Equation of state and high-pressure phase transitions in lawsonite
Equation of state and high-pressure phase transitions in lawsonite
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硬铝石中的状态方程和高压相变
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
R. Angel
中科院分区：
文献类型：
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作者：
T. B. Ballaran;R. Angel
本文用单晶衍射方法研究了硬硅钙石在室温下的最大压力为9.82GPa时的行为。在大约4GPa下，劳森石经历从具有Cmcm对称性的结构到具有P晶格的另一斜方晶相的相变。这个新相的完全对称性无法确定。过渡涉及小的自发应变在每个三个晶格方向，但没有显着的体积应变。过渡特征似乎是连续的，可能接近二阶。在9.5 GPa以上，进一步过渡到单斜相。根据在9.5GPa以下收集的所有P-V数据确定的两个正交相的EoS参数为V0 =676.10（3）A3，K 0 =122.1（4）GPa和K '=5.6（1）。该新的单晶数据与所有可用的P-V-T数据的拟合提供了硬毛钠石的热EoS的参数：参考温度为298 K时，V0 =676.03（6）A3，KOT =122.8（8）GPa，K '=5.5（2），α 0 =2.63（7）× 10 - 5 K-1，dK/dT=-0.018（5）GPa·K-1。
The behaviour of lawsonite has been studied by single-crystal diffraction to a maximum pressure of 9.82 GPa at room temperature. Lawsonite undergoes a phase transition at approximately 4 GPa from a structure with Cmcm symmetry to another orthorhombic phase with a P lattice. The full symmetry of this new phase could not be determined. The transition involves small spontaneous strains in each of the three lattice directions, but no significant volume strain. The transition character appears to be continuous, probably close to second-order. A further transition to a monoclinic phase occurs above 9.5 GPa. The EoS determined from all of the P-V data collected below 9.5 GPa for the two orthorhombic phases together has parameters V 0 =676.10(3) A 3 , K 0 =122.1(4) GPa and K ’=5.6(1). A fit of this new single-crystal data together with all the P-V-T data available provides the parameters of a thermal EoS of lawsonite: V 0 =676.03(6) A 3 , K OT =122.8(8) GPa, K ’=5.5(2), α 0 =2.63(7)x10 -5 K -1 , d K /dT=-0.018(5) GPa.K -1 for a reference temperature of 298 K.