bluuebunny/crossref_metadata_2025 huggingface dataset:
A Theoretical Investigation of Polymer-Nanoparticles as Miscibility Improvers in All-Polymer Nanocomposites
Authors: Ruiz de Luzuriaga Alaitz , Grande Hans , Pomposo Jose A.
Published: March 2009

The miscibility behaviour of polymer-nanoparticle / linear-polymer blends
(all-polymer nanocomposites) has been investigated using an incompressible mean-field
theoretical model that accounts for combinatorial, temperature-dependent exchange
interaction energy and nanoparticle-driven effects. The theory is employed to predict the
phase diagram of poly(styrene)-nanoparticle (PS-np) / linear-poly(vinyl methyl ether)
(PVME) nanocomposites from room temperature to 675 K. Complete miscibility is
predicted for PS-nanoparticles with radius < 6 nm blended with PVME (molecular
weight 62 500 g/mol, nanoparticle volume fraction 20 %). The effect of PVME
molecular weight and blend composition on the miscibility diagram is also addressed.
When compared to the well-known experimental phase diagram of linear-PS / PVME
blends displaying lower critical solution temperature (LCST) behaviour, the miscibility
improving effect of sub-10 nm PS-nanoparticles is clearly highlighted. In terms of the
model, this favourable nanoscale effect arises mainly from the reduced stretching
induced by the sub-10 nm nanoparticles and the increased exothermic contacts when
compared to nanoparticles with sizes > 10 nm.
Structural and Morphological Characterization of Magnetron Sputtered Nanocrystalline Vanadium Oxide Films for Thermochromic Smart Surfaces
Authors: Batista C. , Teixeira Vasco , Carneiro Joaquim
Published: March 2009

Nanocrystalline vanadium oxide thin films have been deposited by reactive DC
magnetron sputtering onto glass substrates under different processing conditions. Structural analysis
and phase identification have been carried out by means of X-ray diffractometry (XRD). The
surface morphologies of the different films have been examined by both scanning electron
microscopy (SEM) and atomic force microscopy (AFM). The XRD results revealed single and
multiple phase oxides such as VO2(B), VO2(M), V2O5, etc. with considerable differences
concerning to surface morphologies, as observed by SEM and AFM. The effects the O2/Ar flow
ratio, DC current, and working pressure on the phases formed and growth rates is discussed.
Moreover, VO2(M) films exhibited different morphologies concerning to grain size and shape as
well as dissimilar preference in crystal orientation, as a result of the processing conditions. The
optical/thermochromic response of the VO2(M) specimens deposited under different growth rate
conditions was evaluated by optical spectrophotometry and related to the respective structural
characteristics.
Durable Unsymmetrical Zinc Phthalocyanine for Near IR Sensitization of Nanocrystalline TiO2 Films with Non-Volatile Redox Electrolytes
Authors: Giribabu L. , Vijay Kumar C. , Raghavender M. , Somaiah K. , Yella Reddy P. , Venkateswara Rao P.
Published: March 2009

We are presenting our results based on unsymmetrical zinc phthalocyanine by adopting
‘push-pull’ concept for the nanocrystalline dye-sensitized solar cells. Using this sensitizer in
combination with nonvolatile organic-solvent-based electrolytes, we obtained a photovoltaic
efficiency of 1.52% under standard global AM 1.5 sunlight and compared the results with volatile
organic-solvent based electrolyte. These devices exhibit admirable stability when subjected to
continuous thermal stress at 60 oC for 1000 h. The sensitizer is thermally stable up to 150 oC and
can be useful for roof top applications.
Structure and Elastic Modulii of Silicon Nanotubes
Authors: Verma Veena , Dharamvir Keya , Jindal V.K.
Published: March 2009

Based on the assumption that sp3 hybridization is more stable in bulk silicon, this study
is a step forward in understanding the structures and mechanical properties of silicon nanotubes
(SiNT). Using the well tested form of Tersoff potential we have calculated cohesive energy and
other parameters for SiNT of various diameters and chiralities. Using this potential, the results
obtained for bulk silicon are satisfactory, so we expect that the same potential would work well with
SiNT as well. We calculated Young’ modulus and shear modulus for SiNT. Young’s modulus lies
in the range of 100- 200 GPa which is about 10-20 times lower than CNT and shear modulus lies
between 200-300 GPa. This work shall motivate further theoretical and experimental work in the
field of nanostructures.
Stability of Gold Nanoparticles in Sol - Gel Silica Films
Authors: Rentería-Tapia Víctor , García-Macedo Jorge A. , Valverde-Aguilar Guadalupe
Published: March 2009

Sol-gel silica films containing gold ions were prepared with and without citric acid (capping agent). Heat treatment of these films in hydrogen atmosphere (reducing agent) leads to the formation of gold nanoparticles. The experimental optical spectra of the gold nanoparticles prepared with citric acid revealed a surface plasmon resonance band located at 585 nm. Transmission electronic microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) measurements revealed the formation of prolate gold nanoparticles (6.4 nm of average diameter) and aggregates dispersed in silica matrix. On the other hand, gold nanoparticles in sol-gel silica films prepared without citric acid exhibited a splitting in surface plasmon resonance band for the prolate gold nanoparticles with an average size <12 nm. On further annealing the samples in oxygen atmosphere, the gold nanoparticles prepared with citric acid exhibited high stability in contrast to the samples prepared without citric acid. This stability probably depends on the formation of a microporous structure of silica produced by the citric acid. The optical properties of the metallic nanoparticles were modeled using Gans theory.
Two-Dimensional Modulated Interfacial Structures of Highly Epitaxial Ferromagnetic (La,Ca)MnO3 and Ferroelectric (Pb,Sr)TiO3 Thin Films on (001) MgO
Authors: Jiang Jiechao , He J. , Meletis Efstathios I. , Liu Jian , Yuan Z. , Chen Chong Lin
Published: March 2009

