{'fraction_non_alphanumeric': 0.02888446215139442, 'fraction_numerical': 0.008964143426294821, 'mean_word_length': 5.320754716981132, '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}}
Revisiting phase transitions in Ca-modified lead titanate ceramics using synchrotron XRD

Lead titanate (PbTiO3) is a prototype ferroelectric material. At high temperatures, it presents the ideal centrosymmetric cubic perovskite structure with Pm-3m symmetry. Cooling down to 770 K, a first-order phase transition from the paraelectric phase to the non-centrosymmetric tetragonal P4mm is observed [1]. Its high para-ferroelectric phase transition temperature would be promising for its technological application. However, the high anisotropy (6% c/a at room temperature) combined with its positive thermal expansion in cooling, makes it impossible to produce this ceramic in the form of bulk. Doping the Pb or Ti site of the perovskite are options to decrease the anisotropy only enough to makes possible bulk production [2]. In this work, we study the effect of isovalent substitution of Pb by Ca in paraelectric to ferroelectric phase transition by structural, dielectric, and ferroelectric properties.