Crystal Structures of Biotite at High Temperatures and of Heat-Treated Biotite using Neutron Powder Diffraction
Crystal Structures of Biotite at High Temperatures and of Heat-Treated Biotite using Neutron Powder Diffraction
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DOI：
10.1346/ccmn.2003.0510506
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发表时间：
2003-10
影响因子：
2.2
通讯作者：
C. Chon;Shin ae Kim;H. Moon
中科院分区：
文献类型：
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作者：
C. Chon;Shin ae Kim;H. Moon
安大略省Bancroft的黑云母- M的晶体结构，公式为：美元\离开({{{rm \ {K}} _ {1.96}} {\ rm {N}} {{\ rm{一}}_ {0.13}}{\ rm {C}} {{\ rm{一}}_{0.01}}}\)\离开({{\ rm {M}} {{\ rm {g}} _ {3.15}} {\ rm{菲}}_ {2.59}^ {2 +}{\ rm {T}} {{\ rm{我}}_ {0.17}}{\ rm {M}} {{\ rm {N}} _{0.09}}} \) \离开({{\ rm{年代}}{{\ rm{我}}_ {5.98}}{\ rm{一}}{{\ rm {l}} _ {1.92}} {\ rm {T}} {{\ rm{我}}_{0.10}}}\右){{\ rm {O}} _{20}} \离开[{{{\离开({{\ rm{哦}}}\右)}_ {1.47}}{{\ rm {F}} _{1.98}}} \右]美元(K1.96Na0.13Ca0.01) (Mg3.15Fe2.592 + Ti0.17Mn0.09) (Si5.98Al1.92Ti0.10) O20 [1.47 (OH) f1.98],在20 ~ 900℃的原位温度下，采用高分辨率中子粉末衍射，采用Rietveld精化法测定。用电炉在空气中加热到400 ~ 900℃的样品的室温结构也得到了细化。细化后的晶体结构RP为2.98 ~ 5.06%，Rwp为3.84 ~ 6.77%。对于真空中原位加热实验，单元胞尺寸在600°C时线性增加。c轴的线性膨胀系数为1.65 × 10−5°c−1，a和b轴的线性膨胀系数分别为4.44 × 10−6°c−1和5.21 × 10−6°c−1。因此，当温度达到600℃时，单体体积的增加主要是沿C轴方向发生的，这是由于K配位球沿该方向的膨胀。所有K−O键的结果都是根据晶格分量和结构应变的内部分量来分析的。随着温度的升高，双方畸变从20℃时的3.76降低到600℃时的1.95，这是由于短键膨胀而长键收缩。层间分离的增加和层间八面体展平角的减小证实了层间区域发生了c主导的膨胀。在原位加热的样品中，当温度超过400℃时，电池尺寸急剧减小。由于八面体铁的氧化，八面体薄片厚度和平均距离线性减小。然而，当温度超过400℃时，层间分离和平均距离减小。在400℃时，脱羟基作用开始增加，层间区域变得更加狭窄。由于脱羟基作用，随着温度的升高，整个细胞参数迅速下降。K−O键中较大的内部应变分量也导致相当大的双方畸变增加（400°C时为3.57°，900°C时为6.15°）。
The crystal structure of biotite-1 M from Bancroft, Ontario, with the formula: $\left( {{{\rm{K}}_{1.96}}{\rm{N}}{{\rm{a}}_{0.13}}{\rm{C}}{{\rm{a}}_{0.01}}} \right)\left( {{\rm{M}}{{\rm{g}}_{3.15}}{\rm{Fe}}_{2.59}^{2 + }{\rm{T}}{{\rm{i}}_{0.17}}{\rm{M}}{{\rm{n}}_{0.09}}} \right)\left( {{\rm{S}}{{\rm{i}}_{5.98}}{\rm{A}}{{\rm{l}}_{1.92}}{\rm{T}}{{\rm{i}}_{0.10}}} \right){{\rm{O}}_{20}}\left[ {{{\left( {{\rm{OH}}} \right)}_{1.47}}{{\rm{F}}_{1.98}}} \right]$(K1.96Na0.13Ca0.01)(Mg3.15Fe2.592+Ti0.17Mn0.09)(Si5.98Al1.92Ti0.10)O20[(OH)1.47F1.98], was determined by Rietveld refinement using high-resolution neutron powder diffraction at in situ temperatures ranging from 20 to 900°C. The room-temperature structure of the samples heated to between 400 and 900°C using an electric furnace in air was also refined. The crystal structures were refined to an RP of 2.98 — 5.06% and Rwp of 3.84–6.77%. For the in situ heating experiments in a vacuum, the unit-cell dimensions increased linearly to 600°C. The linear expansion coefficient for the c axis was 1.65 × 10−5°C−1, while those for the a and b dimensions were 4.44 × 10−6°C−1 and 5.21 × 10−6°C−1, respectively. Accordingly, the increase in the unit-cell volume up to 600 C occurred mainly along the c axis, resulting from the expansion in the K coordination sphere along that direction. Results for all K−O bonds were analyzed in terms of the lattice component and an inner component of the structural strain. The ditrigonal distortion decreased (3.76 at 20°C to 1.95 at 600°C) with temperature, because the shorter bonds expanded and the longer bonds contracted. The increase in the interlayer separation and the decrease in the interlayer octahedral flattening angle confirmed that the c-dominated expansion occurred in the interlayer region. In the case of the ex situ-heated samples, the cell dimensions decreased sharply at temperatures over 400 C. The octahedral sheet thickness and mean distance decreased linearly due to oxidation of octahedral Fe. However, the interlayer separation and mean distance decreased at temperatures over 400°C. At 400°C, dehydroxylation began to increase and interlayer regions became more constricted. The overall cell parameters decreased rapidly with increasing temperatures due to dehydroxylation. The large inner strain components in the K−O bonds also resulted in an increase in the considerable ditrigonal distortion (3.57° at 400°C to 6.15° at 900°C).