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1

Formation and diffusion of vacancy-polaron complex in olivine-type LiMnPO4 and LiFePO4  

NASA Astrophysics Data System (ADS)

Formation and diffusion of a vacancy-polaron complex in olivine-type cathode-active materials, namely, LiMPO4 (M = Fe, Mn), were theoretically investigated by using the first-principles density functional theory within a framework of GGA + U method. It is shown that a lithium vacancy and a corresponding hole-polaron form the complex at the fully lithiated limit owing to lattice distortion and Coulomb interaction between them. It is also shown that the formation energy of the complex in LiMnPO4 is 0.19 eV higher than that in LiFePO4, since a hole polaron in LiMnPO4 is not sufficiently relaxed. As a result, the nucleation rate of MnPO4 phase in LiMnPO4 is 10-3 times slower than that in LiFePO4 and represents the main difference between the kinetics in the initial stage of charging of the two olivine materials. It was also found that the activation energy of the complex diffusion is limited by vacancy hopping in LiMnPO4, while it is determined by both vacancy hopping and polaron hopping in LiFePO4. The activation energy in LiMnPO4, 0.38 eV, is comparable with that in LiFePO4, 0.42 eV. The calculated potential energy profile, showed that the minimum energy path of the diffusing lithium in LiMnPO4 has the same winding shape as that in LiFePO4.

Asari, Yusuke; Suwa, Yuji; Hamada, Tomoyuki

2011-10-01

2

Comparison of small polaron migration and phase separation in olivine LiMnPO4 and LiFePO4 using hybrid density functional theory  

Microsoft Academic Search

Using hybrid density functional theory based on the Heyd-Scuseria-Ernzerhof (HSE06) functional, we compared polaron migration and phase separation in olivine LiMnPO4 to LiFePO4. The barriers for free hole and electron polaron migration in the Mn olivine system are calculated to be 303 and 196 meV, respectively, significantly higher than the corresponding barriers of 170 and 133 meV, respectively, for the

Shyue Ping Ong; Vincent L. Chevrier; Gerbrand Ceder

2011-01-01

3

Formation and diffusion of vacancy-polaron complex in olivine-type LiMnPO4 and LiFePO4  

Microsoft Academic Search

Formation and diffusion of a vacancy-polaron complex in olivine-type cathode-active materials, namely, LiMPO4 (M = Fe, Mn), were theoretically investigated by using the first-principles density functional theory within a framework of GGA + U method. It is shown that a lithium vacancy and a corresponding hole-polaron form the complex at the fully lithiated limit owing to lattice distortion and Coulomb

Yusuke Asari; Yuji Suwa; Tomoyuki Hamada

2011-01-01

4

A comparative study of magnetic properties of LiFePO4 and LiMnPO4  

Microsoft Academic Search

A detailed comparative study of the magnetic properties of LiFePO4 and LiMnPO4 samples is presented. Magnetic susceptibility, electron paramagnetic resonance and 7Li NMR experiments were performed on samples as prepared for electrochemical studies. The ground state of LiFePO4 seems to be that of a collinear antiferromagnet and very robust against crystal imperfections. On the other hand, our LiMnPO4 samples possess

Denis Arcon; Andrej Zorko; Robert Dominko; Zvonko Jaglicic

2004-01-01

5

A comparative study of magnetic properties of LiFePO4 and LiMnPO4  

NASA Astrophysics Data System (ADS)

A detailed comparative study of the magnetic properties of LiFePO4 and LiMnPO4 samples is presented. Magnetic susceptibility, electron paramagnetic resonance and 7Li NMR experiments were performed on samples as prepared for electrochemical studies. The ground state of LiFePO4 seems to be that of a collinear antiferromagnet and very robust against crystal imperfections. On the other hand, our LiMnPO4 samples possess a weak ferromagnetic ground state with a transition temperature TN = 42 K. We suggest that solitons may be very important magnetic excitations in these systems and that pinning of solitons below TN together with frustration plays a decisive role in the formation of the weak ferromagnetic state in LiMnPO4. The differences between the magnetic properties of these two samples reflect also the differences between their electronic structures and may thus be important for the electrochemistry of LiFePO4 and LiMnPO4.

Arcon, Denis; Zorko, Andrej; Dominko, Robert; Jaglicic, Zvonko

2004-08-01

6

Thermal instability of Olivine-type LiMnPO 4 cathodes  

Microsoft Academic Search

The remarkable thermal stability of LiFePO4 and its charged counterpart, FePO4, have been instrumental in its commercialization as a lithium-ion battery cathode material. Despite the similarity in composition and structure, and despite the high thermal stability of the parent compound, LiMnPO4, we find that the delithiated phase LiyMnPO4 (which contains a small amount of residual lithium), is relatively unstable and

Guoying Chen; Thomas J. Richardson

2010-01-01

7

Weak ferromagnetism of LiMnPO 4  

Microsoft Academic Search

Structural and magnetic properties of the novel materials for lithium batteries LiFePO4 and LiMnPO4 were studied by X-ray diffraction, SQUID magnetometry and EPR spectroscopy. LiMnPO4 has an olivine-type structure with a Mn-ion square lattice in the b–c plane. The occupation factors for Li and those oxygen atoms, which bridge Mn ions in the b–c plane showed noticeable deviation from the

D. Arcon; A. Zorko; P. Cevc; R. Dominko; M. Bele; J. Jamnik; Z. Jaglicic; I. Golosovsky

2004-01-01

8

Molecular wiring of LiMnPO 4 (olivine) by ruthenium(II)-bipyridine complexes  

Microsoft Academic Search

LiMnPO4 (olivine) was surface-modified by two different complexes: Ru-bis(4,4?-diethoxycarbonyl-2,2?-bipyridine)(4,4?-dicarboxylate-2,2?-bipyridine) and Ru-bis(4-carboxylic acid-4?-carboxylate-2,2?-bipyridine)(4,4?-dinonyl-2,2?bipyridine). These complexes have redox potentials of 4.45 and 4.25V vs. Li\\/Li+, respectively, and are both active for molecular wiring of LiMnPO4. The surface-confined Ru(II)\\/Ru(III) redox reaction propagates across the monolayer via hole-hopping, allowing a subsequent chemical delithiation of the underneath olivine towards MnPO4. The activity of LiMnPO4 is

Ladislav Kavan; Marketa Zukalova; Ivan Exnar; Shaik M. Zakeeruddin; Michael Graetzel

2009-01-01

9

Comparative studies of the electronic structure of LiFePO4, FePO4, Li3PO4, LiMnPO4, LiCoPO4, and LiNiPO4  

Microsoft Academic Search

We report a comparative study of the electronic structures of LiFePO4, FePO4, Li3PO4, LiMnPO4, LiCoPO4, and LiNiPO4. We used the spin-polarized ab initio orthogonalized linear combinations of atomic orbitals method for the calculation. Li3PO4 is a large-band gap insulator with a band gap of 5.75 eV. For other crystals containing the 3d-transition metals (TM), the localized 3d bands of the

Yong-Nian Xu; W. Y. Ching; Yet-Ming Chiang

2004-01-01

10

General synthesis and morphology control of LiMnPO 4 nanocrystals via microwave-hydrothermal route  

Microsoft Academic Search

Olivine structure LiMnPO4 has been considered as one of the very promising electrodes for lithium-ion batteries because of their low cost, low toxicity and high voltage plateau compared with LiFePO4. In order to improve the electrochemical performance a key challenge in the field of lithium-ion battery, is to explore and invent suitable synthetic route to control the size and morphology

Hongmei Ji; Gang Yang; Huan Ni; Soumyajit Roy; João Pinto; Xuefan Jiang

2011-01-01

11

Crystal structure and lithium electrochemical extraction properties of olivine type LiFePO 4  

Microsoft Academic Search

Lithium iron phosphate (LiFePO4) cathode material has been synthesized by a solid-state reaction. The XRD patterns and SEM images of the samples show that the LiFePO4 compounds prepared at 650°C by using carbon gel in reaction have a single-phase, small grain-size and regular shapes. By using Rietveld refinement method, we calculated the Li–O interatomic distance in LiO6 octahedra and the

Y. Z. Dong; Y. M. Zhao; H. Duan

2011-01-01

12

Olivine-type cathodes  

Microsoft Academic Search

The recent progress at Sony in the design of practical olivine-type cathodes is reviewed briefly. First principle calculations revealed LiFePO4 is a semiconductor with ca. 0.3eV band gap and LiMnPO4 is an insulator with ca. 2eV band gap, which seems the major intrinsic obstacle to a smooth redox reaction at 4V in the Mn-rich phase. Attention is also focused on

Atsuo Yamada; Mamoru Hosoya; Sai-Cheong Chung; Yoshihiro Kudo; Koichiro Hinokuma; Kuang-Yu Liu; Yoshio Nishi

2003-01-01

13

Comparison of electrochemical performances of olivine NaFePO4 in sodium-ion batteries and olivine LiFePO4 in lithium-ion batteries  

NASA Astrophysics Data System (ADS)

Carbon-coated olivine NaFePO4 (C-NaFePO4) spherical particles with a uniform diameter of ~80 nm are obtained by chemical delithiation and subsequent electrochemical sodiation of carbon-coated olivine LiFePO4 (C-LiFePO4), which is synthesized by a solvothermal method. The C-NaFePO4 electrodes are identical (particle size, particle size distribution, surface coating, and active material loading, etc.) to C-LiFePO4 except that Li ions in C-LiFePO4 are replaced by Na ions, making them ideal for comparison of thermodynamics and kinetics between C-NaFePO4 cathode in sodium-ion (Na-ion) batteries and C-LiFePO4 in lithium-ion (Li-ion) batteries. In this paper, the equilibrium potentials, reaction resistances, and diffusion coefficient of Na in C-NaFePO4 are systematically investigated by using the galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and compared to those of the well-known LiFePO4 cathodes in Li-ion batteries. Due to the lower diffusion coefficient of Na-ion and higher contact and charge transfer resistances in NaFePO4 cathodes, the rate performance of C-NaFePO4 in Na-ion batteries is much worse than that of C-LiFePO4 in Li-ion batteries. However, the cycling stability of C-NaFePO4 is almost comparable to C-LiFePO4 by retaining 90% of its capacity even after 100 charge-discharge cycles at a charge-discharge rate of 0.1 C.Carbon-coated olivine NaFePO4 (C-NaFePO4) spherical particles with a uniform diameter of ~80 nm are obtained by chemical delithiation and subsequent electrochemical sodiation of carbon-coated olivine LiFePO4 (C-LiFePO4), which is synthesized by a solvothermal method. The C-NaFePO4 electrodes are identical (particle size, particle size distribution, surface coating, and active material loading, etc.) to C-LiFePO4 except that Li ions in C-LiFePO4 are replaced by Na ions, making them ideal for comparison of thermodynamics and kinetics between C-NaFePO4 cathode in sodium-ion (Na-ion) batteries and C-LiFePO4 in lithium-ion (Li-ion) batteries. In this paper, the equilibrium potentials, reaction resistances, and diffusion coefficient of Na in C-NaFePO4 are systematically investigated by using the galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and compared to those of the well-known LiFePO4 cathodes in Li-ion batteries. Due to the lower diffusion coefficient of Na-ion and higher contact and charge transfer resistances in NaFePO4 cathodes, the rate performance of C-NaFePO4 in Na-ion batteries is much worse than that of C-LiFePO4 in Li-ion batteries. However, the cycling stability of C-NaFePO4 is almost comparable to C-LiFePO4 by retaining 90% of its capacity even after 100 charge-discharge cycles at a charge-discharge rate of 0.1 C. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr32758a

Zhu, Yujie; Xu, Yunhua; Liu, Yihang; Luo, Chao; Wang, Chunsheng

2012-12-01

14

Comparison of electrochemical performances of olivine NaFePO4 in sodium-ion batteries and olivine LiFePO4 in lithium-ion batteries.  

PubMed

Carbon-coated olivine NaFePO(4) (C-NaFePO(4)) spherical particles with a uniform diameter of ?80 nm are obtained by chemical delithiation and subsequent electrochemical sodiation of carbon-coated olivine LiFePO(4) (C-LiFePO(4)), which is synthesized by a solvothermal method. The C-NaFePO(4) electrodes are identical (particle size, particle size distribution, surface coating, and active material loading, etc.) to C-LiFePO(4) except that Li ions in C-LiFePO(4) are replaced by Na ions, making them ideal for comparison of thermodynamics and kinetics between C-NaFePO(4) cathode in sodium-ion (Na-ion) batteries and C-LiFePO(4) in lithium-ion (Li-ion) batteries. In this paper, the equilibrium potentials, reaction resistances, and diffusion coefficient of Na in C-NaFePO(4) are systematically investigated by using the galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and compared to those of the well-known LiFePO(4) cathodes in Li-ion batteries. Due to the lower diffusion coefficient of Na-ion and higher contact and charge transfer resistances in NaFePO(4) cathodes, the rate performance of C-NaFePO(4) in Na-ion batteries is much worse than that of C-LiFePO(4) in Li-ion batteries. However, the cycling stability of C-NaFePO(4) is almost comparable to C-LiFePO(4) by retaining 90% of its capacity even after 100 charge-discharge cycles at a charge-discharge rate of 0.1 C. PMID:23235803

Zhu, Yujie; Xu, Yunhua; Liu, Yihang; Luo, Chao; Wang, Chunsheng

2013-01-21

15

Rate-induced solubility and suppression of the first-order phase transition in olivine LiFePO4.  

PubMed

The impact of ultrahigh (dis)charge rates on the phase transition mechanism in LiFePO4 Li-ion electrodes is revealed by in situ synchrotron diffraction. At high rates the solubility limits in both phases increase dramatically, causing a fraction of the electrode to bypass the first-order phase transition. The small transforming fraction demonstrates that nucleation rates are consequently not limiting the transformation rate. In combination with the small fraction of the electrode that transforms at high rates, this indicates that higher performances may be achieved by further optimizing the ionic/electronic transport in LiFePO4 electrodes. PMID:24707878

Zhang, Xiaoyu; van Hulzen, Martijn; Singh, Deepak P; Brownrigg, Alex; Wright, Jonathan P; van Dijk, Niels H; Wagemaker, Marnix

2014-05-14

16

Emulsion drying synthesis of olivine LiFePO 4\\/C composite and its electrochemical properties as lithium intercalation material  

Microsoft Academic Search

The electroactive LiFePO4\\/C nano-composite has been synthesized by an emulsion drying method. During burning-out the oily emulsion precipitates in an air-limited atmosphere at 300°C, amorphous or low crystalline carbon was generated along with releasing carbon oxide gases, and trivalent iron as a cheap starting material was immediately reduced to the divalent one at this stage as confirmed by X-ray photoelectron

Seung-Taek Myung; Shinichi Komaba; Norimitsu Hirosaki; Hitoshi Yashiro; Naoaki Kumagai

2004-01-01

17

Electrical conductivity and reaction with lithium of LiFe 1? y Mn y PO 4 olivine-type cathode materials  

Microsoft Academic Search

Structural, electrical and electrochemical properties of Mn-substituted phospho-olivines LiFe1?yMnyPO4 were investigated and compared to those of LiFePO4. Rietvield refined XRD patterns taken in the course of delithiation process showed apparent difference between phase compositions of these cathode materials upon lithium extraction. Contrary to the LiFePO4 and LiMnPO4 compositions for which a two-phase mechanism of electrochemical lithium extraction\\/insertion is observed, in

J. Molenda; W. Ojczyk; J. Marzec

2007-01-01

18

Coupling of Li motion and structural distortions in olivine LiMnPO4 from 7Li and 31P NMR  

NASA Astrophysics Data System (ADS)

We present a detailed 7Li- and 31P-NMR study on single crystalline LiMnPO4 in the paramagnetic and antiferromagnetic phase (AFM, TN˜34 K). This allows us to determine the spin directions in the field-induced spin-flop phase. In addition, the anisotropic dipolar hyperfine coupling tensor of the 7Li and 31P nuclei is also fully determined by orientation and temperature-dependent NMR experiments and compared to the calculated values from crystal structure data. Deviations of the experimental values from the theoretical ones are discussed in terms of Mn disorder which is induced by Li disorder. In fact, the disorder in the Mn sublattice is directly revealed by diffuse x-ray scattering data. The present results provide experimental evidence for the Li diffusion strongly coupling to structural distortions within the MnPO4 host, which is expected to significantly affect the Li mobility as well as the performance of batteries based on this material.

Rudisch, Christian; Grafe, Hans-Joachim; Geck, Jochen; Partzsch, Sven; Zimmermann, M. v.; Wizent, Nadja; Klingeler, Rüdiger; Büchner, Bernd

2013-08-01

19

Multi-walled carbon nanotubes functionalized by carboxylic groups: Activation of TiO 2 (anatase) and phosphate olivines (LiMnPO 4; LiFePO 4) for electrochemical Li-storage  

Microsoft Academic Search

Multi-walled carbon nanotubes functionalized by carboxylic groups, exhibit better affinity towards TiO2 (P90, Degussa) as compared to that of pristine nanotubes. Also the electrochemical performance of TiO2 is improved by nanotube networking, but the Li-storage capacity of TiO2 is unchanged. Whereas the composite of TiO2 with non-functionalized nanotubes demonstrates simple superposition of the behavior of pure components, the composite with

Ladislav Kavan; Revathi Bacsa; Meltem Tunckol; Philippe Serp; Shaik M. Zakeeruddin; Florian Le Formal; Marketa Zukalova; Michael Graetzel

2010-01-01

20

Morphology regulation and carbon coating of LiMnPO 4 cathode material for enhanced electrochemical performance  

Microsoft Academic Search

Olivine-structured LiMnPO4 with uniform cluster-like and rod-like morphologies have been synthesized via a simple solvothermal process in water–organic solvent mixtures. The cluster-like LiMnPO4 microstructures are composed of numerous nanoplates in thickness of ca. 35nm and width of ca. 400nm. Carbon is coated on the LiMnPO4 surfaces by chemical vapor deposition (CVD) from methylbenzene and ball milling with acetylene black, respectively.

Fei Wang; Jun Yang; Pengfei Gao; Yanna NuLi; Jiulin Wang

2011-01-01

21

Thin film rechargeable electrodes based on conductive blends of nanostructured olivine LiFePO4 and sucrose derived nanocarbons for lithium ion batteries.  

PubMed

The present study provides the first reports of a novel approach of electrophoretic co-deposition technique by which titanium foils are coated with LiFePO4-carbon nanocomposites synthesized by sol gel route and processed into high-surface area cathodes for lithium ion batteries. The study elucidates how sucrose additions as carbon source can affect the surface morphology and the redox reaction behaviors underlying these cathodes and thereby enhance the battery performance. The phase and morphological analysis were done using XRD and XPS where the LiFePO4 formed was confirmed to be a high purity orthorhombic system. From the analysis of the relevant electrochemical parameters using cyclic voltammetry and electrochemical impedance spectroscopy, a 20% increment and 90% decrement in capacity and impedance values were observed respectively. The composite electrodes also exhibited a specific capacity of 130 mA h/g. It has been shown that cathodes based on such composite systems can allow significant room for improvement in the cycling performance at the electrode/electrolyte interface. PMID:23882803

Praveen, P; Jyothsna, U; Nair, Priya; Ravi, Soumya; Balakrishnan, A; Subramanian, K R V; Nair, A Sreekumaran; Nair, V Shantikumar; Sivakumar, N

2013-08-01

22

Enhanced electrochemical performance of unique morphological LiMnPO 4 \\/ C cathode material prepared by solvothermal method  

Microsoft Academic Search

The LiMnPO4\\/C composite material with ordered olivine structure was synthesized in 1:1(v\\/v) enthanol–water mixed solvent in the presence of cetyltrimethylammonium bromide (CTAB) at 240?C. Rod-like particle morphology of the resulting LiMnPO4\\/C powder with a uniform particle dimension of 150 × 600 nm was observed by using scanning electron microscope and the amount of carbon coated on the particle surface was evaluated as

Yourong Wang; Yifu Yang; Yanbo Yang; Huixia Shao

2010-01-01

23

Precursor-based synthesis and electrochemical performance of LiMnPO 4  

Microsoft Academic Search

Olivine-like LiMnPO4 was prepared from the NH4MnPO4·H2O precursor precipitated from the aqueous solution. Different morphologies of the LiMnPO4 were obtained by the solid-state reaction of the precursor with LiOH (granular, 100–300nm) and by ion-exchange reaction with eutectic mixture LiCl–LiNO3 (flake-like crystallites up to 10?m). The morphology and size distribution of the precursor NH4MnPO4·H2O is preserved during ion-exchange, establishing a new

Natalia N. Bramnik; Helmut Ehrenberg

2008-01-01

24

LiMnPO4 nanoplate grown via solid-state reaction in molten hydrocarbon for Li-ion battery cathode.  

