the extrapolated irreversibility fields, which lie about 10% lower than the upper critical field. "Bronze-process" strands exhibited consistently higher B*(T) (28 T to 31 T) compared with "internal Sn" process (24 T to 26 T) conductors. The intrinsic critical current density of the superconductor, J/sub c (sc)/, and the specific pinning force of the grain boundaries, Q/sub gb/, were evaluated using the measured J/sub c/, and image analysis of the macro- and micro-structures. A bronze-processed Nb(-Ta)/sub 3 /Sn was found to have a higher J/sub c(sc)/ but lower Q/sub gb/ than Nb/sub...

Superconductivity in an anomalously tetragonal YB2C3O6.62 single crystal: A possible singularity in the structural phase diagram

DEFF Research Database (Denmark)

Frello, T.; Andersen, N.H.; Baziljevich, M.

2003-01-01

superconducting. This makes the sample highly anomalous in two respects: with a stoichiometry of YBa2Cu3O6.62 the sample should have an orthorhombic symmetry, and a tetragonal undoped sample should not be superconducting at all. Our results corroborate previous findings of Topnikov [JETP Lett. 46, 577 (1987......)] of a tetragonal superconducting YBCO crystal with x=0.62....

Gradient stress induced coexistence of tetragonal and rhombohedral phases in Pb(Zr,Ti)O3 films

International Nuclear Information System (INIS)

Li Liben; Chen Qingdong; Li Xinzhong; Hu Zhixiang; Zhen Zhiqiang

2009-01-01

Thermodynamic theory has been used to explain quantitatively the coexistence of tetragonal and rhombohedral phases in Zr-rich Pb(Zr, Ti)O 3 (PZT) films grown on a compressive substrate. The key is to consider a set of gradient thermal stresses imposed on the films. The 'stress-temperature' phase diagrams were developed for PZT films of several different compositions (Ti/Zr=20/80, 30/70, 40/60, 50/50). The characteristic feature of the phase diagrams for Zr-rich PZT films is the coexistence of tetragonal and rhombohedral phases in the compressive stress region. The volume fractions of the rhombohedral phase were calculated for the Zr-rich PZT films grown on MgO substrate. The result agrees with the experiment.

Synthesis and ferroelectric properties of rare earth compounds with tungsten bronze-type structure

Energy Technology Data Exchange (ETDEWEB)

Bouziane, M., E-mail: bouzianemeryem@yahoo.fr [Laboratoire de Chimie du Solide Appliquee, Faculte des Sciences, Avenue Ibn Batouta, BP 1014, Rabat (Morocco); Taibi, M. [Laboratoire de Physico-Chimie des Materiaux, LAF 502, Ecole Normale Superieure, BP 5118, Rabat (Morocco); Boukhari, A. [Laboratoire de Chimie du Solide Appliquee, Faculte des Sciences, Avenue Ibn Batouta, BP 1014, Rabat (Morocco)

2011-10-03

Highlights: {center_dot} Polycrystalline materials with the tungsten bronze-type structure have been synthesized and characterized. {center_dot} Effect of the incorporation of rare earth ions and paramagnetic cations (Fe{sup 3+}) into a matrix ferroelectrically active was studied. {center_dot} Ferroelectric transition is pronounced by a large thermal hysteresis during the heating and cooling cycles. {center_dot} Phase transitions around T{sub c} were confirmed by differential scanning calorimetry (DSC) measurements. - Abstract: Polycrystalline materials with a general formula Pb{sub 2}Na{sub 0.8}R{sub 0.2}Nb{sub 4.8}Fe{sub 0.2}O{sub 15} (R = Dy, Eu, Sm, Nd, La) have been synthesized, in air by a high temperature solid state reaction method. X-ray diffraction study, at room temperature, revealed that they crystallize in the tungsten bronze-type structure. Dielectric properties were performed, in the temperature range 25-500 deg. C, at three different frequencies 10, 100 and 1000 kHz. The ferroelectric transition is pronounced by a large thermal hysteresis during the heating and cooling cycles. The determined Curie temperature values T{sub c} were discussed as a function of rare earth size. Phase transitions around T{sub c} for the investigated compounds were confirmed by differential scanning calorimetry (DSC) measurements.

Genetic characteristics and migration history of a bronze culture population in the West Liao-River valley revealed by ancient DNA.

Science.gov (United States)

Li, Hongjie; Zhao, Xin; Zhao, Yongbin; Li, Chunxiang; Si, Dayong; Zhou, Hui; Cui, Yinqiu

2011-12-01

In order to study the genetic characteristics of the Lower Xiajiadian culture (LXC) population, a main bronze culture branch in northern China dated 4500-3500 years ago, two uniparentally inherited markers, mitochondrial DNA and Y-chromosome single-nucleotide polymorphisms (Y-SNPs), were analyzed on 14 human remains excavated from the Dadianzi site. The 14 sequences, which contained 13 haplotypes, were assigned to 9 haplogroups, and Y-SNP typing of 5 male individuals assigned them to haplogroups N (M231) and O3 (M122). The results indicate that the LXC population mainly included people carrying haplogroups from northern Asia who had lived in this region since the Neolithic period, as well as genetic evidence of immigration from the Central Plain. Later in the Bronze Age, part of the population migrated to the south away from a cooler climate, which ultimately influenced the gene pool in the Central Plain. Thus, climate change is an important factor, which drove the population migration during the Bronze Age in northern China. Based on these results, the local genetic continuity did not seem to be affected by outward migration, although more data are needed especially from other ancient populations to determine the influence of return migration on genetic continuity.

Monumental megalithic burial and rock art tell a new story about the Levant Intermediate Bronze "Dark Ages".

Science.gov (United States)

Sharon, Gonen; Barash, Alon; Eisenberg-Degen, Davida; Grosman, Leore; Oron, Maya; Berger, Uri

2017-01-01

The Intermediate Bronze Age (IB) in the Southern Levant (ca. 2350-2000 BCE) is known as the "Dark Ages," following the collapse of Early Bronze urban society and predating the establishment of the Middle Bronze cities. The absence of significant settlements and monumental building has led to the reconstruction of IB social organization as that of nomadic, tribal society inhabiting rural villages with no central governmental system. Excavation in the Shamir Dolmen Field (comprising over 400 dolmens) on the western foothills of the Golan Heights was carried out following the discovery of rock art engravings on the ceiling of the central chamber inside one of the largest dolmens ever recorded in the Levant. Excavation of this multi-chambered dolmen, covered by a basalt capstone weighing some 50 tons, revealed a secondary multi-burial (of both adults and children) rarely described in a dolmen context in the Golan. Engraved into the rock ceiling above the multi-burial is a panel of 14 forms composed of a vertical line and downturned arc motif. 3D-scanning by structured-light technology was used to sharpen the forms and revealed the technique employed to create them. Building of the Shamir dolmens required a tremendous amount of labor, architectural mastery, and complex socio-economic organization well beyond the capacity of small, rural nomadic groups. The monumental megalithic burial of the Shamir dolmens indicates a hierarchical, complex, non-urban governmental system. This new evidence supports a growing body of recent criticism stemming from new discoveries and approaches that calls for rethinking our views of the Levantine IB "Dark Ages."

Social change in ‘Phoenicia’ in the late Bronze/early Iron Age transition

OpenAIRE

Boyes, Philip

2013-01-01

This dissertation explores social, cultural and political changes in the region later known as ‘Phoenicia’ during the period of approximately 1300-900 BC. By applying modern approaches to theoretical questions such as the nature of social change, identity, migration and how such phenomena are represented in the archaeological record, this dissertation aims to provide a discussion of Late Bronze/Early Iron Age Phoenicia based on a more solid methodological foundation than has of...

Moessbauer effect study of hyperfine interaction of /sup 161/Dy and /sup 151/Eu in tungsten bronzes Dysub(0. 18) WO/sub 3/ and Eusub(0. 18) WO/sub 3/

Energy Technology Data Exchange (ETDEWEB)

Kisynska, K

1979-01-01

The Moessbauer technique was used to investigate the hyperfine interaction of /sup 161/Dy and /sup 151/Eu in cubic rare earth tungsten bronzes: Dysub(0.18)WO/sub 3/ and Eusub(0.18)WO/sub 3/. Well resolved hfs spectrum was obtained at 4.2 K for Dysub(0.18)WO/sub 3/. The effective hf field approximation sufficed to interpret the spectrum. The obtained hyperfine interaction parameters were: -g/sub 0/..beta..sub(N)Hsub(eff)=(805+-19) Mc/s and e/sup 2/qQ/sub 0//4 = (506+-56) Mc/s. These results imply that ground doublet of Dy/sup +3/ ion in bronze is a Kramers doublet Vertical Bar+-15/2> with asymmetrical hyperfine tensor Asub(z) non equal to 0, Asub(x) = Asub(y) = 0 and that local crystalline field at RE metal in tungsten bronze at 4.2 K cannot be cubic. From ME absorption spectra of Eusub(0.18)WO/sub 3/ taken at 4.2 K, 78 K and 300 K the values of quadrupole interaction constants for bronze lattice and its temperature dependence were obtained. These data indicate that a phase transition from the high temperature ideal perovskite structure to a distorted one occurs in RE bronzes and that the distortion concerns the nearest tungsten-oxygen environment of RE ion.

Joining of yttria-tetragonal zirconia polycrystal with an aluminum-zirconium alloy

International Nuclear Information System (INIS)

Rathner, R.C.; Green, D.J.

1990-01-01

Specimens of yttria-tetragonal zirconia polycrystal (Y-TZP) have been joined with an Al-5.8 wt% Zr alloy at temperatures of 900 degrees C and above. The braze alloy contained large needlelike precipitates of the intermetallic phase Al 3 Sr. It is shown that these large precipitates can aid in strengthening of the joint, especially if they are close to the interface. With decreasing layer thickness, the strengths increased with values as high as 420 MPa

The detailed orbital-decomposed electronic structures of tetragonal ZrO2

International Nuclear Information System (INIS)

Zhang, Yan; Ji, Vincent; Xu, Ke-Wei

2013-01-01

The detailed orbital-decomposed electronic structures of the tetragonal zirconia have been investigated by using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation (GGA) as well as taking into account the on-site Coulomb repulsive interaction (GGA+U). The deviation of the minimization energy from d z =0 to d z =±0.032 for experimental lattice constants (a=3.605 Å and c=5.180 Å) confirms the alternating displacement of the oxygen atoms, which causes half of the Zr---O bonds stronger and the other half weaker compared with the bonds in symmetric (d z =0) zirconia. The distorted tetragonal environment of the eight oxygen anions around Zr site splits the five-fold degenerate d states of a free Zr atom into triply degenerate t 2g (d xy , d yz and d zx ) states and doubly degenerate e g (d z 2 and d x 2 -y 2 ) states. The additional covalent character upon Zr-O ionic bonds are resulted from the hybridization between the O(2s), O(2p) and Zr(5s), triply degenerate t 2g (d xy , d yz and d zx ) states of Zr(4d). The O(2s) and O(2p) states are clearly separated and no hybrid bonding states are formed

The tetragonal-monoclinic transformations of zirconia studied by small angle neutron scattering and differential thermal analysis

International Nuclear Information System (INIS)

Li, Z.; Epperson, J.E.; Fang, Y.; Chan, S.K.

1992-08-01

The tetragonal-monoclinic transformations of zirconia have been studied on pristine single crystals and on their cycled crystallites. Two complementary techniques have been used. Small angle neutron scattering experiments were carried out to monitor the degree of completion of a transformation under equilibrium conditions for collections of 20--30 large crystals using the total internal and external surface area as an indicator. Differential thermal analysis experiments were carried out on smaller single-domain crystals of different sizes individually during heating and cooling to measure the rates of latent heat absorption and emission. The investigation establishes the upper limit of stability of the monoclinic phase, the lower limit of stability of the tetragonal phase, and the coexistence temperature between the two phases. The characteristics of the transformations are also inferred from these experiments

Human manipulative behavior in the Central European Late Eneolithic and Early Bronze Age: humeral bilateral asymmetry

Czech Academy of Sciences Publication Activity Database

Sládek, Vladimír; Berner, M.; Sosna, D.; Sailer, R.

2007-01-01

Roč. 133, č. 1 (2007), s. 669-681 ISSN 0002-9483 R&D Projects: GA ČR GP206/01/D018 Institutional research plan: CEZ:AV0Z60930519 Keywords : cross-sectional geometry * biomechanics * humerus * handedness * Eneolithic * Bronze Age Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 2.273, year: 2007

Electronic band structure and charge density wave transition in quasi-2D KMo{sub 6}O{sub 17} purple bronze

Energy Technology Data Exchange (ETDEWEB)

Valbuena, M A [Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid (Spain); Avila, J; Asensio, M C [Synchrotron SOLEIL, L' Orme des Merisiers, Saint-Aubin, B.P. 48, 91192 Gif-sur-Yvette Cedex (France); Vyalikh, D V; Laubschat, C; Molodtsov, S L [Institut fuer Festkoerperphysik, Technische Universitaet Dresden, D-01062 Dresden (Germany); Guyot, H [LEPES, CNRS, BP 166, 38042 Grenoble Cedex 9 (France)], E-mail: mvbuena@icmm.csic.es

2008-03-15

High resolution angle-resolved photoemission of quasi-2D KMo{sub 6}O{sub 17} purple bronze has been performed in the range from room temperature to 130 K, slightly above the charge density wave (CDW) transition (T{sub c} = 110 K), and down to 35 K (well below T{sub c}). In this paper we report a detailed study of how electronic band structure is affected by this transition driven by the hidden nesting scenario. The expected spectroscopic fingerprints of the CDW phase transition have been found and discussed according to the hidden one dimension and the development of a quasi-commensurate CDW. The excellent agreement between theory and our experimental results makes of potassium purple bronze a reference system for studying this type of instabilities.

Crystal structure of red lead titanate thin films

Energy Technology Data Exchange (ETDEWEB)

Bursill, L.A.; Peng, J.L.; Jiang, B. [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Li, X. [Jilin Univ., Changchun, JL (China). Dept of Chemistry

1998-09-01

Orange-red lead titanate thin films are examined by high-resolution transmission electron microscopy and diffraction. It is remarkable that the structure is based on that of tetragonal-tungsten-bronze (TTB) rather than perovskite-type. The chemical basis for this result is examined. It is deduced that the TTB structure is stabilized by inclusion of hydroxyl ions during synthesis by a sol-gel route involving hydrolysis of n-Butyl titanate 7 refs., 1 tab., 4 figs.

Tetragonal phase in Al-rich region of U-Fe-Al system

International Nuclear Information System (INIS)

Meshi, L.; Zenou, V.; Ezersky, V.; Munitz, A.; Talianker, M.

2005-01-01

A new ternary aluminide U 2 FeAl 20 with the approximate composition Al-4.2at% Fe-8.5at% U was observed in the Al-rich corner of the U-Al-Fe system. Transmission electron microscopy and electron microdiffraction technique were used for characterization of the structure of this phase. It has a tetragonal unit cell with the parameters a=12.4A and c=10.3A and can be described by the space group I4-bar 2m

BRONZ KATKILI POLİ-TETRA-FLOR-ETİLEN (PTFE) KOMPOZİTLERİN PASLANMAZ ÇELİK MALZEMEYE KARŞI AŞINMA VE SÜRTÜNME DAVRANIŞLARI

OpenAIRE

Ünal, Hüseyin; Yetkin, Salih Hakan; Poyraz, Bayram

2018-01-01

Bu deneysel çalışmada, katkısızpoli-tetra-flor-etilen (PTFE) polimeri ile %25 bronz katkılı PTFE kompoziti ve%40 bronz katkılı PTFE kompozitlerin, kuru kayma şartları altında paslanmazçelik malzemeye karşı tribolojik performansları incelenmiştir. Tribolojiktestler, pim-disk aşınma cihazında ve oda sıcaklığında gerçekleştirilmiştir.Aşınma ve sürtünme testleri, 50N, 100N ve 150N yüklerde ve 1.0, 1.5 ve 2.0m/skayma hızlarında yapılmıştır. Aşınma test sonuçlarına göre, %40 bronz katkılıPTFE kompo...

Fast polarization mechanisms in the uniaxial tungsten-bronze relaxor strontium barium niobate SBN-81

Czech Academy of Sciences Publication Activity Database

Buixaderas, Elena; Kadlec, Christelle; Kempa, Martin; Bovtun, Viktor; Savinov, Maxim; Bednyakov, Petr; Hlinka, Jiří; Dec, J.

2017-01-01

Roč. 7, Dec (2017), s. 1-11, č. článku 18034. ISSN 2045-2322 R&D Projects: GA ČR GA16-09142S; GA MŠk(CZ) LD15014 Institutional support: RVO:68378271 Keywords : relaxor * tungsten-bronzes * dielectric response * phonons * broad-band spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 4.259, year: 2016

Integrated analytical methodologies for the study of corrosion processes in archaeological bronzes

Energy Technology Data Exchange (ETDEWEB)

Alberghina, Maria Francesca; Barraco, Rosita; Brai, Maria; Schillaci, Tiziano, E-mail: tschillaci@unipa.it; Tranchina, Luigi

2011-02-15

The investigations on structure and micro-chemical composition of archaeological metal alloys are needed in archaeometry. The aim of this study is devoted both to acquire information about their provenance and production technology, and to improve our understanding about the corrosion processes. In this paper we present the study of the corrosion phenomena of bronze samples, laboratory-made according to binary, ternary and quaternary alloys typical of Roman archaeometallurgical production through an integrated methodology based on the use of non or micro invasive physical techniques. Among the analysed samples, two were artificially aged through burial in the archaeological site of Tharros, along the west coast of Sardinia (Italy). The corrosion products, typical of the bronzes in archaeological sites near the sea, have been characterized by non invasive and micro-destructive measurements. In particular, the corrosion patinas were examined through optical microscopy, scanning electron microscopy and microanalysis, X-ray fluorescence and laser ablation spectroscopy. The use of integrated technologies allowed us to determine both the elemental composition and surface morphology of the patina, highlighting the correlation between patina nature and chemical composition of the burial context. Moreover, data obtained by the laser-induced breakdown spectroscopy along the depth profile on the samples, have yielded information about the stratigraphic layers of corrosion products and their growth. Finally, the depth profiles allowed us to verify both the chemical elements constituting the patina, the metal ions constituting the alloy and the occurrence of migration phenomena from bulk to the surface.

Integrated analytical methodologies for the study of corrosion processes in archaeological bronzes

International Nuclear Information System (INIS)

Alberghina, Maria Francesca; Barraco, Rosita; Brai, Maria; Schillaci, Tiziano; Tranchina, Luigi

2011-01-01

The investigations on structure and micro-chemical composition of archaeological metal alloys are needed in archaeometry. The aim of this study is devoted both to acquire information about their provenance and production technology, and to improve our understanding about the corrosion processes. In this paper we present the study of the corrosion phenomena of bronze samples, laboratory-made according to binary, ternary and quaternary alloys typical of Roman archaeometallurgical production through an integrated methodology based on the use of non or micro invasive physical techniques. Among the analysed samples, two were artificially aged through burial in the archaeological site of Tharros, along the west coast of Sardinia (Italy). The corrosion products, typical of the bronzes in archaeological sites near the sea, have been characterized by non invasive and micro-destructive measurements. In particular, the corrosion patinas were examined through optical microscopy, scanning electron microscopy and microanalysis, X-ray fluorescence and laser ablation spectroscopy. The use of integrated technologies allowed us to determine both the elemental composition and surface morphology of the patina, highlighting the correlation between patina nature and chemical composition of the burial context. Moreover, data obtained by the laser-induced breakdown spectroscopy along the depth profile on the samples, have yielded information about the stratigraphic layers of corrosion products and their growth. Finally, the depth profiles allowed us to verify both the chemical elements constituting the patina, the metal ions constituting the alloy and the occurrence of migration phenomena from bulk to the surface.

Curly malachite on archaeological bronze : A systematic study of the shape and phenomenological approach of its formation mechanism

NARCIS (Netherlands)

Nienhuis, J.; Robbiola, Luc; Giuliani, Roberta; Joosten, Ineke; Huisman, Hans; van Os, Bertil; Sietsma, J.

2016-01-01

Curly malachite (CM) is found as a green cupric carbonate hydroxide corrosion product on archaeological bronze, mostly on artefacts retrieved from graves. In this paper, a morphological characterization approach is proposed, enabling the investigation of the formation process of CM. It is suggested

Effect of strain on the martensitic phase transition in superconducting Nb3Sn

International Nuclear Information System (INIS)

Hoard, R.W.; Scanlan, R.M.; Smith, G.S.; Farrell, C.L.

1980-01-01

The connection between the cubic-to-tetragonal martensitic phase transformation and the phenomenon of superconductivity in A15 compounds is being investigated. The degradation of the critical parameters, such as T/sub c/, H/sub c2/, and J/sub c/, with mechanical straining is of particular interest. Low-temperature x-ray diffraction experiments are performed on Nb 3 Sn ribbons (with the bronze layers etched off) mounted on copper and indium sample stages. The cryostat used is unique in that it has a vacuum mechanical insert which allows the superconductor to be placed under both compressive and tensile strains while at low temperatures. Preliminary results indicate that the martensitic phase transition temperature, T/sub m/, increases with compressive strains. Other effects of strain on tetragonal phase production are also discussed

First Paleoparasitological Report on the Animal Feces of Bronze Age Excavated from Shahr-e Sukhteh, Iran.

Science.gov (United States)

Makki, Mahsasadat; Dupouy-Camet, Jean; Sajjadi, Seyed Mansour Seyed; Naddaf, Saied Reza; Mobedi, Iraj; Rezaeian, Mostafa; Mohebali, Mehdi; Mowlavi, Gholamreza

2017-04-01

Shahr-e Sukhteh (meaning burnt city in Persian) in Iran is an archeological site dated back to around 3,200-1,800 BC. It is located in Sistan and Baluchistan Province of Iran and known as the junction of Bronze Age trade routes crossing the Iranian plateau. It was appointed as current study area for paleoparasitological investigations. Excavations at this site have revealed various archeological materials since 1967. In the present study, sheep and carnivore coprolites excavated from this site were analyzed by means of rehydration technique using TSP solution for finding helminth eggs. Dicrocoelium dendriticum, Capillaria sp., and Taenia sp. eggs were identified, while some other objects similar to Anoplocephalidae and Toxocara spp. eggs were also retrieved from the samples but their measured parameters did not match those of these species. The present paper illustrates the first paleoparasitological findings of Bronze Age in eastern Iran supporting the economic activities, peopling, and communication as well as the appropriate condition for zoonotic helminthiasis life cycle in Shahr-e Sukhteh archeological site.

Exchange anisotropy as a probe of antiferromagnetism in expanded face-centered-tetragonal Mn(001) layers

NARCIS (Netherlands)

Kohlhepp, J.T.; Wieldraaijer, H.; Jonge, de W.J.M.

2006-01-01

Manganese (Mn) grows coherent and with an expanded metastable face-centered-tetragonal (e-fct) structure on ultrathin fct Co(001)/Cu(001) template layers. From the temp. dependence of the obsd. unidirectional Mn/Co interface exchange anisotropy, an antiferromagnetic state with a blocking temp.

The Agricultural Landscape of Tel Burna: Ecology and Economy of a Bronze Age/Iron Age Settlement in the Southern Levant

Directory of Open Access Journals (Sweden)

Orendi Andrea

2017-12-01

Full Text Available The Shephelah, known as the breadbasket of the southern Levant, is one of the more extensively investigated regions of the southern Levant in terms of archaeobotanical research. However, studies dealing with agriculture are scarce in comparison to the archaeobotanical data available. The analysis of the archaeobotanical assemblage in combination with the archaeological remains from Tel Burna will contribute to the investigation of the agriculture of the Shephelah. Several seasons of excavation revealed a cultic complex dating to the Late Bronze Age and an Iron Age II settlement with various agricultural installations such as silos and wine or olive presses. In this paper, we present the agricultural features in conjunction with the systematical archaeobotanical sampling, which enables us to reconstruct the types of crop plants cultivated at the site. Grass pea seeds dominate the assemblage collected from the Late Bronze Age complex, which may point to a connection to the Aegean. The Iron Age assemblage is distinguished by a significantly broad range of crop plants which were cultivated in vicinity of the tell. The archaeological Iron Age remains indicate that the processing of secondary products such as olive oil, wine, or textiles took place within the Iron Age settlement of Tel Burna. This first comprehensive overview describes the character of agricultural production in the Late Bronze Age to Iron Age environmental and geopolitical transformations.

Monumental megalithic burial and rock art tell a new story about the Levant Intermediate Bronze "Dark Ages".

Directory of Open Access Journals (Sweden)

Gonen Sharon

Full Text Available The Intermediate Bronze Age (IB in the Southern Levant (ca. 2350-2000 BCE is known as the "Dark Ages," following the collapse of Early Bronze urban society and predating the establishment of the Middle Bronze cities. The absence of significant settlements and monumental building has led to the reconstruction of IB social organization as that of nomadic, tribal society inhabiting rural villages with no central governmental system. Excavation in the Shamir Dolmen Field (comprising over 400 dolmens on the western foothills of the Golan Heights was carried out following the discovery of rock art engravings on the ceiling of the central chamber inside one of the largest dolmens ever recorded in the Levant. Excavation of this multi-chambered dolmen, covered by a basalt capstone weighing some 50 tons, revealed a secondary multi-burial (of both adults and children rarely described in a dolmen context in the Golan. Engraved into the rock ceiling above the multi-burial is a panel of 14 forms composed of a vertical line and downturned arc motif. 3D-scanning by structured-light technology was used to sharpen the forms and revealed the technique employed to create them. Building of the Shamir dolmens required a tremendous amount of labor, architectural mastery, and complex socio-economic organization well beyond the capacity of small, rural nomadic groups. The monumental megalithic burial of the Shamir dolmens indicates a hierarchical, complex, non-urban governmental system. This new evidence supports a growing body of recent criticism stemming from new discoveries and approaches that calls for rethinking our views of the Levantine IB "Dark Ages."

Qualitative and quantitative laser-induced breakdown spectroscopy of bronze objects

International Nuclear Information System (INIS)

Tankova, V; Blagoev, K; Grozeva, M; Malcheva, G; Penkova, P

2016-01-01

Laser-induced breakdown spectroscopy (LIBS) is an analytical technique for qualitative and quantitative elemental analysis of solids, liquids and gases. In this work, the method was applied for investigation of archaeological bronze objects. The analytical information obtained by LIBS was used for qualitative determination of the elements in the material used for manufacturing of the objects under study. Quantitative chemical analysis was also performed after generating calibration curves with standard samples of similar matrix composition. Quantitative estimation of the elemental concentration of the bulk of the samples was performed, together with investigation of the surface layer of the objects. The results of the quantitative analyses gave indications about the manufacturing process of the investigated objects. (paper)

Performance evaluation of grid-enabled registration algorithms using bronze-standards

CERN Document Server

Glatard, T; Montagnat, J

2006-01-01

Evaluating registration algorithms is difficult due to the lack of gold standard in most clinical procedures. The bronze standard is a real-data based statistical method providing an alternative registration reference through a computationally intensive image database registration procedure. We propose in this paper an efficient implementation of this method through a grid-interfaced workflow enactor enabling the concurrent processing of hundreds of image registrations in a couple of hours only. The performances of two different grid infrastructures were compared. We computed the accuracy of 4 different rigid registration algorithms on longitudinal MRI images of brain tumors. Results showed an average subvoxel accuracy of 0.4 mm and 0.15 degrees in rotation.

Shape and phase evolution from CsPbBr3 perovskite nanocubes to tetragonal CsPb2Br5 nanosheets with an indirect bandgap.

Science.gov (United States)

Li, Guopeng; Wang, Hui; Zhu, Zhifeng; Chang, Yajing; Zhang, Ting; Song, Zihang; Jiang, Yang

2016-09-13

Tetragonal CsPb 2 Br 5 nanosheets were obtained by an oriented attachment of orthorhombic CsPbBr 3 nanocubes, involving a lateral shape evolution from octagonal to square. Meanwhile, the experimental results, together with DFT simulation results, indicated that the tetragonal CsPb 2 Br 5 is an indirect bandgap semiconductor that is PL-inactive with a bandgap of 2.979 eV.

Designing magnetic compensated states in tetragonal Mn{sub 3}Ge-based Heusler alloys

Energy Technology Data Exchange (ETDEWEB)

You, Yurong; Xu, Guizhou, E-mail: gzxu@njust.edu.cn; Hu, Fang; Gong, Yuanyuan; Liu, Er; Peng, Guo; Xu, Feng, E-mail: xufeng@njust.edu.cn

2017-05-01

Magnetic compensated materials attracted much interests due to the observed large exchange bias and large coercivity, and also their potential applications in the antiferromagnetic spintronics with merit of no stray field. In this work, by using ab-initio studies, we designed several Ni (Pd, Pt) doped Mn{sub 3}Ge-based D0{sub 22}-type tetragonal Heusler alloys with fully compensated states. Theoretically, we find the total moment change is asymmetric across the compensation point (at ~x=0.3) in Mn{sub 3-x}Y{sub x}Ge (Y=Ni, Pd, Pt). In addition, an uncommon discontinuous jump is observed across the critical zero-moment point, indicating that some non-trivial properties may emerge at this point. Further electronic analyses of these compensated alloys reveal high spin polarizations at the Fermi level, which is advantageous for spin transfer torque applications. - Highlights: • Several new fully compensated magnetic states are identified in Mn{sub 3}Ge-based tetragonal alloys. • The magnetic moment changes are asymmetric upon Ni, Pd and Pt substitution. • Discontinuous jumps exist across the compensated points. • The three compensated alloys possess large spin polarizations.

Atomic Origins of Monoclinic-Tetragonal (Rutile) Phase Transition in Doped VO 2 Nanowires

KAUST Repository

Asayesh-Ardakani, Hasti

2015-10-12

There has been long-standing interest in tuning the metal-insulator phase transition in vanadium dioxide (VO) via the addition of chemical dopants. However, the underlying mechanisms by which doping elements regulate the phase transition in VO are poorly understood. Taking advantage of aberration-corrected scanning transmission electron microscopy, we reveal the atomistic origins by which tungsten (W) dopants influence the phase transition in single crystalline WVO nanowires. Our atomically resolved strain maps clearly show the localized strain normal to the (122¯) lattice planes of the low W-doped monoclinic structure (insulator). These strain maps demonstrate how anisotropic localized stress created by dopants in the monoclinic structure accelerates the phase transition and lead to relaxation of structure in tetragonal form. In contrast, the strain distribution in the high W-doped VO structure is relatively uniform as a result of transition to tetragonal (metallic) phase. The directional strain gradients are furthermore corroborated by density functional theory calculations that show the energetic consequences of distortions to the local structure. These findings pave the roadmap for lattice-stress engineering of the MIT behavior in strongly correlated materials for specific applications such as ultrafast electronic switches and electro-optical sensors.

Atomic Origins of Monoclinic-Tetragonal (Rutile) Phase Transition in Doped VO 2 Nanowires

KAUST Repository

Asayesh-Ardakani, Hasti; Nie, Anmin; Marley, Peter M.; Zhu, Yihan; Phillips, Patrick J.; Singh, Sujay; Mashayek, Farzad; Sambandamurthy, Ganapathy; Low, Ke Bin; Klie, Robert F.; Banerjee, Sarbajit; Odegard, Gregory M.; Shahbazian-Yassar, Reza

2015-01-01

There has been long-standing interest in tuning the metal-insulator phase transition in vanadium dioxide (VO) via the addition of chemical dopants. However, the underlying mechanisms by which doping elements regulate the phase transition in VO are poorly understood. Taking advantage of aberration-corrected scanning transmission electron microscopy, we reveal the atomistic origins by which tungsten (W) dopants influence the phase transition in single crystalline WVO nanowires. Our atomically resolved strain maps clearly show the localized strain normal to the (122¯) lattice planes of the low W-doped monoclinic structure (insulator). These strain maps demonstrate how anisotropic localized stress created by dopants in the monoclinic structure accelerates the phase transition and lead to relaxation of structure in tetragonal form. In contrast, the strain distribution in the high W-doped VO structure is relatively uniform as a result of transition to tetragonal (metallic) phase. The directional strain gradients are furthermore corroborated by density functional theory calculations that show the energetic consequences of distortions to the local structure. These findings pave the roadmap for lattice-stress engineering of the MIT behavior in strongly correlated materials for specific applications such as ultrafast electronic switches and electro-optical sensors.

Absolute dating of the Aegean Late Bronze Age

International Nuclear Information System (INIS)

Warren, P.M.

1987-01-01

A recent argument for raising the absolute date of the beginning of the Aegean Late Bronze (LB) Age to about 1700 B.C. is critically examined. It is argued here that: (1) the alabaster lid from Knossos did have the stratigraphical context assigned to it by Evans, in all probability Middle Minoan IIIA, c. 1650 B.C.; (2) the attempt to date the alabastron found in an early Eighteenth Dynasty context at Aniba to Late Minoan IIIA:1 is open to objections; (3) radiocarbon dates from Aegean LB I contexts are too wide in their calibrated ranges and too inconsistent both within and between site sets to offer any reliable grounds at present for raising Aegean LB I absolute chronology to 1700 B.C. Other evidence, however, suggests this period began about 1600 B.C., i.e. some fifty years earlier than the conventional date of 1550 B.C. (author)

Theoretical and experimental evaluation of piezo-optic parameters and photoelastic constant in tetragonal PWO.

Science.gov (United States)

Natali, Pier Paolo; Montalto, Luigi; Daví, Fabrizio; Mengucci, Paolo; Ciriaco, Andrea; Paone, Nicola; Rinaldi, Daniele

2018-02-01

The tetragonal PbWO 4 (PWO) is one of the most important scintillating crystals, being used both in the Compact Muon Solenoid (CMS) experiment at the European Organization for Nuclear Research (CERN) and in the PANDA project at the Facility for Antiproton and Ion Research (FAIR). Light yield and other relevant scintillation properties depend, among many factors, also on the crystal mechanical quality. Accordingly, a detailed knowledge of crystal piezo-optic properties is a mandatory step toward understanding elasto-optic behavior and performing crystal quality control. In this paper, we evaluate for the first time, to the best of our knowledge, by means of both photoelastic and x-ray measurements, some components of the piezo-optic tensor; moreover, when the crystal is acted upon by a uniaxial stress, we obtain an evaluation for the rotation angle of the optic plane under stress as well as the photoelastic constant. These parameters are necessary to detect the residual stresses within the crystal, if any, and to give an overall quality measure. Such a methodology is in general suitable for any tetragonal crystals.

Pressure-induced change of the electronic state in the tetragonal phase of CaFe2As2

International Nuclear Information System (INIS)

Sakaguchi, Yui; Ikeda, Shugo; Kuse, Tetsuji; Kobayashi, Hisao

2014-01-01

We have investigated the electronic states of single-crystal CaFe 2 As 2 under hydrostatic pressure using 57 Fe Mössbauer spectroscopy and magnetization measurements. The center shift and the quadrupole splitting were refined from observed 57 Fe Mössbauer spectra using the single-crystalline sample under pressure at room temperature. A discontinuous decrease in the pressure dependence of the refined center shift was observed at 0.33 GPa without any anomaly in the pressure dependence of the refined quadrupole splitting, indicating a purely electronic state change in CaFe 2 As 2 with a tetragonal structure. Such a change is shown to be reflected in the peak-like anomalies observed in the pressure dependences of the magnetic susceptibility at 0.26 GPa above 150 K. Our results reveal that this pressure-induced electronic state change suppresses the tetragonal-to-orthorhombic structural phase transition accompanied by an antiferromagnetic ordering. We further observed superconductivity in CaFe 2 As 2 below ∼8 K around 0.33 GPa although our sample was not in a single phase at this pressure. These findings suggest that the electronic state change observed in CaFe 2 As 2 with the tetragonal structure is relevant to the appearance of the pressure-induced superconductivity in AFe 2 As 2 . (paper)

Piety, Practice, and Politics: Agency and Ritual in the Late Bronze Age Southern Levant

OpenAIRE

DePietro, Dana Douglas

2012-01-01

Striking changes in the archaeological record of the southern Levant during the final years of the Late Bronze Age have long fascinated scholars interested in the region and period. Attempts to explain the emergence of new forms of Canaanite material culture have typically cited external factors such as Egyptian political domination as the driving force behind culture change, relying on theoretical models of acculturation, elite-emulation and center-periphery theory. While these approaches ca...

