"Happiness is all struggling." Turning the blueprint into reality, carrying out the reforms to the end, all calling for the spirit of struggle that is not in the air and not in the virtual voice, no need to step by step and do a good job. Heavenly rewards, and it changes with each passing day.
- General Secretary Xi’s 2018 New Year message
Looking back on 2017, the "Guiyan" satellite traveled into space, the C919 large passenger plane flew into the sky, the quantum computer was successfully developed, the sea rice was measured, the first domestic aircraft carrier was launched, and the "Haiyi" deep sea glider completed the deep sea observation, the first sea flammable ice test Successfully, the Yangshan Phase IV Automated Terminal officially opened, and the main project of the Hong Kong-Zhuhai-Macao Bridge was completed. The revival of Mercedes-Benz was on the vast land of the motherland... It was the hard work of all walks of life that made our country in various fields. Have achieved brilliant achievements. In this issue, we will focus on a major discovery of China's materials science in 2017 – the “three-state†phase change under the electric field control discovered by the research team of Tsinghua University.
In 2017, Nature published a research paper "Electric-field control of tri-state phase transformation with a selective dual-ion switch" from Chinese scientists. In the same period, it was published as "Condensed-matter physics: Functional materials at The news review of the flick of a switch gives high praise to the research results of Chinese scientists. For the first time, this study realized the phase transition of tri-state structure based on double-ion electric field control in a single material, and revealed the principle and application prospect of the regulation of optical, electrical and magnetic properties during the three-state phase transition.
Figure 1 a, b is a schematic diagram of electric field regulation, and c is a reversible phase transition between SrCoO3, SrCoO2.5 and HSrCoO2.5 by selective regulation of O2-ion and H+ ions.
Electric field regulation is the most commonly used regulation method in physics and materials science, but traditional electric field regulation can only regulate the valence state of an ion or enable the material to switch between two states. After careful design and design, the team led by Prof. Yu Pu realized the selective regulation of O2- and H+ ions in oxide SrCoO2.5 through ionic liquid electric field control, so that the materials are in SrCoO2.5 and SrCoO3-δ. And the reversible structural phase transition between the three phases of HSrCoO2.5 is the first realization of selective dual ion regulation and an important advancement of electric field regulation.
Figure 2 Electric field action, selective dual ion regulation three-phase magnetoelectric coupling
Since the three states of the material have different optical absorption properties in the visible and infrared regions, the study demonstrates the three-state electrochromic effect in the visible and infrared bands, while confirming that the tri-state phase transition is a non-volatile "The phase change of the characteristic, that is, after the voltage is removed, the structure and performance after the phase change will be maintained for a long time, thereby greatly reducing the energy consumption required to maintain the phase change.
If this result is applied to the glass, the brightness and temperature of the room can be adjusted by adjusting the light transmittance, thereby achieving the purpose of high efficiency and energy saving. The novel optical properties make this material invaluable in terms of energy saving and environmental protection. In addition, the three states of the material also have different electromagnetic properties, corresponding to antiferromagnetic insulators, ferromagnetic metals and weak ferromagnetic insulators, respectively. The tunable electromagnetic properties make this material equally promising for new spintronic device applications.
Figure 3 a. Three-state electrochromic effect, the different phases have different pass rates in the visible light band; b. Different phases have different pass rates in the infrared band, which can be applied to glass to adjust the indoor temperature.
It should be pointed out that traditional research usually realizes the design of novel phase and novel physical properties by means of external pressure or chemical doping in the process of material growth. However, in this study, the insertion and precipitation of ions are realized by electric field control and their corresponding The transformation of the physical phase provides a new kind of means for the regulation of material properties. The discovery can be widely extended to a range of other material systems, and it is expected to produce a large number of novel structural phase transitions and rich functional properties.
Here, we once again congratulate Professor Yu Pu on his gratifying scientific research results. I am also very honored that Quantum Design's equipment can help teachers in the experiment. Thanks to Professor Yu Pu for continuing to choose PPMS and complete the 10th PPMS comprehensive physical measurement of Tsinghua University. A small milestone in the system. As General Secretary Xi said, I hope that we can work side by side with all the scientific research workers. In the new year, we can maintain the firm belief of “opening the mountain and encountering water and bridging the bridgeâ€, which will add to the brilliant achievements of China's scientific research in 2018!
Article content: Partly from the official website of Tsinghua University
References: Electric-field control of tri-state phase transformation with a selective dual-ion switch (Nature, 2017, DOI: 10.1038/nature22389)
About Quantum Design
Quantum Design is the world's leading manufacturer and distributor of scientific equipment, and was founded in 1982 in San Diego, California. The company's SQUID Magnetic Measurement System (MPMS) and Material Integrated Physical Property Measurement System (PPMS) have become the world's recognized top-level measurement platform, widely distributed in the world's most research-oriented fields of materials, physics, chemistry, nanotechnology, etc. laboratory. In 2007, Quantum Design acquired LOT, the largest instrument distributor in Europe, and has become a world-renowned multinational company in the field of scientific instruments. At present, the company has dozens of branches and offices in the United Kingdom, the United States, France, Germany, Brazil, India, Japan and China, and operates in more than 100 countries and regions around the world. China is the most active market for Quantum Design, with offices or offices in Beijing, Shanghai and Guangzhou. Over the past decades, the company's cooperation with China's research and education fields has been fruitful, providing advanced equipment and high-quality services for the advancement of Chinese scientific research.
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