Temperature and pressure dependence of the nonmetal-metal transition in sodium-ammonia solutions (electrical conductivity and pressure-volume-temperature data up to 150.deg. and 1000 bars

Hahne, S.; Schindewolf, U.

doi:10.1021/j100593a023

Cited by 8 publications

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“…During this time the NH 3 remained liquid (i.e., the temperature stayed below −33 °C). As expected, the conductivity increased with increasing temperature, which matches published results . After a further 2 h, the sample was exposed to air, resulting in a decline in the conductivity consistent with oxidation of the reduced [graphene] n − species.…”

Section: Results and Discussionsupporting

confidence: 89%

Overcoming Catalyst Residue Inhibition of the Functionalization of Single-Walled Carbon Nanotubes via the Billups–Birch Reduction

Zhang

Pham

Lawal

et al. 2017

ACS Appl. Mater. Interfaces

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The Billups-Birch Reduction chemistry has been shown to functionalize single-walled carbon nanotubes (SWCNTs) without damaging the sidewalls, but has challenges in scalability. Currently published work uses a large mole ratio of Li to carbon atoms in the SWCNT (Li:C) to account for lithium amide formation, however this increases the cost and hazard of the reaction. We report here the systematic understanding of the effect of various parameters on the extent of functionalization using resonant Raman spectroscopy. Addition of 1-iodododecane yielded alkyl-functionalized SWCNTs, which were isolated by solvent extraction and evaporation, and purified by a hydrocarbon wash. The presence of SWCNT growth catalyst residue (Fe) was shown to have a strong adverse effect on SWCNT functionalization. Chlorination-based SWCNT purification reduced the amount of residual Fe, and achieve a maximum I/I ratio using a Li:C ratio of 6:1 in a reaction time of 30 min. This result is consistent with published literature requiring 20-fold mole equivalents of Li per mole SWCNT with a reaction time of over 12 h. This new understanding of the factors influencing the functionalization chemistry will help cut down material and process costs, and also increase the selectivity of the reaction toward the desired product.

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Section: Results and Discussionsupporting

confidence: 89%

Overcoming Catalyst Residue Inhibition of the Functionalization of Single-Walled Carbon Nanotubes via the Billups–Birch Reduction

Zhang

Pham

Lawal

et al. 2017

ACS Appl. Mater. Interfaces

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Metal‐Nonmetal Transition in Metal‐Ammonia Solutions

Breitschwerdt¹,

Radscheit²

1976

Ber Bunsenges Phys Chem

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The properties of metal‐ammonia solutions in the concentration range of the metal‐nonmetal transition between 0.1 and 10 mol percent metal (MPM) are discussed. The high‐frequency electrical properties show a number of characteristic features in this intermediate concentration range, such as additional dielectric relaxations at about 0.1 MPM and 0.7 MPM for LiNH3 and NaNH3, respectively, and a resonance‐like behavior at about 1.0 MPM and 1.5 MPM for LiNH3 and NaNH3, respectively. For both LiNH3 and NaNH3 the real part of the high‐frequency dielectric function changes to large negative values around 2.5 MPM, indicating a transition to metallic behavior at high frequencies. The high‐frequency properties, which are also discussed in terms of electron conductivity, are explained quantitatively as a function of concentration, temperature, and frequency using a model of polaron hopping. The metal‐nonmetal transition is related to structural changes in the solutions which lead to phase separations in LiNH3 and NaNH3 at lower temperatures. The structural properties of the solutions are investigated using sound velocity and ultrasonic attenuation data. Concentration and temperature dependence of the ultrasonic attenuation in LiNH3 and NaNH3 can be described quantitatively in terms of structural fluctuation.

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Electrical Conductivity and Thermopower of Metal Ammonia Solutions

Hahne

Krebs

Schindewolf

1976

Ber Bunsenges Phys Chem

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Data of equivalent conductivity of sodium ammonia solutions in a wide concentration, temperature and pressure range prove that the nonmetal‐metal transition is favoured by increasing temperature and disfavoured by increasing pressure. Some data on the temperature dependence of the thermopower support the concept of activated transport (semiconduction) in the transition range, although the combination of thermopower and conductivity data does not follow the simple theory of semiconductors. In conclusion it is shown that the conductivity behaviour of metal ammonia solutions can be explained by a homogeneous chemical equilibrium between solvated electrons (electrolytic conduction) and free electrons (metallic conduction) which as usually depends on concentration, temperature and pressure.

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Temperature and pressure dependence of the nonmetal-metal transition in sodium-ammonia solutions (electrical conductivity and pressure-volume-temperature data up to 150.deg. and 1000 bars

Cited by 8 publications

References 0 publications

Overcoming Catalyst Residue Inhibition of the Functionalization of Single-Walled Carbon Nanotubes via the Billups–Birch Reduction

Overcoming Catalyst Residue Inhibition of the Functionalization of Single-Walled Carbon Nanotubes via the Billups–Birch Reduction

Metal‐Nonmetal Transition in Metal‐Ammonia Solutions

Electrical Conductivity and Thermopower of Metal Ammonia Solutions

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