@misc{10481/92103,
year = {2024},
month = {5},
url = {https://hdl.handle.net/10481/92103},
abstract = {The experimental study of depolymerization reaction SiO2 + ZrO2 → ZrSiO4 reveals that melting of quartz and
crystallization of zircon in the presence of water increases at high pressure. The melting rate of quartz is identified
as the rate-determining step of the reaction. In highly polymerized silicates, Si-O-Si bond angles are subject
to alteration under the influence of pressure. This phenomenon is particularly noticeable within the threedimensional
lattice structure of quartz, where each corner of the tetrahedra is shared. Theoretical analysis of
the Si-O-Si bond angle bending demonstrates a change in oxygen hybridization from sp to sp2, favoring larger Si-
O distances. The sp2 hybridization in bridging oxygen promotes acid attack by hydrogen ions of water, resulting
in SiO bond heterolysis in quartz. The depolymerization from tectosilicates to nesosilicates leads to an increase in
oxygen “size” and polarizability, as well of closer packing of oxygen atoms. This change in behavior and packing
of oxygens is further illustrated by the high-pressure-driven transition from tridymite to stishovite. Additionally,
the impact of network-modifying elements on the structure of polymerized silicates is investigated; particularly
those acting as electron donors, which lengthen Si-O distances in quartz. The findings are discussed in relation to
key topics in Earth Sciences, including the crystal chemical basis of the Bowen's reaction series, the “metallization”
in rocky planets and the structural controls of hydrous and dry melting in silicates.},
organization = {This work is a contribution of the research group RNM-179 of the
Junta de Andalucía, Spain. ASN and AC wish to express their gratitude
for the financial support received from projects CGL2012-32169 and
PID2021-126347NB-I00. Funding for open access charge: Universidad de Granada / CBUA. Antonio Sanchez-Navas reports was provided by University of Granada.},
publisher = {Elsevier B.V.},
title = {A case study of depolymerization in silicates: Melting of quartz and zircon crystallization at high pressure},
doi = {10.1016/j.chemgeo.2024.122156},
author = {Sánchez-Navas, Antonio and Melchor, Santiago and Ortega-Castro, Joaquin and Vidal-Daza, Isaac and Castro, Antonio},
}