The influence of Ca–Mg disorder on the growth of dolomite: a computational study,CrystEngComm

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The influence of Ca–Mg disorder on the growth of dolomite: a computational study
CrystEngComm ( IF 2.6 ) Pub Date : 2020-06-18 , DOI: 10.1039/d0ce00663g
M. Bruno _{1,

2,

3,

4,

5} , S. Ghignone _{1,

2,

3,

4} , L. Pastero _{1,

2,

3,

4,

5} , D. Aquilano _{1,

2,

3,

4}

Affiliation

We performed empirical calculations at 0 K on the (10.4) slabs of dolomite with increasing thickness and different Ca²⁺–Mg²⁺ distributions (i.e., different degrees of structural disorder) in the 10.4 layers forming the slab. The energy of the isolated (10.4) dolomite slabs and (10.4) dolomite slabs in epitaxy with the (10.4) calcite slabs was determined. In particular, the (i) average potential energy, (ii) specific adhesion energy and (iii) excess free energy due to the presence of the interfaces were calculated for all the systems investigated. These data allowed us to propose a new growth model for primary dolomite, which hypothesizes that dolomite forms from a Ca²⁺–Mg²⁺-rich fluid by initially nucleating small calcite crystals, which act as substrates for successive dolomite formation. Moreover, our calculations suggest that the dolomite layers forming at the dolomite/calcite and dolomite/solution interfaces are disordered with increasing adhesion energy and decreasing surface energy. Then, a disordered dolomite/calcite interface seems to promote dolomite growth.

中文翻译：

Ca–Mg紊乱对白云石生长的影响：计算研究

我们在厚度为10.4的白云岩厚板和不同Ca ²⁺ -Mg ²⁺分布（即不同程度的结构紊乱）的（10.4）厚板的0 K处进行了经验计算。确定了孤立的（10.4）白云石板和（10.4）白云石板的外延与（10.4）方解石板的能量。特别地，对于所有研究的系统，计算（i）平均势能，（ii）比粘附能和（iii）由于存在界面而产生的过量自由能。这些数据使我们能够为原生白云石提出新的生长模型，该模型假设白云石由Ca ²⁺ –Mg ^2+形成。首先使小方解石晶体成核，从而形成连续白云石形成的基质。此外，我们的计算表明在白云石/方解石和白云石/溶液界面形成的白云石层随着粘附能的增加和表面能的降低而无序。然后，无序的白云石/方解石界面似乎促进了白云石的生长。

更新日期：2020-07-27

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