Publications

New Li3Y(PS4)2 and Li5PS4Cl2 Superionic Conductors

Zhuoying’s first author paper on “Li3Y(PS4)2 and Li5PS4Cl2, New Lithium Superionic Conductors Predicted from Silver Thiophosphates using Efficiently Tiered Ab Initio Molecular Dynamics Simulations” has just been published in Chemistry of Materials (Special Issue on High-Throughput Functional Materials Discovery). In this work, we propose two new lithium superionic conductors, Li3Y(PS4)2 and Li5PS4Cl2, that are predicted to have excellent ionic conductivity and potentially better stability at the interfaces compared to current state-of-the-art superionic conductors. We welcome experimental researchers to attempt synthesis of these compounds and validation of our predictions!

Announcements

2016 year-end message by Prof Ong

2016 is coming to a close. Before some of you leave for the holidays, I would like to wish you all a Merry Christmas. This year, I have decided to start a new tradition – the year-end message.

It has been a great year for the Materials Virtual Lab. We have come a long way since our founding a little over three years ago, and I believe we have now firmly established ourselves as one of the up-and-coming computational materials research groups in the world. We will end 2016 on a high note with a little over 20 publications in highly respected journals. Funding is at a very healthy level for a group of our age, and we are now a dynamic family of three postdoctoral associates, ten graduate students and three undergraduates. Two of our earliest members (Zhi and Paul) have completed their Senate Exams, and another two (Chen, Zhenbin and Zhuoying) have completed their Literature Review Exams. We welcomed three new group members (Chi, Hui and Zhuonan), and one new-old group member (Richard) in Fall 2016. We will also soon say goodbye to Bala, who has found an excellent opportunity in NASA. We wish him all the best in his future endeavors.

Much of our success is due to you – the talented, hard-working computational-materials-informaticists, who make the discoveries that transform our understanding of materials and hopefully, improve the world we live in.

But we cannot rest on our laurels. We face three major challenges in the horizon. First, federal funding for climate research is likely to be constrained in the coming years. Nevertheless, I believe it is our moral imperative that we continue to work on materials research that help address this existential threat to the human race. We will of course seek to diversify both our research portfolio, as well as our funding sources. Second, standard computational methods are rapidly becoming “commoditized”. To stay relevant, we need to continually upgrade our ideas, methodological capabilities and unique research infrastructure. Finally, attracting diverse talent remains one of my top priorities. In light of the current environment, I want to reaffirm our group’s commitment to meritocratic, anti-discriminatory principles.

What does this mean for you? It means that I will expect more, not less, from you in 2017.

I will expect to see that you grow, not just scientifically, but also professionally and personally.

I will expect creative analyses and insights that blow my mind, and I will expect to see them presented in papers and presentations that are written in flowing prose of surpassing clarity.

I will expect each and everyone of you contribute to our unique software infrastructure with well-documented, robustly-tested code.

Above all, I will expect to see you contribute more ideas during meetings, and to each other’s projects.

I believe you have the potential to achieve all these things. Let us make 2017 an even better year for us than 2016.

Have a great holiday, and I will see some of you in the new year.

Shyue Ping

Announcements

We are hiring!

We are seeking to fill one postdoctoral position.

Successful candidates will have the opportunity to lead exciting projects that integrate advanced first principles methods, information technology and experiments (through external collaborations) to develop novel materials in energy storage and solid-state lighting. They will also receive mentoring to prepare them for future careers in academia or industry, including project management skills, proposal writing and effective scientific communication. More information can be found at http://www.materialsvirtuallab.org/positions.

The ideal candidate should demonstrate creativity, passion for scientific inquiry, and an ability to link fundamental science to real-world applications. The ideal candidate will also have:

  1. An advanced degree in materials science and/or solid-state physics.
  2. Experience with first principles methods, such as density functional theory (DFT), ab initio molecular dynamics, density functional perturbation theory or GW.
  3. Programming skills, preferably with experience in sustainable software development for robust widely used code bases.

Interested applicants should send the following materials to ongsp@ucsd.edu.

  1. A cover letter of no more than one page summarizing their research accomplishments and interests
  2. Curriculum vitae
  3. (Optional, but recommended) Samples of scientific codes they have written, either as a web link to a publicly accessible software repository or an email attachment.
Publications

Structure-Property-Composition Relations in β-SiAlON:Eu2+ Phosphor

Our work on “Elucidating Structure–Composition–Property Relationships of the β-SiAlON:Eu2+ Phosphor” has been published in Chemistry of Materials.

Using first-principles calculations, we identified and confirmed various chemical rules for Si−Al, O−N, and Eu activator ordering in β-SiAlON, one of the most promising narrow-band green phosphors for high-power light-emitting diodes and liquid crystal display backlighting with wide color gamut. Through the construction of energetically favorable models based on these chemical rules, we studied the effect of oxygen content and Eu2+ activator concentrations on the local EuN9 activator environment, and its impact on important photoluminescence properties such as emission peak position (using the band gap as a proxy), bandwidth, and thermal quenching resistance.  Based on these insights, we discuss potential strategies for further composition optimization of β-SiAlON.

News

Ocean Discovery Institute

Professor Ong gave a talk on careers in STEM to 5th grade students from Hamilton Elementary at the Ocean Discovery Institute last Fri (Oct 14, 2016). He also worked with on building remotely operated vehicles. Check out the pictures below!

field-trip_10-14-16_hamilton_geyer_rovs1 ong-1

Publications

Room-Temperature All-solid-state Na-ion Batteries with Cl-doped Na3PS4

In collaboration with the Laboratory of Energy Storage and Conversion (LESC), we have developed a room-temperature all-solid-state rechargeable sodium-ion battery utilizing a novel Cl-doped Na3PS4 superionic conductor. The Cl-doped tetragonal Na3PS4 solid electrolyte exhibits room-temperature Na+ conductivity exceeding 1 mS/cm, and an all-solid-state TiS2/t-Na3−xPS4−xClx/Na cell utilizing this solid electrolyte can be cycled at room-temperature at a rate of C/10 with a capacity of about 80 mAh/g over 10 cycles. We show that this excellent electrochemical performance is not only due to the high Na+ conductivity of the solid electrolyte, but also due to the effect that “salting” Na3PS4 has on the formation of an electronically insulating, ionically conducting solid electrolyte interphase.

This work is published in Scientific Reports. The co-first authors are Iek-Heng Chu (MAVRL), Christopher S. Kompella (LESC) and Han Nguyen (LESC), and the corresponding authors are Professors Shirley Meng and Shyue Ping Ong.

Publications

Data-driven Methods for the Study and Design of Alkali Superionic Conductors

Our article on “Data-driven First Principles Methods for the Study and Design of Alkali Superionic Conductors” has been published in  Chemistry of Materials as part of an invited Methods and Protocols special topic. In this work, we provide a detailed exposition of the first principles techniques that can be used to design alkali superionic conductors, a topic of high current interest. Accompanying this article is a repository of well-documented Jupyter notebooks that allows any researcher to easily reproduce the analysis and apply the same techniques to other materials.

The article is available online and the notebooks are available at the following Github repo.