New Lead Borate Pb2B6O11 and Possibility of Synthesis of Lead Analogue of Maleevite in the PbO–BaO–B2O3–SiO2 System

The PbO–BaO–B 2 O 3 –SiO 2 system is studied using solid-state synthesis and melt crystallization methods and attempts are made to obtain samples of the maleevite (BaB 2 Si 2 O 8 )—lead maleevite (PbB 2 Si 2 O 8 ) series. Due to the strong tendency of Pb-containing borosilicate materials to form glass, a lead-enriched analogue of maleevite is not obtained. In the study, a new lead borate Pb 2 B 6 O 11 (sp. gr. P –1, a = 6.582(1) Å, b = 6.593(1) Å, c = 11.310(2) Å, α = 98.29(1)°, β = 90.65(1)°, γ = 119.10(2)°, V = 422.4(1) Å 3 ) and a series of solid solutions (Ba 1 – x Pb x ) 3 B 6 Si 2 O 16 ( x = 0.2, 0.4, 0.6) are synthesized and characterized for the first time. The layered compound Pb 2 B 6 O 11 has a new structural type, while the solid solution (Ba 1 – x Pb x ) 3 B 6 Si 2 O 16 is a structural analogue of the previously known Ba 3 B 6 Si 2 O 16 .