Tetragonal-cubic phase boundary in nanocrystalline ZrO2-Y2O3 solid solutions synthesized by gel-combustion

International Nuclear Information System (INIS)

Fabregas, Ismael O.; Craievich, Aldo F.; Fantini, Marcia C.A.; Millen, Ricardo P.; Temperini, Marcia L.A.; Lamas, Diego G.

2011-01-01

Research highlights: → Gel-combustion synthesis yields compositionally homogeneous, single-phased ZrO 2 -Y 2 O 3 nanopowders, that exhibit the presence at room temperature of three different phases depending on Y 2 O 3 content, namely two tetragonal forms (t' and t'') and the cubic phase. → Phase identification can be achieved by synchrotron XPD (SXPD) and Raman spectroscopy since the tetragonal forms and the cubic phase can be distinguished by these techniques. → The crystallographic features of ZrO 2 -Y 2 O 3 nanopowders were determined by SXPD. They are similar to those reported by Yashima and coworkers for compositionally homogeneous materials containing larger (micro)crystals. However, the lattice parameters are slightly different and the axial ratios c/a of our t' samples are smaller than those reported by these authors. → Compositional t'/t'' and t''/cubic phase boundaries are located at (9 ± 1) and (10.5 ± 0.5) mol% Y 2 O 3 , respectively. → For the whole series of nanocrystalline ZrO 2 -Y 2 O 3 solid solutions studied in the present work, no evidences of the presence of a mixture of phases - as reported by Yashima and coworkers for microcrystalline solid solutions - were detected. - Abstract: By means of synchrotron X-ray powder diffraction (SXPD) and Raman spectroscopy, we have detected, in a series of nanocrystalline and compositionally homogeneous ZrO 2 -Y 2 O 3 solid solutions, the presence at room temperature of three different phases depending on Y 2 O 3 content, namely two tetragonal forms and the cubic phase. The studied materials, with average crystallite sizes within the range 7-10 nm, were synthesized by a nitrate-citrate gel-combustion process. The crystal structure of these phases was also investigated by SXPD. The results presented here indicate that the studied nanocrystalline ZrO 2 -Y 2 O 3 solid solutions exhibit the same phases reported in the literature for compositionally homogeneous materials containing larger (micro

Synthesis and crystal structure of Mg2B24C, a new boron-rich boride related to 'tetragonal boron I'

International Nuclear Information System (INIS)

Adasch, Volker; Hess, Kai-Uwe; Ludwig, Thilo; Vojteer, Natascha; Hillebrecht, Harald

2006-01-01

Single crystals of Mg 2 B 24 C, a new boron-rich boridecarbide of magnesium, were synthesized as black needles and columns by reaction of the elements in Ta ampoules and BN crucibles at 1300 deg. C. The crystal structure was determined by X-ray diffraction (P-4n2, a=8.9391(13)A, c=5.0745(10)A, Z=2, 713 reflections, 64 variables, R 1 (F)=0.0235, wR 2 (I)=0.0591). It is closely related to 'tetragonal boron I' and can be described as a tetragonal rod packing of corner-linked B 12 icosahedra with C and Mg atoms in the voids. Each B 12 icosahedron has 2 B-C bonds and 10 exohedral bonds to other icosahedra, 2 within the rod and 4x2 to neighbouring rods. The isolated C atoms are 4-fold coordinated forming distorted tetrahedra. Mg is placed on two crystallographically independent positions within the three-dimensional B 12 C network. Mg 2 B 24 C is the first example for a compound related to 'tetragonal boron I' with a stoichiometric composition

Behavior of the monophosphate tungsten bronzes (PO2)4(WO3)2m (m = 7 and 8) in the course of electrochemical lithium insertion

International Nuclear Information System (INIS)

Martinez-de la Cruz, A.; Longoria Rodriguez, F.E.; Gonzalez, Lucy T.; Torres-Martinez, Leticia M.

2007-01-01

The electrochemical lithium insertion process has been studied in the family of monophosphate tungsten bronzes (PO 2 ) 4 (WO 3 ) 2m , where m = 7 and 8. Structural changes in the pristine oxides were followed as lithium insertion proceeded. Through potentiostatic intermittent technique the different processes which take place in the cathode during the discharge of the cell were analyzed. The nature of the bronzes Li x (PO 2 ) 4 (WO 3 ) 2m formed was determined by in situ X-ray diffraction experiments. These results have allowed establishing a correlation with the reversible/irreversible processes detected during the electrochemical lithium insertion

Two new hoards and several solitary finds of metal items of the Bronze Age - Early Hallstatt periods in the territory of Republic of Moldova

Directory of Open Access Journals (Sweden)

Stanislav Ţerna

2013-12-01

Full Text Available The article publishes two new hoards and several solitary finds of bronze items from the Prut-Dniester interfluve. These finds can be dated the late Bronze Age and Early Hallstatt periods and relate to the Sabatinovka and Noua cultures, as well as to different early Hallstatt groups. Of special interest is the hoard from Brăneşti containing some types of items which until now were not known on the territories to the west from the Dniester. Also, remarkable is the structure of these two hoards, which may indicate a votive character of their deposition.

Evaluation of copper, aluminum bronze, and copper-nickel container material for the Yucca mountain project

International Nuclear Information System (INIS)

Kass, J.

1990-01-01

Copper, 70 percent aluminum bronze, and 70/30 copper-nickel were evaluated as potential waste-packaging materials as part of the Yucca Mountain Project. The proposed waste repository site is under a desert mountain in southern Nevada. The expected temperatures at the container surface are higher than at other sites, about 250C at the beginning of the containment period; they could fall below the boiling point of water during this period, but will be exposed to very little water, probably less than 5 l/a. Initial gamma flux will be 10 4 rad/h, and no significant hydrostatic or lithostatic pressure is expected. Packages will contain PWR or BWR fuel, or processed-glass waste. Three copper alloys are being considered for containers: oxygen-free copper (CDA 102); 7 percent aluminum bronze (CDA 613); and 70/30 copper-nickel (CDA 715). Phase separation due to prolonged thermal exposure could be a problem for the two alloys, causing embrittlement. The reduction of internal oxides present in pure copper by hydrogen could cause mechanical degradation. Corrosion and oxidation rates measured for the three materials in well water with and without gamma irradiation at flux rates about ten times higher than those expected were all quite small. The corrosion/oxidation rates for CDA715 show a marked increase under irradiation, but are still acceptable. In the presence of ammonia and other nitrogen-bearing species stress corrosion cracking (SCC) is a concern. Welded U-bend specimens of all three materials have been tested for up to 10000 h in highly irradiated environments, showing no SCC. There was some alloy segregation in the Al bronze specimens. The investigators believe that corrosion and mechanical properties will not present problems for these materials at this site. Further work is needed in the areas of weld inspection, welding techniques, embrittlement of weld metal, the effects of dropping the containers during emplacement, and stress corrosion cracking. Other materials

Variety in cereal cultivation in the Late Bronze and Early Iron Ages in relation to environmental conditions

Czech Academy of Sciences Publication Activity Database

Dreslerová, Dagmar; Kočár, Petr; Chuman, T.; Šefrna, L.; Poništiak, Š.

2013-01-01

Roč. 40, č. 4 (2013), s. 1988-2000 ISSN 0305-4403 Institutional research plan: CEZ:AV0Z80020508 Institutional support: RVO:67985912 Keywords : crop husbandry * charred cereal grains * environment * weather * soil s * Late Bronze Age/Early Iron Age Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 2.139, year: 2013

Bronze age cosmology and rock art images. Solar ships, deer and charts

Science.gov (United States)

Dimitriadis, G.

Bronze Age societies were technologically complex. The impressive production of metal artefacts embodies clearly their astronomical culture and cosmological viewpoint. Same ascertainment is valid also for rock art. In fact, around the European landscape were discovered several cliffs engraved with solar ships, deer and charts. How one could be interpret them? Which is the hidden mentality? From the end of 3rd millennium-early 2nd millennium B. C. deep technological transformations are made by metals. New inventions such metal extraction for weapon production, horse pulling chariot used for war and the bull pulling one used for trade may shorten the culture and material distances between Central Europe and South Mediterranean area. Indeed, taphonomic studies indicate a specific modification of the human body mortuary traditional disposition (orientated to significant astronomical targets) below a substantial transformation of mortuary apparatus with spot evidence of weapons (halberds, swords, knifes) and ornaments (double spiral, lunar shape pectorals). The famous Trundhold Solar chart, the 2nd millennium terracotta chart form Dupljaja, the solar boats petroglyph in Bohusland and the horse rider carved on Philippi's cliffs were conceived by the same mentality: communion with the divinity. Culture expressions as communicate manifestation attested in rock art were produced by the same mentality presented in Bronze Age art-crafts such as, 1. Culture epidemiologic patterns dispersion took place through out iconographic motives, and, 2. Animals can play a double face function inside an analogical-mythological system: a. animal-reflex; b. animal-agent. The question is: Could such petroglyphs help us to "read" archaeoastronomical properly in an archaeological site?

Provenance Studies on Metal Artefacts of the Early Danish Bronze Age: Comparing lead isotope data with the archaeological evidence

DEFF Research Database (Denmark)

Nørgaard, Heide Wrobel; Vandkilde, Helle; Pernicka, Ernst

2017-01-01

As early as 2100 BCE, societies in the hotspot zone of Denmark and Scania began to use metal. However, this region has not exploited metal ores of their own; therefore the origin of the metal used is of key significance to understanding and modelling the cross-European interconnectivities that were...... established through the necessity of trading. The Nordic region was for the very first time fully dependent on one crucial exogenous resource. The related change within the political economy surely resulted in the establishment of the Nordic Bronze Age. However, little is known about the significance......, the extent and the direction of this metal trade. For the Bronze Age in northern Europe (NBA) two possible transport routes stand opposite each other; on the one hand a continental route that connected the Alps, Central Europe and the NBA; and on the other hand, a maritime route linking Mediterranean...

The Influence of Heat Treatment and Quencing Media at Bronze 80% Cu–20% Sn toward Fatique Life

Directory of Open Access Journals (Sweden)

Anak Agung Istri Agung Sri Komaladewi

2012-11-01

Full Text Available Production of the Balinese gamelan product rest on molding process which then continued with forging process, adjustment,and finally the finishing process. But still often to make the failure from this material like. The material become brokebecause heavy thing with the user processing (playing gambelan with continuity in the long time. The broke that happenfrom the heavy thing by the continuety that is called fatigue. At this examination the things that will be up is how much theheat treatment influence and the cooler thing with the fatigue life through the Reversed Bending process. By to variated theheat treatment and cooler thing to Bronze mixture 80%Cu and 20%Sn. This examination to aim at knowing the heattreatment influence and cooler thing at the composition of Bronze 80%Cu and 20%Sn about the fatigue life.The makingprocess of this things made by copper solution and the white Tin with the composition are 80%Cu and 20%Sn by variatedheat treatment and cooler media. The produce of this solution will print with the Reversed Bending speciment. Then thespeciment gift the heat treatment about 6500 C, 7000 C till 7500 C, and then the speciment keep cold by the water, oil and theair. The thing will be analize from the breach counture, Macro Structure and Micro Structure.The examination produceshowing the growing up at the fatigue life in the Bronze mixture 80%Cu - 20%Sn, From the heat treatment 6500 C, 7000 Cand 7500 C and become the drop age fatigue with the water cooler media with the age fatigue abaut 36621 cycle, and thefatigue by oil about 44975 cycle and the air cooler age fatigue about 55191 cycle. The inspection makro structure thebreach face colouring litle bit dark and the inspection mikro structure, the metal structure lool more bright.

Ancient DNA reveals traces of Iberian Neolithic and Bronze Age lineages in modern Iberian horses

DEFF Research Database (Denmark)

Lira, Jaime; Linderholm, Anna; Olaria, Carmen

2010-01-01

Iberian horses supports this suggestion. To test this hypothesis, we analysed mitochondrial DNA from 22 ancient Iberian horse remains belonging to the Neolithic, the Bronze Age and the Middle Ages, against previously published sequences. Only the medieval Iberian sequence appeared in the D1 group...... wild mares during an early Iberian domestication or restocking event, whereas the D1 group probably was introduced into Iberia in later historical times....

Crystal structure and properties of tetragonal EuAg4In8 grown by metal flux technique

International Nuclear Information System (INIS)

Subbarao, Udumula; Sarkar, Sumanta; Peter, Sebastian C.

2015-01-01

The compound EuAg 4 In 8 has been obtained as single crystals in high yield from reactions run in liquid indium. X-ray diffraction on single crystals suggests that EuAg 4 In 8 crystallizes in the CeMn 4 Al 8 structure type, tetragonal space group I4/mmm with lattice constants a=b=9.7937(2) Å and c=5.7492(2) Å. Crystal structure of EuAg 4 In 8 is composed of pseudo Frank–Kasper cages occupied by one europium atom in each ring, which are shared through the corner along the ab plane resulting in a three dimensional network. The magnetic susceptibility of EuAg 4 In 8 was measured in the temperature range 2–300 K, which obeyed Curie–Weiss law above 50 K. Magnetic moment value calculated from the fitting indicates the presence of divalent europium, which was confirmed by X-ray absorption near edge spectroscopy. Electrical resistivity measurements suggest that EuAg 4 In 8 is metallic in nature with a probable Fermi liquid behavior at low temperature. - Graphical abstract: The tetragonal EuAg 4 In 8 has been grown as single crystals from reactions run in liquid indium. Magnetic and XANES measurements suggest divalent nature of Eu and resistivity measurements suggest metallic nature. - Highlights: • EuAg 4 In 8 phase having tetragonal phase is grown by metal flux technique. • Magnetic and XANES measurements exhibit divalent nature of Eu in EuAg 4 In 8 . • Resistivity measurement suggests metallic nature and probable Fermi liquid behavior

Monumental megalithic burial and rock art tell a new story about the Levant Intermediate Bronze “Dark Ages”

Science.gov (United States)

Barash, Alon; Eisenberg-Degen, Davida; Grosman, Leore; Oron, Maya; Berger, Uri

2017-01-01

The Intermediate Bronze Age (IB) in the Southern Levant (ca. 2350–2000 BCE) is known as the “Dark Ages,” following the collapse of Early Bronze urban society and predating the establishment of the Middle Bronze cities. The absence of significant settlements and monumental building has led to the reconstruction of IB social organization as that of nomadic, tribal society inhabiting rural villages with no central governmental system. Excavation in the Shamir Dolmen Field (comprising over 400 dolmens) on the western foothills of the Golan Heights was carried out following the discovery of rock art engravings on the ceiling of the central chamber inside one of the largest dolmens ever recorded in the Levant. Excavation of this multi-chambered dolmen, covered by a basalt capstone weighing some 50 tons, revealed a secondary multi-burial (of both adults and children) rarely described in a dolmen context in the Golan. Engraved into the rock ceiling above the multi-burial is a panel of 14 forms composed of a vertical line and downturned arc motif. 3D-scanning by structured-light technology was used to sharpen the forms and revealed the technique employed to create them. Building of the Shamir dolmens required a tremendous amount of labor, architectural mastery, and complex socio-economic organization well beyond the capacity of small, rural nomadic groups. The monumental megalithic burial of the Shamir dolmens indicates a hierarchical, complex, non-urban governmental system. This new evidence supports a growing body of recent criticism stemming from new discoveries and approaches that calls for rethinking our views of the Levantine IB “Dark Ages.” PMID:28253312

Neutron activation analysis of Lerna ceramics (Greece) at Early Bronze Age: local production and trade exchanges

International Nuclear Information System (INIS)

Attas, M.

1980-01-01

Neutron activation analysis is a powerful tool for determining the provenance of ancient ceramics. A sophisticated analytical system for gamma-ray spectrometry, designed specifically for the chemical analysis of ceramics by thermal neutron activation, was used to determine the concentrations of twenty elements in samples of ancient pottery. The measurements were made relative to the standard pottery of Perlman and Asaro. The purpose of the work was to study the production of fine pottery at the settlement of Lerna, in the Argolid of Greece, during the Early Bronze Age (third millennium BC). About half of the 50 samples analysed formed the major compositional group, which was attributed to Lerna. It included, besides the majority of the samples from the second phase of the Early Bronze Age (Lerna III), several samples from the third phase (Lerna IV); that is, from levels immediately succeeding the great destruction which marks the end of the Lerna III settlement. A small number of objects forms a second group of local origin and includes 4 of the 5 clay sealings sampled. Among the archaeologically unusual objects, several could be attributed to Lerna, while others were characterized as imports [fr

Analyzing Lead Content in Ancient Bronze Coins by Flame Atomic Absorption Spectroscopy: An Archaeometry Laboratory with Nonscience Majors

Science.gov (United States)

Donais, Mary Kate; Whissel, Greg; Dumas, Ashley; Golden, Kathleen

2009-01-01

A unique, interdisciplinary collaboration between chemistry and classics has led to the development of an experiment for nonscience majors. This instrumental analysis experiment was designed for use in an archaeology course to quantify the amount of lead in ancient bronze coins. The coins were corroded beyond visual identification, so provenance…

Atomic Origins of Monoclinic-Tetragonal (Rutile) Phase Transition in Doped VO2 Nanowires.

Science.gov (United States)

Asayesh-Ardakani, Hasti; Nie, Anmin; Marley, Peter M; Zhu, Yihan; Phillips, Patrick J; Singh, Sujay; Mashayek, Farzad; Sambandamurthy, Ganapathy; Low, Ke-Bin; Klie, Robert F; Banerjee, Sarbajit; Odegard, Gregory M; Shahbazian-Yassar, Reza

2015-11-11

There has been long-standing interest in tuning the metal-insulator phase transition in vanadium dioxide (VO2) via the addition of chemical dopants. However, the underlying mechanisms by which doping elements regulate the phase transition in VO2 are poorly understood. Taking advantage of aberration-corrected scanning transmission electron microscopy, we reveal the atomistic origins by which tungsten (W) dopants influence the phase transition in single crystalline WxV1-xO2 nanowires. Our atomically resolved strain maps clearly show the localized strain normal to the (122̅) lattice planes of the low W-doped monoclinic structure (insulator). These strain maps demonstrate how anisotropic localized stress created by dopants in the monoclinic structure accelerates the phase transition and lead to relaxation of structure in tetragonal form. In contrast, the strain distribution in the high W-doped VO2 structure is relatively uniform as a result of transition to tetragonal (metallic) phase. The directional strain gradients are furthermore corroborated by density functional theory calculations that show the energetic consequences of distortions to the local structure. These findings pave the roadmap for lattice-stress engineering of the MIT behavior in strongly correlated materials for specific applications such as ultrafast electronic switches and electro-optical sensors.

Is there an ordered tetragonal phase in the Ti3Al-Nb system?

International Nuclear Information System (INIS)

Banerjee, D.

1994-01-01

In a recent series of papers, describing aging transformations in plasma sprayed Ti-24Al-11Nb, Hsiung and co-workers proposed a new ordered tetragonal structure as the first metastable phase to form in a series of transformations from quenched-in B2 to the equilibrium phase. They describe this new phase as a ''DO 3 like tetragonal structure'' with a composition Ti 5 Al 2 Nb, and lattice parameters, a = 0.65 nm and c/a ≅ 1.02. Their unit cell is constituted by 8 bcc unit cells, and the atomic coordinates of their structure are given in Table 1 on this basis. The symmetry of this structure is P4/mm. Though it is not the smallest possible unit cell for the structure, comparison with other bcc binary derivative structures is easily possible on this basis. The atomic coordinates for the latter, for a ternary composition Ti 2 AlNb, are also given. They note that the site occupation for the Hsiung et al. structure is quite distinct from that for a ternary DO 3 phase or any of the other possible bcc derivative structures (neglecting 2 possibilities with 128 or 432 atoms per unit cell(8) and interstitial ordering)

Charge Density Waves and the Hidden Nesting of Purple Bronze KMo6O17

Science.gov (United States)

Su, Lei; Pereira, Vitor

The layered purple bronze KMo6O17, with its robust triple CDW phase up to high temperatures, became the emblematic example of the ''hidden nesting'' concept. Recent experiments suggest that, on the surface layers, its CDW phase can be stabilized at much higher temperatures, and with a tenfold increase in the electronic gap in comparison with the bulk. Despite such interesting fermiology and properties, the K and Na purple bronzes remain largely unexplored systems, most particularly so at the theoretical level. We introduce the first multi-orbital effective tight-binding model to describe the effect of electron-electron interactions in this system. Upon fixing all the effective hopping parameters in the normal state against an ab-initio band structure, and with only the overall scale of the interactions as sole adjustable parameter, we find that a self-consistent Hartree-Fock solution reproduces extremely well the experimental behavior of the charge density wave (CDW) order parameter in the full range 0 < T < Tc , as well as the precise reciprocal space locations of the partial gap opening and Fermi arc development. The interaction strengths extracted from fitting to the experimental CDW gap are consistent with those derived from an independent Stoner-type analysis This work was supported by the Singapore National Research Foundation under Grant NRF-CRP6-2010-05.

Endogenous Retroviral Insertions Indicate a Secondary Introduction of Domestic Sheep Lineages to the Caucasus and Central Asia between the Bronze and Iron Age

Science.gov (United States)

Schroeder, Oskar; Benecke, Norbert; Frölich, Kai; Peng, Zuogang; Kaniuth, Kai; Sverchkov, Leonid; Reinhold, Sabine; Belinskiy, Andrey; Ludwig, Arne

2017-01-01

Sheep were one of the first livestock species domesticated by humans. After initial domestication in the Middle East they were spread across Eurasia. The modern distribution of endogenous Jaagsiekte sheep retrovirus insertions in domestic sheep breeds suggests that over the course of millennia, successive introductions of improved lineages and selection for wool quality occurred in the Mediterranean region and most of Asia. Here we present a novel ancient DNA approach using data of endogenous retroviral insertions in Bronze and Iron Age domestic sheep from the Caucasus and Pamir mountain areas. Our findings support a secondary introduction of wool sheep from the Middle East between the Late Bronze Age and Iron Age into most areas of Eurasia. PMID:28632161

Endogenous Retroviral Insertions Indicate a Secondary Introduction of Domestic Sheep Lineages to the Caucasus and Central Asia between the Bronze and Iron Age

Directory of Open Access Journals (Sweden)

Oskar Schroeder

2017-06-01

Full Text Available Sheep were one of the first livestock species domesticated by humans. After initial domestication in the Middle East they were spread across Eurasia. The modern distribution of endogenous Jaagsiekte sheep retrovirus insertions in domestic sheep breeds suggests that over the course of millennia, successive introductions of improved lineages and selection for wool quality occurred in the Mediterranean region and most of Asia. Here we present a novel ancient DNA approach using data of endogenous retroviral insertions in Bronze and Iron Age domestic sheep from the Caucasus and Pamir mountain areas. Our findings support a secondary introduction of wool sheep from the Middle East between the Late Bronze Age and Iron Age into most areas of Eurasia.

Crystal structure relation between tetragonal and orthorhombic CsAlD{sub 4}: DFT and time-of-flight neutron powder diffraction studies

Energy Technology Data Exchange (ETDEWEB)

Bernert, Thomas; Krech, Daniel; Felderhoff, Michael; Weidenthaler, Claudia [Department of Heterogeneous Catalysis, Max-Planck-Institut fuer Kohlenforschung, Muelheim/Ruhr (Germany); Kockelmann, Winfried [Rutherford Appleton Laboratory, Harwell Oxford, Didcot (United Kingdom); Frankcombe, Terry J. [Research School of Chemistry, The Australian National University, Canberra, ACT (Australia); School of Physical, Environmental and Mathematic Sciences, The University of New South Wales, Canberra, ACT (Australia)

2015-11-15

The crystal structures of orthorhombic and tetragonal CsAlD{sub 4} were refined from time-of-flight neutron powder diffraction data starting from atomic positions predicted from DFT calculations. The earlier proposed crystal structure of orthorhombic CsAlH{sub 4} is confirmed. For tetragonal CsAlH{sub 4}, DFT calculations predicted a crystal structure in I4{sub 1}/amd as potential minimum structure, while from neutron diffraction studies of CsAlD{sub 4} best refinement is obtained for a disordered structure in the space group I4{sub 1}/a, with a = 5.67231(9) Aa, c = 14.2823(5) Aa. While the caesium atoms are located on the Wyckoff position 4b and aluminium at Wyckoff position 4a, there are two distinct deuterium positions at the Wyckoff position 16f with occupancies of 50 % each. From this structure, the previously reported phase transition between the orthorhombic and tetragonal polymorphs could be explained. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Significance of internal stresses for the martensitic transformation in yttria-stabilized tetragonal zirconia polycrystals during degradation

International Nuclear Information System (INIS)

Schmauder, S.; Schubert, H.

1986-01-01

Various aspects of the tetragonal (t) to monoclinic (m) transformation during degradation have been studied experimentally and theoretically in yttria-stabilized tetragonal zirconia polycrystals (Y-TZP), i.e., polycrystalline t-ZrO/sub 2/ containing Y/sub 2/O/sub 3/ in solution. Transmission electron microscopy (TEM) revealed that protruding grains at the surface of Y-TZP specimens do not transform under corrosive conditions (250 0 C, humid atmosphere) even after n annealing time of 168 h.) Eigenstresses due to anistropic thermal expansion in and around protruding and bulk grains have been calculated for Y-TZP containing 2 and 3 mol% Y/sub 2/O/sub 3/. The prominent role of these stresses on subsequent transformation nucleation during degradation is shown to agree qualitatively with an established free energy concept. The lack of complete transformation of m-ZrO/sub 2/ is attributed to characteristics of the nucleation - and growth- controlled transformation process

Oxygen 1s excitation and tetragonal distortion from core-hole effect in BaTiO3

Science.gov (United States)

Bugnet, Matthieu; Radtke, Guillaume; Botton, Gianluigi A.

2013-11-01

The accurate description of the O 1s excitation in BaTiO3 has been elusive so far. In this Rapid Communication, the electronic structure and the high-resolution electron energy-loss near-edge structures of the O K edge in tetragonal BaTiO3 are investigated using first-principles calculations. The results demonstrate a clear correlation between the broadening of the lower energy fine structure and the anisotropic effects induced by the core-hole potential, which are directly related to the structural distortion occurring in tetragonal BaTiO3. Moreover, we show that a significant improvement of the description of higher-lying structures can be obtained when correcting the energy position of the Ba 4f states. This demonstrates that the O 1s spectrum can be a very effective probe of the distortion and changes in the local electronic structure, and be used as a sensitive tool for studying new materials and ferroelectric transitions.

Synthesis, microstructure and mechanical properties of ceria stabilized tetragonal zirconia prepared by spray drying technique

International Nuclear Information System (INIS)

Sharma, S.C.; Gokhale, N.M.; Dayal, Rajiv; Lazl, Ramji

2002-01-01

Ceria stabilized zirconia powders with ceria concentration varying from 6 to 16 mol% were synthesized using spray drying technique. Powders were characterized for their particle size distribution and specific surface area. The dense sintered ceramics fabricated using these powders were characterized for their microstructure, crystallite size and phase composition. The flexural strength, fracture toughness and micro-hardness of sintered ceramics were measured. High fracture toughness and flexural strength were obtained for sintered bodies with 12 mol% of CeO 2 . Flexural strength and fracture toughness were dependent on CeO 2 concentration, crystallite size and phase composition of sintered bodies. Correlation of data has indicated that the transformable tetragonal phase is the key factor in controlling the fracture toughness and strength of ceramics. It has been demonstrated that the synthesis method is effective to prepare nanocrystalline tetragonal ceria stabilized zirconia powders with improved mechanical properties. Ce-ZrO 2 with 20 wt% alumina was also prepared with flexural strength, 1200 MPa and fracture toughness 9.2 MPa√m. (author)

Formation Mechanism and Dispersion of Pseudo-Tetragonal BaTiO3-PVP Nanoparticles from Different Titanium Precursors: TiCl4 and TiO2

Directory of Open Access Journals (Sweden)

Jinhui Li

2017-12-01

Full Text Available Nano-sized tetragonal BaTiO3 (BT particles that are well dispersed in solution are essential for the dielectric layer in multilayer ceramic capacitor technology. A hydrothermal process using TiCl4 and BaCl2, as source of Ti and Ba, respectively, or the precursor TiO2 as seed for the formation of BT, and poly(vinylpyrrolidone (PVP as a surfactant, was employed in this study to enhance both the dispersibility and tetragonality (c/a simultaneously in a single reaction process. The process parameters, i.e., the ratio of TiO2 substitution of TiCl4, the reaction time, and PVP content were systematically studied, and the growth mechanism and relation between the tetragonality and the particle size are discussed. Dynamic light scattering (DLS analysis was used to show that truncated pseudo-tetragonal BT-PVP particles with an average size of 100 nm, having a narrow size distribution and a coefficient of variation (CV as low as 20% and being mono-dispersed in water, were produced. The narrow particle size distribution is attributed to the ability of PVP to inhibit the growth of BT particles, and the high c/a of BT-PVP to heterogeneous particle growth using TiO2 seeds.

Raman spectroscopy study of the tetragonal-to-monoclinic transition in zirconium oxide scales and determination of overall oxygen diffusion by nuclear microanalysis of O18

International Nuclear Information System (INIS)

Godlewski, J.; Lambertin, M.; Gros, J.P.; Wadier, J.F.; Weidinger, H.

1991-01-01

This paper reports on two allotropic forms of zirconium oxide, monoclinic and tetragonal that have been identified in the scales formed on zirconium alloys. The transition from tetragonal to monoclinic has been followed by Z-ray measurements and Raman laser spectroscopy. Information on the average content of the tetragonal phase was obtained by X-ray diffraction, whereas Raman laser analyses on tapered sections revealed its distribution through the scale thickness. Oxidation exposures were made in an autoclave, using H 2 O 18 and D 2 O 18 to determine the overall diffusion coefficients. In particular, oxide scales have been studied on Zircaloy-4 with three different precipitate sizes, and on a Zr-1Nb alloy, after exposure in an autoclave for between 3 and 100 days. The specimens were analyzed in detail in the vicinity of the kinetics transition point, where the acceleration of corrosion occurs. Raman spectroscopy analyses enabled the crystallographic nature of the ZrO 2 to be determined. Close to the interface, the tetragonal phase content is about 40%, when after the transition the tetragonal phase is transformed into monoclinic. The O 18 diffusion treatment was carried out in an autoclave at 400 degrees C under pressure on specimens previously oxidized for between 3 and 100 days in natural water vapor pressure. The diffusion profiles were determined by nuclear microanalysis using the O 18 (p, α) → N 15 reaction. Based on these profiles, the volume and grain boundary diffusion coefficients were calculated for each material and for each oxidation time

Acoustic emission characterization of the tetragonal-monoclinic phase transformation in zirconia

International Nuclear Information System (INIS)

Clarke, D.R.; Arora, A.

1983-01-01

The processes accompanying the tetragonal-monoclinic phase transformation in zirconia (ZrO 2 ) have been studied using acoustic emission and electron microscopy in an attempt to characterize the different mechanisms by which the transformation can be accommodated in bulk materials. Experiments in which the acoustic emission is detected as specimens are cooled through the transformation, following densification by sintering, are described. For comparison, the acoustic emission from free, nominally unconstrained powders similarly cooled through the transformation is reported. The existence of distinct processes accompanying the phase transformation is established on the basis of postexperiment multiparametric correlation analysis of the acoustic emission

Shape memory lifetime of CeO2-stabilized tetragonal zirconia polycrystals

International Nuclear Information System (INIS)

Zhe Xiaoli; Li Bo; Meng Man

1993-01-01

Lifetime of shape memory effect (SME) of CeO 2 -stabilized tetragonal zirconia polycrystals was studied by means of both tests of constraint stress and constraint strain mode during reverse martensite transformation. Up to 8th cycling of SME, the shape of sample entirely recovered except microcracks in the constraint stress mode and the accumulated strain reached 4.6% in the constraint strain mode. It was found that the yield stress decreased, however, the reverse transformation temperature of stress-induced martensite increased with times of the cycling. The reason of these phenomena are discussed in terms of microcracking and strain energy relaxation

Effect of high energy milling time of the aluminum bronze alloy obtained by powder metallurgy with niobium carbide addition

Energy Technology Data Exchange (ETDEWEB)

Dias, Alexandre Nogueira Ottoboni; Silva, Aline da; Rodrigues, Carlos Alberto; Melo, Mirian de Lourdes Noronha Motta; Rodrigues, Geovani; Silva, Gilbert, E-mail: aottoboni@yahoo.com.br [Universidade Federal de Itajuba (UNIFEI), Itajuba, MG (Brazil)

2017-05-15

The aluminum bronze alloy is part of a class of highly reliable materials due to high mechanical strength and corrosion resistance being used in the aerospace and shipbuilding industry. It's machined to produce parts and after its use cycle, it's discarded, but third process is considered expensive and besides not being correct for environment reasons. Thus, reusing this material through the powder metallurgy (PM) route is considered advantageous. The aluminum bronze chips were submitted to high energy ball milling process with 3% of niobium carbide (NbC) addition. The NbC is a metal-ceramic composite with a ductile-brittle behaviour. It was analyzed the morphology of powders by scanning electron microscopy as well as particle size it was determined. X ray diffraction identified the phases and the influence of milling time in the diffractogram patterns. Results indicates that milling time and NbC addition improves the milling efficiency significantly and being possible to obtain nanoparticles. (author)

3D scanning and printing as conversation tools: an innovative treatment of a vandalized bronze statue, The Thinker by Rodin

NARCIS (Netherlands)

Beentjes, T.; van der Molen, R.; Saunders, D.; Strlic, M.; Korenberg, C.; Luxford, N.; Birkhölzer, K.

2013-01-01

This contribution discusses the innovative treatment of a severely vandalized bronze sculpture, The Thinker by Auguste Rodin, from the Singer Museum in Laren, The Netherlands. Additional aspects of this controversial treatment such as decision making and documentation are also discussed. In 2007 the

Oxidation of zirconium alloys in steam: influence of tetragonal zirconia on oxide growth mechanism

International Nuclear Information System (INIS)

Godlewski, J.

1990-07-01

The oxidation of zirconium alloys in presence of steam, presents after a 'parabolic' growth law, an acceleration of the oxidation velocity. This phenomenon limits the use of zirconium alloys as nuclear fuel cladding element. In order to determine the physico-chemical process leading to this kinetic transition, two approaches have been carried out: the first one has consisted to determine the composition of the oxide layer and its evolution with the oxidation time; and the second one to determine the oxygen diffusion coefficients in the oxide layers of pre- and post-transition as well as their evolution with the oxidation time. The composition of the oxide layers has been determined by two analyses techniques: the X-ray diffraction and the laser Raman spectroscopy. This last method has allowed to confirm the presence of tetragonal zirconium oxide in the oxide layers. Analyses carried out by laser Raman spectroscopy on oxides oblique cuttings have revealed that the tetragonal zirconium oxide is transformed in monoclinic phase during the kinetic transition. A quantitative approach has allowed to corroborate the results obtained by these two techniques. In order to determine the oxygen diffusion coefficients in the oxides layers, two diffusion treatments have been carried out: 1)under low pressure with D 2 18 O 2 ) under high pressure in an autoclave with H 2 18 O. The oxygen 18 concentration profiles have been obtained by two analyses techniques: the nuclear microprobe and the secondary ions emission spectroscopy. The obtained profiles show that the mass transport is made by the volume and particularly by the grain boundaries. The corresponding diffusion coefficients have been calculated with the WHIPPLE and LE CLAIRE solution. The presence of tetragonal zirconium oxide, its relation with the kinetic transition, and the evolution of the diffusion coefficients with the oxidation time, are discussed in terms of internal stresses in the oxide layer and of the oxide layer

The mechanical response of tetragonal zirconia polycrystal to conical indentation

International Nuclear Information System (INIS)

Asif, S.A.S.; Biswas, S.K.