PubMed

Electrochemically active LiMnPO(4) nanoplates have been synthesized via a novel, single-step, solid-state reaction in molten hydrocarbon. The olivine-structured LiMnPO(4) nanoplates with a thickness of approximately 50 nm appear porous and were formed as nanocrystals were assembled and grew into nanorods along the [010] direction in the (100) plane. After carbon coating, the prepared LiMnPO(4) cathode demonstrated a flat potential at 4.1 V versus Li with a specific capacity reaching as high as 168 mAh/g under a galvanostatic charging/discharging mode, along with an excellent cyclability. PMID:20698592

Choi, Daiwon; Wang, Donghai; Bae, In-Tae; Xiao, Jie; Nie, Zimin; Wang, Wei; Viswanathan, Vilayanur V; Lee, Yun Jung; Zhang, Ji-Guang; Graff, Gordon L; Yang, Zhenguo; Liu, Jun

2010-08-11

25

The preparation and characterization of olivine LiFePO 4\\/C doped with MoO 3 by a solution method  

Microsoft Academic Search

Composite Li0.99Mo0.01FePO4\\/C cathode materials were prepared by an easy solution method followed by heat-treating at various temperatures. XRD, SEM, TGA\\/DTA, EA, CV, XPS and charge–discharge cycles were used to evaluate the Li0.99Mo0.01FePO4\\/C composite powders. The results indicate that mix-doping method does not affect the olivine structure of the cathode but considerably improves its capacity delivery and cycle performance. Among the

Ming Zhang; Li-Fang Jiao; Hua-Tang Yuan; Yong-Mei Wang; Jian Guo; Ming Zhao; Wei Wang; Xing-Di Zhou

2006-01-01

26

Cathode performance of LiMnPO 4\\/C nanocomposites prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment  

Microsoft Academic Search

LiMnPO4\\/C nanocomposites could be prepared by a combination of spray pyrolysis and wet ball-milling followed by heat treatment in the range of spray pyrolysis temperature from 200 to 500°C. The ordered LiMnPO4 olivine structure without any impurity phase could be identified by X-ray diffraction analysis for all samples. It could be also confirmed from scanning electron microscopy and transmission electron

Izumi Taniguchi

2011-01-01

27

Improved electrochemical activity of LiMnPO 4 by high-energy ball-milling  

Microsoft Academic Search

Olivine lithium manganese phosphate (LiMnPO4) becomes research focus because of its high energy density and improved thermal stability. However, its application in lithium ion batteries suffers severely from poor electrochemical activity due to low conductivity and structural instability upon the charge and discharge process. By applying a high-energy ball-milling method we succeed in improving the capacity delivery and rate capability.

Jiangfeng Ni; Yoshiteru Kawabe; Masanori Morishita; Masaharu Watada; Tetsuo Sakai

2011-01-01

28

Improving electrochemical performance of LiMnPO 4 by Zn doping using a facile solid state method  

Microsoft Academic Search

Olivine structure LiMnPO4\\/C as cathode materials for Li-ion batteries were synthesized via a simple solidstate reaction. Improvement of the electrochemical\\u000a performance of LiMnPO4\\/C cathode material was realized significantly by the method of doping Zn. The obtained LiMn0.95Zn0.05PO4\\/C electrode material was studied by the measurements of X-ray diffraction pattern, scanning electronic microscopy, electrochemical\\u000a impedance spectroscopy and electrochemical performance. The results indicate

Yourong Wang; Yafang Chen; Siqing Cheng; Liangnian He

2011-01-01

29

Thermal stabilities of delithiated olivine MPO 4 (M = Fe, Mn) cathodes investigated using first principles calculations  

Microsoft Academic Search

We present an analysis of the thermal reduction of delithiated LiMnPO4 and LiFePO4 based on the quarternary phase diagrams as calculated from first principles. Our results confirm the recent experimental findings that MnPO4 decomposes at a much lower temperature than FePO4, thereby potentially posing larger safety issues for LiMnPO4 cathodes. We find that while substantial oxygen is released as MnPO4

Shyue Ping Ong; Anubhav Jain; Geoffroy Hautier; Byoungwoo Kang; Gerbrand Ceder

2010-01-01

30

Tunable Morphology Synthesis of LiFePO4 Nanoparticles as Cathode Materials for Lithium Ion Batteries.  

PubMed

Olivine LiFePO4 with nanoplate, rectangular prism nanorod and hexagonal prism nanorod morphologies with a short b-axis were successfully synthesized by a solvothermal in glycerol and water system. The influences of solvent composition on the morphological transformation and electrochemical performances of olivine LiFePO4 are systematically investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and galvanostatic charge-discharge tests. It is found that with increasing water content in solvent, the LiFePO4 nanoplates gradually transform into hexagonal prism nanorods that are similar to the thermodynamic equilibrium shape of the LiFePO4 crystal. This indicates that water plays an important role in the morphology transformation of the olivine LiFePO4. The electrochemical performances vary significantly with the particle morphology. The LiFePO4 rectangular prism nanorods (formed in a glycerol-to-water ratio of 1:1) exhibit superior electrochemical properties compared with the other morphological particles because of their moderate size and shorter Li(+) ion diffusion length along the [010] direction. The initial discharge capacity of the LiFePO4@C with a rectangular prism nanorod morphology reaches to 163.8 mAh g(-1) at 0.2 C and over 75 mAh g(-1) at the high discharging rate of 20 C, maintaining good stability at each discharging rate. PMID:24892948

Ma, Zhipeng; Shao, Guangjie; Fan, Yuqian; Wang, Guiling; Song, Jianjun; Liu, Tingting

2014-06-25

31

Synthesis and characterization of LiFePO4 electrode materials coated by graphene  

NASA Astrophysics Data System (ADS)

Olivine-type LiFePO4/graphene composite materials were synthesized via a high temperature solid-state method. In this paper, the sintering process of LiFePO4 precursor was conducted simultaneously with the reduction of graphene oxide, and then LiFePO4 with a thin and homogeneous graphene-shell coating can be obtained. The effects of different graphene coating amount on the structure and electrochemical properties of LiFePO4 cathode were investigated. Test results indicated that LiFePO4 material modified with high electrical conductive graphene exhibited a morphology of uniform and fine spherical particles with high crystallinity. LiFePO4/graphene (92:8 wt.) cathode had the lowest charge transfer resistance among all tested samples. It delivered a capacity of 167 mAh g-1 at 0.1 C and could tolerate various discharge currents with a capacity decay rate of only 27.2% after cycled stepwise under 0.1 C, 2 C, 5 C for 15 times, respectively.

Tian, Zhe; Liu, Shanshan; Ye, Feng; Yao, Sijia; Zhou, Zhufa; Wang, Shumei

2014-06-01

32

Electrochemical properties of LiFePO 4 \\/C synthesized by mechanical activation using sucrose as carbon source  

Microsoft Academic Search

Olivine lithium iron phosphate (LiFePO4) is attracting much attention as a safe, low cost and high capacity cathode material for lithium batteries, especially for\\u000a applications in electric and hybrid-electric vehicles. In the present work, carbon-coated LiFePO4 (LiFePO4\\/C) materials are synthesized from lithium carbonate, ferrous oxalate, ammonium dihydrogen phosphate, and sucrose (varying\\u000a content) as starting materials, by the process of mechanical

Jae-Kwang Kim; Gouri Cheruvally; Jou-Hyeon Ahn

2008-01-01

33

Olivine-type nanosheets for lithium ion battery cathodes.  

PubMed

Olivine-type LiMPO4 (M = Fe, Mn, Co, Ni) has become of great interest as cathodes for next-generation high-power lithium-ion batteries. Nevertheless, this family of compounds suffers from poor electronic conductivities and sluggish lithium diffusion in the [010] direction. Here, we develop a liquid-phase exfoliation approach combined with a solvothermal lithiation process in high-pressure high-temperature (HPHT) supercritical fluids for the fabrication of ultrathin LiMPO4 nanosheets (thickness: 3.7-4.6 nm) with exposed (010) surface facets. Importantly, the HPHT solvothermal lithiation could produce monodisperse nanosheets while the traditional high-temperature calcination, which is necessary for cathode materials based on high-quality crystals, leads the formation of large grains and aggregation of the nanosheets. The as-synthesized nanosheets have features of high contact area with the electrolyte and fast lithium transport (time diffusion constant in at the microsecond level). The estimated diffusion time for Li(+) to diffuse over a [010]-thickness of <5 nm (L) was calculated to be less than 25, 2.5, and 250 ?s for LiFePO4, LiMnPO4, and LiCoPO4 nanosheets, respectively, via the equation of t = L(2)/D. These values are about 5 orders of magnitude lower than the corresponding bulk materials. This results in high energy densities and excellent rate capabilities (e.g., 18 kW kg(-1) and 90 Wh kg(-1) at a 80 C rate for LiFePO4 nanosheets). PMID:23713414

Rui, Xianhong; Zhao, Xiaoxu; Lu, Ziyang; Tan, Huiteng; Sim, Daohao; Hng, Huey Hoon; Yazami, Rachid; Lim, Tuti Mariana; Yan, Qingyu

2013-06-25

34

Electrochemical performance of LiFePO 4 thin films with different morphology and crystallinity  

Microsoft Academic Search

LiFePO4 thin films have been prepared by pulsed laser deposition method on titanium substrates. The influence of the deposition parameters, e.g. substrate temperature, ambient argon pressure, and post-annealing on the crystallinity and morphology of as-deposited thin films are investigated. Well-crystallized pure olivine-phase is obtained under optimized deposition condition (20–30Pa, 500°C). It shows a high electrochemical activity (83% theoretical capacity) at

Kun Tang; Jinpeng Sun; Xiqian Yu; Hong Li; Xuejie Huang

2009-01-01

35

LiFePO 4\\/carbon cathode materials prepared by ultrasonic spray pyrolysis  

Microsoft Academic Search

Small crystallites LiFePO4 powder with conducting carbon coating can be synthesized by ultrasonic spray pyrolysis. Cheaper trivalent iron ion is used as the precursor. The pure olivine phase can be prepared with the duplex process of spray pyrolysis (synthesized at 450, 550 or 650°C) and subsequent heat-treatment (at 650°C for 4h). The results indicate that the pyrolysis temperature of 450°C

Mu-Rong Yang; Tsung-Hsien Teng; She-Hung Wu

2006-01-01

36

Electronic Properties of LiFePO4 and Li doped LiFePO4  

SciTech Connect

The potential use of different iron phosphates as cathodematerials in lithium-ion batteries has recently been investigated.1 Oneof the promising candidates is LiFePO4. This compound has severaladvantages in comparison to the state-of-the-art cathode material incommercial rechargeable lithium batteries. Firstly, it has a hightheoretical capacity (170 mAh/g). Secondly, it occurs as mineraltriphylite in nature and is inexpensive, thermally stable, non-toxic andnon-hygroscopic. However, its low electronic conductivity (~;10-9 S/cm)results in low power capability. There has been intense worldwideresearch activity to find methods to increase the electronic conductivityof LiFePO4, including supervalent ion doping,2 introducingnon-carbonaceous network conduction3 and carbon coating, and theoptimization of the carbon coating on LiFePO4 particle surfaces.4Recently, the Li doped LiFePO4 (Li1+xFe1-xPO4) synthesized at ARL hasyield electronic conductivity increase up to 106.5 We studied electronicstructure of LiFePO4 and Li doped LiFePO4 by synchrotron based soft X-rayemission (XES) and X-ray absorption (XAS) spectroscopies. XAS probes theunoccupied partial density of states, while XES the occupied partialdensity of states. By combining XAS and XES measurements, we obtainedinformation on band gap and orbital character of both LiFePO4 and Lidoped LiFePO4. The occupied and unoccupied oxygen partial density ofstates (DOS) of LiFePO4 and 5 percent Li doped LiFePO4 are presented inFig. 1. Our experimental results clearly indicate that LiFePO4 has wideband gap (~; 4 eV). This value is much larger than what is predicted byDFT calculation. For 5 percent Li doped LiFePO4, a new doping state wascreated closer to the Fermi level, imparting p-type conductivity,consistent with thermopower measurement. Such observation substantiatesthe suggestion that high electronic conductivity in Li1.05Fe0.95 PO4 isdue to available number of charge carriers in the material. Furthermore,Hall effect measurement on Li doped sample confirmed presence of freecharge carriers, which are responsible for the observed electronicconductivity increase in Li doped LiFePO4. There is no evidence that Fe3+valence is created by doping with excessive Li+ in Li1.05Fe0.95PO4, asshown by Fe-edge XAS. (Fig.2) Instead, charge-carrier holes resideprimarily in unoccupied O 2p states, which compensate for the chargedeficiency from Li+ substitution for Fe2+. The increased conductivity inLi1.05Fe0.95PO4 is attributed to the new charge carriers (doped holes)and the strong electron correlation between O 2p and Fe 3dstates.

Zhuang, G.V.; Allen, J.L.; Ross, P.N.; Guo, J.-H.; Jow, T.R.

2005-06-28

37

Self-assembled LiFePO4 nanowires with high rate capability for Li-ion batteries.  

PubMed

Controlling the dimensions in the nanometer scale of olivine-type LiFePO4 has been regarded as one of the most effective strategies to improve its electrochemical performance for Li-ion batteries. In this communication, we demonstrate a novel LiFePO4 nanoarchitecture, which is composed of self-assembled single-crystalline nanowires and exhibits good rate capability with a reversible capacity of ?110 mA h g(-1) at a current rate of 30 C, and a stable capacity retention of ?86% after 1000 cycles at a current rate of 10 C. PMID:25011485

Peng, Lele; Zhao, Yu; Ding, Yu; Yu, Guihua

2014-07-24

38

First-Principles Investigation of Li Intercalation Kinetics in Phospho-Olivines  

NASA Astrophysics Data System (ADS)

This thesis focuses broadly on characterizing and understanding the Li intercalation mechanism in phospho-olivines, namely LiFePO 4 and Li(Fe,Mn)PO4, using first-principles calculations. Currently Li-ion battery technology is critically relied upon for the operation of electrified vehicles, but further improvements mainly in cathode performance are required to ensure widespread adoption, which in itself requires learning from existing commercial cathode chemistries. LiFePO4 is presently used in commercial Li-ion batteries, known for its rapid charge and discharge capability but with underwhelming energy density. This motivates the three central research efforts presented herein. First, we investigate the modified phase diagram and electrochemical properties of mixed olivines, such as Li(Fe,Mn)PO4, which offer improved theoretical energy density over LiFePO4 (due to the higher redox voltage associated with Mn2+/Mn3+). The Lix(Fe1-yMny)PO4 phase diagram is constructed by Monte Carlo simulation on a cluster expansion Hamiltonian parametrized by first-principles determined energies. Deviations from the equilibrium phase behavior and voltages of pure LiFePO4 and LiMnPO 4 are analyzed and discussed to good agreement with experimental observations. Second, we address why LiFePO4 exhibits superior rate performance strictly when the active particle size is brought down to the nano-scale. By considering the presence of immobile point defects residing in the 1D Li diffusion path, specifically by calculating from first principles both defect formation energies and Li migration barriers in the vicinity of likely defects, the Li diffusivity is recalculated and is found to strongly vary with particle size. At small particle sizes, the contribution from defects is small, and fast 1D Li diffusion is accessible. However, at larger particle sizes (microm scale and above) the contribution from defects is much larger. Not only is Li transport impeded, but it is also less anisotropic in agreement with experiments on large LiFePO4 single crystals. Third, we investigate why LiFePO4 can be charged and discharged rapidly despite having to undergo a first-order phase transition. Conventional wisdom dictates that a system with strong equilibrium Li segregation behavior requires both nucleation and growth in the charge and discharge process, which should impede the overall kinetics. Rather, through first-principles calculations, we determine the minimal energy required to access a non-equilibrium transformation path entirely through the solid solution. Not only does this transformation mechanism require little driving force, but it also rationalizes how a kinetically favorable but nonequilibrium path is responsible for the extremely high rate performance associated with this material. The consequences of a rapid non-equilibrium single-particle transformation mechanism on (dis)charging a multi-particle assembly, as is the case in porous electrodes, are discussed and compared to experimental observations. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

Malik, Rahul

39

First-principles studies of Mg-doped LiFePO4 for lithium ion batteries  

NASA Astrophysics Data System (ADS)

We investigate the formation energy, crystal parameters and electronic properties of Mg-doped (Li site and Fe site) lithium iron orthophosphate (LiFePO4) by using the first-principles calculations. We noticed that the Mg ions are much more easier to be doped on Fe site than Li site. Comparing with the pure LiFePO4, we found the band gap of Mg-doped LiFePO4 is a little narrower than that of the pure one, indicating that the enhancement of the electronic conductivity upon doping is likely. Furthermore, we discovered that Mg doped on the Fe site causes the bond length to change, which is consistent with our experimental data. The reduction of the Mg-O bond length favors the formation of Li^+ diffusion channels, hence improves the ionic dynamic properties of the olivine LiFePO4. Mg-doped LiFePO4 has bigger electricity peak area that the pure one, which is an indication of improved ionic diffusion.

Shi, Siqi; Zhang, Hua; Mei, Wai-Ning; Liu, Aifang; Lim, Khoon-Cheng

2010-03-01

40

Facile low-temperature polyol process for LiFePO4 nanoplate and carbon nanotube composite  

NASA Astrophysics Data System (ADS)

Crystalline LiFePO4 nanoplates were incorporated with 5 wt.% multi-walled carbon nanotubes (CNTs) via a facile low temperature polyol process, in one single step without any post heat treatment. The CNTs were embedded into the LiFePO4 particles to form a network to enhance the electrochemical performance of LiFePO4 electrode for lithium-ion battery applications. The structural and morphological characters of the LiFePO4-CNT composites were investigated by X-ray diffraction, Fourier Transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The electrochemical properties were analyzed by cyclic voltammetry, electrochemical impedance spectroscopy and charge/discharge tests. Primary results showed that well crystallized olivine-type structure without any impurity phases was developed, and the LiFePO4-CNT composites exhibited good electrochemical performance, with a reversible specific capacity of 155 mAh g-1 at the current rate of 10 mA g-1, and a capacity retention ratio close to 100% after 100 cycles.

Wu, Guan; Zhou, Yingke; Gao, Xuefeng; Shao, Zongping

2013-10-01

41

Carbonate anions controlled morphological evolution of LiMnPO4 crystals.  

PubMed

LiMnPO4 with a morphology controlled by carbonate anions was prepared via a simple template-free hydrothermal reaction; the LiMnPO4 shows a promising electrochemical activity as cathode material for lithium ion batteries. PMID:18292909

Fang, Haisheng; Li, Liping; Yang, Yong; Yan, Guofeng; Li, Guangshe

2008-03-01

42

Temperature Dependence of Aliovalent-vanadium Doping in LiFePO4 Cathodes  

SciTech Connect

Vanadium-doped olivine LiFePO4 cathode materials have been synthesized by a novel low-temperature microwave-assisted solvothermal (MW-ST) method at 300 oC. Based on chemical and powder neutron/X-ray diffraction analysis, the compositions of the synthesized materials were found to be LiFe1-3x/2Vx x/2PO4 (0 x 0.2) with the presence of a small number of lithium vacancies charge-compensated by V4+, not Fe3+, leading to an average oxidation state of ~ 3.2+ for vanadium. Heating the pristine 15 % V-doped sample in inert or reducing atmospheres led to a loss of vanadium from the olivine lattice with the concomitant formation of a Li3V2(PO4)3 impurity phase; after phase segregation, a partially V-doped olivine phase remained. For comparison, V-doped samples were also synthesized by conventional ball milling and heating, but only ~ 10 % V could be accommodated in the olivine lattice in agreement with previous studies. The higher degree of doping realized with the MW-ST samples demonstrates the temperature dependence of the aliovalent-vanadium doping in LiFePO4.

Harrison, Katharine L [University of Texas at Austin; Bridges, Craig A [ORNL; Paranthaman, Mariappan Parans [ORNL; Idrobo Tapia, Juan C [ORNL; Manthiram, Arumugam [University of Texas at Austin; Goodenough, J. B. [University of Texas at Austin; Segre, C [Illinois Institute of Technology; Katsoudas, John [Illinois Institute of Technology; Maroni, V. A. [Argonne National Laboratory (ANL)

2013-01-01

43

Characterization of the carbon coating onto LiFePO4 particles used in lithium batteries  

NASA Astrophysics Data System (ADS)

While nanosized ferromagnetic particles could poison the performance of the Li batteries containing phospho-olivine, the carbon-film coating the LiFePO4 particles has a beneficial effect on cycling life of the cells. In this paper, we present the properties of the carbon layer deposited at the surface of the LiFePO4 grains. Characteristics of the carbon layer are analyzed using scanning electron microscopy, high-resolution transmission scanning electron microscopy, Fourier transform infrared, and Raman scattering (RS) spectroscopy. The carbon deposit characterized by RS spectroscopy is hydrogenated with very small hydrogen/carbon ratio, so that it belongs to the family of the amorphous graphitic carbon. The carbon deposit is similar to that obtained by pyrolysis technique at high temperature. It is expected to have the same properties (small hardness, high electronic conductivity) that favor both the Li diffusion from the LiFePO4 bulk and the charge-discharge rate of the cell. A model for the Li-ion transport throughout the coating is given.

Julien, C. M.; Zaghib, K.; Mauger, A.; Massot, M.; Ait-Salah, A.; Selmane, M.; Gendron, F.

2006-09-01

44

Magnetic phase diagram of magnetoelectric LiMnPO4  

NASA Astrophysics Data System (ADS)

The nature of the spin-flop (SF) transition in the magnetoelectric quasi-2D Heisenberg system LiMnPO4 is studied in fields applied along the a axis. A refinement of the magnetic structure using neutron diffraction data in the SF phase reveals that the spins reorient from being parallel to the a axis to be nearly along the c axis at magnetic fields between 4 and 4.7 T, depending on temperature. The low-field antiferromagnetic phase boundary is shown to join the spin-flop line tangentially at the so-called bicritical point, where there is a suppression of the ordering temperature. At the bicritical field, we observe an increased intensity of the Lorentz broadened elastic scattering at magnetic Bragg peaks above TN as compared to zero field and 10 T, without an increase in peak width. This suggests an increased density of fluctuations at the bicritical field as compared to zero field.

Toft-Petersen, Rasmus; Andersen, Niels H.; Li, Haifeng; Li, Jiying; Tian, Wei; Bud'ko, Sergey L.; Jensen, Thomas B. S.; Niedermayer, Christof; Laver, Mark; Zaharko, Oksana; Lynn, Jeffrey W.; Vaknin, David

2012-06-01

45

Synthesis of LiyMnSiOx and LiMnPO4 nanostructures  

Microsoft Academic Search

Nanosized LiyMnSiOx and LiMnPO4 have been synthesized by a hydrothermal route. Simply by changing parameters such as metal precursors and\\/or template, high surface area LiyMnSiOx with different morphology and sizes were prepared, in particular hollow spheres and plate-like nanoparticles, however with poorly developed crystallinity. In the case of LiMnPO4, highly crystalline nanocrystals were prepared.Nanosized LiyMnSiOx and LiMnPO4 have been synthesized

Bettina Milke; Peter Strauch; Markus Antonietti; Cristina Giordano

2009-01-01

46

Preparation of carbon coated LiMnPO 4 powders by a combination of spray pyrolysis with dry ball-milling followed by heat treatment  

Microsoft Academic Search

Nanostructured LiMnPO4 particles could be successfully synthesized by an ultrasonic spray pyrolysis method from the precursor solution; LiNO3, Mn(NO3)2·6H2O and H3PO4 were stoichiometrically dissolved into distilled water. The X-ray diffraction analysis showed that the as-prepared powders which had the desired olivine structure without any impurity phase could be obtained in the reactor temperatures ranging from 500 to 800°C. Carbon coated

Zhumabay Bakenov; Izumi Taniguchi

2010-01-01

47

Raman measurements of temperature dependencies of phonons in LiMnPO 4  

Microsoft Academic Search

We present results of Raman and infrared absorption spectroscopy research on phonons in LiMnPO4—a new material for high capacitance rechargeable lithium-ion batteries. There is a significant interest in the structural and electrical properties of this material, because the battery performance depends strongly on the rate of lithium diffusion. Nanopowder of LiMnPO4 was obtained via a modified sol–gel method from salts

Krzysztof P. Korona; Joanna Papierska; Maria Kami?ska; Andrzej Witowski; Monika Michalska; Ludwika Lipi?ska

2011-01-01

48

Synthesis of LiyMnSiOx and LiMnPO4 nanostructures.  

PubMed

Nanosized Li(y)MnSiO(x) and LiMnPO(4) have been synthesized by a hydrothermal route. Simply by changing parameters such as metal precursors and/or template, high surface area Li(y)MnSiO(x) with different morphology and sizes were prepared, in particular hollow spheres and plate-like nanoparticles, however with poorly developed crystallinity. In the case of LiMnPO(4), highly crystalline nanocrystals were prepared. PMID:20644867

Milke, Bettina; Strauch, Peter; Antonietti, Markus; Giordano, Cristina

2009-10-01

49

Nanocrystalline LiMnPO 4 prepared by a new phosphate–formate precursor method  

Microsoft Academic Search

The preparation of homogeneous phosphate–formate precursors by freeze-drying of solutions containing lithium, Mn(II), phosphate and formate ions ensures production of stoichiometric, well crystallized, defectless and nano-sized LiMnPO4 powders at temperatures above 400°C. A systematic study of the influence of the synthesis conditions on the structure and morphology of LiMnPO4 is performed. It is established that the concentration of the solutions

V. Koleva; R. Stoyanova; E. Zhecheva

2010-01-01

50

Spin Dynamics and Spin-flop transition in Magnetoelectric Effect LiMnPO4  

Microsoft Academic Search

Neutron scattering techniques were used to study the magnetic phase transition and spin dynamics in single crystal LiMnPO4 both with and without magnetic field. Elastic scattering confirmed that LiMnPO4 has a collinear antiferromagnetic ground state with moments along a-axis in zero-field. The temperature dependent order parameter, calculated from the integrated intensity of the (010) magnetic reflection, was fit to a

J. Li; W. Tian; Y. Chen; J. L. Zarestky; D. Vaknin; J. W. Lynn

2008-01-01

51

Electrochemical lithiation and delithiation of LiMnPO 4: Effect of cation substitution  

Microsoft Academic Search

The electrochemical lithiation–delithiation reaction was examined for LiMnPO4 in which different cations were substituted for part of Mn. The X-ray diffraction analysis indicated that LiMnPO4 is tolerant, to some extent, to substitution of Mg2+, Ca2+ and Zr4+. The substitution of Mg2+ and\\/or Zr4+ led to an increased reversible capacity and a reduced polarization, whereas Ca2+ substitution had a detrimental effect

Jong-Won Lee; Min-Sik Park; Benayad Anass; Jin-Hwan Park; Meen-Seon Paik; Seok-Gwang Doo

2010-01-01

52

Magnetic Phase Transition and Spin Dynamics in Magnetoelectric Effect LiMnPO4  

Microsoft Academic Search

Elastic and inelastic neutron scattering techniques were used to study the magnetic phase transition and spin dynamics in single crystal LiMnPO4. In this mulitiferroic, antiferromagnetism coexists with induced ferroelectricity below the Neel temperature. Elastic neutron scattering technique confirmed that LiMnPO4 has a collinear antiferromagnetic ground state with magnetic moments oriented along the a-axis. The temperature dependent order parameter, calculated from

J. Li; W. Tain; J. L. Zarestky; D. Vaknin; Y. Chen; J. W. Lynn

2007-01-01

53

Synthesis of spherical LiMnPO 4\\/C composite microparticles  

Microsoft Academic Search

Spherical LiMnPO4\\/C composite microparticles were prepared by a combination of spray pyrolysis and spray drying followed by heat treatment and examined as a cathode material for lithium batteries. The structure, morphology and electrochemical performance of the resulting spherical LiMnPO4\\/C microparticles were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electronic microscopy and standard electrochemical techniques. The final sample was

Zhumabay Bakenov; Izumi Taniguchi

2011-01-01

54

The possibility of manganese disorder in LiMnPO 4 and its effect on the electrochemical activity  

Microsoft Academic Search

Orthorhombic structured LiMnPO4 was synthesized by a hydrothermal method. The possibility of manganese disorder in LiMnPO4 was studied using powder X-ray diffraction and X-ray absorption fine structure analysis. A manganese-rich model was proposed for the hydrothermally synthesized LiMnPO4. It is found that the extent of Mn2+ disorder on the Li+ sites was suppressed by increasing the reaction temperature, which led

Haisheng Fang; Zhiyun Pan; Liping Li; Yong Yang; Guofeng Yan; Guangshe Li; Shiqiang Wei

2008-01-01

55

Carbon coating by high-energy milling and electrochemical properties of LiMnPO 4 obtained in polyol process  

Microsoft Academic Search

LiMnPO4 materials were synthesized via a polyol process and coated with conductive carbon black by using high-energy milling. We introduced two kind of synthesis process of LiMnPO4\\/C according to carbon addition steps, which was carried out during high-energy milling or polyol process. The carbon addition during the polyol process followed by high-energy milling enabled carbon to be network with LiMnPO4

San Moon; P. Muralidharan; Do Kyung Kim

56

Fabrication of microspherical LiMnPO 4 cathode material by a facile one-step solvothermal process  

Microsoft Academic Search

The microspherical LiMnPO4 cathode material was successfully prepared for the first time by a simple one-step solvothermal process in the presence of critic acid. The reaction conditions (reactant concentration, reaction temperature) were used further to fabricate the size, surface coarseness and morphology of the microspherical LiMnPO4. The as-prepared microspherical LiMnPO4 at variant conditions exhibited remarkably different discharge capacity and rate

Yourong Wang; Yifu Yang; Yanbo Yang; Huixia Shao

2009-01-01

57

Electrochemical studies of molybdate-doped LiFePO4 as a cathode material in Li-ion batteries.  

PubMed

The use of molybdate as a new anionic dopant that replaces phosphate in LiFePO4 was studied. When a small amount of molybdate (0.5 mol%) was used as a dopant, the olivine structure was maintained, while the lattice volume increased by 0.4%. The expanded volume facilitates ionic transfer, because of which the capacity of doped LiFePO4 at high current discharge rates is higher than that of pure LiFePO4. The discharge value increased by 25.2% at a charge rate of 5 C when the material was doped with 0.5 mol% molybdate ions. The slight expansion of the lattice volume in the olivine structure facilitates a fast redox reaction by lowering the charge transfer resistance. The current values from cyclic voltammetry indicate that the oxidation (charge) process of the cathode material is more improved than the corresponding reduction (discharge) process. Increasing the level of doping beyond 0.5 mol% had no effect on the results. At some discharge rates, the discharge capacity became worse. Because molybdate is divalent while phosphate is trivalent, a large number of molybdate ions in the lattice can exert considerable stress on the structure. PMID:23858863

Kim, Ketack; Kam, Daewoong; Kim, Yeonjoo; Kim, Sinwoong; Kim, Minsoo; Kim, Hyun-Soo

2013-05-01

58

Synthesis of LiMnPO4 porous plates in mixed solvents system.  

PubMed

0.6 to 7.5 microm LiMnPO4 porous plates with pore sizes from 100 to 150 nm were successfully synthesized in mixed solvents of ethylene glycol and distilled water. By changing stirring time, different morphologies of LiMnPO4 were prepared. Porous plates with the percentages of more than 70%, more than 50% and 25% porous ones were formed in sequence. The according rest parts were particles, less than 40% solid plates and 25% solid ones, respectively. Stirring time is the key cause influencing the nucleation rate and diffusion rate of the initial formed growth units of LiMnPO4. Through adjusting the factor, chemicals with specific morphology can be obtained in mixed solvents. The phase composition and microstructure were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. This synthetic route provides us a new idea to prepare new structure materials. PMID:24734766

Pei, Zhenzhao; Du, Jianghua; Gao, Xiang

2014-04-01

59

Spin-flopping in LiMnPO4 and Cr2BeO4  

Microsoft Academic Search

Pulsed-field spin flop measurements in the orthorhombic antiferromagnets LiMnPO4 and Cr2BeO4 are reported. In LiMnPO4 the data indicate a collinear spin array with [2lambdaK1\\/(1-alpha)]1\\/2 = 40.0 +\\/- 2.0 kG and [2lambda K2\\/(1-alpha)]1\\/2 = 66.5 +\\/- 3.0 kG at 4.2°K. For Cr2BeO4 the spin array is probably a spiral, and spin-flopping is observed for magnetic fields along two orthorhombic axes.

J. H. Ranicar; P. R. Elliston

1967-01-01

60

Synthesis of LiyMnSiOx and LiMnPO4 nanostructures  

NASA Astrophysics Data System (ADS)

Nanosized LiyMnSiOx and LiMnPO4 have been synthesized by a hydrothermal route. Simply by changing parameters such as metal precursors and/or template, high surface area LiyMnSiOx with different morphology and sizes were prepared, in particular hollow spheres and plate-like nanoparticles, however with poorly developed crystallinity. In the case of LiMnPO4, highly crystalline nanocrystals were prepared.Nanosized LiyMnSiOx and LiMnPO4 have been synthesized by a hydrothermal route. Simply by changing parameters such as metal precursors and/or template, high surface area LiyMnSiOx with different morphology and sizes were prepared, in particular hollow spheres and plate-like nanoparticles, however with poorly developed crystallinity. In the case of LiMnPO4, highly crystalline nanocrystals were prepared. Electronic supplementary information (ESI) available: FT-IR spectra of LiyMnSiOx prepared with different silica sources and different metal precursors; particles size distributions of LiyMnSiOx in the form of hollow spheres and plate-like nanoparticles; ICP technical details. See DOI: 10.1039/b9nr00149b

Milke, Bettina; Strauch, Peter; Antonietti, Markus; Giordano, Cristina

2009-09-01

61

First-principles study of surface properties of LiFePO4 : Surface energy, structure, Wulff shape, and surface redox potential  

Microsoft Academic Search

Using first-principles calculations within the generalized gradient approximation (GGA)+U framework, we investigate several surface properties of olivine structure LiFePO4 . Calculated surface energies and surface redox potentials are found to be very anisotropic. Low-energy surfaces are in the [1 0 0], [0 1 0], [0 1 1], [1 0 1], and [2 0 1] orientations of the orthorhombic structure. We

L. Wang; F. Zhou; Y. S. Meng; G. Ceder

2007-01-01

62

XRD simulation study of doped LiFePO 4  

Microsoft Academic Search

LiFePO4 has become a highly promising cathode material for use in the next generation of lithium-ion batteries, in which metal-doping is typically employed to improve the electrochemical properties. However, it is always difficult to resolve the issue that how the doping element and its position cause the microstructural changes and eventually influence the material properties. In this work, the X-ray

Dongyun Zhang; Peixin Zhang; Juan Yi; Qiuhua Yuan; Jianhui Jiang; Qiming Xu; Zhongkuan Luo; Xiangzhong Ren

2011-01-01

63

A novel synthesis and characterization of LiFePO4 and LiFePO4/C as a cathode material for lithium-ion battery  

NASA Astrophysics Data System (ADS)

A novel hydrothermal stripping technique is developed to synthesize pure LiFePO4 and LiFePO4/C cathode materials. The pure sample is directly synthesized by the cation exchange between the organic phase which is prepared with FeSO4·7H2O and naphthenic acid, and aqueous phase prepared with H3PO4 and LiOH. SEM exhibits that the primary sizes of the well-distributed LiFePO4 and LiFePO4/C particles are about 150 nm and 100 nm in diameter, respectively. TEM indicates the LiFePO4/C is uniformly coated with a carbon layer about 2.7 nm in size. The as-prepared LiFePO4 exhibits a high initial discharge capacity of 135.5 mAh g-1 at 0.1 C, and the LiFePO4/C composite sintered at 650 °C for 4 h exhibits the best electrode properties with discharge capacities of 151.7, 154.8, 149.8 and 139.1 mAh g-1 at 0.1 C, 0.2 C, 0.5 C and 1.0 C rates, respectively. In addition, the LiFePO4/C also shows excellent capacity retention and cycle performances.

Miao, Cui; Bai, Peifeng; Jiang, Qianqian; Sun, Shuqing; Wang, Xingyao

64

Magnetic and Diffusive Nature of LiFePO4  

NASA Astrophysics Data System (ADS)

In order to elucidate the magnetism and Li diffusion in LiFePO4, we have measured muon-spin rotation and relaxation (?+SR) spectra for a polycrystalline LiFePO4 sample in the temperature range between 1.8 and 500 K. Below TN ? 52 K, two oscillatory signals together with onefast relaxation signal were clearly found in the zero-field (ZF) ?+SR spectrum. The three signals are reasonably explained using an antiferromagnetic (AF) spin structure proposedby neutron measurements, because electrostatic potential calculations suggests multiple different muon sites in the LiFePO4 lattice. However, the AF ordered moment estimated from ?+SR was about 3/4 of that reported by neutron, probably due to a different time window between the two techniques. In the paramagnetic state, ZF-and longitudinal-field (LF-) ?+SR spectraexhibiteda dynamic nuclear field relaxation. From the temperature dependence of the field fluctuation rate, a diffusion coeffcient of Li+ ions (DLi) at300K was estimated about 3.6×10-10 cm2/s, assuming that diffusing Li+ ions jump between the regular site and interstitial sites.

Sugiyama, Jun; Nozaki, Hiroshi; Kamazawa, Kazuya; Ofer, Oren; MŒnsson, Martin; Ansaldo, Eduardo J.; Brewer, Jess H.; Chow, Kim H.; Watanabe, Isao; Ikedo, Yutaka; Miyake, Yasuhiro; Kobayashi, Genki; Kanno, Ryoji

65

Neutron Scattering Studies of LiCoPO4 & LiMnPO4  

NASA Astrophysics Data System (ADS)

LiCoPO4 (TN approx 21.8 K) & LiMnPO4 (TN approx 34 K) are antiferromagnetic insulators exhibiting large magnetoelectric effects. We performed inelastic neutron scattering (INS) experiments to investigate the spin dynamics of these systems and analyzed the measured magnetic spectra by linear spin-wave theory, taking into account intra- and inter-plane nearest, next nearest neighbor magnetic exchange interactions and single ion anisotropy. The INS results indicate that the single ion anisotropy in LiCoPO4 is comparable to the nearest-neighbor magnetic exchange interaction rendering Ising-type behavior of LiCoPO4. Neutron diffraction studies of LiMnPO4 in applied magnetic fields reveal a spin-flop transition at ~ 3.5 Tesla with characteristics of a second order phase transition.

Tian, Wei; Li, Jiying; Li, Haifeng; Lynn, Jeffrey W.; Zarestky, Jerel L.; Vaknin, David

2010-11-01

66

FTIR spectroscopy of a LiMnPO 4 composite cathode  

Microsoft Academic Search

A LixMnPO4 (x=1.0–0.15) composite cathode was investigated by Fourier-transform infrared spectroscopy at different states of charge. Significant spectral changes of the PO43? vibrations, which are correlated with the Jahn–Teller distortion of Mn3+ in MnPO4 and the 3rd ionization potential of Mn, were observed upon electrochemical delithiation of LiMnPO4. The presence of two sets of peaks observed in the series of

Nick S. Norberg; Robert Kostecki

2011-01-01

67

Effect of particle size on LiMnPO 4 cathodes  

Microsoft Academic Search

LiMnPO4 was synthesized using a sol–gel method and tested as a cathode material for lithium ion batteries. After calcination at temperatures between 520 and 600°C, primary particle sizes in the range of 140–220nm were achieved. Subsequent dry ball milling reduced the primary particle diameters from 130 to 90nm, depending on time of ball milling. Reversible capacities of 156mAhg?1 at C\\/100

Thierry Drezen; Nam-Hee Kwon; Paul Bowen; Ivo Teerlinck; Motoshi Isono; Ivan Exnar

2007-01-01

68

Effect of copper doping on LiMnPO 4 prepared via hydrothermal route  

Microsoft Academic Search

Fine-sized, well-crystallized LiMnPO4 and two Cu-doped derivatives (2% and 5% Cu2+ doping) are readily prepared via a hydrothermal route. X-ray diffraction (XRD) combined with structural analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area analysis, and galvanostatic charge–discharge tests are applied to characterize these materials. The structure analysis shows that only a negligible amount of Cu2+ ions

Jiangfeng Ni; Lijun Gao

2011-01-01

69

Neutron Scattering Studies of LiCoPO4 & LiMnPO4  

Microsoft Academic Search

LiCoPO4 (TN approx 21.8 K) & LiMnPO4 (TN approx 34 K) are antiferromagnetic insulators exhibiting large magnetoelectric effects. We performed inelastic neutron scattering (INS) experiments to investigate the spin dynamics of these systems and analyzed the measured magnetic spectra by linear spin-wave theory, taking into account intra- and inter-plane nearest, next nearest neighbor magnetic exchange interactions and single ion anisotropy.

Wei Tian; Jiying Li; Haifeng Li; Jeffrey W. Lynn; Jerel L. Zarestky; David Vaknin

2010-01-01

70

Single-crystal growth of LiMnPO 4 by the floating-zone method  

Microsoft Academic Search

LiMnPO4 crystals with orthorhombic Pnma crystal structure containing large grains have been grown successfully for the first time by the traveling-solvent floating-zone technique under elevated argon pressure. The grains achieve sizes of about 3mm2×10mm and display an orange transparent color. During the growth process, the traveling zone is continuously enriched with PO4- and Li-ions, due to the self-adjustment of the

Nadja Wizent; Günter Behr; Ferdinand Lipps; Ingo Hellmann; Rüdiger Klingeler; Vladislav Kataev; Wolfgang Löser; Norio Sato; Bernd Büchner

2009-01-01

71

Antiferromagnetism in the magnetoelectric effect single crystal LiMnPO4  

Microsoft Academic Search

Elastic and inelastic neutron-scattering studies reveal details of the antiferromagnetic transition and intriguing spin dynamics in the magnetoelectric effect single crystal LiMnPO4 . The elastic-scattering studies confirm that the system is antiferromagnetic below TN=33.75K with local magnetic moments ( Mn2+ ; S=5\\/2 ) that are aligned along the crystallographic a axis. The spin-wave dispersion curves propagating along the three principal

Jiying Li; Wei Tian; Ying Chen; Jerel L. Zarestky; Jeffrey W. Lynn; David Vaknin

2009-01-01

72

High-performance, nano-structured LiMnPO 4 synthesized via a polyol method  

Microsoft Academic Search

A novel polyol synthesis was adopted to synthesize nano-structured LiMnPO4. This route yields well-crystallized nanoparticles with platelet morphology that are only ?30nm thick oriented in the b direction. The obtained material presented a good rate behavior and a very long cyclic life both at room temperature (RT) and 50°C. The sample exhibited a specific capacity of 145mAhg?1 at C\\/20, 141mAhg?1

Deyu Wang; Hilmi Buqa; Michael Crouzet; Gianluca Deghenghi; Thierry Drezen; Ivan Exnar; Nam-Hee Kwon; James H. Miners; Laetitia Poletto; Michael Grätzel

2009-01-01

73

Ion dynamics in nanocrystalline LiMnPO4 synthesised by novel template free hydrothermal approach  

NASA Astrophysics Data System (ADS)

A dense core rectangular shaped nanocrystalline LiMnPO4 material was synthesized by template free sucrose assisted hydrothermal synthesis. The material possess orthorhombic crystal structure with Pnma, space group having four formula units. The structural characterization was accomplished through X-ray diffraction, thermo gravimetry/differential thermal analysis. Morphology was identified by the SEM, VSM was used to verify the magnetic behavior of the material and electrical characterization was done through impedance spectroscopy and the results were reported.