Two-dimensional in-plane interface structures of highly epitaxial perovskite (La,Ca)MnO3 (LCMO) and (Pb,Sr)TiO3 (PSTO) thin films on salt-rock type MgO substrate were studied using Transmission Electron Microscopy (TEM). Cross-section TEM studies revealed that both LCMO and PSTO films are good single crystal quality and have atomic sharp interface with respect to the MgO substrate with -6.4% and -6.2% lattice mismatch, respectively. Electron Diffraction Patterns (EDPs) of plan-view LCMO/MgO and PSTO/MgO interfaces exhibit double diffraction spots. An analytical approach was employed using double diffraction to study the two-dimensional in-plane interfaces of perovskite structure films on the salt-rock type substrate. The lattice mismatch near the interface regions was determined using EDPs of the plan-view interfaces and found to be -8.0% for LCMO/MgO and -7.14% for PSTO. Both latter values are larger than those obtained using cross-section TEM. Studies of the sharpness of double diffraction spots and plan-view high resolution (HR) TEM brought a conclusion that the PSTO film is well commensurate with the MgO substrate over large areas, whereas LCMO film is only locally commensurate with the substrate. These studies provide additional evidence to our previous observations that plan-view TEM of the interface is able to provide critical and valuable information that is lacking from the cross-section TEM analysis.
Production of TiAl(Ti3Al)/Al2O3 Nanocomposite
Authors: Kamali Ali Reza , Hadavi S.M.M. , Baboee J. , Razavizadeh Hekmat
Published: March 2009

Titanium Aluminide-based composites with Al2O3 reinforcement can be produced via reaction of Al
with TiO2. These composites are considered as low-cost materials for high temperature applications.
Addition of KClO4 to the TiO2/Al system was investigated in this research. On the basis of the
results obtained, addition of KClO4 to the mixture of TiO2/Al and subsequent heating, results in
titanium aluminide/alumina nanometric particle formation with dimensions of about 30 nm.
Densification of this composite powder leads to production of a titanium aluminide-alumina
nanocomposite body. Dimensions of the alumina phase are in the range of 100-150nm.
Photoluminescent Photonic Devices from Nanostructured Porous Silicon Fabricated Using Lightly Doped Silicon
Authors: Sarracino Martínez O. , Escorcia-Garcia J. , Gracia-Jiménez J.M. , Agarwal V.
Published: March 2009

In this work, we report the fabrication of porous silicon multilayers using lightly doped, p-type, silicon wafers (resistivity: 14-22 Ω-cm) by pulsed anodic etching. The optical properties have been found to be strongly dependent on the duty-cycle and frequency of the applied current. Less than 50 % of duty-cycle, at low frequencies, is found to show very rough porous silicon – crystalline silicon (PS-cSi) interface. Use of duty cycle above 50 %, in a certain range of frequencies, is found to make the interface smooth. The optical properties of the photonic devices are investigated for 50 % and 75 % of duty-cycle, for different frequencies in the range of 0-1000 Hz, using the current densities of 10, 90 and 150 mA/cm2. The possibility of fabricating rugate filter with this resistivity is also explored.
Growth and Luminescence of Nanowires and Oriented Nanoplate Arrays of Mg Doped ZnO
Authors: Urbieta A. , Fernández P. , Piqueras J.
Published: March 2009

Sintering of a ZnO-MgO powder mixture under argon flow leads to the growth of elongated Mg doped ZnO structures such as stacks of nanoplates and rods with secondary nanowires in a comb-like arrangement. The nanoplates grow perpendicular to a central axis and have a six-fold symmetry. The hierarchical growth is related to the presence of Mg. Cathodoluminescence (CL) in the scanning electron microscope shows a blue-shift of the ZnO exciton peak as well as changes in the deep level bands due to the influence of Mg.
Technology of Fabrication and Morphology of Multiwalled Carbon Nanotubes on Co-Ni/MgO Catalysts by Thermal CVD
Authors: Ryu Ho Jin , Singh B.K. , Bartwal K.S. , Kityk Iwan V.
Published: March 2009

Multiwalled carbon nanotubes (MWNTs) were fabricated by thermal chemical vapor deposition (CVD) using monometallic and bimetallic Co and Ni on MgO as the catalyst. The mixture of H2/C2H2 gas was used as carbon source. The prepared CNTs have different sizes/shapes and morphologies with minimal formation of carbon particles. The maximum yield of CNTs was obtained with 50% Co catalyst at 600 oC. The morphology of the CNTs with 50% Co loading generates curved structure while 50% Ni results in the formation of linear structure with aligned graphene walls. Intensity ratio of D and G-peaks (ID/IG) was measured from Raman spectra. Scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) was done for the structural analysis of the prepared MWNTs.
Stability of Thin Gold Nano Wires
Authors: Verma Veena , Dharamvir Keya
Published: March 2009

Various gold nanowires with very small cross-sections (few atoms) have been studied using the Gupta potential. Gold nanowire icosa structure is found to be most stable among structures studied. The values of cohesive energy, Young’s modulus and shear modulus have been computed and all the values (except poisson ratio) are more than that of bulk gold. Another striking observation about gold nanostructures is that the Young’s modulus increases with tube radius whereas shear modulus decreases.
Synthesis and Characterization of Tin Oxide Nanoparticle for Humidity Sensor Applications
Authors: Krishnakumar T. , Jayaprakash R. , Singh V.N. , Mehta B.R. , Phani A.R.
Published: March 2009

