TY - JOUR
T1 - Investigations into the nature of spontelectrics: nitrous oxide diluted in xenon
AU - Cassidy, Andrew
AU - Plekan, Oksana
AU - Dunger, Jack
AU - Balog, Richard
AU - Jones, Nykola
AU - Lasne, Jerome
AU - Rosu-Finsen, Alexander
AU - McCoustra, Martin R S
AU - Field, David
N1 - OA paid for using RSC Gold for Gold voucher scheme
PY - 2014/10/15
Y1 - 2014/10/15
N2 - The recent discovery of a new class of solids displaying bulk spontaneous electric fields as high as 108 V/m, so-called ‘spontelectrics’, poses fundamental and unresolved problems in solid state physics. The purpose of the present work is to delve more deeply into the nature of the interactions which give rise to the spontelectric effect in films of nitrous oxide (N2O), by observing the variation of the spontaneous field as the N2O molecules are physically removed from one another by dilution in Xe. Data, obtained using the ASTRID storage ring, are presented for films diluted by factors ξ = Xe/N2O of 0.9 to 67, at deposition temperatures of 38K, 44K and 48K, where films are laid down by deposition from a gas mixture. Results show that the spontelectric field decreases as ξ increases and that at ξ = 67 for 44K deposition, the spontelectric effect is absent. Reflection-absorption Infrared spectroscopy (RAIRS) data are also reported, providing insight into the structure of Xe/N2O films and specifically showing that N2O remains dispersed in the Xe/N2O films prepared here. A simplified theoretical model is developed which illustrates that electric fields can be understood in terms of dilution-dependent dipole orientation. This model is used to reproduce experimental data up to an average molecular separation, s, of ≥ 1.25 nm apart, ~4 times that associated with pure solid N2O. The disappearance of the spontelectric effect at larger average distances of separation, between s = 1.25 nm and s = 1.75 nm, is a phenomenon which cannot be described by any existing model but which shows that dipole-dipole interactions are an essential ingredient for the creation of the spontelectric state.
AB - The recent discovery of a new class of solids displaying bulk spontaneous electric fields as high as 108 V/m, so-called ‘spontelectrics’, poses fundamental and unresolved problems in solid state physics. The purpose of the present work is to delve more deeply into the nature of the interactions which give rise to the spontelectric effect in films of nitrous oxide (N2O), by observing the variation of the spontaneous field as the N2O molecules are physically removed from one another by dilution in Xe. Data, obtained using the ASTRID storage ring, are presented for films diluted by factors ξ = Xe/N2O of 0.9 to 67, at deposition temperatures of 38K, 44K and 48K, where films are laid down by deposition from a gas mixture. Results show that the spontelectric field decreases as ξ increases and that at ξ = 67 for 44K deposition, the spontelectric effect is absent. Reflection-absorption Infrared spectroscopy (RAIRS) data are also reported, providing insight into the structure of Xe/N2O films and specifically showing that N2O remains dispersed in the Xe/N2O films prepared here. A simplified theoretical model is developed which illustrates that electric fields can be understood in terms of dilution-dependent dipole orientation. This model is used to reproduce experimental data up to an average molecular separation, s, of ≥ 1.25 nm apart, ~4 times that associated with pure solid N2O. The disappearance of the spontelectric effect at larger average distances of separation, between s = 1.25 nm and s = 1.75 nm, is a phenomenon which cannot be described by any existing model but which shows that dipole-dipole interactions are an essential ingredient for the creation of the spontelectric state.
U2 - 10.1039/C4CP03659J
DO - 10.1039/C4CP03659J
M3 - Article
SN - 1463-9076
VL - 16
SP - 23843
EP - 23853
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 43
ER -