bluuebunny/crossref_metadata_2025 huggingface dataset:
Modified Method in Group Comparison Matrixes Consistency Check and its Application in Building Material Evaluation
Authors: Li Li , Wang Li Jiu
Published: April 2011

The comparison matrixes are obtained from decision makers might be contradictory, moreover an modified check method is proposed. Grey relational analysis (GRA) is adopted in group comparison matrixes consistency check for the first time. Firstly, the consistency indicators are put forward and are defined the definitions depending on GRA. Secondly, adjustment model is proposed to solve the group comparison matrixes inconsistency. Finally, the modified consistency check method are application in building material evaluation. It is believed that the proposed method is applicable to check consistency of building material evaluation.
Study on Compressive Strength of Fiber Reinforced Polymer Confined Concrete
Authors: Zhang Li Wen , Zhang Jun Ping , Sun Zuo
Published: April 2011

The study on compressive strength of fiber reinforced polymer confined concrete was conducted in this paper. Firstly, the general confinement mechanics was revealed, in which the confinement stress-σl, the restraint stiffness-El and the ultimate confinement stress-fl were proposed. Secondly, the influences of various parameters on compressive strength were analyzed by recent related studies and numerical simulation. The numerical simulation was carried out through the total of 27 finite element models under axial compressive load which were constructed by using software-ANSYS. Finally, the compressive strength model was set up by the dimension analysis and numerical regression.
Experimental Study on Adaptability of Artifactitious Aggregate with Water-Reducers
Authors: Li Chong Zhi , Niu Quan Lin , He Guang Ming
Published: April 2011

Two kinds of the representative artifactitious aggregates, namely the calcium-base and silicon-base, were chosen in the experimental study. Through analysis of SEM, it was found that the former’s main chemical component is calcium carbonate with a structure of crystal granules, the later might be a rock of silicon-base in a state of sandwich. Through experiments of the paste fluidity, ZETA potential and concrete test with different water-reducers, it was shown that the calcium-base aggregate, which could be easily used to prepare high workability and high strength concrete with the polycarboxylic water-reducer, bears a lower water-sobbing ability and has a well adaptability with any water-reducer, and that the silicon-base aggregate, a higher water-sobbing ability, a higher ZETA potential value of its powders, a bad adaptability that there might be a problem of producing HPC though using the high property polycarboxylic water-reducer.
Study on Effect of Carbonation Curing for Cement Minerals and Clinker
Authors: Ye Zheng Mao , Wan Li Hua , Liu Mei , Chang Jun
Published: April 2011

As an advanced technology, carbonation reaction could dispose of industrial solid residues and sequestrate CO2 gas, save resources and protect environment. In this study, Major minerals of cement were high-temperature burned using pure chemical reagents ( the burning temperature of C3S, C2S, C3A, C4AF were 1550°C,1400°C,1330°C, 1350°C). Forming and unforming main cement minerals and clinker were carbonated under the condition of CO2 partial pressure P=0.2MPa, T =25°C, CO2 gas concentration c>99.9% and water/soild w/s=0.12kg/kg. The change of minerals and the effect of carbonation were tested. The experimental results showed that carbonation reaction could been occured in four cement minerals (C3S, C2S, C3A and C4AF), and CaCO3 crystals appeared in these minerals. The sequence of carbonation degree of minerals were C3S﹥C2S﹥C4AF﹥C3A. 0.168g and 0.125g CO2 gas could been sequestrated by 1 gramme of C3S and C2S in carbonated curing respectively, and 0.1301g and 0.1464 g CO2 gas could been sequestrated by 1 gramme of formed and powdery clinker. After carbonated curing, clinker samples had high early strength and good soundness, 2h strength was 24.65 MPa and 3d strength was 41.65 MPa.
Properties of a Low-Carbon Cement with 90% of Industrial Refuse
Authors: Niu Quan Lin , Li Chong Zhi , Zhao Shu Qing
Published: April 2011

Material composition, mix proportion and physical properties of a low carbon cement with 90% of industrial refuse, properties of the cement was measured according to chinese national standard GB1346-2001 and GB175-2008. It is seen that the cement had good soundness, long setting time, low water requirement for standard consistency, good initial fluidity and high final strength as well, the properties are beneficial for the construction of highway engineering, underwater engineering and large volume concrete engineering.
Comparison of Fluidity between Metakaolin and Silica Fume Concretes
Authors: Wang Chong , Yang Chang Hui , Wan Chao Jun , Tian Yan Feng
Published: April 2011

Aiming at preparing the high performance concrete with metakaolin (MK) replacing silica fume (SF), comparison of fluidity between MK concrete and SF concrete was investigated in this paper. Slump, spread, and slump loss with time of fresh concrete under the condition of superplasticizer adding were tested, which containing with 5 to 15 wt. % replacement of MK, SF, combination of MK and ground granulated blastfurnace slag (GGBS), or combination of SF and GGBS, respectively. The mechanism for exploring fluidity difference of MK concrete and SF concrete were researched by measuring ζ potential and superplasticizer adsorption. The results indicate that concretes containing with 5 to 15 % MK were provided with better workability than concretes with SF. Fluidity of MK concretes incorporating with 5 to 15 % GGBS was better than that of SF concretes. Incorporating with 5 to 15% replacement, MK-cement-superplasticizer system present higher ζ potential, and lower superplasticizer adsorption than SF-cement-superplasticizer, which is an answer to why MK concrete has better fluidity than SF concrete. Physical filling effect of mineral additives is also is helpful to concrete fluidity.
Mechanical and Microstructural Properties of Cement Paste Incorporating Nano Silica Particles with Various Specific Surface Areas
Authors: Khaloo Ali Reza , Vayghan Asghar Gholizadeh , Bolhassani Mohammad
Published: April 2011