Tin oxide nanoparticle was successfully prepared by the chemical digestion method from the starting material as SnCl2. The SnO2 material was characterized by X-Ray Diffraction (XRD), Transmission Electron Microscope (TEM) and Selected Area Electron Diffraction (SAED). The SnO2 was an n-type material preferred to humidity sensing property towards the moisture. The response and recovery time of sensor was calculated as 129sec and 206sec respectively. It has exhibited better efficiency compared with the bulk SnO2 material. Additional Weight loss, EDS, FT-IR and resistivity measurements were also presented.
Effect of Annealing in Atomic Hydrogen or Nitrogen Atmospheres on SiOx Nanoclusters Obtained by HFCVD
Authors: García-Salgado G. , Díaz-Becerril T. , Coyopol A. , Rosendo-Andrés E. , Juárez H. , Carrillo J. , Oliva A.I.
Published: March 2009

SiOx nanoclusters were obtained by Hot Filament Chemical Vapor Deposition using a quartz solid source and atomic hydrogen. The nanoclusters were characterized by Photoluminescence, Atomic Force Microscopy, Energy Dispersive Analysis X-ray and Fourier Transform Infrared Spectroscopy. FTIR and EDS characterization clearly show that the material is non stoichiometric silicon oxide with a composition that depends on the growth parameters, such as source-substrate distance and time of growth. Nanoclusters of SiOx presented photoluminescence with two principal peaks at around 859 and 920 nm. Photoluminescence intensity was enhanced when samples were annealed in hydrogen atmosphere and quenched when they were annealed in nitrogen atmosphere. However, it was observed that the same samples annealed once more with the initial atomic hydrogen conditions showed an increase in photoluminescence. From these results we suppose the photoluminescence produced in this material is influenced by deep level transitions associated with dangling bonds passivated with hydrogen on the surface of the Si crystallites embedded within SiOx nanoclusters.
Cooperative Pair Driven Quenching of Yb3+ Emission in Nanocrystalline ZrO2:Yb3+
Authors: Meza O. , Diaz-Torres L.A. , Salas P. , De la Rosa E. , Ángeles-Chávez C. , Solis D.
Published: March 2009

The concentration luminescence quenching of the NIR emission of Yb3+ in nanocrystalline ZrO2 is studied. It is found that the quenching is dominated by cooperative energy transfer processes from isolated Yb3+ ions to Yb-Yb pairs (Yb dimers). The Yb dimer concentration depends on the crystallite phase and size, which on time depends on Yb concentration. An extended energy transfer model was developed to predict the IR and cooperative visible fluorescence emissions by taking in to account the crystalline phase, the nanocrystals size, and the geometrical construction of Yb dimers. Our model succeeds to fit simultaneously both experimental VIS and NIR emissions, and the corresponding interaction parameters are reported.
Concurrent In Situ Formation of Ag / Ag2S Nanoparticles in Polymer Matrix by Facile Polymer-Inorganic Solid State Reaction
Authors: Waghmare Sujata , Shinde Manish , Gholap Ramkrishna , Koteswara Rao N. , Hawaldar Ranjit R. , Mulik Uttam , Amalnerkar Dinesh
Published: March 2009

We herein report the feasibility of polymer-inorganic solid-state reaction route for simultaneous in situ generation of Ag & Ag2S nanostructures in polymer network wherein an engineering thermoplastic, polyphenylene sulphide (PPS), itself acts as a chalcogen source as well as a stabilizing matrix for the resultant nanoproducts. Typical solid-state reaction was accomplished by simply heating the physical admixture of the two reactants i.e. AgNO3 and PPS by varying molar ratios mainly 1:1, 1:5, 1:15, 1:20, at the crystalline melting temperature (285 °C) of PPS. The synthesized nanoparticles were characterized by various physico-chemical techniques like X-ray Diffractometry, Scanning Electron Microscopy equipped with EDAX, Transmission Electron Microscopy and UV-Visible spectroscopy. The prima facie observations suggest the effective formation and subsequent entrapment of mainly nanocrystalline metallic silver (fcc) in PPS matrix for all the molar ratios chosen for the reaction. Additionally, simultaneous occurrence of nanocrystalline Ag2S (monoclinic phase) is also noticed in case of heated admixture of AgNO3: PPS with equimolar ratio. The TEM analysis reveals nanoscale polydispersity (5nm to 70nm) and prevalence of mainly spherical morphological features in all the cases with occasional indications of triangular and hexagonal morphological features depending upon the reaction molar ratio.
Hydrogen Storage in Nanostructured Mg-Base Alloys
Authors: Palacios-Lazcano A.F. , Luna-Sánchez J.L , Jiménez-Gallegos J. , Cruz-Gandarilla Francisco , Cabañas-Moreno J. Gerardo
Published: March 2009