Vijayan, Lakshmi; Cheruku, Rajesh; Govindaraj, G.

2014-04-01

74

First-principles studies on surface electronic structure and stability of LiFePO 4  

Microsoft Academic Search

The stabilities and electronic structure of LiFePO4 (001), (010) and (100) surfaces have been studied using the first-principles method. Calculated cleavage energies show that LiFePO4 (010) is the most stable termination. Large differences in electronic density of states are observed between the LiFePO4 (001) and (100) surfaces comparing to the counterpart of the bulk, due to the broken symmetry at

Xiaofang Ouyang; Molin Lei; Siqi Shi; Cuilan Luo; Desheng Liu; Diyou Jiang; Zhiqing Ye; Minsheng Lei

2009-01-01

75

LiMnPO4Nanoplate Grown via Solid-State Reaction in Molten Hydrocarbon for Li-Ion Battery Cathode  

Microsoft Academic Search

Electrochemically active LiMnPO4 nanoplates have been synthesized via novel single step solid state reaction in molten hydrocarbon. The LiMnPO4 prepared show unique porous nanoplate shape ~50nm in thickness with highly preferred crystallographic orientation. The reversible cycling of carbon coated LiMnPO4 show flat potential at 4.1 V vs. Li with specific capacity reaching up to 168mAh\\/g and excellent cycling performance using

Daiwon Choi; Donghai Wang; In-Tae Bae; Jie Xiao; Zimin Nie; Wei Wang; Vilayanur V. Viswanathan; Yun Jung Lee; Ji-Guang Zhang; Gordon L. Graff; Zhenguo Yang; Jun Liu

2010-01-01

76

Morphology and agglomeration control of LiMnPO4 micro- and nanocrystals.  

PubMed

Microwave-assisted hydrothermal synthesis was used to grow LiMnPO4 micro- and nanocrystals from acetate precursors. By appropriate adjustment of the precursor concentration and the pH-value of the reactant, the product composition and purity along with the crystal size can be manipulated, resulting in particle-dimensions from around 10 ?m down to a few 100 nm. Prisms and plates with hexagonal basal faces as well as cuboid and rod-like particles were produced. The effects on the crystal morphology as well as on the materials texture and agglomeration tendency are discussed and a comprehensive agglomeration phase diagram is constructed. PMID:23691973

Neef, Christoph; Jähne, Carsten; Meyer, Hans-Peter; Klingeler, Rüdiger

2013-06-25

77

Electrochemical performance of nanocomposite LiMnPO 4\\/C cathode materials for lithium batteries  

Microsoft Academic Search

A LiMnPO4\\/C composite cathode was prepared by a combination of spray pyrolysis and wet ball milling. The cathode showed stable performance at various cutoff voltages up to 4.9V. The cutoff voltage increase up to 4.9V allowed the achievement of a high discharge capacity in galvanostatic charge–discharge tests. The discharge capacities of 153mAhg?1 at 0.05C and 149mAhg?1 at 0.1C were achieved

Zhumabay Bakenov; Izumi Taniguchi

2010-01-01

78

Ultrathin carbon nanopainting of LiFePO4 by oxidative surface polymerization of dopamine  

NASA Astrophysics Data System (ADS)

The common strategy to address the low electronic conductivity of LiFePO4 is to downsize LiFePO4 and to coat the nanocrystal with conductive carbon film. The major issues with existing carbon coating techniques are thickness and quality control. This paper reports a facile carbon coating method which can provide ultrathin, uniform and fully encapsulating carbon coating on LiFePO4. This coating method capitalizes on the redox chemistry of surface Fe3+ on solvothermally synthesized LiFePO4 nanocrystal, to deposit uniform thin films of polydopamine films. The polymer film is easily carbonized into ultrathin carbon film. The carbon coated LiFePO4 exhibits very high rate performance (143 mAh g-1 at current density of 1700 mA g-1) with excellent capacity retention.

Ding, Bo; Tang, Wei Chin; Ji, Ge; Ma, Yue; Xiao, Pengfei; Lu, Li; Lee, Jim Yang

2014-11-01

79

Mesoporous carbon-coated LiFePO4 nanocrystals co-modified with graphene and Mg2+ doping as superior cathode materials for lithium ion batteries  

NASA Astrophysics Data System (ADS)

In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg2+ doping (G/LFMP) were synthesized by a modified rheological phase method to improve the speed of lithium storage as well as cycling stability. The mesoporous structure of LiFePO4 nanocrystals was designed and realized by introducing the bead milling technique, which assisted in forming sucrose-pyrolytic carbon nanoparticles as the template for generating mesopores. For comparison purposes, samples modified only with graphene (G/LFP) or Mg2+ doping (LFMP) as well as pure LiFePO4 (LFP) were also prepared and investigated. Microscopic observation and nitrogen sorption analysis have revealed the mesoporous morphologies of the as-prepared composites. X-ray diffraction (XRD) and Rietveld refinement data demonstrated that the Mg-doped LiFePO4 is a single olivine-type phase and well crystallized with shortened Fe-O and P-O bonds and a lengthened Li-O bond, resulting in an enhanced Li+ diffusion velocity. Electrochemical properties have also been investigated after assembling coin cells with the as-prepared composites as the cathode active materials. Remarkably, the G/LFMP composite has exhibited the best electrochemical properties, including fast lithium storage performance and excellent cycle stability. That is because the modification of graphene provided active sites for nuclei, restricted the in situ crystallite growth, increased the electronic conductivity and reduced the interface reaction current density, while, Mg2+ doping improved the intrinsically electronic and ionic transfer properties of LFP crystals. Moreover, in the G/LFMP composite, the graphene component plays the role of ``cushion'' as it could quickly realize capacity response, buffering the impact to LFMP under the conditions of high-rate charging or discharging, which results in a pre-eminent rate capability and cycling stability.In this work, mesoporous carbon-coated LiFePO4 nanocrystals further co-modified with graphene and Mg2+ doping (G/LFMP) were synthesized by a modified rheological phase method to improve the speed of lithium storage as well as cycling stability. The mesoporous structure of LiFePO4 nanocrystals was designed and realized by introducing the bead milling technique, which assisted in forming sucrose-pyrolytic carbon nanoparticles as the template for generating mesopores. For comparison purposes, samples modified only with graphene (G/LFP) or Mg2+ doping (LFMP) as well as pure LiFePO4 (LFP) were also prepared and investigated. Microscopic observation and nitrogen sorption analysis have revealed the mesoporous morphologies of the as-prepared composites. X-ray diffraction (XRD) and Rietveld refinement data demonstrated that the Mg-doped LiFePO4 is a single olivine-type phase and well crystallized with shortened Fe-O and P-O bonds and a lengthened Li-O bond, resulting in an enhanced Li+ diffusion velocity. Electrochemical properties have also been investigated after assembling coin cells with the as-prepared composites as the cathode active materials. Remarkably, the G/LFMP composite has exhibited the best electrochemical properties, including fast lithium storage performance and excellent cycle stability. That is because the modification of graphene provided active sites for nuclei, restricted the in situ crystallite growth, increased the electronic conductivity and reduced the interface reaction current density, while, Mg2+ doping improved the intrinsically electronic and ionic transfer properties of LFP crystals. Moreover, in the G/LFMP composite, the graphene component plays the role of ``cushion'' as it could quickly realize capacity response, buffering the impact to LFMP under the conditions of high-rate charging or discharging, which results in a pre-eminent rate capability and cycling stability. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr04611g

Wang, Bo; Xu, Binghui; Liu, Tiefeng; Liu, Peng; Guo, Chenfeng; Wang, Shuo; Wang, Qiuming; Xiong, Zhigang; Wang, Dianlong; Zhao, X. S.

2013-12-01

80

Preparation of nanocrystalline LiMnPO 4 via a simple and novel method and its isothermal kinetics of crystallization  

Microsoft Academic Search

The precursor of nanocrystalline LiMnPO4 was obtained by solid-state reaction at low heat using Li2SO4·H2O, MnSO4·H2O, and Na3PO4·12H2O as raw materials, maintaining the mixture at 333 K for 4 h, and then washing the mixture with deionized water to remove\\u000a soluble inorganic salts, and at last drying at 373 K. The nanocrystalline LiMnPO4 was obtained by calcining the precursor. The precursor and its

Chen Liu; Xuehang Wu; Wenwei Wu; Jinchao Cai; Sen Liao

2011-01-01

81

Magnetic Phase Transition and Spin Dynamics in Magnetoelectric Effect LiMnPO4  

NASA Astrophysics Data System (ADS)

Elastic and inelastic neutron scattering techniques were used to study the magnetic phase transition and spin dynamics in single crystal LiMnPO4. In this mulitiferroic, antiferromagnetism coexists with induced ferroelectricity below the Neel temperature. Elastic neutron scattering technique confirmed that LiMnPO4 has a collinear antiferromagnetic ground state with magnetic moments oriented along the a-axis. The temperature dependent order parameter, calculated from the integrated intensity of the (010) magnetic reflection, was fit to a power law equation, yielding a transition temperature TN = 33.7 K and a critical exponent of ? = 0.114. Above the Neel temperature, in the paramagnetic phase, unusually strong magnetic fluctuations were observed to temperatures as high as 60 K. The correlation lengths in the MnO layer and between the layers were also determined. The spin-wave dispersion curves along a- and b-axis were measured in the antiferromagnetic state at 4.5 K and the system was shown to be quasi-2D by analyzing the dispersion curves using a 3D Heisenberg model from linear spin wave theory.

Li, J.; Tain, W.; Zarestky, J. L.; Vaknin, D.; Chen, Y.; Lynn, J. W.

2007-03-01

82

Spin Dynamics and Spin-flop transition in Magnetoelectric Effect LiMnPO4  

NASA Astrophysics Data System (ADS)

Neutron scattering techniques were used to study the magnetic phase transition and spin dynamics in single crystal LiMnPO4 both with and without magnetic field. Elastic scattering confirmed that LiMnPO4 has a collinear antiferromagnetic ground state with moments along a-axis in zero-field. The temperature dependent order parameter, calculated from the integrated intensity of the (010) magnetic reflection, was fit to a power law equation, yielding a transition temperature TN = 33.8 K. By applying magnetic field along the a-axis, the moments rotate from a-axis to the c-axis at a critical field of 3.5 Tesla at 5 K. The field dependent (100) and (001) intensities indicate a complicated intermediate state between the ground state and the spin-flop state. The critical field increased from 3.5 Tesla at 5 K to 4.5 Tesla near the transition TN. Spin-wave dispersion curves along the three principal axes were measured in the antiferromagnetic state at 4.5 K in zero magnetic field and were analyzed using a 3D Heisenberg model.

Li, J.; Tian, W.; Chen, Y.; Zarestky, J. L.; Vaknin, D.; Lynn, J. W.

2008-03-01

83

Comparison of LiFePO4 from different sources  

SciTech Connect

The lithium iron phosphate chemistry is plagued by the poor conductivity and slow lithium diffusion in the solid phase. In order to alleviate these problems, various research groups have adopted different strategies including decreasing the particle sizes, increasing the carbon content, and adding dopants. In this study we obtained LiFePO4 electrodes from six different sources and used a combined model-experimental approach to compare the performance. Samples ranged from one with no carbon coating to one with 15 percent coating. In addition, particle sizes varied by as much as a order of magnitude between samples. The study detailed in this manuscript allows us to provide insight into the relative importance of the conductivity of the samples compared to the particle size, the impact of dopant on performance and ideas for making materials in order to maximize the power capability of this chemistry.

Striebel, Kathryn; Shim, Joongpyo; Srinivasan, Venkat; Newman, John

2003-11-25

84

Electrochemical performance of patterned LiFePO4 nano-electrode with a pristine amorphous layer  

NASA Astrophysics Data System (ADS)

A patterned LiFePO4 nanorod with a pristine amorphous LiFePO4 surface layer was fabricated by controlling the temperature gradient from the interior to the exterior layer in high-temperature annealing process through designing hierarchical multilayer electrode structure. The three dimensional patterned LiFePO4 nanorods were prepared using tobacco mosaic virus nanoforest arrays. The results indicate that the nano-electrodes nearly reached the theoretical capacity at a very low C rate even without conductive coatings. The amorphous LiFePO4 can fast transport the Li-ion to inside crystal LiFePO4, thus enhancing the rate capability.

Wang, Mao; Zhang, Wei; Liu, Yihang; Yang, Yong; Wang, Chunsheng; Wang, Yuan

2014-04-01

85

Monodispersed LiFePO4@C core-shell nanostructures for a high power Li-ion battery cathode  

NASA Astrophysics Data System (ADS)

In this paper, monodispersed LiFePO4 nanopillows have been successfully synthesized via solvothermal route with ethylene glycol (EG) as reaction medium. Subsequently, with the basis of the solvothermally synthesized monodispersed LiFePO4 nanopillows, monodispersed LiFePO4@C core-shell nanostructures are facilely prepared in high yield. Based on the experimental results, the formation mechanism of the monodispersed LiFePO4 nanopillows has been discussed simply. The monodispersed LiFePO4@C core-shell nanostructures exhibit nice capacity retention and high rate capacity due to the full carbon-coating and the well-crystallized nanosized particles.

Xu, Gang; Li, Feng; Tao, Zhihong; Wei, Xiao; Liu, Yong; Li, Xiang; Ren, Zhaohui; Shen, Ge; Han, Gaorong

86

The Li intercalation potential of LiMPO4 and LiMSiO4 olivines with M = Fe, Mn, Co, Ni  

Microsoft Academic Search

The Li intercalation potential of LiMPO4 and LiMSiO4 compounds with M = Fe, Mn, Co, and Ni is computed with the GGA+U method. It is found that this approach is considerably more accurate than standard LDA or GGA methods. The calculated potentials for LiFePO4, LiMnPO4 and LiCoOPO4 agree to within 0.1 V with experimental results. The LiNiPO4 potential is predicted

Fei Zhou; Matteo Cococcioni; Kisuk Kang; Gerbrand Ceder

2005-01-01

87

The Li intercalation potential of LiMPO 4 and LiMSiO 4 olivines with M = Fe, Mn, Co, Ni  

Microsoft Academic Search

The Li intercalation potential of LiMPO4 and LiMSiO4 compounds with M=Fe, Mn, Co and Ni is computed with the GGA+U method. It is found that this approach is considerably more accurate than standard LDA or GGA methods. The calculated potentials for LiFePO4, LiMnPO4 and LiCoPO4 agree to within 0.1 V with experimental results. The LiNiPO4 potential is predicted to be

Fei Zhou; Matteo Cococcioni; Kisuk Kang; Gerbrand Ceder

2004-01-01

88

Antiferromagnetism in the magnetoelectric effect single crystal LiMnPO4  

NASA Astrophysics Data System (ADS)

Elastic and inelastic neutron-scattering studies reveal details of the antiferromagnetic transition and intriguing spin dynamics in the magnetoelectric effect single crystal LiMnPO4 . The elastic-scattering studies confirm that the system is antiferromagnetic below TN=33.75K with local magnetic moments ( Mn2+ ; S=5/2 ) that are aligned along the crystallographic a axis. The spin-wave dispersion curves propagating along the three principal axes, determined by inelastic scattering, are adequately modeled in the linear spin-wave framework assuming a spin Hamiltonian that is parametrized by inter- and in-plane nearest- and next-nearest-neighbor interactions and by easy-plane anisotropy. The temperature dependence of the spin dynamics makes this an excellent model many-body spin system to address the question of the relationship between spin-wave excitations and the order parameter.

Li, Jiying; Tian, Wei; Chen, Ying; Zarestky, Jerel L.; Lynn, Jeffrey W.; Vaknin, David

2009-04-01

89

Reaction behavior of LiFePO 4 as a cathode material for rechargeable lithium batteries  

Microsoft Academic Search

We investigated the effect of cell temperature on the electrochemical reaction behavior of LiFePO4. We evaluated its electrochemical characteristics by using cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Both the electron transfer activity and the lithium ion diffusion rate in the LiFePO4 electrode increased as we increased the operating temperature. The apparent activation energy for the lithium diffusion was more

Masaya Takahashi; Shin-ichi Tobishima; Koji Takei; Yoji Sakurai

2002-01-01

90

LiMnPO4 Nanoplate Grown via Solid-State Reaction in Molten Hydrocarbon for Li-ion Battery Cathode  

SciTech Connect

Electrochemically active LiMnPO4 nanoplates have been synthesized via novel single step solid state reaction in molten hydrocarbon. The LiMnPO4 prepared show unique porous nanoplate shape ~50nm in thickness with highly preferred crystallographic orientation. The reversible cycling of carbon coated LiMnPO4 show flat potential at 4.1 V vs. Li with specific capacity reaching up to 168mAh/g and excellent cycling performance using only galvanostatic charging / discharging mode.

Choi, Daiwon; Wang, Donghai; Bae, In-Tae; Xiao, Jie; Nie, Zimin; Wang, Wei; Viswanathan, Vilayanur V.; Lee, Yun Jung; Zhang, Jiguang; Graff, Gordon L.; Yang, Zhenguo; Liu, Jun

2010-08-11

91

LiMn1-xFexPO4 Nanorods Grown on Graphene Sheets for UltraHigh Rate Performance Lithium Ion Batteries  

Microsoft Academic Search

Following the successful utilization of LiFePO4 as a novel cathode material for rechargeable lithium batteries, interest and efforts have grown in the research of another olivine structured material LiMnPO4 due to its higher operating potential voltage and energy density. However, high rate performance for LiMnPO4-based cathode materials has been challenging due to its extremely low electrical and ionic conductivities. Here,

Hailiang Wang; Yuan Yang; Yongye Liang; Li-Feng Cui; Hernan Sanchez Casalongue; Yanguang Li; Guosong Hong; Yi Cui; Hongjie Dai

2011-01-01

92

Dispersion properties of aqueous-based LiFePO 4 pastes and their electrochemical performance for lithium batteries  

Microsoft Academic Search

Aqueous-based LiFePO4 pastes to fabricate the cathode of lithium-ion battery were investigated with an emphasis on chemical control of suspension component interactions among LiFePO4 particulates, carbon black, carboxymethyl cellulose (CMC), and poly(acrylic acid) (PAA). The dispersion properties of LiFePO4 were characterized using electroacoustic, flow behavior and green microstructural observation. Correlation was made between the dispersion properties and electrochemical performance of

Jin-Hyon Lee; Jeom-Soo Kim; Yoon Chang Kim; Dong Sik Zang; Ungyu Paik

2008-01-01

93

Kinetic Behavior of LiFePO4/C Thin Film Cathode Material for Lithium-Ion Batteries  

NASA Astrophysics Data System (ADS)

LiFePO4 was prepared in a solid state synthesis with various levels of carbon content. LiFePO4/C thin films were obtained via magnetron sputtering. The surface morphology and structure was examined. Electrochemical properties of LiFePO4/C were studied, by using cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy. Thin films acquired show a potential use as a cathode in lithium ion batteries, displaying charge capacity up to 34 mAh g-1.

Kucinskis, Gints; Bajars, Gunars; Kleperis, Janis; Smits, Janis

2010-01-01

94

Exchange Constants from Combined Light and Neutron Scattering Experiments: Application to Magnetoelectric LiMnPO4  

NASA Astrophysics Data System (ADS)

Two-magnon Raman scattering is observed in magnetoelectric LiMnPO4, carrying quantitative information on the magnetic interactions between local Mn^2+ moments. A simulated annealing fitting procedure using these Raman data combined with magnon dispersion curves from neutron diffraction is demonstrated to greatly improve the accuracy and reliability of the determined exchange constants up to at least fifth-nearest neighbors. First-nearest neighbor interactions are shown to be largely dominant in LiMnPO4, ruling out magnetic frustration as a relevant ingredient for this material. This methodology may be instrumental to investigate other magnetoelectric and multiferroic materials as well as superconductors at the border of magnetism, where knowledge of exchange constants without ambiguity is important to pin down the relevant physics.