In this study, the effect of agglomeration and non-uniform dispersion of silica particles on the mechanical and microstructural properties of cement paste incorporating silica fume and nanosilica (NS) with various specific surface areas (SSA) is experimentally investigated. The SSA and replacement percent of silica particles were considered as test variables and four series of mixes were made including one set of mixes for silica fume with a SSA of 20 m2/g and three sets of mixes for three different types of NS with SSA equal to 90, 200 and 380 m2/g. In each series of mix designs three different cement replacement percents of 1.5%, 3% and 5% were applied. The results indicate that as the SSA and replacement percent of silica particles increase, the domain of variation of compressive strength results rises dramatically. It is observed that an increase in SSA of silica particles results in further agglomeration and difficulty in dispersion of NS particles within the paste. Also, there is significant variation on distribution of NS particles between similar specimens.
Experimental and FEM Analysis of the AA 6082 Processed by Equal Channel Angular Extrusion
Authors: León Javier , Luis-Pérez C.J. , Salcedo Daniel , Pérez Ivan , Fuertes Juan Pablo , Puertas Ignacio , Luri Rodrigo
Published: April 2011

Recent studies have shown that severe plastic deformation processes (SPD) improve the mechanical properties of the processed parts. Some of the most outstanding SPD processes are as follows: High Pressure Torsion (HPT), Repetitive Corrugation and Straightening (RCS), Cyclic Extrusion Compression (CEC), Accumulative Roll Bonding (ARB), Conform and Continuous Combined Drawing and Rolling (CCDR), among others, but the most well-known is Equal Channel Angular Extrusion or Pressure (ECAE/ECAP). The aim of these processes is to introduce high values of deformation inside the parts in order to reduce the grain size and thus to improve the mechanical properties of the starting material. The study of the damage imparted to an AA-6082 alloy is made in the present work. This alloy is received as cast and it is quenched at a temperature of 530 °C during 4 hours in order to be processed by ECAE at room temperature using different geometries of the dies. The imparted damage is also studied by using FEM simulations.
Generalized Maxwell Model as Viscoelastic Lubricant in Journal Bearing
Authors: Guemmadi M. , Ouibrahim A.
Published: April 2011

The hydrodynamic lubrication interest is still of great importance, so that more and more elaborated lubricants are considered. They, however, involve consequently more and more hydrodynamic complexity as a result of the rheological properties of the additives. In our case, we consider lubricants having viscoelastic properties described by a generalized Maxwell model used in the case of journal bearing lubrication. The complexity of the coupled associated equations (momentum and constitutive) to describe the hydrodynamic prevailing in such a geometry requires numerical solutions. Using the commercial Finite Volume software Fluent 6.3 together with an appropriate developed computational code, via UDF (User Defined Functions), we determine the pressure distribution as well as the flow velocity profile and the stress field in the core, the load bearing capacity developed and the attitude angle; all together with the effects of the viscoelastic lubricant parameters (relaxation time and shear viscosity).
Analysis of Chip Damage Risk in Thermosonic Wire Bonding
Authors: Dresbach Christian , Lorenz Georg , Petzold Matthias , Altenbach Holm
Published: April 2011

In current highly integrated microelectronic devices including system-in-package and stacked-die solutions, system reliability is strongly influenced by reliability of the gold and copper wire bond interconnections. Especially in state-of-the-art ICs containing mechanically sensitive low-K dielectric materials, controlling the mechanical properties of the free air ball (FAB) is of utmost significance due to chip damage risks during the bond process. Because of an extreme change in microstructure when forming the FAB, the material properties change significantly. Consequently, it is necessary to determine the properties of the FAB itself, when analyzing chip damage risks via finite element simulations. We present a micro-compression test that allows the determination of the hardening behavior of typical gold and copper FABs with diameters between 45 µm and 75 µm. In this test a FAB is placed on a diamond support or a test capillary and loaded by a diamond flat punch in a microindenter. The hardening was determined from force/displacement behavior via parameter identification using finite element simulations. The identified yield stresses correlate very well with the microstructure which was determined by electron backscatter diffraction method; this means that the yield stress decreases with increasing mean grain diameter in analogy to the Hall-Petch correlation. Compared to unprocessed wires the initial yield stresses are 50% to 60% lower. Considering these material properties, the damage risk during bonding on complex bond pad layouts can be predicted more realistically. This can be shown by results of real bond structures.
Femur Design Parameters and Contact Stresses at UHMWPE Hip Joint Cup
Authors: Fouad H. , Darwish S.M.
Published: April 2011

The contact stress that occurs in the ultra-high molecular weight polyethylene (UHMWPE) hip joint cup has been shown to be correlated with the implant wear rate. The wear of the hip joint is considered as one of the main factors that affect the long term performance of the implant. The contact stress that occurs in the UHMWPE hip joint cup is affected by the implant dimensions and materials. In this study, four different femur materials and geometries were used to investigate the effects of femur design parameters on the resultant contact stress on the UHMWPE cup. The results of the finite element (FE) simulation show that the contact stresses at the UHMWPE cup decreases dramatically with increasing the femur diameter. Also the results indicated that the contact stresses on the UHMWPE cup decrease significantly when using functionally graded (FG) femur with low modulus of elasticity. The presence of metal backing results in a slight reduction in the UHMWPE cup contact stresses especially for small femurs. Finally, the presence of a gap between the UHMWPE cup and the femur results in a remarkable increase in the cup stress especially for a small femur. The hip joint femur dimensions and materials are thought to play an important role in the transition of load in the implant and should be taken into consideration during the design of the hip joint.
Effects of Surface Active Element on the Biocompatibility of High Nitrogen Stainless Steel
Authors: Luo W.C. , Ke Y.L. , Lian Shuang Shii , Chu F.M.
Published: April 2011