1994-01-01

Blocks of 3Y-TZP were indented with conical diamond indenters. Indentation caused tetragonal to monoclinic phase transformation in a subsurface. Of the cracks generated in the subsurface, radial and lateral cracks can be accounted for by a continuum model of the indented subsurface, built using a combination of the Boussinesq and blister stress fields. Additional ring, median and cone cracks were also observed. It is hypothesized that the latter are motivated by the reduction in blister strength or residual energy brought about by the material damage caused by the phase transformation. This damage reduces the load bearing capacity of the material progressively with increasing normal load. (author). 13 refs., 5 figs., 2 tabs

Agricultural production and stability of settlement systems in Upper Mesopotamia during the Early Bronze Age (third millennium BCE)

Science.gov (United States)

Kalayci, Tuna

This study investigates the relationship between rainfall variation and rain-fed agricultural production in Upper Mesopotamia with a specific focus on Early Bronze Age urban settlements. In return, the variation in production is used to explore stability of urban settlement systems. The organization of the flow of agricultural goods is the key to sustaining the total settlement system. The vulnerability of a settlement system increases due to the increased demand for more output from agricultural lands. This demand is the key for the success of urbanization project. However, without estimating how many foodstuffs were available at the end of a production cycle, further discussions on the forces that shaped and sustained urban settlement systems will be lacking. While large scale fluctuations in the flow of agricultural products between settlements are not the only determinants of hierarchical structures, the total available agricultural yield for each urban settlement in a hierarchy must have influenced settlement relations. As for the methodology, first, Early Bronze Age precipitation levels are estimated by using modern day associations between the eastern Mediterranean coastal areas and the inner regions of Upper Mesopotamia. Next, these levels are integrated into a remote-sensing based biological growth model. Also, a CORONA satellite imagery based archaeological survey is conducted in order to map the Early Bronze Age settlement system in its entirety as well as the ancient markers of agricultural intensification. Finally, ancient agricultural production landscapes are modeled in a GIS. The study takes a critical position towards the traditionally held assumption that large urban settlements (cities) in Upper Mesopotamia were in a state of constant demand for food. The results from this study also suggest that when variations in ancient precipitation levels are translated into the variations in production levels, the impact of climatic aridification on ancient

Mechanism of the monoclinic-to-tetragonal phase transition induced in zirconia and hafnia by swift heavy ions

International Nuclear Information System (INIS)

Benyagoub, Abdenacer

2005-01-01

Recent results demonstrated that defect formation or amorphization are not the only structural changes induced by swift heavy ions in crystalline materials and that under certain circumstances crystalline-to-crystalline phase transitions can also occur. For instance, it was found that both zirconia and hafnia transform from the monoclinic to the tetragonal phase with a kinetics involving a double ion impact process. In order to understand the origin of this ion-beam induced phase transition, the behavior of these twin oxides was analyzed and compared. In fact, the likeness of these materials offered the unique opportunity to impose drastic constraints on the possible models proposed to explain the creation of atomic displacements in the wake of swift heavy ions. This comparison clearly suggests that the thermal spike is the most appropriate process which governs the transition from the monoclinic to the tetragonal phase in zirconia and hafnia

Low Friction in CuO-Doped Yttria-Stabilized Tetragonal Zirconia Ceramics: A Complementary Macro- and Nanotribology Study

NARCIS (Netherlands)

Tocha, E.; Pasaribu, H.R.; Schipper, Dirk J.; Schönherr, Holger; Vancso, Gyula J.

2008-01-01

The tribological behavior of CuO-doped yttria-stabilized tetragonal zirconia (3Y-TZP) ceramics in the absence of additional lubricants was characterized by macroscale pin-on-disk measurements and nanoscale atomic force microscopy (AFM) for a broad range of velocities. The previously observed low

In situ resistance measurements of bronze process Nb-Sn-Cu-Ta multifilamentary composite conductors during reactive diffusion

International Nuclear Information System (INIS)

Tan, K S; Hopkins, S C; Glowacki, B A; Majoros, M; Astill, D

2004-01-01

The conditions under which the Nb 3 Sn intermetallic layer is formed by solid-state reactive diffusion processes in bronze process multifilamentary conductors greatly influence the performance of the conductors. By convention, isothermal heat treatment is used and often causes non-uniformity of A15 layers formed across the wire. Therefore, characterization and optimization of the conductor during the reactive diffusion processes is crucial in order to improve the overall conductor's performance. In this paper, a different characterization approach and perhaps an optimization technique is presented, namely in situ resistance measurement by an alternating current (AC) method. By treating the components of such multifilamentary wires as a set of parallel resistors, the resistances of the components may be combined using the usual rules for resistors in parallel. The results show that the resistivity of the entire wire changes significantly during the reactive diffusion processes. The development of the Nb 3 Sn layer in bronze process Nb-Sn-Cu-Ta multifilamentary wires at different stages of the reactive diffusion processes has been monitored using measured resistivity changes, and correlated with results from DTA, ACS, SEM and EDS

Synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanosized powders prepared using a simple co-precipitation process

Energy Technology Data Exchange (ETDEWEB)

Hsu, Yu-Wei [Graduate Institute of Applied Science, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Yang, Ko-Ho, E-mail: yangkoho@cc.kuas.edu.tw [Graduate Institute of Applied Science, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Department of Mold and Die Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Chang, Kuo-Ming [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Dental Materials Research Center, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Yeh, Sung-Wei [Metal Industries Research and Development Centre, 1001 Kaohsiung Highway, Kaohsiung 811, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100, Shihchuan 1st Road, Kaohsiung 80728, Taiwan (China)

2011-06-16

Highlights: > The thermal behavior of 3Y-TZP precursor powders had been investigated. > The crystallization behavior of 3Y-TZP nanopowders had been investigated. > The activation energy for crystallization of tetragonal ZrO{sub 2} was obtained. > The growth morphology parameter n is approximated as 2.0. > The crystallites show a plate-like morphology. - Abstract: The synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanopowders prepared using a simple co-precipitation process at 348 K and pH = 7 were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), an X-ray diffractometer (XRD), the Raman spectra, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and an energy dispersive spectrometer (EDS). The activation energy of tetragonal ZrO{sub 2} crystallization from 3Y-TZP freeze-dried precursor powders using a non-isothermal method, namely, 169.2 {+-} 21.9 kJ mol{sup -1}, was obtained. The growth morphology parameter n was approximated as 2.0, which indicated that it had a plate-like morphology. The XRD, Raman spectra, and SAED patterns showed that the phase of the tetragonal ZrO{sub 2} was maintained at 1273 K. The crystallite size of 3Y-TZP freeze-dried precursor powders calcined at 1273 K for 5 min was 21.3 nm.

Synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanosized powders prepared using a simple co-precipitation process

International Nuclear Information System (INIS)

Hsu, Yu-Wei; Yang, Ko-Ho; Chang, Kuo-Ming; Yeh, Sung-Wei; Wang, Moo-Chin

2011-01-01

Highlights: → The thermal behavior of 3Y-TZP precursor powders had been investigated. → The crystallization behavior of 3Y-TZP nanopowders had been investigated. → The activation energy for crystallization of tetragonal ZrO 2 was obtained. → The growth morphology parameter n is approximated as 2.0. → The crystallites show a plate-like morphology. - Abstract: The synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanopowders prepared using a simple co-precipitation process at 348 K and pH = 7 were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), an X-ray diffractometer (XRD), the Raman spectra, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and an energy dispersive spectrometer (EDS). The activation energy of tetragonal ZrO 2 crystallization from 3Y-TZP freeze-dried precursor powders using a non-isothermal method, namely, 169.2 ± 21.9 kJ mol -1 , was obtained. The growth morphology parameter n was approximated as 2.0, which indicated that it had a plate-like morphology. The XRD, Raman spectra, and SAED patterns showed that the phase of the tetragonal ZrO 2 was maintained at 1273 K. The crystallite size of 3Y-TZP freeze-dried precursor powders calcined at 1273 K for 5 min was 21.3 nm.

Las Lunas (Yuncler, Toledo. A Bronze Age hoard with metallic materials from the southern Iberian Meseta

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Urbina Martínez, Dionisio

2010-06-01

Full Text Available Here we present the results of the preliminary study carried out on a new group of metallic materials of the Final Bronze Age, recovered at the end of 2008 in the archaeological excavations at the settlement of Las Lunas (Yuncler, Toledo, Spain. Its geographical situation far away from the main zones of distribution of this type of finds, the singularity of the materials, and the evidence of Atlantic and Mediterranean relations make these materials a remarkable sample for the study of the Final Bronze Age in the centre of the Iberian Peninsula.

Se exponen los resultados del primer estudio realizado sobre un nuevo conjunto de materiales metálicos del Bronce Final recuperado a finales de 2008 en las excavaciones arqueológicas del yacimiento de Las Lunas (Yuncler, Toledo, España. La localización geográfica del hallazgo, lejos de las principales zonas de dispersión conocidas para este tipo de conjuntos, la singularidad de los objetos que integra, y las relaciones atlánticas y mediterráneas que evidencian sus materiales, lo convierten en un ejemplo destacado para el estudio de este período en el centro de la Península Ibérica.

Infrared studies of the monoclinic-tetragonal phase transition in Pb(Zr,Ti)O3 ceramics

International Nuclear Information System (INIS)

Guarany, C A; Pelaio, L H Z; Araujo, E B; Yukimitu, K; Moraes, J C S; Eiras, J A

2003-01-01

Recently, the observation of a new monoclinic phase in the PbZr 1-x Ti x O 3 (PZT) system in the vicinity of the morphotropic phase boundary was reported. Investigations of this new phase were reported using different techniques such as high-resolution synchrotron x-ray powder diffraction and Raman spectroscopy. In this work, the monoclinic → tetragonal phase transition in PbZr 0.50 Ti 0.50 O 3 ceramics was studied using infrared spectroscopy between 1000 and 400 cm -1 . The four possible ν 1 -stretching modes (Ti-O and Zr-O stretch) in the BO 6 octahedron in the ABO 3 structure of PZT in this region were monitored as a function of temperature. The lower-frequency mode ν 1 -(Zr-O) remains practically unaltered, while both intermediate ν 1 -(Ti-O) modes decrease linearly as temperature increases from 89 to 263 K. In contrast, the higher-frequency ν 1 -(Ti-O) and ν 1 -(Zr-O) modes present anomalous behaviour around 178 K. The singularity observed at this mode was associated with the monoclinic → tetragonal phase transition in PbZr 0.50 Ti 0.50 O 3 ceramics

Preliminary Assessment about Genetic Diversity, the Stability of Potential Mutants from Two Varieties of Chrysanthemum morifolium Ramat. (Bronze Doa and Purple Farm) via Gamma Irradiation

International Nuclear Information System (INIS)

Nguyen Tuong Mien; Le Ngoc Trieu; Le Tien Thanh; Pham Van Nhi; Huynh Thi Trung

2013-01-01

The aim of this study was to evidence the efficiency of irradiation by gamma ray from 60 Co source on chrysanthemum artificial seeds, through that select a number of potential mutants from two varieties of Chrysanthemum morifolium Ramat artificial seeds (Bronze and purple chrysanthemum). The experimental result showed that LD 50 for the Bronze Doa variety was 50 Gy and Purple Farm variety was 100 Gy. Irradiated in vitro artificial seeds were transferred into fresh MS medium and placed in the growth room with three replications at each of dose. The completed in vitro plants were transplanted into ex vitro condition in green house. After 30 days in the greenhouse, survival rate of plantlets were and growth in 20 Gy and 40 Gy for Purple chrysanthemum, while the number of survival Bronze chrysanthemum plantlets were reduced gradually toward the increasing of gamma doses. In this study, on farm, through screening 18 phenotypic mutants of both chrysanthemums were recorded and collected including 6 potential mutants that selected for next research based on their phenotypic differences to the originals, their aesthetic and low mosaic. These 6 potential mutants together with their original varieties were micro-propagated to induce the potential mutant lines for estimation on farm of mutant characteristic segregation rates. (author)

Quantum Mechanical Calculations Of Elastic Properties Of Doped Tetragonal Yttria-Stabilized Zirconium Dioxide

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Yuriy Natanzon

2008-01-01

Full Text Available We report first principles calculations of the electronic and elastic properties of yttriastabilized tetragonal zirconium dioxide doped with metal oxides like: GeO2, TiO2, SiO2,MgO and Al2O3. It is shown that addition of such dopants affects selected elastic propertiesof ZrO2, which is driven by the attraction of electron density by dopant atom and creationof stronger dopant–oxygen bonds. This effect contributes to the increase of superplasticityof doped material.

CeO2-stabilized tetragonal ZrO2 polycrystals (Ce-TZP ceramics)

International Nuclear Information System (INIS)

Andrade Nono, M.C. de.

1990-12-01

This work presents the development and the characterization of CeO 2 -stabilized tetragonal ZrO 2 polycrystals (Ce-TZP ceramics), since it is considered candidate material for applications as structural high performance ceramics. Sintered ceramics were fabricated from mixtures of powders containing different CeO 2 content prepared by conventional and nonconventional techniques. These powders and their resultant sintered ceramics were specified by chemical and physical characterization, compactation state and mechanical properties. The chemical characteristics were determined by chemical analysis and the physical characteristics were evaluated by phase content, particle and agglomerate size and aspect, and powder porosity. (author)

Tetragonal-cubic phase boundary in nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions synthesized by gel-combustion

Energy Technology Data Exchange (ETDEWEB)

Fabregas, Ismael O. [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Craievich, Aldo F.; Fantini, Marcia C.A. [Instituto de Fisica, Universidade de Sao Paulo, Travessa R da Rua do Matao, No. 187, Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Millen, Ricardo P.; Temperini, Marcia L.A. [Instituto de Quimica, Universidade de Sao Paulo, Avenida Prof. Lineu Prestes 748, Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Lamas, Diego G., E-mail: dlamas@uncoma.edu.ar [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Laboratorio de Caracterizacion de Materiales, Facultad de Ingenieria, Universidad Nacional del Comahue, Buenos Aires 1400, (8300) Neuquen Capital, Prov. de Neuquen (Argentina)

2011-04-21

Research highlights: > Gel-combustion synthesis yields compositionally homogeneous, single-phased ZrO{sub 2}-Y{sub 2}O{sub 3} nanopowders, that exhibit the presence at room temperature of three different phases depending on Y{sub 2}O{sub 3} content, namely two tetragonal forms (t' and t'') and the cubic phase. > Phase identification can be achieved by synchrotron XPD (SXPD) and Raman spectroscopy since the tetragonal forms and the cubic phase can be distinguished by these techniques. > The crystallographic features of ZrO{sub 2}-Y{sub 2}O{sub 3} nanopowders were determined by SXPD. They are similar to those reported by Yashima and coworkers for compositionally homogeneous materials containing larger (micro)crystals. However, the lattice parameters are slightly different and the axial ratios c/a of our t' samples are smaller than those reported by these authors. > Compositional t'/t'' and t''/cubic phase boundaries are located at (9 {+-} 1) and (10.5 {+-} 0.5) mol% Y{sub 2}O{sub 3}, respectively. > For the whole series of nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions studied in the present work, no evidences of the presence of a mixture of phases - as reported by Yashima and coworkers for microcrystalline solid solutions - were detected. - Abstract: By means of synchrotron X-ray powder diffraction (SXPD) and Raman spectroscopy, we have detected, in a series of nanocrystalline and compositionally homogeneous ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions, the presence at room temperature of three different phases depending on Y{sub 2}O{sub 3} content, namely two tetragonal forms and the cubic phase. The studied materials, with average crystallite sizes within the range 7-10 nm, were synthesized by a nitrate-citrate gel-combustion process. The crystal structure of these phases was also investigated by SXPD. The results presented here indicate that the studied nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid

Early atmospheric metal pollution provides evidence for Chalcolithic/Bronze Age mining and metallurgy in Southwestern Europe.

Science.gov (United States)

Martínez Cortizas, Antonio; López-Merino, Lourdes; Bindler, Richard; Mighall, Tim; Kylander, Malin E

2016-03-01

Although archaeological research suggests that mining/metallurgy already started in the Chalcolithic (3rd millennium BC), the earliest atmospheric metal pollution in SW Europe has thus far been dated to ~3500-3200 cal.yr. BP in paleo-environmental archives. A low intensity, non-extensive mining/metallurgy and the lack of appropriately located archives may be responsible for this mismatch. We have analysed the older section (>2100 cal.yr. BP) of a peat record from La Molina (Asturias, Spain), a mire located in the proximity (35-100 km) of mines which were exploited in the Chalcolithic/Bronze Age, with the aim of assessing evidence of this early mining/metallurgy. Analyses included the determination of C as a proxy for organic matter content, lithogenic elements (Si, Al, Ti) as markers of mineral matter, and trace metals (Cr, Cu, Zn, Pb) and stable Pb isotopes as tracers of atmospheric metal pollution. From ~8000 to ~4980 cal.yr. BP the Pb composition is similar to that of the underlying sediments (Pb 15 ± 4 μg g(-1); (206)Pb/(207)Pb 1.204 ± 0.002). A sustained period of low (206)Pb/(207)Pb ratios occurred from ~4980 to ~2470 cal.yr. BP, which can be divided into four phases: Chalcolithic (~4980-3700 cal.yr. BP), (206)Pb/(207)Pb ratios decline to 1.175 and Pb/Al ratios increase; Early Bronze Age (~3700-3500 cal.yr. BP), (206)Pb/(207)Pb increase to 1.192 and metal/Al ratios remain stable; Late Bronze Age (~3500-2800 cal.yr. BP), (206)Pb/(207)Pb decline to their lowest values (1.167) while Pb/Al and Zn/Al increase; and Early Iron Age (~2800-2470 cal.yr. BP), (206)Pb/(207)Pb increase to 1.186, most metal/Al ratios decrease but Zn/Al shows a peak. At the beginning of the Late Iron Age, (206)Pb/(207)Pb ratios and metal enrichments show a rapid return to pre-anthropogenic values. These results provide evidence of regional/local atmospheric metal pollution triggered by the earliest phases of mining/metallurgy in the area, and reconcile paleo-environmental and

Critical behavior of the spontaneous polarization and the dielectric susceptibility close to the cubic-tetragonal transition in BaTiO3

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H. Yurtseven

2015-09-01

Full Text Available Using Landau mean field model, the spontaneous polarization and the dielectric susceptibility are analyzed as functions of temperature and pressure close to the cubic–tetragonal (ferroelectric–paraelectric transition in BaTiO3. From the analysis of the dielectric susceptibility and the spontaneous polarization, the critical exponents are deduced in the classical and quantum limits for BaTiO3. From the critical behavior of the dielectric susceptibility, the spontaneous polarization can be described for the ferroelectric–paraelectric (cubic to tetragonal transition between 4 and 8 GPa at constant temperatures of 0 to 200 K in BaTiO3 within the Landau mean field model given here.

Study of patina formation on bronze specimens

International Nuclear Information System (INIS)

Oliveira, F.J.R. de; Lago, D.C.B.; Senna, L.F.; Miranda, L.R.M. de; D'Elia, E.

2009-01-01

In this study, bronze samples (94.059% Cu; 0.023% Zn; 0.077% Pb and 5.801% Sn, w/w) were exposed for 8 months to a marine atmosphere (splash zone) at Barra of Tijuca Beach, Rio de Janeiro. X-ray diffraction analysis (XRD) was used to identify the composition of the corrosion products formed on the samples. The electrochemical properties were analyzed using potential and electrochemical impedance measurements. These analyses and measurements were obtained from periodically removed samples, and compared to those exposed to laboratory tests (total and alternating immersion) in 10 -2 mol L -1 NaCl solution. The corrosion potential results, allied to XRD analysis, showed that the chemical nature of the films obtained on the surface of the field test samples was very similar to that obtained in the alternating immersion test. The main products identified were cuprite and atacamite. However, the film formed during the total immersion (TI) test was primarily composed of cuprite with nantokite traces, which was not observed in either the field or in alternating tests. The electrochemical impedance measurements obtained in laboratory and field test samples showed the formation of films with a porous structure. The thermodynamic evaluation was also consistent with the corrosion products formed.

Local atomic structure in tetragonal pure ZrO{sub 2} nanopowders

Energy Technology Data Exchange (ETDEWEB)

Acuna, Leandro M.; Lamas, Diego G.; Fuentes, Rodolfo O.; Fabregas, Ismael O. [CITEFA-CONICET, Villa Martelli, Provincia de Buenos Aires (AR). CINSO (Centro de Investigaciones en Solidos); Fantini, Marcia C.A.; Craievich, Aldo F. [Universidade de Sao Paulo (Brazil). Inst. de Fisica; Prado, Rogerio J. [Universidade Federal de Mato Grosso (UFMT), Cuiaba (Brazil). Inst. de Fisica

2010-04-15

The local atomic structures around the Zr atom of pure (undoped) ZrO{sub 2} nanopowders with different average crystallite sizes, ranging from 7 to 40 nm, have been investigated. The nanopowders were synthesized by different wetchemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO{sub 2} nanopowders can be described by a model consisting of two oxygen subshells (4+4 atoms) with different Zr-O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye-Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to the z direction; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4+2+2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments. (orig.)

Accommodation of tin in tetragonal ZrO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Bell, B. D. C.; Grimes, R. W.; Wenman, M. R., E-mail: m.wenman@imperial.ac.uk [Department of Materials and Centre for Nuclear Engineering, Imperial College, London SW7 2AZ (United Kingdom); Murphy, S. T. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Burr, P. A. [Department of Materials and Centre for Nuclear Engineering, Imperial College, London SW7 2AZ (United Kingdom); Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation, Menai, New South Wales 2234 (Australia)

2015-02-28

Atomic scale computer simulations using density functional theory were used to investigate the behaviour of tin in the tetragonal phase oxide layer on Zr-based alloys. The Sn{sub Zr}{sup ×} defect was shown to be dominant across most oxygen partial pressures, with Sn{sub Zr}{sup ″} charge compensated by V{sub O}{sup ••} occurring at partial pressures below 10{sup −31 }atm. Insertion of additional positive charge into the system was shown to significantly increase the critical partial pressure at which Sn{sub Zr}{sup ″} is stable. Recently developed low-Sn nuclear fuel cladding alloys have demonstrated an improved corrosion resistance and a delayed transition compared to Sn-containing alloys, such as Zircaloy-4. The interaction between the positive charge and the tin defect is discussed in the context of alloying additions, such as niobium and their influence on corrosion of cladding alloys.

Necropolis on Bor lake: New reports on Bronze age burial

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Kapuran Aleksandar

2011-01-01

Full Text Available This article deals with the social and anthropological aspects of burial rituals during the Middle Bronze Age in Timočka Krajina. Decades of systematic research of necropolises and reconnaissance in the basin of the Crni Timok proved an increase in number of sites around ore - rich areas of the east Kučaj mountains as well as around Romuliana site and the fertile valleys of Džanovo polje (Map. 1. The quantitative increase in settlements was reflected by the emergence of large necropolises, only three of which have been systematically explored; those in Trnjani, Magura and Bor Lake (Fig. 1; Plan 1. Analysis of geographical features of many settlements and their position in relation to natural resources helped define two communities, one of which carried out mining and metallurgical activities, while the other group engaged in the production of food. Both groups lived in the immediate vicinity and mutual dependence, functioning within a developed market for copper production. During the exploration of the necropolis near Bor Lake in 1997, the remains of burnt skeletons were collected from burial structures 2/97 and 13/97 (Fig. 2; Plans 2 and 3. Anthropological analysis of the cremated remains of the deceased showed that high temperatures were used during the cremation process, which we assume could have only been achieved in metallurgical furnaces. This is confirmed by the fact that the skeletal fragments contain traces of melted metal, as well as finds of bronze slag inside urns and grave structures in the necropolis in Trnjani (Figs. 3 and 4; Tables 1-4. Burial ritual of this kind was not proved by systematic archaeological research of necropolises in the basin of Crni Timok, although anthropological data collected from necropolises linked to metallurgical settlements may indicate some guidelines in the ritual cremation of prominent members of these communities. [Projekat Ministarstva nauke Republike Srbije, br. 177020: Arheologija Srbije

[The early bronze age graveyards of Franzhausen I, lower Austria. 2. Demographic analysis].

Science.gov (United States)

Berner, M

1992-04-01

In a recent study of 714 graves of the Early Bronze Age cemetery, Franzhausen I, 658 individuals were demographically analysed. The masculinity rate and the mortality rate in the age groups were of similar order compared with estimates derived from other series of this period. On the base of a stationary population model, life tables were calculated showing life expectancy at birth to be 25.8 years and at the age of 20, 17.7 years. Also computed were: the crude death rate (Z = 38.8); and the population size (P = 31 or 65). The lack of infants were estimated by regressions (5q0 = 58%) and the results are discussed.

The Influence of Pseudomonas fluorescens on Corrosion Products of Archaeological Tin-Bronze Analogues

Science.gov (United States)

Ghiara, G.; Grande, C.; Ferrando, S.; Piccardo, P.

2018-01-01

In this study, tin-bronze analogues of archaeological objects were investigated in the presence of an aerobic Pseudomonas fluorescens strain in a solution, containing chlorides, sulfates, carbonates and nitrates according to a previous archaeological characterization. Classical fixation protocols were employed in order to verify the attachment capacity of such bacteria. In addition, classical metallurgical analytical techniques were used to detect the effect of bacteria on the formation of uncommon corrosion products in such an environment. Results indicate quite a good attachment capacity of the bacteria to the metallic surface and the formation of the uncommon corrosion products sulfates and sulfides is probably connected to the bacterial metabolism.

Growth kinetics of tetragonal and monoclinic ZrO2 crystallites in 3 mol% yttria partially stabilized ZrO2 (3Y-PSZ) precursor powder

International Nuclear Information System (INIS)

Kuo, Chih-Wei; Lee, Kuen-Chan; Yen, Feng-Lin; Shen, Yun-Hwei; Lee, Huey-Er; Wen, Shaw-Bing; Wang, Moo-Chin; Stack, Margaret Mary

2014-01-01

Highlights: • The crystalline structures were composed of tetragonal and monoclinic ZrO 2 . • Growth kinetics of t-ZrO 2 in the 3Y-PSZ precursor powder is described as: D te 2 =(4.57±0.55)t 0.12±0.02 exp(-((24.79±0.38)×10 3 )/(RT) ). • Growth kinetics of m-ZrO 2 in the 3Y-PSZ precursor powder is described as: D m 2 =(4.40±1.63)t 0.17±0.08 exp(-((66.47±3.97)×10 3 )/(RT) ). - Abstract: The growth kinetics of tetragonal and monoclinic ZrO 2 crystallites in 3 mol% yttria partially stabilized ZrO 2 (3Y-PSZ) precursor powder has been investigated using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) specific surface area analysis, transmission electron microscopy (TEM) and high resolution TEM (HRTEM). After calcination of the 3Y-PSZ precursor powder between 773 and 1073 K for 2 h, the crystalline structures were composed of tetragonal and monoclinic ZrO 2 as the primary and secondary phases, respectively. When the 3Y-PSZ precursor powder was calcined at 773 K for 2 h, the BET specific surface area was 97.13 m 2 /g, which is equivalent to a particle size of 10.30 nm. The crystallite sizes determined via XRD and BET agreed well, indicating that the powder was virtually non-agglomerated. The growth kinetics of tetragonal and monoclinic ZrO 2 crystallite isothermal growth in the 3Y-PSZ precursor powder are described by: D te 2 =(4.57±0.55)t 0.12±0.02 exp(-((24.79±0.38)×10 3 )/(RT) ) and D m 2 =(4.40±1.63)t 0.17±0.08 exp(-((66.47±3.97)×10 3 )/(RT) ), respectively, for 773K≤T≤1073K. D te and D m denote the crystallite size of tetragonal and monoclinic ZrO 2 at time t and temperature T, respectively

Anelastic anomalies and negative Poisson's ratio in tetragonal BaTiO3 ceramics

International Nuclear Information System (INIS)

Dong Liang; Stone, Donald S.; Lakes, Roderic S.

2010-01-01

Anelastic anomalies (sharp variations in modulus and damping with temperature) were observed in tetragonal BaTiO 3 via broadband viscoelastic spectroscopy after aging at 50 deg. C for 15 h. The effect was most pronounced under electrical short circuit condition, at low frequency and under small excitation strain (10 -6 ). Softening in bulk modulus and negative Poisson's ratio were observed near 60 deg. C. Effects are attributed to an oxygen vacancy mechanism. A relaxational model cannot account for sharp response at smaller strains. Heterogeneity of negative stiffness is considered as a cause.

Critical current, electro-mechanical properties and specific heat of bronze Nb{sub 3}Sn conductors

Energy Technology Data Exchange (ETDEWEB)

Uglietti, D.; Seeber, B.; Abacherli, V.; Flukiger, R. [Geneva Univ., Groupe Applique de Physique (GAP) (Switzerland); Wang, X.Y.; Junod, A.; Flukiger, R. [Geneva Univ., Dept. Phys. Mat. Condensee (DPMC) (Switzerland)

2004-07-01

The fabrication process leading to a Nb{sub 3}Sn wire by using the bronze route with 15.4 wt per cent of Sn is described. The critical current density, J{sub c}, is studied as a function of the applied magnetic field, B, up to 25 T; the uniaxial strain, {epsilon}, was measured up to 17. In the second part our device for measuring I{sub c}({epsilon}) is presented. The device is based on the concept of the Walters spring (WASP), which allows to measure long length wires (voltage taps distance up to 50 cm), up to 1000 A and to obtain an absolute measurement of the strain value. It is thus possible to measure the voltage-current relation of technical superconducting wires and tapes down to 0.01 {mu}V/cm, an important requirement for the characterisation in view of applications like NMR high field magnets which require persistent mode operation with high current densities. Finally specific heat measurements on Nb{sub 3}Sn wires prepared at GAP have allowed to determine for the first time the overall distribution of T{sub c} in the filaments. The onset of T{sub c} was observed at 17.2 K, the T{sub c} distribution being centred at 15.9 K. This analysis confirms the reduction of T{sub c} due to the Ti addition and the presence of a distribution of Sn in Nb{sub 3}Sn bronze wires. (authors)

Prehistoric contacts over the Straits of Gibraltar indicated by genetic analysis of Iberian Bronze Age cattle.

Science.gov (United States)

Anderung, Cecilia; Bouwman, Abigail; Persson, Per; Carretero, José Miguel; Ortega, Ana Isabel; Elburg, Rengert; Smith, Colin; Arsuaga, Juan Luis; Ellegren, Hans; Götherström, Anders

2005-06-14

The geographic situation of the Iberian Peninsula makes it a natural link between Europe and North Africa. However, it is a matter of debate to what extent African influences via the Straits Gibraltar have affected Iberia's prehistoric development. Because early African pastoralist communities were dedicated to cattle breeding, a possible means to detect prehistoric African-Iberian contacts might be to analyze the origin of cattle breeds on the Iberian Peninsula. Some contemporary Iberian cattle breeds show a mtDNA haplotype, T1, that is characteristic to African breeds, generally explained as being the result of the Muslim expansion of the 8th century A.D., and of modern imports. To test a possible earlier African influence, we analyzed mtDNA of Bronze Age cattle from the Portalón cave at the Atapuerca site in northern Spain. Although the majority of samples showed the haplotype T3 that dominates among European breeds of today, the T1 haplotype was found in one specimen radiocarbon dated 1800 calibrated years B.C. Accepting T1 as being of African origin, this result indicates prehistoric African-Iberian contacts and lends support to archaeological finds linking early African and Iberian cultures. We also found a wild ox haplotype in the Iberian Bronze Age sample, reflecting local hybridization or backcrossing or that aurochs were hunted by these farming cultures.

Food offerings, flowers, a bronze bucket and a waggon: a multidisciplinary approach regarding the Hallstatt princely grave from Prague-Letňany, Czech Republic

Czech Academy of Sciences Publication Activity Database

Kozáková, Radka; Kyselý, René; Trefný, M.; Drábková, K.; Kočár, Petr; Frolíková, Drahomíra; Kočárová, R.; Moravcová, Kamila

-, - (2017) ISSN 1866-9557 Institutional support: RVO:67985912 Keywords : grave * meat offerings * pollen * bronze bucket * paint * infrared spectroscopy * xylotomic analysis Subject RIV: AC - Archeology, Anthropology, Ethnology OBOR OECD: Archaeology Impact factor: 1.844, year: 2016

Pithouses or ritual dumps? On Late Bronze and Early Iron Age’s material context type in the South of the Iberian Peninsula. The dump of Cortijo Riquelme (Almería

Directory of Open Access Journals (Sweden)

José Luis LÓPEZ CASTRO

2017-12-01

Full Text Available Cortijo Riquelme is a Late Bronze and Early Iron Age’s archaeological dump in the South East of the Iberian Peninsula which belongs to the so called pithouses. This traditional interpretation has been rejected by recent critical studies. Following this positions, the paper analyzes the mentioned dump, which mainly contained Late Bronze and very ancient Phoenician imported pottery, showing the introduction of Phoenician wine and the service for its consumption. A comparison is done with other similar dumps distributed in the South of the Iberian peninsula from Late Bronze Age, though the majority are dated during the early centuries if the 1st millennium bc, coinciding with the Phoenician colonization. Another Mediterranean dumps from Crete, Cyprus, Sicily and North Africa related with feasts help to propose an interpretation for the dump of Cortijo Riquelme and others of the same type, in which the ritual deposit of the containers used in feasts should contribute to the formation of dumps, in a context of increasing competition of local elites in processes of social differentiation.

Sm/Ti co-substituted bismuth ferrite multiferroics: reciprocity between tetragonality and piezoelectricity.

Science.gov (United States)

Jha, Pardeep K; Jha, Priyanka A; Singh, Prabhakar; Ranjan, Rajeev; Dwivedi, R K

2017-10-04

BiFeO 3 (BFO) systems co-modified with Ti, Sm and Sm-Ti have been investigated for piezoelectricity together with dielectric and multiferroic properties. Structural studies revealed the coexistence of orthorhombic and rhombohedral (R3c) phases for x > 0.12. Impurity phases were shown to have hardly any effect on the remanent magnetization, which rather depends on the Fe-O-Fe bond angle. The dielectric loss was reduced considerably by substitution. A correlation between the piezoelectric coefficient and tetragonality was observed in these samples. BFO co-substituted with Sm-Ti exhibited a high piezoelectric coefficient with better ferroic properties, which revealed a unique combination of green piezoelectricity and multiferroicity.

Infant/child burials and social reproduction in the Bronze Age and Early Iron Age (c. 2100-800 BC) of Central Italy

NARCIS (Netherlands)

Rossenberg, E.A.; Bacvarov, K

2008-01-01

Abstract: Special treatment of the remains of children is a well-known feature in Central Italy from the Neolithic onwards. Here I will focus on the evidence for the Bronze Age and Early Iron Age in two adjacent Central Italian regions (Abruzzo and Lazio). It will be argued that mortuary practice

On the effective mass in tetragonal semiconductors in the presence of an arbitrarily oriented quantizing magnetic field

International Nuclear Information System (INIS)

Mondal, M.; Ghatak, K.P.

1984-01-01

A generalized expression of the effective mass of charge carriers in tetragonal semiconductors (taking n-Cd 3 As 2 as an example) in the presence of arbitrary magnetic quantization has been derived considering the generalized dispersion relation of the conduction electrons and taking into account only the effective mass of the electrons at the Fermi surface

Thermodynamic theory of intrinsic finite-size effects in PbTiO3 nanocrystals. I. Nanoparticle size-dependent tetragonal phase stability

Science.gov (United States)

Akdogan, E. K.; Safari, A.