Powders of elemental Mg, Zn, Al and Ag were milled in order to produce nanocrystalline alloys with nominal composition Mg98M2 (M=Zn, Al and Ag). Pure Mg was also mechanically milled without any additions. Single-phase nanocrystalline (crystal size 24-26 nm) Mg98M2 alloys were produced after 216 ks of milling. A passivity procedure was followed immediately after milling, by gradually exposing the alloy powders to air (~ 12 hrs). After this procedure, the mechanically alloyed powders were kept under argon atmosphere before being hydrided at 200 and 300 °C under 0.5 and 3 MPa P for 10 min. Previously milled (~ 1.5 years before) and passivated powder alloys (stored in air and referred to as “AE” samples) were also hydrided under the same conditions. No hydriding was observed in the as-received Mg powders (crystal size >> 100 nm), but the as-milled, passivated nanocrystalline alloys were partially hydrided (even the AE samples). The amounts of the MgH2 phase in the hydrided samples were larger in the Ar-stored than in the AE samples under all hydriding conditions. The possible role of MgO and Mg hydroxides, as well as of the alloying elements, on the hydriding behavior of the nanostructured, mechanically alloyed powder alloys is discussed.
Synthesis of Vertical ZnO Nanorods on Glass Substrates by Simple Chemical Method
Authors: Suresh Kumar P. , Yogeshwari M. , Dhayal Raj A. , Mangalaraj D. , Nataraj D. , Pal Umapada
Published: March 2009

ZnO nanorods (NRs) have been synthesized by a chemical bath deposition (CBD) method on simple glass substrate that had been precoated by successive ionic layer absorption and reaction (SILAR) with a thin ZnO film. ZnO NR array was obtained by using zinc acetate and hexamethylenetetramine as aqueous solutions at optimized pH concentration and deposition time. X-ray diffraction (XRD) and SEM analysis were used to confirm the growth of ZnO nanorods. The pH and deposition time of the solution was found to influence the growth behavior of ZnO NRs. PL analysis also reflected the growth behavior of ZnO NRs.
Proton Charge Transport in Nafion Nanochannels
Authors: Valenzuela Edgar , Gamboa S.A. , Sebastian P.J. , Moreira J. , Pantoja J. , Ibañez G. , Reyes A. , Campillo B. , Serna S.
Published: March 2009

The Nafion perfluorinated membranes are one of the best electrolytes used in the Proton Exchange Membrane Fuel Cell (PEMFC). Some methods have been used to study the electrical properties of Nafion; nevertheless, there are some aspects of the conduction process that are not well understood, such as the contribution of the bulk and the interfacial phenomena to the total proton conduction process. In this work the Electrochemical Impedance Spectroscopy (EIS) was employed in a four electrode system to study the protonic charge transport under conditions that simulate the operation of the PEMFC. Two Nafion membranes were evaluated to determine the relation of the activation procedure with the resistance to the protonic charge transference. The results are not only consistent with other measurements but also allow to separate the protonic charge transference process in two stages. Each stage was studied and their electrical parameters were calculated using Electrical Equivalent Circuits.
Formation of Amorphous and Nanostructural Powder Particles from Amorphous Metallic Glass Ribbons Using Ball Milling and Electrical Discharge Milling
Authors: Calka Andrzej , Wexler David , Bystrzycki J. , Oleszak Dariusz
Published: March 2009

In this paper both electric discharge assisted milling [1, 2] and conventional mechanosynthesis techniques were applied to investigate the effects of milling conditions on the fracture and agglomeration of amorphous CoSiB ribbons produced by planar flow casting. The effect of spark energy on particle shape and size produced by discharge milling was studied. Conventional milling in inert atmosphere for extended periods generally leads to the formation of porous powder particle aggregates, each particle comprised of small amorphous or, after extended milling times, nanocrystalline elements. The mechanism of agglomeration was believed to originate from repeated fracture, deformation and cold welding of individual ribbon
elements. In contrast to conventional milling, spark discharge milling was found to induce the formation of predominantly sub-micron single particles of amorphous powder. The morphology of individual particles varied from sub-micron irregular shaped particles to remelted particles, depending on selection of vibrational amplitude during discharge. For high vibrational amplitudes and high energy input a wider range of particles as produced. These included sub-micron particles, remelted particles and welded agglomerates, and nano-sized particles produced as a fume and collected during discharge milling under flowing argon. These results combined with observations that most re-melted particles produced by discharge milling were also amorphous confirmed that extremely high heating and cooling rates are associated with discharge milling of metals. They also confirm the potential of electrical discharge milling as a new route for the synthesis of ultrafine and nanosized powder particles from amorphous ribbon, for possible processing into 3-D shapes.
Processing Metals by Severe Plastic Deformation
Authors: Rosochowski Andrzej
Published: March 2009

Severe plastic deformation (SPD) is used to convert traditional coarse grain metals and alloys into ultrafine-grained (UFG) materials. UFG materials possess a number of improved mechanical and physical properties which destine them for a wide commercial use. However, any attempt to use SPD technology commercially requires a better insight into the mechanics and practicality of SPD processes. This paper looks into historical development of SPD processes and focuses on such aspects of SPD as material flow, role of hydrostatic pressure, friction, geometry of tools, billet and feeding considerations, technical feasibility, etc. The discussion of these topics sets a background for decisions concerning further research and commercialisation of SPD.
Electrophoretic Studies on Silicon Nitride: Traces of Silicates in UPW Shift Zeta Potential Similar to SC-1
Authors: Pfeuffer Alexander , Bensch Wolfgang , Lechner Alfred , Okorn-Schmidt Harald
Published: March 2009

In this paper we report on a new method of controlling the zeta potential of Si3N4 particles by addition of silicate traces to neutral ultra pure water (UPW). The positive zeta potential of Si3N4 at neutral pH shifts to negative values similar in alkaline pH solutions (e.g. with ammonia).
Application of HPLC for the Analysis of Organic Additives in Cleaning Chemicals and Cleaning Mixtures
Authors: Metzger S. , Kolbesen Bernd O.
Published: March 2009

