News

Our first PhD, Zhenbin Wang

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Congratulations to Zhenbin Wang for successfully defending his PhD thesis on Mar 6! Zhenbin is the first PhD graduate from the Materials Virtual Lab. Zhenbin joined the Materials Virtual Lab in Sep 2014 from the University of Science and Technology of China. During his PhD, Zhenbin has done ground-breaking work on the design and discovery of phosphor materials for white light-emitting diodes. He has devised new ways to screen for narrow-band red-emitting phosphors, provided useful optimization insights for the β-SiAlON green phosphor, and discovered a completely novel, earth-abundant phosphor host Sr2LiAlO4 that has been confirmed experimentally. Zhenbin is also an outstanding mentor to his fellow group members, having helped guide many to their own research findings. Check out Zhenbin’s tribute video from group members and photos of the defense and celebration by clicking on the full post!

Publications

Predicting Crystal Volumes

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Iek-Heng Chu’s paper on “Predicting the Volumes of Crystals” has been published in Computational Materials Science. In this collaborative work with the Hacking Materials group, we developed two schemes for predicting crystal volumes. Accurate crystal volume estimates are immensely useful for further experimental analysis, or to generate initial guesses for electronic structure optimizations. The volume prediction algorithms are implemented in the open-source pymatgen software.

Publications

First-order Interfacial Transformations in GB

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Hui Zheng is a co-author on a recently published article in Physical Review Letters on “First-Order Interfacial Transformations with a Critical Point: Breaking the Symmetry at a Symmetric Tilt Grain Boundary”. A collaboration with the Luo group, this work examines symmetry breaking in the ∑5 (210) GB using a modified genetic algorithm with Monte Carlo and molecular dynamics simulations. Read more about this work here.

Announcements

Sr2LiAlO4 – A novel earth-abundant phosphor with excellent color quality

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Our paper on “Mining Unexplored Chemistries for Phosphors for High-Color-Quality White-Light-Emitting Diodes” has been published in Joule. Using supercomputers and data mining, we identified Sr2LiAlO4, the first known Sr-Li-Al-O quaternary crystal, as a highly promising phosphor material in low-cost, high-color-quality white LEDs. Eu2+ and Ce3+-activated Sr2LiAlO4 phosphors exhibit broad green-yellow and blue emissions, respectively, with excellent thermal quenching resistance of > 88% intensity at 150oC. A prototype phosphor-converted white LED utilizing Sr2LiAlO4-based phosphors yields an excellent color rendering index exceeding 90. This work is a collaboration between the Materials Virtual Lab (UCSD), McKittrick group (UCSD) and Im group (Chonnam University). The lead authors are Zhenbin Wang, Jungmin Ha and Yoon Hwa Kim. More information about this work can be found in the Jacobs School of Engineering News as well as Science Daily, Phys.org, etc.

Announcements

Pythia

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Meet the newest member of our group, Pythia@Mavrl. Named after the famed oracle of antiquity, Pythia is a GPU-based deep learning machine from Lambda Labs. Our lab will be utilizing Pythia to develop cutting edge models for materials property prediction and discovery.

Announcements

Scialog: Advanced Energy Storage Team Award

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Prof Ong’s team is one of six teams selected for the Scialog Advanced Energy Storage Team Awards by the Research Corporation (Rescorp) for Science Advancement. This project is a collaboration with Prof Scott Warren of University of North Carolina at Chapel Hill and Prof Zhenxing Feng of Oregon State University to develop high-voltage dual-ion batteries. More information can be found in the Rescorp press release.

Publications

Zr strengthening of MoSi2

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Hui Zheng’s first paper on “Role of Zr in strengthening MoSi2 from density functional theory calculations” has just been published in Acta Materialia. MoSi2 is an important intermetallic with excellent oxidation resistance at high temperatures. However, “pesting” by oxygen limits its application at intermediate temperatures. Using DFT calculations, we show that Zr nanoparticles act as a getter for oxygen, and in the process, significantly strengthens MoSi2 interfaces and grain boundaries. We also use the Materials Project to efficiently screen for other potential getter elements using simple thermodynamic descriptors, a general approach that can be extended to other alloy systems of interest.

Publications

Probing Interfacial Reactions in All-solid-state Na-ion Batteries

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Hanmei’s first paper on “Probing Solid-Solid Interfacial Reactions in All-Solid-State Sodium-ion Batteries with First Principles Calculations” has just been published in Chemistry of Materials. In this comprehensive work, we show how explicit AIMD models can lead to different predictions of interfacial reaction products from simple thermodynamic approximations. Specifically, SO4 formation is predicted to be favored over PO4 formation at the interface between NaCoO2 and Na3PS4. We also identified several promising new candidates for buffer materials that potentially show lower reactivity with common electrodes and solid electrolytes.