Nickel-free high nitrogen stainless steel has become more important due to its impressive mechanical and corrosion properties. In contrast to high pressure processes, melting plasma in a normal atmosphere is an alternative way of obtaining high nitrogen content at low cost. However, melting in such an atmosphere will bring some surface impurities, like sulfur and oxygen, into the stainless steel through the refractories or the materials themselves. Therefore, this research aims the relationship between the sulfur and nitrogen content, and their influence on biocompatibility. Thermo-Calc is first used to design the composition of Fe-Cr based austenitic nitrogen stainless steel, and melted with different melting techniques, including plasma and an induction melting furnace. The results indicate that the nitrogen content varies with different sulfur content. It is also found that α-Fe (Ferrite) plates are observed near the grain boundaries when the sulfur content reaches a certain level. Besides, the Sulfur content has an obvious influence on the biocompatibility rather than nitrogen contents.
Modelling the Effects of Material Property and Dimension on the Heating of Silicon with Induction Directional Casting Furnace
Authors: Lian K.L. , Lian Shuang Shii , Chen Y.H. , Chu S.C. , Tsao Sheng
Published: April 2011

Directional Casting of silicon is a cost effective process to grow multi-crystalline Si ingots for wafers of solar cells. An appropriate melting process of polycrystalline silicon is closely related to the material properties and the size of graphite susceptors. These parameters have great influence not only on the melting temperature of silicon melt but also on the efficiency of induction heating, impurity distribution, dendrite and the direction of crystalline grains, which ultimately affect the properties of the solar cells. Therefore, in order to obtain good quality and energy efficiency of growth of polycrystalline silicon, one needs to know how the temperature fields relate to the processing parameters such as different sizes and properties of graphite susceptors in the furnace. In this paper, the influences of different properties such as density, electrical conductivity, thickness of graphite susceptor and cooling base-plate on the temperature of silicon with induction heating have been studied. To have an optimized control of processing parameters, a finite element-based software was used to simulate the temperature distribution of silicon melt in a polycrystalline vacuum induction refining furnace. The simulation takes into account the interaction of the induced eddy current and the heat transfer coupling in the vacuum induction furnace. Some of the modelling results are summarized as follows: 1. The material properties of the graphite susceptor have great influence on the temperature distribution. 2. The higher the operating frequency of the current, the sooner it reaches the melting temperature. 3. Base-plate made of stainless steel 304 performs better than the copper base-plate for the control of temperature distribution. 4. There exists an optimal thickness of the graphite susceptor, and the rise of temperature is not linearly proportional to the thickness of the graphite susceptor.
Microstructure and Mechanical Properties of Molybdenum Alloy Strengthened by Lanthanum Oxide and Silicon
Authors: Zhang Guo Jun , Zhao Yi , Li Bin , Wang Rui Hong , Lui Gang , Sun Jun
Published: April 2011

The molybdenum alloy sheets composite strengthened by silicon and lanthanum oxide were prepared by powder metallurgy technology with Mo-La2O3(0.3wt%) and Si(0, 0.1, 0.3wt%) powders and thermo-mechanically processing. The influences of silicon content on the microstructure and mechanical properties of the final molybdenum alloy sheets were tested and analysized. The results show that the addition of lanthanum oxide and silicon can refine the alloys grain size. The introduction of lanthanum oxide particles can increase the yield strength. Although the molybdenum alloys with 0.3wt% silicon have solid solution strengthening effect, the alloys with 0.1 wt% silicon exhibits obvious solid solution softening effect at room temperature. The strengthening mechanisms are quantitatively assessed, which well explain the increase or decrease in yield strength with respect to grain size, lanthanum oxide particle and silicon solid solution.
Effect of Carbon Migration on Sulfide Stress Corrosion Cracking Behavior of Dissimilar Joints in Wet H2S Environment
Authors: Jiang Yong , Gong Jian Ming , Yu Zheng Gang , Rong Dong Song
Published: April 2011

In this paper, mechanical performance test, slow strain rate test (SSRT) and optical microscopy analysis were employed in studying the effect of carbon migration on sulfide stress corrosion cracking (SSCC) behaviors of Cr5Mo/A302/0Cr18Ni9 dissimilar joints. The results showed that the resistance to SSCC of this joint improved first then decline after 98h aging treatments. Optical microscopy analysis showed fracture located in coarse grain heat-affected zone (HAZ) of as-welded joint, while in the joints aged for 56h and 98h, the fracture position transferred from coarse grain zone of HAZ to carbon rich belt in welds.
Effect of Activated TIG Flux on Performance of Dissimilar Welds between Mild Steel and Stainless Steel
Authors: Kuo Cheng Hsien , Tseng Kuang Hung , Chou Chang Pin
Published: April 2011

The purpose of the present work was to investigate the effect of oxide fluxes on surface appearance, weld morphology, angular distortion, and weld defect obtained with activated tungsten inert gas (TIG) process applied to the welding of 6 mm thick dissimilar metal plates between JIS G3131mild steel and SUS 316L stainless steel. The CaO, Fe2O3, Cr2O3, and SiO2 fluxes used were packed in powdered form. The results indicated that the surface appearance of TIG welds produced with oxide flux formed residual slag. TIG welding with SiO2 powder can increase joint penetration and weld depth-to-width ratio, and therefore the angular distortion of the dissimilar weldment can be reduced. Furthermore, the defects susceptibility of the as-welded can also be reduced.
Quench Brittleness of 12%Cr Martensitic Heat-Resistant Steel
Authors: Yang Gang , Liu Zheng Dong , Cheng Shi Chang , Yang Mu Xin
Published: April 2011

