Phase-field simulations of the effect of temperature and interface for zirconiumδ-hydrides

Hydride precipitation in zirconium cladding materials can damage their integrity and durability.Service temperature and material defects have a significant effect on the dynamic growth of hydrides.In this study,we have developed a phasefield model based on the assumption of elastic behaviour within a specific temperature range(613 K-653 K).This model allows us to study the influence of temperature and interfacial effects on the morphology,stress,and average growth rate of zirconium hydride.The results suggest that changes in temperature and interfacial energy influence the length-to-thickness ratio and average growth rate of the hydride morphology.The ultimate determinant of hydride orientation is the loss of interfacial coherency,primarily induced by interfacial dislocation defects and quantifiable by the mismatch degree q.An escalation in interfacial coherency loss leads to a transition of hydride growth from horizontal to vertical,accompanied by the onset of redirection behaviour.Interestingly,redirection occurs at a critical mismatch level,denoted as qc,and remains unaffected by variations in temperature and interfacial energy.However,this redirection leads to an increase in the maximum stress,which may influence the direction of hydride crack propagation.This research highlights the importance of interfacial coherency and provides valuable insights into the morphology and growth kinetics of hydrides in zirconium alloys.

针对电子极化子迁移的哈伯德U修正受限密度泛函理论方法:TiO_(2)实例研究

极化子的形成和迁移对过渡金属氧化物的物理和化学性质有重要影响.含哈伯德U修正的密度泛函理论和受限密度泛函理论方法经常被应用于小极化子迁移性质的理论研究.本文在投影缀加波框架中实现了哈伯德U修正的受限密度泛函理论(cDFT+U),并将其应用于体相TiO_(2)中的极化子迁移性质的计算.确认了哈伯德U的取值对极化子性质的理论预测有重要影响.采用基于cDFT计算所获得的哈伯德U值,可对TiO_(2)金红石和锐钛矿相中的极化子性质获得与实验符合很好的描述.本文表明,使用与理论上一致的方式计算获得的哈伯德U值,cDFT+U有望成为一种有效的不需经验输入而计算过渡金属氧化物极化子性质的第一性原理方法.

Effect of f–c hybridization on theγ→αphase transition of cerium studied by lanthanum doping

The hybridization between the localized 4f level(f) with conduction(c) electrons in γ-Ce upon cooling has been previously revealed in single crystalline thin films experimentally and theoretically, whereas its influence on the γ → α phase transition was not explicitly verified, due to the fact that the phase transition happened in the bulk-layer, leaving the surface in the γ phase. Here in our work, we circumvent this issue by investigating the effect of alloying addition of La on Ce, by means of crystal structure, electronic transport and angle resolved photoemission spectroscopy measurements, together with a phenomenological periodic Anderson model and a modified Anderson impurity model. Our current researches indicate that the weakening of f–c hybridization is the major factor in the suppression of γ → α phase transition by La doping. The consistency of our results with the effects of other rare earth and actinide alloying additions on the γ → α phase transition of Ce is also discussed. Our work demonstrates the importance of the interaction between f and c electrons in understanding the unconventional phase transition in Ce, which is intuitive for further researches on other rare earth and actinide metals and alloys with similar phase transition behaviors.

Participant attack on the deterministic measurement-device-independent quantum secret sharing protocol

In a recent article[Gao et al.,Sci.China-Phys.Mech.Astron.63,120311(2020)],a two-receiver measurement-deviceindependent quantum secret sharing(MDI-QSS)protocol was presented.It was proven to be secure against eavesdropping and generalized to the multireceiver case.However,the participant attack is a fatal threat to QSS protocols.Here,we highlight that a dishonest participant can obtain a sender’s secret message alone without introducing any detectable error,evidencing the vulnerability of the MDI-QSS protocol to the participant attack.