no 18-presentation of working conference-ruilian tang 20150522

1、1Electrical resistance measurement of mineralsunder high pressure: water influence on electrical conductivityRuilian Tang唐瑞莲 MSC Lab HPSTARJiuhua ChenJan. 15th 20151Outline2I.BackgroundII.Experimental Devices and Measurement MethodsIII.Results of Goethite -FeOOHIV.Research PlanI. Background3I. Backg

2、round4I. Background3Hydrated metamorphic mineralsOH-Anhydrous silicate minerals (olivine, pyroxene etc.) and theirhigh-pressure structure phases (wadsleyite, ringwoodite, perovskite, etc.)OH-Water in the earths mantleOH- H+Dense hydrous magnesium silicateOH- H2OMelt silicate and carbonateI. Backgrou

3、nd3Water (as a source of hydrogen) is a minor phase but plays an important role in a number of processes in the mantle! How much water? Whole mantle convection or stratified convection?Distribution of water？Influence on electrical conductivity?Hydrated metamorphic mineralsOH-Anhydrous silicate miner

4、als (olivine, pyroxene etc.) and theirhigh-pressure structure phases (wadsleyite, ringwoodite, perovskite, etc.)OH-Water in the earths mantleOH- H+Dense hydrous magnesium silicateOH- H2OMelt silicate and carbonate Peacock, S. A., Science 1990, 248, 329-337. Bell, D. R.; Rossman, G. R., Science 1992,

5、 255, 1391-1397.I. Background4an effective methodThe components and changes of the earths interiorElectrical conductivity measurementI. Background4an effective methodThe components and changes of the earths interiorElectrical conductivity measurementvery small quantity of waterI. Background4an effec

6、tive methodThe components and changes of the earths interiorElectrical conductivity measurementSuch as : wadsleyite and ringwooditevery small quantity of waterThe estimated water content in the north Pacific transition zone ( 0.1 0.2 wt%) is significantly higher than the estimated water content in t

7、he upper mantle.a marked layering in water content in the earths mantle!Comparison of laboratory data on electrical conductivity as a function of water content with the geophysically inferred electrical conductivity in the mantle transition zone in the Pacific.Huang, X.; Xu, Y.; Karato, S.-i., Natur

8、e 2005, 434, 746-749.Utada, H.; Koyama, T.; Shimizu, H.; Chave, A., Geophysical research letters 2003, 30.I. Background5OlivineExplain the abnormal phenomenon of high conductivity on the top of asthenosphere.Comparison of the conductivity of hydrogen-bearing olivine with geophysically inferred elect

9、rical conductivity for the asthenosphere. Wang, D.; Mookherjee, M.; Xu, Y.; Karato, S., Nature 2006, 443, 977-80.II. Experimental Devices and Measurement Methods6u Hand-work four electrodes method(a)(b)(a) Schematic cross-section of the experimental set-up. (b) Schematic top view of the experimental

10、 set-up.II. Experimental Devices and Measurement Methods6u Hand-work four electrodes method(a)(b)(a) Schematic cross-section of the experimental set-up. (b) Schematic top view of the experimental set-up.Van de Pauw methodMeasurement methodAlternating Current (AC) Impedance Spectroscopy methodII. Exp

11、erimental Devices and Measurement Methods7u Van de Pauw methodBased on:A flat sample of arbitrary shape.The contacts are at the circumference of the sample and sufficiently small.The sample is homogeneous in thickness.The surface of the sample is singly connected.= VCD= VDAR, RAB,CDBC ,DAIIABBCo = p

12、 d RAB,CD + RBC,DARAB,CDfln 2 R2BC,DAd: thickness measurement of sample in the diamond anvil cell.f: a function of the ratio RAB,CD/RBC,DASchematic of Van de Pauw method d = TL ( P) - (H0 - Dp ) TL(P): thicknesses of loading.van der PAUYV, L., Philips Res. Rep. 1958, 13, 1-9.Li, M.; Gao, C.; Peng, G

