@article{Haberl2022,

title = {Multi-Extreme Conditions at the Second Target Station},

author = {B. Haberl and D. G. Quirinale and C. Li and G. E. Granroth and H. Nojiri and M.-E. Donnelly and S. V. Ushakov and R. Boehler and B. L. Winn},

url = {https://aip.scitation.org/doi/10.1063/5.0093065},

doi = {10.1063/5.0093065},

year  = {2022},

date = {2022-08-22},

journal = { Review of Scientific Instruments},

volume = {93},

number = {083907},

issue = {8},

abstract = {Three concepts for the application of multi-extreme conditions under in situ neutron scattering are described here. The first concept is a neutron diamond anvil cell made from a non-magnetic alloy. It is shrunk in size to fit existing magnets and future magnet designs and is designed for best pressure stability upon cooling. This will allow for maximum pressures above 10 GPa to be applied simultaneously with (steady-state) high magnetic field and (ultra-)low temperature. Additionally, an implementation of miniature coils for neutron diamond cells is presented for pulsed-field applications. The second concept presents a set-up for laser-heating a neutron diamond cell using a defocused CO2 laser. Cell, anvil, and gasket stability will be achieved through stroboscopic measurements and maximum temperatures of 1500 K are anticipated at pressures to the megabar. The third concept presents a hybrid levitator to enable measurements of solids and liquids at temperatures in excess of 4000 K. This will be accomplished by a combination of bulk induction and surface laser heating and hyperbaric conditions to reduce evaporation rates. The potential for deployment of these multi-extreme environments within this first instrument suite of the Second Target Station is described with a special focus on VERDI, PIONEER, CENTAUR, and CHESS. Furthermore, considerations for deployment on future instruments, such as the one proposed as TITAN, are discussed. Overall, the development of these multi-extremes at the Second Target Station, but also beyond, will be highly advantageous for future experimentation and will give access to parameter space previously not possible for neutron scattering.},

keywords = {extreme environment, high pressure, instrument, neutron scattering},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Distinct Acoustic and Optical Phonon Dependences on Particle Size, Oxidation, and Temperature in Silicon Nanocrystals},

author = {Shuonan Chen and Devin Colema and Douglas L. Abernathy and Arnab Banerjee and Lorenzo Mangolini and Chen Li},

url = {https://pubs.acs.org/doi/abs/10.1021/acs.jpcc.2c04246},

doi = {10.1021/acs.jpcc.2c04246},

year  = {2022},

date = {2022-07-20},

journal = {Joural of Physical Chemistry C},

volume = {126},

issue = {30},

pages = {12704-12711},

abstract = {Phonon, as a momentum carrier, may play an important role in the photoluminescence of silicon nanocrystals. However, a systematic experimental study on phonon dynamics in spatially confined silicon systems remains limited. We used inelastic neutron scattering to investigate particle size, oxidation, and temperature effects on phonon dynamics of silicon nanocrystals by measuring phonon density of states of 12 and 50 nm silicon nanocrystals with several oxidation levels at different temperatures. We showed that the lattice vibrations of large silicon nanocrystals and bulk silicon are substantially different. We found that transverse acoustic phonon modes have much stronger dependences on particle size, oxidation, and temperature than optical phonon modes. We showed that the changes in phonon dynamics have the largest effect on vibrational entropy and free energy of silicon nanocrystals at intermediate temperatures. Our results shed light on phonon dynamics of silicon-based functional nanomaterials and will facilitate further investigations of electron\textendashphonon interactions in spatially confined silicon systems.},

keywords = {confinement, nanoparticle, neutron scattering, phonon, photonics, silicon},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Frustration-induced diffusive scattering anomaly and dimension change in FeGe2},

author = {Yaokun Su and Hillary L. Smith and Matthew B. Stone and Douglas L. Abernathy and Mark D. Lumsden and Carl P. Adams and Chen Li},

url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.024406},

doi = {10.1103/PhysRevB.106.024406},

year  = {2022},

date = {2022-07-11},

urldate = {2022-07-11},

journal = {Physical Review B},

volume = {106},

number = {024406},

abstract = {Magnetic frustration, arising from the competition of exchange interactions, has received great attention because of its relevance to exotic quantum phenomena in materials. In the current work, we report an unusual checkerboard-shaped scattering anomaly in FeGe2, far from the known incommensurate magnetic satellite peaks, by inelastic neutron scattering. More surprisingly, such phenomenon appears as spin dynamics at low temperature, but it becomes prominent above N\'{e}el transition as elastic scattering. A model Hamiltonian that includes an intraplane next-nearest neighbor was proposed and such anomaly is attributed to the near-perfect magnetic frustration and the emergence of unexpected two-dimensional magnetic order in the quasi-one-dimensional FeGe2.},

keywords = {frustration, magnetism, magnon-phonon, neutron, neutron scattering, phonon},