2007-03-01

We propose a phenomenological intrinsic finite-size effect model for single domain, mechanically free, and surface charge compensated ΔG-P ⃗s-ξ space, which describes the decrease in tetragonal phase stability with decreasing ξ rigorously.

Magnetic susceptibility of the rare earth tungsten oxide bronzes of the defected perovskite-type structure (Rsub(x)WO/sub 3/)

Energy Technology Data Exchange (ETDEWEB)

Gesicki, A; Polaczek, A [Warsaw Univ. (Poland)

1975-01-01

Magnetic susceptibility of rare earth tungsten bronzes Rsub(x)WO/sub 3/ of cubic symmetry was measured in the 80-293 K range with the Gouy method. In disagreement with the data reported by other authors it was stated that the Curie-Weiss law with negative Weiss parameter was fulfilled in each case. Possible coupling mechanisms are briefly discussed.

Mass spectrometric investigation of evaporation of lithium-vanadium bronze

International Nuclear Information System (INIS)

Kudin, L.S.; Pogrebnoj, A.M.

1996-01-01

The composition of ionic and neutral components of vapour above lithium-vanadium bronze Li 0.2 VO 2.6 has been studied. It is ascertained that molecules of LiVO 3 and O 2 and Li + ions (2.2±0.2); Li + ·LiVO 3 (2.4±0.3); Li + ·(LiVO 3 ) 2 (2.4±0.9); Li + ·V 2 O 5 (2.3±0.9); Cs + (2.1±0.3); Cs + ·LiVO 3 (2.6±1.0) are basic components of saturated vapour, the values of ionic work functions in eV are given in parentheses. Sublimation enthalpy of lithium metavanadate Δ S H 0 (LiVO 3 , 298 K)=457±30 kJ/mol and its formation enthalpy Δ f H 0 (LiVO 3 , gas, 298 k)=-704±30 kJ/mol. have been defined. Using law 2 of thermodynamics the enthalpies of ion-molecular reactions have been defined. ion formation enthalpies being calculated on their basis. 18 refs., 3 figs., 3 tabs

Late Bronze Age in Alcáçova de Santarém (Portugal

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Arruda, Ana Margarida

2015-06-01

Full Text Available The field work that took place in the restaurant area in Jardim das Portas do Sol (Alcáçova de Santarém recovered well-preserved archaeological layers dated to the Late Bronze Age, lying directly underneath the Iron Age phase. The excavation made it possible to collect an important set of ceramics that incorporate printed and incised decoration, which can be easily decoration related to the Cogotas 1 cultural background. Burnished decorations, with grooves on the inner surface and outer strips, are less common. The formal repertoire does not deviate from what is known about the Late Bronze Age in central and southern Iberian Peninsula. The data allow us to propose a chronology centered in the early 1st millennium BCE for this occupation.Durante los trabajos de campo, realizados en el área del restaurante del Jardim das Portas do Sol, se documentaron, por primera vez en Alcáçova de Santarém, niveles conservados del final de la Edad del Bronce, inmediatamente infrapuestos a los de la Edad del Hierro. Su excavación permitió recoger un conjunto de materiales cerámicos que incorpora varios fragmentos decorados por impresión e incisión, que pueden ser fácilmente relacionados con el universo cultural de Cogotas 1. Las decoraciones bruñidas con surcos en la superficie interna y con franjas al exterior son mucho menos frecuentes. El repertorio formal no difiere del conocido para el Bronce Final del centro y sur de la Península Ibérica. Los datos permiten proponer una cronologia del inicio del 1 milenio a.n.e. (siglo IX para esta ocupación.

V3Si multifilamentary superconductor with high overall Jc

International Nuclear Information System (INIS)

Takeuchi, Takao; Inoue, Kiyoshi; Kosuge, Michio; Iijima, Yasuo; Watanabe, Kazuo

1994-01-01

V 3 Si is one of the A15-type superconducting compounds from which single crystals can be quite easily obtained due to the nature of the equilibrium phase diagram. Thus, the fundamental characteristics of A15 compounds (such as electronic structure and cubic-to-tetragonal structural transformation) have been studied with this compound. V 3 Si is, however, also promising in practical use as an alternative to Nb 3 Sn for high field magnets, since the upper critical field H c2 (4.2 K) is more than 20 T. Although the open-quotes bronze process,close quotes the established commercial process to produce Nb 3 Sn conductors, is also available for V 3 Si, the ternary section of the Cu-V-Si phase diagram indicates two diffusion paths are possible: One from the bronze with low Si content (Si 3 Si, and the other from the bronze with higher Si content to V 3 Si via V 5 Si 3 . The high Si bronze is likely to be advantageous in reducing the bronze volume fraction and hence achieving high overall critical current density J c . This is because the initially formed V 5 Si 3 is eventually converted to V 3 Si as long as the total proportion of V to Si in the composite (overall V/Si molar ratio) is kept around 3. However, long times at high temperatures are necessary for appreciable V 3 Si layer growth, thereby yielding grain growth of V 3 Si and lowering the J c of the V 3 Si compound and the overall J c accordingly. In the present study, in order to improve the overall J c , the authors have realized ∼1μm filament diameter by preparing a double-stacked Cu-8.5at.%Si/V composite. The primary bundle is sheathed with a Ta tube. The Si in the bronze inside the Ta is available only for the diffusion reaction, and the overall V/Si ratios is ∼3

Far infrared and Raman response in tetragonal PZT ceramic films

Energy Technology Data Exchange (ETDEWEB)

Buixaderas, E.; Kadlec, C.; Vanek, P.; Drnovsek, S.; Ursic, H.; Malic, B.

2015-07-01

PbZr{sub 0}.38Ti{sub 0}.62O{sub 3} and PbZr{sub 0}.36Ti{sub 0}.64{sub O}3 thick films deposited by screen printing on (0 0 0 1) single crystal sapphire substrates and prepared at two different sintering temperatures, were studied by Fourier-transform infrared reflectivity, time-domain TH{sub z} transmission spectroscopy and micro-Raman spectroscopy. The dielectric response is discussed using the Lichtenecker model to account for the porosity of the films and to obtain the dense bulk dielectric functions. Results are compared with bulk tetragonal PZT 42/58 ceramics. The dynamic response in the films is dominated by an overdamped lead-based vibration in the TH{sub z} range, as known in PZT, but its evaluated dielectric contribution is affected by the porosity and roughness of the surface. (Author)

Cubic-to-Tetragonal Phase Transitions in Ag-Cu Nano rods

International Nuclear Information System (INIS)

Delogu, F.; Mascia, M.

2012-01-01

Molecular dynamics simulations have been used to investigate the structural behavior of nano rods with square cross section. The nano rods consist of pure Ag and Cu phases or of three Ag and Cu domains in the sequence Ag-Cu-Ag or Cu-Ag-Cu. Ag and Cu domains are separated by coherent interfaces. Depending on the side length and the size of individual domains, Ag and Cu can undergo a transition from the usual face-centered cubic structure to a body-centered tetragonal one. Such transition can involve the whole nano rod, or only the Ag domains. In the latter case, the transition is accompanied by a loss of coherency at the Ag-Cu interfaces, with a consequent release of elastic energy. The observed behaviors are connected with the stresses developed at the nano rod surfaces.

Influence of Ta and Ti Doping on the High Field Performance of (Nb, Ta, Ti)3Sn Multifilamentary Wires based on Osprey Bronze with High Tin Content

International Nuclear Information System (INIS)

Abaecherli, V; Uglietti, D; Lezza, P; Seeber, B; Fluekiger, R; Cantoni, M; Buffat, P-A

2006-01-01

Ta and Ti are the most widely used additions for technical Nb 3 Sn multifilamentary superconductors. These elements are known to influence grain growth, grain morphology and chemical composition in the A15 layer, hence the current carrying properties of the wires over a wide magnetic field range. So far only few studies tried to compare systematically Ta and Ti doped and undoped Nb 3 Sn wires in the frame of the same work, down to a nanometric scale. We present an investigation on several multifilamentary (Nb, Ta, Ti) 3 Sn bronze route wires, fabricated at a laboratory scale, with various amounts of additives. The wires consist of fine filaments embedded in a Cu-Sn or Cu-Sn-Ti Osprey bronze with > 15 wt.% Sn and an external Cu stabilization. Microstructural observations are compared with the results of J c and n values measured up to 21 T at 4.2 and 2.2 K, and for longitudinal strains up to 0.5%. Non-Cu J c values up to 300 Amm -2 and n values up to 50 at 17 T and 4.2 K show clearly that wires with Ti addition to the bronze have a better performance with respect to wires with Ti additions to the filaments

Ancient bronze horse muzzles of the Iberian Peninsula

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Garcés Estallo, Ignasi

2011-12-01

Full Text Available Horse muzzles and Bronze muzzles are unique equestrian tools that have been referred to in scattered accounts throughout history. Nevertheless, the majority of these objects have received short descriptions and an overall study is still missing. The lack of a comprehensive study hinges on the over looked importance of these items and the superficial manner that have characterized their documentation. Both these reasons have limited observations on chronology and archaeological investigation. The recent identification of new unpublished exemplars among the Museums’ collections in Barcelona and Lleida has encouraged the authors of this paper to start a new study dedicated to these objects. Starting from a catalogue inclusive of all muzzles and muzzles currently known in the Iberian Peninsula, an attempt will be made to propose an accurate description, typological classification and, for some of the items, a revision of the decorative scenes that have marked their place in bronze horse muzzle and muzzle chronology. The formal development and the chronological framework here proposed refer to those of the exemplars found in Greece and in Italy. The broadening of the geographical area will allow reconsideration of those social phenomena that have in the past determined the diffusion of elements in horse tack throughout most of the western Peninsula in the Mediterranean.

Los bozales y las muserolas en bronce para caballo constituyen unos excepcionales complementos ecuestres cuyo conocimiento se encuentra disperso en una extensa bibliografía. De muchos ejemplares apenas se ha publicado una breve descripción y nunca hasta el presente han sido objeto de un estudio monográfico, quizás por el desaliento que produce el desconocimiento de su procedencia en unos casos, o la superficial noticia del contexto de aparición en la mayoría de ellos, hecho que ha limitado las consideraciones cronológicas y de asociación. La identificación de nuevos

Comparison of LIBS and {mu}-XRF measurements on bronze alloys for monitoring plasma effects

Energy Technology Data Exchange (ETDEWEB)

Alberghina, M F; Barraco, R; Brai, M; Schillaci, T; Tranchina, L, E-mail: tschillaci@unipa.it [Dipartimento di Fisica e Tecnologie Relative, Universita di Palermo, Viale delle Scienze Ed. 18, 90128 Palermo (Italy)

2011-01-01

The laser-induced breakdown spectroscopy (LIBS) technique is often used as atomic spectroscopic technique for elemental analysis of materials. However, it presents some drawbacks that make an accurate quantitative analysis difficult. Since the plasma properties, such as spatial inhomogeneity and plume stoichiometry strongly depend on the experimental conditions, the measurements are less reproducible. In order to evaluate the measurement fluctuations, we propose to use the more established micro X-Ray fluorescence ({mu}-XRF) technique for validating LIBS data. In particular, the quantitative data, obtained by varying the laser fluence, the shot numbers and the temporal acquisition parameters, were compared with those obtained by {mu}-XRF on laboratory made samples of binary, ternary and quaternary bronze alloys. For LIBS measurements a mobile double pulse laser instrument equipped with an high resolution Echelle type monochromator coupled to an intensified CCD camera was used. {mu}-XRF analyses were performed with a portable instrument that uses a micro collimated X-Ray beam and it is equipped with an high resolution detector. The LIBS results show a strong dependence both on the instrumental set up and the chemical-physical properties of the sample. With our findings we could identify the most suitable parameters to be used in the investigation of the different bronze alloys. The possibility to carry out a quantitative analysis by using the LIBS technique was checked through the comparison with related {mu}-XRF data. In particular in this paper we identified a set of reliable LIBS parameters for the quantitative analysis of copper, tin and zinc. Further analyses will be necessary to reach this goal also for the minor constituents as lead.

Mechanism of the transition from orthorhombic to tetragonal YBa 2Cu 3O 7- x. Investigation of a reversible topotactic reaction in the electron microscope

Science.gov (United States)

Müller, J.-H.; Gruehn, R.

The phase transition from orthorhombic to tetragonal could be observed (in situ) with High-Resolution Transmission Electron Microscopy (HRTEM). In superconducting samples of YBa 2Cu 3O 7- x ( x=0.09) twinned areas were found which changed from orthorhombic to tetragonal symmetry upon electron irradiation parallel to the long c axis. In opposition to annealing experiments the length of the c-axis remained unchanged. The transition was reversible in the high vacuum of the electron microscope. Therefore we surmise that this reaction has no reductive character (no perceptible loss of oxygen). Within the tetragonal structure one can assume a statistical sharing (“disorder”) of oxygen by the metal atoms. The transition could also be explained by a migration of oxygen to the surface. After finishing the irradiation experiment and waiting for several minutes, the oxygen seems to occupy partially ordered positions resulting again in an orthorhombic symmetry. In some cases we could observed transition states of the structural transformation. A schematic model of the mechanism is depicted.

Superior Properties of Energetically Stable La2/3Sr1/3MnO3/Tetragonal BiFeO3 Multiferroic Superlattices

KAUST Repository

Feng, Nan; Mi, Wenbo; Wang, Xiaocha; Cheng, Yingchun; Schwingenschlö gl, Udo

2015-01-01

The superlattice of energetically stable La2/3Sr1/3MnO3 and tetragonal BiFeO3 is investigated by means of density functional theory. The superlattice as a whole exhibits a half-metallic character, as is desired for spintronic devices. The interfacial electronic states and exchange coupling are analyzed in details. We demonstrate that the interfacial O atoms play a key role in controlling the coupling. The higher ferroelectricity of tetragonal BiFeO3 and stronger response to the magnetic moment in La2/3Sr1/3MnO3/BiFeO3 superlattice show a strongly enhanced electric control of the magnetism as compared to the rhombohedral one. Therefore, it is particularly practical interest in the magnetoelectric controlled spintronic devices.

Superior Properties of Energetically Stable La2/3Sr1/3MnO3/Tetragonal BiFeO3 Multiferroic Superlattices

KAUST Repository

Feng, Nan

2015-04-30

The superlattice of energetically stable La2/3Sr1/3MnO3 and tetragonal BiFeO3 is investigated by means of density functional theory. The superlattice as a whole exhibits a half-metallic character, as is desired for spintronic devices. The interfacial electronic states and exchange coupling are analyzed in details. We demonstrate that the interfacial O atoms play a key role in controlling the coupling. The higher ferroelectricity of tetragonal BiFeO3 and stronger response to the magnetic moment in La2/3Sr1/3MnO3/BiFeO3 superlattice show a strongly enhanced electric control of the magnetism as compared to the rhombohedral one. Therefore, it is particularly practical interest in the magnetoelectric controlled spintronic devices.

Early atmospheric metal pollution provides evidence for Chalcolithic/Bronze Age mining and metallurgy in Southwestern Europe

Energy Technology Data Exchange (ETDEWEB)

Martínez Cortizas, Antonio, E-mail: antonio.martinez.cortizas@usc.es [Departamento de Edafoloxía e Química Agrícola, Facultade de Bioloxía, Universidade de Santiago de Compostela, Campus Sur s/n, Santiago de Compostela (Spain); López-Merino, Lourdes, E-mail: lourdes.lopez-merino@brunel.ac.uk [Institute of Environment, Health and Societies, Brunel University London, UB8 3PH Uxbridge (United Kingdom); Bindler, Richard, E-mail: richard.bindler@umu.se [Department of Ecology and Environmental Science, Umeå University, Umeå (Sweden); Mighall, Tim, E-mail: t.mighall@abdn.ac.uk [Department of Geography & Environment, School of Geosciences, University of Aberdeen, Elphinstone Road, Aberdeen AB24 3UF (United Kingdom); Kylander, Malin E., E-mail: malin.kylander@geo.su.se [Department of Geological Sciences and the Bolin Centre for Climate Research, Stockholm University, SE-10691, Stockholm (Sweden)

2016-03-01

Although archaeological research suggests that mining/metallurgy already started in the Chalcolithic (3rd millennium BC), the earliest atmospheric metal pollution in SW Europe has thus far been dated to ~ 3500–3200 cal. yr. BP in paleo-environmental archives. A low intensity, non-extensive mining/metallurgy and the lack of appropriately located archives may be responsible for this mismatch. We have analysed the older section (> 2100 cal. yr. BP) of a peat record from La Molina (Asturias, Spain), a mire located in the proximity (35–100 km) of mines which were exploited in the Chalcolithic/Bronze Age, with the aim of assessing evidence of this early mining/metallurgy. Analyses included the determination of C as a proxy for organic matter content, lithogenic elements (Si, Al, Ti) as markers of mineral matter, and trace metals (Cr, Cu, Zn, Pb) and stable Pb isotopes as tracers of atmospheric metal pollution. From ~ 8000 to ~ 4980 cal. yr. BP the Pb composition is similar to that of the underlying sediments (Pb 15 ± 4 μg g{sup −1}; {sup 206}Pb/{sup 207}Pb 1.204 ± 0.002). A sustained period of low {sup 206}Pb/{sup 207}Pb ratios occurred from ~ 4980 to ~ 2470 cal. yr. BP, which can be divided into four phases: Chalcolithic (~ 4980–3700 cal. yr. BP), {sup 206}Pb/{sup 207}Pb ratios decline to 1.175 and Pb/Al ratios increase; Early Bronze Age (~ 3700–3500 cal. yr. BP), {sup 206}Pb/{sup 207}Pb increase to 1.192 and metal/Al ratios remain stable; Late Bronze Age (~ 3500–2800 cal. yr. BP), {sup 206}Pb/{sup 207}Pb decline to their lowest values (1.167) while Pb/Al and Zn/Al increase; and Early Iron Age (~ 2800–2470 cal. yr. BP), {sup 206}Pb/{sup 207}Pb increase to 1.186, most metal/Al ratios decrease but Zn/Al shows a peak. At the beginning of the Late Iron Age, {sup 206}Pb/{sup 207}Pb ratios and metal enrichments show a rapid return to pre-anthropogenic values. These results provide evidence of regional/local atmospheric metal pollution triggered by the

Textile production in the Bronze Age: an assemblage of splindes or bobbins of yarn from the site of Terlinques (Villena, Alicante

Directory of Open Access Journals (Sweden)

Jover Maestre, Francisco Javier

2001-06-01

Full Text Available The archeological field work on the Bronze Age site of Terlinques (Villena, Alicante has given an exceptional sample of spindles or bobbins of rush fibre of yarn in a room destroyed by a violent fire. A meticulous study of these special objects and their process of analysis and restoration yields new perspectives on knowledge in first stages of textile production during Bronze Age in Eastern Spain.

Los trabajos arqueológicos que se llevan a cabo en el yacimiento de la Edad del Bronce de Terlinques (Villena, Alicante han proporcionado un excepcional conjunto de husos o bobinas de hilo de junco. Éstos se hallaban almacenados en el interior de una habitación destruida por un violento incendio. El detenido estudio de estos singulares objetos y su proceso de análisis y restauración nos permite aproximamos, desde nuevas perspectivas, al conocimiento de la producción textil en las etapas iniciales de la Edad del Bronce en el Levante de la Península Ibérica.

Positron annihilation spectroscopy studies of bronze exposed to sandblasting at different pressure

Science.gov (United States)

Kurdyumov, S.; Siemek, K.; Horodek, P.

2017-11-01

An application of Doppler broadening of annihilation line spectroscopy to samples of beryllium bronze DIN-CuBe2 exposed to sandblasting is presented in performed studies. It is familiar that sandblasting introduces open-volume defects. Samples were sandblasted under different pressure for 1 minute using 110 μm particles of Al2O3. For a non-defected sample the constant value of S-parameter was detected. In the cases of sandblasted samples, S-parameter decreased when the depth enhanced. In our studies the thicknesses of defected zones were determined (it was c.a. 30 μm for a sample blasted under pressure of 1 bar and 110 μm - for 5 bar), and it was also observed that if sandblasting pressure is higher the defected zone is larger.

Deformation bands in ceria-stabilized tetragonal zirconia/alumina. 2: Stress-induced aging at room temperature

International Nuclear Information System (INIS)

Sergo, V.; Clarke, D.R.

1995-01-01

A stress-induced aging phenomenon is observed to occur at room temperature in deformation bands introduced into a 8.5 mol% ceria-stabilized tetragonal zirconia/alumina (Ce-TZP/Al 2 O 3 ) composite by flexural loading. The aging occurs with time after unloading and in laboratory air. Over a period of 100 days, the concentration of monoclinic zirconia within a deformation band increases and, in addition, the wedge-shaped deformation band grows with time. Accompanying these two changes are an increase in the tensile stress in the remaining tetragonal zirconia within the deformation band and a consequential increase in the overall compressive stress within the band. The average value of the monoclinic concentration within the deformation band is found to increase parabolically with time, suggesting the mechanism responsible for the observed aging is diffusion limited. Away from the deformation bands, no aging is observed to occur, suggesting aging is stress dependent. Although a water-vapor-mediated mechanism cannot be ruled out, it is proposed that the observed aging is in fact due to a tensile stress assisted chemical reduction of Ce 4+ to Ce 3+ whose rate is controlled by the indiffusion of oxygen vacancies driven by the tensile stress gradient. It is further proposed that the deformation band grows with time the region ahead of the band is under tension a subject to an enhanced rate of reduction

Domain structures of sodium tungsten bronzes, Na/sub x/WO/sub 3/ (0. 4 < x < 1)

Energy Technology Data Exchange (ETDEWEB)

Atoji, M

1978-01-01

Optical-microscope observations with polarized light have shown that the birefringent, twin-domain structure of sodium tungsten bronzes is exhibited by Na-deficient, epitaxial surface films and hence is not a bulk property as had been suggested elsewhere. The film is translucent, 10/sup -2/ - 10/sup -3/ mm thick or less, and often laminates to a multi-film layer. The domain boundaries are sensitive to lateral stress and, apparently, to minute changes in the substrate structure. These and related properties of the film and the substrate are presented.

Electric field-induced phase transitions and composition-driven nanodomains in rhombohedral-tetragonal potassium-sodium niobate-based ceramics

KAUST Repository

Lv, Xiang

2017-08-07

The mechanisms behind the high piezoelectricity of (K,Na)NbO3-based lead-free ceramics were investigated, including electric field-induced phase transitions and composition-driven nanodomains. The construction of a rhombohedral-tetragonal (R-T) phase boundary, confirmed using several advanced techniques, allowed a large piezoelectric constant (d33) of 450 ± 5 pC/N to be obtained in (1-x)K0.4Na0.6Nb0.945Sb0.055O3-xBi0.5Na0.5(Hf1-ySny)O3 (0 ≤ x ≤ 0.06 and 0 ≤ y ≤ 0.5) ceramics possessing an ultralow ΔUT-R of 7.4 meV. More importantly, the existence of an intermediate phase, i.e., the electric-induced phase (EIP), bridging the rhombohedral R [Ps//(111)] and tetragonal T [Ps//(001)] phases during the polarization rotation was demonstrated. Striped nanodomains (∼40 nm) that easily responded to external stimulation were also observed in the ceramics with an R-T phase. Thus, the enhanced piezoelectric properties originated from EIP and the striped nanodomains.

First principles study of the structural and electronic properties of double perovskite Ba2YTaO6 in cubic and tetragonal phases

International Nuclear Information System (INIS)

Deluque Toro, C.E.; Rodríguez M, Jairo Arbey; Landínez Téllez, D.A.; Moreno Salazar, N.O.; Roa-Rojas, J.

2014-01-01

The Ba 2 YTaO 6 double perovskite presents a transition from cubic (Fm−3m) to tetragonal structure (I4/m) at high temperature. In this work, we present a detailed study of the structural and electronic properties of the double perovskite Ba 2 YTaO 6 in space group Fm−3m and I4/m. Calculations were made with the Full-Potential Linear Augmented Plane Wave method (FP-LAPW) within the framework of the Density Functional Theory (DFT) with exchange and correlation effects in the Generalized Gradient (GGA) and Local Density (LDA) approximations. From the minimization of energy as a function of volume and the fitting of the Murnaghan equation some structural characteristics were determined as, for example, total energy, lattice parameter (a=8.50 Å in cubic phase and a=5.985 Å and c=8.576 Å in tetragonal), bulk modulus (135.6 GPa in cubic phase and 134.1 GPa in tetragonal phase) and its derivative. The study of the electronic characteristics was performed from the analysis of the electronic density of states (DOS). We find a non-metallic behavior for this with a direct band gap of approximately 3.5 eV and we found that the Ba 2 YTaO 6 (I4/m) phase is the most stable one. © 2013 Elsevier Science. All rights reserved

Effect of superconductivity on the cubic to tetragonal structural transition due to a two-fold degenerate electronic band

International Nuclear Information System (INIS)

Ghatak, S.K.; Khanra, B.C.; Ray, D.K.

1978-01-01

The effect of the BCS superconductivity on the cubic to tetragonal structural transition arising from a two-fold degenerate electronic band is investigated within the mean field approximation. The phase diagram of the two transitions is given for a half filled esub(g)-band. Modification of the two transitions when they are close together is also discussed. (author)

Genética de coffea VI: independência dos fatores xc xc (xanthocarpa e br br (bronze em coffea arabica L.

Directory of Open Access Journals (Sweden)

C. A. Krug

1942-01-01

Full Text Available Em artigos anteriores (1, 2 os autores demonstraram que a cor amarela dos frutos e a coloração bronzeada das folhas novas são, em Coffea arabica L, controladas, cada uma, por um único par de fatores genéticos (respectivamente xc xc e Br Br. Os híbridos F1 no primeiro caso com plantas de frutos vermelhos, e no segundo com plantas de folhas novas verdes, demonstraram tratar-se de casos em que há dominância incompleta nesta geração, os frutos híbridos possuindo uma coloração vermelho clara e as folhas novas se apresentando com uma tonalidade bronze clara. Como algumas das hibridações realizadas envolviam, ao mesmo tempo, os dois caracteres em questão, apresentou-se a oportunidade para constatar se havia ou não independência entre os dois pares de fatores que controlam estes caracteres. Neste artigo apresentam-se os resultados das observações realizadas, tanto em diversas populações de F2 como também em dois back-crosses. Os dados confirmam plenamente a hipótese estabelecida, isto é, da independência entre os dois pares de fatores em questão (xc xc e Br Br. Este fato era esperado à vista do número relativamente elevado de cromosômios nas variedades cruzadas (2n = 44.In two previous publications (1,2 the authors demonstrated that in Coffea arabica L. yellow fruit color and bronze color of young leaves are each controled by one pair of genes (respectively xc xc and Br Br. The F1 hybrids, in the first instance between plants with yellow and red fruits and in the second instance between plants with bronze and green colored young leaves, showed incomplete dominance of both characters, the F1 fruits being of a light red color and the F1 young leaves of a light bronze one. As some of the crosses involved both pairs of genes, it was possible to find out wether they are linked or independent. In the present article the authors are publishing the results obtained with several F2 populations and also with 2 types of back crosses

ZrO2TETRAGONAL OBTENIDO POR EL MÉTODO DE PRECIPITACIÓN CONTROLADA

OpenAIRE

CAMPO CEBALLOS, DIEGO A.; RODRIGUEZ PÁEZ, JORGE E.

2011-01-01

En este trabajo se utilizó el método de precipitación controlada para sintetizar ZrO2 tetragonal estabilizado con óxido de calcio, CaO. Los sólidos obtenidos se caracterizaron utilizando análisis térmico diferencial y gravimétrico (ATD/TG), Espectroscopia Infrarroja con transformada rápida de Fourier (FT-IR), Difracción de Rayos X (DRX), y microscopia electrónica de transmisión (MET). Los resultados indican que al tratar el polvo cerámico a una temperatura de 600 ºC se obtiene ZrO2 con fase c...

Particle size and kind of mica in synthesis of nontoxic bronze and gold pearlescent pigments based on nanoencapsulated hematite

Directory of Open Access Journals (Sweden)

Maryam Hosseini-Zori

2015-12-01

Full Text Available Nano-encapsulated iron oxide in Zirconium oxide-coated mica pigments are thermally stable,innocuous to human health, non-combustible, and they do not conduct electricity. They could beapplied in several industries such as thermoplastics, cosmetics, food packaging, children toys, paints,automobiles coating, security purposes, and banknotes. Nowadays, they are highly desirable inceramic decoration. In the present study, intensively dark gold to bronze colored mica clay pigments,which were based on mica flakes covered with a layer of nano-iron oxide-Zirconium oxide particles,were prepared by homogeneous precipitation of iron nitrate and Zirconium chloride ammonia in thepresence of mica flakes in two kinds of ore clay-based phlogopite and muscovite minerals. The finalcolor was obtained by thermal annealing of precipitates at a temperature of 800◦C. The pigments werecharacterized by X-Ray Diffraction, Particle size analysis, Scanning electron microscopy,Transmission electron microscopy, X-Ray fluorescence, and Simultaneous thermal analysis. Resultsindicate that nano-encapsulated iron oxide in zirconia particles have been formed on mica flakes andkinds of clay-mica can be related to obtained shade from dark gold to bronze pearl. Higher particlesize of mica flakes about phlogopite type of mica introduced pearl effects with higher L* changes indifferent angles. Muscovite performed higher hue and better pearl effect than phlogopite.

Mongolian “Neolithic” and Early Bronze Age ground stone tools from the northern edge of the Gobi Desert

Directory of Open Access Journals (Sweden)

Joan S. Schneider

2016-10-01

Full Text Available The transition from the Mongolian Neolithic to the Bronze Age is not well understood. Within Ikh Nart Nature Reserve, over a period of five years, we identified a number of sites with dense surface artefact scatters and features that seem to represent this transition period. Evident in those concentrations are characteristic microblade cores, microblades, “thumbnail" flake scrapers, projectile points, ground stone tools, and stone features of unknown function. Between 2012 and 2014 we collected ground stone artefacts from four sites and sediment samples from three sites. With permission of Mongolian authorities, the artefacts from one site and sediment samples from three sites were sent for botanical analyses to the University of Texas, Austin, Environmental Archaeology Laboratory. Preliminary results indicate that plant remains are present on the ground stone artefacts: dendritic long-cells from a deep pore of one artefact and starch grains from the pores of six of the seven artefacts. These data present the first opportunity to understand what resources “Neolithic” people were processing with ground stone tools in this area and further our opportunity to better understand the little-known “Neolithic”-Early Bronze Age transition period in Central Asia. This paper describes the ground stone artefacts and further explores the results of data retrieved from some of these artefacts.

The transmissional and functional context of the lexical lists from Ḫattuša and from the contemporaneous traditions in Late-Bronze-Age Syria

NARCIS (Netherlands)

Scheucher, Tobias Simon

2012-01-01

The study attempts to reconstruct aspects of the culture and knowledge transfer as involved in the import of cuneiform writing from Mesopotamia to Anatolia and Syria in the Late Bronze Age. It therefore analyzes the manuscripts called 'lexical lists' that were excavated at the Anatolian and Syrian

Life in the fast lane: Settled pastoralism in the Central Eurasian Steppe during the Middle Bronze Age.

Science.gov (United States)

Judd, Margaret A; Walker, Jessica L; Ventresca Miller, Alicia; Razhev, Dmitry; Epimakhov, Andrey V; Hanks, Bryan K

2018-04-19

We tested the hypothesis that the purported unstable climate in the South Urals region during the Middle Bronze Age (MBA) resulted in health instability and social stress as evidenced by skeletal response. The skeletal sample (n = 99) derived from Kamennyi Ambar 5 (KA-5), a MBA kurgan cemetery (2040-1730 cal. BCE, 2 sigma) associated with the Sintashta culture. Skeletal stress indicators assessed included cribra orbitalia, porotic hyperostosis, dental enamel hypoplasia, and tibia periosteal new bone growth. Dental disease (caries, abscess, calculus, and periodontitis) and trauma were scored. Results were compared to regional data from the nearby Samara Valley, spanning the Early to Late Bronze Age (EBA, LBA). Lesions were minimal for the KA-5 and MBA-LBA groups except for periodontitis and dental calculus. No unambiguous weapon injuries or injuries associated with violence were observed for the KA-5 group; few injuries occurred at other sites. Subadults (age. Skeletal stress markers and injuries were uncommon among the KA-5 and regional groups, but a MBA-LBA high subadult mortality indicates elevated frailty levels and inability to survive acute illnesses. Following an optimal weaning program, subadults were at risk for physiological insult and many succumbed. Only a small number of individuals attained biological maturity during the MBA, suggesting that a fast life history was an adaptive regional response to a less hospitable and perhaps unstable environment. © 2018 Wiley Periodicals, Inc.

A preliminary X-ray diffraction study of the tetragonal superconducting oxide LaBa2Cu3O7-δ

International Nuclear Information System (INIS)

Hervieu, M.; Nguyen, N.; Michel, C.

1987-01-01

X-ray diffraction study of LaBa 2 Cu 3 O 7-δ showed that this tetragonal oxide exhibits an ordered oxygen deficient perovskite structure. It appears that the oxygen vacancy distribution differs from that observed for the orthorhombic superconductor YBa 2 Cu 3 O 7-δ . A structural model is proposed and discussed [fr

Stable carbon and oxygen isotope ratios of malachite from the patinas of ancient bronze objects

International Nuclear Information System (INIS)

Smith, A.W.

1978-01-01

13 C/ 12 C and 18 O/ 16 O ratios have been measured for 62 samples of the mineral malachite, taken from the patinas of ancient bronze objects (from Britain, Italy, Libya and China), in order to investigate any possible relationship which may exist between the isotope ratios and the burial conditions of the objects. The results indicate that the isotope ratios are controlled by complex factors related to the climate, vegetation and soil type at the burial site. It is suggested that the technique might be used, given favourable circumstances, in the characterization of patinas and as a possible aid in the detection of synthetic patination. (author)

Microstructural evolution and stability of tetragonal precipitates in Y2O3 partially-stabilized ZrO2 single crystals

International Nuclear Information System (INIS)

Martinez-Fernandez, J.; Jimenez-Melendo, M.; Dominguez-Rodriguez, A.

1995-01-01

The microstructure and morphology of tetragonal precipitates (t-ZrO 2 ) in yttria partially-stabilized zirconia single crystals containing various amounts of Y 2 O 3 (3, 4, 4.7 and 5.8 mol%) have been studied as a function of aging time at 1,600 C in air. The precipitate size and volume fraction of t-ZrO 2 phase were determined using transmission electron microscopy. The evolution of the precipitate volume fraction with aging time indicated that the precipitation reaction was completed after 24 h of annealing, in agreement with the values of the Y 2 O 3 composition in the matrix measured by analytical electron microscopy. Further aging coarsened the precipitates which joined together forming fiber-like particles of several micrometers in length and remaining untransformed despite their large size. The stability of the t-ZrO 2 precipitates against the tetragonal to monoclinic transformation in the ZrO 2 -Y 2 O 3 system seems to be related to interactions between precipitates due to coherency stresses rather than with their morphological characteristics

Armorican arrowhead biographies: Production and function of an Early Bronze Age prestige good from Brittany (France

Directory of Open Access Journals (Sweden)

Clément Nicolas

2014-09-01

Full Text Available Brittany can pride itself on the Armorican arrowheads found in Early Bronze Age graves (2150-1700 BC. In the present state of knowledge, these are the only specialized craft products in knapped flint produced in this region at the western edge of continental Europe. Admired since the 19th century, these flint arrowheads have never really been studied. Due to the wealth of graves and grave-goods, a relatively precise study can be undertaken of the development of these craft products, despite the low number of reliable radiocarbon dates.These arrowheads are characterized by a well-defined type (pointed tang and oblique barbs most often combined with ogival form. Raw materials show the selection of a high quality yellow translucent flint, of which the origin has to be sought at more than 400 kilometers (Lower Turonian flint from Cher Valley. From a technical point of view, Armorican arrowheads reveal a great mastery of retouch by pressure-flaking. This skill is written in stone by the perfection of forms, the extreme thinness (until 2,5 mm thick and very long barbs (until 25 mm long. Such work could not have been done without the use of copper, even bronze, awls. Moreover, some marks may testify to the implication of these tools. On 549 arrowheads that have reached to us, none of them presents diagnostical impact features. However, use-wear analysis indicates that most of them were hafted (adhesive traces, bright spots, blunt edges. These facts suggest that they are less functional arrowheads than objects for the show. In the graves, Armorican arrowheads are frequently set down carefully in wooden boxes taking the shaft off.The Armorican arrowheads with their exotic raw materials, their high-degree of technicality, and their absence of use, have all features of a prestige good. They have been discovered by dozens in few graves under barrows with very rich funeral items (bronze daggers decorated with golden pins, precious bracers, silver beakers

Alumina reinforced tetragonal zirconia (TZP) composites. Final technical report, July 1, 1993--December 31, 1996

International Nuclear Information System (INIS)

Shetty, D.K.