The suitability of high performance liquid chromatography (HPLC) for the direct determination of the concentration of complexing agents for single chemistry cleaning is demonstrated. HPLC, coupled to a mass spectrometric detector (HPLC-MS) and two-dimensional mass spectrometry (MS/MS) have been applied for the investigation of the reactions involved in the decomposition of the complexing agents. The techniques described are useful for determining the stability of organic additives in wet chemical cleaning baths.
Single Backside Cleaning on Silicon, Silicon Nitride and Silicon Oxide
Authors: Broussous Lucile , Besson Pascal , Frank M.M. , Bourgeat D.
Published: March 2009

In this study, we used an SEZ single-wafer spin-processor to develop a single backside cleaning solution able to remove any metallic or exotic contaminants by etching a few angstroms of the wafer backside, whatever its coating (no coating, Si3N4 or SiO2). An H2O:H2O2:H2SO4:HF mixture was selected
because it allowed independent control of the etch rate on the 3 materials of interest,
without roughening to much the silicon surface. Chemistry efficiency was then
checked on wafers intentionally contaminated with various metals, and on “production wafers” contaminated during exotic materials
deposition or classical copper processes.
Surfactionated Rinse against Pattern Collapse and Defectivity in 193nm Lithography
Authors: Misat S.I. , Grozev G.G. , Versluijs J.J.
Published: March 2009

Recently, the reduction of pattern collapse in 193nm resists with the help of a surfactinated rinse has been widely reported in the literature [1-6]. This additional step was introduced between the DI rinse that follows the developer puddle, and the final dry spin step. The present work demonstrates that the latitude of 100nm, 90nm and 75nm dense line processes can be significantly extended with an appropriate surfactant rinse through pattern collapse reduction. Simultaneously, a considerable reduction of organic defectivity is reported on blanket resist wafers.
Variant Selection in Zr Alloys: How Many Variants Generated from one Beta Grain?
Authors: Barbéris Pierre , Montheillet Frank , Chauvy Cédric
Published: March 2009

The elastic energy of a set of the twelve variants generated during the b ® a transformation of zirconium, with volume fractions fi, i=1..12, is derived with simplifying assumptions and the conditions on the fi to reach the energy minimum are established analytically. The minimum number of variants needed to reach this minimum is shown to be 6, and in this case, the variants have very specific volume fractions. Another result is that the maximum volume fraction of any variant is 1/3.
Crystallographic Phase Composition and Structural Analysis of Ti-Ni-Fe Shape Memory Alloy by Synchrotron Diffraction
Authors: Sitepu H. , Brokmeier Heinz Günter , Chateigner Daniel , Wright J.P.
Published: March 2009

The preferred crystallographic orientation (i.e. texture) and the non-transformed austenite can cause serious systematic errors in the structural study of the R-phase in 50.75at.%Ti- 47.75at.%Ni-1.50at.%Fe (hereafter referred to as Ti-Ni-Fe ternary) shape memory alloy. The crystal structure refinement of R-phase synchrotron high resolution powder diffraction (SRD) data using Rietveld refinement with generalized spherical harmonic (GSH) description for preferred orientation correction showed that the sample consists of minor cubic phase and the space group was 3 P [1]. The objective of the present paper is to study the crystallographic phase composition and crystal structure refinement of SRD data of trigonal R-phase martensite and monoclinic (B19¢) martensite in Ti-Ni-Fe ternary alloy during thermal cycling using the GSH description.
Variant Orientation Distribution in a Near-γ Ti-Al Alloy with a Lamellar Microstructure
Authors: Dey S.R. , Morawiec Adam , Fundenberger Jean-Jacques , Hazotte Alain , Bouzy Emmanuel
Published: March 2009

An original approach based on semi-automatic treatment of Kikuchi patterns collected by Transmission Electron Microscopy is used to analyse the a2 an g variant distributions in a quaternary TiAl-based alloy (Ti-48at.%Al-2%Cr-2%Nb), with two lamellar microstructures of different fineness. Statistic data analysis shows that neither g variant orientations nor interface misorientations are randomly distributed within a given grain. The largest deviation from randomness is observed for the coarser microstructure. We also pointed out the presence of g|g subboundaries between same but slightly misoriented variants, as well as the existence of some semicoherent g|g twins accommodated by dislocation lattices. The analysis of the misorientation distributions of g|g and g|a2|g interfaces suggests that a variant selection occurs during growth and coarsening stages of the a ® a2 + g transformation process.
Grain Boundary Character and Pinning Effect during Grain Growth of Two-Phase Alloys
Authors: Guessasma Sofiane , Rouag N.
Published: March 2009

Monte Carlo technique was extensively used to simulate various recrystallization stages. In this study, the effect of second phase particles is studied in presence of varied populations of low and high angle grain boundaries. Results show that a significant pinning effect can be responsible for an abnormal growth when varying the population of low angle grain boundaries.
Neutron Diffraction Texture Analysis of Grain-Oriented Steel Sheets
Authors: Vratislav Stanislav , Dlouhá Maja , Kalvoda Ladislav
Published: March 2009

Our laboratory developed and tested experimental and calculation techniques for quantitative texture analysis based on the ODF combined with the diffraction of thermal neutrons. In our work the texture of the Fe-3%Si sheets was investigated after different stages of their processing, i.e. hot-rolled strips, first cold rolling, first inter-annealing, second cold rolling, second annealing and secondary recrystallisation. The texture experiments were carried out on the KSN-2 diffractometer which is equipped with the TG-1 texture goniometer with automatic data collection for transmission and reflection geometry. TODFND (the cubic symmetry of the crystals and orthorhombic symmetry of the specimen) was used and the ODF values were obtained together with all texture characteristics (pole figures, inverse pole figures, ODF - f (g) values, fibre texture with <110> and <001> axis parallel to rolling direction, parameters of the ideal orientations (HKL), texture index J, volume fraction coefficient f. The comparison of the texture parameters of the six samples with the different technologic history is given and the magnetic anisotropy of all measured samples was determined by means of the quantitative texture analysis (ODF-the matrix Cl nµ) for all samples. Results achieved in our study confirm that the quantitative texture analysis in connection with neutron diffraction can help to improve the technology of the preparation of oriented magnetic steel sheets.
A Sharp Cube Texture in Warm Rolled and Subsequently Annealed Silver Sheet
Authors: Zhang Zheng Rong , Sekine Kazuyoshi
Published: March 2009

