bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flux Synthesis of New Multinary Bismuth Chalcogenides and their Thermoelectric Properties
Authors: Chung Duck-Young , Choi Kyoung-Shin , Brazis Paul W. , Kannewurf Carl R. , Kanatzidis Mercouri G. 
Published: April 2011

AbstractWe present the synthesis and structure of the new chalcogenide compounds, Rb0.5Bi1.83Te3, APb2Bi3Te7 (A = Cs, Rb), K1.25Pb3.50Bi7.25Se15 and A1+xPb4−2xSb7+xSe15 (A = K, Rb). The layered structures of the first two telluride compounds are related to each other in a very interesting fashion. These compounds are n-type metallic conductors and solid solutions with Se and Sb have also been synthesized. K1.25Pb3.50Bi7.25Se15 and its Sb analogs have a complex three-dimensional structure composed of NaCl- and Bi2Te3-type building units. The thermal stability, melting behavior, electrical conductivity and thermopower of these compounds are reported.
Mechanical properties of SU-8
Authors: Mcaleavey A. , Coles G. , Edwards R. L. , Sharpe W. N. 
Published: April 2011

AbstractAn existing test system for recording the stress-strain curves of metal microspecimens has been used to measure the strength of the ultrathick photoresist SU-8. The microspecimens are 3 mm long with a gage section 0.2 mm wide. The SU-8-25 specimens were 0.08 mm thick with an average strength of nearly 120 MPa, and the SU-8-50 specimens were 0.125 or 0.145 mm thick with an average strength of 130 MPa. Measurements of Young's modulus proved difficult, but a preliminary value of 3 GPa was obtained.
Characterization of Transparent Conducting Pulsed Laser Deposited Films in the Indium Zinc Oxide System
Authors: Rougier A. , Naghavi N. , Marcel C. , Portemer F. , Dupont L. , Guéry C. , Tarascon J.M. 
Published: April 2011

AbstractThin films of indium zinc oxide so called IZO were prepared with pulsed laser deposition. It was found that the crystalline structure, the composition and the morphology of the films as well as the optical and electrical properties were quite sensitive to the deposition conditions namely to the temperature and oxygen pressure. The crystallinity of the ZnkIn2O3+k (k from 1 to 5) thin films increases as the substrate temperature increases. An average transmittance of 85 % in the visible region was obtained for any k values. Optical measurements show a continuous decrease of the band gap as the zinc amount increases. The highest conductivity reported is for the ZnIn2O4, thin films deposited at 300 °C (σ = 1.2 103 S/cm). Increasing the amount of Zn (i.e. k value) was found to result in a conductivity decrease. Finally, a good correlation between the electric mobility and the optical mobility is obtained.
A Neutron Diffraction Study of Co2Ru1-xMnxO4 Spinels
Authors: Mandrus D. , Keppens V. , Chakoumakos B. C. , Granroth G. E. , Nagler S. E. 
Published: April 2011

AbstractPowder neutron diffraction and magnetization measurements are presented on the Co2Ru1-xMnxO4 system. In these materials the tetrahedral (A) sites are occupied by Co2+ (S = 3/2) ions, and the octahedral (B) sites are jointly occupied by Co3+ (low spin, S = 0), Ru3+ (low spin, S = 1/2), and Mn3+ (S = 2) ions. The measurements reveal that Co2RuO4 undergoes a spin-glass transition, Co2MnO4 is a collinear ferrimagnet, and that Co2Ru0.5Mn0.5O4 undergoes an unusual magnetic double transition. Triple-axis measurements indicate that the lower temperature transition in Co2Ru0.5Mn0.5O4 is characterized by the onset of diffuse scattering and the emergence of short-range order. The Co2Ru1-xMnxO4 series appears to be well-suited for studying the coexistence of long- and short-range magnetic order.
Plutonium Pyrochemical Salts Oxidation Using Vanadium Oxide
Authors: Smith Donna M. , Neu Mary P. , Garcia Eduardo , Dole Vonda R. 
Published: April 2011

