Fig. 3: Structure and dynamics in the liquid.
From: Structural dynamics of melting and glass formation in a two-dimensional hybrid perovskite
a Average Pb coordination number (navy circle, left axis) and average Pb-Br bond length (sky blue triangles, right axis) as a function of temperature, obtained from in situ variable-temperature X-ray total scattering measurements upon heating crystalline (S-NEA)2PbBr4. Solid lines connect the data points to guide the eye. b Temperature dependence of the Pb-Br stretching vibrational mode, measured by in situ THz/Far-IR spectroscopy during heating to 200 °C (navy circles) and subsequent cooling (sky blue triangles). Linear fits (XR) indicate different phases: crystalline (navy line), liquid (teal line) and supercooled liquid (sky blue line). In situ variable-temperature NMR experiments during heating of (S-NEA)2PbBr4 crystal (navy circles) and glass (sky blue triangles): c plot of 1H spin-lattice relaxation time (T1) versus 1000/T, showing distinct linear regions assigned to the crystalline (navy), liquid (teal) and supercooled liquid (sky blue) phases; (d, e) 207Pb chemical shift (δiso) as a function of temperature during heating of crystalline (d) and glassy (e) (S-NEA)2PbBr4, with solid lines representing linear fits for each phase. In (a) and (d, e), error bars represent fitting uncertainty in peak position determination. In (a–d), Tm denotes the melting temperature of crystalline (S-NEA)2PbBr4 (176°C), as indicated by the black dashed line. Source data are provided as a Source Data file.