Calderon Filho, Cesar J.; Gomes, Paulo F.; García-Flores, Ali F.; Barberis, Gaston E.; Vaknin, David; Granado, Eduardo

2013-03-01

95

Challenges in the crystal growth of Li 2CuO 2 and LiMnPO 4  

Microsoft Academic Search

Single crystals of a potential battery material, LiMnPO4, and the spin ladder compound Li2CuO2 are grown under elevated gas pressure in a newly designed vertical floating zone facility with optical heating. Lithium vaporization and its reaction with gases in the growth chamber are principal challenges of the growth process. By applying high argon pressure of 40bar during Travelling Solvent Floating

Nadja Wizent; Günter Behr; Wolfgang Löser; Bernd Büchner; Rüdiger Klingeler

2011-01-01

96

The effects of calcination temperature on the electrochemical performance of LiMnPO 4 prepared by ultrasonic spray pyrolysis  

Microsoft Academic Search

Carbon-coated LiMnPO4 powders were prepared by ultrasonic spray pyrolysis. The effects of calcination temperature on the microstructure and electrochemical performance of C-LiMnPO4 were investigated. X-ray diffraction (XRD) studies showed that the crystallite size varied with calcination temperature. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that the calcination temperature had a strong influence on the morphology of

Seung-Min Oh; Sung Woo Oh; Seung-Taek Myung; Sung-Man Lee; Yang-Kook Sun

2010-01-01

97

Synthesis, crystal structure, and electrode characteristics of LiMnPO4(OH) cathode for lithium batteries  

NASA Astrophysics Data System (ADS)

The electrochemical properties of lithium manganese hydroxyphosphate, LiMnPO4(OH), with the tavorite structure have been investigated to assess its suitability as a cathode material for lithium batteries. Stoichiometric LiMnPO4(OH) was synthesized by an ion-exchange reaction with MnPO4·H2O and LiNO3. Lithium (de)intercalation reaction was observed for the first time in the trivalent LiMnPO4(OH), and it exhibited a reversible capacity of 110 mA h g-1 with an average cell voltage of 3.4 V (vs. Li) after an irreversible phase change during the first charge process. The crystal structure has been refined at room temperature by neutron and synchrotron X-ray diffraction data using Rietveld method with a space group of P-1. The hydroxy group at a bottleneck may reduce the attraction force between lithium and the bottleneck oxygen ions that thus increase the ion mobility along the lithium diffusion tunnel.

Yang, Yang; Hirayama, Masaaki; Yonemura, Masao; Kanno, Ryoji

2012-03-01

98

Impacts of different polymer binders on electrochemical properties of LiFePO4 cathode  

NASA Astrophysics Data System (ADS)

Impacts of different polymer binders (PVdF, PAA and PMMA) on electrochemical performance of the LiFePO4 cathode in Li-ion batteries are investigated. From CV result, the voltage between redox peaks of the LiFePO4 with PVdF, PAA and PMMA binders are 0.26, 0.20 and 0.23 V, respectively. The current of the LiFePO4 with PMMA binder shows the highest value of 1.4 mA. The apparent diffusion coefficient of the LiFePO4 with PVdF, PAA and PMMA binders is 8.30 × 10-12, 2.57 × 10-11 and 9.13 × 10-11 cm2 s-1, respectively. The discharge capacities of the LiFePO4 with PVdF, PAA and PMMA binders are 106, 143 and 154 mAh g-1 at an initial cycle, respectively. FE-SEM studies clearly demonstrate that plate-like PAA and PMMA coating on the electrodes form a protective film, which may decrease the amount of the deposits, thus decreasing crack and crystallization on the electrode surface. Achieved results indicate that PVdF, PAA and PMMA binders show better properties than the traditional one, especially PMMA one.

Nguyen, Van Hiep; Wang, Wan Lin; Jin, En Mei; Gu, Hal-Bon

2013-10-01

99

Coating the Conductivity Materials to Improving the Electrochemical Properties of LiFePO4  

NASA Astrophysics Data System (ADS)

LiFePO4 cathode materials were prepared by a solid-state method followed by one-step heat treatment. To improve the electrochemical properties of the LiFePO4, acetylene black (AB), citric acid (CA), and pyrene are added as carbon source, respectively. The cyclic voltammetry (CV), AC impedance and galvanostatic charge/discharge testing results showed that using the LiFePO4-C composite such as the AB carbon source exhibits higher discharge capacity and stability than the other composite. Synthesized LiFePO4-C/Li cells (with AB) showed that initial discharge capacity was 140.65 mA h g-1 and at the 2nd cycle were 145.87 mA h g-1, respectively. Morphology and electrochemical performance of the LiFePO4 cathode materials were investigated. Furthermore, the cell was subjected to current density studies (0.1 mA cm-2) that suggested excellent capacity retention of the cell at 25°C.

Wang, Wan Lin; Jin, En Mei; Gu, Hal-Bon

2013-02-01

100

Kinetics of non-equilibrium lithium incorporation in LiFePO4  

NASA Astrophysics Data System (ADS)

Lithium-ion batteries are a key technology for multiple clean energy applications. Their energy and power density is largely determined by the cathode materials, which store Li by incorporation into their crystal structure. Most commercialized cathode materials, such as LiCoO2 (ref. ), LiMn2O4 (ref. ), Li(Ni,Co,Al)O2 or Li(Ni,Co,Mn)O2 (ref. ), form solid solutions over a large concentration range, with occasional weak first-order transitions as a result of ordering of Li or electronic effects. An exception is LiFePO4, which stores Li through a two-phase transformation between FePO4 and LiFePO4 (refs , , , ). Notwithstanding having to overcome extra kinetic barriers, such as nucleation of the second phase and growth through interface motion, the observed rate capability of LiFePO4 has become remarkably high. In particular, once transport limitations at the electrode level are removed through carbon addition and particle size reduction, the innate rate capability of LiFePO4 is revealed to be very high. We demonstrate that the reason LiFePO4 functions as a cathode at reasonable rate is the availability of a single-phase transformation path at very low overpotential, allowing the system to bypass nucleation and growth of a second phase. The LixFePO4 system is an example where the kinetic transformation path between LiFePO4 and FePO4 is fundamentally different from the path deduced from its equilibrium phase diagram.

Malik, Rahul; Zhou, Fei; Ceder, G.

2011-08-01

101

Carbon Surface Layers on a High-Rate LiFePO4  

SciTech Connect

Transmission electron microscopy (TEM) was used to image particles of a high-rate LiFePO4 sample containing a small amount of in situ carbon. The particle morphology is highly irregular, with a wide size distribution. Nevertheless, coatings, varying from about 5-10 nm in thickness, could readily be detected on surfaces of particles as well as on edges of agglomerates. Elemental mapping using Energy Filtered TEM (EFTEM) indicates that these very thin surface layers are composed of carbon. These observations have important implications for the design of high-rate LiFePO4 materials in which, ideally, a minimal amount of carbon coating is used.

Gabrisch, Heike; Wilcox, James D.; Doeff, Marca M.

2005-09-06

102

TEM Studies of Carbon Coated LiFePO4 after Charge DischargeCycling  

SciTech Connect

Carbon coating has proven to be a successful approach toimprove the rate capability of LiFePO4 used in rechargeable Li-ionbatteries. Investigations of the microstructure of carbon coated LiFePO4after charge discharge cycling shows that the carbon surface layerremains intact over 100 cycles. We find micro cracks in the cycledmaterial that extend parallel to low indexed lattice planes. Ourobservations differ from observations made by other authors. However thedifferences between the orientations of crack surfaces in both studiescan be reconciled considering the location of weak bonds in the unit celland specimen geometry as well as elastic stress fields ofdislocation.

Gabrisch, H.; Wilcox, J.; Doeff, M.

2006-11-30

103

LiFePO4 nanoparticles encapsulated in graphene nanoshells for high-performance lithium-ion battery cathodes.  

PubMed

LiFePO4 encapsulated in graphene nanoshells (LiFePO4@GNS) nanoparticles were synthesized by solid state reaction between graphene-coated Fe nanoparticles and LiH2PO4. The resulting nanocomposite was demonstrated to be a superior lithium-ion battery cathode with improved cycle and rate performances. PMID:24853817

Fei, Huilong; Peng, Zhiwei; Yang, Yang; Li, Lei; Raji, Abdul-Rahman O; Samuel, Errol L G; Tour, James M

2014-06-10

104

Porous LiFePO4/C microspheres as high-power cathode materials for lithium ion batteries.  

PubMed

Porous LiFePO4/C microspheres were synthesized by a novel hydrothermal reaction combined with high-temperature calcinations. The morphology of the prepared material was investigated by field-emission scanning electron microscopy. Porous microspheres with diameters around 1-3 microm were obtained, which consisting of primary LiFePO4 nanoparticles. The electrochemical performances of the as-prepared LiFePO4 microspheres were evaluated by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge cycling. The carbon coated LiFePO4 microspheres showed lower polarization, higher rate capability, and better cycling stability than that of pristine LiFePO4 microspheres, indicating the potential application as the cathode material for high-power lithium ion batteries. PMID:23858922

Sun, Bing; Wang, Ying; Wang, Bei; Kim, Hyun-Soo; Kim, Woo-Seong; Wang, Guoxiu

2013-05-01

105

Hierarchical LiFePO4 with a controllable growth of the (010) facet for lithium-ion batteries  

PubMed Central

Hierarchically structured LiFePO4 was successfully synthesized by ionic liquid solvothermal method. These hierarchically structured LiFePO4 samples were constructed from nanostructured platelets with their (010) facets mainly exposed. To the best of our knowledge, facet control of a hierarchical LiFePO4 crystal has not been reported yet. Based on a series of experimental results, a tentative mechanism for the formation of these hierarchical structures was proposed. After these hierarchically structured LiFePO4 samples were coated with a thin carbon layer and used as cathode materials for lithium-ion batteries, they exhibited excellent high-rate discharge capability and cycling stability. For instance, a capacity of 95% can be maintained for the LiFePO4 sample at a rate as high as 20 C, even after 1000 cycles.

Guo, Binbin; Ruan, Hongcheng; Zheng, Cheng; Fei, Hailong; Wei, Mingdeng

2013-01-01

106

Preparation and characterization of SnO2 and Carbon Co-coated LiFePO4 cathode materials.  

PubMed

The SnO2 and carbon co-coated LiFePO4 cathode materials were successfully synthesized by solid state method. The microstructure and morphology of LiFePO4 composites were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscope. The results showed that the SnO2 and carbon co-coated LiFePO4 cathode materials exhibited more uniform particle size distribution. Compared with the uncoated LiFePO4/C, the structure of LiFePO4 with SnO2 and carbon coating had no change. The existence of SnO2 and carbon coating layer effectively enhanced the initial discharge capacity. Among the investigated samples, the one with DBTDL:LiFePO4 molar ratios of 7:100 exhibited the best electrochemical performance. PMID:24734770

Wang, Haibin; Liu, Shuxin; Huang, Yongmao

2014-04-01

107

Solid Solution Phases in the Olivine-Type LiMnPO4\\/MnPO4 System  

Microsoft Academic Search

Nonstoichiometry is reported in the LiMnPO\\/MnPO system for the first time. As lithium is removed from crystalline LiMnPO by chemical or electrochemical methods, the resulting two phase mixture consists of stoichiometric LiMnPO and a delithiated phase, Li{sub y}MnPO, whose lattice parameters depend upon the global extent of delithiation and on the crystalline domain size of the delithiated phase. This behavior

Guoying Chen; Thomas J. Richardson

2009-01-01

108

Mössbauer study on LiFePO4 cathode material for lithium ion batteries  

Microsoft Academic Search

Crystalline LiFePO4 has been synthesized using solid-state, spray pyrolysis, and wet chemical methods. The crystal parameters were obtained from Rietveld's refinement methods of the X-ray diffraction patterns. A detailed investigation of the Fe valency carried out using Mössbauer spectroscopy at room temperature indicates that Fe is predominantly present in its bivalent state.

B. Hannoyer; A. A. M. Prince; M. Jean; R. S. Liu; G. X. Wang

2007-01-01

109

Performance and characteristic research in LiFePO4 battery for electric vehicle applications  

Microsoft Academic Search

LiFePO4 battery is tested in the research. The capacity, DCR, OCV are evaluated at different ambient temperature. The voltage hysteresis test is conducted by using the simulated current profiles from a HEV models. The result is discussed with some recommendation on the application of this battery in the electric vehicle.

Wang Jiayuan; Sun Zechang; Wei Xuezhe

2009-01-01

110

Electrochemical performances of LiMnPO4 synthesized from non-stoichiometric Li/Mn ratio.  

PubMed

In this paper, the influences of the lithium content in the starting materials on the final performances of as-prepared Li(x)MnPO(4) (x hereafter represents the starting Li content in the synthesis step which does not necessarily mean that Li(x)MnPO(4) is a single phase solid solution in this work.) are systematically investigated. It has been revealed that Mn(2)P(2)O(7) is the main impurity when Li < 1.0 while Li(3)PO(4) begins to form once x > 1.0. The interactions between Mn(2)P(2)O(7) or Li(3)PO(4) impurities and LiMnPO(4) are studied in terms of the structural, electrochemical, and magnetic properties. At a slow rate of C/50, the reversible capacity of both Li(0.5)MnPO(4) and Li(0.8)MnPO(4) increases with cycling. This indicates a gradual activation of more sites to accommodate a reversible diffusion of Li(+) ions that may be related to the interaction between Mn(2)P(2)O(7) and LiMnPO(4) nanoparticles. Among all of the different compositions, Li(1.1)MnPO(4) exhibits the most stable cycling ability probably because of the existence of a trace amount of Li(3)PO(4) impurity that functions as a solid-state electrolyte on the surface. The magnetic properties and X-ray absorption spectroscopy (XAS) of the MnPO(4)·H(2)O precursor, pure and carbon-coated Li(x)MnPO(4) are also investigated to identify the key steps involved in preparing a high-performance LiMnPO(4). PMID:21909564

Xiao, Jie; Chernova, Natasha A; Upreti, Shailesh; Chen, Xilin; Li, Zheng; Deng, Zhiqun; Choi, Daiwon; Xu, Wu; Nie, Zimin; Graff, Gordon L; Liu, Jun; Whittingham, M Stanley; Zhang, Ji-Guang

2011-10-28

111

Electrochemical Performances of LiMnPO4 Synthesized from Non-Stoichiometric Li/Mn Ratio  

SciTech Connect

In this paper we report the influences of the initial lithium content on the structural, electrochemical and magnetic properties of nonstoichiometric LixMnPO4 (0.5?x?1.2) nano-particles. It has been revealed Mn2P2O7 is the main impurity when Li<1.0 while Li3PO4 begins to form once x>1.0. The different functions of Mn2P2O7 and Li3PO¬4 impurities in the non-stoichiometric compounds have been investigated systematically. At a slow rate of C/50 the reversible capacity of both Li0.5MnPO4 and Li0.8MnPO4 increases with cycling indicating a gradual activation of more sites to accommodate a reversible diffusion of Li+ ions which may be related to the interaction between Mn2P2O7 and LiMnPO4 nanoparticles. Among all the different compositions, Li1.1MnPO4 exhibits the most stable cycling ability probably due to the existence of a trace amount of Li3PO4 impurity which functions as a solid state electrolyte on the surface. The magnetic properties and X-ray absorption spectroscopy (XAS) of MnPO4?H2O precursor, pure and carbon coated LiMnPO4 and all the other non-stoichiometric LixMnPO4 are also investigated to identify the key steps to prepare a high performance LiMnPO4.

Xiao, Jie; Chernova, Natalya; Upreti, Shailesh; Chen, Xilin; Li, Zheng; Deng, Zhiqun; Choi, Daiwon; Xu, Wu; Nie, Zimin; Graff, Gordon L.; Liu, Jun; Whittingham, M. S.; Zhang, Jiguang

2011-09-12

112

Oleic acid-assisted preparation of LiMnPO 4 and its improved electrochemical performance by Co doping  

Microsoft Academic Search

LiMnPO4, with a particle size of 50–150 nm, was prepared by oleic acid-assisted solid-state reaction. The materials were characterized\\u000a by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The electrochemical\\u000a properties of the materials were investigated by galvanostatic cycling. It was found that the introduction of oleic acid in\\u000a the precursor led to smaller particle size and more

Zhao Yang; Gao-Shao Cao; Jian Xie; Xin-Bing Zhao

113

Lithium extraction\\/insertion in LiFePO 4: an X-ray diffraction and Mössbauer spectroscopy study  

Microsoft Academic Search

The extraction and insertion of lithium in solid-state synthesized LiFePO4 has been followed by in situ X-ray diffraction and Mössbauer spectroscopy in ‘coffee-bag’ cells of type ?Li-metal | liq. el. | LiFePO4? during the first cycle. Two-phase Rietveld refinement of the X-ray diffractograms gives the triphylite (LiFePO4) to heterosite (FePO4) phase-ratios as charging and discharging of the cell proceeds. The

Anna S Andersson; Beata Kalska; Lennart Häggström; John O Thomas

2000-01-01

114

The development of low cost LiFePO4-based high power lithium-ion batteries  

SciTech Connect

The cycling performance of low-cost LiFePO4-based high-power lithium-ion cells was investigated and the components were analyzed after cycling to determine capacity fade mechanisms. Pouch type LiFePO4/natural graphite cells were assembled and evaluated by constant C/2 cycling, pulse-power and impedance measurements. From post-test electrochemical analysis after cycling, active materials, LiFePO4 and natural graphite, showed no degradation structurally or electrochemically. The main reasons for the capacity fade of cell were lithium inventory loss by side reaction and possible lithium deposition on the anode.

Shim, Joongpyo; Sierra, Azucena; Striebel, Kathryn A.

2003-11-25

115

Nanocomposite of LiFePO4 and mesoporous carbon prepared by microwave heating for rechargeable lithium batteries  

NASA Astrophysics Data System (ADS)

A nanocomposite of LiFePO4 and mesoporous carbon was synthesized from MgO-templated mesoporous carbon by microwave heating for use as a cathode material in rechargeable Li batteries. Our research group reported a composition method using a porous template in the a previous paper.[1] Despite its low carbon content, the present composite shows better electrochemical performance than our previously reported version. The LiFePO4 nanoparticles were homogeneously dispersed in the template because of the suppressed growth of LiFePO4 crystals in the template pores and small thermal gradient resulting from microwave heating. The three-dimensional conducting carbon network between the LiFePO4 nanoparticles led to excellent cycling stability and rate capability. No decrease in discharge capacity was observed up to 100 cycles, and 85% of the reversible capacity at a Crate of 0.1 was retained at a C-rate of 30.

Roh, Kwang Chul; Lee, Ho Jun; Lee, Jae-Won

2013-11-01

116

Single-Crystalline LiFePO4 Nanosheets for High-Rate Li-Ion Batteries.  

PubMed

The lithiation/delithiation in LiFePO4 is highly anisotropic with lithium-ion diffusion being mainly confined to channels along the b-axis. Controlling the orientation of LiFePO4 crystals therefore plays an important role for efficient mass transport within this material. We report here the preparation of single crystalline LiFePO4 nanosheets with a large percentage of highly oriented {010} facets, which provide the highest pore density for lithium-ion insertion/extraction. The LiFePO4 nanosheets show a high specific capacity at low charge/discharge rates and retain significant capacities at high C-rates, which may benefit the development of lithium batteries with both favorable energy and power density. PMID:24730515

Zhao, Yu; Peng, Lele; Liu, Borui; Yu, Guihua

2014-05-14

117

Controllable synthesis, morphology evolution and electrochemical properties of LiFePO4 cathode materials for Li-ion batteries.  

PubMed

Monodispersed LiFePO4 nanocrystals with diverse morphologies were successfully synthesized via a mild and controllable solvothermal approach with a mixture of ethylene glycol and oleic acid as the solvent. Morphology evolution of LiFePO4 nanoparticles from nanoplates to nanorods can be simply realized by varying the volume ratio of oleic acid to ethylene glycol. Moreover, the mechanism of competitive adsorption between ethylene glycol and oleic acid was proposed for the formation of different morphologies. Electrochemical measurements show that the LiFePO4/C nanorods have an initial discharge capacity of 155 mA h g(-1) at 0.5 C with a capacity retention of 80% at a high rate of 5 C, which confirms that LiFePO4/C nanorods exhibit excellent rate capability and cycling stability. PMID:24638079

Song, Jianjun; Wang, Lin; Shao, Guangjie; Shi, Meiwu; Ma, Zhipeng; Wang, Guiling; Song, Wei; Liu, Shuang; Wang, Caixia

2014-05-01

118

Simultaneous enhancement of electronic and Li+ ion conductivity in LiFePO4  

NASA Astrophysics Data System (ADS)

The electronic conductivity is generally highly sensitive to the electronic properties of a material while the ionic conductivity is mainly sensitive to the structural properties. Thus, the simultaneous control of both is very challenging. Furthermore, many electrochemical systems for advanced energy technologies require materials in which both ionic and electronic conductivities are optimized. Here we explore the influence of biaxial strain on the electronic and Li^+ ion conductivities of the battery cathode material LiFePO4 by performing first-principles calculations. We show that biaxial tensile strain leads to simultaneous increases in electronic and ionic conductivities of LiFePO4. The results unveil a generic mechanism that should be present in other materials with polaronic transport and provide a promising new approach to enhance the performance of energy-related materials.

Lee, Jaekwang; Pennycook, Stephen J.; Pantelides, Sokrates T.