AbstractThis paper presents results from the oxidation of PuCl3 with two-thirds, one, and two equivalents of V2O5 and the oxidation of Pu° with two and three equivalents of V2O5. All of the PuCl3 reactions were successful in that little or no starting materials remained and the major plutonium reaction product was PuO2. There is no evidence that V is reduced to V(II) or V°. According to powder XRD analysis, the bottom layers of all three reactions are identical, the middle layers contain different phases, and phases in the top layer of the oxidation with one equivalent of V2O5 is contained in the top layer from the oxidation with two-thirds equivalent of V2O5. The Pu° oxidations are more complex than the PuCl3 oxidations. More unreacted Pu° remains in the reaction using three equivalents of V2O5 than the reaction using two equivalents of V2O5. The lack of predictability of these reactions may be a result of the source of Pu° used in our experiments. The presence of soluble Pu(III) and the relative absence of PuO2 in all the Pu° reactions suggests V2O5 does not oxidize Pu° to Pu(IV) under these conditions. Chlorine is detected in the off-gas of the Pu° oxidations, indicating the salt matrix participates in the reaction.
The Bismuth-Barium Oxides
Authors: Müller K. , Meen J.K. , Elthon D. 
Published: April 2011

AbstractPhase relations have been determined for the Bi-Ba oxide pseudobinary up to 50 cat % Ba in 1 atm of oxygen at 640°-1000°C. The low-temperature α-Bi2O3 polymorph does not dissolve appreciable BaO. All other phases in the system have significant ranges of solution. The δ-Bi2O3 polymorph, stable from 730°C to 825°C is an end-member of a face-centered cubic solid solution (FCCss) that dissolves up to 2.7 % Ba. Ba-saturated FCCss and Bi-saturated rhombohedral (ß) solid solution (6.3 % Ba) melt at a eutectic at 753 °C. Less Bi is needed to saturate the ß phase at lower temperatures so α-Bi2O3 coexists with a ß phase containing 11.5 % Ba at 646°C.The amount of Ba required to saturate the ß phase depends less strongly on temperature. Ba-saturated ß phase contains 19 % Ba at 700°C. These ß materials are in equilibrium with an oxide near Bi3BaO5.5 that undergoes two polymorphic transformations: low-temperature cubic (<700°C); orthorhombic (700-730°C); high-temperature cubic (Cht). There is a eutectic between the ß and Cht, at 775±6°C. At T<700°C, 26.5 % Ba saturates the latter but it can take in up to 29.5 % Ba (at 812°C). At T<815°C the coexisting phase is BiBaO3. A tetragonal (T) phase forms by reaction of Ch, and BiBaO3 and has ~35% BaO at 815°C. The composition span of T widens as temperature increases. Cht, melts incongruently at 820°C to a liquid and T with 29.8 % Ba. Above that temperature the Bi-saturated and Ba-saturated T phases both become more Ba-rich as temperature is elevated. T melts incongruently to liquid and BiBaO3.The δ-Bi2O3 and ß, both anion conductors, have structures based on that of fluorite. The other oxides have perovskite-like structures. Half of the Bi in BiBaO3 is pentavalent and half is trivalent. The other oxides appear to have all their Bi in the 3+ state.
Synthesis of Na1-xLnxNbO3(Ln=La, Nd, Sm, Gd) and their Structures and Electrical Properties
Authors: Sugimoto Wataru , Naito Masahiro , Sugahara Yoshiyuki , Kuroda Kazuyuki 
Published: April 2011

AbstractPolycrystalline samples of Na1-xLnxNbO3(Ln=La, Nd, Sm, Gd) were synthesized by solid-state reactions. Reduced niobates were obtained as single-phase perovskites forx=0.05 and 0.1 when Ln=La and Nd andx=0.05 when Ln=Sm. The Gd-substituted samples could not be prepared under the synthetic conditions studied. Compositional analysis of the products revealed a slight amount of sodium loss during synthesis. The structural parameters obtained from Rietveld analysis revealed an increase in unit-cell volume. All of the obtained samples showed semiconducting behavior. Similar semiconducting behavior was observed for the same x value, suggesting the weak influence of the different Ln species to the electrical properties.
Melting Relations of Bi2O3-SrO-CaO-CuO Superconductors at Various Oxygen Fugacities
Authors: Styve Vance J. , Geny Joel , Meen James K. , Elthon Don 
Published: April 2011

