1. Navigation through high-dimensional chemical space: discovery of Ba 5 Y 13 [SiO 4 ] 8 O 8.5 and Ba 3 Y 2 [Si 2 O 7 ] 2 .
- Author
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Gulay NL, Zanella M, Robertson CM, Ritchie D, Sonni M, Wright MA, Newnham JA, Hawkins CJ, Whitworth J, Mali BP, Niu H, Dyer MS, Collins CM, Daniels LM, Claridge JB, and Rosseinsky MJ
- Abstract
Two compounds were discovered in the well-studied BaO-Y
2 O3 -SiO2 phase field. Two different experimental routines were used for the exploration of this system due to the differences of synthetic conditions and competition with a glass field. The first phase Ba5 Y13 [SiO4 ]8 O8.5 was isolated through a combination of energy dispersive X-ray spectroscopy analysis and diffraction techniques which guided the exploration. The second phase Ba3 Y2 [Si2 O7 ]2 was located using iterative algorithmic identification of target compositions. The structure solution of the new compounds was aided by continuous rotation electron diffraction, and the structures were refined against combined synchrotron and neutron time-of-flight powder diffraction. Ba5 Y13 [SiO4 ]8 O8.5 crystallizes in I 4̄2 m , a = 18.92732(1), c = 5.357307(6) Å and represents its own structure type which combines elements of structures of known silicates embedded in columns of interconnected yttrium-centred polyhedra characteristic of high-pressure phases. Ba3 Y2 [Si2 O7 ]2 has P 21 symmetry with a pseudo-tetragonal cell ( a = 16.47640(4), b = 9.04150(5), c = 9.04114(7) Å, β = 90.0122(9)°) and is a direct superstructure of the Ca3 BaBi[P2 O7 ]2 structure. Despite the lower symmetry, the structure of Ba3 Y2 [Si2 O7 ]2 retains disorder in both Ba/Y sites and disilicate network, thus presenting a superposition of possible locally-ordered fragments. Ba5 Y13 [SiO4 ]8 O8.5 has low thermal conductivity of 1.04(5) W m-1 K-1 at room temperature. The two discovered phases provide a rich structural platform for further functional material design. The interplay of automated unknown phase composition identification with multiple diffraction methods offers acceleration of the time-consuming exploration of high-dimensional chemical spaces for new structures., Competing Interests: The authors declare no competing interests., (This journal is © The Royal Society of Chemistry.)- Published
- 2024
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