The mechanism of brittleness due to slow cooling during quenching was experimentally investigated in 12% Cr martensitic heat resistant steel. The mechanical property tests and microstructural characterization by SEM、TEM and XRD were conducted. The results showed the impact toughness would decrease with the slowing of cooling rate during quenching, and the low cooling rate within the temperature range from 820 to 660 °C played a significant effect on the impact toughness . Different from the mechanism of temper brittleness, the main causes of embrittlement due to the slow cooling upon quenching were both the continuous precipitation of M23C6 along prior austenite grain boundaries during the process of slow cooling and that of M2C along prior residual austenite film during tempering, and this kind of quench brittleness was nonreversal.
Gas Tungsten Arc Cladding of Titanium-Nickel Overlays onto the Carbon Steel and Stainless Steel for Cavitation Erosion Resistance
Authors: Chen J.M. , He Ju Liang , Chen K.C. , Chang J.T.
Published: April 2011

Gas tungsten arc welding with the TiNi intermetallic filler material was used to weld overlays onto the SUS 304 stainless steel and AISI 1045 medium carbon steel. The composition, hardness and cavitation erosion resistance of overlays on both kinds of steel was compared. The microstructure analysis results show that the elements from substrate materials diluted the overlay and caused the formation of dendrite structures in overlays. The crystalline phases in overlays on SUS 304 are TiNi-B2, TiNi-B19’, TiNi3 and Ti3Ni4, while those in overlay on AISI 1045 are TiNi-B2 and TiNi3. The multiple phase structures, precipitation of hard carbides and oxides formed in the overlays increases the hardness of the overlays 3-fold over the TiNi filler rod and steel substrate. This significantly increases the cavitation erosion resistance of substrate steels. The corrosion resistant overlays also enhance the cavitation erosion corrosion resistance of substrates in corrosive 3.5 wt% NaCl solution.
Microstructure, Mechanical and Electrochemical Properties of Arc Ion Plated Titanium Dioxide on Polyetheretherketone
Authors: Tsou Hsi Kai , Hsieh Ping Yen , Chi Meng Hui , Hung Yi Wen , Chung Chi Jen , He Ju Liang
Published: April 2011

The arc ion plating (AIP) technique is known to be capable of providing high film deposition rate and strong film adhesion. Titanium dioxide (TiO2) is characterized by its high chemical stability, photocatalysis and biocompatibility nature. The present study employed AIP to deposit TiO2 onto polyetheretherketone (PEEK) at low temperature. This study investigates the microstructure, mechanical and electrochemical properties of the TiO2 coatings as affected by the coating variables for some possible applications. The experimental results indicate that a crystallinic columnar film containing a controllable ratio of anatase to rutile phase can be prepared. The pencil hardness of the PEEK material graded as 4H was increased to over 9H by AIP-TiO2 coating. The film adhesion of the AIP-TiO2 coating can ultimately reach a critical load of 15 N and is associated with its deposition condition, but exhibits the cohesive failure mode (of the scratch scar) regardless of its deposition condition. The polarization behavior of the TiO2 coating in 3.5 wt.% NaCl electrolyte reveals that the AIP-TiO2 coating presents a greater electrochemical inertness if the rutile phase exists. The coating is, however, close to the electrochemical behavior of graphite material in all cases.
The Atomic Site Occupancies in the Fe-Cr σ-Phase
Authors: Kabliman Evgeniya , Ruban Andrei V. , Blaha Peter , Schwarz Karlheinz
Published: April 2011

The atomic site distribution of the complex σ-phase structure (P42/mnm) has been studied using density functional theory (within the EMTO and WIEN2k codes) applying the cluster expansion method in a mean field approximation at finite temperatures. We found that at low temperatures Fe atoms predominantly occupy the icosahedrally coordinated (A,D) sites, Cr atoms prefer the (B,E) sites with the high coordination numbers, while the C site remains mixed. However, at higher temperature close to 1000 K all occupations become more and more mixed and reproduce well the available experimental data.
Replacement of Vanadium by Ferrovanadium in Ti-Based BCC Alloys for Hydrogen Storage
Authors: Tousignant Manuel , Huot Jacques
Published: April 2011

Ti-based BCC solid solutions are promising hydrogen storage applications. Unfortunately, the application of these alloys in large scale is hindered by the high cost of vanadium. The solution of this problem may be to replace vanadium by ferro-vanadium (FeV). Here, we report our recent investigation of compositions TiV1-xMn1+x and Ti(FeV)1-xMn1+x where x = -0.2, -0.1, 0, 0.1, 0.2. Each composition was synthesized by arc melting. No subsequent heat treatment was performed. The alloys’ crystal structure in as-cast state and after hydrogenation was inspected by X-ray powder diffraction. We found that replacement of vanadium by ferrovanadium had the positive effect of destabilization of the hydride which makes it more useful for practical applications. Also even if the total hydrogen capacity was reduced, the reversible capacity could be improved. We found that replacement of vanadium by ferrovanadium drastically change the crystal structure of hydrogenated compounds.
Synthesis and Physical Properties of (NaxRE1-x)AlB14 (RE=Li, Mg, Rare Earths) Obtained by Molten Al Flux
Authors: Okada Shigeru , Kudou Kunio , Shishido Toetsu , Yubuta Kunio , Mori Takao
Published: April 2011