AbstractIn an effort to synthesize monophasic superconducting oxides in the quaternary system Bi2O3-SrO-CaO-CuO two studies have been conducted. The melting relations of superconducting oxides Bi2Sr2CaCu2O8 (Bi-2212) and Bi2Sr2Ca2Cu3O10 (Bi-2223) have been experimentally investigated separately at various oxygen fugacities {f(O2)} from I to 3. 10-4 bar at 1 atm total pressure. Several interesting properties of the system have been found with respect to this portion of the quaternary; the modal proportions of liquid produced at the solidus depend on the oxygen fugacity. The amount of liquid produced at the Bi-2212 solidus reached a maximum of approximately 75% at f(O2) = 0.1 bar, Bi-2223's maximum proportion of liquid formed at the solidus continues to increase up to the lowest oxygen fugacity f(O2) = 0.01 bar studied. CaO (with a small amount of dissolved SrO) is the liquidus phase over the entire range of f(O2) for both compositions. (Sr,Ca)2CuO3 is the second phase to crystallize at high f(O2) but, as f(O2) decreases, its primary phase volume shifts for Bi-2212, and Bi2(Ca,Sr)3O6 is the second phase to form. (Sr,Ca)14Cu24O41 exhibited liquidus relationship only in high oxygen fugacities. Only Bi-2212 melts to assemblages that include bismuth-bearing crystalline phases. Bi9(Ca,Sr)16Ox is stable only at high oxygen fugacities and Bi2(Ca,Sr)3O6 is only stable at the lower values. At the lowest oxygen fugacities, Bi-2212 liquids crystallize (SrCa)CuO2 at a higher temperature than (SrCa)2CuO3 and no (Sr,Ca)CuO2 was found in Bi-2223 bulk compositions. These variations apply constraints on the positions of the univariant and invariant phase equilibria and these constraints are described.
207PB NMR and Monte Carlo Studies of Ionic Solid Solutions
Authors: Kye Young-Sik , Herreros Bruno , Harbison Gerard S. 
Published: April 2011

AbstractLead, strontium and barium nitrates, like the titanates of the same cations, form a continuous set of solid solutions. 207Pb NMR spectra of mixed crystals of lead/strontium nitrate and lead/barium nitrate each show up to 13 lines, arising from lead ions with from zero to twelve Pb2+ nearest-neighbor cations replaced by Sr2+ or Ba2+. In the case of (Pb,Sr)(NO3)2 these shifted lines are further split by the multiplicity of inequivalent nearest-neighbor replacements. The average shift per Sr2+ ion is 21.8 ppm; that for Ba2+ is smaller. Using Monte Carlo/Metropolis calculations, the intensities of the resonances can be fit to statistical models of Pb2+ and Sr2+ ion distributions, and used to probe the microenergetics of solid solution formation. The data can be satisfactorily fit by distributions in which the cations are slightly clustered, with like pairs of nearest neighbors being favored by 120 J/mol over unlike pairs. Interestingly, this finding is inconsistent with the conventional interpretation of powder diffraction results for the mixed crystals, where the dependence of lattice parameter on composition shows a slight positive curvature, generally held to indicate a favorable interaction between unlike ions.
Energetics of Nitridophosphates PON and “LiNaPON Glasses”
Authors: Tessier F. , Le Sauze A. , Marchand R. , Navrotsky A. 
Published: April 2011

