Dr John Proctor's Outputs (32)

High pressure Raman, optical absorption, and resistivity study of SrCrO4 (2018)
Journal Article
Hakeem, M., Jackson, D., Hamlin, J., Errandonea, D., Proctor, J., & Bettinelli, M. (2018). High pressure Raman, optical absorption, and resistivity study of SrCrO4. Inorganic Chemistry, 57(13), 7550-7557. https://doi.org/10.1021/acs.inorgchem.8b00268

We studied the electronic and vibrational properties of monazite-type SrCrO4 under compression. The study extended the pressure range of previous studies from 26 to 58 GPa. The existence of two previously reported phase transitions was confirmed at 9... Read More about High pressure Raman, optical absorption, and resistivity study of SrCrO4.

Liquid mysteries (2018)
Journal Article
Proctor, J. (2018). Liquid mysteries. Physics world, 31(5), https://doi.org/10.1088/2058-7058/31/5/37

It's easy to assume there's nothing new to learn about liquids. John Proctor explains just how weird liquids can be at high pressures and why this work could shed light on planetary interiors.

Dynamics, thermodynamics and structure of liquids and supercritical fluids : crossover at the Frenkel line (2018)
Journal Article
Fomin, Y., Ryzhov, V., Tsiok, E., Proctor, J., Prescher, C., Prakapenka, V., …Brazhkin, V. (2018). Dynamics, thermodynamics and structure of liquids and supercritical fluids : crossover at the Frenkel line. Journal of Physics: Condensed Matter, 30(13), #134003. https://doi.org/10.1088/1361-648X/aaaf39

We review recent work aimed at understanding dynamical and thermodynamic properties of liquids and supercritical fluids. The focus of our discussion is on solid-like transverse collective modes, whose evolution in the supercritical fluids enables one... Read More about Dynamics, thermodynamics and structure of liquids and supercritical fluids : crossover at the Frenkel line.

Crossover between liquid-like and gas-like behaviour in CH4 at 400 K (2017)
Journal Article
Smith, D., Hakeem, M., Parisiades, P., Maynard-Casely, H., Foster, D., Eden, D., …Proctor, J. (2017). Crossover between liquid-like and gas-like behaviour in CH4 at 400 K. Physical Review E, 96(5), 052113. https://doi.org/10.1103/PhysRevE.96.052113

We report experimental evidence for a crossover between a liquid-like state and a gas-like state in fluid methane (CH4). This crossover is observed in all of our experiments, up to 397 K temperature; 2.1 times the critical temperature of methane. The... Read More about Crossover between liquid-like and gas-like behaviour in CH4 at 400 K.

Determining molecular orientation via single molecule SERS in a plasmonic nano-gap (2017)
Journal Article
Marshall, A., Stokes, J., Viscomi, F., Proctor, J., Gierschner, J., Bouillard, J., & Adawi, A. (2017). Determining molecular orientation via single molecule SERS in a plasmonic nano-gap. Nanoscale, 9(44), 17415-17421. https://doi.org/10.1039/c7nr05107g

In this work, plasmonic nano-gaps consisting of a silver nanoparticle coupled to an extended silver film have been fully optimized for single molecule Surface-Enhanced Raman Scattering (SERS) spectroscopy. The SERS signal was found to be strongly de... Read More about Determining molecular orientation via single molecule SERS in a plasmonic nano-gap.

Raman spectroscopy of methane (CH4 ) to 165 GPa : effect of structural changes on Raman spectra (2017)
Journal Article
Proctor, J., Maynard-Casely, H., Hakeem, M., & Cantiah, D. (2017). Raman spectroscopy of methane (CH4 ) to 165 GPa : effect of structural changes on Raman spectra. Journal of Raman Spectroscopy, 48(12), 1777-1782. https://doi.org/10.1002/jrs.5237

We have conducted a Raman study of methane (CH4), a major constituent of the outer planets, at pressures up to 165 GPa. We observe splitting of the principal Raman-active vibrational mode above 45 GPa and a nonlinear dependence of Raman peak position... Read More about Raman spectroscopy of methane (CH4 ) to 165 GPa : effect of structural changes on Raman spectra.

