的一个更有趣的例子钻石维护其晶格中讨论高压(答案)(https://space.stackexchange.com/questions/18374/what-forms-of-water-ice-have-been-observed-and-verified-in-the-solar-system/33570 # 33570)从太空探索。第七把短暂,冰夹杂物中发现了钻石在地球表面尽管这个阶段的水需要GPa压力水平。在这种情况下所需的压力一定是继承了在金刚石晶格内发现了冰,和晶格参数的计算压力确实是8 - 11 GPa之间冰七世将是稳定的。倾向于保持内部压力并不完全独特的钻石。任何固体形成的压力下能够保持这样的压力在其晶格内部。然而,如果周围的压力释放后,材料也会变形,以减轻内部压力。大致上,只有一个类似数量的压力屈服强度(通常是远低于体积弹性模量)预计将被保留。这背后的力学结果描述如下。对大多数固体这个极限是如此之低,夹杂物最终在他们的“正常”低压阶段,不是很有趣。钻石的独特之处是它的优越的力量:[1]][·劳夫(https://doi.org/10.1063/1.326378)提供35 GPa的屈服强度,使其rentain足够的内部压力(如果它是形成在这种压力)来稳定冰七世,perovskite-structured硅酸盐等。* *参考* *阿瑟·l·劳夫(1979)。 "On the yield strength of diamond". _Journal of Applied Physics_ **50**, 3354. https://doi.org/10.1063/1.326378 ---- **The pressure's on: How a solid matrix retains pressure ... or not** Consider a spherical particle of radius $r_p$ exerting pressure $P$ on a surrounding solid matrix. In the absence of a counterbalancing pressure from the outside, the imposed pressure from within generates a compressive stress $\sigma_c$ in the radial direction and a tensile stress $\sigma_t$ in the two orthogonal directions (along spheres concentric with the particle) through the volune of the surrounding solid. As shown in the picture below, both components decrease with the cube of the distance from the particle, and so have maximum magnitude at the particle surface. There the negative compressive stress is $-P$ and the positive tensile stress is $+P/2$. [![enter image description here][2]][2] We can apply the Von Mises yield criterion which states that the surrounding matrix yields, thus reducing the retained pressure, when $(\sigma_1-\sigma_2)^2+(\sigma_2-\sigma_3)^2+(\sigma_3-\sigma_1)^2\ge2(YS)^2$ where $\sigma_1,\sigma_2,\sigma_3$ are the three orthogonal principal components of the stress tensor. Here $\sigma_1=\sigma_c=-P$ and $\sigma_2=\sigma_3=\sigma_t=+P/2$, from which the yield criterion then becomes $P\ge(2/3)(YS)$ For a diamond lattice with a yield strength of 35 GPa this means the diamond can sustain a pressure up to 23 GPa, as quoted in the main text, around an Ice VII inclusions, whereas most other minerals would have yield stresses well below 1 GPa and thus fail to retain enough pressure to sustain Ice VII or other GPa-pressure phase inclusions. [1]: https://i.stack.imgur.com/EE5iB.png [2]: https://i.stack.imgur.com/ksIa7.png