Upon submitting their paper, they kept the hydrogen at a low temperature and at a high pressure until the acceptance of their work, in case the pair was instructed to perform other tests. In order to create the metallic hydrogen, Silvera and Días followed procedures necessary ensure not to break the deice’s compressing diamonds. Unfortunately, the sample was accidentally destroyed, a common fate in high-pressure physics, as both Professor Silvera and Dias explained (7). What is the current status of the experiment? For instance, magnetic levitation vehicles could become more accessible, electronics could become more efficient, and space travel could become cheaper and to farther distances. If both properties are confirmed to be true, we might see a revolution in electronics and transportation. Such a property has only been achieved at extremely low temperatures in other materials, while metallic hydrogen is theorized to behave this way at 17˚C, far higher than other candidates. Superconductivity means the material could carry currents without any resistance or energy loss. If such is the case, metallic hydrogen could potentially be an extremely efficient way of storing energy, for instance to be used as a rocket propellant. Metastability means the material would remain in the same metallic state even after the high pressure is released (just like diamond is a metastable form of carbon). Theoretical calculations predict metallic hydrogen to be a metastable material as well as a room-temperature superconductor (5,6). Once the scientists achieved the ultra-high pressure and observed a phase transition, they measured the reflectivity of the sample to be consistent with that of a metal, as well as obtained a density in agreement with theoretical predictions. Dias summarized the special technique as “adding a diffusion barrier to a very polished diamond with as little defects as possible” (4). The key therefore, lies in modifying the diamond to make it sustain the immense force necessary for this experiment’s success. Achieving such pressure had its challenges: “The diamonds we use to contain the samples tend to break or allow diffusion,” explained Dias “the hydrogen sample can diffuse into the diamond and cause defects, which will weaken the diamond and make it break before reaching the ultra-high pressure needed ” (4). Indeed this recent success was obtained with a pressure of 495 GPa, a pressure never achieved before in hydrogen experiments (3). While the necessary density of the metallic phase was predicted accurately in the 1930s, the predicted pressure to achieve a metallic phase at the time was around 25 GPa, while modern predictions placed the figures at 400-500 GPa (1,2). An essential component to Silvera and Dias’ success was achieving the correct pressure to obtain a transition to a metallic state. Generating a sample of metallic hydrogen has been an ongoing project for many years in several laboratories, and the Silvera lab has finally succeeded. Both Silvera and Dias agreed to be interviewed for this article. Originally theorised in 1935 by physicists Eugene Wigner and Hillard Bell Huntington, the ongoing project was finally brought to fruition at Harvard University in January 2017. The generation of metallic hydrogen by Professor Isaac Silvera and postdoctoral fellow Ranga Dias, PhD represents a crucial advance in the field of high-pressure physics.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |