Nanostructuring in the Process of the Formation
of Mixed-Anion Compounds:
Rare-Earth Borogermanates, Germanophosphates,
and Borotungstates

G. A. Bandurkin, N. N. Chudinova, G. V. Lysanova, K. K. Palkina,
E. V. Murashova, V. A. Krut’ko, and G. M. Balagina

Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia

Received February 10, 2005

Abstract—Specific features of the textures (the preferred orientation of the nanometer building blocks) in the
structures of mixed-anion compounds—rare-earth borogermanates, germanophosphates, and borotungstates
that arise from the acid–base interaction in the Ln₂O₃–B₂O₃–GeO₂ , Ln₂O₃–GeO₂–P₂O₅ , and Ln₂O₃–B₂O₃–
WO₃ systems (Ln = La–Gd)—have been studied. Based on characteristic texture traits, the mixed-anion com-
pounds of early rare-earth elements can be divided into three groups: (i) Ln₂O₃ : E_xO_y > 1, (ii) Ln₂O₃ : E_xO_y= 1,
and (iii) Ln₂O₃ : E_xO_y < 1. Because of the dominant structural effect of the basic oxide Ln₂O₃ in the compounds
of the first group, the structures of Nd₁₄O₈(BO₃)₆(GeO₄)₂ and Pr₁₁O₁₀(GeO₄)(PO₄)₃ are composed of infinite
[LnO_n] bands and layers and discrete groups [EO_m] located in the interband and interlayer spaces. The dominant
structural effect of the acid oxides [E_xO_y] in the compounds of the third group leads to the appearance of ring
textures composed of [LnO_n], as well as to the appearance of chains and networks composed of [EO_m], in the
structures of Ln(BGeO₅) and Ln(BO₂)(WO₄).

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