Understanding the stability and structural diversity of carbonates containing sp3-hybridised carbon in tetrahedral coordination

了解四面体配位中含有 sp3 杂化碳的碳酸盐的稳定性和结构多样性

• 批准号: 466478526
• 负责人: Dr. Lkhamsuren Bayarjargal
• 金额: --
• 依托单位: Institut für Geowissenschaften (IfG)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/466478526?language=en
• 关键词: Understanding; stability; structural; diversity; carbonates

We have recently developed an approach that allowed us to recover Sr2CO4,in which sp3-hy-bridized carbon is four-fold coordinated by oxygen, at ambient conditions. We also obtained with the same approach isostructural Ca2CO4 at moderately high pressures (20 GPa), which, however, amorphises on pressure-release at about 4 GPa. As recent studies by other groups have shown that novel carbonates, i.e. carbonates containing tetrahedrally coordinated sp3-hybridized carbon, can also be formed with iron-, magnesium- and manganese-cations (albeit at very high pressures, p >70 GPa, and as non-quenchable compounds), it now seems plausible that such novel carbonates may be structurally and chemically as diverse as conventional carbonates, especially as CO4 4−-groups may polymerize by corner-sharing, similar to SiO44−groups. We therefore propose a project with the overarching goal to establish a crystal chemical and crystallographic understanding of this new family of novel carbonates with tetrahedrally coordinated sp3-carbon. This proposal encompasses the synthesis of novel carbonates containing Ni2+, Zn2+, Co2+, Cd2+, Eu2+, Ba2+, and Pb2+, by reactions of end-members of conventional carbonates with either an oxide or with CO2 and of selected solid solutions. The project firstly aims to clarify the p,T-conditions at which these novel carbonates can be synthesized in laser-heated diamond anvil cells. Currently, the stability fields even of the few already known novel carbonates are not well constrained and the formation conditions seem to span a really large range from at least 20 - 90 GPa in Sr2CO4 (which probably are neither the lower nor the upper bounds). We then aim to understand the interdependence between composition, synthesis conditions and polymerization of CO44−-groups by combining in situ Raman spectroscopy and synchrotron diffraction, complemented by DFT calculations. Those novel carbonates which can be obtained at moderate pressure (< 20 GPa) and which can be quenched to ambient conditions, e.g. Sr2CO4, will be further studied using milligram-sized samples obtained with large volume presses by NMR, EELS, IXS and relaxation calorimetry in order to provide a basis for an understanding how bonding and properties differ from conventional carbonates.

我们最近开发了一种方法，使我们能够在环境条件下回收Sr 2CO 4，其中sp3-hybridized碳是氧的四重配位。我们还获得了相同的方法，同构Ca 2CO 4在中等高压（20 GPa），然而，无定形的压力释放约4 GPa。由于其他小组最近的研究已经表明，新的碳酸盐，即含有四面体配位的sp3杂化碳的碳酸盐，也可以与铁、镁和锰阳离子形成（尽管在非常高的压力下，p >70 GPa，并且作为不可淬灭的化合物），现在似乎合理的是，这种新型碳酸酯可以在结构上和化学上与常规碳酸酯一样多样，特别是CO 4 4 −基团可以通过角共享来取代，类似于SiO 44 −基团。因此，我们提出了一个项目的总体目标是建立一个晶体化学和晶体学的理解，这个新的家庭的新的碳酸酯与四面体协调的sp3-碳。该建议包括通过常规碳酸盐的端元与氧化物或与CO2以及所选择的固溶体的反应来合成含有Ni 2+、Zn 2+、Co 2+、Cd 2+、Eu 2+、Ba 2+和Pb 2+的新型碳酸盐。该项目首先旨在澄清这些新型碳酸盐可以在激光加热金刚石对顶砧单元中合成的p，T条件。目前，即使是少数已知的新型碳酸盐的稳定性场也没有得到很好的约束，并且形成条件似乎跨越了Sr 2CO 4中至少20 - 90 GPa的非常大的范围（这可能既不是下限也不是上限）。然后，我们的目标是通过结合原位拉曼光谱和同步辐射衍射，并辅以DFT计算，了解组成，合成条件和CO 44 −-基团聚合之间的相互依赖关系。这些新的碳酸盐，可以在中等压力（< 20 GPa）下获得，并可以淬火到环境条件下，例如Sr 2CO 4，将进一步研究使用毫克大小的样品与大容量的压力通过NMR，EELS，IXS和弛豫量热法，以提供一个基础，了解如何键合和性能不同于传统的碳酸盐。