Approach to rheology in the earth's crust based on the microstructure analysis

用矿物学和结晶学的方法，在显微结构分析的基础上，阐明了固态地壳的流变学。预计在高压和高温条件下，地壳中某些硅酸盐具有钙钛矿型结构。特别是固体的质子传导被认为在流变学中起着重要的作用，因为地球地壳中存在水。一些钙钛矿型烧结氧化物，如稀土元素掺杂的SrCeO_3、BaCeO_3和SrZrO_3在高温含氢气氛中表现出质子导电。掺Yb量为10%的掺Yb氧化物具有最高的质子电导率。以掺Yb量为5%和10%的氧化物为原料，采用固相反应法制备了掺Yb量为5%和10%的掺Yb氧化物粉末。对合成的材料进行了X射线粉末衍射、热重分析、差热分析和X射线吸收精细结构分析。10mol%的晶胞体积随温度的升高而单调增大，但在500~600℃之间有一个弯曲，比5mol%的约低300K。单位晶胞体积的这种弯曲被认为是由于氧气的损失，这与在相同温度范围内观察到的TGA的重量损失的结果是一致的。此外，在傅立叶合成中观察到氧离子的位移，随后在高温下氧的损失。综上所述，氧的行为在质子在固体中的传导机制中起着重要作用。

This work has been done to elucidate rheology of the solid state earth's crust based on the microstructure analysis by means of mineralogical and crystallographic approaches. It is expected that some silicates have perovskite-type structure under high pressure and at high temperature in the earth's crust. Especially proton conduction of solid is considered to play an important role in rheology because water is believed to exist in the earth's crust.Some perovskite-type sintered oxides such as lanthanide element-doped SrCeO_3, BaCeO_3 and SrZrO_3 show the proton conductivity in hydrogen-containing atmosphere at high temperature. The chemical stability of SrZrO_3-based oxide is much better and 10 mol % Yb-doped SrZrO_3 oxide shows the highest proton conductivity among SrZrO_3-substituted zirconium with lanthanide elements.The powder samples of 5 and 10 mol % Yb-doped SrZrO_3 oxides been synthesized by solid state reaction using the corresponding oxides as starting materials. The materials synthesized have been studied by X-ray powder diffraction, thermogravimetric analysis(TGA), differential thermal analysis and X-ray absorption fine structure spectroscopy. The orthorhombic unit cell volume of 10 mol % one increases monotonously with increasing temperature but exhibits a bent between 500℃ and 600 ℃ which is about 300K lower than that of 5 mol % one. This bent of the unit cell volume is considered to be due to a loss of oxygen, which is consistent with the result of a weight loss in TGA observed in the same temperature range. In addition the displacements of oxide ions were observed were observed in the Fourier syntheses followed by a loss of oxygen at high temperature.In conclusion the oxygen behavior plays an important role in the conduction mechanism of proton in solids.