High carbon Fe-C composites with starting concentrations of 10, 20, 30, and 40 wt% Fe (2.3 - 12.5 atomic % Fe) were prepared by ball milling followed by annealing. Increasing the Fe concentration and annealing temperature resulted in catalytic graphitization of the carbon. Mossbauer spectroscopy analysis indicated that Fe concentration and annealing temperature had significant effects on the Fe magnetic hyperfine field, quadrupole splitting, and the formation of gamma-Fe. When used as electrodes in Li cells, the electrochemistry of ball milled Fe-C powders annealed at low temperatures resembled that of amorphous carbon. Fe-C with 40 wt% Fe annealed at 2000 degrees C had electrochemical characteristics of a pristine graphite electrode with good cycling performance. These results demonstrate that lithium battery negative electrodes with good cycling performance can be produced from catalytically prepared graphite. (C) The Author(s) 2016. Published by ECS. All rights reserved.

Magnetostrictive rods of the approximate composition Fe82Ga18 have been produced with a preferred 〈100〉 axial crystallographic texture. Randomly oriented polycrystalline rods were cast by a suction extraction technique and a preferred 〈100〉 axial crystallographic texture was introduced through zone melting. Capacitance dilatometery showed that the as-cast rods and oriented zone-melted rods had saturation magnetostrictions of approximately 50ppm and 100ppm, respectively. Subsequent annealing of zone-melted rods resulted in a re-orientation of the axial crystallographic texture to a preferential 〈111〉 direction along with a corresponding reduction of the saturation magnetostriction.

Samples of Sn30TM30C40 and of Sn30Co15TM15C40, with TM=3d transition metals, were prepared by vertical-axis attritor milling. The structure and performance of these samples were studied by X-ray diffraction (XRD) and by electrochemical testing. The XRD patterns of Sn30TM30C40 show an amorphous-like diffraction pattern only for the sample with TM=Co. The other prepared samples show broadened Bragg peaks of their main starting material, along with an amorphous-like background, even after 32h of milling. Samples with TM=Co and TM=Ni show stable differential capacity versus potential plots and stable cycling for at least 100 cycles with reversible capacities of 425 and 250mAhg−1, respectively. All samples prepared with 15at.% Co show good capacity retention for at least 100 cycles ranging from 270mAhg−1 for samples with TM=Ni to 500mAhg−1 for samples with TM=Ti. The differential capacity versus potential plots for all the prepared Sn30Co15TM15C40 samples show similar structure to that of Sn30Co30C40 except when TM=Cu. This shows the possibility of preparing tin-based negative electrode materials using a combination of cobalt and TM, especially if one looks to reduce the cobalt content.

To examine the process of family communication about contraception and abortion from the perspective of mothers, fathers and teen boys and girls in African-American families.

Crystal growth of Ge1-xSix alloy with [Si] composition ranging from 1 to 30 at.%. using the travelling solvent method (TSM) is presented. Single crystal growth was obtained using a Ge seed crystal. The fluctuations in chemical composition along and transverse to the Ge1-xSix samples were typically less than ±0.4 and 0.3 at.%, respectively. The macroscopic composition inhomogeneities along the growth axis in the TSM grown samples correlate strongly with those within the Ge1-xSix feedrods which in turn depend markedly on the quenching rate of the molten alloy. Hall effect measurements indicate that there is a conductivity type reversal in the samples from n to p type with Si composition above 1 at.% in the alloy.

Single crystal growth of Ge1−xSix alloys with Si composition ranging from 2 to 15 at. %. using the traveling solvent method (TSM) is presented. The growths were carried out using Ge 〈111〉 seeds or a self-seeding method. Electron microprobe, Laue x-ray, and Hall effect techniques were used to characterize the quality of the materials. The standard deviations associated with the composition profiles along and transverse to the growth direction were less than 0.4 and 0.3 at. %, respectively. A change in conductivity from n to p type in the TSM samples was observed at a Si composition <5 at. %.

Rotating a water-cooled substrate rapidly under Mo and Sn sputter sources made sequentially sputtered molybdenum–tin thin films. The layer thickness deposited during each circuit under each source was selected between 2 and 20 Å and films of several micrometers overall thickness were prepared. The produced films were characterized using wide-angle and small-angle X-ray scattering, 119Sn Mössbauer spectroscopy, differential scanning calorimetry and transmission electron microscopy. Films of three major types are observed: (1) homogeneous crystalline body centered cubic Mo1−xSnx is produced when x is less than approximately 0.45 and when the layer thickness deposited in each pass under the targets is small; (2) nanocrystalline BCC Mo1−xSnx having x approximately equal to 0.45 coexisting with nanocrystalline tin when the overall tin content is greater than 45% atomic and the layer thickness deposited in each pass under the targets is small; and (3) lamina of composition modulated Mo1−xSnx disturbed by nanoscopic clusters of tin when the overall tin content is greater than approximately 40% atomic and the layer thickness of Mo deposited in each pass is greater than approximately 6 Å. This is the first report of BCC Mo1−xSnx for 0≤x≤0.45. A ‘phase diagram’ of the observed film types is presented.

