Compression of Na0.4Mg0.6Al1.6Si0.4O4 NAL and Ca-ferrite-type phases
Compression of Na0.4Mg0.6Al1.6Si0.4O4 NAL and Ca-ferrite-type phases
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DOI：
10.1007/s00269-012-0508-x
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发表时间：
2012-04
影响因子：
1.4
通讯作者：
S. Imada;K. Hirose;T. Komabayashi;Toshihiro Suzuki;Y. Ohishi
中科院分区：
文献类型：
--
作者：
S. Imada;K. Hirose;T. Komabayashi;Toshihiro Suzuki;Y. Ohishi
研究了下地幔中两个富铝相--六方新富铝相（NAL）和高压多晶型钙铁氧体型（CF）相在相同成分下的压缩行为。NAL和CF相的体积在室温下得到高达31和134 GPa，分别通过激光退火的金刚石砧室技术和同步辐射X射线衍射测量的组合。用三阶Birch-Murnaghan状态方程对这些压力-体积数据进行拟合，得到NAL相在1bar下的体积模量K 0 = 199（6）GPa，其压力导数K 0 ′ = 5.0（6）; CF相的体积模量K 0 = 169（5）GPa，其压力导数K 0 ′ = 6.3（3）。这些结果表明，体积模量从397增加到407 GPa跨越在43 GPa下从NAL到CF相的相变，其中NAL相完全转变为Na 0.4Mg 0.6Al 1.6Si 0.4O4上的CF相。在整个相变过程中，密度也增加了2.1%。
Compression behaviors of two Al-rich phases in the lower mantle, hexagonal new aluminum-rich (NAL) phase and its high-pressure polymorph Ca-ferrite-type (CF) phase, were examined for identical Na0.4Mg0.6Al1.6Si0.4O4(40 % NaAlSiO4–60 % MgAl2O4) composition. The volumes of the NAL and CF phases were obtained at room temperature up to 31 and 134 GPa, respectively, by a combination of laser-annealed diamond-anvil cell techniques and synchrotron X-ray diffraction measurements. Fitting of the third-order Birch–Murnaghan equation of state to such pressure–volume data yields bulk modulusK0= 199(6) GPa at 1 bar and its pressure derivativeK0′ = 5.0(6) for the NAL phase andK0= 169(5) GPa andK0′ = 6.3(3) for the CF phase. These results indicate that the bulk modulus increases from 397 to 407 GPa across the phase transition from the NAL to CF phase at 43 GPa, where the NAL phase completely transforms into the CF phase on Na0.4Mg0.6Al1.6Si0.4O4. Density also increases by 2.1 % across the phase transition.