1997-01-01

This final technical report summarizes the significant research results obtained during the period July 1, 1993 through December 31, 1996 in the DOE-supported research project entitled, open-quotes Alumina Reinforced Tetragonal Zirconia (TZP) Compositesclose quotes. The objective of the research was to develop high-strength and high-toughness ceramic composites by combining mechanisms of platelet, whisker or fiber reinforcement with transformation toughening. The approach used included reinforcement of Celia- or yttria-partially-stabilized zirconia (Ce-TZP or Y-TZP) with particulates, platelets, or continuous filaments of alumina

Growth kinetics of tetragonal and monoclinic ZrO{sub 2} crystallites in 3 mol% yttria partially stabilized ZrO{sub 2} (3Y-PSZ) precursor powder

Energy Technology Data Exchange (ETDEWEB)

Kuo, Chih-Wei [Department of Resources Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Lee, Kuen-Chan [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Yen, Feng-Lin, E-mail: flyen@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Shen, Yun-Hwei [Department of Resources Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Lee, Huey-Er [Department of Dentistry, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Department of Dentistry, Kaohsiung Medical University, Chung Ho Memorial Hospital, 100 Tzyou 1st Road, Kaohsiung 807, Taiwan (China); Wen, Shaw-Bing [General Education Center, Meiho Institute of Technology, 23 Pingguang Road, Neipu, Pingtung 91202, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Stack, Margaret Mary [Department of Mechanical and Aerospace Engineering, University of Strathclyde, 75 Montrose Street, Glasgow (United Kingdom)

2014-04-01

Highlights: • The crystalline structures were composed of tetragonal and monoclinic ZrO{sub 2}. • Growth kinetics of t-ZrO{sub 2} in the 3Y-PSZ precursor powder is described as: D{sub te}{sup 2}=(4.57±0.55)t{sup 0.12±0.02}exp(-((24.79±0.38)×10{sup 3})/(RT) ). • Growth kinetics of m-ZrO{sub 2} in the 3Y-PSZ precursor powder is described as: D{sub m}{sup 2}=(4.40±1.63)t{sup 0.17±0.08}exp(-((66.47±3.97)×10{sup 3})/(RT) ). - Abstract: The growth kinetics of tetragonal and monoclinic ZrO{sub 2} crystallites in 3 mol% yttria partially stabilized ZrO{sub 2} (3Y-PSZ) precursor powder has been investigated using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) specific surface area analysis, transmission electron microscopy (TEM) and high resolution TEM (HRTEM). After calcination of the 3Y-PSZ precursor powder between 773 and 1073 K for 2 h, the crystalline structures were composed of tetragonal and monoclinic ZrO{sub 2} as the primary and secondary phases, respectively. When the 3Y-PSZ precursor powder was calcined at 773 K for 2 h, the BET specific surface area was 97.13 m{sup 2}/g, which is equivalent to a particle size of 10.30 nm. The crystallite sizes determined via XRD and BET agreed well, indicating that the powder was virtually non-agglomerated. The growth kinetics of tetragonal and monoclinic ZrO{sub 2} crystallite isothermal growth in the 3Y-PSZ precursor powder are described by: D{sub te}{sup 2}=(4.57±0.55)t{sup 0.12±0.02}exp(-((24.79±0.38)×10{sup 3})/(RT) ) and D{sub m}{sup 2}=(4.40±1.63)t{sup 0.17±0.08}exp(-((66.47±3.97)×10{sup 3})/(RT) ), respectively, for 773K≤T≤1073K. D{sub te} and D{sub m} denote the crystallite size of tetragonal and monoclinic ZrO{sub 2} at time t and temperature T, respectively.

Iron and silicon effect on the phase composition of nickel-beryllium bronzes

International Nuclear Information System (INIS)

Zakharov, A.M.; Zakharov, M.V.; Ajvaz'yan, N.G.

1977-01-01

In order to specify phase composition and strengthening heat treatment conditions for nickel beryllium bronzes that are promising electrode materials for welding of high strength steels and nickel-base superalloys, the primary section of the quinternary Cu-Ni-Be-Fe-S system was studied at constant nickel and beryllium concentration and varying silicon and iron concentration (max. 4% of every element). The study was made using the metallographic and x-ray phase techniques, determination of alloy solidus temperature, and exessphase microhardness testing. Silicon additions are shown to decrease abruptly and those of iron, in contrast, somewhat to raise the solidus temperature of ternary Cu + 2% Ni + 0.3% Be alloy. When added concurrently, iron compensates for the damaging silicon effect on the solidus temperature of Cu-Ni-Be alloys. The excess phases formed can be used as strengthening agents of Cu-Ni-Be-Si-Fe alloys during quenching and subsequent aging

Fine structure of spectra of a bound exciton in tetragonal zinc diphosphide

International Nuclear Information System (INIS)

Syrbu, N.N.; Morozova, V.I.; Stratan, G.I.

1989-01-01

Investigation into the low-temperature luminescence spectra recorded in different crystal geometry relative to the direction of incident radiation wave vector, has demonstrated the existence of saddle-shaped valent zone ceiling near k=0 in zinc tetragonal diphosphide monocrystals. Binding energies of free (2.2085 eV) and bound (A(2.1943eV)B(2.1765eV), C(2.1447eV)) excitons as well as the phonon energy value are determined by investigations into absorption spectrum and radiative recombination. Phonon-free lines of bound A 0 and C 0 excitons are splitted into 2.2 and 0.3 MeV respectively. The band exciton singlet-triplet state splittings in a magnetic field and their field dependences are obtained. The spectroscopic splitting factor g=1.9 is determined

Residual stress relief due to fatigue in tetragonal lead zirconate titanate ceramics

International Nuclear Information System (INIS)

Hall, D. A.; Mori, T.; Comyn, T. P.; Ringgaard, E.; Wright, J. P.

2013-01-01

High energy synchrotron XRD was employed to determine the lattice strain ε{111}and diffraction peak intensity ratio R{200}in tetragonal PZT ceramics, both in the virgin poled state and after a bipolar fatigue experiment. It was shown that the occurrence of microstructural damage during fatigue was accompanied by a reduction in the gradient of the ε{111}–cos 2 ψ plot, indicating a reduction in the level of residual stress due to poling. In contrast, the fraction of oriented 90° ferroelectric domains, quantified in terms of R{200}, was not affected significantly by fatigue. The change in residual stress due to fatigue is interpreted in terms of a change in the average elastic stiffness of the polycrystalline matrix due to the presence of inter-granular microcracks

Residual stress relief due to fatigue in tetragonal lead zirconate titanate ceramics

Science.gov (United States)

Hall, D. A.; Mori, T.; Comyn, T. P.; Ringgaard, E.; Wright, J. P.

2013-07-01

High energy synchrotron XRD was employed to determine the lattice strain ɛ{111} and diffraction peak intensity ratio R{200} in tetragonal PZT ceramics, both in the virgin poled state and after a bipolar fatigue experiment. It was shown that the occurrence of microstructural damage during fatigue was accompanied by a reduction in the gradient of the ɛ{111}-cos2 ψ plot, indicating a reduction in the level of residual stress due to poling. In contrast, the fraction of oriented 90° ferroelectric domains, quantified in terms of R{200}, was not affected significantly by fatigue. The change in residual stress due to fatigue is interpreted in terms of a change in the average elastic stiffness of the polycrystalline matrix due to the presence of inter-granular microcracks.

First-principles comparison of the cubic and tetragonal phases of Mo3Sb7

KAUST Repository

Nazir, Safdar; Auluck, Sushil V.; Pulikkotil, Jiji Thomas Joseph; Singh, Nirpendra; Schwingenschlö gl, Udo

2011-01-01

Using ab initio density functional based methods, we study the normal metal state properties of the ∼3 K Mo3Sb7 superconductor, in its high temperature cubic and low temperature tetragonal structures. Although the density of states at the Fermi energy is reasonably high in both structures, our calculations unequivocally show that there exists no long range magnetic ordering in this system. We also address the optical properties of the compound. The magnetism in Mo3Sb7 is studied by fixed spin moment calculations, which yield a shallow non-magnetic minimum, thus inferring propensity to a magnetic instability. © 2011 Elsevier B.V. All rights reserved.

Texture of poled tetragonal PZT detected by synchrotron X-ray diffraction and micromechanics analysis

International Nuclear Information System (INIS)

Hall, D.A.; Steuwer, A.; Cherdhirunkorn, B.; Withers, P.J.; Mori, T.

2005-01-01

The texture and lattice elastic strain due to electrical poling of tetragonal PZT (lead zirconate titanate) ceramics have been measured using high energy synchrotron X-ray diffraction. It is shown that XRD peak intensity ratios associated with crystal planes of the form {002}, {112} and {202} exhibit a linear dependence on cos-bar 2 Ψ, where Ψ represents the orientation angle between the plane normal and the macroscopic poling axis. The observed dependence of texture and lattice strain on the grain orientation can be understood on the basis that the macroscopic strain due to poling is the average of the poling strains of all the individual grains

First-principles comparison of the cubic and tetragonal phases of Mo3Sb7

KAUST Repository

Nazir, Safdar

2011-03-01

Using ab initio density functional based methods, we study the normal metal state properties of the ∼3 K Mo3Sb7 superconductor, in its high temperature cubic and low temperature tetragonal structures. Although the density of states at the Fermi energy is reasonably high in both structures, our calculations unequivocally show that there exists no long range magnetic ordering in this system. We also address the optical properties of the compound. The magnetism in Mo3Sb7 is studied by fixed spin moment calculations, which yield a shallow non-magnetic minimum, thus inferring propensity to a magnetic instability. © 2011 Elsevier B.V. All rights reserved.

Effects of Mo-doping on microstructure and near-infrared shielding performance of hydrothermally prepared tungsten bronzes

Energy Technology Data Exchange (ETDEWEB)

Wang, Qingjuan; Li, Can; Xu, Wenai; Zhao, Xiaolin; Zhu, Jingxin [Laboratory of Green Energy Materials and Storage Systems, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Jiang, Haiwei, E-mail: tyjmx@163.com [Laboratory of Green Energy Materials and Storage Systems, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Kang, Litao, E-mail: kangltxy@163.com [Laboratory of Green Energy Materials and Storage Systems, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences (China); Zhao, Zhe [School of Materials Science & Engineering, Shanghai Institute of Technology, Shanghai 201418 (China)

2017-03-31

Highlights: • Mo-doped tungsten bronzes were hydrothermally synthesized at 80 °C. • Samples transformed from hexagonal to monoclinic structure with Mo-content increase. • 1.5% Mo-doped samples show the best near-infrared shielding performance. • High Mo-doping weakens localized surface plasmon resonance (LSPR) absorption and thus NIR shielding performance. • Small polaron absorption seems to be less affected by Mo-doping. - Abstract: Both Mo and W belong to VIB-sub-group, and possess similar ionic radii, electronegativity and oxide lattice configuration. Herein, Mo-doped (0–80 at.%) tungsten bronzes, M{sub x}WO{sub 3}, were hydrothermally prepared to systematically explore the influence of Mo-doping on their micro-structure and optical performance. The products adopted a hexagonal structure within 6 at.% Mo-doping, and transformed into a monoclinic phase with higher Mo-doping content. Further tests suggested that 1.5 at.% Mo-doping is beneficial for the formation of pure hexagonal phase and uniform nano-rod morphology. Optical measures showed that all samples exhibited high and comparable visible transmittance (70–80%), but a very different near infrared (NIR) shielding ability. The sample doped with 1.5 at.% Mo demonstrated the best NIR shielding ability with a transmittance minimum of 20% at 1300 nm. Further increase of Mo-doping dosage remarkably deteriorated NIR shielding ability by depressing the absorption of localized surface plasmon resonance (LSPR). However, the optical absorption from small-polaron was less influenced by the introduction of Mo. As a result, Mo-doping caused an evident blue shift of the infrared absorption peaks from 1350 to 750 nm.

FENIX experimental results of large-scale CICC made of bronze-processed Nb3Sn strands

International Nuclear Information System (INIS)

Shen, S.S.; Felker, B.; Moller, J.M.; Parker, J.M.; Isono, T.; Yasukawa, Y.; Hosono, F.; Nishi, M.

1994-01-01

The Fusion ENgineering International eXperiments (FENIX) Test Facility recently has successfully complete the testing of a pair of Nb 3 rSn cable-in-conduit conductors developed by the Japan Atomic Energy Research Institute. These conductors, made of bronze-processed strands, were designed to operate stably with 40-kA transport current at a magnetic field of 13 T. In addition to the measurements of major design parameters such as current-sharing temperature, FENIX provided several experiments specifically designed to provide results urgently needed by magnet designers. Performed experiments include measurements of ramp-rate limit, current-distribution, stability, and joint performance. This paper presents the design and results of these special experiments

Agro-pastoral diets in southern Italy from the Neolithic to the Bronze Age

DEFF Research Database (Denmark)

Arena, Fabiola; Mannino, Marcello; Philippsen, Bente

. In particular, this method of palaeodietary reconstruction allows us to establish the ecosystem of origin of foods (terrestrial, freshwater and/or marine) and the type of diet (vegetarian, omnivorous or carnivorous). Our analyses on 33 human and 12 faunal bone collagen extracts attest that the diets......The period from the Neolithic to the Bronze Age was a time of considerable socio-cultural and economic change, which affected human diets. To improve our understanding of dietary change in communities living in the south of Italy during this period, we have undertaken stable carbon and nitrogen......), Basilicata (Murgia Timone, Grotta Funeraria and Toppo d’Aguzzo) and Apulia (Ipogeo dei Bronzi). Carbon and nitrogen isotope analyses inform us mainly on the intake of dietary protein, although, in diets characterized by limited meat consumption, they also provide us with information on plant consumption...

Theoretical studies of the local structure and electron paramagnetic resonance parameters for tetragonal VO{sup 2+} in C{sub 6}H{sub 7}KO{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Zhou, Ping [Chongqing Jiaotong Univ. (China). School of Science; Li, Ling [Sichuan University of Arts and Science, Dazhou (China). Dept. of Maths and Finance-Economics

2015-07-01

The optical spectra, electron paramagnetic resonance parameters (i.e., the spin Hamiltonian parameters, including paramagnetic g factors and the hyperfine structure constants A{sub i}) and the local distortion structure for the tetragonal VO{sup 2+} in C{sub 6}H{sub 7}KO{sub 7} are theoretically studied based on the crystal-field theory and three-order perturbation formulas of a 3d{sup 1} centre in tetragonal site. The magnitude of orbital reduction factor, core polarisation constant κ, and local structure parameters are obtained by fitting the calculated optical spectra and electron paramagnetic resonance parameters to the experimental values. The theoretical results are in reasonable agreement with the experimental values.

Crystal structure of the tetragonal polymorph of bis(1-ethyl-3-methylimidazolium tetrabromidocadmate

Directory of Open Access Journals (Sweden)

Tamara Đorđević

2016-07-01

Full Text Available Both unique Cd atoms in the tetragonal polymorph of bis(1-ethyl-3-methylimidazolium tetrabromidocadmate, (C6H11N22[CdBr4], occupy special positions (site symmetry -4. The crystal structure consists of isolated tetrahedral [CdBr4]2− anions which are surrounded by 1-ethyl-3-methylimidazolium cations. The methyl and ethyl side chains of the cations show positional disorder in a 0.590 (11:0.410 (11 ratio. In the crystal, (C6H11N2+ cations display three weak C—H...Br hydrogen-bond interactions through the imidazolium ring H atoms with the Br− ligands of the surrounding complex anions. The alkyl groups of the side chains are not involved in hydrogen bonding.

The Bronze Age in the Northwestern of Iberian Peninsula: an analysis from funerary practices

Directory of Open Access Journals (Sweden)

Bettencourt, Ana M. S.

2010-06-01

Full Text Available From the analysis of the funerary practices and of their integration in the different chronological-cultural contexts where they develop, the author works out a new interpretation of the mechanism of negotiation of power and the promotion of social identity through the Bronze Age of the NW Iberian Peninsula. When studying an area so wide she distinguishes two great trends in the type and distribution of the funerary architectures throughout the Bronze Age that she associates with different ways of interaction with, and perception of, the world. Thus, she argues that the necropolises of “cloudy” tombs (cists without tumuli, plain graves and pits, located in areas of great agricultural potential and close to the settlements, may have been constructed by sedentary communities, very involved in agricultural activities, with a great sense of territoriality and a great control over, and deep knowledge of, the territory. On the other hand the communities involved with mountain landscapes, eventually more related to cattle and with ways of life that would imply greater mobility, were responsible for the construction of more visible funerary structures, such as small tumuli of megalithic tradition, located away from the settlements. In relation to the social role of the corpse, the author argues for the Early Bronze Age, that, the occupation of new territories, the emergence of a new form of community interaction with the environment and the emergence of new mechanisms of power and legitimacy of the territory were materialized in burial practices and in the social role of some corpses, in copper and gold grave goods. This social role was represented in old and new places. From the Middle Bronze Age she assumes that the corpse loses importance in collective terms and that death becomes more familiar. The new settings of power negotiation and social identity are transferred to other contexts of action more connected with the sphere of the living

Performance and Carcass characteristics of broad breasted bronze toms fed radappertized Diet

International Nuclear Information System (INIS)

Farag, El-Din.M.H.; Mohamed, F.A.

1999-01-01

The effect of irradiated complete diets at dose level of 25 KGy was studied in broad breasted bronze tome evaluating their growing performances as well as characteristics of the carcasses. Two experimental groups received irradiated and non irradiated diets for 18 weeks (from the 5 t h to the 23 r d week of age). Four toms per treatment at the age of 23 weeks were slaughtered and the carcass was dissected. Radappertized diets improved body weight gain, feed consumption and feed conversion and reduced mortality rate. No significant differences were observed between toms fed processed and non processed diets on carcasses components, while the gizzard weight was greater for those fed the processed diets. Dressing and drawn weights in toms fed processed diets were 3% higher than in those fed non processed diets. The results suggest that sterilization of turkeys feed may have a beneficial effect on the body weight and deed conversion of turkeys consuming these diets without harmful effect on the bird

The examination, analysis and conservation of a bronze Egyptian Horus statuette

Energy Technology Data Exchange (ETDEWEB)

Smith, A. [Conservation Department, Ditsong: National Museum of Cultural History, PO Box 28088, Sunnyside, Pretoria 0132 (South Africa); Botha, H. [South African Institute for Objects Conservation, PO Box 122, Joubertina 6410 (South Africa); Beer, F.C. de, E-mail: frikkie.debeer@necsa.co.za [Radiation Science, Necsa, PO Box 582, Pretoria 0001 (South Africa); Ferg, E. [Department of Chemistry, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

2011-09-21

The production techniques, corrosive deterioration, conservation and questions regarding authenticity of a small Egyptian bronze statuette of the Child Horus (in the collection of the Ditsong: National Museum of Cultural History in Pretoria) was scientifically examined and analysed. The statuette dates to Egypt's 12th Dynasty. When the statuette was damaged, it was considered the appropriate time to obtain valuable information about its history and background through scientific research. Neutron tomography (NT), a relatively new non-destructive technique (NDT) to the South African R and D community to study museum objects, was applied to perform this research. The results from NT were supported by additional tests done through XRF and XRD analyses of samples taken from the damaged statuette. Results revealed that the lost-wax method was used in the manufacturing process. The extent of the restoration and materials used can be verified and as a result the deterioration of the object can now be monitored. This paper describes in detail the analytical techniques used in the study and how it contributed to the conservation of the statuette and its authenticity.

EXPERIMENTAL MONTAGE USED TO STUDY THE VIBRATION OF THE DRILL TOOL IN THE PROCESS OF MANUFACTURING THE BRONZE MATERIALS

Directory of Open Access Journals (Sweden)

Cosmin-Mihai MIRIŢOIU

2013-05-01

Full Text Available In this paper we present the experimental setup used to study the vibration of the drill tool, during the drilling of the bronze products. In this paper the vibrations are analyzed during the drilling on the universal lathe machines. This time, the tool is fixed in the movable boring head and will make a translation movement with constant feeding, and the workpiece spins around its axis of symmetry and it is fixed in the spindle head stock of the universal lathe machine

Lead-free, bronze-based surface layers for wear resistance in axial piston hydraulic pumps

Energy Technology Data Exchange (ETDEWEB)

Vetterick, Gregory Alan [Iowa State Univ., Ames, IA (United States)

2010-01-01

Concerns regarding the safety of lead have provided sufficient motivation to develop substitute materials for the surface layer on a thrust bearing type component known as a valve plate in axial piston hydraulic pumps that consists of 10% tin, 10% lead, and remainder cooper (in wt. %). A recently developed replacement material, a Cu-10Sn-3Bi (wt.%) P/M bronze, was found to be unsuitable as valve plate surface layer, requiring the development of a new alloy. A comparison of the Cu-1-Sn-10Pb and Cu-10Sn-3Bi powder metal valve plates showed that the differences in wear behavior between the two alloys arose due to the soft phase bismuth in the alloy that is known to cause both solid and liquid metal embrittlement of copper alloys.

Cubic to tetragonal phase transition of Tm3+ doped nanocrystals in oxyfluoride glass ceramics

International Nuclear Information System (INIS)

Li, Yiming; Fu, Yuting; Shi, Yahui; Zhang, Xiaoyu; Yu, Hua; Zhao, Lijuan

2016-01-01

Tm 3+ ions doped β-PbF 2 nanocrystals in oxyfluoride glass ceramics with different doping concentrations and thermal temperatures are prepared by a traditional melt-quenching and thermal treatment method to investigate the structure and the phase transition of Tm 3+ doped nanocrystals. The structures are characterized by X-ray diffraction Rietveld analysis and confirmed with numerical simulation. The phase transitions are proved further by the emission spectra. Both of the doping concentration and thermal temperature can induce an O h to D 4h site symmetry distortion and a cubic to tetragonal phase transition. The luminescence of Tm 3+ doped nanocrystals at 800 nm was modulated by the phase transition of the surrounding crystal field

First principles study of the structural and electronic properties of double perovskite Ba{sub 2}YTaO{sub 6} in cubic and tetragonal phases

Energy Technology Data Exchange (ETDEWEB)

Deluque Toro, C.E., E-mail: deluquetoro@gmail.com [Grupo de Nuevos Materiales, Universidad Popular del Cesar, Valledupar (Colombia); Rodríguez M, Jairo Arbey [Grupo de Estudios de Materiales—GEMA, Departamento de Física, Universidad Nacional de Colombia, AA 5997 Bogotá DC (Colombia); Landínez Téllez, D.A. [Grupo de Física de Nuevos Materiales, Departamento de Física, Universidad Nacional de Colombia, AA 5997 Bogotá DC (Colombia); Moreno Salazar, N.O. [Departamento de Física, Universidade Federal de Sergipe (Brazil); Roa-Rojas, J. [Grupo de Física de Nuevos Materiales, Departamento de Física, Universidad Nacional de Colombia, AA 5997 Bogotá DC (Colombia)

2014-12-15

The Ba{sub 2}YTaO{sub 6} double perovskite presents a transition from cubic (Fm−3m) to tetragonal structure (I4/m) at high temperature. In this work, we present a detailed study of the structural and electronic properties of the double perovskite Ba{sub 2}YTaO{sub 6} in space group Fm−3m and I4/m. Calculations were made with the Full-Potential Linear Augmented Plane Wave method (FP-LAPW) within the framework of the Density Functional Theory (DFT) with exchange and correlation effects in the Generalized Gradient (GGA) and Local Density (LDA) approximations. From the minimization of energy as a function of volume and the fitting of the Murnaghan equation some structural characteristics were determined as, for example, total energy, lattice parameter (a=8.50 Å in cubic phase and a=5.985 Å and c=8.576 Å in tetragonal), bulk modulus (135.6 GPa in cubic phase and 134.1 GPa in tetragonal phase) and its derivative. The study of the electronic characteristics was performed from the analysis of the electronic density of states (DOS). We find a non-metallic behavior for this with a direct band gap of approximately 3.5 eV and we found that the Ba{sub 2}YTaO{sub 6} (I4/m) phase is the most stable one. {sup ©} 2013 Elsevier Science. All rights reserved.

Thermal stability of simple tetragonal and hexagonal diamond germanium

Science.gov (United States)

Huston, L. Q.; Johnson, B. C.; Haberl, B.; Wong, S.; Williams, J. S.; Bradby, J. E.

2017-11-01

Exotic phases of germanium, that form under high pressure but persist under ambient conditions, are of technological interest due to their unique optical and electrical properties. The thermal evolution and stability of two of these exotic Ge phases, the simple tetragonal (st12) and hexagonal diamond (hd) phases, are investigated in detail. These metastable phases, formed by high pressure decompression in either a diamond anvil cell or by nanoindentation, are annealed at temperatures ranging from 280 to 320 °C for st12-Ge and 200 to 550 °C for hd-Ge. In both cases, the exotic phases originated from entirely pure Ge precursor materials. Raman microspectroscopy is used to monitor the phase changes ex situ following annealing. Our results show that hd-Ge synthesized via a pure form of a-Ge first undergoes a subtle change in structure and then an irreversible phase transformation to dc-Ge with an activation energy of (4.3 ± 0.2) eV at higher temperatures. St12-Ge was found to transform to dc-Ge with an activation energy of (1.44 ± 0.08) eV. Taken together with results from previous studies, this study allows for intriguing comparisons with silicon and suggests promising technological applications.

Discrepancies in 14C dating as illustrated from the Egyptian new and middle kingdoms and from the Aegean bronze age and neolithic

International Nuclear Information System (INIS)

Hood, S.

1978-01-01

14 C dates available for the Middle and New Kingdoms in Egypt and for the Bronze Age and Neolithic in the Aegean are examined. The possibility is explored that calibrated dates vary from tree-ring dates by different margins in Egypt and the Aegean during the second millenium B.C. Apparent inconsistencies between 14 C dates from different Neolithic sites in the Aegean area are also noted. (author)

Aarne Michaël Tallgren and the International Discussion on the Bronze Age of Russia

Directory of Open Access Journals (Sweden)

Timo Salminen

2017-04-01

Full Text Available This paper is on international scholarly discussion on the Bronze Age of Russia from 1908 until 1939, and in particular on the related role of the internationally renowned Finnish archaeologist Aarne Michaël Tallgren (1885–1945. How did a social network of researchers produce new interpretations and what were the key factors that distinguished the participants in the discussion? Was it a continuous process or a series of sudden changes? How did different ideological backgrounds influence the interpretations? In Western Europe, Tallgren’s most important interlocutors were Gero von Merhart, V Gordon Childe and Ellis H Minns, and in Russia V A Gorodcov and A A Spicyn. The paper is mainly based on correspondence between Tallgren and his colleagues.

Effect of structural packing on the luminescence properties in tungsten bronze compounds M{sub 2}KNb{sub 5}O{sub 15} (M=Ca, Sr, Ba)

Energy Technology Data Exchange (ETDEWEB)

Yin Xin; Shi Liu [State Key Laboratory of High Performance Ceramics and Superfine Microstructures and CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Wei Ang, E-mail: iamawei@njupt.edu.cn [Key Laboratory for Organic Electronics and Information Displays, 9 Wenyuan Road, Nanjing 210046 (China); Wan Dongyun; Wang Yaoming [State Key Laboratory of High Performance Ceramics and Superfine Microstructures and CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Huang Fuqiang, E-mail: huangfq@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructures and CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

2012-08-15

Tungsten bronze compounds M{sub 2}KNb{sub 5}O{sub 15} (M=Ca, Sr, Ba) were successfully synthesized, and the luminescence properties were investigated. Among the three compounds, Ca{sub 2}KNb{sub 5}O{sub 15} showed an obviously broad band of host luminescence at 460 nm with exciting at 269 nm. By doping Eu{sup 3+} into the M sites, Ca{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+} displayed strong red emission from Eu{sup 3+} ions characteristic transitions, nearly four times higher than Sr{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+} and seven times higher than Ba{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+}. Crystal packing factor (PF) was introduced to account for this luminescence difference, lower PF being correlated to higher luminescence intensity for perovskite-related structure. Both the as-prepared compounds and the literature examples were proved to fit this correlation. This can be explained through the influence of the structural packing on the environment distortion and crystal field splitting of the doping site. - Graphical abstract: Tungsten bronze compounds M{sub 2}KNb{sub 5}O{sub 15} (M=Ca, Sr, Ba) show the dependence of luminescence properties on structural packing, among which Ca{sub 2}KNb{sub 5}O{sub 15} has the superior luminescence. Highlights: Black-Right-Pointing-Pointer Tungsten bronze compounds were synthesized by solid state reaction. Black-Right-Pointing-Pointer Ca{sub 2}KNb{sub 5}O{sub 15} displayed remarkably blue host luminescence. Black-Right-Pointing-Pointer Ca{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+} showed more intense red emission than M{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+} (M=Sr, Ba). Black-Right-Pointing-Pointer The relationship between crystal packing factor and luminescence was obtained.

CONTRIBUTIONS TO THE STUDY OF THE VIBRATIONS FREQUENCY OF THE DRILL TOOL IN THE PROCESS OF MANUFACTURING THE BRONZE MATERIALS

Directory of Open Access Journals (Sweden)

Cosmin-Mihai MIRIŢOIU

2013-05-01

Full Text Available In this paper we present the experimental testings used to study the vibration of the drill tool, during the drilling of the bronze products. We have used the experimental setup presented in Miriţoiu (2013[1]. In this paper the vibrations are analyzed during the drilling on the universal lathe machines. The main purpose of to find a correlation between the cutting speed and the frequency of the vibration by using the experimental results and the regression analysis

Corrosion evaluation of multi-pass welded nickel–aluminum bronze alloy in 3.5% sodium chloride solution: A restorative application of gas tungsten arc welding process

International Nuclear Information System (INIS)

Sabbaghzadeh, Behnam; Parvizi, Reza; Davoodi, Ali; Moayed, Mohammad Hadi

2014-01-01

Highlights: • Corrosion of GTA welded nickel–aluminum bronze (C95800) was studied. • Drastic microstructural changes occurred during the welding operations. • The β′ and α phases acts as anode and cathode, correspondingly, in weld region. • A few nanoamperes couple current was measured in ZRA test as galvanic corrosion. • Corrosion resistance of weld parts could not be weakened in marine environments. - Abstract: In this research, the corrosion behavior of a gas tungsten arc welded nickel–aluminum bronze (NAB) alloy is investigated by DC and AC electrochemical techniques in 3.5% sodium chloride solution. Regarding the electrochemical impedance spectroscopy and potentiodynamic results, uniform corrosion resistance of instantly immersed weld and base samples are almost analogous and increased (more in weld region) during the immersion times. Moreover, zero resistant ammeter results demonstrated that the few nanoampere galvanic currents are attributed to microstructural and morphological differences between these two regions. Therefore, the welding procedure could not deteriorate the general corrosion resistance of the restored damaged NAB parts operating in marine environments

A catastrophic event in Lake Geneva region during the Early Bronze Age?

Science.gov (United States)

Kremer, Katrina; Yrro, Blé; Marillier, François; Hilbe, Michael; Corboud, Pierre; Rachoud-Schneider, Anne-Marie; Girardclos, Stéphanie

2013-04-01

Similarly to steep oceanic continental margins, lake slopes can collapse, producing large sublacustrine landslides and tsunamis. Lake sediments are excellent natural archives of such mass movements and their study allows the reconstructions of these prehistoric events, such as the 563 AD large tsunami over Lake Geneva (Kremer et al, 2012). In Lake Geneva, more than 100 km of high-resolution seismic reflection profiles reveal the late Holocene sedimentation history. The seismic record shows a succession of five large lens-shaped seismic units (A to I), characterized by transparent/chaotic seismic facies with irregular lower boundaries, and interpreted as mass-movement deposits. These units are interbedded with parallel, continuous and strong amplitude reflections, interpreted as the 'background' lake sediments. The oldest dated mass movement (Unit D) covers a surface of 22 km2 in the deep basin, near the city of Lausanne. This deposit has an estimated minimum volume of 0.18 km3 and thus was very likely tsunamigenic (Kremer et al, 2012). A 12-m-long sediment core confirms the seismic interpretation of the mass movement unit and shows that the uppermost 3 m of Unit D are characterized by deformed hemipelagic sediments topped by a 5 cm thick turbidite. This deposit can be classified as a slump whose scar can be interpreted in the seismic data and visualized by multibeam bathymetry. This slump of Lausanne was likely triggered by an earthquake but a spontaneous slope collapse cannot be excluded (Girardclos et al, 2007). Radiocarbon dating of plant macro-remains reveals that the unit D happened during Early Bronze Age. Three other mass wasting deposits occurred during the same time period and may have been triggered during the same event, either by a single earthquake or by a tsunami generated by the slump of Lausanne. Although the exact trigger mechanism of the all these mass-wasting deposits remains unknown, a tsunami likely generated by this event may have affected the

Low temperature electron microscopy on the cubic-tetragonal transformation of V3Si

Science.gov (United States)

Onozuka, T.; Ohnishi, N.; Hirabayashi, M.

1988-04-01

The cubic-tetragonal martensitic transition of V3Si and its precursor have been investigated in the temperature range from 13 K to 80 K using a 1 MV electron microscope with a double-tilting cold stage. Below the transition temperature Tm = 19 K, fine twin lamellae appear parallel to {110} plane traces, being connected continuously with mottled striations having the same orientation. Fine striations along {110} traces or so-called tweeds are observed below 50 K at the precursor of the structural phase transition. The image contrast of mottled striations and tweed patterns is attributed to the presence of lattice distortion owing to the softening of the shear modulus. Reversible changes of the patterns recorded with a TV-VTR system during cooling and heating processes were discussed briefly.

Dependence of e31,f on polar axis texture for tetragonal Pb(Zrx,Ti1-x)O3 thin films

Science.gov (United States)

Yeager, Charles B.; Ehara, Yoshitaka; Oshima, Naoya; Funakubo, Hiroshi; Trolier-McKinstry, Susan

2014-09-01

It was shown by Ouyang et al. [Appl. Phys. Lett. 86, 152901 (2005)] that the piezoelectric e31,f coefficient is largest parallel to the spontaneous polarization in tetragonal PbZrxTi1-xO3 (PZT) films. However, the expected piezoelectric data are typically calculated from phenomenological constants derived from data on ceramic PZT. In this work, the dependence of e31,f on c-axis texture fraction, f001, for {001}PZT thin films was measured by growing films with systematically changed f001 using CaF2, MgO, SrTiO3, and Si substrates. An approximately linear increase in e31,f with f001 was observed for compositions up to 43 mol. % Zr, and 100% c-domain properties were extrapolated. It was demonstrated that c-axis PZT films can achieve e31,f exceeding -12 C/m2 for many tetragonal compositions. The energy harvesting figure of merit, e31,f2/ɛr, for c-axis PZT films surpassed 0.8 C2/m4. This is larger than the figure of merit of gradient-free PZT films grown on Si substrates by a factor of four.