pubstate = {published},

tppubtype = {article}

}

@article{Hong2021,

title = {Phonon anharmonicity: a pertinent review of recent progress and perspective},

author = {B. Wei and Q. Sun and C. Li and J. Hong},

url = {https://link.springer.com/article/10.1007/s11433-021-1748-7},

doi = {10.1007/s11433-021-1748-7},

year  = {2021},

date = {2021-09-28},

urldate = {2021-07-01},

journal = {SCIENCE CHINA Physics, Mechanics \& Astronomy},

volume = {64},

number = {117001},

keywords = {anharmonicity, lifetime, metal-insulator transition, neutron scattering, thermal transport, vibrational entropy},

pubstate = {published},

tppubtype = {article}

}

@article{He2019,

title = {Anomalous neutron scattering ‘halo’ observed in highly oriented pyrolytic graphite},

author = {L. He and Chen W. Li and W.A. Hamilton and T. Hong and X. Tong and B.L. Winn and L. Crow and K. Bailey and N.C. Gallego},

url = {https://onlinelibrary.wiley.com/iucr/doi/10.1107/S1600576719001110},

doi = {10.1107/S1600576719001110},

year  = {2019},

date = {2019-03-05},

journal = {Journal of Applied Cyrstallography},

volume = {52},

number = {2},

pages = {296-303},

abstract = {Highly oriented pyrolytic graphite (HOPG) has been used as monochromators, analyzers and filters at neutron and X-ray scattering facilities for more than half a century. Interesting questions remain. In this work, the first observation of anomalous neutron ‘halo’ scattering of HOPG is reported. The scattering projects a ring onto the detector with a half-cone angle of 12.4􏰁, which surprisingly persists to incident neutron wavelengths far beyond the Bragg cutoff for graphite (6.71 A ̊ ). At longer wavelengths the ring is clearly a doublet with a splitting roughly proportional to wavelength. Sample tilting leads to the shift of the ring, which is wavelength dependent with longer wavelengths providing a smaller difference between the ring shift and the sample tilting. The ring broadens and weakens with decreasing HOPG quality. The lattice dynamics of graphite play a role in causing the scattering ring, as shown by the fact that the ring vanishes once the sample is cooled to 30 K. A possible interpretation by multiple scattering including elastic and inelastic processes is proposed.},

keywords = {graphite, neutron scattering, phonon},

pubstate = {published},

tppubtype = {article}

}

@article{Li2018,

title = {Probing the electrolyte infiltration behaviour of activated carbon supercapacitor electrodes by in situ neutron scattering using aqueous NaCl as electrolyte},

author = {Yiqun Li and Chen W. Li and Cong Li and Yan Chen and Ke An and Kai Landskron},

url = {https://www.sciencedirect.com/science/article/pii/S0008622318304330?via%3Dihub},

doi = {10.1016/j.carbon.2018.04.072},

year  = {2018},

date = {2018-04-24},

journal = {Carbon},

volume = {136},

pages = {139},

abstract = {In situcontrast-matched neutron scattering was used to probe the electrolyte infiltration behavior ofactivated supercapacitor carbon electrodes using an aquoeus 1 M NaCl solution. It was found that onlyabout 20% of the pore volume was infiltrated at chemical equilibrium. The partial infiltration can beattributed to the co-existence of hydrophilic and hydrophilic pores. The study suggests that for theachievement of optimal capacitance, supercapacitor electrodes should be evacuated before electrolyteinfiltration.},

keywords = {carbon, electrolyte, neutron scattering, super capacitor},

pubstate = {published},

tppubtype = {article}

}

@article{Haberl2017b,

title = {Wide-angle diamond cell for neutron scattering},

author = {Bianca Haberl and Sachith Dissanayake and Feng Ye and Luke L. Daemen and Yongqiang Cheng and Chen W. Li and A.-J. Ramirez-Cuesta and Masaaki Matsuda and Jamie J. Molaison and Reinhard Boehler},

url = {https://www.tandfonline.com/doi/full/10.1080/08957959.2017.1390571},

doi = {10.1080/08957959.2017.1390571},

year  = {2017},

date = {2017-10-19},

journal = {High Pressure Research},

volume = {37},

number = {4},

pages = {495-506},

abstract = {A new diamond cell with extreme apertures is described. It is tailored for a large variety of neutron scattering techniques such as inelastic neutron scattering and single-crystal diffraction both at the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor at the Oak Ridge National Laboratory. Simple springs enable forces of over 10 metric tons to be clamped in for low-temperature measurements. At present, low-cost polycrystalline diamond (Versimax) pressure anvils are used. We predict a routine pressure regime up to 20 GPa with sample volumes of ∼0.5 mm3. Future use of large CVD single-crystal diamond anvils will significantly expand this pressure range. We show examples for measurements at the SNAP, VISION and CORELLI beamlines of the SNS.},

keywords = {diamond anvil cell, diffraction, high pressure, neutron scattering},

pubstate = {published},

tppubtype = {article}

}