In order to obtain a sharply cube textured silver sheet as the substrate for high
temperature superconductor (HTS) film with high Jc (critical current density), warm rolling combined with two step annealing treatment has been performed to clarify the perspective of texture formation in pure silver. Two kinds of starting material, which are silver ingots of commercial purity obtained by casting in air and vacuum, were used to examine the effect of oxygen on texture development. The main feature of warm rolling texture obtained in this study was a strong Brass {011}<211> component with minor S {123}<412> component, and in some cases, cube {001}<100> component or Copper {112}<111> component appeared also depending on the warm rolling procedures. Upon crystallization, {001}<100>, {124}<4,12,7> and {13,6,15}<365> orientations were formed as the dominant components in silver sheets and the relative amount of their orientation components depended on the concrete annealing conditions applied and on the oxygen content. A very sharp single-crystal like cube texture has been successfully realized in the specimen, which was cast in vacuum, warm rolled by 95 percent and subsequently annealed as 1500C×10 min-5000C×30 min in nitrogen. Finally, we discussed the technological basis on sharp cube texture formation in f.c.c. pure metals with low stacking fault energy.
A Rapid Deformation Texture Model Incorporating Grain Interactions: Application to Aluminium Hot Rolling Textures
Authors: Robert W. , Piot David , Guiglionda Gilles , Driver Julian H.
Published: March 2009

A simple and general new approach to predict deformation texture evolution during large plastic strains is presented. The stress in each grain, first calculated by a Taylor model, is then modified by the stresses of adjacent grains thereby making the local slip systems and lattice rotations neighbour dependent. Examples of texture simulations during hot rolling of aluminium alloys are given. The model predictions are compared with the standard Taylor model predictions and with ODF data of the textures measured during hot plane strain compression.
Modeling Texture Evolution during Rolling of Magnesium Alloy AZ31
Authors: Walde Tom , Riedel Hermann
Published: March 2009

Due to crystallographic texture rolled magnesium sheets exhibit strongly anisotropic and asymmetric plastic behavior. Therefore the simulation of texture evolution during manufacturing is a prerequisite for the prediction of the material properties. For this purpose we coupled the viscoplastic self-consistent (VPSC) model with the commercial finite element code ABAQUS/Explicit®. As magnesium sheets are usually produced by hot rolling the VPSC model was supplemented with a simple model for recrystallization. This model is able to describe the softening behavior of the magnesium alloy AZ31 during hot compression and allows us to simulate the development of the typical basal texture during hot rolling of this alloy.
Texture Investigations of Zircaloy-4 Tubes by Neutron Diffraction
Authors: Dlouhá Maja , Vratislav Stanislav , Kalvoda Ladislav
Published: March 2009

This article presents the results of texture investigations of Zircaloy-4 tubes. Neutron diffraction and inversion pole figures were used to chracterize the texture of samples. The main interest is given to the analysis of texture changes under different tensile test conditions including tensile force direction, annealing temperature and tensile test temperature. Four different specimens of different orientation to the tube axis were tested.
Local and Global Effects in Texture and Microstructure Observed after Channel-Die Compression of Copper Single Crystals and after Cross-Rolling of Copper Sheets
Authors: Pospiech Jan , Jasieński Zdzislaw , Ostafin M. , Schwarzer Robert A.
Published: March 2009

The change of the deformation path leads to destabilization of the substructure and affects the texture of the deformed metal. The observed changes of texture and microstructure are, as a rule, significant and their characteristics depend on the geometry of the deformation process. Previous investigations on copper (and copper alloy) samples after deformation by rolling and channel-die compression were based on X-ray pole figure measurements and on observations in the light microscope. Hereby only global texture and structural characteristics have been obtained. The present study is mainly based on measurements of individual crystal orientations performed by ACOM (Automated Crystal Orientation Measurement, “Automated EBSD”) in the SEM which enables a precise local analysis of the investigated phenomena.
For the channel-die experiments, (1 1 2)[1 1 -1] and (1 1 2)[1 -1 0] oriented copper single crystals have been used. After pre-deformation, a second deformation step has been carried out in transverse direction. The {1 1 2}<1 1 0> orientations are destabilized by channel-die compression, and clusters of layers develop which are composed of complementary {1 1 0}<1 1 2> components.
The deformation process in polycrystalline sheets after rotating the rolling direction leads again to a distinct disintegration of the microstructure and destabilization of the b fiber. This process of microstructure
reorganization after pre-deformation is fast and of high dynamics.
Temperature Dependence of the Texture of Sm-Co Thin Films
Authors: Tamm R. , Singh A. , Neu V. , Skrotzki Werner , Subba Rao K. , Oertel C.G. , Leinert S. , Fähler S. , Schultz Ludwig , Holzapfel B.
Published: March 2009

