||Welcome to physicsdiscussionforum
You are currently viewing our boards as a guest, which gives you limited access to view most discussions and access our other features. By joining our free community, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content, and access many other special features. In addition, registered members also see less advertisements. Registration is fast, simple, and absolutely free, so please, join our community today!
Warning this is very controversial: It may be of interest that a thread exists here that deals with one aspect of this problem. See: Metallic Hydrogen has been created If you want to acquire a preprint you may try here: https://ttasneem.yolasite.com/resources/013017%20Metallic%20Hydrogen%20Article.pdf. This site is unknown but I was able to get it there at this moment of posting.Rioferox wrote:Lets say we have unbreakable box, we fill it up with water and close it, box starts to shrink, therefore it puts water under high pressure would liquid (water or any other) at some turn into solid if only under that pressure, not affected by anything else? Remember, box cannot break and it can shrink infinitely.
These guys at Carnegie are calling the original paper "B**ls**t. Pretty tough talk. The guys in the original paper "slipped and fell", and the pack will surely descend on them and devour them unless they come up with a "cunning plan".Comment on Observation of the Wigner-Huntington transition to metallic hydrogen
Alexander F. Goncharov, Viktor V. Struzhkin (Geophysical Laboratory, Carnegie Institution of Washington, DC)
A recent paper of Dias and Silvera (DS) reports on production of metallic hydrogen in a diamond anvil cell at 495 GPa at 5.5 and 83 K. The results are implied to have a great impact on energy and rocketry. Here we argue that the presented (very scarce) results are contradictory with the presented experimental description making their claims unsupported experimentally. Moreover, the proposed implications are highly speculative making this paper very confusing for a broad audience. Elucidating the claims and the related implications is important for building a coherent picture that is currently emerging as the results of theoretical calculations at various levels and experimental investigations employing static and dynamic compression techniques. There is no doubt that hydrogen metallizes at high pressures. But this does not make all claims about reaching this state immediately valid. Scientific community would like to learn at what conditions hydrogen metallizes, what is the nature of the conducting state and its properties (e.g. superconductivity). Here we argue that the presented data do not provide any reliable information on this.
Downloadable pdf. Water is always the strangest and most atypical of any natural material known. Structures of "water" up to Ice XVI are "known" depending on the temperature and pressure environment (and there are many). It is almost a never ending quest... just a sample (1 MPa is about 10 atmospheres, most important point for us is a triple point around 273K, 1 kPa - note: log pressure scale)...PNAS wrote:Dynamic pressure-induced dendritic and shock crystal growth of ice VI
23 Oct 2005
Abstract: Crystal growth mechanisms are crucial to understanding the complexity of crystal morphologies in nature and advanced technological materials, such as the faceting and dendrites found in snowflakes and the microstructure and associated strength properties of structural and icy planetary materials. In this article, we present observations of pressure-induced ice VI crystal growth, which have been predicted theoretically, but had never been observed experimentally to our knowledge. Under modulated pressure conditions in a dynamic-diamond anvil cell, rough single ice VI crystal initially grows into well defined octahedral crystal facets. However, as the compression rate increases, the crystal surface dramatically changes from rough to facet, and from convex to concave because of a surface instability, and thereby the growth rate suddenly increases by an order of magnitude. Depending on the compression rate, this discontinuous jump in crystal growth rate or “shock crystal growth” eventually produces 2D carpet-type fractal morphology, and moreover dendrites form under sinusoidal compression, whose crystal morphologies are remarkably similar to those predicted in theoretical simulations under a temperature gradient field. The observed strong dependence of the growth mechanism on compression rate, therefore, suggests a different approach to developing a comprehensive understanding of crystal growth dynamics.
dynamic–diamond anvil cell
Users browsing this forum: No registered users and 0 guests