2012-02-01

119

Analysis of the thermal behavior of a LiFePO4 battery cell  

NASA Astrophysics Data System (ADS)

This paper presents theory, experiments and numerical modeling results for the electrothermal analysis of Lithium Iron Phosphate (LiFePO4) battery cells. Thermal management of batteries is important for several reasons including thermal runaway and maintaining battery operating time. A battery pack is comprised of battery cells which are stacked together without cooling surfaces except for the pack outer surface. The central cells in the pack are therefore exposed to the risk of overheating. A model for a single specific commercial LiFePO4 battery cell is presented together with preliminary experiments and results for determination of heating sources during charging and discharging. Based on the experimental results we extract model parameters for use in the model. The experiments lead to relations for the cell surface temperature and the lump temperature of the cell. A reasonable agreement between experiments and the model is found and suggestions for further work is indicated.

Niculu??, Marian-Ciprian; Veje, Christian

2012-11-01

120

Characterization of LiFePO4/C Composite Thin Films Using Electrochemical Impedance Spectroscopy  

NASA Astrophysics Data System (ADS)

The composite LiFePO4/C thin films were prepared on steel substrate by radio frequency (RF) magnetron sputtering. Electrochemical properties of the obtained thin films were investigated by cyclic voltammetry charge-discharge measurements and electrochemical impedance spectroscopy (EIS). The films annealed at 550 °C exhibited a couple of redox peaks at 3.45 V vs. Li/Li+ characteristic for the electrochemical lithium insertion/extraction in LiFePO4. At low current rate such composite thin film showed a discharge capacity of over 110 mAh g-1. The dependence of charge transfer resistance, double layer capacitance and lithium diffusion coefficients on applied electrode potential were calculated from EIS data. Determined values of lithium diffusion coefficient were in the range from 8.3-10-13 cm2 s1 to 1.2-10-13 cm2 s-1 at 3.4 V and 3.7 V, respectively.

Bajars, G.; Kucinskis, G.; Smits, J.; Kleperis, J.; Lusis, A.

2012-08-01

121

Strain accommodation and potential hysteresis of LiFePO 4 cathodes during lithium ion insertion\\/extraction  

Microsoft Academic Search

Equilibrium potential hysteresis of electrode materials refers to the phenomenon that discharge equilibrium potential is lower than charge equilibrium potential. It is induced by the strain accommodation energy of phase transformation. Taking LiFePO4 as an example, the equilibrium potential hysteresis and accommodation energy of two LiFePO4 with different particle sizes were characterized using galvanostatic intermittent titration technique (GITT), cyclic voltammetry

Yujie Zhu; Chunsheng Wang

2011-01-01

122

Improving the electrochemical performance of LiFePO4/C by doping magnesium trisilicate  

NASA Astrophysics Data System (ADS)

This work studies the effect of doping with magnesium trisilicate for LiFePO4/C cathode materials by a solid-state method. The samples were synthesized by two-step processing. Firstly, it was heated at 360 °C for 10 hours and then was calcined at 700°C for 10 hours. All the annealing processing was carried out in argon atmosphere. The phase structure, morphology and element distribution of prepared samples were characterized by XRD and scanning electron microscope and energy dispersive spectrometer. The results show that Mg2+ and Si4+ co-doped LiFe0.99Mg0.01P0.985Si0.015O4/C cathode materials exhibit higher capacity and rate capability than the unsubstituted LiFePO4/C cathode. For example, LiFe0.99Mg0.01P0.985Si0.015O4/C exhibit discharge capacity of 146 mAh·g-1 compared to 140mAh·g-1 for unsubstituted LiFePO4/C at 0.5C. Especially, at 5C rate, the discharge capacity of LiFe0.99Mg0.01P0.985Si0.015O4/C was remarkably exceeded that of unsubstituted LiFePO4/C cathode materials. The better performances of the cathode were attributed to the increase of electronic conductivity and the improved migration of lithium ion.

Chen, Weiqiang; Zhao, Shixi; Ding, Hao; Li, Baohua; Nan, Cewen

2011-11-01

123

Thermal modeling of a cylindrical LiFePO 4\\/graphite lithium-ion battery  

Microsoft Academic Search

A lumped-parameter thermal model of a cylindrical LiFePO4\\/graphite lithium-ion battery is developed. Heat transfer coefficients and heat capacity are determined from simultaneous measurements of the surface temperature and the internal temperature of the battery while applying 2Hz current pulses of different magnitudes. For internal temperature measurements, a thermocouple is introduced into the battery under inert atmosphere. Heat transfer coefficients (thermal

Christophe Forgez; Dinh Vinh Do; Guy Friedrich; Mathieu Morcrette; Charles Delacourt

2010-01-01

124

Mössbauer study on LiFePO 4 cathode material for lithium ion batteries  

Microsoft Academic Search

Crystalline LiFePO4 has been synthesized using solid-state, spray pyrolysis, and wet chemical methods. The crystal parameters were obtained from\\u000a Rietveld’s refinement methods of the X-ray diffraction patterns. A detailed investigation of the Fe valency carried out using\\u000a Mssbauer spectroscopy at room temperature indicates that Fe is predominantly present in its bivalent state.

B. Hannoyer; A. A. M. Prince; M. Jean; R. S. Liu; G. X. Wang

2006-01-01

125

Research on high rate capabilities B-substituted LiFePO4.  

PubMed

LiFePO4 is currently recognized as one of the most promising electrode materials for large-scale application of lithium ion batteries. However, the limitation of rate capability is believed to be intrinsic to this family of compounds due to the existence of larger tetrahedral (PO4)3- unit and quasi-hexagonal close-packed oxygen array. This paper report here a systematic investigation of the enhancement of rate performance by partly substitution of light small triangle oxyanion, (BO3)3-, for the larger tetrahedral (PO4)3- units in LiFePO4. Cathode electrode materials LiFeB(x)P(1_x)O(4-delta), in which X = 0, 3, 6 and 9, mol%, were synthesized by solid-state method. The as-synthesized products were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Electrochemical Measurements. The results showed that 6 mol% of boron substitution had no effect on the structure of LiFePO4 material, but significantly improved its rate performance. The initial discharge capacity of the LiFeB0.06P0.94O(4-delta) sample was 145.62 mAh/g at 0.1 C, and the capacity retention ratios of 81% at 2 C and 76% at 5 C were obtained, demonstrating that a proper amount of boron substitution (lower than 6 mol%) could significantly improve the rate performance of LiFePO4 cathode material. PMID:23646677

Wang, Fu; Zhang, Yun; Chen, Chao

2013-02-01

126

PPy doped PEG conducting polymer films synthesized on LiFePO 4 particles  

Microsoft Academic Search

In this work, polyethyleneglycole (PEG) is introduced into polypyrrole (PPy) film coated on LiFePO4 powder particles to promote the properties of cathode material for lithium-ion batteries. The enhancement of the electrochemical activity by the substitution of a carbon with electrochemically active polymer is investigated. Films of the PPy doped with the PEG were prepared by the chemical oxidative polymerization of

Andrea Fedorková; Renáta Ori?áková; Andrej Ori?ák; Ivan Talian; Andreas Heile; Hans-Dieter Wiemhöfer; Dušan Kaniansky; Heinrich F. Arlinghaus

2010-01-01

127

Mesoscale phase distribution in single particles of LiFePO4 following lithium deintercalation  

PubMed Central

The chemical phase distribution in hydrothermally grown micrometric single crystals LiFePO4 following partial chemical delithiation was investigated. Full field and scanning X-ray microscopy were combined with X-ray absorption spectroscopy at the Fe K- and O K-edges, respectively, to produce maps with high chemical and spatial resolution. The resulting information was compared to morphological insight into the mechanics of the transformation by scanning transmission electron microscopy. This study revealed the interplay at the mesocale between microstructure and phase distribution during the redox process, as morphological defects were found to kinetically determine the progress of the reaction. Lithium deintercalation was also found to induce severe mechanical damage in the crystals, presumably due to the lattice mismatch between LiFePO4 and FePO4. Our results lead to the conclusion that rational design of intercalation-based electrode materials, such as LiFePO4, with optimized utilization and life requires the tailoring of particles that minimize kinetic barriers and mechanical strain. Coupling TXM-XANES with TEM can provide unique insight into the behavior of electrode materials during operation, at scales spanning from nanoparticles to ensembles and complex architectures.

Boesenberg, Ulrike; Meirer, Florian; Liu, Yijin; Shukla, Alpesh K.; Dell'Anna, Rossana; Tyliszczak, Tolek; Chen, Guoying; Andrews, Joy C.; Richardson, Thomas J.; Kostecki, Robert; Cabana, Jordi

2013-01-01

128

Comparison of LiMnPO4 made by Combustion and Hydrothermal Syntheses  

Microsoft Academic Search

Among the olivine-structured metal phosphate family, LiMnPO exhibits a high discharge potential (4V), which is still compatible with common electrolytes, making it interesting for use in the next generation of Li ion batteries. The extremely low electronic conductivity of this material severely limits its electrochemical performance, however. One strategy to overcome this limitation is to make LiMnPO nanoparticulate to decrease

Jiajun Chen; Marca M. Doeff; Ruigang Wang

2008-01-01

129

Comparative studies on C-coated and uncoated LiFePO 4 cycling at various rates and temperatures using synchrotron based in situ X-ray diffraction  

Microsoft Academic Search

The structural changes of LiFePO4 and C-coated LiFePO4 during charging at various C-rates and temperatures are investigated using synchrotron based in situ X-ray diffraction technique. The XRD patterns collected during cycling show the structural evidence of the positive effects of carbon coating on LiFePO4 for the electrochemical performance improvements at different temperatures, especially at low temperatures. At ?10°C, the C-coated

Ho Chul Shin; Kyung Wan Nam; Won Young Chang; Byung Won Cho; Won-Sub Yoon; Xiao-Qing Yang; Kyung Yoon Chung

2011-01-01

130

Porous LiFePO 4 \\/NiP Composite nanospheres as the cathode materials in rechargeable lithium-ion batteries  

Microsoft Academic Search

We report the synthesis of porous LiFePO4\\/NiP composite nanospheres and their application in rechargeable lithium-ion batteries. A simple one-step spraying technique\\u000a was developed to prepare LiFePO4\\/NiP composite nanospheres with an electrical conductivity 103–104 times that of bulk particles of LiFePO4. Electrochemical measurements show that LiFePO4 nanospheres with a uniform loading of 0.86 wt%–1.50 wt% NiP exhibit high discharge capacity, good

Chunsheng Li; Shaoyan Zhang; Fangyi Cheng; Weiqiang Ji; Jun Chen

2008-01-01

131

A new insight into the LiFePO 4 delithiation process  

Microsoft Academic Search

Raman and Fourier transform infrared measurements for LixM0.03Fe0.97PO4, M=Cr, Cu, Al, Ti were performed. The spectra for delithiated samples to a low content of lithium extraction are practically the same as those of LiFePO4. For a high content of lithium extraction, the spectra repeat that of FePO4. In the case of the Li0.11FePO4 oxide the spectra cannot be reproduced just

V. Lemos; S. Guerini; J. Mendes Filho; S. M. Lala; L. A. Montoro; J. M. Rosolen

2006-01-01

132

Physical and electrochemical properties of LiFePO 4/carbon composite synthesized at various pyrolysis periods  

NASA Astrophysics Data System (ADS)

Aluminum-doped lithium iron phosphate was synthesized with a modified sol-gel process. The sol-gel derived cathodes show much higher conductivity than those prepared by a solid-state method. The conductivity is 8 × 10 -2 S cm -1 for the Al-doped LiFePO 4/carbon composite powders synthesized at 850 °C for 2 h, as determined using AC impedance spectroscopy. The electrodes consisting of the Al-doped LiFePO 4/carbon composite powders were fabricated for the electrochemical characterization and showed a specific capacity of about 150 mAh g -1 at C/40 rate. Not only the conductivity of the crystal lattice but also the conductivity of the grain boundary is enhanced for the nano-sized Al-doped LiFePO 4/carbon composite powders.

Hsu, Kuei-Feng; Tsay, Sun-Yuan; Hwang, Bing-Joe

133

A chemically activated graphene-encapsulated LiFePO4 composite for high-performance lithium ion batteries  

NASA Astrophysics Data System (ADS)

A composite of modified graphene and LiFePO4 has been developed to improve the speed of charging-discharging and the cycling stability of lithium ion batteries using LiFePO4 as a cathode material. Chemically activated graphene (CA-graphene) has been successfully synthesized via activation by KOH. The as-prepared CA-graphene was mixed with LiFePO4 to prepare the composite. Microscopic observation and nitrogen sorption analysis have revealed the surface morphologies of CA-graphene and the CA-graphene/LiFePO4 composite. Electrochemical properties have also been investigated after assembling coin cells with the CA-graphene/LiFePO4 composite as a cathode active material. Interestingly, the CA-graphene/LiFePO4 composite has exhibited better electrochemical properties than the conventional graphene/LiFePO4 composite as well as bare LiFePO4, including exceptional speed of charging-discharging and excellent cycle stability. That is because the CA-graphene in the composite provides abundant porous channels for the diffusion of lithium ions. Moreover, it acts as a conducting network for easy charge transfer and as a divider, preventing the aggregation of LiFePO4 particles. Owing to these properties of CA-graphene, LiFePO4 could demonstrate enhanced and stably long-lasting electrochemical performance.A composite of modified graphene and LiFePO4 has been developed to improve the speed of charging-discharging and the cycling stability of lithium ion batteries using LiFePO4 as a cathode material. Chemically activated graphene (CA-graphene) has been successfully synthesized via activation by KOH. The as-prepared CA-graphene was mixed with LiFePO4 to prepare the composite. Microscopic observation and nitrogen sorption analysis have revealed the surface morphologies of CA-graphene and the CA-graphene/LiFePO4 composite. Electrochemical properties have also been investigated after assembling coin cells with the CA-graphene/LiFePO4 composite as a cathode active material. Interestingly, the CA-graphene/LiFePO4 composite has exhibited better electrochemical properties than the conventional graphene/LiFePO4 composite as well as bare LiFePO4, including exceptional speed of charging-discharging and excellent cycle stability. That is because the CA-graphene in the composite provides abundant porous channels for the diffusion of lithium ions. Moreover, it acts as a conducting network for easy charge transfer and as a divider, preventing the aggregation of LiFePO4 particles. Owing to these properties of CA-graphene, LiFePO4 could demonstrate enhanced and stably long-lasting electrochemical performance. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr02738d

Ha, Jeonghyun; Park, Seung-Keun; Yu, Seung-Ho; Jin, Aihua; Jang, Byungchul; Bong, Sungyool; Kim, In; Sung, Yung-Eun; Piao, Yuanzhe

2013-08-01

134

Synthesis, non-isothermal kinetic and thermodynamic studies of the formation of LiMnPO4 from NH4MnPO4·H2O precursor  

NASA Astrophysics Data System (ADS)

NH4MnPO4·H2O was successfully synthesized by precipitating method. The LiMnPO4 was successfully generated through solid state reaction between synthesized NH4MnPO4·H2O precursor and Li2CO3. The morphologies were observed to depend on the reaction temperatures. The thermal decomposition of NH4MnPO4·H2O and the formation process of LiMnPO4 were confirmed by TG/DTG/DTA, FTIR, AAS/AES, XRD and SEM methods. The average crystallite size of NH4MnPO4·H2O, Mn2P2O7 and LiMnPO4 were found to be around 51.2, 44.9 and 48.1 nm, respectively. The non-isothermal kinetic parameters (kinetic triplet: E?, A, g(?)) of the formation process of LiMnPO4 were evaluated from TG data by using Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose methods. The iterative methods of both equations were carried out to determine the exact values of E?. The Coats-Redfern equation and kinetic compensation effects were successfully applied to confirm the activation energy and the most probable mechanism functions of the formation of LiMnPO4. The thermodynamic functions (?H?, ?S?, ?G?) of the transition state complexes of the formation of LiMnPO4 were calculated from the kinetic parameters for the first time.

Sronsri, Chuchai; Noisong, Pittayagorn; Danvirutai, Chanaiporn

2014-06-01

135

Highly porous LiMnPO 4 in combination with an ionic liquid-based polymer gel electrolyte for lithium batteries  

Microsoft Academic Search

A porous well defined LiMnPO4 cathode material is synthesized by a sol-gel method. The electrochemical performance of the cathode material is evaluated in a cell with an ionic liquid-based polymer electrolyte (0.5M LITFSI in EMImTFSI) and a lithium metal electrode. The results are compared to a cell with a traditional organic carbonate-based electrolyte (1M LiPF6 in EC\\/DMC). The cell with

Jae-Kwang Kim; Cho-Rong Shin; Jou-Hyeon Ahn; Aleksandar Matic; Per Jacobsson

2011-01-01

136

Nuclear Magnetic Resonances and Mn-O-P-O-Mn Superexchange Linkages in Paramagnetic and Antiferromagnetic LiMnPO4  

Microsoft Academic Search

Nuclear magnetic resonances of P31 and Li7 have been observed in single crystals of LiMnPO4 in the antiferromagnetic and paramagnetic states as a function of orientation from 4.2-300°K. The resonances were found to be shifted from the predicted gammaH0 in a way that indicates the presence of unpaired electrons in 3s (and possibly 3p) orbitals of the phosphorus atoms separated

John M. Mays

1963-01-01

137

Thermal Stability and Phase Transformation of Electrochemically Charged\\/Discharged LiMnPO4 Cathode for Li-Ion Battery  

Microsoft Academic Search

Electrochemically active LiMnPO4 nanoplate at lithiated\\/delithiated state were subjected to thermal stability and phase transformation evaluate for safety as a cathode material for Li-ion battery. The phase transformation and oxygen evolution temperature on the delithiated MnPO4 were characterized using in-situ hot-stage X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), thermogravimetric - differential scanning calorimetry - mass spectroscopy (TGA-DSC-MS), transmission electron microscopy

Daiwon Choi; Jie Xiao; Young Joon Choi; John S. Hardy; M. Vijayakumar; M. S. Bhuvaneswari; Jun Liu; Wu Xu; Wei Wang; Zhenguo Yang; Gordon L. Graff; Jiguang Zhang

2011-01-01

138

Ultrafast laser microstructuring of LiFePO4 cathode material  

NASA Astrophysics Data System (ADS)

LiFePO4 is a very promising material to be used as positive electrode for future lithium-ion batteries. Nevertheless, a reduced rate capability at high discharging and charging currents is the main drawback. In this work, a 3D structure was made in LiFePO4 composite electrodes by applying ultrafast laser ablation. The change of the electrochemical properties in a lithium-ion half-cell due to laser structuring was studied in detail and will be discussed. The main challenging goal is to correlate cell properties such as capacity retention with laser parameters and laser generated microstructure. For microstructuring electrode materials an ultrafast as well as a ns fiber laser were used. The pulse duration was varied in the range from 350 fs to 200 ns. With ultrashort laser radiation, the ablation efficiency was increased. Electrochemical characterisations were performed. For this purpose, Swagelok® test cells with lithium metal as counter electrode were assembled. Main electrochemical parameters such as specific capacity and cycle stability were determined for the cells with structured and unstructured cathodes. It was shown that the rate capability for the cells with structured cathodes in comparison to cells with unstructured cathodes was significantly enhanced, especially for high charging and discharging rates.

Mangang, M.; Pröll, J.; Tarde, C.; Seifert, H. J.; Pfleging, W.

2014-03-01

139

Ab-initio Calculation of the XANES of Lithium Phosphates and LiFePO4  

NASA Astrophysics Data System (ADS)

Lithium iron phosphate has been regarded as a promising cathode material for the next generation lithium ion batteries due to its high specific capacity, superior thermal and cyclic stability [1]. In this study, the XANES (X-ray Absorption Near Edge Structure) spectra of lithium iron phosphate and lithium phosphates of various compositions at the Li K, P L3,2, Fe M3,2 and O K-edges have been simulated self-consistently using ab-initio calculations based on multiple scattering theory (the FEFF9 code) and DFT (Density Functional Theory, the Wien2k code). The lithium phosphates under investigation include LiFePO4, ?-Li3PO4, Li4P2O7 and LiPO3. The calculated spectra are compared to the experimental XANES recorded in total electron yield (TEY) and fluorescence yield (FLY). This work was carried out to assess the XANES of possible phases presented in LiFePO4 based Li ion battery applications [2].

Yiu, Y. M.; Yang, Songlan; Wang, Dongniu; Sun, Xueliang; Sham, T. K.

2013-04-01

140

LiFePO 4 safe Li-ion polymer batteries for clean environment  

NASA Astrophysics Data System (ADS)

The performance of natural graphite-fibers/PEO-based gel electrolyte/LiFePO 4 cells (7 mAh, 4 cm 2) is reported. The gel polymer electrolytes were produced by electron-beam irradiation and then soaked in a liquid electrolyte. The natural graphite-fiber composite anode in gel electrolyte containing 1.5 M LiFSI-EC/GBL (1:3) exhibited high reversible capacity (361 mAh g -1) and high Coulombic efficiency (92%). The LiFePO 4 cathode in the same gel polymer exhibited a reversible capacity of 161 mAh g -1 and 93% Coulombic efficiency. A 1.5 M solution of LiFSI in ethylene carbonate (EC)/?-butyrolactone (GBL) (1:3, v/v) mixed solvent is advantageous for use as the electrolyte in the laminated film bag because of its high flame point (135 °C), high boiling point (219 °C), low vapor pressure and high conductivity (10.2 mS cm -1 at 20 °C). The Li-ion gel polymer battery shows a very low capacity fade of 5% after 500 cycles and also has high-rate capability. The Li-ion gel polymer cell using LiFePO 4 cathodes is suitable for HEV applications.