Hard magnetic Sm-Co thin films were prepared on Cr buffered MgO(001) single crystals by pulsed laser deposition. The texture of the films as well as the magnetic properties were measured for films deposited at different temperatures. Sm-Co is a system with high uniaxial magnetic anisotropy, where the c-axis is the axis of easy magnetization. Thin films of this material, with high coercivity and remanence, are of increasing interest for application in magnetic miniature devices. To explore the potential of this permanent magnetic material, a strong texture with a wellaligned c-axis is required. Analysis of several pole figures shows that mainly two types of orientations develop which grow epitaxially on Cr. For one orientation, the c-axis lies n the sample surface parallel to Cr(110). The c-axis of the second orientiation is tilted by 60° out of the surface plane.
Three-Dimensional Microstructure of Thin Copper Foils Revealed by Ion Beam Cutting and Electron Backscatter Diffraction (EBSD)
Authors: Simons G. , Kunze Karsten , Hauffe W. , Dual Jürg
Published: March 2009

Tensile testing of thin rolled copper foils with thickness ranging from 10 to 250 µm shows a dependence of the fracture strain with respect to the thickness of the foils [G. Simons et al., in Solid Mechanics and its Applications, Vol. 114 (2004), pp. 89-96]. To understand the influence of the microstructure in the foils on this phenomenon the microtexture is investigated by orientation mapping through electron backscatter diffraction (EBSD). As the samples are rather small standard preparation techniques do not apply. Two methods are described which allow the investigation of different section cuts of the samples: Cross sections of the samples were produced by ion beam cutting with a wide beam of 7 keV Kr ions. Internal planes parallel to the specimen surface were made accessible by wet etching. The as-received material possesses a very strong texture consisting mostly of the cube component and some remnants of a previous rolling texture. Specimens tested in a tensile test do not show major microstructural changes compared to virgin samples. After a heat treatment at 300°C the cube texture has significantly weakened in favour of revived rolling components, and the fracture strain increased about ten times relative to the as-is material.
Study of Error Distribution in Measured Pole Figures
Authors: Nikolayev D.I. , Lychagina T.A. , Nikishin A.V. , Yudin V.V.
Published: March 2009

Method to process neutron time of flight spectra for extracting texture information is suggested. Local peak fit is used to gain integral peak intensities as well as errors of fitted peak parameters. The usage of the method illustrated on spectra collected for Mg sample measured at Dubna on IBR-2 pulsed reactor at SKAT texture diffractometer. Reconstructed pole figures and corresponding errors are presented and discussed. It is important to underline that obtained errors are independent of the further method of pole figure processing.
Luminescence of ZrO2 Nanocrystals
Authors: Millers Donats , Grigorjeva Larisa , Łojkowski Witold , Opalińska A.
Published: March 2009

The luminescence of nanocrystalline tetragonal and cubic ZrO2 has been investigated. The tetragonal undoped ZrO2 revealed two luminescence bands, at ~2.0 eV and 2.7 eV , but only one band at ~2.7 eV was observed from cubic ZrO2. This luminescence was shown to be intrinsic. The regular zirconium-oxygen complex excited state is suggested as being responsible for intrinsic luminescence.
Lateral Size of Self-Patterned Nanostructures Controlled by Multi-Step Deposition
Authors: Szafraniak Izabela , Hesse Dietrich , Alexe Marin
Published: March 2009

Self-patterning presents an appealing alternative to lithography for the production of arrays of nanoscale ferroelectric capacitors for use in high density non-volatile memory devices. Recently a self-patterning method, based on the use of the instability of ultrathin films during hightemperature treatments, was used to fabricate nanosized ferroelectrics. This paper reports the use of the method for the preparation of PZT nanoislands on different single crystalline substrates - SrTiO3, MgO and LaAlO3. Moreover, a multi-step deposition procedure in order to control lateral the dimension of the crystals was introduced. The nanostructures obtained were studied by atomic force microscopy, scanning electron microscopy and X-ray diffraction.
Hydroxyapatite Growth on Glass/CdSe/SiOx Nanostructures
Authors: Pramatarova Lilyana , Pecheva Emilia , Nesheva Diana , Aneva Z. , Tóth Attila Lajos , Horváth Enikõ , Riesz Ferenc
Published: March 2009

The aim of this study was to find if nanocrystal layers obtained by well-established nanotechnology are able to induce deposition of hydroxyapatite [Ca10(PO4)6(OH)2]. It is known that nanosized objects and porous structures influence biological events and they may be used to create biologically integrated multifunctional devices including biomaterials and sensors. In this work, sequential physical vapour deposition of CdSe and SiO, or SiOx film was used to modify glass substrates. To study the ability of the nanostructured surfaces to induce hydroxyapatite deposition, samples were immersed in a simulated body fluid and simultaneously irradiated with a scanning laser beam for a few minutes. This resulted in a porous sponge-like non homogeneous hydroxyapatite layer, consisting of networks of aggregates of nano dimensions on the modified surfaces. Analysis showed higher Ca and P contents in the stripes of the laser-substrate interaction, which indicated the influence of the laser energy. The method of laser-liquid-solid interaction used has led to a synergistic effect due to the simultaneous use of the nanostructured substrate, aqueous solution and laser energy.
Spectroscopic Ellipsometry and Raman Studies on Sputtered TiO2 Thin Films
Authors: Karunagaran B. , Kim Young Kuk , Kim Kyung Hae , Dhungel S.K. , Yoo J.S. , Mangalaraj D. , Yi J.
Published: March 2009