13、.; Ma, Y.Z., Rev. Sci. Instrum.2007, 78, 075106.H : the height of the two anvils.0DP: the anvil deformation at everypressure.II. Experimental Devices and Measurement Methods8Electrical Resistivity Measurement of Magnetite Fe3O4 under High Pressure(a)(b)Electrical resistivity of Fe3O4 at high pressur

14、e. (a) data from Morris and Williams (1997); (b) This work.u The requirement of instrument:The resistance of mineral is generally very large. e.g. olivine (beyond our existing instruments range) need to purchase a instrument for higher resistance materials.III. Results of Goethite -FeOOH9III. Result

15、s of Goethite -FeOOH9ironIII. Results of Goethite -FeOOH9ironhydrous Fe-bearingmineralsIII. Results of Goethite -FeOOH9ironhydrous Fe-bearing mineralssimple hydroxidesquantifying more complex hydrogen-bearing compounds+III. Results of Goethite -FeOOH10(a)(b)Methanol : ethanol 4 : 1(a) Unit-cell volu

16、me as a function of pressure.(b) Peak widths (FWHM) normalized as a function of pressure. Nagai, T.; Kagi, H.; Yamanaka, T., American Mineralogist 2003, 88, 1423-1427.III. Results of Goethite -FeOOH11Energy as function of volume and enthalpy-pressure relation for thedifferent polymorphs within GGA a

17、nd GGA+U. Otte, K.; Pentcheva, R.; Schmahl, W. W.; Rustad, J. R., Physical Review B 2009, 80, 205116.-FeOOH6-7GPa- FeOOHPbnmP21mnIII. Results of Goethite -FeOOH12High Pressure Raman Spectra of Goethite -FeOOH(a)(b)(a) Selected Raman spectra of -FeOOH under high pressure.(b) Pressure dependences of R

18、aman shifts -FeOOH.III. Results of Goethite -FeOOH13Alternating Current Impedance Spectroscopy of Goethite -FeOOH under High PressuresThe Nyquist plots of impedance spectroscopy of goethite -FeOOH at high pressures.III. Results of Goethite -FeOOH13Alternating Current Impedance Spectroscopy of Goethi

19、te -FeOOH under High PressuresThe Nyquist plots of impedance spectroscopy of goethite -FeOOH at high pressures.III. Results of Goethite -FeOOH13Alternating Current Impedance Spectroscopy of Goethite -FeOOH under High PressuresThe Nyquist plots of impedance spectroscopy of goethite -FeOOH at high pre

20、ssures.III. Results of Goethite -FeOOH14(b)(a) Equivalent circuit used to represent the electrical properties of grain and grainboundary effects in -FeOOH at 6.6 GPa.(b) The fitting result of grain, grain boundary and total resistance of -FeOOH versus pressure.theRt = Rg + RgbIII. Results of Goethit

21、e -FeOOH14(b)(a) Equivalent circuit used to represent the electrical properties of grain and grainboundary effects in -FeOOH at 6.6 GPa.(b) The fitting result of grain, grain boundary and total resistance of -FeOOH versus pressure.theRt = Rg + RgbPressure transmitting medium: argon or neon. Research

22、 Plan15. Research Plan15Future research plan: 1.Synthesizehydrousmineralswithdifferentwater(hydrogen)content. e.g. ferropericlase, perovskite. Research Plan15Future research plan: 1.Synthesizehydrousmineralswithdifferentwater(hydrogen)content. e.g. ferropericlase, perovskite. 2. Investigate the wate

23、r influence on electrical conductivity of theseminerals under high pressures. Research Plan15Future research plan:1.Synthesizehydrousmineralswithdifferentwater(hydrogen)content. e.g. ferropericlase, perovskite.2. Investigate the water influence on electrical conductivity of these minerals under high

24、 pressures.I hope I can obtain some valuable data. It can explain some confusionsand debates. Let us know more about our earth.16Thank you for your attentions!The deformation of anvils as a function of pressure17Based on : completely plastic deformation on the gasket. completely elastic deformation of the diamonds.DP = H0 - TD (P) - Lm DP: the anvil deformation at every pressure.TD(P): thicknesses of unloading.H0: the height of the two anvils.Lm: the sample thickness at max