Single crystals of quaternary compounds in the solid solution (NaxRE1-x)AlB14 (RE=Li, Mg, rare earths (Tb, Dy, Ho, Er, Tm, Yb, Lu)) were grown by the Na-RE-Al-B system using a molten Al-self flux under an Ar gas. The single crystals of LiAlB14, NaAlB14, MgAlB14 and (NaxMg1-x)AlB14 (0.21≤x≤0) were grown; the quaternary boride (NaxLi1-x)AlB14 and (NaxRE1-x)AlB14 (Tb, Dy, Ho, Er, Tm, Yb, Lu) phases were not obtained at the single crystal growth experiment in the Na-Li-Al-B and Na-RE-Al-B systems. The as-growth LiAlB14, NaAlB14, MgAlB14, (Na0.08Mg0.92)AlB14 and (Na0.21Mg0.79)AlB14 single crystals were subjected to chemical analyses and measurements of unit-cell parameter. The homogeneity range for the solid solutions of (NaxMg1-x)AlB14 (0.21≤x≤0) crystals was studied by XRD and chemical analyses. Measurements of microhardness in air and magnetic susceptibility of crystalline samples of as-grown (NaxMg1-x)AlB14 (x=1, 0.21≤x≤0) have been measured in the temperature range of 300 K to 2 K.
Influence of Surface Active Substances on Magnetic Properties of Goethite Nanoparticles
Authors: Novakova Alla A. , Savilov Artem R. , Antonov A.N. , Gendler Tatiana S.
Published: April 2011

To receive monosized goethite (α-FeOOH) nanoparticles powders in the process of chemical precipitation of iron salt and alkali various surface active substances (SAS) with concentration of 0.3% were added to water: C12H25NaO4S (anion active), C12H38ClN (cation active) and EDTA – C10H14O8N2Na2 (complexon). It has been determined that the magnetic properties of the nanoparticles under investigation change in comparison with the nanoparticles obtained without SAS addition. In all the samples under study very interesting saturation magnetization temperature dependences have been obtained. They indicate the difference in goethite temperature phase transformations connected with various surface layers formed on the nanoparticles under SAS influence.
Structural, Superconducting and Magnetic Properties of La3-XRxNi2B2N3-δ with R = Ce, Pr, Nd
Authors: Ali Tahir , Bauer Ernst , Hilscher Gerfried , Michor Herwig
Published: April 2011

We report on structural and superconducting properties of La3-xRxNi2B2N3- where La is substituted by the magnetic rare-earth elements Ce, Pr, Nd. The compounds Pr3Ni2B2N3- and Nd3Ni2B2N3- are characterized for the first time. Powder X-ray diffraction confirmed all samples R3Ni2B2N3- with R = La, Ce, Pr, Nd and their solid solutions to crystallize in the body centered tetragonal La3Ni2B2N3 structure type. Superconducting and magnetic properties of La3-xRxNi2B2N3- were studied by resistivity, specific heat and susceptibility measurements. While La3Ni2B2N3- has a superconducting transition temperature Tc ~ 14 K, substitution of La by Ce, Pr, and Nd leads to magnetic pair breaking and, thus, to a gradual suppression of superconductivity. Pr3Ni2B2N3- exibits no long range magnetic order down to 2 K, Nd3Ni2B2N3- shows ferrimagnetic ordering below TC =17 K and a spin reorientation transition to a nearly antiferromagnetic state at 10 K.
New Ferromagnetic Chromium Chalcogenides, ACr5Te8 (A = K, Cs and Rb)
Authors: Yamazaki Satoshi , Ueda Yutaka
Published: April 2011

New pseudo-hollandite chromium tellurides, ACr5Te8 (A = K, Cs and Rb), have been synthesized. KCr5Te8 is isostructural (type-A; space group C2/m) to ACr5S8, while RbCr5Te8 and CsCr5Te8 crystallize in a different structure (type-B; space group C2/m). All compounds show ferromagnetic transition, in contrast to antiferromagnetic transition in pseudo-hollandite chromium sulfides and selenides. The ferromagnetism of ACr5Te8 would be related to long Cr-Cr distances, band structure or itinerancy.
Hybridized Electronic States in Dense Intermetallics as Studied by ESR
Authors: Ivanshin Vladimir A. , Litvinova T.O. , Sukhanov A.A. , Ivanshin N.A. , Endeward B.
Published: April 2011

We review electron spin resonance (ESR) experiments in several concentrated Yb-, Ce-, and Eu-based intermetallic systems. Recent theoretical studies attribute well resolved ESR signals with hybridization effects between 4f and conduction electrons (CE) in the presence of ferromagnetic (FM) fluctuations. We believe that the ESR absorption is caused here by a novel type of ESR excitations – hybridized electronic states, which are created in some strongly correlated electronic systems due to hybridization between the 4f-orbitals and the wavefunctions of the CE of the outer d, s, and p shells in conjunction with FM RKKY interaction.
Magnetic Properties and Magnetocaloric Effect in Selected MM’X-Type (M, M’ = 3d or 4d Metal, X = As, P, Ge) and Mn1-xTxAs-Type (T = 3d Metal) Intermetallics
Authors: Zach Ryszard , Chajec Wiesław , Toboła Janusz , Fruchart Daniel , Hlil El Kebir , Balli Mohamed , Wolfers Pierre
Published: April 2011

In this report a review of magnetic properties of two groups of intermetallic compounds in relation with their magnetocaloric effect properties is presented. A first group of materials concerns the MM’X type (M, M’-metal 3d or 4d, X = As, P, Ge) of compounds. In this group the MnRh1-xCoxAs and MnFe1-xCoxP series of solid solutions are investigated. In a second group of materials, the Mn1-xTxAs (T = Cr, V, Ti, (Ti0.5V0.5) ) series of compounds are analyzed. In this case a special attention is paid for high dc field magnetization measurements and for selected compounds. As a summary the magnetic entropy change vs. M, M’ or T transition metal concentration for F-P phase transitions will be shown. Furthermore results of KKR-CPA electronic band structure computations in relation to magnetic properties are discussed.
Particularities of Structure and Stability of Cationic-Ordered Layered Titanates
Authors: Zvereva Irina , Sankovich Anna , Missyul Alexander
Published: April 2011

