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1.
PbAl_3(PO_4)_2(OH,H_2O)_6,an important environmental mineral,is in-situ studied by synchrotron x-ray diffraction(XRD)and Raman scattering combined with diamond anvil cells(DACs)at pressures up to~11.0 GPa and room temperature.The XRD results indicate that plumbogummite does not undergo a phase transition between 0 GPa and 10.9 GPa.Moreover,the c axis is more compressible than the a axis,revealing its anisotropic behavior.The pressure-volume data are fitted to the third-order Birch-Murnaghan equation of state to yield the plumbogummite bulk modulus K_0 of 68(1)GPa and K'_0 of 6.1.The [PO_4]~(3-)and [HPO_4]~(2-) Raman vibrational modes exhibit scale nearly linearly as a function of pressure.The [PO4]~(3-) stretching modes are generally more sensitive to pressure than the bending modes.The Grüneisen parameters range from -0.07 to 1.19,with an arithmetic mean of approximately 0.39.  相似文献   
2.
 采用固态高温烧结反应方法,成功合成出了陨硅镍铁石样品(Fe0.03Ni0.97)8(Si0.79P0.21)3。X射线衍射结果表明,合成样品的结构为R3'c,对应的晶胞参数为a=b=0.663 8(1) nm,c=3.789 2(2) nm,V=1.446 15(6) nm3。在室温下,对样品进行原位高压X射线衍射研究,实验最高压力达到21.3 GPa,随着压力的升高,晶胞体积逐渐减小,但并没有观察到结构相变。利用Birch-Murnaghan状态方程对体积与压力的关系进行拟合,获得常温常压下的体积V0=1.441 4(24) nm3,体积模量K0=220(7) GPa。晶轴与压力的关系利用Murnaghan状态方程拟合,获得a轴和c轴的模量分别为Ka=257(9)和Kc=165(4),c轴较a轴容易压缩。  相似文献   
3.
β-MnO2高压相的从头计算模拟   总被引:1,自引:0,他引:1       下载免费PDF全文
 基于密度泛函理论(DFT),用完全势能线性缀加平面波方法(FPLAPW)计算模拟了MnO2的同质多相变体(金红石型结构、CaCl2型结构、黄铁矿型结构),通过计算,预测了β-MnO2在5 GPa时从金红石型结构转变为CaCl2型结构,在20 GPa时进一步转变为黄铁矿型结构。另外,还总结和比较了几种金红石型结构二氧化物的压致相变特点,得出第Ⅳ主族元素的金红石型结构氧化物有很好的规律性,发生的相变序列基本一致;并随着金属阳离子半径的增大,发生相变的压力值也相应地递减,各氧化物的体积模量值相应地减小。  相似文献   
4.
钙钛矿CaTiO3的超高压结构研究   总被引:4,自引:0,他引:4       下载免费PDF全文
巫翔  秦善  吴自玉  董宇辉  刘景  李晓东 《物理学报》2004,53(6):1967-1971
利用同步辐射x射线衍射和 DAC 高压技术在室温下测量了钙钛矿CaTiO3在压力0—44.53 GPa下的结构变化.结果表明,随着压力的增加CaTiO3的三个晶轴都受到不同程度的压缩,a,b的压缩率相近且相对比较大,c的压缩率最小,但没有证据表明有相变的发生.在压力范围内CaTiO3的P-V关系用Murnaghan状态方程表示,设定K′0=4,得到V0=0.2245(6)nm3和K0=222(9) GPa.应用赝立方角γpc与压力的关系,初 关键词: 3')" href="#">CaTiO3 结构 超高压 状态方程  相似文献   
5.
High pressure X-ray diffraction study of SrMnO3 perovskite   总被引:1,自引:0,他引:1  
Using a diamond anvil cell device and synchrotron radiation, the in-situ high-pressure structure of SrMnO3 has been investigated. At pressure up to 28.6 GPa, no pressure-induced phase transition is observed. The lattice parameters as a function of pressure is reported, and the relationship of the axial compression coefficients is βac. The isothermal bulk modulus K298=266(4) GPa is also obtained by fitting the pressure-volume data using the Murnaghan equation of state.  相似文献   
6.
