Abstract
Electrical resistivity of synthetic nanocrystalline (30-40 nm crystallite size) and a crystalline natural sample of geikielite MgTiO3 has been measured at simultaneous high pressure and high temperature up to 6 GPa and 800 K, respectively. The temperature dependence of the electrical resistivity of both the synthetic and natural sample obeys the Arrehenius behavior in the temperature range between 3 and 800 K and pressure range up to 6.0 GPa. The activation volume of the electrical conduction for coarse crystalline natural sample of geikielite is almost twice that of the synthetic nanocrystalline geikielite indicating the increase of activation volume with the crystallite size. The activation energy for the electronic conduction decreases from 0.39 eV at room pressure to 0.25 eV at 6.0 GPa for natural geikielite, and 0.68 to 0.225 eV in the same pressure range for synthetic geikielite. The pressure dependence of the activation energy of geikielite sample is found to obey the following expressions
ΔE (eV) = 0.39 - 0.026(1) P + 0.0036 P2 for natural sample, and
ΔE (eV) = 0.68 - 0.080 (2) P + 0.0007 P2 for synthetic sample,
where P is pressure in GPa. We observe a crossover from extended state type conduction to hopping conduction at 4.0 GPa and 350 K for nano-crystalline geikielite. However, there is no such change of conduction mechanism observed for the natural geikielite at high pressures and high temperatures. The present study reveals the phase stability of nano-crystalline geikielite and natural geikielite up to mantle pressure and temperature conditions, viz. 6 GPa and 800 K, and no phase transition or decomposition is observed in the sample.
© 2015 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- Comparative in situ X-ray diffraction study of San Carlos olivine: Influence of water on the 410 km seismic velocity jump in Earth’s mantle
- Visualizing trace element distribution in quartz using cathodoluminescence, electron microprobe, and laser ablation-inductively coupled plasma-mass spectrometry
- Krotite, CaAl2O4, a new refractory mineral from the NWA 1934 meteorite
- Translation interface modulation in NC-pyrrhotites: Direct imaging by TEM and a model toward understanding partially disordered structural states
- Crystal chemistry of Ti-rich fluorophlogopite from Presidente Olegario, Alto Paranaíba igneous province, Brazil
- First-principles study of diffusion and viscosity of anorthite (CaAl2Si2O8) liquid at high pressure
- Aluminous and alkali-deficient tourmaline from the Singhbhum Shear Zone, East Indian shield: Insight for polyphase boron infiltration during regional metamorphism
- Effect of lactate, glycine, and citrate on the kinetics of montmorillonite dissolution
- Acid neutralization by dissolution of alkaline paper mill wastes and implications for treatment of sulfide-mine drainage
- Fast ion conduction character and ionic phase-transition in silver sulfosalts: The case of fettelite [Ag6As2S7][Ag10HgAs2S8]
- Structure of walstromite, BaCa2Si3O9, and its relationship to CaSiO3-walstromite and wollastonite-II
- Cathodoluminescence properties and trace element signature of hydrothermal quartz: A fingerprint of growth dynamics
- Formation conditions for triple-chain silicates
- In situ determination of the spinel–post-spinel transition in Fe3O4 at high pressure and temperature by synchrotron X-ray diffraction
- PVT equation of state of epsilon iron and its densities at inner core conditions
- Pressure-induced structural phase transition of the iron end-member of ringwoodite (g-Fe2SiO4) investigated by X-ray diffraction and Mössbauer spectroscopy
- Non-bridging oxygen and high-coordinated aluminum in metaluminous and peraluminous calcium and potassium aluminosilicate glasses: High-resolution 17O and 27Al MAS NMR results
- The crystal structure of δ-Al(OH)3: Neutron diffraction measurements and ab initio calculations
- Electrical properties of natural and synthetic nano-crystalline MgTiO3 geikielite at mantle pressure and temperature conditions
- Density measurement of liquid FeS at high pressures using synchrotron X-ray absorption
- Cranswickite MgSO4·4H2O, a new mineral from Calingasta, Argentina
- Ambrinoite, (K,NH4)2(As,Sb)8S13·H2O, a new mineral from Upper Susa Valley, Piedmont, Italy: The first natural (K,NH4)-hydrated sulfosalt
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