재료 과학
대기압 고온 초전도체를 향한 작은 발걸음
초전도성 한계
Electricity has been one of the most transformative technologies in history, allowing for the transmission of a very useful form of energy over long distances. But every “normal” electric system faces electric resistance, which results in the generation of heat when an electric current is applied.
An alternative exists: the so-called superconductive materials. Superconductive materials have an electric resistance of zero, which allows for extremely powerful currents to be used without generating heat.
Without superconductivity, plenty of modern technology would not be possible, including particle accelerators (for example, the CERN), MRI, and 자기부상 열차.
Superconductivity will be a crucial component of the most promising megaprojects and technological innovation, like ITER and 핵융합, 대량 구동기, 양자 컴퓨터, etc.
Zero-loss electric power lines could also be crucial in developing ultra-long grid connections helping buffer the production of renewables over weather conditions and time zones, solving some of the limitations of solar and wind power.
The problem so far is that all these applications are based on low-temperature superconductivity, where the materials are superconductive only when cooled down to low temperatures like 20°K/-253°C/-423°F, usually requiring liquid helium.
This makes it not only too complex for any but the most demanding applications (maglev, MRI, etc.) but also very costly, making it uneconomical for many applications that could benefit from superconductive material or any large-scale use.
초전도성에 이르는 다양한 경로
Other forms of superconductivity than ultra-cold materials require constant very high pressure for the material to stay superconductive. This might be interesting from an experimental point of view, but even less practical for industrial applications or in energy and transportation infrastructures.
High-temperature superconductivity might become an option, notably with the puzzling case of LK-99 (a form of copper-substituted lead apatite – CSLA), a new type of ambient-pressure, room-temperature superconductor. The claim was immediately contested and criticized as a hoax or a measurement error, but 다른 연구자들은 실제로 무언가가 일어나고 있을지도 모른다고 발견했습니다.
Anyway, the case of LK-99 illustrates that we are far from knowing everything about what makes superconductivity possible.
Recently, WSe₂의 트위스티드 이중층 (tungsten selenium) appeared to be a good material candidate as well.
Researchers at the University of Houston, University at Buffalo, University of Illinois, National Sun Yet-Sen University (Taiwan), and Intellectual Venture are opening the realm of possible superconducting material further, removing the need for high pressure except during the manufacturing of the material.
They published their results1 in the Proceedings of the National Academy of Sciences (PNAS), under the title “Creation, stabilization, and investigation at ambient pressure of pressure-induced superconductivity in Bi0.5Sb1.5Te3”.
초전도성과 압력
The connection between high pressure and superconductivity has been studied for more than 30 years now, since their initial discovery in 1993. What happens is that the pressure modifies the atomic behavior of the material, which itself affects its electrical properties.
“2001년에 과학자들은 고압을 BST에 적용하면 페르미 표면 토폴로지가 변해 열전 성능이 향상된다고 의심했습니다.
압력, 토폴로지, 그리고 초전도성 사이의 이러한 연결이 우리의 관심을 끌었습니다.”
Pr. Liangzi Deng – University of Houston 연구원
Pr. Deng (left) and Pr. Chu (right) – 출처: University of Houston
The problem is that for a material to be useful for industrial applications, it usually needs to display interesting properties when in a metastable state, so it can hold these properties in “normal” conditions.
So far, the requirement of very high pressure has not only hindered the study of materials superconductive in these conditions, but also made very elusive any future practical applications, as it would not work to keep a cable, magnet, or railroad component under such extreme pressure conditions, even less than the ultra-cold conditions requirement for the superconductors currently used.
고압 퀜칭
Maintaining the superconductivity properties at normal pressure is what the researchers just achieved.
To do so, they used a special semiconductor material called BST (Bismuth-Antimony-Tellurium / Bi0.5Sb1.5Te3). Under pressures up to ~50 GPa (Gigapascal), or 500,000x stronger than atmospheric pressure (1 bar), BST displays three superconducting phases (BST-I, -II, and -III), with the first one appearing at 4 GPa.
