Thermally Induced Wurtzite to h‐BN Structural Transition

Abstract

Wurtzite (WZ) and hexagonal boron nitride (h‐BN) are closely related crystal structures, both of which belong to the hexagonal crystal family. However, the WZ structure is commonly found in binary compounds such as ZnO and CdS, whereas crystals having a h‐BN structure are very rare. In this study, a WZ→h‐BN structural transition is predicted to take place at high temperatures using molecular dynamic simulations with a generic pair potential model. This transition is entropically driven, whereby cations in crystal show extremely high mobility and are able to jump between nearby lattice sites when the temperature is higher than the critical point. Density function theory calculations for 14 AB compounds show that ZnO is the best candidate material that will undergo the WZ→h‐BN transition at high temperatures. This study predicts a new ferroelectric–paraelectric phase transition in WZ crystals that will change the materials’ physical properties such as piezoelectricity and pyroelectricity.

Bridging Biological and Artificial Neural Networks with Emerging Neuromorphic Devices: Fundamentals, Progress, and Challenges

“…For filamentary RRAM and CBRAM synapses, the control of conducting filament size (or its number) is likely the main approach to obtain analog conductance modulation. [158] The amplitude, duration, and numbers of electrical pulses all contribute to the change of filament size and the conductance of the device. Besides, there are also nonfilamentary RRAM devices that exhibit synaptic behaviors.…”

Strongly temperature dependent ferroelectric switching in AlN, Al1-xScxN, and Al1-xBxN thin films

“…Regardless of mechanism, the temperature dependence of E c is large, similar to that observed in HfO 2 -based ferroelectrics. 24 While the ferroelectric-to-paraelectric phase transition in substituted AlN is not known, molecular dynamics simulations suggest that if one exists, it is likely well above 1000 C. 25 Thus, at room temperature, films are far from T C .…”

Critical Evaluation of Five Classical Force Fields for CsPbI3: Limitations in Modeling Phase Stability and Transformations

“…Despite the fact that LJ-Coul has the simplest functional form and fewest parameters among five classical force fields considered in this work, it shows the best performance that can correctly predict all phase stability, solid–solid transitions, and melting of CsPbI 3 . This result is not surprising in the sense that the functional form of LJ-Coul is able to capture the ionic feature of CsPbI 3 crystals and other partially ionic crystals ,− and the parametrization process of this force field targeted accurate description of the CsPbI 3 polymorph stability. However, the simplicity of its functional forms and the fewer force field parameters also imply limitations in accuracy and transferability compared to those of more complex models.…”