{'fraction_non_alphanumeric': 0.03062583222370173, 'fraction_numerical': 0.03195739014647137, 'mean_word_length': 4.921259842519685, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Investigation of the phase diagram of selenium by means of Raman spectroscopy

We report a detailed and systematic Raman scattering investigation of the high pressure - high temperature (350–620 K, 0–20 GPa) phase diagram of elemental selenium starting from its trigonal structure (Se-I). Phase transitions to the tetragonal Se-VII phase were identified by the measured Raman pattern along several isotherms, upon pressurization and depressurization. A wide hysteresis region (∼10–15 GPa ) has been observed at 350 K, gradually reducing to about 3 GPa at 620 K. These results extend previous scattered determinations of the phase diagram and shifts the Se-I Se-VII transition line up to about 3 GPa at lower pressures and ∼150 K at lower temperatures.