Stability and breakdown of Ca13CO3 melt associated with formation of 13C-diamond in static high pressure experiments up to 43GPa and 3900K
摘要:
Melting of calcium carbonate (CaCO3)-C-13, stability of the melt and its decomposition were studied in static high pressure experiments at pressures of 11-43 GPa and temperatures of 1600-3900 K using diamond anvil cell technique with laser heating. We observed formation of C-13-graphite (below 16 GPa) and C-13-diamond (between 16 and 43 GPa) on decomposition of the (CaCO3)-C-13 melt at temperatures above 3400 K. At temperatures below 3400 K congruent melting of calcium carbonate was confirmed. The experimental results were applied to construction of the phase diagram of CaCO3 up to 43 GPa and 3900 K focusing at the melting curve of calcium carbonate and the decomposition phase boundary of CaCO3 melt. (C) 2012 Elsevier Inc. All rights reserved.
通过无定形碳酸钙结晶将结构不相容的 Ba 2+结合到方解石中,即使在室温下也会导致 X 射线衍射图案中 113 反射的消光。最近,这种现象被假设为源自 Ba 掺杂方解石中 CO 3 2-的静态无序,导致晶胞体积显着增加。为了通过实验阐明这一假设,研究了掺杂Ba的方解石样品中CO 3 2-的行为和局部结构。粉末 X 射线衍射 (XRD) 和差示扫描量热法 (DSC) 表明,掺杂 Ba 的方解石中的 CO 3 2-离子是无序的,即使在 91K 时也是如此。13C MAS NMR 光谱表明方解石中的 Ba 原子被随机取代为 Ca 原子。Ca K 边 X 射线吸收精细结构 (XAFS) 和 IR 吸收光谱表明随着 Ba 含量的增加,CO 3 2-对称性降低。通过将不相容的 Ba 2+掺入方解石中,这些局部结构发生变化,导致室温下CO 3 2-的静态无序。
Incorporation of structurally incompatible Ba2+ into calcite by crystallization via amorphouscalciumcarbonate induces extinction of 113 reflection in X-ray diffraction patterns even at room temperature. Recently, this phenomenon has been hypothesized as deriving from the static disorder of CO32− in Ba-doped calcite, creating a marked increase in the unit-cell volume. To clarify this hypothesis by
通过无定形碳酸钙结晶将结构不相容的 Ba 2+结合到方解石中,即使在室温下也会导致 X 射线衍射图案中 113 反射的消光。最近,这种现象被假设为源自 Ba 掺杂方解石中 CO 3 2-的静态无序,导致晶胞体积显着增加。为了通过实验阐明这一假设,研究了掺杂Ba的方解石样品中CO 3 2-的行为和局部结构。粉末 X 射线衍射 (XRD) 和差示扫描量热法 (DSC) 表明,掺杂 Ba 的方解石中的 CO 3 2-离子是无序的,即使在 91K 时也是如此。13C MAS NMR 光谱表明方解石中的 Ba 原子被随机取代为 Ca 原子。Ca K 边 X 射线吸收精细结构 (XAFS) 和 IR 吸收光谱表明随着 Ba 含量的增加,CO 3 2-对称性降低。通过将不相容的 Ba 2+掺入方解石中,这些局部结构发生变化,导致室温下CO 3 2-的静态无序。
Stability and breakdown of Ca13CO3 melt associated with formation of 13C-diamond in static high pressure experiments up to 43GPa and 3900K
Melting of calcium carbonate (CaCO3)-C-13, stability of the melt and its decomposition were studied in static high pressure experiments at pressures of 11-43 GPa and temperatures of 1600-3900 K using diamond anvil cell technique with laser heating. We observed formation of C-13-graphite (below 16 GPa) and C-13-diamond (between 16 and 43 GPa) on decomposition of the (CaCO3)-C-13 melt at temperatures above 3400 K. At temperatures below 3400 K congruent melting of calcium carbonate was confirmed. The experimental results were applied to construction of the phase diagram of CaCO3 up to 43 GPa and 3900 K focusing at the melting curve of calcium carbonate and the decomposition phase boundary of CaCO3 melt. (C) 2012 Elsevier Inc. All rights reserved.