Single-crystal structure and theoretical calculations of the second ternary tellurium borate Te2B2O7

We present the high-pressure/high-temperature synthesis (10 GPa, 1073 K) of the second known tellurium borate Te2B2O7. It crystallizes in a unique crystal structure with the lattice parameters a = 1876.54(5) pm, b = 1170.11 (3) pm, c = 440.43(1) pm, V = 0.967(1) nm3, and eight formula units (Z = 8) per unit cell in the orthorhombic non-centrosymmetric space group Pna21 (no. 33). The structure contains only corner connected tetrahedral [BO4]5- and bisphenoidal [TeO4]4-units. The structure is discussed in detail and theoretical calculations including a visualization of the electron localization function have been carried out.

Automated summary

We have successfully synthesized a new tellurium borate crystal under high-pressure and high-temperature conditions. The crystal structure and theoretical calculations have been thoroughly discussed.