Zaghib, K.; Charest, P.; Guerfi, A.; Shim, J.; Perrier, M.; Striebel, K.

141

Physical and electrochemical properties of LiFePO 4\\/carbon composite synthesized at various pyrolysis periods  

Microsoft Academic Search

Aluminum-doped lithium iron phosphate was synthesized with a modified sol–gel process. The sol–gel derived cathodes show much higher conductivity than those prepared by a solid-state method. The conductivity is 8×10?2Scm?1 for the Al-doped LiFePO4\\/carbon composite powders synthesized at 850°C for 2h, as determined using AC impedance spectroscopy. The electrodes consisting of the Al-doped LiFePO4\\/carbon composite powders were fabricated for the

Kuei-Feng Hsu; Sun-Yuan Tsay; Bing-Joe Hwang

2005-01-01

142

Effect of synthesis conditions on the properties of LiFePO 4 for secondary lithium batteries  

Microsoft Academic Search

LiFePO4 is one of the promising materials for cathode of secondary lithium batteries due to its high energy density, low cost, environmental friendliness and safety. However, LiFePO4 has very poor electronic conductivity (?10?9Scm?1) and Li-ion diffusion coefficient (?1.8×10?14cm2s?1) at room temperature. In an attempt to improve electrochemical properties, LiXFePO4 with various amounts of Li contents were investigated in this study.

Do-Kyun Kim; Hyun-Min Park; Su-Jin Jung; Yeon Uk Jeong; Joon-Hyung Lee; Jeong-Joo Kim

2006-01-01

143

Carbon nanotube-loaded electrospun LiFePO4/carbon composite nanofibers as stable and binder-free cathodes for rechargeable lithium-ion batteries.  

PubMed

LiFePO(4)/CNT/C composite nanofibers were synthesized by using a combination of electrospinning and sol-gel techniques. Polyacrylonitrile (PAN) was used as the electrospinning media and carbon source. Functionalized CNTs were used to increase the conductivity of the composite. LiFePO(4) precursor materials, PAN and functionalized CNTs were dissolved or dispersed in N,N-dimethylformamide separately and they were mixed before electrospinning. LiFePO(4) precursor/CNT/PAN composite nanofibers were then heat-treated to obtain LiFePO(4)/CNT/C composite nanofibers. Fourier transform infrared spectroscopy measurements were done to demonstrate the functionalization of CNTs. The structure of LiFePO(4)/CNT/C composite nanofibers was determined by X-ray diffraction analysis. The surface morphology and microstructure of LiFePO(4)/CNT/C composite nanofibers were characterized using scanning electron microscopy and transmission electron microscopy. Electrochemical performance of LiFePO(4)/CNT/C composite nanofibers was evaluated in coin-type cells. Functionalized CNTs were found to be well-dispersed in the carbonaceous matrix and increased the electrochemical performance of the composite nanofibers. As a result, cells using LiFePO(4)/CNT/C composite nanofibers have good performance, in terms of large capacity, extended cycle life, and good rate capability. PMID:22301674

Toprakci, Ozan; Toprakci, Hatice A K; Ji, Liwen; Xu, Guanjie; Lin, Zhan; Zhang, Xiangwu

2012-03-01

144

Tailored Surface Structure of LiFePO4/C Nanofibers by Phosphidation and Their Electrochemical Superiority for Lithium Rechargeable Batteries.  

PubMed

We offer a brand new strategy for enhancing Li ion transport at the surface of LiFePO4/C nanofibers through noble Li ion conducting pathways built along reduced carbon webs by phosphorus. Pristine LiFePO4/C nanofibers composed of 1-dimensional (1D) LiFePO4 nanofibers with thick carbon coating layers on the surfaces of the nanofibers were prepared by the electrospinning technique. These dense and thick carbon layers prevented not only electrolyte penetration into the inner LiFePO4 nanofibers but also facile Li ion transport at the electrode/electrolyte interface. In contrast, the existing strong interactions between the carbon and oxygen atoms on the surface of the pristine LiFePO4/C nanofibers were weakened or partly broken by the adhesion of phosphorus, thereby improving Li ion migration through the thick carbon layers on the surfaces of the LiFePO4 nanofibers. As a result, the phosphidated LiFePO4/C nanofibers have a higher initial discharge capacity and a greatly improved rate capability when compared with pristine LiFePO4/C nanofibers. Our findings of high Li ion transport induced by phosphidation can be widely applied to other carbon-coated electrode materials. PMID:24786736

Lee, Yoon Cheol; Han, Dong-Wook; Park, Mihui; Jo, Mi Ru; Kang, Seung Ho; Lee, Ju Kyung; Kang, Yong-Mook

2014-06-25

145

Hole polaron formation and migration in olivine phosphate materials  

NASA Astrophysics Data System (ADS)

By combining first-principles calculations and experimental x-ray photoemission (XPS) spectroscopy measurements, we investigate the electronic structure of potential Li-ion battery cathode materials LiMPO4 (M=Mn, Fe, Co, Ni) to uncover the underlying mechanisms that determine small hole polaron formation and migration. We show that small hole polaron formation depends on features in the electronic structure near the valence-band maximum and that, calculationally, these features depend on the methodology chosen for dealing with the correlated nature of the transition-metal d-derived states in these systems. Comparison with experiment reveals that a hybrid functional approach is superior to GGA+U in correctly reproducing the XPS spectra. Using this approach, we find that LiNiPO4 cannot support small hole polarons, but that the other three compounds can. The migration barrier is determined mainly by the strong- or weak-bonding nature of the states at the top of the valence band, resulting in a substantially higher barrier for LiMnPO4 than for LiCoPO4 or LiFePO4.

Johannes, M. D.; Hoang, Khang; Allen, J. L.; Gaskell, K.

2012-03-01

146

Effect of surfactants on the electrochemical behavior of LiFePO4 cathode material for lithium ion batteries  

NASA Astrophysics Data System (ADS)

The application of lithium iron phosphate as positive electrode material for lithium ion batteries has been challenged by its poor electronic conductivity. To improve its conductivity and electrochemical performance, we have synthesized LiFePO4/C composite cathode materials by sol gel technique using long chain fatty acids, such as, lauric, myristic, and oleic acids, as surfactants for carbon coating. The phase purity of the three LiFePO4/C composites was confirmed by X-ray diffraction. The Raman spectroscopy, scanning electron microscopy and transmission electron microscopy measurements show that the surfactants coat the LiFePO4 particles with carbon with varying degree of uniformity depending on the surfactant used. The sample prepared in presence of lauric acid shows smaller particle size and the lowest charge transfer resistance, higher Li-ion diffusion coefficient, higher discharge capacity (?155 mAh g-1 at C/3 rate), better rate capability and cyclic stability compared to the other two samples. We found the smaller particle size, uniformity of carbon coating, reduced agglomeration, and a lower amount of Fe3+ impurity phase in the samples to be major contributing factors for better electrochemical properties in the LiFePO4/C cathode material.

Bazzi, K.; Mandal, B. P.; Nazri, M.; Naik, V. M.; Garg, V. K.; Oliveira, A. C.; Vaishnava, P. P.; Nazri, G. A.; Naik, R.

2014-11-01

147

Li ion diffusion mechanisms in LiFePO4: an ab initio molecular dynamics study.  

PubMed

The mechanisms for thermal (self) diffusion of Li ions in fully lithiated LiFePO(4) have been investigated with spin polarized ab initio molecular dynamics calculations. The effect of electron correlation is taken into account with the GGA+U formalism. It was found that Li ion diffusion is not a continuous process but through a series of jumps from one site to another. A dominant process is the hopping between neighboring Li sites around the PO(4) groups, which results in a zigzag pathway along the crystallographic b-axis. This observation is in agreement with a recent neutron diffraction experiment. A second process involves the collaborative movements of the Fe ions leading to the formation of antisite defects and promotes Li diffusion across the Li ion channels. The finding of the second mechanism demonstrates the benefit of ab initio molecular dynamics simulation in sampling diffusion pathways that may not be anticipated. PMID:21932862

Yang, Jianjun; Tse, John S

2011-11-17

148

The hydrothermal synthesis and characterization of olivines and related compounds for electrochemical applications  

Microsoft Academic Search

A number of cathodes are being considered for the next generation of lithium ion batteries to replace the expensive LiCoO2 presently used. Besides the layered oxides, such as LiNiyMnyCo1?2yO2, a leading candidate is lithium iron phosphate with the olivine structure. Although this material is inherently low cost, a manufacturing process that produces electrochemically-active LiFePO4 at a low cost is also

Jiajun Chen; Michael J. Vacchio; Shijun Wang; Natalya Chernova; Peter Y. Zavalij; M. Stanley Whittingham

2008-01-01

149

Enhanced electrochemical performance of nano-sized LiFePO 4\\/C synthesized by an ultrasonic-assisted co-precipitation method  

Microsoft Academic Search

A simple and effective method, the ultrasonic-assisted co-precipitation method, was employed to synthesize nano-sized LiFePO4\\/C. A glucose solution was used as the carbon source to produce in situ carbon to improve the conductivity of LiFePO4. Ultrasonic irradiation was adopted to control the size and homogenize the LiFePO4\\/C particles. The sample was characterized by X-ray powder diffraction, field-emission scanning electron microscopy

Youyong Liu; Chuanbao Cao

2010-01-01

150

Improving the electrochemical activity of LiMnPO 4 via Mn-site co-substitution with Fe and Mg  

Microsoft Academic Search

LiMnPO4, LiMn0.9Fe0.1PO4 and LiMn0.9Fe0.05Mg0.05PO4 were synthesized by a solid-state reaction route. All samples are single phase with a similar morphology, but the cation substitution results in a crystal lattice shrink because of the smaller ionic radii of Mg2+ and Fe2+. The Fe and Mg co-substitution leads to a significantly increased reversible capacity due to the enhanced electrochemical kinetics. The LiMn0.9Fe0.05Mg0.05PO4

Chenglin Hu; Huihua Yi; Haisheng Fang; Bin Yang; Yaochun Yao; Wenhui Ma; Yongnian Dai

2010-01-01

151

Thermal Stability and Phase Transformation of Electrochemically Charged/Discharged LiMnPO4 Cathode for Li-Ion Battery  

SciTech Connect

Electrochemically active LiMnPO4 nanoplate at lithiated/delithiated state were subjected to thermal stability and phase transformation evaluate for safety as a cathode material for Li-ion battery. The phase transformation and oxygen evolution temperature on the delithiated MnPO4 were characterized using in-situ hot-stage X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), thermogravimetric - differential scanning calorimetry - mass spectroscopy (TGA-DSC-MS), transmission electron microscopy and scanning electron microscopy (SEM) - energy dispersive X-ray analysis (EDAX).

Choi, Daiwon; Xiao, Jie; Choi, Young Joon; Hardy, John S.; Vijayakumar, M.; Bhuvaneswari, M. S.; Liu, Jun; Xu, Wu; Wang, Wei; Yang, Zhenguo; Graff, Gordon L.; Zhang, Jiguang

2011-11-01

152

A novel synthetic route for LiFePO 4\\/C cathode materials by addition of starch for lithium-ion batteries  

Microsoft Academic Search

LiFePO4\\/Carbon composite cathode material was prepared using starch as carbon source by spray-pelleting and subsequent pyrolysis in N2. The samples were characterized by XRD, SEM, Raman, and their electrochemical performance was investigated in terms of cycling behavior. There has a special micro-morphology via the process, which is favorable to electrochemical properties. The discharge capacity of the LiFePO4\\/C composite was 170mAhg?1,

Shao Hua Luo; Zi Long Tang; Jun Biao Lu; Zhong Tai Zhang

2007-01-01

153

The low cost synthesis of nanoparticles LiFePO 4\\/C composite for lithium rechargeable batteries  

Microsoft Academic Search

LiFePO4\\/C nanoparticles were prepared using raw Fe2O3 and Fe materials by rheological phase reaction under nitrogen atmosphere. Thermogravimetric analysis (TGA) was employed to analyze the precursor. The effect of the sintering temperature on its structure was investigated by X-ray diffraction (XRD). The chemical composition, surface morphology and valance states of the as-prepared product sintered at 700 °C has been characterized by

Haowen Liu; Dingguo Tang

2008-01-01

154

High performance LiFePO 4\\/C cathode for lithium ion battery prepared under vacuum conditions  

Microsoft Academic Search

LiFePO4\\/C with smaller particle size (0.3–0.6 ?m) was synthesized via a two-step vacuum sintering method. X-ray diffraction and scanning electron microscopy were used to detect the phases presented in the composites and observe sample morphology. In addition, AC electrochemical impedance spectroscopy, cyclic voltammetry, along with constant current discharge\\/charge tests, were used to characterize the electrochemical properties of the composites. It was

Lulu Zhang; Gang Peng; Xuelin Yang; Pengchang Zhang

2010-01-01

155

Dynamic electric behavior and open-circuit-voltage modeling of LiFePO 4-based lithium ion secondary batteries  

Microsoft Academic Search

Accurate battery modeling is one of the key factors in battery system design process and operation as well. Therefore, the knowledge of the distinct electric characteristics of the battery cells is mandatory. This work gives insight to the electric characteristics of lithium ion batteries (Li-ion) comprising LiFePO4-based cathode active materials with emphasis on their specific open-circuit-voltage (OCV) characteristics including hysteresis

Michael A. Roscher; Dirk Uwe Sauer

2011-01-01

156

Excellent Temperature Performance of Spherical LiFePO4/C Composites Modified with Composite Carbon and Metal Oxides  

PubMed Central

Nanosized spherical LiFePO4/C composite was synthesized from nanosized spherical FePO4·2H2O, Li2C2O4, aluminum oxide, titanium oxide, oxalic acid, and sucrose by binary sintering process. The phases and morphologies of LiFePO4/C were characterized using SEM, TEM, CV, EIS, EDS, and EDX as well as charging and discharging measurements. The results showed that the as-prepared LiFePO4/C composite with good conductive webs from nanosized spherical FePO4·2H2O exhibits excellent electrochemical performances, delivering an initial discharge capacity of 161.7?mAh·g?1 at a 0.1?C rate, 152.4?mAh·g?1 at a 1?C rate and 131.7?mAh·g?1 at a 5?C rate, and the capacity retention of 99.1%, 98.7%, and 95.8%, respectively, after 50 cycles. Meanwhile, the high and low temperature performance is excellent for 18650 battery, maintaining capacity retention of 101.7%, 95.0%, 88.3%, and 79.3% at 55°C, 0°C, ?10°C, and ?20°C by comparison withthat of room temperature (25°C) at the 0.5 C rate over a voltage range of 2.2?V to 3.6?V, respectively.

Zhang, Bao; Zeng, Tao; Zhang, Jiafeng; Peng, Chunli; Zheng, Junchao; Chen, Guomin

2014-01-01

157

Carbon-coated LiFePO4-porous carbon composites as cathode materials for lithium ion batteries  

NASA Astrophysics Data System (ADS)

This work introduces a facile strategy for the synthesis of carbon-coated LiFePO4-porous carbon (C-LiFePO4-PC) composites as a cathode material for lithium ion batteries. The LiFePO4 particles obtained are about 200 nm in size and homogeneously dispersed in porous carbon matrix. These particles are further coated with the carbon layers pyrolyzed from sucrose. The C-LiFePO4-PC composites display a high initial discharge capacity of 152.3 mA h g-1 at 0.1 C, good cycling stability, as well as excellent rate capability (112 mA h g-1 at 5 C). The likely contributing factors to the excellent electrochemical performance of the C-LiFePO4-PC composites could be related to the combined effects of enhancement of conductivity by the porous carbon matrix and the carbon coating layers. It is believed that further carbon coating is a facile and effective way to improve the electrochemical performance of LiFePO4-PC.

Ni, Haifang; Liu, Jinkun; Fan, Li-Zhen

2013-02-01

158

A synthesis of LiFePO4 starting from FePO4 under reducing atmosphere  

NASA Astrophysics Data System (ADS)

A fast and easy way to produce LiFePO4 starting from FePO4, used as iron and phosphorus source, is proposed. 5% hydrogen is employed as a reducing agent and various compounds containing lithium as lithiation agents. The selected lithiation agents included: LiCl, CH3COOLi, LiOH, Li2S, LiH, and Li2CO3. Solid state synthesis is used for the LiFePO4 preparation and the so obtained materials are structurally characterized by XRD. The materials are used to fabricate composite electrode and their specific capacity is evaluated by low rate galvanostatic charge/discharge cycles (C/10 rate). Among the various lithium salts, the acetate give rise to the LiFePO4 with the best electrochemical performance. The morphology of this material is further investigated by SEM microscopy and the specific capacity is evaluated as a function of the discharge rate and the cycle number.

Prosini, Pier Paolo; Cento, Cinzia; Masci, Amedeo; Carewska, Maria; Gislon, Paola

2014-06-01

159

In Situ Observation of Random Solid Solution Zone in LiFePO4 Electrode.  

PubMed

Nanostructured LiFePO4 (LFP) electrodes have attracted great interest in the Li-ion battery field. Recently there have been debates on the presence and role of metastable phases during lithiation/delithiation, originating from the apparent high rate capability of LFP batteries despite poor electronic/ionic conductivities of bulk LFP and FePO4 (FP) phases. Here we report a potentiostatic in situ transmission electron microscopy (TEM) study of LFP electrode kinetics during delithiation. Using in situ high-resolution TEM, a Li-sublattice disordered solid solution zone (SSZ) is observed to form quickly and reach 10-25 nm × 20-40 nm in size, different from the sharp LFP|FP interface observed under other conditions. This 20 nm scale SSZ is quite stable and persists for hundreds of seconds at room temperature during our experiments. In contrast to the nanoscopically sharp LFP|FP interface, the wider SSZ seen here contains no dislocations, so reduced fatigue and enhanced cycle life can be expected along with enhanced rate capability. Our findings suggest that the disordered SSZ could dominate phase transformation behavior at nonequilibrium condition when high current/voltage is applied; for larger particles, the SSZ could still be important as it provides out-of-equilibrium but atomically wide avenues for Li(+)/e(-) transport. PMID:24823479

Niu, Junjie; Kushima, Akihiro; Qian, Xiaofeng; Qi, Liang; Xiang, Kai; Chiang, Yet-Ming; Li, Ju

2014-07-01

160

A molecular dynamics simulation study of LiFePO4/electrolyte interfaces: structure and Li+ transport in carbonate and ionic liquid electrolytes.  

PubMed

We have performed atomistic molecular dynamics (MD) simulations of the (010) surface of LiFePO(4) in contact with an organic liquid electrolyte (OLE), ethylene carbonate : dimethyl carbonate (3 : 7) with approximately 1 mol kg(-1) LiPF(6), and an ionic liquid-based electrolyte (ILE), 1-ethyl 3-methyl-imidazolium: bis(fluorosulfonyl)imide (EMIM(+) : FSI(-)) with approximately 1 mol kg(-1) LiFSI. Surface-induced structure that extends about 1 nm from the LiFePO(4) surface was observed in both electrolytes. The electrostatic potential at the LiFePO(4) surface was found to be negative relative to the bulk electrolyte reflecting an excess of negative charge from the electrolyte coordinating surface Li(+). In the ILE system negative surface charge is partially offset by a high density of EMIM(+) cations coordinating surface oxygen. The electrostatic potential exhibits a (positive) maximum about 3 A from the LiFePO(4) surface which, when combined with the reduced ability of the highly structured electrolytes to solvate Li(+) cations, results in a free energy barrier of almost 4 kcal mol(-1) for penetration of the interfacial electrolyte layer by Li(+). The resistance for bringing Li(+) from the bulk electrolyte to the LiFePO(4) surface through this interfacial barrier was found to be small for both the OLE and ILE. However, we find that the ability of EMIM(+) cations to donate positive charge to LiFePO(4)/electrolyte interface may result in a significant decrease in the concentration of Li(+) at the surface and a corresponding increase in impedance to Li(+) intercalation into LiFePO(4), particularly at lower temperatures. PMID:19851568

Smith, Grant D; Borodin, Oleg; Russo, Salvy P; Rees, Robert J; Hollenkamp, Anthony F

2009-11-14

161

Optimization of multicomponent aqueous suspensions of lithium iron phosphate (LiFePO4) nanoparticles and carbon black for lithium-ion battery cathodes.  

