1. ABOUT THE DATASET -------------------- Title: Dataset for "The thermodynamic potential of ferroelectric nematic liquid crystals and consequences for polarisation switching" Creators: Diana Nikolova [1], Rachel Tuffin [2], Helen F. Gleeson [1], Mikhail Osipov [3] Organisations: 1. School of Physics and Astronomy, University of Leeds, LS2 9JT. 2. Merck Electronics KGaA, Frankfurter Str. 250, 64293 Darmstadt, Germany. 3. Department of Mathematics and Statistics, Univerity of Strathclyde, G1 1XH. Rights-holder(s): Copyright 2025 University of Leeds Publication Year: 2025 Description: The dataset contains spontaneous polarisation data for the ferroelectric nematic liquid crystal, FNLC-919. The tests are done using the current reversal technique (as described by Miyasato et al. in 1983) which gives values of polarisation when a voltage is applied to a sample, so the data mainly consists of polarisation values for the samples taken at a range of voltages. Tests were done to check the polarisation response in four different thicknesses (4, 10, 23, and 46 microns) as well as to check the longevity of a sample when preparation conditions were varied (i.e. if it was prepared in the polar (ferroelectric nematic) phase or one of the nonpolar phases (nematic or isotropic)). The relevant polarisation values are in the "Simpson Pol." column in the data files. The naming convention for files is described in the CONTENTS section of this README file. The methods for obtaining data are described in more detail in the related paper. Cite as: Nikolova, D. et al. (2025) Dataset for "The thermodynamic potential of ferroelectric nematic liquid crystals and consequences for polarisation switching". University of Leeds. [Dataset] https://doi.org/10.5518/1641. Related publication: Nikolova, D. et al. (2025) The thermodynamic potential of ferroelectric nematic liquid crystals and consequences for polarisation switching. (In preparation) Contact: py18dn@leeds.ac.uk 2. TERMS OF USE --------------- Copyright 2025 University of Leeds. This dataset is licensed under a Creative Commons Attribution 4.0 International Licence: https://creativecommons.org/licenses/by/4.0/. 3. PROJECT AND FUNDING INFORMATION ---------------------------------- Title: New applications in novel liquid crystal systems Dates: 01 Oct 2022 - 30 Sept 2026 Funding organisation: EPSRC and Merck Performance Materials Ltd. Grant no.: EP/V054724/1 4. CONTENTS ----------- File listing The data files have the following naming convention: the liquid crystal phase in which the sample was prepared, the cell thickness, and whether the sample cell electrodes were connected or disconnected during preparation, followed by a dash and the day of testing (where Day 0 is the day a sample was prepared). Here is a key for the notation: ISO = Isotropic phase, N = nematic phase, NF = ferroelectric nematic phase 4 = 4 micron, 10 = 10 micron, 23 = 23 micron, 46 = 46 micron C = connected electrodes, D = disconnected electrodes So for example, the file "ISO4C - Day 1.spon" contains the Day 1 test for the 4 micron sample prepared in the isotropic phase with connected electrodes. The only exception to this convention is the sample HT50, which is a 50 micron sample with homeotropic alignment (HT). The other samples have no alignment layer. The file format is ".spon", which can be opened as any text file with Microsoft Excel or other analysis software. The files contain seven columns: C (temperature), V (voltage), Hz (frequency), Lorenz Pol., Gauss Pol., Simpson Pol., and filename. These are not always necessarily in this order. Simpson Pol. is the column containing the polarisation values for the related publication. Lorenz and Gauss Pol. are alternative methods for integrating the current response to obtain polarisation values, and are disregarded in the reported data as Simpson Pol. was considered most accurate. It is important to note the Voltage is off by a factor of 10, as the data files do not account for the 10x amplifier in the system - therefore in order to replicate the data, one must multiply the Voltage column by 10. The "filename" column lists the raw current trace files which are integrated to obtain the polarisation values. The spontaneous polarisation is in units of nanoCoulombs per cm^2. For clarity, in the associated paper, it is presented in microColoumbs per cm^2 instead. There is one '.csv' file which contains polarisation data measured in electroporation cuvettes of gap thickness 1mm and 4mm. 5. METHODS ---------- Methods are described in the related paper, "The thermodynamic potential of ferroelectric nematic liquid crystals and consequences for polarisation switching".