AbstractStructural analogies have been demonstrated between the β-cristobalite, α-quartz and moganite phases of PON and its isoelectronic analog SiO2. Whereas the energetics of silica are well established, no data exist for the energetics of formation of nitridophosphates. High temperature solution calorimetry was used to determine the energetics of PON samples and a series of “LiNaPON oxynitride” glasses. Enthalpies of formation were measured as -371.71 ± 4.45 kJ/mol and -356.14 ± 3.98 for β-cristobalite and amorphous PON respectively and as -961.88 ± 3.86 kJ/mol for a 9 wt% nitrogen containing LiNaPON glass. These values constitute the first set of energetics data necessary to achieve further thermodynamic studies on nitridophosphates.
Novel Polar Intermetallic π-Systems along the Zintl Border
Authors: Guloy Arnold M. , Xu Zhihong 
Published: April 2011

AbstractStudies have shown that complex Zintl phases exhibit a rich diversity of crystal structures. These have also revealed a remarkable success of the Zintl concept in rationalizing stoichiometry, crystal structure and chemical bonding of many main group intermetallics. Still there are unresolved questions about the usefulness of the concept in explaining structure-property relationships in intermetallics near the Zintl border, and as a rational tool in designing new materials. Limitations of the concept are represented by violations often associated with “electron-deficient” phases that contain Group 13 metalloids. Recent investigations on “electron-deficient” Zintl phases containing post transition metals have led to the synthesis of a number of novel inorganic-intermetallic π-systems. Since unique structures and properties are already apparent in normal Zintl phases, it is anticipated that the exploratory synthesis and characterization of conjugated and multiple-bonded inorganic systems will produce not only unusual crystal chemistry but interesting physical properties as well. We report on new complex Zintl phases that include the semiconducting SrCa2In2Ge - which features [In2Ge]6- chains and represents a novel inorganic conjugated π-system analogous to a polyallyl chain with In-In double bonds, and Ca5In9Sn6 - which contains In trimers, [In3]5- analogous and isoelectronic with the aromatic cyclopropenium cation, [C3H3]+. These unusual materials, Zintl π-systems, represent a promising class of electronic materials with a range of potential applications.
Synthesis and Characterization of A New Weak Ferromagnet: Fe(II) Ethylene-BIS-(Phosphonates)
Authors: Bellitto C. , Federici F. , Mahmoud M.R. , Ibrahim S.A. 
Published: April 2011

AbstractIron(II)-ethylene-bis-(phosphonates), Fe2[O3P-(CH2)2-PO3]·2H2O was synthesized by reaction of [FeSO4]·7H2O and the corresponding ethylene-bis-(phosphonic acid) and it was characterized by X-ray powder diffraction, thermogravimetry, UV-visible and infrared spectroscopy, and the magnetic properties were studied by a SQUID magnetometer. The metal-ion is in the d6 high-spin electronic configuration and it appears to have an octahedral coordination. The thermal variation of the d.c. magnetic susceptibility of Fe2[O3P-(CH2)2-PO3]·2H2O follows the Curie-Weiss law, with a negative Weiss constant of θ =-55K. Below 100K, the susceptibility increases until a peak at TN=24K is observed, and this is associated to the three-dimensional antiferromagnetic order. Below 24K, Fe2[O3P-(CH2)2-PO3]·2H2O behaves as a “weak” ferromagnet and it represents an example of an unusual kind of molecular-based magnetic materials, having a finite zero-field magnetization.
Preparation of SiC-Diamond Nanocomposites
Authors: Gierlotka S. , Ekimov E. , Palosz B. , Stel'makh S. , Pielaszek R. , Witek A. , Grzanka E. , Presz A. , Boysen H. , Bismayer U. 
Published: April 2011

