Structure and electrical properties of crystalline and glassy Ag2PbP2O7

Abstract Single crystals of Ag 2 PbP 2 O 7 have been prepared by melting of the crystalline phase under phosphate flux. Ag 2 PbP 2 O 7 , isotype of Na 2 PbP 2 O 7 , is of triclinic symmetry with the space group P(−1) ( Z =2). The unit cell parameters are: a =5.502(6) A, b =7.008(8) A, c =10.018(9) A, α =106.63(6)°, β =93.89(7)°, γ =110,68(6)°. The lattice of Ag 2 PbP 2 O 7 consists of corner-shared structural units {Pb 2 P 4 O 14 } 4− , which form ribbons parallel to the [010] direction. The {Pb 2 P 4 O 14 } 4− units result from the association of corner-shared PbO 5 polyhedra and P 2 O 7 pyrophosphate groups. The ribbons are interconnected by Pb–O–P bridges in the [100] direction and form lamina parallel to (001) plan. Silver atoms are located between two alternating lamina. Glasses with the same composition as the crystalline phase have been synthesized. A study of transport properties of Ag 2 PbP 2 O 7 in the crystalline and glassy forms is reported.