Quasihydrostatic limit of LiF as a pressure transmitting medium is investigated by synchrotron radiation x-ray diffraction combined with the diamond anvil cells technique up to 60 GPa at room temperature. The equation-of- state parameters of LiF are determined to be Vo = 65.7(2)A3 Bo = 58(3) GPa and B'0 = 4.9(2) in the silicon oil environment; Vo = 67.4(3) A3, Bo = 51(3) GPa and B'0 = 4.7(2) without pressure transmitting medium. The full width at half maximum of LiF (111) peak increases with the increase of pressure in two independent experiments. The pressure distribution in the sample chamber is estimated by line-scanning x-ray diffraction measurements across the chamber's center, which presents as homogeneous with Pmax - Pmin Of about 1 GPa below 40 GPa.  相似文献   
7.
张倩  巫翔  秦善 《中国物理 B》2011,20(6):66101-066101
In situ high-pressure experiments of Co2P are carried out by means of angle dispersive X-ray diffraction with diamond anvil cell technique. No phase transition is observed in the present pressure range up to 15 GPa at room temperature, even at high temperature and 15 GPa. Results of compression for Co2P are well presented by the second-order Birch-Murnaghan equation of state with V0 = 130.99(2)3 (1=0.1 nm) and K0 = 160(3) GPa. Axial compressibilities are described by compressional modulus of the axis: Ka = 123(2) GPa, Kb = 167(8) GPa and Kc = 220(7) GPa. Theoretical calculations further support the experimental results and indicate that C23-type Co2P is stable at high pressure compared with the C22-type phase.  相似文献   
8.
High pressure X-ray diffraction study of CaMnO3 perovskite   总被引:1,自引:0,他引:1  
Using a diamond anvil cell device and synchrotron radiation,the in-situ high-pressure structure of CaMnO3 has been investigated.In the pressure up to 36.5 GPa,no pressure-induced phase transition is observed.The pressure dependence on the lattice parameters of CaMnO3 is reported,and the relationship of the axial compression coefficients is βa 〉 βc 〉 βb.The isothermal bulk modulus K298=224(25) GPa is also obtained by fitting the pressure-volume data using the Murnaghan equation of state.  相似文献   
9.
刘迎新  秦善  吴婧  李晓东  李延春  刘景 《中国物理 C》2009,33(11):1023-1027
The in-situ high-pressure structures of wulfenite have been investigated by means of angular dispersive X-ray diffraction with diamond anvil cell and synchrotron radiation. In the pressure up to 22.9 GPa, a pressure-induced scheelite-to-fergusonite transition is observed at about 10.6 GPa. The pressure dependence for the lattice parameters of wulfenite is reported, and the axial compression coefficients Ka0=-1.36×10-3 GPa-1 and Kc0= -2.78×10-3 GPa-1 are given. The room-temperature isothermal bulk modulus is also obtained by fitting the P-V data using the Murnaghan equation of state.  相似文献   
10.
利用金刚石压腔技术和原位同步辐射X射线衍射技术,对FeNiP(■)的压缩性进行了实验研究。常温下,FeNiP在0~23.4 GPa压力范围内保持■结构不变。用Birch-Murnaghan状态方程对单位晶胞体积随压力的变化关系(p-V关系)进行拟合,得到:体积模量K_0=153(2) GPa,体积模量微商K_0~′=5.7(2),零压下晶胞体积V_0=101.6(1)?~3;或K_0=167(1) GPa,K_0~′=4.0(固定值),V_0=101.5(1)?~3。与Fe_2P相比,FeNiP的体积模量更小,呈现出与Fe_2P相反、与Ni_2P相同的轴向压缩各向异性,据此探讨了Ni对(Fe,Ni)_2P压缩性的影响。应用当前实验结果,估算了FeNiP、Fe_2P、Fe_3P、Fe_(2.15)Ni_(0.85)P和Fe_3S在月球外核温压条件下的密度,通过与γ-Fe及月球外核密度的比较,得出Ni的加入会使"Fe-轻元素"体系的密度更接近月球外核密度,进一步阐释以多元合金体系(如Fe-Ni-S-P)为对象来研究行星核部物质组成更具合理性。  相似文献   
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