A new non-centrosymmetric K2Ca3(CO3)4crystal (P212121,a= 7.3905(2) Å,b= 8.8156(3) Å,c= 16.4817(5) Å) was synthesized in a multi-anvil press at a pressure of 3 GPa and temperature of 975 °C. The compound is homeotypic to A3B2(BO3)4(A = Ca, Sr, Ba; B = REE, Y, Bi) orthoborates with thePnmasymmetry, but is characterized by the non-centrosymmetric arrangement of (CO3) anions within thePnma-pseudosymmetric cation sublattice. K2Ca3(CO3)4represents a pure carbonate member of the extended M5(XO3)4(X = B, C, B/C) structural type, which also includes A3B2(BO3)4orthoborates as well as recently synthesized mixed orthoborate-carbonates of Ba and Sr. Crystallochemical considerations suggest that cation-substituted (REE, Cs, Sr, and Ba) derivatives of K2Ca3(CO3)4can probably be synthesized at significantly lower pressures than 3 GPa, which is required to stabilize the compound itself.
Предметные области OECD FOS+WOS
- 1.04 ХИМИЧЕСКИЕ НАУКИ
- 1.04.FI КРИСТАЛЛОГРАФИЯ