AbstractCompacts of composites SiC-diamond were made by infiltration of Si into nanocrystalline diamond powders in a toroid-type press under the pressure of 7.7 GPa at 1300 °C. In-situ high pressure diffraction studies of these processes were performed in MAX80 cubic anvil press at a pressure of 8.5 GPa in temperatures up to 1800°C in HASYLAB at DESY, Hamburg, Germany. Sintering was performed for (i) pure nanocrystalline diamond powders, (ii) a mixture of nanocrystalline powders of diamond and nanocrystalline SiC, (iii) a mixture of nanocrystalline diamond with microcrystalline Si powders and (iv) compacts of nanocrystalline diamond infiltrated by Si. The SiC-diamond composites obtained by infiltration of Si have best physical properties: hardness similar to conventional diamond compacts (approximately 50 GPa), highest density 3.35 g cm-3 and uniform nanocrystalline microstructure.
Gradually Varying Intermediate Valence of Fe in La1-xCaxFeO3
Authors: Li Jiangong 
Published: April 2011

AbstractThe isomer shift of La1-xCaxFeO3 decreases gradually from the value for trivalent iron to that for tetravalent iron, as the Ca content x increases from 0 to 1. This indicates that iron in La1-xCaxFeO3 has an intermediate valence state. The intermediate valence state of iron increases gradually from trivalence to tetravalence. This can be interpreted as being due to electron delocalization among iron ions on identical octahedral sites. The Mossbauer spectra at various temperatures of La0.5Ca0.5FeO3 and their theoretical treatment show that electron delocalization slows down with decreasing temperature.
The Structure Directing Role of Cations in the Synthesis of Low Silica LTL Zeolites
Authors: Burton A. , Lobo R. F. 
Published: April 2011

AbstractThe structure and extraframework cations of dehydrated zeolites (Ba,K)-G,L (Si/Al=1) and (Ba,Li)-G,L (Si/Al=1) are characterized by powder neutron diffraction. The results provide direct evidence of the similar structure directing roles which barium and potassium play in the syntheses of zeolites with the LTL topology.
A - and B - Site Order in (Na1/2La1/2)(Mg1/3Ta2/3)O3 Perovskites
Authors: Dupont L. , Chai L. , Davies P.K. 
Published: April 2011

AbstractThe “1:2” family of A2+(B2+1/3B+5+2/3)O3 (e.g. B2+ = Mg, Ni, Zn; B5+ = Nb, Ta) mixed metal perovskites typically adopt a 1:2 layered ordered structure when A = Ba and Sr, and a 1:1 ordered doubled perovskite structure for A = Pb. To understand the stability of the cation order in these systems and explore how the different cation correlations affect their dielectric and ferroelectric properties, the response of several members of this family of perovskites to a series of chemical substitutions and thermal treatments have been explored. In this paper we present results for a system where the divalent A cation is replaced by a 1:1 mixture of Na+ and La3+. At all temperatures this substitution stabilizes 1:1 B-site ordering. Below ~ 950°C an additional ordering reaction occurs on the A sub-lattice with Na and La occupying alternate layers along the c axis. The formation of different orientational variants of the A-site ordered phase produces a twinned nano-domain structure which in turn perturbs the length-scale, but not the symmetry, of the order on the B-site lattice. The presence of (Na1/2La1/2) on the A-site is apparently effective in destabilizing the 1:2 layering of the B-site cations observed in alkaline earth systems, possibly through unfavorable local charge imbalances.
Low-Temperature Multistep Topotactic Routes to New Mixed-Valence Perovskites
Authors: Lalena J.N. , McIntyre R.A. , Cushing B.L. , Thomas K.A. , Heintz J.L. , Seip C.T. , O'Connor C.J. , Wiley J.B. 
Published: April 2011

AbstractMultistep topotactic routes are exploited to introduce mixed-valency into mixed-metal oxides at low temperatures (≤ 350°C). A new set of single- and triple-layered perovskites, Na1-x-yCax/2LaTiO4and Na2-x+yCax/2La2Ti3O10, respectively, has been prepared by a combination of ion exchange and reductive intercalation. The single-layer series are metastable compounds. The magnetic and electronic behavior of the triple-layer titanate is consistent with Anderson localization effects, while those of the single-layer materials are more complex; samples demonstrate “Hurd-like” conductivity and an unusual magnetic response. The details of the synthesis and characterization of these materials are presented and their magnetic and electronic behavior discussed.
Ambient temperature synthesis of polycrystalline thin films of lithium cobalt oxide with controlled crystallites† orientations
Authors: Goldner R.B. , Zerigian P. , Liu T.Y. , Clay N. , Vereda F. , Haas T.E. 
Published: April 2011

