HIGH-PRESSURE STUDIES OF MAGNETITE AND MAGNESIOFERRITE USING SYNCHROTRON-RADIATION
HIGH-PRESSURE STUDIES OF MAGNETITE AND MAGNESIOFERRITE USING SYNCHROTRON-RADIATION
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DOI：
10.1016/0969-8043(95)00087-9
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发表时间：
1995-06-01
影响因子：
1.6
通讯作者：
OHEN, JS
中科院分区：
文献类型：
--
作者：
GERWARD, L;OHEN, JS
能量色散X射线衍射已成为高压工作的一项既定技术，特别是与金刚石顶锤高压室和同步辐射一起使用时。在本文中，我们将讨论这种方法的优点和局限性，并分别介绍在英国达累斯伯里实验室和法兰克福哈西拉布的同步辐射源上获得的一些结果。在正常条件下，Fe亚3 O亚4(磁铁矿)和镁铁亚2 O亚4(镁铁氧体)结晶为立方结构，空间群为Fd3m(No.227)。研究了这两种化合物在室温下50 Gpa(=500kbar)压力范围内的高压行为。通过将实验压力-体积数据与Birch状态方程进行拟合，确定了体积弹性系数Ksub0及其压力导数Ksub0sup‘。得到的参数分别为Ksub0=215(25)Gpa和Ksub0sup`=7.5(40)(Fe_2O_4)和K_sub0=233(40)Gpa和K_sub0_sup`=4.1(20)。磁铁矿在25 Gpa时转变为单斜结构。相变伴随着7%的体积收缩。在所研究的压力范围内，镁铁氧体没有发生相变。图2，参6。(作者)。
Energy dispersive x-ray diffraction has become an established technique for high-pressure work, particularly in conjunction with the diamond anvil high-pressure cell and synchrotron radiation. In this note we will discuss advantages and limitations of the method, and present some results obtained at the synchrotron radiation sources of Daresbury Laboratory, UK, and Hasylab, FRG, respectively. Under normal conditions Fe sub 3 O sub 4 (magnetite) and Mg Fe sub 2 O sub 4 (magnesioferrite) crystallize in a cubic structure with space group Fd3m (no. 227). The high-pressure behaviour of the two compounds has been studied in a pressure range up to 50 GPa (=500 Kbar) at room temperature. The bulk modulus, K sub 0, and its pressure derivative, K sub 0 sup `, have been determined by fitting the experimental pressure-volume data to the Birch equation of state. The resulting parameters are K sub 0 = 215 (25) GPa and K sub 0 sup ` = 7,5 (40) for Fe sub 3 O sub 4, and K sub 0 = 233 (40) GPa and K sub 0 sup ` = 4.1 (20) for Mg Fe sub 2 O sub 4. Magnetite transforms to a monoclinic structure at 25 GPa. The phase transition is accompanied by a 7% volume contraction. No phase transformation occurs for magnesioferrite in the pressure range investigated. 2 figs., 6 refs. (author).