On the labyrinthine crystal chemistry of the hydrous borate MgB3O3(OH)5•5H2O (inderite)

Boron is a strategic element for a series of technologically and industrially relevant processes and products, from eye drops to fertilisers. For its neutron-absorbing properties, 10B is also used in the production of radiation-shielding building materials, in particular B-bearing Portland cements, relevant for applications in nuclear medicine and nuclear power plants. However, the most used natural borates (i.e., borax) have proved to induce a negative effect on setting and hardening (with an anomalous extension of the cement hydration period), coupled with a lowering of durability of concretes (due to the high Na-content). We are investigating the chemical stability and high-T/high-P crystal-chemistry of inderite [ideally MgB3O3(OH)5•5H2O], which contains 37 wt% B2O3 and 48 wt% H2O, with a multi-methodological approach: a SC neutron diffraction experiment is necessary to obtain a full structural model of inderite, with an unambiguous location of all the H sites (presumably 15 crystallographically independent H sites into the structure) and the description of the complex H-bonding network.