Anomalous compression and equation of state of coesite

被引:69
作者
Angel, RJ [1 ]
Mosenfelder, JL [1 ]
Shaw, CSJ [1 ]
机构
[1] Univ Bayreuth, Bayer Geoinst, Blacksburg, VA 24061 USA
关键词
coesite; equation of state; elasticity; bulk modulus;
D O I
10.1016/S0031-9201(01)00184-4
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
The compressional behaviour of coesite has been determined to a maximum pressure of 9.6 GPa by room-temperature single-crystal X-ray diffraction measurements on three crystals selected from two different synthetic samples. There is no evidence for any phase transitions in this pressure range. The new direct measurements show that coesite is approximately 1% denser at 9-10 GPa (at room temperature) than predicted by extrapolation of the previously reported EoS. The volume-pressure data of all three samples cannot be adequately described by any available third-order equation of state. Refined parameters for a fourth-order Birch-Murnaghan EoS are K-T0 = 100.8 +/- 0.5 GPa, K-T0'= 1.8 +/- 0.3 and K-T0"= 0.57 +/- 0.06 GPa(-1). The anomalous positive value of K-T0" appears to be related to the anomalous compression of the c-axis of the structure that exhibits an initial softening with increasing pressure. At pressures in excess of 8 GPa the bulk modulus of coesite is some 20 GPa less than that previously predicted, and the impedence contrast between coesite and stishovite is therefore some 10% greater than would have been estimated on the basis of the previous EoS parameters. (C) 2001 Elsevier Science B.V. All rights reserved.
引用
收藏
页码:71 / 79
页数:9
相关论文
共 28 条
[1]   Diamond-anvil cell for single-crystal x-ray diffraction studies to pressures in excess of 10 GPa [J].
Allan, DR ;
Miletich, R ;
Angel, RJ .
REVIEW OF SCIENTIFIC INSTRUMENTS, 1996, 67 (03) :840-842
[2]   The use of quartz as an internal pressure standard in high-pressure crystallography [J].
Angel, RJ ;
Allan, DR ;
Milletich, R ;
Finger, LW .
JOURNAL OF APPLIED CRYSTALLOGRAPHY, 1997, 30 :461-466
[3]  
ANGEL RJ, 1996, EOS T AGU, V77, pF673
[4]  
ANGEL RJ, 2001, IN PRESS REV MINERAL, V41
[5]  
CHOPIN C, 1983, TERRA COGNITA, V3, P183
[6]   Pressure-induced amorphization in crystalline silica: Soft phonon modes and shear instabilities in coesite [J].
Dean, DW ;
Wentzcovitch, RM ;
Keskar, N ;
Chelikowsky, JR ;
Binggeli, N .
PHYSICAL REVIEW B, 2000, 61 (05) :3303-3309
[7]  
DOWNS RT, 1994, AM MINERAL, V79, P1042
[8]  
GALKIN VM, 1987, GEOKHIMIYA+, P1645
[9]   COESITE IN SUBDUCTED CONTINENTAL-CRUST - P-T HISTORY DEDUCED FROM AN ELASTIC MODEL [J].
GILLET, P ;
INGRIN, J ;
CHOPIN, C .
EARTH AND PLANETARY SCIENCE LETTERS, 1984, 70 (02) :426-436
[10]  
Hemingway BS, 1998, AM MINERAL, V83, P409