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A new superstructure was found in bafertisite[(Ba_(0.98)Na_(0.02))_(1.00)(Fe_(1.71)Mn_(0.26)Mg_(0.01))_(1.98) TiO [(Si_(1.82)Ti_(0.04)Al_(0.03)Cr_(0.01))_(1.90)O_7](OH_(1.40)F_(0.53)Cl_(0.03))_(1.96)]from Donghai County,Jiangsu Province,China.The occurrence of the superstructure reflections were observed by single crystal diffraction using a SMAR APEX CCD.The a~*,b~* and c~* axis directions revealed extra weak reflection spots of the superstructure.The apparent 2a,2b and 2c superstructure is monoclinic with unit cell a=10.6502(15) A,b= 13.7233(19)A,c=21.6897(3)A,α=90°,β=94.698(3)°,γ=90°,space group Cm,Z=16.If c~* extra weak reflections are ignored,the secondary supercell gave a cell a=10.6548(15)A,b=13.7284(19)A,c = 11.6900(17)A,α=90°,β=112.322(28)°,γ=90°,space group Cm,Z=8.The basic subcell was obtained by ignoring all extra weak reflection spots and gave:a=5.3249(17)A,b=6.8669(22)A,c=10.8709(36) A,α=90°,β=94.740(62)°,γ=90°,space P2_1/m,Z=2.The superstructure has been refined to R = 0.063 for 7805[R_((int))= 0.0266]unique reflections I>2δ(I).The structure consists of an octahedra(O) sheet sandwiched between two heteropolyhedral(H) sheets.These sheets consist of Ti-octahedra and twin tetrahedral disilicate groups[Si_2O_4].The O sheet comprises(Fe,Mg)O_4 octahedra.The large Ba cation is located in the interlayer area.The refined structure shows Fe,Mg are partly ordered.The shifting of the TiO_6 octahedron and SiO_4 tetrahedron sites in the sheet may be a consequence of the superstructure.
A new superstructure was found in bafertisite [(Ba_ (0.98) Na_ (0.02)) _ (1.00) (Fe_ (1.71) Mn_ (0.26) Mg_ (0.01) ) Al_ (0.03) Cr_ (0.01)) _ (1.90) O_7] (OH_ (1.40) F_ (0.53) Cl_ (0.03)) _ (1.96)] from Donghai County, Jiangsu Province, China.The occurrence of the superstructure reflections were observed by single crystal diffraction using a SMAR APEX CCD. a ~ *, b ~ * and c ~ * axis directions revealed extra extraneous reflection spots of the superstructure. apparent 2a, 2b and 2c superstructure is monoclinic with unit cell a = 10.6502 (15) A, b = 13.7233 (19) A, c = 21.6897 (3) A, α = 90 °, β = 94.698 (3) °, γ = 90 °, space group Cm, Z = a * = 9, and α = 90 °, β = 112.322 (28) °. * The extra weak reflections are ignored, the secondary supercells gave a cell a = 10.6548 A, b = 13.7284 A, c = 11.6900 A, , γ = 90 °, space group Cm, Z = 8. The basic subcell was obtained by ignoring all extra weak reflection spots and gave: a = 5.3249 (17) A, b = 6.8669 (22) A, c = 10.8709 ) A, α = 90 °, β = 94.740 (62) °, γ = 90 °, space P2_1 / m, Z = 2. The superstructure has bee unique reflections I> 2δ (I). The structure consists of an octahedra (O) sheet sandwiched between two heteropolyhedral (H) sheets. These sheets consist of Ti-octahedra and twin tetrahedral disilicate groups [Si_2O_4]. The O sheet comprises (Fe, Mg) O_4 octahedra. The large Ba cation is located in the interlayer area. The refined structure shows Fe, Mg are partially ordered. Shifting the the TiO_6 octahedron and SiO_4 tetrahedron sites in the sheet may be a consequence of the superstructure.