Titanium dioxide films were deposited using DC magnetron sputtering technique onto silicon substrates at ambient temperature and at an oxygen partial pressure of 7×10 –5 mbar and sputtering pressure (Ar + O2) of 1×10–3 mbar. The composition of the films, analyzed by Auger Electron Spectroscopy (AES), revealed the stoichiometry with an O and Ti ratio of 2.08. The optical constants of the as-deposited TiO2 thin film were determined by Spectroscopic Ellipsometry in the photon energy range 1.2 to 5.5 eV at room temperature. The measured dielectric-function spectra reveal distinct structures at energies of the E1, E1+D1 and E2 critical points due to interband transitions. The Dielectric constant values were found to be substantially lower than those for the bulk TiO2. The dielectric related optical constants, such as the refractive index, extinction coefficient, absorption coefficient and normal incidence of reflectivity are presented and analyzed. The deposited films were calcinated at 673 and 773 K. The influence of post-deposition calcination on the Raman scattering of the films was studied. The existence of Raman active modes A1g, B1g and Eg corresponding to the Raman shifts are reported in this paper. The improvement of crystallinity of the TiO2 films as shown by the Raman scattering studies has also been reported.
CBN Composites with a Nanosized Binding Phase
Authors: Gorczyńska-Zawiślan Wioletta , Benko Ewa , Klimczyk Piotr
Published: March 2009

In this work cBN-TiN composites were studied. The composites were prepared by the HPHT technique (p=8 GPa, T=1750 0C). A TiN binding phase was used in two forms: as micro and nanomaterials. Thermodynamic calculations showed that formation of new phases in the cBNTiN composites was not possible in the experimental conditions which was confirmed by XRD investigations carried out. The surface morphology of nanocomposites was studied by scanning electron microscopy. The structure of these composites was compact; a TiN phase was uniformly distributed between cBN grains. Hardness was measured by the Vickers method using an indentation load of 9.81 N. The hardness of the investigated samples was dependent on the volume and grain size of the binding phase. Young's modulus of elasticity was determined, but its value was found to be dependent on the grain size of the TiN phase.
High-Pressure Induced Structural Decomposition of RE-Doped YAG Nanoceramics
Authors: Hreniak Dariusz , Gierlotka Stanislaw , Łojkowski Witold , Stręk Wiesław , Mazur P. , Fedyk Robert
Published: March 2009

The preparation of transparent nanoceramics from nanocrystalline Y3Al5O12 (YAG) powders doped with rare-earth ions has been described and the results of investigation of the structure and morphology have been presented. Decomposition of YAG nanocrystals into YAlO3 (YAP) was observed. The temperature and pressure for the decomposition was much lower than that reported for larger crystals. The transformation was connected with grain coarsening. The influence of the method of preparation of the YAG nanopowders on the final transparency of the nanoceramic produced was determined. Preliminary results of the dependence of luminescence properties on the structural transformation of the nanograins are presented.
Luminescence Properties of Neodymium-Doped Yttrium Aluminium Garnet Obtained by the Co-Precipitation Method Combined with the Mechanical Process
Authors: Caponetti Eugenio , Saladino Maria Luisa , Chillura Martino D. , Pedone L. , Enzo Stefano , Russu S. , Bettinelli M. , Speghini A.
Published: March 2009

Nanopowders of yttrium aluminium garnet Y3Al5O12 (YAG) doped with neodymium ions were obtained by the co-precipitation method from the reaction of aluminium and yttrium nitrate and neodymium oxide with ammonia. After washing and drying the hydroxide precursors were calcined at 500, 700, 800 and 900 °C for 1 hour and at 1000 °C for 3 hours. This product was treated by ball milling in a zirconia vial for 0.5, 1.5 and 10 h in order to achieve smaller nanoparticles. The structure, microstructure, morphology and optical properties were investigated by means of diffractometric, microscopic and spectroscopic techniques. The course of the amorphous-to-crystalline transformation was complete after calcining the powder for 1 hour at 900 °C. In the sample calcined for 3 hours at 1000 °C, the mean size of crystallite microdomains was reduced from 600 Å to 300, 250 and 160 Å after 0.5, 1.5 and 10 h of mechanical treatment respectively. The treated product was found to be contaminated with ZrO2. This contamination, from the vial and hardened ZrO2 balls reaches ca. 30 wt % after 10 h of mechanical treatment but causes only a slight reduction of the neodymium luminescence life-time, thus maintaining significant applicative properties.
Diamond-Like Carbon Formed by Plasma Immersion Ion Implantation and Deposition Technique on 304 Stainless Steel
Authors: Pakpum C. , Pasaja N. , Suanpoot P. , Boonyawan D. , Srisantithum P. , Silawatshananai C. , Vilaithong Thiraphat
Published: March 2009

Diamond-like carbon (DLC) films were deposited on stainless steel disc substrates by plasma immersion ion implantation and deposition (PIII&D) technique. Ar, CH4 and C2H2 gas were used as the working gases and discharged by radio frequency at 13.56 MHz. During the implantation and deposition process the plasma discharge was monitored by optical emission spectroscopy in order to analyze the state of the chemical species presented in the plasma. Ion implantation (Vbias = -20 kV and –10 kV) process served to produce a graded interface between the DLC films and the substrate material. Deposition (Vbias = -5 kV) process using a gas mixture of C2H2/Ar with a ratio of 1:1. The structure information of the DLC films was evaluated by Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). The composition of the DLC films and the thickness was measured by Rutherford backscattering spectrometry (RBS). The tribological properties were analyzed using a pin-on-disk tribometer and a microhardness tester, respectively. It was found that the DLC film was 0.8 μm thick with a hardness of 2.54 GPa and had good friction properties. Raman spectra appeared as G-band and D-band centered at 1550 cm-1 and 1418 cm-1, respectively. FTIR analysis observed the sp3 C=H2 asymmetric and sp2 C=C bond at 2928.73 cm-1 and 1667.10 cm-1 peak.