Phase diagram of ammonia up to 200 GPa, search for ionic phase. Ionic and superionic conductivity of hot solid ammonia

我们将在实验上研究氨在未探索的兆巴压力范围内的转化，预测了一些不寻常的现象。浓氨NH3作为类似于水的氢键固体的原型具有根本意义。但与水相反，它可能在P>90 GPa的压力下形成由NH+4和NH-2离子交替层组成的“铵酰胺”离子固体。我们将在100-200 GPa范围内通过X射线、衍射、拉曼散射和红外吸收研究来寻找离子相。 NH3冰的另一种新状态是在高压和高温下预测的：超离子固相，氢通过剩余氮离子的晶格扩散非常快。电子相是一种独特的物质状态，其中化学键非常迅速地断裂和重新形成。这个阶段与行星物理学特别相关，因为由水、甲烷和氨组成的冰层被认为是天王星和海王星测量的磁场的来源。在本项目中，我们将在60 - 120 GPa和300-2500 K的压力-温度范围内，通过在激光加热的金刚石对顶砧单元中直接测量质子电导率来寻找氨冰的离子电导率。

We will experimentally study transformations in ammonia at unexplored range of megabar pressures where a number of unusual phenomena are predicted. Dense ammonia NH3 is of fundamental interest as an archetype of hydrogen-bonded solids similar to water. But in contrast to water it might form at pressures P>90 GPa “ammonium amide” ionic solid consisting of alternate layers of NH+4 and NH-2 ions. We will search for the ionic phase by study X-ray, diffraction, Raman scattering and infrared absorption at 100-200 GPa. Another new state of NH3 ice was predicted under high pressures and temperatures: superionic solid phase with exceptionally fast hydrogen diffusion through a crystalline lattice of the remaining nitrogen ions. Superionic phase is a unique state of matter in which chemical bonds are breaking and reforming very rapidly. This phase is particularly relevant to planetary physics because the ice layer consisted of water, methane and ammonia is considered to be the source of the magnetic fields measured at Uranus and Neptune. In this project we will search for ionic conductivity of ammonia ice in the 60 – 120 GPa and 300-2500 K pressure-temperature domain by direct measuring protonic conductivity with impedance spectroscopy in the laser heated diamond anvil cell.