{'fraction_non_alphanumeric': 0.06775700934579439, 'fraction_numerical': 0.052570093457943924, 'mean_word_length': 4.79054054054054, '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}}
EPR Study of Characteristics of Fe3+ Ions with Cubic Symmetry in CaF2 Crystals

CaF2 single crystals containing Fe3+ ions with cubic symmetry are prepared by co-doping alkali ions as charge compensators, and they are studied at room temperature with an x-band EPR spectrometer. The spectrum observed is described by a spin Hamiltonian, \mathscrH=gβH·S+(a/6)[Sx4+Sy4+Sz4-(1/5)S(S+1)(3S2+3S-1)], where S=5/2 and Sz is along [001] direction. The spin parameters are determined as g=2.005±0.0005 and |a|=(37.3±0.4)×10-4 cm-1. The EPR signals are stable at room temperature, but they decay appreciably rapidly at high temperatures above 550°C. The activation energies for the decay are determined as ranging from 1.1 to 2.9 eV, which are dependent upon the kinds of doped alkali ions and also upon the atmospheres around the crystals during the heat treatments.