High-pressure behavior and phase transition of jadarite, a promising B and Li mineral commodity

The high-pressure behavior of a natural jadarite (ideally LiNaSiB3O7(OH), a similar to 6.76 A, b similar to 13.80 A, c similar to 7.69 A, beta = 124.09 degrees, space group P2(1)/c) has been studied by in situ single-crystal and powder synchrotron X-ray diffraction up to 20 GPa, with a diamond anvil cell and using He as a hydrostatic pressure-transmitting fluid. Between 16.57(5) and 17.04(5) GPa, jadarite undergoes a first-order iso-symmetric phase transition, which is reconstructive in character, with a Delta V of approximately -3%. The structure of the high-pressure polymorph was solved and refined (to R-1 similar to 4%). The isothermal bulk modulus of the low-P polymorph of jadarite is K-V(0) =( )55.0(5) GPa (beta(V)(0) = 0.0182(2) GPa(-1)), and its P-derivative is 3.84(9). The compressional anisotropy, derived along the three main crystallographic directions, is modest, with beta(a)(0):beta(b)(0):beta(c)(0) = 1.23:1:1.23. The P-induced deformation mechanisms at the atomic scale, which lead to phase transition, are described.