On the high-pressure phase stability and elastic properties of β-titanium alloys (2017)
Journal Article
and elastic properties of β-titanium alloys. Journal of Physics: Condensed Matter, 29(15), 155401-155401. https://doi.org/10.1088/1361-648X/aa60b6

We have studied the compressibility and stability of different β-titanium alloys at high pressure, including binary Ti–Mo, Ti–24Nb–4Zr–8Sn (Ti2448) and Ti–36Nb–2Ta–0.3O (gum metal). We observed stability of the β phase in these alloys to 40GPa, well... Read More about On the high-pressure phase stability and elastic properties of β-titanium alloys.

Monazite-type SrCrO4 under compression (2016)
Journal Article
Gleissner, J., Errandonea, D., Segura, A., Pellicer-Porres, J., Hakeem, M., Proctor, J., …Bettinelli, M. (2016). Monazite-type SrCrO4 under compression. Physical Review B, 94(134108), 1-13. https://doi.org/10.1103/PhysRevB.94.134108

We report a high-pressure study of monoclinic monazite-type SrCrO4 up to 26 GPa. Therein we combined x-ray diffraction, Raman, and optical-absorption measurements with ab initio calculations, to find a pressure-induced structural phase transition of... Read More about Monazite-type SrCrO4 under compression.

Hydrogenation of graphene by reaction at high pressure and high temperature (2015)
Journal Article
Smith, D., Howie, R., Crowe, I., Simionescu, C., Muryn, C., Vishnyakov, V., …Proctor, J. (2015). Hydrogenation of graphene by reaction at high pressure and high temperature. ACS nano, 9(8), 8279-8283. https://doi.org/10.1021/acsnano.5b02712

The chemical reaction between hydrogen and purely sp2-bonded graphene to form graphene's purely sp3-bonded analogue, graphane, potentially allows the synthesis of a much wider variety of novel two-dimensional materials by opening a pathway to the app... Read More about Hydrogenation of graphene by reaction at high pressure and high temperature.

Theoretical and experimental study of the crystal structures, lattice vibrations, and band structures of monazite-type PbCrO4, PbSeO4, SrCrO4, and SrSeO4 (2015)
Journal Article
Errandonea, D., Munoz, A., Rodiquez-Hernandez, P., Proctor, J., Sapina, F., & Bettinelli, M. (2015). Theoretical and experimental study of the crystal structures, lattice vibrations, and band structures of monazite-type PbCrO4, PbSeO4, SrCrO4, and SrSeO4. Inorganic Chemistry, 54, 7524-7524. https://doi.org/10.1021/acs.inorgchem.5b01135

The crystal structures, lattice vibrations, and electronic band structures of PbCrO4, PbSeO4, SrCrO4, and
SrSeO4 were studied by ab initio calculations, Raman spectroscopy, X-ray diffraction, and optical-absorption measurements. Calculations properl... Read More about Theoretical and experimental study of the crystal structures, lattice vibrations, and band structures of monazite-type PbCrO4, PbSeO4, SrCrO4, and SrSeO4.

Stabilization of boron carbide via silicon doping (2014)
Journal Article
Proctor, J., Bhakhri, V., Hao, R., Prior, T., Scheler, T., Gregoryanz, E., …Giuliani, F. (2015). Stabilization of boron carbide via silicon doping. Journal of Physics: Condensed Matter, 27(1), 015401. https://doi.org/10.1088/0953-8984/27/1/015401

Boron carbide is one of the lightest and hardest ceramics, but its applications are limited by its poor stability against a partial phase separation into separate boron and carbon. Phase separation is observed under high non-hydrostatic stress (both... Read More about Stabilization of boron carbide via silicon doping.

Equation of state and high-pressure/high-temperature phase diagram of magnesium (2014)
Journal Article
Stinton, G., Macleod, S., Cynn, H., Errandonea, D., Evans, W., Proctor, J., …McMahon, M. (2014). Equation of state and high-pressure/high-temperature phase diagram of magnesium. Physical review B: Condensed matter and materials physics, 90(13), 134105-134105. https://doi.org/10.1103/PhysRevB.90.134105

The phase diagram of magnesium has been investigated to 211 GPa at 300 K, and to 105 GPa at 4500 K, by using a combination of x-ray diffraction and resistive and laser heating. The ambient pressure hcp structure is found to start transforming to the... Read More about Equation of state and high-pressure/high-temperature phase diagram of magnesium.