Study of the composition dependence of the ionic conductivity of LiH_{x}D_{1-x} alloys

Hydride Conductivity in Nitride Hydrides

Nitride hydrides are a largely unexplored class of materials with promising applications in solid-state hydrogen fuel cells. Here, we use first-principles calculations to characterize defects and ionic mobility in Sr$_2$LiH$_2$N (SLHN), a nitride hydride with high hydride conductivity. Calculating defect formation energies, we find that SLHN contains high concentrations of hydrogen interstitials (H$_i$). H$_i^-$ migrates with very low energetic barriers, which, together with its low formation energy, implies that SLHN will have excellent hydride kinetics, potentially surpassing those of other …

Epitaxial Stabilisation of ${\bf \mathrm{Ge_{1-x}Sn_x}}$ Alloys

The thermodynamic stability of germanium tin $\mathrm{Ge_{1-x}Sn_x}$ alloys is investigated across the composition range $0 \le x \le 1$ by applying density functional theory (DFT) together with the cluster expansion formalism (CE). It is known that GeSn alloys are immiscible and that non-equilibrium growth techniques are required to produce metastable films and nanostructures. Insight into the driving forces behind component segregation is gained by investigating the equilibrium thermodynamics of GeSn systems. The alloy free energy of mixing is computed by combining enthalpies from CE with en…

TiCoSb Half-Heusler合金热导率的剧烈改变：通过晶格软化和离子极化进行声子工程

Drastic modification in thermal conductivity of TiCoSb Half-Heusler alloy: Phonon engineering by lattice softening and ionic polarization

本研究通过实验发现TiCoSb半哈斯勒合金中热导率随Sb掺杂发生约47%的剧烈变化，归因于晶格软化与离子极化引起的声子群速度改变和LO-TO分裂，TiCoSb1.02样品热导率最低。

Substrate-dependent Photoconductivity Dynamics in a High-efficiency Hybrid Perovskite Alloy

Films of (FA$_{0.79}$MA$_{0.16}$Cs$_{0.05}$)$_{0.97}$Pb(I$_{0.84}$Br$_{0.16}$)$_{2.97}$ were grown over TiO$_{2}$, SnO$_{2}$, ITO, and NiO. Film conductivity was interrogated by measuring the in-phase and out-of-phase forces acting between the film and a charged microcantilever. We followed the films' conductivity vs. time, frequency, light intensity, and temperature (233 to 312 K). Perovskite conductivity was high and light-independent over ITO and NiO. Over TiO$_{2}$ and SnO$_{2}$, the conductivity was low in the dark, increased with light intensity, and persisted for 10's of seconds after t…

Homogeneous limit of Cd(1-x)Mn(x)GeAs(2) alloy: electrical and magnetic properties

We present the studies of structural, electrical, and magnetic properties of bulk Cd$_{1\textrm{-}x}$Mn$_{x}$GeAs$_{2}$ crystals with low Mn content, $x$, varying from 0 to 0.037. The studied samples have excellent crystallographic quality indicated by the presence of diffraction patterns never before observed experimentally for this compound. The electrical transport in our samples is dominated by thermal activation of conducting holes from the impurity states to the valence band with activation energy of about 200$\;$meV. The defect states acting as ionic scattering centers with concentratio…

Electrically Enhanced Exchange Bias via Solid State Magneto-Ionics

Electrically induced ionic motion offers a new way to realize voltage-controlled magnetism, opening the door to a new generation of logic, sensor, and data storage technologies. Here, we demonstrate an effective approach to magneto-ionically and electrically tune exchange bias in Gd/Ni$_{1-x}$Co$_{x}$O thin films (x=0.50, 0.67), where neither of the layers alone is ferromagnetic at room temperature. The Gd capping layer deposited onto antiferromagnetic Ni$_{1-x}$Co$_{x}$O initiates a solid-state redox reaction that reduces an interfacial region of the oxide to ferromagnetic NiCo. Exchange bias…

用于三元合金系统预测玻璃形成能力的机器学习框架

A Machine Learning Framework for Predicting Glass-Forming Ability in Ternary Alloy Systems

本文提出基于随机森林和极端梯度提升的机器学习方法，用于预测三元氧化物玻璃的玻璃形成能力，揭示了电负性变异等关键特征对预测性能的影响。