Electric and magnetic properties of oxidic titanium bronzes of rare earths Lnsub(2/3+x)TiOsub(3+-y) with perovskite structure

International Nuclear Information System (INIS)

Bazuev, G.V.; Makarova, O.V.; Shvejkin, G.P.

1983-01-01

A study was made on electric and magnetic properties of oxidic titanium bronzes of rare earths and their dependence on rare earth nature and the degree of rare earth sublattice filling was followed. Data on Lnsub(2/3)TiOsub(3-y) (Ln-Ce, Nd) anion-deficient perovskites are given as well. Investigated Cesub(2/3)TiOsub(2.985) and Ndsub(2/3)TiOsub(2.875) phases as well as defectless with respect to oxygen Lnsub(2/3)TiOsub(3) phases have rhombic structure of perovskite type with ordered position of Ln 3 + cations and vacancies. Specific electric resistance and thermoelectromotive force factor were determined in vacuum at 290-1173 K for samples in the form of parallelepiped of 3x5x25 mm 3 size. Magnetic susceptibility chi was determined at 77-300 K by Faraday method using a device based on magnetic balancewith electromagnetic compensation. Relative error during chi measuring didn't exceed +-2%. Collectivized behaviour of d-electrons of Ti 3 + cations in oxidic titanium bronzes of rare earths: Lnsub(2/3+x)TiOsub(3+-y) (Ln-La, Ce, Nd; 0 < x < 1/3), conditioned by formation of narrow, partly filled π*-zone, was established on the basis of measuring specific electric resistance and magnetic susceptibility

Charge-density-wave partial gap opening in quasi-2D KMo 6O 17 purple bronze studied by angle resolved photoemission spectroscopy

Science.gov (United States)

Valbuena, M. A.; Avila, J.; Pantin, V.; Drouard, S.; Guyot, H.; Asensio, M. C.

2006-05-01

Low dimensional (LD) metallic oxides have been a subject of continuous interest in the last two decades, mainly due to the electronic instabilities that they present at low temperatures. In particular, charge density waves (CDW) instabilities associated with a strong electron-phonon interaction have been found in Molybdenum metallic oxides such as KMo 6O 17 purple bronze. We report an angle resolved photoemission (ARPES) study from room temperature (RT) to T ˜40 K well below the Peierls transition temperature for this material, with CDW transition temperature TCDW ˜120 K. We have focused on photoemission spectra along ΓM high symmetry direction as well as photoemission measurements were taken as a function of temperature at one representative kF point in the Brillouin zone in order to look for the characteristic gap opening after the phase transition. We found out a pseudogap opening and a decrease in the density of states near the Fermi energy, EF, consistent with the partial removal of the nested portions of the Fermi surface (FS) at temperature below the CDW transition. In order to elucidate possible Fermi liquid (FL) or non-Fermi liquid (NFL) behaviour we have compared the ARPES data with that one reported on quasi-1D K 0.3MoO 3 blue bronze.

Combining X-ray based methods to study the protohistoric bronze technology in Western Iberia

International Nuclear Information System (INIS)

Valério, P.; Silva, R.J.C.; Soares, A.M.M.; Araújo, M.F.; Gonçalves, A.P.; Soares, R.M.

2015-01-01

The Phoenician arrival at Iberian coastal regions had an actual influence on indigenous technology. A collection of coeval metallurgical remains and artefacts was studied by EDXRF, micro-EDXRF, SEM–EDS and XRD, to identify certain features of the production and utilisation of metal in protohistoric Western Iberia. The composition of artefacts indicates a prevalence of Cu–Sn alloys with low content of impurities (Pb, As, Sb and Fe) during Late Bronze and Early Iron Ages, while the composition of slags points to a smaller loss of copper in Phoenician smelting operations. Moreover, the amount of iron impurities in metal proved to be a helpful discriminator between indigenous and Phoenician-based metallurgies, showing that later alloys have higher amounts of iron. Besides, the indigenous alloys have higher tin contents that can probably be explained by the easier access to metal sources of local communities

Combining X-ray based methods to study the protohistoric bronze technology in Western Iberia

Energy Technology Data Exchange (ETDEWEB)

Valério, P., E-mail: pvalerio@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS (Portugal); Silva, R.J.C., E-mail: rjcs@fct.unl.pt [CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Monte de Caparica (Portugal); Soares, A.M.M., E-mail: amsoares@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS (Portugal); Araújo, M.F., E-mail: faraujo@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS (Portugal); Gonçalves, A.P., E-mail: apg@ctn.ist.utl.pt [Centro de Ciências e Tecnologias Nucleares (C2TN), Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS (Portugal); Soares, R.M., E-mail: ruigusmao@hotmail.com [UNIARQ, Centro de Arqueologia da Universidade de Lisboa, Faculdade de Letras, Alameda da Universidade, 1600-214 Lisboa (Portugal)

2015-09-01

The Phoenician arrival at Iberian coastal regions had an actual influence on indigenous technology. A collection of coeval metallurgical remains and artefacts was studied by EDXRF, micro-EDXRF, SEM–EDS and XRD, to identify certain features of the production and utilisation of metal in protohistoric Western Iberia. The composition of artefacts indicates a prevalence of Cu–Sn alloys with low content of impurities (Pb, As, Sb and Fe) during Late Bronze and Early Iron Ages, while the composition of slags points to a smaller loss of copper in Phoenician smelting operations. Moreover, the amount of iron impurities in metal proved to be a helpful discriminator between indigenous and Phoenician-based metallurgies, showing that later alloys have higher amounts of iron. Besides, the indigenous alloys have higher tin contents that can probably be explained by the easier access to metal sources of local communities.

Evolution of tetragonal phase of ZrO2 in the corrosion of Zry-4 and Zr-2.5Nb at high pressure and temperature

International Nuclear Information System (INIS)

Bordoni, Roberto A.; Olmedo, Ana M.; Villegas, Marina; Maroto, Alberto J. G.; Lin, J.; Szpunar, J. A.

1999-01-01

The corrosion kinetics of Zr-2.5 Nb and Zircaloy-4 was studied at 350 C degrees in lithiated heavy water. The oxides grown on both alloys during the exposures were found to be strongly textured. The pole figures showed that the major orientation components of the oxide formed on Zr-2.5 Nb were (10-3) [0-10] and (10-3)[301] while (10-3) fiber was formed on Zircaloy-4. No significant change in texture was found in either alloy when increasing the thickness of the oxide film. The phases present in the film were determined and their evolution with the exposure time was followed. The results indicated that the tetragonal volume fraction decreased with increasing the thickness of the oxide layers of both materials. The tetragonal volume fraction of Zircaloy-4 was higher than that of Zr-2.5 Nb for the same oxide thickness. (author)

Retention at room temperature of the tetragonal t''-form in Sc{sub 2}O{sub 3}-doped ZrO{sub 2} nanopowders

Energy Technology Data Exchange (ETDEWEB)

Abdala, Paula M., E-mail: pabdala@citefa.gov.a [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Lamas, Diego G. [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Fantini, Marcia C.A.; Craievich, Aldo F. [Instituto de Fisica, FAP, USP, Travessa R da Rua do Matao, No. 187, Cidade Universitaria, 05508-900 Sao Paulo (Brazil)

2010-04-16

Synchrotron X-ray powder diffraction was applied to the study of the effect of crystallite size on the crystal structure of ZrO{sub 2}-10 mol% Sc{sub 2}O{sub 3} nanopowders synthesized by a nitrate-lysine gel-combustion route. Nanopowders with different average crystallite sizes were obtained by calcination at several temperatures, ranging from 650 to 1200 {sup o}C. The metastable t''-form of the tetragonal phase, exhibiting a cubic unit cell and tetragonal P4{sub 2}/nmc spatial symmetry, was retained at room temperature in fine nanocrystalline powders, completely avoiding the presence of the stable rhombohedral {beta} phase. Differently, this phase was identified in samples calcined at high temperatures and its content increased with increasing crystallite size. The critical maximum crystallite size for the retention of the mestastable t''-form resulted of about 35 nm.

Defect model of a tetragonal Sm sup 3 sup + center found from EPR measurements in CaF sub 2 and SrF sub 2 crystals

CERN Document Server

Zheng Wen Chen; Wu Shao Yi; Tang Sheng

2003-01-01

The EPR parameters (g factors g sub p sub a sub r sub a sub l sub l sub e sub l , g sub p sub e sub r sub p sub e sub n sub d sub i sub c sub u sub l sub a sub r sub t sub o and hyperfine structure constants A sub p sub a sub r sub a sub l sub l sub e sub l , A sub p sub e sub r sub p sub e sub n sub d sub i sub c sub u sub l sub a sub r sub t sub o) of a tetragonal (C sub 4 sub v) Sm sup 3 sup + center in CaF sub 2 and SrF sub 2 crystals are calculated by considering the crystal-field J-mixing among the ground sup 6 H sub 5 sub / sub 2 , the first excited sup 6 H sub 7 sub / sub 2 and second excited sup 6 H sub 9 sub / sub 2 state multiplets. In the calculations the free-ion and crystal-field parameters of the tetragonal Sm sup 3 sup + -F sup - center obtained from polarized laser-selective excitation spectroscopy are used. The calculated results suggest that the tetragonal Sm sup 3 sup + -F sup - center is the Sm sup 3 sup + center found by later EPR measurements. The g factors g sub p sub a sub r sub a sub...

Gold and gold working in Late Bronze Age Northern Greece

Science.gov (United States)

Vavelidis, M.; Andreou, S.

2008-04-01

Numerous objects of gold displaying an impressive variety of types and manufacturing techniques are known from the Late Bronze Age (LBA) contexts of Mycenaean Greece, but very little is known about the origin and processing of gold during the second millennium b.c. Ancient literature and recent research indicate that northern Greece is probably the richest gold-bearing region in Greece, and yet, very little evidence exists regarding the exploitation of its deposits and the production as well as use of gold in the area during prehistory. The unusual find of a group of small stone crucibles at the prehistoric settlement of Thessaloniki Toumba, one with visible traces of gold melting, proves local production and offers a rare opportunity to examine the process of on-site gold working. Furthermore, the comparison of the chemical composition of prehistoric artefacts from two settlements with those of gold deposits in their immediate areas supports the local extraction of gold and opens up the prospect for some of the Mycenaean gold to have originated in northern Greece. The scarcity of gold items in northern Greek LBA contexts may not represent the actual amount of gold produced and consumed, but could be a result of the local social attitudes towards the circulation and deposition of artefacts from precious metals.

Protocol of thermal treatments for the recovery of tetragonal phase in infrastructures of dental prostheses base of ZrO_2 (3-Y_2O_3) mills in CAD / CAM systems or panthories

International Nuclear Information System (INIS)

Simba, B.G.; Ferreira, B.; Santos, C.

2011-01-01

ZrO_2(3%Y_2O_3) bioceramics are used as dental materials mainly as prosthesis components, because present high mechanical properties and translucence. The use of CAD/CAM machining technique needs final grinding which promotes tetragonal monoclinic transformation reducing the reliability of this ceramic. In this work, ZrO_2(3%Y_2O_3) ceramics were sintered at 1450-0h, 1530-2h or 1600-4h and characterized. Different heat-treatment (400-1200 deg C) are proposed aiming the recuperation of the tetragonal crystalline phase. (author)

Wear behavior of tetragonal zirconia polycrystal versus titanium and titanium alloy

International Nuclear Information System (INIS)

Kanbara, Tsunemichi; Yajima, Yasutomo; Yoshinari, Masao

2011-01-01

The aim of this study was to clarify the influence of tetragonal zirconia polycrystal (TZP) on the two-body wear behavior of titanium (Ti). Two-body wear tests were performed using TZP, two grades of cp-Ti or Ti alloy in distilled water, and the cross-sectional area of worn surfaces was measured to evaluate the wear behavior. In addition, the surface hardness and coefficient of friction were determined and an electron probe microanalysis performed to investigate the underlying mechanism of wear. The hardness of TZP was much greater than that of Ti. The coefficient of friction between Ti and Ti showed a higher value than the Ti/TZP combination. Ti was more susceptible to wear by both TZP and Ti than TZP, indicating that the mechanism of wear between TZP and Ti was abrasive wear, whereas that between Ti and Ti was adhesive wear. No remarkable difference in the amount of wear in Ti was observed between TZP and Ti as the opposite material, despite the hardness value of Ti being much smaller than that of TZP. (communication)

Ar-ion etching effects on the XPS spectra of the ferroelectric potassium lithium niobate crystal

International Nuclear Information System (INIS)

Jun, Byeong-Eog; Kim, Chung-Sik; Kim, Hyung-Kook; Kim, Jung-Nam; Hwang, Yoon-Hwae; Chae, Jong-Suk

2005-01-01

Ar + -ion-sputtered surface of KLN crystal was studied by X-ray photoelectron spectroscopy in order to investigate the oxidation states and chemical environments of K, Li, Nb and O ions. As Ar + -sputtering time increased, the decreasing binding energy of Nb 3d and the peak broadening of mixed Nb 4s and Li 1s (namely Nb* 4s) levels were observed. Also, the binding-energy difference between O 1s and Nb* 4s increased as Ar + -ion-sputtering time increased. The broad peak of Nb* 4s was considered to be related to the site occupancy of Li ion in A1 and C in tetragonal tungsten-bronze structure.

Effect of phase morphologies on the mechanical properties of babbitt-bronze composite interfaces

Science.gov (United States)

Liaw, P. K.; Gungor, M. N.; Logsdon, W. A.; Ijiri, Y.; Taszarek, B. J.; Frohlich, S.

1990-02-01

Interfaces of two different babbitt-bronze composites were tested ultrasonically and then were fractured using the Chalmers test method. The primary distinction between the two composites was in the copper content. Use of less copper in the babbitt resulted in interfaces with higher strength, lower ductility, less cracking, and less unbonded area. The differences appeared to stem from the structure of the intermetallic compounds found at the interface, namely, the Cu3Sn and the Cu6Sn5 layers. The low-copper composite failed within a thick, dendrite-like Cu6Sn5 layer, while the high-copper one separated at the interface between a smooth Cu6Sn5 layer and the babbitt metal. The rough interface morphology seemed responsible for the low-copper composite’s increased strength. The correlation between mechanical and ultrasonic properties was poor for the low-copper composite but excellent for the high-copper one. These results suggest that interface morphology can significantly affect mechanical as well as ultrasonic properties.

Computed tomography of a medium size Roman bronze statue of Cupid

Science.gov (United States)

Bettuzzi, M.; Casali, F.; Morigi, M. P.; Brancaccio, R.; Carson, D.; Chiari, G.; Maish, J.

2015-03-01

Diagnostics based on X-ray computed tomography (CT) are becoming increasingly important, not only in the medical field but in industry and cultural heritage. CT devices typical for medical applications, however, can seldom be used on art objects because both they are not easily transportable and they often present high X-ray absorption. It is therefore necessary to make use of portable instrumentation and/or to develop tomographic systems optimized to the characteristics of the objects under examination. This work describes the computed tomography of a first century A.D. Roman bronze statue of Cupid (96.AB.53) in the collection of the J. Paul Getty Museum, within the collaborative framework between the Getty Conservation Institute and the Department of Physics and Astronomy (DIFA) of the University of Bologna (Italy). The tomography performed at the Getty facilities employed a 450 kV X-ray tube and a detection system developed at DIFA. The study highlighted the casting and construction techniques used by Roman foundry workers and provided information on the status of conservation of the statue. A 3D virtual reconstruction allowed the user to define different cross-sections enabling the study of the internal features.

Fabricating Superior NiAl Bronze Components through Wire Arc Additive Manufacturing

Directory of Open Access Journals (Sweden)

Donghong Ding

2016-08-01

Full Text Available Cast nickel aluminum bronze (NAB alloy is widely used for large engineering components in marine applications due to its excellent mechanical properties and corrosion resistance. Casting porosity, as well as coarse microstructure, however, are accompanied by a decrease in mechanical properties of cast NAB components. Although heat treatment, friction stir processing, and fusion welding were implemented to eliminate porosity, improve mechanical properties, and refine the microstructure of as-cast metal, their applications are limited to either surface modification or component repair. Instead of traditional casting techniques, this study focuses on developing NAB components using recently expanded wire arc additive manufacturing (WAAM. Consumable welding wire is melted and deposited layer-by-layer on substrates producing near-net shaped NAB components. Additively-manufactured NAB components without post-processing are fully dense, and exhibit fine microstructure, as well as comparable mechanical properties, to as-cast NAB alloy. The effects of heat input from the welding process and post-weld-heat-treatment (PWHT are shown to give uniform NAB alloys with superior mechanical properties revealing potential marine applications of the WAAM technique in NAB production.

Characterization of a Diamond Ground Y-TZP and Reversion of the Tetragonal to Monoclinic Transformation.

Science.gov (United States)

Candido, L M; Fais, Lmg; Ferreira, E B; Antonio, S G; Pinelli, Lap

To characterize the surface of an yttria-stabilized zirconia (Y-TZP) ceramic after diamond grinding in terms of its crystalline phase, morphology, mean roughness (Ra), and wettability as well as to determine a thermal treatment to reverse the resulting tetragonal to monoclinic (t-m) transformation. Y-TZP specimens were distributed into different groups according to the actions (or no action) of grinding and irrigation. Grinding was accomplished using a diamond stone at a low speed. The samples were characterized by x-ray diffraction (XRD), scanning electron microscopy, goniometry, and profilometry. In situ high-temperature XRD was used to determine an annealing temperature to reverse the t-m transformation. Ra was submitted to the Kruskal-Wallis test, followed by the Dunn test (α=0.05). The volume fraction of the monoclinic phase and contact angle were submitted to one-way analysis of variance, followed by the Tukey test (α=0.05). Monoclinic zirconia was observed on the surface of samples after dry and wet grinding with a diamond stone. The volume fraction of the monoclinic phase was smaller on the dry ground samples (3.6%±0.3%) than on the wet ground samples (5.6%±0.3%). High-temperature XRD showed reversion of the t-m phase transformation, which started at 700°C and completed at 800°C in a conventional oven. Grinding with a diamond stone partially transformed the crystalline phase on the surface of a Y-TZP ceramic from tetragonal to monoclinic zirconia while simultaneously increasing the surface roughness and wettability. The t-m transformation could be reversed by heat treatment at 800°C or 900°C for 60 minutes or 1000°C for 30 minutes.

Stable tetragonal phase and magnetic properties of Fe-doped HfO2 nanoparticles

Science.gov (United States)

Sales, T. S. N.; Cavalcante, F. H. M.; Bosch-Santos, B.; Pereira, L. F. D.; Cabrera-Pasca, G. A.; Freitas, R. S.; Saxena, R. N.; Carbonari, A. W.

2017-05-01

In this paper, the effect in structural and magnetic properties of iron doping with concentration of 20% in hafnium dioxide (HfO2) nanoparticles is investigated. HfO2 is a wide band gap oxide with great potential to be used as high-permittivity gate dielectrics, which can be improved by doping. Nanoparticle samples were prepared by sol-gel chemical method and had their structure, morphology, and magnetic properties, respectively, investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) with electron back scattering diffraction (EBSD), and magnetization measurements. TEM and SEM results show size distribution of particles in the range from 30 nm to 40 nm with small dispersion. Magnetization measurements show the blocking temperature at around 90 K with a strong paramagnetic contribution. XRD results show a major tetragonal phase (94%).

Stable tetragonal phase and magnetic properties of Fe-doped HfO2 nanoparticles

Directory of Open Access Journals (Sweden)

T. S. N. Sales

2017-05-01

Full Text Available In this paper, the effect in structural and magnetic properties of iron doping with concentration of 20% in hafnium dioxide (HfO2 nanoparticles is investigated. HfO2 is a wide band gap oxide with great potential to be used as high-permittivity gate dielectrics, which can be improved by doping. Nanoparticle samples were prepared by sol-gel chemical method and had their structure, morphology, and magnetic properties, respectively, investigated by X-ray diffraction (XRD, transmission electron microscopy (TEM and scanning electron microscopy (SEM with electron back scattering diffraction (EBSD, and magnetization measurements. TEM and SEM results show size distribution of particles in the range from 30 nm to 40 nm with small dispersion. Magnetization measurements show the blocking temperature at around 90 K with a strong paramagnetic contribution. XRD results show a major tetragonal phase (94%.

Adaptive ferroelectric state at morphotropic phase boundary: Coexisting tetragonal and rhombohedral phases

International Nuclear Information System (INIS)

Zhang, Yang; Xue, Dezhen; Wu, Haijun; Ding, Xiangdong; Lookman, Turab; Ren, Xiaobing

2014-01-01

With a focus on local symmetry, the microstructural basis for high piezoelectric performance in PbMg 1/3 Nb 2/3 O 3 –xPbTiO 3 (PMN–PT) ceramics at the morphotropic phase boundary (MPB) composition was investigated by means of convergent-beam electron diffraction analysis and twin diffraction pattern analysis. The local structure was found to consist of coexisting (1 0 1)-type tetragonal nanotwins and (0 0 1)-type rhombohedral nanotwins. A phenomenological theory based on crystallography is proposed to show that such nanoscale coexistence can give rise to an average monoclinic structure through strain accommodation. The average monoclinic structures (Ma and Mc) vary with temperature and composition due to the dependence on temperature and composition of the lattice parameters. Based on in situ X-ray diffraction data, we demonstrate how the polarization rotates across the MPB region in PMN–PT ceramics with varying temperatures and compositions

Micro-chemical and micro-structural investigation of archaeological bronze weapons from the Ayanis fortress (lake Van, Eastern Anatolia, Turkey)

Science.gov (United States)

Faraldi, F.; Çilingirǒglu, A.; Angelini, E.; Riccucci, C.; De Caro, T.; Batmaz, A.; Mezzi, A.; Caschera, D.; Cortese, B.

2013-12-01

Bronze weapons (VII cen BC) found during the archaeological excavation of the Ayanis fortress (lake Van, eastern Anatolia, Turkey) are investigated in order to determine their chemical composition and metallurgical features as well as to identify the micro-chemical and micro-structural nature of the corrosion products grown during long-term burial. Small fragments were sampled from the artefacts and analysed by means of the combined use of optical microscopy (OM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results show that the bronze artefacts have been manufactured by using alloys with a controlled and refined chemical composition demonstrating the high level metallurgical competence and skill of the Urartian craftsmen and artists. Furthermore, the micro-structural and metallurgical investigations evidence the presence of equiaxed grains in the matrix, indicating that the artefact were produced by repeated cycles of mechanical shaping and thermal annealing treatments to restore the alloy ductility. From the degradation point of view, the results show the structures and the chemical composition of the stratified corrosion layers (i.e. the patina) where the copper or tin depletion phenomenon is commonly observed with the surface enrichment of some elements coming from the burial soil, mainly Cl, which is related to the high concentration of chlorides in the Ayanis soil. The results reveal also that another source of degradation is the inter-granular corrosion phenomenon likely increased by the metallurgical features of the alloys caused by the high temperature manufacturing process that induces crystallisation and segregation phenomena along the grain boundaries.

Combined mode I-mode II fracture of 12-mol%-ceria-doped tetragonal zirconia polycrystalline ceramic

International Nuclear Information System (INIS)

Tikare, V.; Choi, S.R.

1997-01-01

The mode I, mode II, and combined mode I-mode II fracture behavior of ceria-doped tetragonal zirconia polycrystalline (Ce-TZP) ceramic was studied. The single-edge-precracked-beam (SEPB) samples were fractured using the asymmetric four-point-bend geometry. The ratio of mode I to mode II loading was varied by varying the degree of asymmetry in the four-point-bend geometry. The minimum strain energy density theory best described the mixed-mode fracture behavior of Ce-TZP with the mode I fracture toughness, K IC = 8.2 ± 0.6 MPa·m 1/2 , and the mode II fracture toughness, K IIC = 8.6 ± 1.3 MPa·m 1/2

Collapsed tetragonal phase as a strongly covalent and fully nonmagnetic state: Persistent magnetism with interlayer As-As bond formation in Rh-doped Ca0 .8Sr0 .2Fe2As2

Science.gov (United States)

Zhao, K.; Glasbrenner, J. K.; Gretarsson, H.; Schmitz, D.; Bednarcik, J.; Etter, M.; Sun, J. P.; Manna, R. S.; Al-Zein, A.; Lafuerza, S.; Scherer, W.; Cheng, J. G.; Gegenwart, P.

2018-02-01

A well-known feature of the CaFe2As2 -based superconductors is the pressure-induced collapsed tetragonal phase that is commonly ascribed to the formation of an interlayer As-As bond. Using detailed x-ray scattering and spectroscopy, we find that Rh-doped Ca0.8Sr0.2Fe2As2 does not undergo a first-order phase transition and that local Fe moments persist despite the formation of interlayer As-As bonds. Our density functional theory calculations reveal that the Fe-As bond geometry is critical for stabilizing magnetism and the pressure-induced drop in the c lattice parameter observed in pure CaFe2As2 is mostly due to a constriction within the FeAs planes. The collapsed tetragonal phase emerges when covalent bonding of strongly hybridized Fe 3 d and As 4 p states completely wins out over their exchange splitting. Thus the collapsed tetragonal phase is properly understood as a strong covalent phase that is fully nonmagnetic with the As-As bond forming as a by-product.

Pressure dependence of the Peierls transition in the quasi two-dimensional purple bronze KMo 6O 17

Science.gov (United States)

Rötger, A.; Beille, J.; Laurant, J. M.; Schlenker, C.

1993-09-01

The electrical resistivity and the lattice parameters have been studied as a function of pressure on the quasi-twodimensional purple bronze KMo 6O 17 which shows a Peierls transition towards a commensurate charge density wave state. The Peierls temperature is found to be first slightly decreased for pressures smaller than 6 kbar, then strongly increased above. This increase is associated to an anomalous contraction of the lattice parameters in the plane of the layers. The corresponding large increase of the compressibility above 16 kbar at 300 K is associated to the pretransitional regime of the Peierls transition as a function of pressure. These results are attributed mainly to an improved nesting of the Fermi surface under pressure.

Estudo do comportamento da resina base na formulação de compósitos de politetrafluoretileno com bronze

OpenAIRE

Ronaldo Euzébio Bento

2011-01-01

Resumo: Esse trabalho concentra os estudos na investigação das propriedades de resistência a tração e alongamento do compósito de Politetrafluoretileno (PTFE) com 60% de bronze após a substituição do tipo de PTFE utilizado na formulação desse compósito. Atualmente esse compósito utiliza PTFE convencional na formulação e o objetivo é alterar para PTFE modificado. A motivação para essa alteração deveu-se ao fato que o PTFE convencional apresenta disponibilidade limitada dificultando o desenvolv...

Emission of organic compounds from mould and core binders used for casting iron, aluminium and bronze in sand moulds

DEFF Research Database (Denmark)

Tiedje, Niels Skat; Crepaz, Rudolf; Eggert, Torben

2010-01-01

compositions were tested. A test method that provides uniform test conditions is described. The method can be used as general test method to analyse off gasses from binders. Moulds containing a standard size casting were produced and the amount and type of organic compounds resulting from thermal degradation...... of binders was monitored when cast iron, bronze and aluminium was poured in the moulds. Binder degradation was measured by collecting off gasses in a specially designed ventilation hood at a constant flow rate. Samples were taken from the ventilation system and analysed for hydrocarbons and CO content...

Flux pinning in bronze-processed Nb3Sn wires

International Nuclear Information System (INIS)

Suenaga, M.; Welch, D.O.

1980-01-01

The scaling law derived by Kramer for magnetic flux pinning in high magnetic fields was examined for its applicability to the magnetic field dependence of critical-current densities in the bronze processed monofilamentary Nb 3 Sn wires. From this it was concluded that: (1) its prediction for the form of the dependence of critical current on magnetic field and grain size [/J vector /sub c/ x H vector/ approx. h/sup 1/2/(1-h) 2 (1-a 0 √rho) -2 ] was found to be very good in most cases including wires with very small Nb 3 Sn grains (approx. 400 A). It was found very useful in comparison of J/sub c/ for different wires and in extrapolating to obtain H/sub c2/ for these wires. (2) However, it could not account consistently for the anisotropy in critical current of a tape which was measured with H applied perpendicular and parallel to the tape face. (3) The values of kappa 1 which were determined with the scaling law were too small by a factor of 2 to 3, and the trend in the variation with heat-treating time was opposite to that which is reasonably to be expected. That the behavior of kappa 1 is thus seriously in contradiction with the expected behavior for Nb 3 Sn suggests basic faults in the derivation of the scaling equation for critical currents at high magnetic fields

Protocol of thermal treatments for the recovery of tetragonal phase in infrastructures of dental prostheses base of ZrO{sub 2} (3-Y{sub 2}O{sub 3}) mills in CAD / CAM systems or panthories; Protocolo de tratamentos termicos visando recuperacao da fase tetragonal em infraestruturas de proteses dentarias a base de ZrO{sub 2}(3-Y{sub 2}O{sub 3}) fresadas em sistemas CAD/CAM ou pantografos

Energy Technology Data Exchange (ETDEWEB)

Simba, B.G.; Ferreira, B.; Santos, C. [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia; Costa, L. [Centro Universitario de Volta Redonda (MeMAT/UNIFOA), RJ (Brazil). Pro-Reitoria de Pesquisa e Extensao; Sa, L.F.C. de, E-mail: brgalvao@yahoo.com.br [PROTMAT Materiais Avancados, Volta Redonda, RJ (Brazil)

2011-07-01

ZrO{sub 2}(3%Y{sub 2}O{sub 3}) bioceramics are used as dental materials mainly as prosthesis components, because present high mechanical properties and translucence. The use of CAD/CAM machining technique needs final grinding which promotes tetragonal monoclinic transformation reducing the reliability of this ceramic. In this work, ZrO{sub 2}(3%Y{sub 2}O{sub 3}) ceramics were sintered at 1450-0h, 1530-2h or 1600-4h and characterized. Different heat-treatment (400-1200 deg C) are proposed aiming the recuperation of the tetragonal crystalline phase. (author)

Comparative study on cubic and tetragonal CexZr1-xO2 supported MoO3-catalysts for sulfur-resistant methanation

Science.gov (United States)

Liu, Zhaopeng; Xu, Yan; Cheng, Jiaming; Wang, Weihan; Wang, Baowei; Li, Zhenhua; Ma, Xinbin

2018-03-01

In this paper, two kinds of CexZr1-xO2 solid solution carriers with different Ce/Zr ratio were prepared by one-step co-precipitation method: the cubic Ce0.8Zr0.2O2 and the tetragonal Ce0.2Zr0.8O2 support. The MoO3/Ce0.8Zr0.2O2 and MoO3/Ce0.2Zr0.8O2 catalysts were prepared by incipient wetness impregnation method for comparative study on sulfur-resistant methanation reaction. The N2 adsorption/desorption, X-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron (XPS), transmission electron microscopy (TEM), temperature-programmed reduction by hydrogen (H2-TPR) were undertaken to characterize the physico-chemical properties of the samples. The results indicated that the prepared MoO3/CexZr1-xO2 catalysts have a mesoporous structure with high surface area and uniform pore size distribution, achieving good MoO3 dispersion on CexZr1-xO2 supports. As for the catalytic performance of sulfur-resistant methanation, the cubic MoO3/Ce0.8Zr0.2O2 exhibited better than the tetragonal MoO3/Ce0.2Zr0.8O2 catalyst at reaction temperature 400 °C and 450 °C. CO conversion on the cubic MoO3/Ce0.8Zr0.2O2 catalyst was 50.1% at 400 °C and 75.5% at 450 °C, which is respectively 7% and 20% higher than that on the tetragonal MoO3/Ce0.2Zr0.8O2 catalyst. These were mainly attributed to higher content of active MoS2 on the surface of catalyst, the enhanced oxygen mobility, increased Mo-species dispersion as well as the excellent reducibility resulted from the increased amount of the reducible Ce3+ on the cubic MoO3/Ce0.8Zr0.2O2 catalyst.

Pressure effect on structural, elastic, and thermodynamic properties of tetragonal B4C4

Directory of Open Access Journals (Sweden)

Baobing Zheng

2015-03-01

Full Text Available The compressibility, elastic anisotropy, and thermodynamic properties of the recently proposed tetragonal B4C4 (t-B4C4 are investigated under high temperature and high pressure by using of first-principles calculations method. The elastic constants, bulk modulus, shear modulus, Young’s modulus, Vickers hardness, Pugh’s modulus ratio, and Poisson’s ratio for t-B4C4 under various pressures are systematically explored, the obtained results indicate that t-B4C4 is a stiffer material. The elastic anisotropies of t-B4C4 are discussed in detail under pressure from 0 GPa to 100 GPa. The thermodynamic properties of t-B4C4, such as Debye temperature, heat capacity, and thermal expansion coefficient are investigated by the quasi-harmonic Debye model.

Ligand mediated synthesis of AgInSe2 nanoparticles with tetragonal/orthorhombic crystal phases

International Nuclear Information System (INIS)

Abazović, Nadica D.; Čomor, Mirjana I.; Mitrić, Miodrag N.; Piscopiello, Emanuela; Radetić, Tamara; Janković, Ivana A.; Nedeljković, Jovan M.

2012-01-01

Nanosized AgInSe 2 particles (d ∼ 7–25 nm) were synthesized using colloidal chemistry method at 270 °C. As solvents/surface ligands 1-octadecene, trioctylphosphine, and oleylamine were used. It was shown that choice of ligand has crucial impact not only on final crystal phase of nanoparticles, but also at mechanism of crystal growth. X-ray diffraction and TEM/HRTEM techniques were used to identify obtained crystal phases and to measure average size and shape of nanoparticles. UV/Vis data were used to estimate band-gap energies of obtained samples. It was shown that presented routes can provide synthesis of nanoparticles with desired crystal phase (tetragonal and/or orthorhombic), with band-gap energies in the range from 1.25 to 1.53 eV.

Structure of tetragonal martensite in the In95.42Cd4.58 cast alloy

Science.gov (United States)

Khlebnikova, Yu. V.; Egorova, L. Yu.; Rodionov, D. P.; Kazantsev, V. A.

2017-11-01

The structure of martensite in the In95.42Cd4.58 alloy has been studied by metallography, X-ray diffraction, dilatometry, and transmission electron microscopy. It has been shown that a massive structure built of colonies of tetragonal lamellar plates divided by a twin boundary {101}FCT is formed in the alloy under cooling below the martensite FCC → FCT transition temperature. The alloy recrystallizes after a cycle of FCT → FCC → FCT transitions with a decrease in the grain size by several times compared with the initial structure such fashion that the size of massifs and individual martensite lamella in the massif correlates with the change in the size of the alloy grain. Using thermal cycling, it has been revealed that the alloy tends to stabilize the high-temperature phase.

Electric and magnetic properties of oxidic titanium bronzes of rare earths Lnsub(2/3+x)TiOsub(3+-y) with perovskite structure

Energy Technology Data Exchange (ETDEWEB)

Bazuev, G V; Makarova, O V; Shvejkin, G P [AN SSSR, Sverdlovsk. Inst. Khimii

1983-01-01

A study was made on electric and magnetic properties of oxidic titanium bronzes of rare earths and their dependence on rare earth nature and the degree of rare earth sublattice filling was followed. Data on Lnsub(2/3)TiOsub(3-y) (Ln-Ce, Nd) anion-deficient perovskites are given as well. Investigated Cesub(2/3)TiOsub(2.985) and Ndsub(2/3)TiOsub(2.875) phases as well as defectless with respect to oxygen Lnsub(2/3)TiOsub(3) phases have rhombic structure of perovskite type with ordered position of Ln/sup 3 +/ cations and vacancies. Specific electric resistance and thermoelectromotive force factor were determined in vacuum at 290-1173 K for samples in the form of parallelepiped of 3x5x25 mm/sup 3/ size. Magnetic susceptibility chi was determined at 77-300 K by Faraday method using a device based on magnetic balance with electromagnetic compensation. Relative error during chi measuring didn't exceed +-2%. Collectivized behaviour of d-electrons of Ti/sup 3 +/ cations in oxidic titanium bronzes of rare earths: Lnsub(2/3+x)TiOsub(3+-y) (Ln-La, Ce, Nd; 0 < x < 1/3), conditioned by formation of narrow, partly filled ..pi..*-zone, was established on the basis of measuring specific electric resistance and magnetic susceptibility.