Thermal stability of the layered titanates NdMTiO4 and Nd2M2Ti3O10 (M=Na, K) featured with 1 or 3 perovskite layers has been investigated in thermal annealing at 780 – 1400°С. Their structure variations are monitored using thermal analysis (TGA, DTA), X-ray powder diffraction, and scanning electron microscopy. Judging from the decomposition sequence and the stable temperature range for individual phase, the structure of Nd2M2Ti3O10 with three perovskite layers is identified most stable among these layer titanates. As a whole, the K-containing phases are less stable than the Na-containing ones.
The Ln- and Mn-Substituted Aurivillius Phases: Formation Mechanism and Physical Properties
Authors: Missyul Alexander , Zvereva Irina , Khayrullina Evgeniya
Published: April 2011

The Aurivillius phases [Bi2O2][An-1BnO3n+1] are well-known ferroelectrics with high Curie temperatures. Recently this class of compounds attracted significant attention due to possible multiferroic and photocatalytic properties. We have investigated the possibility of the Bi→Ln and Ti→Mn substitution in the double-layered Aurivillius phases Bi3NbTiO9 and Bi3TaTiO9. In both cases substitution appeared to be limited. The Ln-substituted compounds can be obtained only for Ln=La-Gd. The Ti→Mn substitution is possible only if the substitution degree does not exceed 0.2. The formation of the double-layered Aurivillius phases has been investigated by means of the X-ray diffraction and thermal analysis. The limits of substitution have been explained on the basis of the formation mechanism. The stability of the intermediate Bi4Ti3O12-based phase appeared to be crucial for the possibility of obtaining the substituted Aurivillius phase. The temperature dependence of the dielectric and magnetic properties has been investigated. The magnetoelectric coupling is found at low temperatures.
Structural Reinvestigation of Alkali Hexatitanate
Authors: Kataoka Kunimitsu , Kijima Norihito , Hayakawa Hiroshi , Akimoto Junji
Published: April 2011

Na1.614Li0.386Ti6O13 Single crystal was synthesized by a Li+ ion-exchange method from Na2Ti6O13 single crystal in a molten salt of LiNO3. The obtained Na1.614Li0.386Ti6O13 single-crystal is colorless and has the shape of a rod. Na1.614Li0.386Ti6O13 crystallizes in the monoclinic tunnel type structure, space group C2/m, and lattice parameters a = 15.144(2) Å, b = 3.7492(5) Å, c = 9.162(2) Å and β = 99.0131(9)º. The structure was determined by a single-crystal X-ray study and refined to the conventional values of R = 0.0247 and wR = 0.0451 for 969 independent observed reflections.
Magnetic Field Effects in Antiferromagnetic CePd3In2
Authors: Strydom André M. , Britz Douglas
Published: April 2011

We present results of specific heat and magnetic susceptibility measurements as function of temperature and magnetic field on the rare-earth compound CePd3In2. Known to order antiferromagnetic below 2.1 K, we discuss the influence of magnetic field on the stability of the magnetic order.
Enhanced Thermoelectric Figure of Merit in P-Type DDy(Fe1-XCox)4Sb12
Authors: Rogl Gerda , Grytsiv Andriy , Rogl Peter , Bauer Ernst , Zehetbauer Michael
Published: April 2011

Thermoelectric (TE) properties of skutterudites DDy(Fe1-xCox)4Sb12 for 0.2  x 0.3 were studied in the temperature range from 300 K to 800 K and compared with values for x = 0. Didymium (DD, 4.76 mass % Pr and 95.24 mass % Nd) was used as natural double filler. At Co-concentrations 0.225  x  0.25 maximum TE-performance was obtained with impressive power-factors (4.5 mW/mK2) and ZTs (ZT1.2 at 700 K). Furthermore these skutterudites maintain the high ZT over a broad temperature range providing an excellent p-leg for high-efficiency thermoelectric power generation.
Bulk Transition Elements Based Materials for Magnetic Cooling Application
Authors: Balli Mohamed , Sari Osmann , Zamni L. , Robert A. , Forchelet J. , Fruchart Daniel
Published: April 2011

In this paper we investigate the performances of two bulk magnetocaloric refrigerants based on La(Fe,Co)13-xSix and prepared by powder metallurgy. Both materials were developed especially for a magnetic cooling machine. We have determined the magnetocaloric effect in term of temperature change under magnetic field using a test-bench with practical running conditions. ΔT was measured under 2 T and close to room temperature range. The obtained results will be compared with those of some reference materials reported in the literature. In addition, a composite material based on La(Fe,Co)13-xSix is proposed for magnetic systems using Ericsson and AMR cycles for refrigeration close to room temperature.
Crystal Structure Analysis of the Mg2Si1-xSnx System Having Potential Thermoelectric Properties at High Temperature
Authors: Boudemagh D. , Fruchart Daniel , Haettel R. , Hlil El Kebir , Lacoste A. , Ortega L. , Skryabina N.E. , Toboła Janusz , Wolfers Pierre
Published: April 2011

Laves phases of C15 type of the system Mg2Si1-xSnx with x = 0, 0.4, 0.6 and 1 were synthesized in polycrystalline state in tantalum ampoule heated by high frequency coupling. The as-cast materials were analysed first at room temperature by X-ray diffraction (XRD). Systematically, XRD patterns were recorded up to 700 °C and Differential Scanning Calorimetry analysis was performed up to 1200°C to control the chemical and structural phase transformations. From these experiments, a C15 to C36 structure transformation was pointed out around 600°C in Mg2Si1-xSnx.solid solutions.
Clusterization Phenomena and Magnetic Phase Transitions in Rare Earth Intermetallics
Authors: Rojas D.P. , Marcano N. , Gómez Sal J.C.
Published: April 2011

