Thermal expansivity of geikielite and ilmenite utilizing in-situ synchrotron X-ray diffraction at high temperature  

作　　者：Jiamei Song Dawei Fan Shijie Huang Shanrong Zhang Mengzeng Wu Wei Chen Wenge Zhou 

机构地区：[1]Key Laboratory of High-Temperature and High-Pressure Study of the Earth’s Interior,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang550081,Guizhou,China [2]University of Chinese Academy of Sciences,Beijing100049,China [3]Guizhou Polytechnic of Construction,Guiyang 551400,Guizhou,China

出　　处：《Acta Geochimica》2023年第6期988-997,共10页地球化学学报（英文）

基　　金：supported by National Natural Science Foundation of China(U2032118 and 42172048);Guizhou Provincial Science and Technology Projects(QKHPTRCYQK[2023]035 and QKHJC-ZK[2021]ZD042);Hundred Talents Program of the Chinese Academy of Sciences;Guizhou Provincial 2020 and 2021 Science and Technology Subsidies(Nos.GZ2020SIG and GZ2021SIG)。

摘　　要：The unit-cell parameters and volumes of geikielite(MgTiO_(3))and ilmenite(FeTiO_(3))were investigated at high temperatures up to 700 K and ambient pressure,using in-situ angle-dispersive synchrotron X-ray diffraction.No phase transition was detected over the experimental temperature range.Using(Berman in J Petrol29:445-522,1988.10.1093/petrology/29.2.445)equations to fit the temperature-volume data,the volumetric thermal expansion coefficients at ambient conditions(α_(V0))of MgTiO_(3) and FeTiO_(3) were obtained as follows:2.55(6)×10^(-5)K^(-1)and 2.82(10)×10^(-5)K^(-1),respectively.We infer that the larger effective ionic radius of Fe^(2+)(Ⅵ)(0.78 A)than that of Mg^(2+)(Ⅵ)(0.72?)renders FeTiO_(3)has a larger volumetric thermal expansivity than MgTiO_(3).Simultaneously,the refined axial thermal expansion coefficients under ambient conditions areα_(a0)=0.74(3)×10^(-5)K^(-1)andα_(c0)=1.08(5)×10^(-5)K^(-1)for the aaxis and c-axis of MgTiO_(3),respectively,andα_(a0)=0.95(5)×10^(-5)K^(-1)andα_(c0)=0.92(12)×10^(-5)K^(-1)for the aaxis and c-axis of FeTiO_(3),respectively.The axial thermal expansivity of MgTiO_(3) is anisotropic,but that of FeTiO_(3) is nearly isotropic.We infer that the main reason for the different axial thermal expansivity between MgTiO_(3) and FeTiO_(3) is that the thermal expansion mode of the Mg-O bond in MgTiO_(3) is different from that of the Fe-O bonds in FeTiO_(3).

关 键 词：Geikielite ILMENITE Thermal expansion Synchrotron X-ray diffraction High temperature 

分 类 号：P184[天文地球—天文学]