Charge-density-wave partial gap opening in quasi-2D KMo6O17 purple bronze studied by angle resolved photoemission spectroscopy

International Nuclear Information System (INIS)

Valbuena, M.A.; Avila, J.; Pantin, V.; Drouard, S.; Guyot, H.; Asensio, M.C.

2006-01-01

Low dimensional (LD) metallic oxides have been a subject of continuous interest in the last two decades, mainly due to the electronic instabilities that they present at low temperatures. In particular, charge density waves (CDW) instabilities associated with a strong electron-phonon interaction have been found in Molybdenum metallic oxides such as KMo 6 O 17 purple bronze. We report an angle resolved photoemission (ARPES) study from room temperature (RT) to T ∼40 K well below the Peierls transition temperature for this material, with CDW transition temperature T CDW ∼120 K. We have focused on photoemission spectra along ΓM high symmetry direction as well as photoemission measurements were taken as a function of temperature at one representative k F point in the Brillouin zone in order to look for the characteristic gap opening after the phase transition. We found out a pseudogap opening and a decrease in the density of states near the Fermi energy, E F , consistent with the partial removal of the nested portions of the Fermi surface (FS) at temperature below the CDW transition. In order to elucidate possible Fermi liquid (FL) or non-Fermi liquid (NFL) behaviour we have compared the ARPES data with that one reported on quasi-1D K 0.3 MoO 3 blue bronze

Cubic-tetragonal transformation and magnetic properties in copper ferrites with excess Fe/sub 2/O/sub 3/

Energy Technology Data Exchange (ETDEWEB)

Sugimoto, M [Saitama Univ., Urawa (Japan)

1977-01-01

Measurements have been performed of cubic-tetragonal transition temperatures and magnetic properties on a set of those samples of the binary system CuO-Fe/sub 2/O/sub 3/ which contain Fe/sub 2/O/sub 3/ more than stoichiometric CuFe/sub 2/O/sub 4/. A marked magnetic hardening was observed on a sample of 40CuO.60Fe/sub 2/O/sub 3/ which has been verified, through the X-ray analyses and measurements of Moessbauer spectra, to result from the precipitation of ..cap alpha..-Fe/sub 2/O/sub 3/ taking place during annealing.

Generalized One-Band Model Based on Zhang-Rice Singlets for Tetragonal CuO

Science.gov (United States)

Hamad, I. J.; Manuel, L. O.; Aligia, A. A.

2018-04-01

Tetragonal CuO (T-CuO) has attracted attention because of its structure similar to that of the cuprates. It has been recently proposed as a compound whose study can give an end to the long debate about the proper microscopic modeling for cuprates. In this work, we rigorously derive an effective one-band generalized t -J model for T-CuO, based on orthogonalized Zhang-Rice singlets, and make an estimative calculation of its parameters, based on previous ab initio calculations. By means of the self-consistent Born approximation, we then evaluate the spectral function and the quasiparticle dispersion for a single hole doped in antiferromagnetically ordered half filled T-CuO. Our predictions show very good agreement with angle-resolved photoemission spectra and with theoretical multiband results. We conclude that a generalized t -J model remains the minimal Hamiltonian for a correct description of single-hole dynamics in cuprates.

Crystal structure refinements of tetragonal (OH,F)-rich spessartine and henritermierite garnets

Energy Technology Data Exchange (ETDEWEB)

Antao, Sytle M.; Cruickshank, Laura A.

2018-01-30

Cubic garnet (space group Ia\\overline 3 d) has the general formulaX₃Y₂Z₃O₁₂, whereX,YandZare cation sites. In the tetragonal garnet (space groupI4₁/acd), the corresponding cation sites areX1 andX2,Y, andZ1 andZ2. In both space groups only theYsite is the same. The crystal chemistry of a tetragonal (OH,F)-rich spessartine sample from Tongbei, near Yunxiao, Fujian Province, China, with composition^X(Mn_2.82Fe^{2+}_{0.14}Ca_0.04)_Σ3^Y{Al_1.95Fe^{3+}_{0.05}}_Σ2^Z[(SiO₄)_2.61(O₄H₄)_0.28(F₄)_0.11]_Σ3(Sps₉₄Alm₅Grs₁) was studied with single-crystal X-ray diffraction and space groupI4₁/acd. The deviation of the unit-cell parameters from cubic symmetry is small [a= 11.64463(1),c= 11.65481 (2) Å,c/a= 1.0009]. Point analyses and back-scattered electron images, obtained by electron-probe microanalysis, indicate a homogeneous composition. TheZ2 site is fully occupied, but theZ1 site contains vacancies. The occupiedZ1 andZ2 sites with Si atoms are surrounded by four O atoms, as in anhydrous cubic garnets. Pairs of split sites are O1 with F11 and O2 with O22. When theZ1 site is vacant, a larger [(O₂H₂)F₂] tetrahedron is formed by two OH and two F anions in the O22 and F11 sites, respectively. This [(O₂

Effects of Ca-dopant on the pyroelectric, piezoelectric and dielectric properties of (Sr 0.6Ba 0.4) 4Na 2Nb 10O 30 ceramics

KAUST Repository

Yao, Yingbang

2012-12-01

Calcium-doped sodium strontium barium niobate (SBNN, (Sr 0.6Ba 0.4) 4-xCa xNa 2Nb 10O 30, 0 ≤ x ≤ 0.5) ceramics were prepared by a conventional solid-state reaction method. SBNN showed \\'filled\\' tetragonal tungsten-bronze structure with fully occupied A-sites. The tetragonal structure, as revealed by X-ray diffraction (XRD) and Raman spectroscopy, was not affected by the Ca-dopant. Effects of Ca-doping concentration on the phase transitions as well as ferroelectric, piezoelectric and pyroelectric properties of the SBNN ceramics were investigated. From the dielectric studies, two anomalies were observed, namely, a sharp normal ferroelectric transition at 260 °C and a broad maximum at round -110 °C. The later was affected by the Ca-doping concentration and its origin was discussed. At x = 0.3, the sample exhibited the highest pyroelectric coefficient of 168 μC/m 2 K and the largest piezoelectric coefficient (d 33) of 63 pC/N at room temperature. On the basis of our results, the pyroelectric properties of the SBNN were improved by Ca-doping. © 2012 Elsevier B.V. All rights reserved.

Effects of Ca-dopant on the pyroelectric, piezoelectric and dielectric properties of (Sr 0.6Ba 0.4) 4Na 2Nb 10O 30 ceramics

KAUST Repository

Yao, Yingbang; Mak, C. L.

2012-01-01

Calcium-doped sodium strontium barium niobate (SBNN, (Sr 0.6Ba 0.4) 4-xCa xNa 2Nb 10O 30, 0 ≤ x ≤ 0.5) ceramics were prepared by a conventional solid-state reaction method. SBNN showed 'filled' tetragonal tungsten-bronze structure with fully occupied A-sites. The tetragonal structure, as revealed by X-ray diffraction (XRD) and Raman spectroscopy, was not affected by the Ca-dopant. Effects of Ca-doping concentration on the phase transitions as well as ferroelectric, piezoelectric and pyroelectric properties of the SBNN ceramics were investigated. From the dielectric studies, two anomalies were observed, namely, a sharp normal ferroelectric transition at 260 °C and a broad maximum at round -110 °C. The later was affected by the Ca-doping concentration and its origin was discussed. At x = 0.3, the sample exhibited the highest pyroelectric coefficient of 168 μC/m 2 K and the largest piezoelectric coefficient (d 33) of 63 pC/N at room temperature. On the basis of our results, the pyroelectric properties of the SBNN were improved by Ca-doping. © 2012 Elsevier B.V. All rights reserved.

Effect of MnO doping on the structure, microstructure and electrical properties of the (K,Na,Li)(Nb,Ta,Sb)O3 lead-free piezoceramics

International Nuclear Information System (INIS)

Rubio-Marcos, F.; Marchet, P.; Vendrell, X.; Romero, J.J.; Remondiere, F.; Mestres, L.; Fernandez, J.F.

2011-01-01

Highlights: · MnO doping effects on structure and properties of (K,Na,Li)(Nb,Ta,Sb)O 3 piezoceramics. · The structure changes towards an orthorhombic symmetry for higher MnO concentrations. · High doping levels induce a tetragonal tungsten-bronze secondary phase. · Mn 2+ doping modifies the phase transition temperature and the piezoelectric properties. · Manganese doping increases the mechanical quality factor Q m . - Abstract: Mn 2+ -doped (K,Na,Li)(Nb,Ta,Sb)O 3 lead-free piezoelectric ceramics have been prepared by a conventional sintering technique. The effects of Mn 2+ doping on the phase structure, microstructure and ferro-piezoelectric properties of the ceramics have been evaluated. MnO doping modifies the (K,Na,Li)(Nb,Ta,Sb)O 3 structure, giving rise to the appearance of a TTB-like secondary phase and to changes on the orthorhombic to tetragonal phase transition temperature. The modification of this temperature induces a reduction of the piezoelectric constants, which is accompanied by an increase on the mechanical quality factor. Mn 2+ ions incorporate into the perovskite structure in different off ways depending on their concentration.

Tetragonal Lysozyme Interactions Studied by Site Directed Mutagenesis

Science.gov (United States)

Crawford, Lisa; Karr, Laurel J.; Nadarajah, Arunan; Pusey, Marc

1999-01-01

A number of recent experimental and theoretical studies have indicated that tetragonal lysozyme crystal growth proceeds by the addition of aggregates, formed by reversible self association of the solute molecules in the bulk solution. Periodic bond chain and atomic force microscopy studies have indicated that the probable growth unit is at minimum a 43 tetramer, and most likely an octamer composed of two complete turns about the 43 axis. If these results are correct, then there are intermolecular interactions which are only formed in the solution and others only formed at the joining of the growth unit to the crystal surface. We have set out to study these interactions, and the correctness of this hypothesis, using site directed mutagenesis of specific amino acid residues involved in the different bonds. We had initially expressed wild type lysozyme in S. cervasiae with yields of approximately 5 mg/L, which were eventually raised to approximately 40 mg/L. We are now moving the expression to the Pichia system, with anticipated yields of 300 to (3)500 mg/L, comparable to what can be obtained from egg whites. An additional advantage of using recombinant protein is the greater genetic homogeneity of the material obtained and the absence of any other contaminating egg proteins. The first mutation experiments are TYR 23 (Registered) PHE or ALA and ASN 113 (Registered) ALA or ASP. Both TYR 23 and ASN 113 form part of the postulated dimerization intermolecular binding site which lead to the formation of the 43 helix. Tyrosine also participates in an intermolecular hydrogen bond with ARG 114. The results of these and subsequent experiments will be discussed.

Geoarchaeological research on Bronze Age settlement mounds in the Kolkheti lowlands at the Black Sea coast of Georgia

Science.gov (United States)

Laermanns, Hannes; Heisterkamp, Arne; Kirkitadze, Giorgi; Elashvili, Mikheil; Verheul, Jan; Kelterbaum, Daniel; Helmut, Brückner

2016-04-01

0.0.1 Situated between the Rivers Enguri in the north and Khobistsqali in the south, more than 20 settlement mounds (local name Dikhagudzuba), identified by field survey and remote sensing techniques, give evidence of a densely populated landscape in the coastal lowlands of eastern Georgia during the Bronze Age. While the existing chronology of these mounds is based on ceramic evidence obtained during a previous archaeological research, only limited information is available on their internal architecture and their palaeoenvironmental context, and the chronology of the different layers is as yet lacking. 0.0.2 Within the framework of a geoarchaeological research project, we carried out eleven vibracores on and in direct vicinity of three of the most prominent mounds, situated close to the villages of Orulu and Ergeta. Based on these sediment cores, our study aims at (i) establishing a chronostratigraphical framework for the settlements based on radiocarbon dating; (ii) reconstructing possible phases and gaps of occupation; and (iii) identifying the environmental conditions during the time of their existence. Geochemical and sedimentological analyses were carried out to decipher element contents (XRF), granulometry, and organic contents (LOI, C/N) of sediment samples, supporting the interpretation of the mounds' stratigraphical evolution and related human occupation. The three investigated settlement mounds are similar in dimension and stratigraphy, and different settlement layers could be identified in each of them. The 14C age estimates indicate that their formation occurred during the second half of the 3rd and the first half of the 2nd millennium BC, thus confirming the archaeological interpretation of their Bronze Age origin. Based on the granulometric and geochemical data, palaeoenvironmental conditions in the vicinity of the settlements were dominated by fluvial processes.

Surface mechanical property and residual stress of peened nickel-aluminum bronze determined by in-situ X-ray diffraction

Science.gov (United States)

Wang, Chengxi; Jiang, Chuanhai; Zhao, Yuantao; Chen, Ming; Ji, Vincent

2017-10-01

As one of the most important surface strengthening method, shot peening is widely used to improve the fatigue and stress corrosion crack resistance of components by introducing the refined microstructure and compressive residual stress in the surface layer. However, the mechanical properties of this thin layer are different from the base metal and are difficult to be characterized by conventional techniques. In this work, a micro uniaxial tensile tester equipped with in-situ X-ray stress analyzer was employed to make it achievable on a nickel-aluminum bronze with shot peening treatment. According to the equivalent stress-strain relationship based on Von Mises stress criterion, the Young's modulus and yield strength of the peened layer were calculated. The results showed that the Young's modulus was the same as the bulk material, and the yield strength corresponding to the permanent plastic strain of 0.2% was increased by 21% after SP. But the fractographic analysis showed that the fracture feature of the surface layer was likely to transform from the dimple to the cleavage, indicating the improved strength might be attained at the expense of ductility. The monotonic and cyclic loading were also performed via the same combined set-up. In addition, the specific relaxation behavior of compressive residual stress was quantified by linear logarithm relationship between residual stress and cycle numbers. It was found that the compressive residual stress mainly relaxed in the first few cycles, and then reached steady state with further cycles. The relaxation rate and the stable value were chiefly depended on the stress amplitude and number of cycles. The retained residual stress kept in compressive under all given applied stress levels, suggesting that the shot peening could introduce a more stable surface layer of compressive residual stress other than the elevated strength of nickel-aluminum bronze alloy.

Electrochemical zinc insertion into W18O49: Synthesis and characterization of new bronzes

International Nuclear Information System (INIS)

Martinez-de la Cruz, A.; Amador, U.; Rodriguez-Carvajal, J.; Garcia-Alvarado, F.

2005-01-01

Divalent zinc ions have been electrochemically inserted into W 18 O 49 , producing zinc bronzes. Under our experimental conditions, W 18 O 49 accepts zinc reversibly as a guest up to 0.9 ions per formula. The reaction seems to proceed through the formation of a solid solution in which the W-O framework of the parent oxide is maintained. The location of the Zn 2+ ions in the framework of W 18 O 49 has been determined by neutron diffraction on a chemically prepared sample having the composition Zn 0.34 W 18 O 49 . As a main result, we found that Zn prefers to insert in one of the four types of quadrangular tunnels. More precisely, it is displaced from the center to occupy a low coordination site. This result indicates that a significant covalent character exists in the Zn-O bond. - Graphical Abstract: The structure of Zn 0.36 W 18 O 49 projected along the b-axis

Electrochemical fabrication of interconnected tungsten bronze nanosheets for high performance supercapacitor

Science.gov (United States)

Yang, Gan; Liu, Xiao-Xia

2018-04-01

Interconnected H0.12WO3ṡH2O nanosheets with high electrochemical performances are fabricated on partial exfoliated graphite substrate (Ex-GF) by potential-limited pulse galvanostatic method (PLPG). The dead volume problem of bulk pesudocapacitive materials is addressed by the novel interconnected nanosheets structure, enabling a large specific capacitance of 5.95 F cm-2 (495.8 F g-1) at 2 mA cm-2. Merited from the fluent electrolyte penetration channels established by the plenty voids among nanosheets, as well as fast electron transportation in the electronic conductive tungsten bronze which is directly grown from graphite substrate, the obtained WO3/Ex-GF demonstrates excellent rate capability. The material can maintain 60.0% of its capacitance when the discharge current density increases from 2 to 100 mA cm-2. Moreover, WO3/Ex-GF doesn't show capacitance decay after 5000 galvanostatic charge-discharge cycles, displaying its super stability. Furthermore, a high performance asymmetric supercapacitor assembled by using WO3/Ex-GF and electrochemical fabricated MnO2/Ex-GF as negative and positive electrodes, respectively displays a high energy density of 2.88 mWh cm-3 at the power density of 11.1 mW cm-3, demonstrating its potential application for energy storage.

Materials for the study of the bronze age in the valley of the Vinalopo (Alicante | Materiales para el estudio de la Edad del Bronce en el Valle Medio del Vinalopó (Alicante | Materiales para el estudio de la Edad del Bronce en el Valle Medio del Vinalopó (Alicante

Directory of Open Access Journals (Sweden)

Juan Francisco Navarro Mederos

1982-12-01

Full Text Available Se presenta un grupo de poblados del Bronce en el Valle Medio del Vinalopó, provincia de Alicante, y los materiales procedentes de ellos y conservados en colecciones privadas. Su conocimiento permite incluir esta comarca en la cultura del Bronce Valenciano —aunque manteniendo una cierta personalidad— y aventurar hipótesis sobre la dinámica de la Edad del Bronce a lo largo de la cuenca del Vinalopó, sus contactos exteriores, las fronteras con el mundo argárico e intentar ordenarlos cronológicamente en base a un esquema propuesto para la globalidad del Bronce Valenciano. | L'article offre l'étude d'un groupe de sites de l'âge du Bronze dans la vallée du Vinalopó et des matériaux archéologiques conservés dans des collections privées. Des resultats de cet étude on peut inférer l'appartenance de cette zone a la civilisation du Bronze Valenciano, tout en conservant des traits individuants, et aussi tenter d'expliquer la dynamique de l'âge du Bronze au long de la vallée du Vinalopó, ses rapports extérieurs et la frontière avec la civilisation de l'Argar. On donne également une tentative de chronologie fondee sur un schéma global pour le Bronze Valenciano.

Passivation of laser-treated nickel aluminum bronze as measured by electrochemical impedance spectroscopy

International Nuclear Information System (INIS)

Klassen, R.D.; Hyatt, C.V.; Roberge, P.R.

2000-01-01

Electrochemical impedance spectroscopy was used to assess the corrosion behavior of the weld zones and surface conditions of a laser-clad nickel aluminum bronze immersed in a 3.5% neutral saline solution. The zones and conditions examined included: (i) as-cast base material; (ii) laser-clad material with the high temperature oxide from welding intact; (iii) polished laser-clad material and (iv) specimens representative of just the as-deposited and reheated zones of the laser-clad surface. A pseudo steady-state level of passivation was reached in all the samples within 40 hours. The reheated zone passivated more slowly than the as-deposited region and both weld zones passivated more quickly than the base material. Electrochemical impedance data illustrated a transition during the passivation process of the polished specimens that is consistent with the development of a film layer that restricted mass transfer. The welding oxide from the laser treatment immediately behaved as a passivation film that was indistinguishable from that which eventually develops on polished specimens. (author)

Devil's staircase of odd-number charge order modulations in divalent β -vanadium bronzes under pressure

Science.gov (United States)

Yamauchi, Touru; Ueda, Hiroaki; Ohwada, Kenji; Nakao, Hironori; Ueda, Yutaka

2018-03-01

A common characteristic of quasi-one-dimensional (q1D) conductors β -A0.33V2O5 (A = Li, Na, and Ag) is that the charge ordering (CO), the ground state (GS) at ambient pressure, and the superconducting (SC) phases, the GS under high pressure, are competing with each other. We have explored high-pressure properties of divalent β -vanadium bronzes, β -A0.33V2O5 (A = Ca, Sr, and Pb), which are A -cation stoichiometry finely controlled single-crystal/powder samples, and found the absence of the SC phase. In these observations, however, we observed enormous and novel phase transitions, a kind of "devil's staircase"-type phase transitions in the charge ordering (CO) phases. The most surprising discovery in this devil's staircase, which was found mainly in β -Sr0.33V2O5 , is that all the charge modulation vectors of many kinds of CO phases can be represented as a primitive lattice translation vector along the b axis multiplied by several odd numbers. This discovery surely demonstrates interplay between the charge degree freedom and the crystallographic symmetry. We propose two possible mechanisms to explain this phenomenon: "self-charge transfer (carrier redistribution)" between the two subsystems in these compounds and "sequential symmetry reduction" that was discussed in Landau theory of phase transitions. In β -Ca0.33V2O5 we also found a P -T phase diagram similar in outlook but different in detail. The devil's staircase was also observed but it is an incomplete one. Furthermore, the charge modulation vectors in it are shorter than those in β -Sr0.33V2O5 . In β -Pb0.33V2O5 , which has no CO phase at ambient pressure, the pressure-induced antiferromagnetic ordering was observed at around 50 K above 0.5 GPa. Using these two kinds of mechanisms, we also explain the global high-pressure properties in all the stoichiometric divalent β -vanadium bronzes, which were observed as a wide variety of electromagnetic states. In addition, we also discuss a possible key for

Hydrothermal degradation of tetragonal ZrO2 ceramic components used in dental applications

International Nuclear Information System (INIS)

Mukaeda, L.E.; Robin, A.; Taguchi, S.P.

2009-01-01

With the evolution of the dental restoration techniques, a considerable growth in the demand of ceramic products occurred. These materials present good strength associated to reliability. In this work, micrometric and nanometric scale tetragonal ZrO 2 blocks were sintered at 1500 deg C-2h and 1350 deg C-2h, respectively, ground and polished. Ceramics with relative density higher than 98% were obtained. The specimens were immersed in hot water (150 deg C), for times ranging from 10h to 30h. The mass variation of the samples was measured and the crystalline phases present before and after the degradation tests were identified by X-ray diffractometry, in order to evaluate the capacity of these ceramics in resisting to aqueous medium exposure. Materials with nanometric structure present higher resistance to degradation than those with micrometric scale, and this interferes in structural stability after the test, and reduces the martensitic transformation. (author)

Evaluation of copper, aluminum bronze, and copper-nickel for YMP [Yucca Mountain Project] container material

International Nuclear Information System (INIS)

Kass, J.N.

1989-05-01

In this presentation, I will discuss our evaluation of the materials copper, 7% aluminum bronze, and 70/30 copper-nickel. These are three of the six materials currently under consideration as potential waste-packaging materials. I should mention that we are also considering alternatives to these six materials. This work is part of the Yucca Mountain Project (YMP), formerly known as the Nevada Nuclear Waste Storage Investigations (NNWSI) Project. The expected-case environment in our proposed vault is quite different from that encountered at the WIPP site or that expected in a Canadian vault. Our proposed site is under a desert mountain, Yucca Mountain, in southern Nevada. The repository itself will be located approximately 700 feet above the water table and 300 to 1200 feet below the surface of the mountain. The variations in these numbers are due to the variations in mountain topography

Electronic Structures of Purple Bronze KMo6O17 Studied by X-Ray Photoemission Spectra

Science.gov (United States)

Qin, Xiaokui; Wei, Junyin; Shi, Jing; Tian, Mingliang; Chen, Hong; Tian, Decheng

X-ray photoemission spectroscopy study has been performed for the purple bronze KMo6O17. The structures of conduction band and valence band are analogous to the results of ultraviolet photoemission spectra and are also consistent with the model of Travaglini et al., but the gap between conduction and valence band is insignificant. The shape of asymmetric and broadening line of O-1s is due to unresolved contributions from the many inequivalent oxygen sites in this crystal structure. Mo 3d core-level spectrum reveals that there are two kinds of valence states of Molybdenum (Mo+5 and Mo+6). The calculated average valence state is about +5.6, which is consistent with the expectation value from the composition of this material. The tail of Mo-3d spectrum toward higher binding energy is the consequence of the excitation of electron-hole pairs with singularity index of 0.21.

Particular ceramic forms in the central Balkan and northern shores of the Aegean sea in the late bronze age

Directory of Open Access Journals (Sweden)

Bulatović Aleksandar

2011-01-01

Full Text Available This paper deals with the appearance and development of particular ceramic forms that were prevalent on the wider territory from the lower Danube to the northern shores of the Aegean sea during the middle and Late Bronze Age. These forms relate to globular beakers, pear shaped vessels with everted rims with arch shaped handles, cups with handles with plastic applications on their upper surface, etc. Particular attention is devoted to the phenomenon of globular beakers of the LBA in the valleys of Varder, Mesta and Struma rivers. All information collected primarily through analysis of stylistic-typological characteristics of ceramics of the middle and Late Bronze Age - that took into account ritual burials, layout of settlements, trade routes and climactic conditions during that period - points to population movements from the north to the south already by the LBA, i.e. in 15th century BC. These movements contributed to the creation of particular cultural groups in the LBA in the central Balkans, such as the Brnjica cultural group. However, these movements cannot be clearly linked to the so-called Aegean Migration, and for this reason their character and chronology are subject to debate. Ultimately it can be concluded that beakers of the Zimnicea -Cherkovna-Plovdiv type appeared in the late Bronze Age in the Vlasine depression and the Danube valley through the evolution of beaker forms of cultural groups of earlier periods. Almost contemporaneously, during LBA, a variant of this ceramic form, richly ornamented (mostly with spirals and similar in manner to the cultural group Dubovac-Žuto Brdo-Grla Mare- Krna, appeared in the LBA culture in northern Greece. Clearly this stylistic mannerism, with spirals as characteristic elements, spread relatively quickly through successive migrations in the period of 15th-14th century BC, toward the south of the Balkan Peninsula, thus covering the wider territory from the southern tip of the Carpathian mountains

Relative sea-level change in the central Cyclades (Greece) since the Early Bronze Age

Science.gov (United States)

Draganits, E.

2012-04-01

The Aegean is a focus of important cultural achievements in Europe since the Neolithic period. The resulting abundance of archaeological remains, many of them below sea-level represent an advantageous area for the study of local relative sea-level change. We have carried out detailed mapping of Despotiko Island (SW of Antiparos) and its surrounding. Despotiko is situated almost exactly in the center of the Cyclades (as defined nowadays), more so than Delos, and therefore is very well suited for sea-level studies of the Cyclades. This beneficial location, combined with a spacious and protected bay, additionally may explain its former importance as stepping-stone in the Aegean Sea. The island is uninhabited at present, but Early Bronze Age settlement sites and graveyards as well as a large Archaic sanctuary proof its former importance. The sanctuary is situated on a gently northeast dipping slope in the northeast part of Despotiko, in range of sight of the Órmos Despotiko. Since 1997 large parts of this important sanctuary have been excavated during several excavation campaigns. Tectonically, Despotiko, Antiparos and Paros, belong to the Attic-Cycladic Crystalline of the Central Hellenides, a stack of metamorphic tectonic nappes, mainly comprising variable types of gneiss, schist, marble and amphibolite, and tectonic slices of unmetamorphosed sediments on top, separated by low-angle normal faults from the metamorphic units below. Submerged archaeological structures at the sea bottom of the Órmos Despotiko, a Classical marble inscription from the sanctuary and partly submerged agriculture trenches at the east coast Despotiko, indicate that the relative sea-level in this area was some 3 m lower during the Early Bronze Age and still more than 1 m lower during Classical time. These values of relative sea-level rise indicate a subsidence component additional to the global sea-level rise in the investigated time period. Neglecting possible vertical tectonic movements and

Toughening behavior in ceramics associated with the transformation of tetragonal ZrO/sub 2/

International Nuclear Information System (INIS)

Becher, P.F.

1986-01-01

The contribution of the stress-induced phase transformation ZrO/sub 2/ to the fracture toughness of ceramics is described in terms of the zone size, the critical transformation stress and the influence of these parameters on the tetragonal to monoclinic transformation. For example in partially stabilized zirconia (PSZ), the ΔK/sub lC//sup T/ is shown to depend upon the martensite start (M/sub s/) temperature, which can be altered by the solute content and the particle or precipitate size. This behavior is consistent with the thermodynamics of the transformation. Experimental data correspond to the behavior predicted for various systems toughened by the addition of tetragonal ZrO/sub 2/ [e.g. PSZ and Al/sub 2/O/sub 3/-Z/sub 4/O/sub 2/(Y/sub 2/O/sub 3/). The stress required to transform the ZrO/sub 2/ is also modified by residual stresses due to the mismatch in matrix and particle (esp. thermal expansion) properties in the composite systems. The total residual stress acting on a particle is the sum of the particle's internal stress and the stress field of neighboring particles, and as a result, the total residual stress increases with volume fraction of ZrO/sub 2/ (V/sub f/). In the case of the Al/sub 2/O/sub 3/-ZrO/sub 2/ composites the pertinent stresses are tensile in character and thus promote the ZrO/sub 2/ transformation as V/sub f/ increases] For each level of Y/sub 2/O/sub 3/ in the ZrO/sub 2/, ΔK/sub lc//sup T/ then goes through a maximum with increase in V/sub f/ at a value of V/sub f/ where σ/sub R//sup T/ - σ/sub C//sup T/. The critical transformation stress is thus described for different levels of solute (e.g. Y/sub 2/O/sub 3/) in the ZrO/sub 2/. The dependence of ΔK/sub lc//sup T/ upon (σ/sub C//sup T/ - σ/sub R//sup T/) obtained is found to agree with the predicted behavior

Structure and properties of quarternary and tetragonal Heusler compounds for spintronics and spin transver torque applications

Energy Technology Data Exchange (ETDEWEB)

Zamani, Vajiheh Alijani

2012-03-07

shown that the series Mn{sub 3-x}Co{sub x}Ga crystallizes in the inverse tetragonal structure, for x=0.1-0.4 and in the cubic inverse Heusler structure, for x=0.6-1. In this series, while the tetragonal alloys, hard magnets, exhibit the features typically attractive for STT applications, the cubic systems, soft magnets, present 100% spin polarized materials obeying the Slater-Pauling rule. In Mn{sub 2-x}Rh{sub 1+x}Sn series, Mn{sub 2}RhSn crystallizes in the inverse tetragonal structure, shows a hard-magnetic hysteresis loop and does not follow the Slater-Pauling rule. With substituting Mn by Rh, the inverse cubic structure is observed. All cubic samples show perfect Slater-Pauling behavior and a soft hysteresis loop.

Charge-density-wave partial gap opening in quasi-2D KMo{sub 6}O{sub 17} purple bronze studied by angle resolved photoemission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Valbuena, M.A. [LURE, Centre Universitaire Paris-Sud, Bat. 209D, B.P. 34, 91898 Orsay Cedex (France); Avila, J. [Instituto de Ciencia de Materiales de Madrid, ICMM - CSIC, 28049 Madrid (Spain); Synchrotron SOLEIL, L' Orme des Merisiers, Saint-Aubin - B.P. 48, 91192 GIF-SUR-YVETTE Cedex (France); Pantin, V. [LURE, Centre Universitaire Paris-Sud, Bat. 209D, B.P. 34, 91898 Orsay Cedex (France); Drouard, S. [LEPES-CENES, B.P. 166x, 38042 Grenoble, Cedex 9 (France); Guyot, H. [LEPES-CENES, B.P. 166x, 38042 Grenoble, Cedex 9 (France); Asensio, M.C. [Instituto de Ciencia de Materiales de Madrid, ICMM - CSIC, 28049 Madrid (Spain) and Synchrotron SOLEIL, L' Orme des Merisiers, Saint-Aubin - B.P. 48, 91192 GIF-SUR-YVETTE Cedex (France)]. E-mail: asensio@synchrotron-soleil.fr

2006-05-30

Low dimensional (LD) metallic oxides have been a subject of continuous interest in the last two decades, mainly due to the electronic instabilities that they present at low temperatures. In particular, charge density waves (CDW) instabilities associated with a strong electron-phonon interaction have been found in Molybdenum metallic oxides such as KMo{sub 6}O{sub 17} purple bronze. We report an angle resolved photoemission (ARPES) study from room temperature (RT) to T {approx}40 K well below the Peierls transition temperature for this material, with CDW transition temperature T {sub CDW} {approx}120 K. We have focused on photoemission spectra along {gamma}M high symmetry direction as well as photoemission measurements were taken as a function of temperature at one representative k {sub F} point in the Brillouin zone in order to look for the characteristic gap opening after the phase transition. We found out a pseudogap opening and a decrease in the density of states near the Fermi energy, E {sub F}, consistent with the partial removal of the nested portions of the Fermi surface (FS) at temperature below the CDW transition. In order to elucidate possible Fermi liquid (FL) or non-Fermi liquid (NFL) behaviour we have compared the ARPES data with that one reported on quasi-1D K{sub 0.3}MoO{sub 3} blue bronze.

Non destructive neutron diffraction measurements of cavities, inhomogeneities, and residual strain in bronzes of Ghiberti's relief from the Gates of Paradise

Science.gov (United States)

Festa, G.; Senesi, R.; Alessandroni, M.; Andreani, C.; Vitali, G.; Porcinai, S.; Giusti, A. M.; Materna, T.; Paradowska, A. M.

2011-03-01

Quantitative neutron studies of cultural heritage objects provide access to microscopic, mesoscopic, and macroscopic structures in a nondestructive manner. In this paper we present a neutron diffraction investigation of a Ghiberti Renaissance gilded bronze relief devoted to the measurement of cavities and inhomogeneities in the bulk of the sample, along with the bulk phase composition and residual strain distribution. The quantitative measurements allowed the determination of the re-melting parts extension, as well as improving current knowledge about the manufacturing process. The study provides significant and unique information to conservators and restorators about the history of the relief.

Non destructive neutron diffraction measurements of cavities, inhomogeneities, and residual strain in bronzes of Ghiberti's relief from the Gates of Paradise

International Nuclear Information System (INIS)

Festa, G.; Senesi, R.; Alessandroni, M.; Andreani, C.; Vitali, G.; Porcinai, S.; Giusti, A. M.; Materna, T.; Paradowska, A. M.

2011-01-01

Quantitative neutron studies of cultural heritage objects provide access to microscopic, mesoscopic, and macroscopic structures in a nondestructive manner. In this paper we present a neutron diffraction investigation of a Ghiberti Renaissance gilded bronze relief devoted to the measurement of cavities and inhomogeneities in the bulk of the sample, along with the bulk phase composition and residual strain distribution. The quantitative measurements allowed the determination of the re-melting parts extension, as well as improving current knowledge about the manufacturing process. The study provides significant and unique information to conservators and restorators about the history of the relief.

Textured and tungsten-bronze-niobate-doped (K,Na,Li)(Nb,Ta)O3 piezoceramic materials

International Nuclear Information System (INIS)

Soller, Thomas; Bathelt, Robert; Benkert, Katrin; Bodinger, Hermann; Schuh, Carsten; Schlenkrich, Falko

2010-01-01

In this study, the effects of an alkaline-earth niobate doping in tungsten-bronze (TB) stoichiometry on the piezoelectric properties and the phase transition temperatures of lead-free (K,Na,Li)(Nb,Ta)O 3 ceramics were investigated. In particular, the TB compounds barium niobate (BN), barium sodium niobate (BNN) and strontium calcium sodium niobate (SCNN) were investigated. The TB-modified ceramics show promising piezoelectric properties with large-signal piezo coefficients, d 33 * lose to 400 pm/V, planar coupling coefficients, k p , up to 0.45 and Curie temperatures of approximately 310 .deg. C. In addition, the effect of texturing on the undoped (K,Na,Li)(Nb,Ta)O 3 base composition via templated grain growth (TGG) with microcrystalline NaNbO 3 templates was examined. Lotgering factors up to 81% and strain enhancements by a factor 1.5 with large-signal values of d 33 * up to 550 pm/V could be achieved in the textured samples.