Two cases of anomalous phase transitions in Ce intermetallics are presented. In CeIn2 multiple signatures of a first order paramagnetic-ferromagnetic transition at 22 K have been experimentally detected. We discuss possible mechanisms for such behaviour and the new studies in the La1-xCexIn2 series. In the he case of CeNi1-xCux the low temperature ferromagnetic long range order appears owing to a magnetic cluster percolation process, from a cluster glass state established above the ferromagnetic state.
Interpretation of the Magnetic Order, Neutron Diffraction and 111Cd PAC Studies of NdScGe
Authors: Cadogan J.M. , Ryan D.H.
Published: April 2011

NdScGe is a ferromagnet with TC = 194(2) K. The magnetic moments of the Nd substructure order along the tetragonal c-axis just below TC and undergo a gradual canting away from the c-axis upon cooling, commencing at around 165 K. We used neutron powder diffraction to show that the Nd magnetic moments lie 70(3)o off the c-axis at 4 K [1]. The apparent discrepancy between our neutron diffraction results and those obtained using PAC [2] (a canting angle of around 32o just below TC , increasing to 45o at 25 K) can be reconciled by placing the principal axis of the electric field gradient tensor in the tetragonal basal plane, rather than along the c-axis, as assumed in the PAC analysis. The unusual temperature dependence of the 111Cd PAC quadrupole frequency at the Sc site, which was interpreted in terms of a lattice softening occurring near the Curie temperature, is shown to be a consequence of the fact that one cannot determine the sign of the quadrupole frequency from a PAC experiment. Finally, we show that the Nd magnetic moments in the canted regime have a [110] basal component rather than [100].
Study of Hydrogen in Hf7Ni10 Combined with TiV0.8Cr1.2 by PAC
Authors: Gil J.M. , Costa Benilde F.O. , de Rango Patricia , Fruchart Daniel , Miraglia Salvatore , Skryabina N.E.
Published: April 2011

Perturbed Angular Correlation (PAC) measurements were performed at room temperature on samples of Hf7Ni10 and of Hf7Ni10 combined with TiV0.8Cr1.2, and at temperatures in the range from 17 K to 350 K in a concentrated hydride of the combined alloy. The PAC results show that the Hf7Ni10 intergranular phase becomes amorphous in the combination process. The results for the hydride composite show in the Hf7Ni10 phase the formation of a stable interstitial hydrogen state below 100 K and a smooth rearrangement of the hydrogen atoms position above 100 K,corresponding to a slow diffusion movemnet of a short-range nature. A second phase transition is observed at around 300 K, presumably to aphase precursor of the hydrogen desorption of the hydride.
Preparation and Properties of Ultra-High Temperature Ceramics Based on ZrC and HfC
Authors: Brozek Vlastimil , Ctibor Pavel , Cheong Dong Ik , Yang Seong Ho , Mastny Libor , Novák Michal
Published: April 2011

Successful preparation of massive compact bodies from ultra-high temperature ceramics like zirconium carbide, hafnium carbide and their cermets with tungsten matrix with high values of mechanical parameters is difficult. Only limited number of techniques is able to perform it because of their absolutely highest melting points. In our contribution the preparation of these materials by both - hot pressing and plasma spraying techniques is described and chemical processes taking part at the fabrication are studied. Hot-pressed products fabricated at 2000°C and 6 GPa partly react with the internal surface of the BELT-type apparatus. Melting and solidification is taking place at plasma spraying. This process, carried out by water stabilized plasma torch with centerline temperature up to 30 000°C, is joined with undesirable reactions with plasma-forming medium, with oxidation in a turbulent plasma flow and nitridation of free-flight particles. All these chemical processes depend on variety of parameters, such as particle size of the feedstock powders or electric power of the arc. The mentioned parameters are easily controlled. Other, less controllable, factors include trajectory of powder particles in the plasma jet, important for the melting degree as well as for oxidation or nitridation of the powder surface. New knowledge concerning properties of compact ZrC and HfC were obtained.
Synthesis and Electronic Properties of TlFe2Se2-δ
Authors: Horiguchi Satoshi , Sato Hirohiko , Umeyama Norio , Hara Yoshiaki , Miyakawa Nobuaki , Takase Kouichi , Ikeda Shinichi
Published: April 2011

TlFe2Se2-δ was synthesized by a self-flux method with excess amount of selenium. Elemental analysis using energy-dispersive X-ray spectroscopy estimates the deficiency δ at about 0.5. The magnetic susceptibility reveals an antiferromagnetic transition at TN ≈ 475 K. The resistivity exhibits a semiconducting behavior with an activation energy, EA = 0.04 eV. There is a clear anomaly in the resistivity at TN, indicating a strong interplay between magnetism and electric conduction.
Electrical Resistivity Anomalies in SbxVyMozOt Phases
Authors: Groń Tadeusz , Filipek E. , Duda Henryk , Mazur S. , Bärner K.
Published: April 2011

Electrical resistivity dips in the temperature range 269-287 K and n-type conductivity below 415 K for solid solutions of MoO3 in SbVO5 with general formula SbxVyMozOt are observed. The electrical resistivity anomalies are interpreted as due to conduction of small-polarons, generated here as electrons together with distortions of their associated defective oxygen lattice and/or alternatively based on the crossover of electronic or polaronic states.
Specific Heat of CeRhSb Doped with Pd
Authors: Ślebarski Andrzej , Fijałkowski Marcin
Published: April 2011

