The novel synthesis of the Li mineral jadarite (LiNaSiB 3 O 7 (OH)) Matilda Rhodes a,b , Adrian Hillier b , Caroline Kirk a a School of Chemistry, University of Edinburgh, UK, b ISIS Neutron and Muon Facility, STFC Rutherford Appleton Laboratory, UK Demand for Li ion batteries (LIBs) has grown with use of energy storage facilities, consumer electronics and electric vehicles, and so has demand for battery-grade Li. Jadarite (LiNaSiB 3 O 7 (OH), Li 3.38wt%) 1 has potential as a new Li ore, comparable to current hard rock ores like spodumene (Li 3.73wt%) 2 , which could help meet demand. However, little is known about its formation and Li extraction methodologies are still under development. Lab-based synthesis of jadarite could aid understanding of natural formation and create a supply of jadarite for further experimentation such as for the development of Li extraction methodologies. Here, we present the novel synthesis of jadarite. A precursor was synthesised by the sol-gel method or mechanochemically (Fig.1(a) and (b)). Jadarite was produced by steam crystallisation of the precursor in a dry-gel conversion setup (Fig.1(c)). X-ray Powder Diffraction (XRPD) and Infrared Spectroscopy (IR) confirmed presence of jadarite through comparison of data collected on synthetic and natural samples and results from literature 1,3 . Phases identified by XRPD in synthetic samples included borax (Na 2 B 4 O 7 .10H 2 O), silica (SiO 2 ) and searlesite (NaBSi 2 O 5 (OH) 2 ) (Fig. 1 (d) and (e)), of which the latter two are co-products in nature. Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM-EDS) demonstrated similarities between natural and synthetic samples, in both particle morphology and phase distribution of jadarite, searlesite, and silica. However, all techniques indicated synthetic jadarite was poorly crystalline relative to natural jadarite. Furthermore, single- phase jadarite was only synthesised when tetraethylammonium hydroxide (TEAOH) was added to the reaction mixture (Fig.1(d) and (e)). TEAOH can be removed post-synthesis by heating to 600°C 4 , but this resulted in a phase change and loss of crystalline jadarite. In summary, our results demonstrate the first synthesis of jadarite. Formation of searlesite and silica support hypotheses about jadarite’s natural formation. Furthermore, both single- and mixed-phase samples have scope to improve Li extraction methods, and could be used as a standard to aid development of an efficient and reliable characterisation technique for Li ores. Further experimentation could lead to the synthesis of highly crystalline phase-pure jadarite, without the need for TEAOH.
Figure 1: Jadarite is produced by steam crystallisation of a precursor. The precursor is synthesised either by (a) the sol-gel method or (b) mechanochemically. Steam crystallisation occurs using (c) the dry-gel conversion setup, consisting of a pressure vessel, a PTFE liner, a PTFE beaker, and water. XRD data of synthetic jadarite, crystallised under steam from a precursor synthesised with (d) TEAOH by the sol-gel technique and (e) mechanochemically without TEAOH, demonstrates production of single phase (jadarite) and mixed phase (jadarite, searlesite, borax) samples. References 1. J. Stanley et al. , Eur. J. Mineral ., 2007, 19 , 575–580 2. J. Bowell, L. Lagos, C. R. de los Hoyos and J. Declercq, Elements , 2020, 16 , 259-264
3. S. Whitfield et al. , Acta Crystallogr . Sect. B Struct. Sci ., 2007, 63 , 396–401 4. R. Hari Prasad Rao and M. Matsukata, Chem. Commun. , 1996, 12 , 1441-1442
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