Two-dimensional ordering in 1-propanol-graphite-oxide intercalates: isotopic effects

Intercalation of fully deuterated 1-propyl alcohol into graphite oxide is studied by means of the unique capabilities offered by the NIMROD neutron diffractometer. We develop methods to estimate the amount of intercalant present within the neutron irradiated volume using for the purpose of the set of constraints implicit in the outputs of the Gudrun diffraction data treatment software. The results are compared to those from our previous study on of fully hydrogenated 1-propanol intercalation [C. Cabrillo, F. Barroso-Bujans, R. Fernandez-Perea, F. Fernandez-Alonso, D. Bowron and F.J. Bermejo, Carbon 100, 546 (2016)] where a two-dimensional ordering transition under slow heating from 100 K was discovered. The rearrangement of the 1-propanol molecular pillars did allow for the formation of bilayer intercalation. In contrast, sample deuteration leads to remarkable differences in both the intercalation kinetics and intercalate thermal response, avoiding the two-dimensional transition which would lead to bilayer formation. Finally, neutron diffraction results have enabled us to disentangle the highly anomalous behaviour exhibited by hitherto unpublished broad band dielectric spectroscopy studies which are now understood on the basis of the two-dimensional transition just referred to.This work was supported in part by the Spanish Agencia Estatal de Investigación (AEI) and the Fondo Europeo de Desarrollo Regional (FEDER, UE) under Grant No. MAT2016-75354-P and in part by Grant No. MAT2012-33633 from the Spanish Dirección General de Investigación Científica y Técnica. The authors also gratefully acknowledge the support of Basque Government (IT-1175-19), and the UK Science & Technology Facilities Council for partial financial support and access to beamtime at the ISIS Facility