Demonstration of Neutron Resonance capture applied to a Cultural Heritage study of Antique Benin Bronzes

International Nuclear Information System (INIS)

Blaauw, M.; Postma, H.; Mutti, P.

2001-01-01

In many cases of historical and archaeological studies physical techniques Instrumental Neutron Activation Analysis (INAA) X-Ray Fluorescence (XRF) and Proton Induced X-ray Emission (PIXE) are used to get information about the element composition of objects. INAA is usually carried out using small samples taken from the object . XRF and PIXE only yield surface information, and require cleaning of the surface to suppress the effect of external contamination. Such actions on artefacts are unwanted. Recently neutron capture resonances have been used to identify elements in artefacts using a set of γray detectors and a time-of flight system at the GELINA facility. This allows identification and quantification of elements of precious artefacts in an fully non-destructive way and with very little activation Because of the novelly of the method the principles of neutron resonance capture analysis (NRC A) will be discussed and the results of an applications to a comparative study of two Benin Bronzes presented

First-principles investigation of mechanical and electronic properties of tetragonal NbAl3 under tension

Science.gov (United States)

Jiao, Zhen; Liu, Qi-Jun; Liu, Fu-Sheng; Tang, Bin

2018-06-01

Using the density functional theory calculations, the mechanical and electronic properties of NbAl3 under different tensile loads were investigated. The calculated lattice parameters, elastic constants and mechanical properties (bulk modulus, shear modulus, Young's modulus, Poisson's ratio, Pugh's criterion and Cauchy's pressure) indicated that our results were in agreement with the published experimental and theoretical data at zero tension. With respect to NbAl3 under tension in this paper, the crystal structure was changed from tetragonal to orthorhombic under tension along the [100] and [101] directions. The NbAl3 crystal has been classified as brittle material under tension from 0 to 20 GPa. The obtained Young's modulus and Debye temperature monotonically decreased with increasing tension stress. Combining with mechanical and electronic properties in detail, the decreased mechanical properties were mainly due to the weakening of covalency.

Thermodynamics of the tetragonal to monoclinic phase transformation in constrained zirconia microcrystals

International Nuclear Information System (INIS)

Garvie, R.C.; Swain, M.V.

1985-01-01

End-point thermodynamic analyses were made of the tetragonal to monoclinic transformation (t -> m) occurring in ZrO 2 precipitates in a Ca-PSZ alloy and particles in Al 2 O 3 -ZrO 2 composites. Calculated plots of the reciprocal critical size for transformation temperature were in excellent agreement with experiment data for both systems. Contributions to the total free energy change included bulk chemical, dilatational and residual shear strain energies and also interfacial energies. The latter term consisted of contributions from the change in the chemical surface free energy, the presence of twin boundaries in the precipitate (particle) - matrix interfacial energy. The major impediment to the transformation was the shear strain energy which could not be reduced sufficiently by twinning alone. The t -> m reaction proceeded spontaneously when the energy barrier was reduced by the response of the particle - matrix interface. The response comprised loss of coherency and grain boundary microcracking for the Ca/PSZ and Al 2 O 3 -ZrO 2 alloys, respectively. These results are in accord with recent suggestions that either a stress-free strain or a free surface is a necessary condition for the initiation of a martensitic transformation. (author)

Barrow of the Copper and Bronze Ages near the Village of Suvorovo, Odessa County

Directory of Open Access Journals (Sweden)

Nicolae Russev

2013-12-01

Full Text Available The article considers materials from a barrow excavated in 1995-1997 in the vicinity of the village of Suvorovo in the tract of Kale (Izmail District, Odessa County. Five graves and some stone and earth structures were uncovered in the barrow. The most ancient grave 5 and perhaps also grave 4 are related to the local variant of the Cernavodă I culture which is dated to the Late Copper Age (the first half of the 4th mill. BC. A ditch with two passages, remains of a cromlech and separately deposited painted vessel of the Cucuteni culture have been connected with grave 5. Grave 3 with bone hook-shaped pendant, paste beads and flint arrow head occupies in stratigraphic sequence later position and according to its features can be attributed to the Early Bronze Age I period or Usatovo culture time (the second half of the 4th mill. BC. Two other graves 1 and 2 with clay vessels belong to the Pit-Grave culture of the 3rd mill. BC.

Rapid climate change did not cause population collapse at the end of the European Bronze Age.

Science.gov (United States)

Armit, Ian; Swindles, Graeme T; Becker, Katharina; Plunkett, Gill; Blaauw, Maarten

2014-12-02

The impact of rapid climate change on contemporary human populations is of global concern. To contextualize our understanding of human responses to rapid climate change it is necessary to examine the archeological record during past climate transitions. One episode of abrupt climate change has been correlated with societal collapse at the end of the northwestern European Bronze Age. We apply new methods to interrogate archeological and paleoclimate data for this transition in Ireland at a higher level of precision than has previously been possible. We analyze archeological (14)C dates to demonstrate dramatic population collapse and present high-precision proxy climate data, analyzed through Bayesian methods, to provide evidence for a rapid climatic transition at ca. 750 calibrated years B.C. Our results demonstrate that this climatic downturn did not initiate population collapse and highlight the nondeterministic nature of human responses to past climate change.

Charge density wave properties of the quasi two-dimensional purple molybdenum bronze KMo 6O 17

Science.gov (United States)

Balaska, H.; Dumas, J.; Guyot, H.; Mallet, P.; Marcus, J.; Schlenker, C.; Veuillen, J. Y.; Vignolles, D.

2005-06-01

The purple molybdenum bronze KMo 6O 17 is a quasi-two-dimensional compound which shows a Peierls transition towards a commensurate metallic CDW state. Electron spectroscopy (ARUPS), Scanning Tunnelling Microscopy (STM) and spectroscopy (STS) as well as high magnetic field studies are reported. ARUPS studies corroborate the model of the hidden nesting and provide a value of the CDW vector in good agreement with other measurements. STM studies visualize the triple- q CDW in real space. This is consistent with other measurements of the CDW vector. STS studies provide a value of several 10 meV for the average CDW gap. High magnetic field measurements performed in pulsed fields up to 55 T establish that first order transitions to smaller gap states take place at low temperature. These transitions are ascribed to Pauli type coupling. A phase diagram summarizing all observed anomalies and transitions is presented.

Calculation of lattice sums and electrical field gradients for the rhombic and tetragonal phases of YBa2Cu3Ox

International Nuclear Information System (INIS)

Lyubutin, I.S.; Terziev, V.G.; Gor'kov, V.P.

1989-01-01

The point charge model is used to calculate the lattice sums and determine the electrical field gradients (EFG) as well as the asymmetry parameters η for all cation sites of the rhombic and tetragonal phases of the superconductor YBa 2 Cu 3 O x . The cases of copper of different valency at the Cu 1 sites are considered separately and EFG and η values are calculated in the vicinity of local defects caused by differences in the number and ordering of the oxygen vacancies at the Cu1 sites

Like a pig out of water: seaborne spread of domestic pigs in Southern Italy and Sardinia during the Bronze and Iron Ages.

Science.gov (United States)

Lega, C; Fulgione, D; Genovese, A; Rook, L; Masseti, M; Meiri, M; Cinzia Marra, A; Carotenuto, F; Raia, P

2017-02-01

Southern Italy has a long history of human occupation and passage of different cultures since the Early Holocene. Repeated, ancient introductions of pigs in several geographic areas in Europe make it difficult to understand pig translocation and domestication in Italy. The archeozoological record may provide fundamental information on this, hence shedding light on peopling and on trading among different ancient cultures in the Mediterranean. Yet, because of the scanty nature of the fossil record, ancient remains from human-associated animals are somewhat rare. Fortunately, ancient DNA analysis as applied to domestic species proved to be a powerful tool in revealing human migrations. Herein, we analyzed 80-bp fragment of mitochondrial DNA control region from 27 Sus scrofa ancient samples retrieved from Southern Italian and Sardinian archeological sites, spanning in age from the Mesolithic to the Roman period. Our results surprisingly indicate the presence of the Near Eastern haplotype Y1 on both Italy's major islands (Sardinia and Sicily) during the Bronze Age, suggesting the seaborne transportation of domestic pigs by humans at least during 1600-1300 BC. The presence of the Italian E2 clade in domestic contexts shows that the indigenous wild boar was effectively domesticated or incorporated into domestic stocks in Southern Italy during the Bronze Age, although the E2 haplotype has never been found in modern domestic breeds. Pigs belonging to the endemic E2 clade were thus traded between the Peninsula and Sardinia by the end of the second millennium BC and this genetic signature is still detected in Sardinian feral pigs.

Changes in X-ray photoelectron spectra of yttria-tetragonal zirconia polycrystal by ion sputtering

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Eiko; Yoshinari, Masao [Tokyo Dental College, Oral Health Science Center, Tokyo, Chiyoda-ku (Japan)

2016-04-15

This paper reports changes in X-ray photoelectron spectroscopy spectra of yttria-tetragonal zirconia polycrystal (Y-TZP) brought about by Ar ion sputtering. The changes in the core-level spectra of Y-TZP suggest that preferential sputtering of oxygen occurred. A new peak was observed near 0 eV binding energy accompanied with changes in the core-level spectra by the sputtering. After 18 h in a high vacuum following the sputtering, the spectra changed by the sputtering were returned to their original shapes. In contrast, the color of Y-TZP was changed from white to pale brown by X-ray irradiation and was changed from pale brown to dark gray by ion sputtering. However, when the new peak near 0 eV decreased after 18 h, no color change was observed. Therefore, it is thought that the new peak was mainly derived from electrons trapped in various kinds of oxygen vacancies created by the sputtering in other than color centers. (orig.)

Experimental study of stress-induced localized transformation plastic zones in tetragonal zirconia polycrystalline ceramics

International Nuclear Information System (INIS)

Sun, Q.; Zhao, Z.; Chen, W.; Qing, X.; Xu, X.; Dai, F.

1994-01-01

Stress-induced martensitic transformation plastic zones in ceria-stabilized tetragonal zirconia polycrystalline ceramics (Ce-TZP), under loading conditions of uniaxial tension, compression, and three-point bending, are studied by experiments. The transformed monoclinic phase volume fraction distribution and the corresponding plastic strain distribution and the surface morphology (surface uplift) are measured by means of moire interferometry, Raman microprobe spectroscopy, and the surface measurement system. The experimental results from the above three kinds of specimens and methods consistently show that the stress-induced transformation at room temperature of the above specimen is not uniform within the transformation zone and that the plastic deformation is concentrated in some narrow band; i.e., macroscopic plastic flow localization proceeds during the initial stage of plastic deformation. Flow localization phenomena are all observed in uniaxial tension, compression, and three-point bending specimens. Some implications of the flow localization to the constitutive modeling and toughening of transforming thermoelastic polycrystalline ceramics are explored

Phenomenological Equations Relating Various Critical Anomalies above a Cubic-to-Tetragonal Phase Transition Point

Science.gov (United States)

Hamano, Katsumi; Hirotsu, Shunsuke

1980-01-01

Phenomenological equations are derived which interrelate the anomalies in various thermodynamic quantities above the transition point of a cubic-to-tetragonal phase transition caused by an instability of a triply degenerate soft mode. The anomalous part of the Gibbs free energy is assumed to be a simple sum of the three parts which represent the contributions from the three fluctuation components. A cylindrical approximation is adopted to each of the three contributions by taking into account the symmetry of the fluctuations. The theory predicts that the adiabatic elastic compliances, s11s, s12s, and also s11s-s12s should exhibit anomalies proportional to the anomaly in the specific heat at constant pressure. This is in marked contrast with the result of the generalized Pippard equations derived by Garland, and by Janovec. The new equations are successfully tested for KMnF3, CsPbCl3, and CsPbBr3. The β-γ transition of NH4Br is also discussed.

Effect of intracrystalline water on micro-Vickers hardness in tetragonal hen egg-white lysozyme single crystals

International Nuclear Information System (INIS)

Koizumi, H; Kawamoto, H; Tachibana, M; Kojima, K

2008-01-01

Mechanical properties of high quality tetragonal hen egg-white lysozyme single crystals which are one type of protein crystal were investigated by the indentation method. The indentation marks were clearly observed on the crystal surface and no elastic recovery of them occurred. The value of the micro-Vickers hardness in the wet condition was estimated to be about 20 MPa at room temperature. The hardness greatly depended on the amount of intracrystalline water (mobile water) contained in the crystals. The hardness increased with increasing evaporation time to air at room temperature. It reached the maximum at about 260 MPa, which is 13 times as much as that in the wet condition. The origin of such a change in hardness was explained in terms of the dislocation mechanisms in lysozyme single crystals

A new find of macrofossils of feather grass (Stipa) in an Early Bronze Age storage pit at Vliněves, Czech Republic: local implications and possible interpretation in a Central European context

Czech Academy of Sciences Publication Activity Database

Bieniek, A.; Pokorný, Petr

2005-01-01

Roč. 14, č. 4 (2005), s. 295-302 ISSN 0939-6314 R&D Projects: GA ČR(CZ) GA206/00/D073 Institutional research plan: CEZ:AV0Z80020508 Keywords : Stipa * gathering * Neolithic * Bronze Age * Czech Republic * Poland Subject RIV: AC - Archeology, Anthropology, Ethnology Impact factor: 0.739, year: 2005

Structural and physical properties of the tetragonal superconductors lanthanum barium alkaline earth copper oxides LaBaACu3O7-d (A = calcium and strontium)

NARCIS (Netherlands)

Fu, W.T.; Zandbergen, H.W.; Beek, van der C.J.; Verheijen, A.A.; Jongh, de L.J.; Brabers, V.A.M.

1989-01-01

The compounds LaBaACu3O7-d (A = Ca and Sr) have been prepared and characterized by X-ray diffraction and electron microscopy. Their structure is similar to that of YBa2Cu3O7, except that they are tetragonal. Electron diffraction of LaCaBaCu3O7-d reveals the presence of a weak superstructure having

Effect of MnO doping on the structure, microstructure and electrical properties of the (K,Na,Li)(Nb,Ta,Sb)O{sub 3} lead-free piezoceramics

Energy Technology Data Exchange (ETDEWEB)

Rubio-Marcos, F., E-mail: fernando.rubio-marcos@unilim.fr [Laboratoire de Science des Procedes Ceramiques et de Traitements de Surface, UMR 6638 CNRS, Universite de Limoges, Centre Europeen de la Ceramique, 12, rue Atlantis, 87068 Limoges Cedex (France); Marchet, P. [Laboratoire de Science des Procedes Ceramiques et de Traitements de Surface, UMR 6638 CNRS, Universite de Limoges, Centre Europeen de la Ceramique, 12, rue Atlantis, 87068 Limoges Cedex (France); Vendrell, X. [Grup de Quimica de l' Estat Solid, Departament de Quimica Inorganica, Universitat de Barcelona, 08028 Barcelona (Spain); Romero, J.J. [Electroceramic Department, Instituto de Ceramica y Vidrio, CSIC, Kelsen 5, 28049 Madrid (Spain); Remondiere, F. [Laboratoire de Science des Procedes Ceramiques et de Traitements de Surface, UMR 6638 CNRS, Universite de Limoges, Centre Europeen de la Ceramique, 12, rue Atlantis, 87068 Limoges Cedex (France); Mestres, L. [Grup de Quimica de l' Estat Solid, Departament de Quimica Inorganica, Universitat de Barcelona, 08028 Barcelona (Spain); Fernandez, J.F. [Electroceramic Department, Instituto de Ceramica y Vidrio, CSIC, Kelsen 5, 28049 Madrid (Spain)

2011-09-01

Highlights: {center_dot} MnO doping effects on structure and properties of (K,Na,Li)(Nb,Ta,Sb)O{sub 3} piezoceramics. {center_dot} The structure changes towards an orthorhombic symmetry for higher MnO concentrations. {center_dot} High doping levels induce a tetragonal tungsten-bronze secondary phase. {center_dot} Mn{sup 2+} doping modifies the phase transition temperature and the piezoelectric properties. {center_dot} Manganese doping increases the mechanical quality factor Q{sub m}. - Abstract: Mn{sup 2+}-doped (K,Na,Li)(Nb,Ta,Sb)O{sub 3} lead-free piezoelectric ceramics have been prepared by a conventional sintering technique. The effects of Mn{sup 2+} doping on the phase structure, microstructure and ferro-piezoelectric properties of the ceramics have been evaluated. MnO doping modifies the (K,Na,Li)(Nb,Ta,Sb)O{sub 3} structure, giving rise to the appearance of a TTB-like secondary phase and to changes on the orthorhombic to tetragonal phase transition temperature. The modification of this temperature induces a reduction of the piezoelectric constants, which is accompanied by an increase on the mechanical quality factor. Mn{sup 2+} ions incorporate into the perovskite structure in different off ways depending on their concentration.

Improvement of the phase diagram for the pseudobinary PbNb2O6-BaNb2O6 system

International Nuclear Information System (INIS)

Venet, M.; Zabotto, F. L.; Eiras, J. A.; Garcia, D.

2009-01-01

Characteristics of phase transitions of lead barium niobate compositions around the morphotropic phase boundary were investigated. Using structural characterizations, it was found that the morphotropic phase boundary extends toward a wide composition range, in which both tetragonal (4mm) and orthorhombic (m2m) tungsten bronze phases coexist. In addition, on heating, two phase transitions were observed for all the studied compositions. First, the fraction with m2m symmetry phase transforms into the 4mm symmetry one and, second, the 4mm symmetry phase, which represents the whole material, transforms into the paraelectric phase (4/mmm symmetry). The phase transition temperatures were determined from dielectric characterizations. These results helped to improve the phase diagram of the pseudobinary PbNb 2 O 6 -BaNb 2 O 6 system around the morphotropic phase boundary region.

OSL Age Determination of the Hearths in a Bronze Age Dwelling Site by using Bayesian Statistics

International Nuclear Information System (INIS)

Kim, Myung Jin; Yang, Hye Jin; Hong, Duk Geun

2011-01-01

OSL dating for three hearths having the sequence of use and discard in No. 29 and 29-1 dwelling sites at Sogol cultural site was carried out. Resulting from the deconvolution of natural CW-OSL decay curve and thermal zeroing test, it was turned out that OSL signal was entirely composed of the heat- and light-sensitive fast component with high photoionization cross-section and all quartz OSL signals were thermally bleached under 300 .deg. C which is the minimum temperature related to heating and cooking in Bronze age. After dose recovery test and plateau test, paleodose of each hearth sample was evaluated by using SAR method, and OSL age was determined from the ratio of paleodose to annual dose rate. For the purpose of the precision improvement of OSL age, Bayesian statistics was applied to each hearth's age and the archaeological sequence information. Finally, it could be concluded to the accurate use period of each hearth from the resultant OSL ages

OSL Age Determination of the Hearths in a Bronze Age Dwelling Site by using Bayesian Statistics

Energy Technology Data Exchange (ETDEWEB)

Kim, Myung Jin [Neosiskorea Co. Ltd., Seoul (Korea, Republic of); Yang, Hye Jin [Baekje Cultural Properties Research Institute, Gongju (Korea, Republic of); Hong, Duk Geun [Kangwon National University, Chuncheon (Korea, Republic of)

2011-06-15

OSL dating for three hearths having the sequence of use and discard in No. 29 and 29-1 dwelling sites at Sogol cultural site was carried out. Resulting from the deconvolution of natural CW-OSL decay curve and thermal zeroing test, it was turned out that OSL signal was entirely composed of the heat- and light-sensitive fast component with high photoionization cross-section and all quartz OSL signals were thermally bleached under 300 .deg. C which is the minimum temperature related to heating and cooking in Bronze age. After dose recovery test and plateau test, paleodose of each hearth sample was evaluated by using SAR method, and OSL age was determined from the ratio of paleodose to annual dose rate. For the purpose of the precision improvement of OSL age, Bayesian statistics was applied to each hearth's age and the archaeological sequence information. Finally, it could be concluded to the accurate use period of each hearth from the resultant OSL ages.

Hydrothermal degradation of tetragonal ZrO{sub 2} ceramic components used in dental applications; Efeito da degradacao em meio aquoso de componentes ceramicos a base de ZrO{sub 2} tetragonal para uso odontologico

Energy Technology Data Exchange (ETDEWEB)

Mukaeda, L.E.; Robin, A.; Taguchi, S.P. [Universidade de Sao Paulo (DEMAR/EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de Lorena. Dept. de Engenharia de Materiais; Santos, C. [ProtMat Materiais Avancados, Guaratingueta, SP (Brazil)

2009-07-01

With the evolution of the dental restoration techniques, a considerable growth in the demand of ceramic products occurred. These materials present good strength associated to reliability. In this work, micrometric and nanometric scale tetragonal ZrO{sub 2} blocks were sintered at 1500 deg C-2h and 1350 deg C-2h, respectively, ground and polished. Ceramics with relative density higher than 98% were obtained. The specimens were immersed in hot water (150 deg C), for times ranging from 10h to 30h. The mass variation of the samples was measured and the crystalline phases present before and after the degradation tests were identified by X-ray diffractometry, in order to evaluate the capacity of these ceramics in resisting to aqueous medium exposure. Materials with nanometric structure present higher resistance to degradation than those with micrometric scale, and this interferes in structural stability after the test, and reduces the martensitic transformation. (author)

Une fosse du Bronze final IIb dans le Val d’Orléans à Sandillon (Loiret : données archéologiques et contexte environnemental A Late Bronze Age pit IIb in the Val d’Orléans at Sandillon (Loiret: archaeological data and environmental context

Directory of Open Access Journals (Sweden)

Hélène Froquet

2008-06-01

Full Text Available Un diagnostic archéologique réalisé en 2004 à Sandillon (Loiret a permis la découverte d’une occupation du Bronze final IIb dans la plaine alluviale de la Loire. Les structures sont peu nombreuses, mais une fosse se distingue par un ensemble céramique exceptionnel par sa richesse, sa conservation et la présence de formes encore inconnues en région Centre. Ce corpus céramique, corrélé par une datation par radiocarbone, offre désormais un jalon fiable pour la région. Par ailleurs, ces vestiges ont pu être replacés dans leur environnement immédiat grâce à une étude géomorphologique et à l’analyse des restes carpologiques contenus dans la fosse. Ainsi, le croisement des données permet de tenter une approche paléo environnementale sur une occupation en contexte fluviatile et de préciser les relations entre l’homme et son milieu durant cette période chronologique.An archaeological diagnostic carried out in 2004 at Sandillon (Loiret enabled the discovery of a final Bronze Age IIb occupation in the alluvial Loire valley. There are few structures but one pit is noteworthy for a ceramic collection, exceptional in its abundance, its preservation and the presence of previously unknown forms in the Centre region. This ceramic corpus, dated by radiocarbon, henceforth provides a reliable standard for the region. Moreover, these relics could be set in their immediate environment thanks to a geomorphological study and to the analysis of carpological remains contained in the pit. So, the crossing of data allows us to attempt an environmental paleolithic approach to an occupation in a freshwater context and to clarify the relationship between man and his environment in this chronological period.

Abertura floral de Dendranthema grandiflora Tzvelev. ´Bronze Repin´após rmazenamento a frio seguido de “pulsing” Floral opening of Dendranthema grandiflora Tzvelev. ´Bronze Repin´after cold storage followed by pulsing

Directory of Open Access Journals (Sweden)

Rogério Antônio Bellé

2004-02-01

Full Text Available Visando estudar a abertura de inflorescências e a vida de vaso de crisântemo (Dendranthema grandiflora Tzvelev. ‘Bronze Repin’ colhido precocemente, montou-se um experimento em delineamento inteiramente casualizado bifatorial 2 x 6 com cinco repetições, realizado no Departamento de Fitotecnia da Universidade Federal de Santa Maria. As hastes foram armazenadas a 2ºC ou 5ºC por sete dias, sendo em seguida tratadas com soluções de “pulsing” por 24h e mantidas em vasos com água de torneira, renovada a cada dois dias. As soluções utilizadas foram: Água (testemunha; Tiosulfato de Prata-STS 11mg.L-1 (Crysal AVB; Ácido Giberélico-GA3 50mg.L-1 (Pro-gibb; Hipoclorito de Sódio-NaOCl 200mg.L-1; 8-Hidroxiquinolina-8-HQ 100mg.L-1; Tiabendazole-TIBA 100mg.L-1(Tecto 100. Com exceção da testemunha, as outras soluções continham 2% de Sacarose. Com estes tratamentos, observou-se que não foi possível uma abertura perfeita da inflorescência, mas a vantagem foi de prolongar a sua vida, podendo-se colocá-las no mercado num momento mais oportuno.The study of opening of inflorescences and the vase life (Dendranthema grandiflora Tzvelev. ‘Bronze Repin’ early picked of chysanthemum, was carried out in an experiment entirely set up in bifactorial 2 x 6 with five repetitions, at the Department of Fitotecnia of Santa Maria’s Federal University. The stems were stored at 2ºC or 5ºC for 7 days, prior to being treated with pulsing solutions for 24 hours and maintained in vases with distilled water, renewed every two days. The solutions used as follows: Water (control; Silver Thiosulfate-STS 11mg.L-1 (Crysal AVB; Giberelic Acid-GA3 50mg.L-1 (Pro-gibb; Sodium Hipochloride-NaOCl 200mg.L-1; 8-Hidroxyquinoline-8-HQ 100mg.L-1; Tiabendazole-TIBA 100mg.L-1 (Tecto 100. With the exception of the control, all solutions contained 2% sucrose. Perfect opening of the flower was not achieved, but vase life could be extended in order to place them in the

The role of plants in the economy of Tell Arbid, north-east Syria, in the Post-Akkadian Period and Middle Bronze Age

Directory of Open Access Journals (Sweden)

Wasylikowa Krystyna

2013-12-01

Full Text Available Archaeological fieldwork carried out at the Tell Arbid site in north-eastern Syria exposed settlement remains dating from the early 3rd millennium BC to the mid 2nd millennium BC. Recent excavations in Sector P, on the eastern slope of the site, revealed the existence of a significant occupation of the Post-Akkadian/ Early Jazirah V period and of levels dated to the Early and Classic Khabur Ware/Old Jazirah/Middle Bronze Age I-II periods. Cereal remains were dominated by grains and ear fragments of hulled two-rowed barley Hordeum distichon. Less numerous were wheats represented by emmer Triticum dicoccon, einkorn T. monococcum, and macaroni wheat T. durum. The presence of bread wheat T. aestivum and six-rowed barley Hordeum vulgare could not be excluded. The two periods contained similar sets of cereals, but in the Post-Akkadian Period the percentage of hulled wheat remains was higher, while in the Middle Bronze Age (particularly in its younger phase naked wheat slightly exceeded hulled wheats. Legumes were represented by only very few seeds of lentil Lens culinaris and bitter vetch Vicia ervilia. Diaspores of wild plants were very abundant, particularly those from the families of grasses and legumes. The considerable number of ear and culm fragments probably belonging to cereals as well as numerous seeds/fruits of wild plants suggests that the plant remains originated from fodder or animal dung or belonged to threshing waste. The presence of grass stems with nodes indicated that cereals were reaped low on the straw; occasional use of uprooting was suggested by the occurrence of basal culm fragments with traces of rootlets.

Oxidation of uraninite: does tetragonal U3O7 occur in nature?

International Nuclear Information System (INIS)

Janeczek, J.; Ewing, R.C.; Thomas, L.E.

1993-01-01

Samples of uraninite and pitchblende annealed at 1200 C in H 2 , and untreated pitchblende were sequentially oxidized in air at 180-190 C, 230 C, and 300 C. Uraninite and untreated pitchblende oxidized to the U 4 O 9 -type oxide, and their X-ray symmetry remained isometric up to 300 C. Reduced pitchblende after oxidation to UO 2+x and U 4 O 9 -type oxides transformed into α-U 3 O 8 at 300 C. Two major mechanisms control uraninite and untreated pitchblende stability during oxidation: (1) Th and/or REE maintain charge balance and block oxygen interstitials near impurity cations; (2) the uraninite structure saturates with respect to excess oxygen and radiation-induced oxygen interstitials. Untreated pitchblende during oxidation behaved similarly to irradiated UO 2 in spent nuclear fuel; whereas, reduced pitchblende resembled nonirradiated UO 2 . An analysis of the data in the literature, as well as our own efforts to identify U 3 O 7 in samples from Cigar Lake, Canada, failed to provide conclusive evidence of the natural occurrence of tetragonal α-U 3 O 7 . Most probably, reported occurrences of U 3 O 7 are mixtures of isometric uraninites of slightly different compositions. (orig.)

Leather material found on a 6th B.C. Chinese bronze sword: A technical study

Science.gov (United States)

Luo, Wugan; Si, Yi; Wang, Hongmin; Qin, Ying; Huang, Fengchun; Wang, Changsui

2011-09-01

During July to November, 2006, an important archaeological excavation was conducted in Yun country, Hubei province, southern China. Chinese archaeologists found some remnant of leather materials, covered with red pigments, on a 6th century B.C. Chinese bronze sword. To understand the technology/ies that may have been utilized for manufacturing the leathers, a combined of Raman spectroscopy, FT-IR and XRF was thus applied to the remnant of leather materials. Raman analyses showed that red pigment on the leather was cinnabar (HgS). FT-IR and XRF analyses indicated that the content of some elements, such as Ca (existing as CaCO 3) and Fe (existing as Fe 2O 3), were much higher than those in the surrounding grave soil. The results inferred an application of lime depilation and retting, and the Fe-Al compound salt as tanning agent. And it was furthermore implicated that the Fe-Al salt tanning technique had been developed in the middle and late Spring and Autumn Period of China.

Tetragonal fcc-Fe induced by κ -carbide precipitates: Atomic scale insights from correlative electron microscopy, atom probe tomography, and density functional theory

Science.gov (United States)

Liebscher, Christian H.; Yao, Mengji; Dey, Poulumi; Lipińska-Chwalek, Marta; Berkels, Benjamin; Gault, Baptiste; Hickel, Tilmann; Herbig, Michael; Mayer, Joachim; Neugebauer, Jörg; Raabe, Dierk; Dehm, Gerhard; Scheu, Christina

2018-02-01

Correlative scanning transmission electron microscopy, atom probe tomography, and density functional theory calculations resolve the correlation between elastic strain fields and local impurity concentrations on the atomic scale. The correlative approach is applied to coherent interfaces in a κ -carbide strengthened low-density steel and establishes a tetragonal distortion of fcc-Fe. An interfacial roughness of ˜1 nm and a localized carbon concentration gradient extending over ˜2 -3 nm is revealed, which originates from the mechano-chemical coupling between local strain and composition.

Effect of friction stir processing on erosion–corrosion behavior of nickel–aluminum bronze

International Nuclear Information System (INIS)

Lotfollahi, M.; Shamanian, M.; Saatchi, A.

2014-01-01

Highlights: • The average hardness value of the FSP samples was higher than cast sample. • Erosion–corrosion rate of the FSP samples was higher than cast sample. • The gravimetric analysis showed a negative synergy. - Abstract: In the present investigation, effects of Friction Stir Processing (FSP) on Erosion–Corrosion (E–C) behavior of Nickel–Aluminum Bronze (NAB) were studied by weight-loss measurements and surface characterization using an impingement jet test system. After FSP, the initial coarse microstructure of the cast NAB was transformed to a fine structure, and the porosity defects were eliminated. In addition, different FSP structures were produced by each rotation rate. Microhardness measurements showed a marked increase in FSP samples depending upon the FSP parameters. E–C tests were carried out by erodent at kinetic energies about 0.45 μJ and in 30°, 60° and 90° impact angles to simulate actual service conditions. The maximum weight-loss was observed in FSP samples and Scanning Electron Microscopy (SEM) results showed signs of brittle fracture mechanism in FSP samples. By gravimetric analysis, the degree of synergy was evaluated at 0.45 μJ kinetic energy at normal impact angle and negative synergy result implies the presence of a protective film on all sample surfaces

Electrochemical and spectroscopic evidences of corrosion inhibition of bronze by a triazole derivative

International Nuclear Information System (INIS)

Dermaj, A.; Hajjaji, N.; Joiret, S.; Rahmouni, K.; Srhiri, A.; Takenouti, H.; Vivier, V.

2007-01-01

The electrochemical behavior of the bronze (Cu-8Sn in wt%) was investigated in 3% NaCl aqueous solution, in presence and in absence of a corrosion inhibitor, the 3-phenyl-1,2,4-triazole-5-thione (PTS). The inhibiting effect of the PTS was evidenced for concentrations higher than 1 mM for the cathodic process whereas its effect was clearly seen with a concentration as low as 0.1 mM for the anodic process. A significant positive shift of the corrosion potential was also observed, and its inhibiting effect increased with both its concentration and the immersion time of the sample. From voltammetry and electrochemical impedance spectroscopy experiments, the inhibiting efficiency of the PTS was found to be in the 94-99% range for 1 mM concentration. Scanning electron microscopy and X-ray energy dispersion analysis of the specimen surface show the presence of sulphur on the surface. Raman micro-spectrometry study confirms the protective effect of the PTS in aqueous solution through three types of interactions with the electrode, namely the adsorption of the inhibitor in a flat configuration, the formation of copper-thiol molecules, and when copper is released, the formation of a polymeric complex

Dynamic characteristics of Great Bronze Buddha of Kamakura using microtremor

International Nuclear Information System (INIS)

Nakamura, Y; Saita, J.; Tachibana, M.; Sato, T.

2015-01-01

The second largest bronze Buddha in Japan built in around 1250AD at Kamakura immediately above the focal region of the 1923 Kanto earthquake. Great Buddha of Kamakura has still remained basically its original shape, though it has been suffered several natural disasters as losing its hall. Especially, although the 1703 and 1923 Kanto earthquakes caused settlement and sliding of the basement over 0.3 m., the body has been not suffered serious damage. This statue was casted in order from the bottom with many joints. The joint between the head and the body was noticed because it is reinforced by FRP, Fiber Reinforced Plastic, at the time of the last major repair in 1961. And ingenuity was exercised to fence off the earthquake motion over 400 Gal with sliding the body on the basement, to reduce the load for the neck during earthquake. This is the first example of the earthquake isolation system for cultural properties in Japan. Over 50 years passed after the during earthquake motion, microtremor measurement was conducted. As a result of the primary investigation in 2009, the surrounding ground was estimated that liquefaction was occurred at the front and right sides of the basement and the basement suffered damage as settlement. However, it is considered that the propagation of the earthquake motion for the statue was interrupted because of the liquefaction. Thus, it seems that the damage for the statue itself was prevented because of namely the natural isolation system. Additional y in 2013 microtremor of the statue itself was measured for making clear the connection status between the body and the head.

Initial Bacterial Adhesion on Different Yttria-Stabilized Tetragonal Zirconia Implant Surfaces in Vitro

Directory of Open Access Journals (Sweden)

Lamprini Karygianni

2013-12-01

Full Text Available Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm formation, infection and treatment failure. The aim of this study was to examine the initial bacterial adhesion on different implant materials in vitro. Four implant biomaterials were incubated with Enterococcus faecalis, Staphylococcus aureus and Candida albicans for 2 h: 3 mol % yttria-stabilized tetragonal zirconia polycrystal surface (B1a, B1a with zirconium oxide (ZrO2 coating (B2a, B1a with zirconia-based composite coating (B1b and B1a with zirconia-based composite and ZrO2 coatings (B2b. Bovine enamel slabs (BES served as control. The adherent microorganisms were quantified and visualized using scanning electron microscopy (SEM; DAPI and live/dead staining. The lowest bacterial count of E. faecalis was detected on BES and the highest on B1a. The fewest vital C. albicans strains (42.22% were detected on B2a surfaces, while most E. faecalis and S. aureus strains (approximately 80% were vital overall. Compared to BES; coated and uncoated zirconia substrata exhibited no anti-adhesive properties. Further improvement of the material surface characteristics is essential.