... structures of Ag- and Cu-exchanged forms of lomonosovite and Ag-exchanged form of murmanite were studied by single-crystal X-ray diffraction. The topology of the main structural unit, the HOH block, remains unchanged in cation-exchanged forms as compared to the initial lomonosovite Na 4 Ti 4 (Si 2 O 7 ) 2 O4...

...F. Cámara; E. Sokolova; F. C. Hawthorne; Y. Abdu Abstract The crystal structures of lomonosovite, ideally Na 10 Ti 4 (Si 2 O 7 ) 2 (PO 4 ) 2 O 4 , a = 5.4170(7) Å, b = 7.1190(9) Å, c = 14.487(2) Å, α = 99.957(3)°, β = 96.711(3)°, γ = 90.360(3)°, V = 546.28(4) Å 3 , D calc. = 3.175 g cm -3...

.... This model has been refined by the distance least-squares technique (DLS program) and tested against calculated powder-diffraction and SAED patterns. The structure of bornemanite can be described as a [001] stacking of heterophyllosilicate layers, where lomonosovite and seidozerite contents alternate...

... of Na polyhedra and P tetrahedra which ideally gives {Na 2 □ 4 [PO 3 (OH)][PO 2 (OH) 2 ]} pfu . Betalomonosovite is an Na-poor OH-bearing analogue of lomonosovite, Na 10 Ti 4 (Si 2 O 7 ) 2 (PO 4 ) 2 O 4 . In the betalomonosovite structure, there is less Na in the I block and in the TS block when...

.... Betalomonosovite is a transformation product of lomonosovite, Na 10 Ti 4 (Si 2 O 7 ) 2 (PO 4 ) 2 O 4 , due to the leaching of Na and protonation of O atoms of phosphate groups and Ti–O–Ti bridges. Distinctive features of betalomonosovite are: (a) the presence of H + in the form of species-defining acid phosphate...