The electrochemical alloying reaction of Li with isostructural A(2)B acid Al-based alloys has been investigated. The binary A(2)B alloys we selected (Sb2Ti, Sb2V, Sn2Co, Sn2Mn, Sn2Fe, Al2Cu, and Ge2Fe) are isostructural (Al2Cu type) and comprise an active element (A) that alloys with lithium, and an inactive one (B) that does not. These compounds were prepared by mechanical alloying and have small grain size (10-20 nm). With the exception of Al2Cu, we observed a full reaction of A with lithium (A(2)B + 2xLi --> B + 2Li(x)A, where the theoretical values of x are 1 for Al, 3 for Sb, and 4.4 fur Si, Ge, and Sn). Extremely slow electrochemical cycling at 55 degrees C and potentiostatic tests at lithium potential proved the total inactivity of the Al2Cu vs. lithium. However, thermodynamic considerations predict that the reaction of A12Cu with Li should occur and that the formation of LiAl should be observed. Other Ri-transition metal intermetallics were studied and were also found to be inert toward Li, suggesting that the,Al-transition metal bond has unique features. (C) 2000 The Electrochemical Society. S0013-4651(99)10-070-3. All rights reserved.

One polycrystalline and one single-crystal CdGeAs2 feed rods with 9mm diameter were processed by the float-zone technique under microgravity on SPACEHAB-SH04 during the STS-77 Space Shuttle Endeavour mission. An eutectic salt of LiCl and KCl was used as an encapsulant to suppress Cd and As evaporation from the melt. Post-flight chemical, structural, electronic, and optical characterization of the two samples is presented. Single-crystal growth was achieved using a seed crystal.

Two CdGeAs2 samples have been successfully grown under microgravity on SPACEHAB-SH04 during the STS-77 Space Shuttle Endeavour mission. One polycrystalline and one single crystal CdGeAs2 feed rods with 9mm diameter were processed by the float-zone method. An eutectic salt of LiCl and KCl was used as an encapsulant to suppress Cd and As evaporation from the melt. Numerical modeling of the float zone shows that salt encapsulation plays an important role in reducing Marangoni convection. The interface between the salt and CdGeAs2 was shown not to deform in the float zone due to the weak capillary pressure.

Blends of pitch and polysilane were investigated for the effects of their initial oxygen and sulfur contents on the composition and electrochemical performances of the resulting pyrolyzed Si-containing disordered carbons. We found that the irreversible capacity of these materials (around 170 mAh/g) is caused by the presence of oxygen and sulfur which act as trapping agents for Li during the first discharge. The irreversible capacity is not strongly correlated to the Si content although the reversible capacity is (max. 500 mAh/g). When there are significant amounts of S and O in the blends, appreciable amounts of Si can be incorporated in the char as Si-O-S-C glass. These Si atoms are electrochemically active, and thus result in high reversible capacity. On the other hand, as the O and S contents are reduced, the chars are found to contain less Si and unfortunately most of the Si is in electrochemically inactive Si-C instead of Si-O-S-C active glass. Thus, this results in a dramatic reduction of the irreversible capacity but also of the reversible capacity. Although disordered carbons containing pure silicon clusters were previously prepared by Chemical Vapor Deposition (CVD), this work shows that the pyrolysis of pitch/polysilane blends is less suited for the preparation of similar materials. (C) 1999 Elsevier Science B.V. All rights reserved.

A series of samples pyrolysed to different temperatures were synthesized from dewatered sucrose. These samples were characterised by wide-angle X-Ray scattering (WAXS), small-angle X-Ray scattering (SAXS), BET surface area and CO2 gas adsorption measurements. WAXS and SAXS measurements were used to determine the average number of graphene sheets stacked in a parallel fashion and the average micropore size (8–10 Å in radius), respectively. As the heat treatment temperature (HTT) was increased, WAXS and SAXS measurements show that the internal structure of these materials is changing in a fashion consistent with the falling card model. CO2 gas adsorption measurements show that the micropores in the sample are closing, forming an intermediate partially closed micropore, with increasing HTT (predominantly in the range 900–1400°C). A model of micropore closure is presented that describes the number of open micropores as a function of the heat treatment temperature and exposure time. A simple adsorption model based on the Langmuir equation is presented and was used to determine the number of open micropores in the sample.

"Non-graphitizable'' or "hard" carbon anode materials have almost twice the capacity (per unit mass) of graphitic materials that currently represent the industrial standard for Li-ion batteries. One problem with hard carbon is the small hysteresis in the voltage profile between charge and discharge. This small hysteresis has been correlated to residual hydrogen content after pyrolysis (<0.5% by mass) and can almost be eliminated by increasing the heat-treatment temperature (HTT) above 1100 degrees C. However at this temperature hard carbon begins to show a reduction in reversible capacity. This capacity reduction is correlated to a shift in chemical potential of lithium inserted into the hard-carbon structure and to the closure of micropores in the sample. Hard carbons were prepared by pyrolysis of sucrose between HTTs of 900 and 1400 degrees C. The structure of these materials was:determined by wide angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS). WAXS results show that the number of stacked layers increases with HTT, and SAXS measurements show that the micropore size also increases with HTT. N-2 Brunauer-Emmett-Teller (BET) surface area and CO2 gas adsorption measurements show a dramatic decrease in surface area and open micropore volume for HTTs greater than 1100 degrees C. These results indicate that the micropores in the samples begin to close and produce what we call "embedded fullerenes." Based on.recent results of intercalation in C-60, we believe that embedded fullerenes are impenetrable by lithium, and as a result the number of available sites for lithium insertion decreases. This, we propose, is the mechanism for the observed capacity loss in hard carbon at HTTs greater than 1100 degrees C.