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This work aims to provide a thorough analysis of the phase transition dynamics in lead-free Bi0.5Na0.5TiO3 by in situ Raman spectroscopy, which is conducted under varying temperature and electric field. All the transition points are proved by the Raman response of phonon vibration, including the depolarization temperature at ∼200 °C, potential transition at ∼280 °C, Curie temperature at ∼320 °C and tetragonal-cubic transition above ∼500 °C. The vibration of A-site ions primarily contributes to the depolarization behavior, which is also responsible for the strong polarity in Bi0.5Na0.5TiO3. The transitions at ∼280 °C and ∼320 °C are confirmed by the phonon vibrations of the Ti–O bonds and the TiO6 octahedra. Meanwhile, the distortion of the Ti–O bonds and TiO6 octahedra under an electric field results in weak polarity. The thermal hysteresis behavior is related to the dynamics of phonon thermal evolution, because of the delayed response of the vibration mode to thermal activation of Ti–O bonds and TiO6 octahedra. The results lay a foundation for understanding the mechanism of the phase transition and polarization in Bi0.5Na0.5TiO3, guiding the design of functional devices for electromechanical applications. [ABSTRACT FROM AUTHOR]

Background: Femoral neck system (FNS) is a new type of internal fixation system which has been widely used for treating femoral neck fractures (FNFs).Compared with other internal fixation methods, FNS is minimally invasive and stable, and often achieves satisfactory short-term efficacy.Early failure of FNS (EFFNS) is not uncommon, however, there are few literatures and reports on factors associated with EFFNS.This study aimed to survey the prevalence and risk factors of EFFNS., Methods: We retrospectively analysed 62 patients with FNFs and underwent FNS fixation between 2019 and 2021. Demographic data, clinical characteristics, radiographic features and treatment process were described. Multifactor logistic regression analysis was used to analyse the different influencing factors., Results: Out of the 62 FNFs patients, 10 patients (16.1%) developed EFFNS, including 6 cases of severe femoral neck shortening, 2 cases of screw-out, 1 case of avascular necrosis of the femoral head and 1 case of nonunion. In the failure group, all patients were younger than 65 years old, which was significantly higher than 59.6% in the healing group (P = 0.012). There were no significant differences in sex(P = 0.490), BMI (P = 0.709), injured side (P = 0.312), injury mechanism (P = 0.617), reduction method(P = 0.570),femoral neck-shaft angle(P = 0.545), Pauwels classification (P = 0.564) and Garden classification (P = 0.195). Moreover, we not found that Garden classification (P = 0.464) and age (P = 0.128) were statistically significant risk factors for EFFNS at multivariate analysis., Conclusion: In this study, sex, BMI, injury side, injury mechanism, reduction method, Pauwels angle, femoral neck-shift angle, Pauwels classification and Garden classification were excluded as EFFNS risk factors. Moreover, our study demonstrated that age and Garden classification were not significant risk factors at multivariate analysis., Trial Registration: ChiCTR, ChiCTR2100051360. Registered on 21 September, 2021. https://www.chictr.org.cn/index.aspx ., (© 2023. The Author(s).)