The researchers developed a procedure called pressure-quench protocol (PQP), allowing for the pressure-induced phase to persist at room pressure.
Not only was the BST-I superconducting phase preserved, but also the BST-II and -III phases.
They used a diamond anvil to reach the extreme pressure required.
The electric and magnetic properties were analyzed using a very sensitive instrument called Magnetization Property Measurement System (MPMS)
작동 온도 개선
When tested, these superconducting phases were not only initially stable at room pressure, but also preserved these states over time and when exposed to higher temperatures.
This, however, does not mean this is a room-temperature superconductor, only that the phases are stable in normal pressure and able to display actual superconductivity when cooled down.
BST is known to display superconductivity at 10.2°K (-262.9°C / -441.3°F). The researchers found that the depressurization and the pressure-quench protocol both improved BST’s transition temperature, making it a good option for improving existing superconductive materials.
“This experiment clearly demonstrates that one may stabilize the high-pressure-induced phase at ambient pressure via a subtle electronic transition without a symmetry change, offering a novel avenue to retain the material phases of interest and values that ordinarily exist only under pressure.
Pr. Paul Chu – Researcher at the University of Houston
미래 응용
While not immediately creating superconductive material, this opens the way for a new method to discover and design superconductive materials.
Until now, high-pressure superconductivity had very few practical applications, and a room-temperature superconductor had to display this characteristic independent of the effect of pressure.
If the pressure-quench protocol can be generalized, this could help stabilize in normal conditions superconductive materials that are promising, but so far only worked at high pressure.
“Interestingly, this experiment revealed a novel approach to discovering new states of matter that do not exist at ambient pressure originally or even under high-pressure conditions.
It demonstrates that PQP is a powerful tool for exploring and creating uncharted regions of material phase diagrams.”
Pr. Liangzi Deng – Researcher at the University of Houston
It could also improve known superconductors so that their transition temperature is higher.
This could open the way for successive states, making it possible to create a superconductor that can work with “just” 78°K (-195°C / -319°F), or the boiling point of liquid nitrogen, a much easier-to-handle coolant than liquid helium, which is for example currently used in the superconducting magnets of ITER.
초전도성 기업
American Superconductor Corporation
(AMSC )
AMSC is a company providing energy solutions for the power grid, ships, and wind energy. In general, the more power-hungry or massive a system is, the more it requires superconducting technology to avoid overheating.
Despite its name, ASMC provides not only superconductor systems but also, for example, gear drivetrains for wind turbines.
The company is riding multiple growth drivers, from the trend of electrification, and digitalization (including AI datacenters), but also the reshoring of US manufacturing capacities and the need for Navies of the Anglosphere to modernize in response to growing geopolitical risks.
In the power supply segment, AMSC has seen a steady rise in orders. This was driven by semiconductor fabs looking to be protected from power grid fluctuations, helping the grid deal with the intermittent nature of renewables, and power supply & controls at industrial sites.
In the wind turbine segment, AMSC is mostly active with Electrical Control System (ECS). Historically, ESC was a strong segment for the company with the 2MW wind turbines, but it has progressively declined. AMSC aims for a rebound thanks to the new 3MW turbine design, with a special focus on the Indian market.
출처: American Superconductor Corporation
For military ships, ASMC provides the “AMSC’s High Temperature Superconductor Magnetic Mine Countermeasure “, a system to alter the magnetic signature of the ships to protect them from sea mines. This is sold to the US, Canadian, and UK navies, with $75M worth of orders so far.
Overall, ASMC is doing best with leveraging superconductor technology in niche applications viable today, while likely being ready to deploy further advances in the future. It should also be noted by investors that the stock has experienced extreme volatility in the past, and to calculate the risks accordingly.
연구 참고:
1.Deng, B. et al, (2025) 대기압에서 압력 유도 초전도성을 가진 Bi0.5Sb1.5Te3의 생성, 안정화 및 조사. Proc. Natl. Acad. Sci. U.S.A. 122 (6) e2423102122, https://doi.org/10.1073/pnas.2423102122