ABSTRACTPolycrystalline thin films of lithium cobalt oxide (nominally LiCo02) have been deposited by a process which we have named, ion beam directed assembly (IBDA). It is similar to ion assisted deposition (IAD) or ion beam assisted deposition (IBAD), but the major difference is that in IBDA the ion beam directs, via the vector momenta of the ions, rather than merely assists, the growth. Hence, we also term the process directed assembly to distinguish it from self assembly. Also, in directed assembly the ions may or may not become an integral part of the film's composition.In this paper we wish to show that the IBDA process may be capable of controlling microstructure, e.g., in the case of polycrystalline films, control the orientations of the crystallites. For LiCoO2 we have observed this in two ways - by X-ray analysis, and electrochemically, by lithium diffusivity measurements. In particular, we have observed increased lithium diffusivities (≥ 10−8 cm 2/s) in IBDA deposited films as compared to that found for rf sputter deposited films (z 10−10 cm2/s). In addition, the coulometric titration characteristics of an IBDA deposited Lil−yCoO2 are very similar to those of sputtered deposited films (for lithium extraction/insertion, y ≤0.5, and for quasi-equilibrium voltages up to 4.2 volts).
Resonant Raman Characterization of Polyparaphenylene Based Carbon Materials
Authors: Marucci A. , Brown S. D. M. , Pimenta M. A. , Matthews M. J. , Dresselhaus M. S. , Endo M. 
Published: April 2011

ABSTRACTThe structure of the polymer polyparaphenylene (PPP), heat-treated at temperatures (THT) between 650°C≤ THT ≤750°C and prepared according to either the Kovacic or the Yamamoto methods, is studied by the resonant Raman technique using five laser excitation energies Elaer in the range 1.92–3.05 eV. The resonant Raman analysis allows identification of the benzenoid and quinoid forms of PPP as well as the amorphous material associated with the onset of the carbonization process. The results enable us to follow the evolution of the PPP polymer with heat-treatment temperature and to determine the differences between the materials prepared using the two different methods.
Electrical and Esr Studies of Lithium Manganese Oxide Spinels
Authors: Julien C. , Gendron F. , Ziolkiewicz S. , Nazri G.A. 
Published: April 2011

ABSTRACTWe report electrical properties of the lithium manganospinel LiMn2 O 4 and its delithiated/lithiated forms, Li1−x−∂Mn2−∂O4 with 0.0≤x≤0.4 and 0.00≤∂0.18. The electrical conductivity has been determined from d.c. measurements as a function of temperature and lithium content in the host lattice. LiMn2O4 exhibits a phase transition in the vicinity of 280 K, which disappears in the lithium-rich samples. Electrical data are analysed using the model of small-polaron transport. ESR spectroscopy has been applied to identify the singular structural features. Investigations as a function of temperature show a reliable determination of the modifications in the cationic sublattice and of the lithium overstoichiometry. The hopping conductivity mechanism between the Mn3+ and Mn4+ sites gives a coherent explanation for the observed ESR signal of cyclotron resonance.
Physical Properties of Lithium-Cobalt Oxides Grown by Laser Ablation
Authors: Escobar-Alarcon L. , Haro-Poniatowski E. , Jimenez-Jarquin J. , Massot M. , Julien C. 
Published: April 2011

ABSTRACTWe have studied the growth and the physical properties of LiCoO2 films as a function of formation conditions, i.e., substrate temperature and partial oxygen pressure. These films were grown on various substrates by the laser ablation technique using a Nd:YAG laser at 100 MW/cm2 power density. LiCoO2 films were characterized by XRD, SEM, and vibrational spectroscopy. The synthesized compounds show high homogeneity in composition and in particle dimension. The main advantage of this method is the less time needed for the reaction to occur completely. Raman scattering spectroscopy provides information on the local environment of cations.