TY - JOUR

T1 - Batisite, Na2BaTi2(Si4O12)O2, from Inagli massif, Aldan, Russia:

T2 - crystal-structure refinement and high-temperature X-ray diffraction study

AU - Zolotarev, Andrey A.

AU - Zhitova, Elena S.

AU - Gabdrakhmanova, Faina A.

AU - Krzhizhanovskaya, Maria G.

AU - Zolotarev, Anatoly A.

AU - Krivovichev, Sergey V.

PY - 2017/12

Y1 - 2017/12

N2 - The crystal structure of batisite, Na2BaTi2 (Si4O12)O2, from the Inagli massif (Aldan, Yakutia, Russia) was refined to R1 = 0.032 for 1449 unique observed reflections. The mineral is orthorhombic, Imma, a = 8.0921(5), b = 10.4751(7), c = 13.9054(9) Å, V = 1178.70(13) Å3. The mineral is based upon three-dimensional titanosilicate framework consisting of chains of corner-sharing MO6 octahedra (M = Ti, Nb, Fe and Zr) and vierer chains of corner-sharing SiO4 tetrahedra. Both chains are parallel to the a axis and are linked by sharing peripheral O atoms. The octahedral chains display disorder of M atoms and bridging O sites related to the out-of-center distortion of octahedral geometry around Ti4+ cations. Electron microprobe analysis gives SiO2 39.46, TiO2 24.66, BaO 21.64, Na2O 7.56, K2O 4.38, Fe2O3 0.90, ZrO2 0.66, Nb2O5 0.36, (H2O)calc 0.58, sum 99.76 wt%. The seven strongest X-ray powder-diffraction lines [listed as d in Å (I) hkl] are: 8.39 (94) 011, 3.386 (56) 031, 3.191 (36) 123, 2.910 (46) 222, 2.896 (100) 024, 2.175 (45) 035, 1.673 (57) 055. The thermal behaviour of batisite in the temperature range from 25 to 950 °C was studied using high-temperature powder X-ray diffraction. The thermal expansion coefficients along the principal crystallographic axes are: αa = 14.4 × 10−6, αb = 8.7 × 10−6, αc = 8.4 × 10−6, αV = 31.5 °C−1 for the temperature range 25–500 °C and αa = 19.6 × 10−6, αb = 9.1 × 10−6, αc = 8.8 × 10−6, αV = 37.6 °C−1 for the temperature range 500–900 °C. The direction of maximal thermal expansion is parallel to the chains of both MO6 octahedra and SiO4 tetrahedra, which can be explained by the stretching of silicate chains due to the increasing thermal vibrations of the Ba2+ cations. At 1000 °C, the titanosilicate framework in batisite collapses with the formation of fresnoite, Ba2TiSi2O7O.

AB - The crystal structure of batisite, Na2BaTi2 (Si4O12)O2, from the Inagli massif (Aldan, Yakutia, Russia) was refined to R1 = 0.032 for 1449 unique observed reflections. The mineral is orthorhombic, Imma, a = 8.0921(5), b = 10.4751(7), c = 13.9054(9) Å, V = 1178.70(13) Å3. The mineral is based upon three-dimensional titanosilicate framework consisting of chains of corner-sharing MO6 octahedra (M = Ti, Nb, Fe and Zr) and vierer chains of corner-sharing SiO4 tetrahedra. Both chains are parallel to the a axis and are linked by sharing peripheral O atoms. The octahedral chains display disorder of M atoms and bridging O sites related to the out-of-center distortion of octahedral geometry around Ti4+ cations. Electron microprobe analysis gives SiO2 39.46, TiO2 24.66, BaO 21.64, Na2O 7.56, K2O 4.38, Fe2O3 0.90, ZrO2 0.66, Nb2O5 0.36, (H2O)calc 0.58, sum 99.76 wt%. The seven strongest X-ray powder-diffraction lines [listed as d in Å (I) hkl] are: 8.39 (94) 011, 3.386 (56) 031, 3.191 (36) 123, 2.910 (46) 222, 2.896 (100) 024, 2.175 (45) 035, 1.673 (57) 055. The thermal behaviour of batisite in the temperature range from 25 to 950 °C was studied using high-temperature powder X-ray diffraction. The thermal expansion coefficients along the principal crystallographic axes are: αa = 14.4 × 10−6, αb = 8.7 × 10−6, αc = 8.4 × 10−6, αV = 31.5 °C−1 for the temperature range 25–500 °C and αa = 19.6 × 10−6, αb = 9.1 × 10−6, αc = 8.8 × 10−6, αV = 37.6 °C−1 for the temperature range 500–900 °C. The direction of maximal thermal expansion is parallel to the chains of both MO6 octahedra and SiO4 tetrahedra, which can be explained by the stretching of silicate chains due to the increasing thermal vibrations of the Ba2+ cations. At 1000 °C, the titanosilicate framework in batisite collapses with the formation of fresnoite, Ba2TiSi2O7O.

KW - Batisite

KW - Crystal structure

KW - Fresnoite

KW - Inagli massif

KW - Shcherbakovite group

KW - Thermal expansion

UR - http://www.scopus.com/inward/record.url?scp=85011711092&partnerID=8YFLogxK

U2 - 10.1007/s00710-017-0497-z

DO - 10.1007/s00710-017-0497-z

M3 - Article

AN - SCOPUS:85011711092

VL - 111

SP - 843

EP - 851

JO - Mineralogy and Petrology

JF - Mineralogy and Petrology

SN - 0930-0708

IS - 6

ER -