Combined shock-wave synthesis of noble spinel and laves cubic phase

Abstract

The paper described the shock-wave synthesis of high-pressure high-temperature mineral MgAl 2 O 4 with the parameter a = 8.085(3) Å and the Laves phase MgCu 2 with a = 7.076(2) Å from a mixture of MgO and aluminum powder placed into a copper insert inside a steel conservation ampoule. Spinel MgAl 2 O 4 with a smaller lattice parameter a = 8.0798 Å has been formed in an aluminum insert cup.

Shock-wave synthesis of high-density modifications of zinc oxide (review)

“…The experimental density of red ZnO crystals is identical to that of zincite 5.63 -5.67 g/cm 3 . The x-ray diffraction data of this ZnO correspond to, just as for zincite, a hexagonal unit cell with a = 3.243(7) Å and c/a = 1.605 Å.…”

“…The high-pressure phase of SiO 2 with stishovite structure was found in the products of decomposition of the substances Al 2 SiO 5 , Mg 2 SiO 4 , and ZrSiO 4 subjected to shockwave compression. The high-pressure phase of BN was synthesized with shock-wave compression of the compound BH 3 × NH 3 . The x-ray diffraction identification of these phases attests to the formation of quite large crystallites (> 100 Å).…”

“…The parameters of the orthorhombic subcell were determined from the indexed lines: a = 5.997(2) Å, b = 5.267(1) Å, c = 2.369(1) Å, V = 74.8 Å 3 , Z = 4, r calc = 7.222 g/cm 3 . The x-ray diffraction data for ZnO(III) were indexed in the primitive monoclinic unit cell with a = 7.932 (8) In summary, three new polymorphous modifications of zinc oxide were synthesized by dynamic compression of zincite (28 GPa).…”

“…In a previous work [3] the present authors were able to synthesize simultaneously two compounds -high-temperature and pressure mineral MgAl 2 O 4 and high-density cubic Laves phase MgCu 2 -with the Fedorov group Fd3m by shock-wave compression of three substances (Al, MgO, Cu) with the space symmetry group Fm3m according to the reaction 2Al + 4MgO + 6Cu ® MgAl 2 O 4 + 3MgCu 2 .…”

Synthesis of nonstoichiometric aluminomagnesium spinel with a tetragonal lattice (review)

“…The noble spinel MgAl 2 O 4 -a mineral of high pressures and temperatures [1] -is encountered in the form of single, developed, octahedral crystals in metamorphic, highmagnesium rocks, has high hardness (7.5 -8.0 on the Moos scale), and despite the low atomic mass of magnesium and aluminum, high density (3.59 g/cm 3 ). Due to the possibility of substituting Mg 2+ and Al 3+ with transition metal ions (Mg 2+ ® Fe 2+ , Fe 3+ , Mn 2+ , Co 2+ ; Al 3+ ® Fe 3+ , Cr 3+ , V 3+ , Mn 3+ , Fe 2+ ), many varieties are found in nature [2].…”