CeRhSb is known as a Kondo insulator with a hybridization gap Eg/kB  7 K. By doping CeRhSn with Pd this gap is strongly reduced and completely removes for x>0.08 in the system of CeRh1-xPdxSb alloys. The specific heat C of the samples 0x0.08 shows the heavy-Fermi-like behavior in the form of an strongly enhanced Sommerfeld coefficient CTT, which follows below 8 K a power law over a decade in temperature. Our measurements suggest that the enhanced  value originates from correlated, residual in-gap states at the Fermi level.
Magnetic and Related Properties of Tb4Sb3 Compound
Authors: Ivanova T.I. , Nikitin S.A. , Morozkin A.V. , Tskhadadze G.A. , Mulak J. , Pikul A. , Suski Wojciech , Badurski D. , Wochowski K.
Published: April 2011

An X-ray phase analysis and the metallographic examination were employed in the investigation of crystal structure of the Tb4Sb3 compound. Magnetic properties have been studied by means of magnetometric measurements, including a magnetocaloric effect, electrical resistivity and magnetoresistivity, and specific heat in broad temperature and the magnetic field ranges on a polycrystalline sample. It was confirmed that the Tb4Sb3 compound is an antiferromagnet with the temperature of the magnetic transition, TN = 111.4 K (specific heat) or 114 K (magnetization) . The results are discussed in the term of a crystal field splitting scheme.
Electronic and Magnetic Properties of Ternary Stannides RERhSn (RE = Tb, Dy and Ho)
Authors: Łątka Kazimierz , Gurgul Jacek , Pacyna Andrzej W. , Pöttgen Rainer
Published: April 2011

The results of magnetic studies and Mössbauer investigations made with 119Sn source are reviewed for the series of RERhSn (RE = Tb, Dy and Ho) compounds crystallizing in the same hexagonal ZrNiAl-type of structure. The role of crystalline electric field effects in the establishing of magnetic moment orientations observed in these compounds and their influence on the observed magnitudes of magnetic moments are discussed.
Growth and Characterization of Well-Aligned RuO2/R-TiO2 Heteronanostructures on Sapphire (100) Substrates by Reactive Magnetron Sputtering
Authors: Hsu Hung Pin , Huang Ying Sheng , Yeh Chien Nan , Chen Yi Min , Tsai Dah Shyang , Tiong Kwong Kau
Published: April 2011

We report the growth of well-aligned RuO2/R-TiO2 heteronanostructures on sapphire (100) substrates by reactive magnetron sputtering using Ti and Ru metal targets under different conditions. The surface morphology and structural properties of the as-deposited heteronanostructures were characterized using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected-area electron diffractometry (SAED). The FESEM micrographs and XRD patterns indicated the growth of vertically aligned RuO2(001) nanotubes and twinned V-shaped RuO2(101) nanowedges (NWs) on top of R-TiO2 nanorods under different sputtering pressures. TEM and SAED characterizations of the V-shaped RuO2 NWs showed that the NWs are crystalline RuO2 with twin planes of (101) and twin direction of [ 01] at the V-junction.
Neutron Diffraction Study of the Kondo Systems Ce6Ni1.67Si3 and Ce5Ni1.85Si3
Authors: Tencé Sophie , Gaudin Etienne , André G. , Chevalier Bernard
Published: April 2011

Neutron powder diffraction experiments were performed on the moderate Kondo systems Ce6Ni1.67Si3 and Ce5Ni1.85Si3. These measurements have shown that Ce6Ni1.67Si3 does not present a long range magnetic order down to 1.6 K, but only short range ferromagnetic correlations. Ce5Ni1.85Si3 undergoes an antiferromagnetic transition at TN ≈ 6 K. Its magnetic structure at 1.5 K and zero field is collinear with the magnetic moments along the hexagonal axis and can be described with the propagation vector k = (1/2 0 0). This antiferromagnetic order coexists with a short range ferromagnetic component.
Superconductivity in Fluorine-Arsenide Sr1-xNdxFeAsF
Authors: Suganuma Ryosuke , Watanabe Tadataka , Takase Kouichi , Takano Yoshiki
Published: April 2011

We have successfully prepared the new family of fluoride-arsenide Sr1-xNdxFeAsF (0 ≤ x ≤ 0.5), and investigated the electrical and magnetic properties. Sr1-xNdxFeAsF with x = 0.4 and 0.5 show superconductivity, and their superconducting transition temperatures are 32 and 49 K, respectively. The superconducting volume fractions of Sr0.6Nd0.4FeAsF and Sr0.5Nd0.5FeAsF are ~11 and ~ 17 %, respectively. On the other hand, the sample of Sr1-xNdxFeAsF (0 ≤ x ≤ 0.35) is not superconducting but shows a metallic conductivity. All compounds show a weak ferromagnetism with the Curie temperature of above room temperature. The origin of the ferromagnetism may be due to the tiny Fe impurity.
Phase Relation of FeS2-VS2 System and New Phase of Defect Troilite Structure
Authors: Miyata Yoshihisa , Hayashi Koya , Sakane Genta , Arimoto Takaaki , Katayama Yasuhiro , Shimakawa Mamoru
Published: April 2011

A large defective troilite (Fe0.9V0.1)0.82S is prepared by a sealed silica-tube method at 800oC and characterized by a powder X-ray diffraction method and using a magnetic property measurement system. The crystal structures of a defective troilite and non defective troilite are analyzed by Rietveld method. The large defect enhances the Fe-Fe pairing and suppresses the waving of Fe-chain along c-direction. The antiferromagnetic property is observed on both troilites. The spin-flip transition temperature of the large defective troilite is 9K.