PubMed

Addition of polyethyleneimine (PEI) to aqueous LiFePO4 nanoparticle suspensions improves stability and reduces agglomerate size, which is beneficial to lithium-ion battery cathode manufacturing. This research examines the effect of both PEI concentration and molecular weight (MW) on dispersing LiFePO4 and Super P C45 in multicomponent aqueous suspensions. It is demonstrated that the optimal conditions for obtaining stable suspensions with minimal agglomerate size are 1.5 wt% PEI with MW=2000 g mol(-1) and 5.0 wt% PEI with MW=10,000 g mol(-1) for LiFePO4 and Super P C45, respectively. The mixing sequence also affects rheological properties of these suspensions. It is found that dispersing the LiFePO4 and Super P C45 separately yielded suspensions with superior properties (Newtonian rheological behavior, smaller agglomerate size, improved settling, etc.). In particular, dispersing the LiFePO4 prior to the Super P C45 when making the final multicomponent suspension is found to be beneficial, which was evidenced by higher half-cell discharge capacity. PMID:23764234

Li, Jianlin; Armstrong, Beth L; Daniel, Claus; Kiggans, Jim; Wood, David L

2013-09-01

162

Monodisperse porous LiFePO4/C microspheres derived by microwave-assisted hydrothermal process combined with carbothermal reduction for high power lithium-ion batteries  

NASA Astrophysics Data System (ADS)

A microwave-assisted hydrothermal approach combined with carbothermal reduction has been developed to synthesize monodisperse porous LiFePO4/C microspheres, which possess the diameter range of 1.0-1.5 ?m, high tap density of ?1.3 g cm-3, and mesoporous characteristic with Brunauer-Emmett-Teller (BET) surface area of 30.6 m2 g-1. The obtained microspheres show meatball-like morphology aggregated by the carbon-coated LiFePO4 nanoparticles. The electrochemical impedance spectra (EIS) results indicate that carbon coating can effectively enhance both of the electronic and ionic conductivities for LiFePO4/C microspheres. The Li-ion diffusion coefficient of the LiFePO4/C microspheres calculated from the cyclic voltammetry (CV) curves is ?6.25 × 10-9 cm2 s-1. The electrochemical performance can achieve about 100 and 90 mAh g-1 at 5C and 10C charge/discharge rates, respectively. As cathode material, the as-prepared LiFePO4/C microspheres show excellent rate capability and cycle stability, promising for high power lithium-ion batteries.

Chen, Rongrong; Wu, Yixiong; Kong, Xiang Yang

163

Effect of complexing agents on the electrochemical performance of LiFePO4/C prepared by sol-gel method  

NASA Astrophysics Data System (ADS)

LiFePO4/C is synthesized via sol-gel method using Fe3+ as iron sources and different complexing agents, followed by sintering at high temperature for crystallization. The amount of carbon in these composites is less than 6.8 wt.%, and the X-ray diffraction experiment confirms that all samples are pure single phase indexed with the orthorhombic Pnma space group. The particle size of the LiFePO4/C synthesized by acetic acid as a complexing agent is very fine with a size of 200 nm. The electrochemical performance of this material, including reversible capacity, cycle number, and charge-discharge characteristics, is better than those of LiFePO4/C synthesized by other complexing agents. The cell of this sample can deliver a discharge capacity of 161.1 mAh g-1 at the first cycle. After 30 cycles, the capacity decreases to 157.5 mAh g-1, and the capacity fading rate is 2.2%. The mechanism is studied to explain the effect of a complexing agent on the synthesis of LiFePO4/C by sol-gel method. The results show that the complexing agent with a low stability constant may be proper for the synthetic process of LiFePO4/C via sol-gel method.

Yang, Rong; Kang, Erwei; Jiang, Bailing; Ahn, Jou-Hyeon

2012-01-01

164

Impact of carbon structure and morphology on the electrochemical performance of LiFePO4/C composites  

SciTech Connect

The electrochemical performance of LiFePO4/C composites in lithium cells is closely correlated to pressed pellet conductivities measured by AC impedance methods. These composite conductivities are a strong function not only of the amount of carbon but of its structure and distribution. Ideally, the amount of carbon in composites should be minimal (less than about 2 wtpercent) so as not to decrease the energy density unduly. This is particularly important for plug-in hybrid electric vehicle applications (PHEVs) where both high power and moderate energy density are required. Optimization of the carbon structure, particularly the sp2/sp3 and disordered/graphene (D/G) ratios, improves the electronic conductivity while minimizing the carbon amount. Manipulation of the carbon structure can be achieved via the use of synthetic additives including ironcontaining graphitization catalysts. Additionally, combustion synthesis techniques allow co-synthesis of LiFePO4 and carbon fibers or nanotubes, which can act as"nanowires" for the conduction of current during cell operation.

Doeff, Marca M.; Doeff, Marca M.; Wilcox, James D.; Yu, Rong; Aumentado, Albert; Marcinek, Marek; Kostecki, Robert

2007-09-19

165

Aluminium-doped LiFePO4 single crystals. Part II. Ionic conductivity, diffusivity and defect model.  

PubMed

We report on lithium ion conductivity and diffusivity along major crystallographic directions of Al-doped LiFePO4 single crystals. Impedance spectroscopy as well as galvanostatic polarization measurements have been carried out on the electronically blocking symmetric cell LiAl/LiI/LiFe(Al)PO4/LiI/LiAl. Neither ionic conductivity nor lithium diffusivity show anisotropy in the bc planes within the experimental error, but much lower values in the a-direction. Similar features were observed earlier by us for the pure single-crystal and the Si-doped single crystal. On Al-doping the ionic conductivity has increased while the electronic conductivity has decreased compared to undoped LiFePO4. Not only this donor doping effect but also the temperature dependence of ionic conductivity and of lithium-diffusivity are successfully interpreted in terms of lithium vacancies, holes and associates in the framework of a detailed defect chemical analysis. Ion-electron as well as ion-ion associates play a significant role in this system. PMID:18548158

Amin, Ruhul; Lin, Chengtian; Maier, Joachim

2008-06-28

166

Impedance Spectroscopy Studies of Nano-Crystalline LiFePO4 Cathode Synthesized by Hydrothermal Method  

NASA Astrophysics Data System (ADS)

LiFePO4 has become of great interest as storage cathodes for rechargeable lithium batteries because of their high energy density, low raw materials cost, environmental friendliness, high thermal stability. In the present investigation, lithium iron phosphate (LiFePO4) cathode material has been prepared by using hydrothermal synthesis. The structure of the sample has been studies by using X-ray diffraction. The XRD spectrum exhibited different characteristic peaks along with (311) predominant orientation corresponding to an orthorhombic crystal structure with Pnma space group. Electrical and dielectric properties were studied over a frequency range of 1 Hz - 1 MHz at different temperatures. The electrical conductivity was found to be increased with increasing temperature following Arrhenius relation with an estimated activation energy of 0.44 eV. The dielectric properties were analyzed in the framework of complex dielectric permittivity and complex electric modulus formalisms. The evolution of the complex permittivity as a function of frequency and temperature was investigated. Several important parameters such as activation energy, ionic hopping frequency, carrier concentration, ionic mobility and diffusion coefficient etc, were determined.

Rosaiah, P.; Hussain, O. M.

167

Near-field Nanoscopy and Spectroscopy of Phase Coexistence in LiFePO4 Electrode Microcrystals  

NASA Astrophysics Data System (ADS)

Due to instrumental limitations, the microscopic description of lithiation and delithiation processes in low-cost LiFePO4 electrodes has remained uncertain and subject to controversy. Using infrared near-field imaging, we present evidence for a novel coexistence of phases within single LiFePO4 microcrystals. First-principles calculations of the phonon response of lithiated and delithiated end-phases are compared with broadband nano-FTIR (Fourier transform infrared) spectroscopy data to reveal the mid-infrared vibrational signature of lithiation. By resolving this signature at the nano-scale, we observe a propagation of phase boundaries within these crystals over the course of chemical delithiation. In addition, by comparing theoretical modeling with spatially resolved nano-FTIR spectra measured across a single crystal at partial delithiation, we assemble a tomographic view of phases distributed hundreds nanometers beneath the crystal surface. These experiments set the stage for quantitative nano-spectroscopy of new composite electrode materials, assisting in the rational design of next-generation electrical energy storage systems.

Lucas, Ivan T.; McLeod, Alexander; Syzdek, Jaroslaw S.; Middlemiss, Derek S.; Kostecki, Robert; Basov, D. N.

2013-03-01

168

Sequential Monte Carlo filter for state estimation of LiFePO4 batteries based on an online updated model  

NASA Astrophysics Data System (ADS)

Battery state monitoring is one of the key techniques in battery management systems e.g. in electric vehicles. An accurate estimation can help to improve the system performance and to prolong the battery remaining useful life. Main challenges for the state estimation for LiFePO4 batteries are the flat characteristic of open-circuit-voltage over battery state of charge (SOC) and the existence of hysteresis phenomena. Classical estimation approaches like Kalman filtering show limitations to handle nonlinear and non-Gaussian error distribution problems. In addition, uncertainties in the battery model parameters must be taken into account to describe the battery degradation. In this paper, a novel model-based method combining a Sequential Monte Carlo filter with adaptive control to determine the cell SOC and its electric impedance is presented. The applicability of this dual estimator is verified using measurement data acquired from a commercial LiFePO4 cell. Due to a better handling of the hysteresis problem, results show the benefits of the proposed method against the estimation with an Extended Kalman filter.

Li, Jiahao; Klee Barillas, Joaquin; Guenther, Clemens; Danzer, Michael A.

169

Structure and electrochemical characteristics of LiFePO4 cathode materials for rechargeable Li-Ion batteries  

NASA Astrophysics Data System (ADS)

Complex investigations of cathode materials for rechargeable lithium-ion batteries have been carried out using the following techniques: scanning electron microscopy, microanalysis, extended X-ray absorption fine structure (EXAFS) spectroscopy, Mössbauer spectroscopy, and porosimetry. Investigations have been performed on samples prepared according to the original technology at the St. Petersburg State Institute of Technology (Technical University) (SPbSTI (TU)) and on four commercial cathode materials. It has been established that there is a correlation between the nanostructured morphology of the cathode materials, their chemical composition, and electrochemical capacity. It has been found that the internal resistance of the LiFePO4 cathode material is linearly dependent on the diffusion coefficient of lithium ions. The valence state and local coordination of Fe ions have been studied using the 57Fe Mössbauer effect. It has been shown that more than 90% of the iron ions are in the valence state Fe2+. Based on the data available in the literature on the methods of synthesizing LiFePO4 and data on the diagnosis of the studied samples, conclusions have been drawn about a modification of the synthesis for producing high-quality cathode materials for Li-ion batteries.

Kamzin, A. S.; Bobyl', A. V.; Ershenko, E. M.; Terukov, E. I.; Agafonov, D. V.; Kudryavtsev, E. N.

2013-07-01

170

Enhanced electrochemical properties of LiMnPO 4 \\/C via Li-site substitution with Mg  

Microsoft Academic Search

Li0.94Mg0.03MnPO4\\/C composite cathode materials for lithium ion battery with different carbon contents are synthesized by sol–gel method followed\\u000a by heat treatment in the air. Environmental scanning electron microscopy measurements show that both firing temperature and\\u000a carbon content affect the morphology of the end products. X-ray powder diffraction analysis indicates that the samples are\\u000a olivine-structured. The galvanostatic charge–discharge results show that

Yurong Zhang; Yanyan Zhao

2011-01-01

171

Interphase Evolution at Two Promising Electrode Materials for Li-Ion Batteries: LiFePO4 and LiNi1/2 Mn1/2 O2.  

PubMed

The present review reports the characterization and control of interfacial processes occurring on olivine LiFePO4 and layered LiNi1/2 Mn1/2 O2 , standing here as model compounds, during storage and electrochemical cycling. The formation and evolution of the interphase created by decomposition of the electrolyte is investigated by using spectroscopic tools such as magic-angle-spinning nuclear magnetic resonance ((7) Li, (19) F and (31) P) and electron energy loss spectroscopy, in parallel to X-ray photoelectron spectroscopy, to quantitatively describe the interphase and unravel its architecture. The influence of the pristine surface chemistry of the active material is carefully examined. The importance of the chemical history of the surface of the electrode material before any electrochemical cycling and the strong correlation between interface phenomena, the formation/evolution of an interphase, and the electrochemical behavior appear clearly from the use of these combined characterization probes. This approach allows identifying interface aging and failure mechanisms. Different types of surface modifications are then investigated, such as intrinsic modifications upon aging in air or methods based on the use of additives in the electrolyte or carbon coatings on the surface of the active materials. In each case, the species detected on the surface of the materials during storage and cycling are correlated with the electrochemical performance of the modified positive electrodes. PMID:24789623

Dupré, Nicolas; Cuisinier, Marine; Martin, Jean-Frederic; Guyomard, Dominique

2014-07-21

172

A dynamic equivalent circuit model of LiFePO4 cathode material for lithium ion batteries on hybrid electric vehicles  

Microsoft Academic Search

With excellent performance, LiFePO4 cathode material for lithium ion batteries attracts more and more attention on HEVs. In this paper, the dynamic characteristics of the batteries are investigated over different current profiles. A dynamic equivalent circuit model is proposed to describe the dynamic characteristics of the batteries. Simulation results over different tests show the dynamic equivalent circuit model can represent

Liao Chenglin; Li Huiju; Wang Lifang

2009-01-01

173

Metal Foam as Positive Electrode Current Collector for LiFePO4-Based Li-Ion Battery  

NASA Astrophysics Data System (ADS)

In order to improve the kinetic performance of LiFePO4-based Li-ion batteries, three dimensional metal foams were used as positive current collector. In the case of conventional Ni foam, the organic electrolyte of the cell was decomposed with the ionization of Ni during charge and discharge. The low tolerance of Ni was solved by using NiCrAl foam which was manufactured by alloying NiCrAl powder with Ni foam. From the electrochemical analysis, it shows that the kinetic performance of the cell by using a three dimensional NiCrAl foam was much superior to that in the case of conventional foil type.

Yang, Gui Fu; Song, Jae Sun; Kim, Hyung Yoon; Joo, Seung Ki

2013-10-01

174

The effect of Cr doping on Li ion diffusion in LiFePO4 from first principles investigations and Monte Carlo simulations  

NASA Astrophysics Data System (ADS)

Using the adiabatic trajectory method, the migration energy barriers for the migration of Li ions and Cr ions along the one-dimensional diffusion pathway in pure and Cr doped LiFePO4 are obtained from first principles calculations. The results show that while Li ions can diffuse along the diffusion pathway easily, Cr ions do not easily diffuse away from their initial positions. This means that the heavy Cr ions will block the one-dimensional diffusion pathway of the material. Monte Carlo simulations are performed to evaluate the influences of the blocking behaviours on the electrochemical performance of LiFePO4 cathode material for Li ion secondary batteries. The results show that the evaluated capacity is highly sensitive to the amount of the dopant, the size of the super-cell being used for simulation (particle size of the powder cathode material) and the Monte Carlo steps for statistics (charge-discharge current density).

Ouyang, C. Y.; Shi, S. Q.; Wang, Z. X.; Li, H.; Huang, X. J.; Chen, L. Q.

2004-04-01

175

Template-free reverse micelle process for the synthesis of a rod-like LiFePO 4\\/C composite cathode material for lithium batteries  

Microsoft Academic Search

The synthesis of rod-like LiFePO4\\/C cathodes using template-free reverse micelle process is reported for high performance lithium batteries. We have demonstrated that the size of the primary particles could be controlled based on sintering temperature and sintering time and size of the large aggregates is adjustable based on the carbon content of the sample. Thermogravimetry and differential thermal analysis have

Bing-Joe Hwang; Kuei-Feng Hsu; Shao-Kang Hu; Ming-Yao Cheng; Tse-Chuan Chou; Sun-Yuan Tsay; Raman Santhanam

2009-01-01

176

Fine-particle lithium iron phosphate LiFePO 4 synthesized by a new low-cost aqueous precipitation technique  

Microsoft Academic Search

Phase pure, homogeneous, and well-crystallized lithium iron phosphate LiFePO4 was synthesized by aqueous co-precipitation of an Fe(II) precursor material and succeeding heat treatment in nitrogen. The particle morphology of the precursor is preserved during the heat treatments. Excellent electrochemical properties in terms of capacity, reversibility, cycling stability and rate capability have been achieved. The thermal stability of charged electrodes is

G Arnold; J Garche; R Hemmer; S Ströbele; C Vogler; M Wohlfahrt-Mehrens

2003-01-01

177

A poly(3-decyl thiophene)-modified separator with self-actuating overcharge protection mechanism for LiFePO 4-based lithium ion battery  

Microsoft Academic Search

A voltage-sensitive separator is prepared simply by impregnating electroactive poly(3-decylthiophene) (P3DT) polymer into a commercial porous separator and tested for a self-actuating control of overcharge voltage of LiFePO4\\/C lithium-ion batteries. The experimental results demonstrate that this type of separator can be reversibly p-doped and dedoped to maintain the cell's voltage at a safe value of ?4V even at high rate

S. L. Li; L. Xia; H. Y. Zhang; X. P. Ai; H. X. Yang; Y. L. Cao

2011-01-01

178

LiFePO4 microcrystals as an efficient heterogeneous Fenton-like catalyst in degradation of rhodamine 6G  

PubMed Central

We present a novel heterogeneous Fenton-like catalyst of LiFePO4 (LFP). LFP has been widely used as an electrode material of a lithium ion battery, but we observed that commercial LFP (LFP-C) could act as a good Fenton-like catalyst to decompose rhodamine 6G. The catalytic activity of LFP-C microparticles was much higher than a popular catalyst, magnetite nanoparticles. Furthermore, we found that the catalytic activity of LFP-C could be further increased by increasing the specific surface area. The reaction rate constant of the hydrothermally synthesized LFP microcrystals (LFP-H) is at least 18 times higher than that of magnetite nanoparticles even though the particle size of LFP is far larger than magnetite nanoparticles. The LFP catalysts also exhibited a good recycling behavior and high stability under an oxidizing environment. The effects of the experimental parameters such as the concentration of the catalysts, pH, and the concentration of hydrogen peroxide on the catalytic activity of LFP were also analyzed.

2014-01-01

179

Cell degradation in commercial LiFePO4 cells with high-power and high-energy designs  

NASA Astrophysics Data System (ADS)

A quantitative analysis is presented to determine the degradation modes attributing to capacity fade in commercial LiFePO4 cells with high-power (HP) and high-energy (HE) designs. The capacity fade in the HP cell is predominantly due to the loss of lithium inventory. The fade in the HE cell is much more complicated as a function of rate. Using techniques including rest-cell-voltage measurements to track state-of-charge, dQ/dV analysis to trace peak area variations, and mechanistic model simulations (by the ‘Alawa toolbox), the capacity fades in the initial 120 cycles and subsequent aging are analyzed and degradation modes identified. Detailed ‘Alawa simulation with careful experimental validation explains the complexity of degradation in the HE cell. Peculiar rate-dependent initial capacity increases at rates higher than C/5 was likely attributed to electrochemical milling, resulting in active surface area increases and reduced polarization resistance (as the actual current density in the positive electrode was reduced). The mechanistic model and simulation capability illustrates the merits of this unique diagnostic approach with unprecedented holistic quantitative resolution for complicated cell degradation that seems hardly resolvable by other diagnostic methods.

Dubarry, Matthieu; Truchot, Cyril; Liaw, Bor Yann

180

Polaron formation and transport in olivine cathode materials  

NASA Astrophysics Data System (ADS)

One of the critical factors limiting Li ion battery performance is electronic conduction through the cathode material. In the olivine structure type materials, such as LiFePO4, the parent materials are insulators with a gap of approximately 4 (or more) eV. The withdrawal of an electron results not in a band-type hole state, but rather a localized polaronic state. Transport then occurs via hopping of the polaron through the crystal. The measured electronic conduction in olivine materials depends on the transition metal cation type. In this study, we use density functional theory to compare formation of polarons in olivine materials with different transition metal cations: Mn, Fe, Co, and Ni. We show that the underlying electronic structure of the fully lithiated material (or fully delithiated material) essentially determines whether or not polaron formation is possible in localized d-states or whether the holes that result from adding or removing an electron reside in oxygen-derived states. We also investigate the facility of polaronic hopping by calculating the barrier between adjacent polaron sites in each of the four materials.

Johannes, Michelle; Hoang, Khang

2011-03-01

181

Olivine Thermometry  

NSDL National Science Digital Library

This assignment is ostensibly about geothermometry, but is also part of a sequence of assignments where students learn about mineral components â what they represent (in regards to solid solution phenomena especially), and how they calculated. I begin with olivine because its components are simple, and reasonably good thermometers do not require long equations. I also use this assignment to teach about binary solid solutions and phase diagrams, though the interpretations of such are based within other assignments. This is part of a sequence of assignments where students learn about mineral components â what they represent (in regards to solid solution phenomena especially), and how they calculated. Though students will not use a binary solid solution diagram per se, I use this HW assignment to re-emphasize such concepts. This assignment also allows students to begin tests of equilibrium, so they must understand the concept and use of an equilibrium constant.

Putirka, Keith

182

Synthesis and performances of 2LiFePO4·Li3V2(PO4)3/C cathode materials via spray drying method with double carbon sources  

NASA Astrophysics Data System (ADS)

The 2LiFePO4·Li3V2(PO4)3/C samples are synthesized through spray drying method. Glucose and oxalic acid are used as collaborative carbon sources to improve the electrochemical performance of 2LiFePO4·Li3V2(PO4)3/C composites. XRD results reveal the LiFePO4·Li3V2(PO4)3/C samples are composed of orthorhombic LiFePO4 and monoclinic Li3V2(PO4)3 phases. SEM results reveal that the nano-spherical Fe4(VO4)4·5H2O are about 80 nm and the 2LiFePO4·Li3V2(PO4)3/C composites possess a micro-nano spherical morphology with carbon coating layer. The samples show the best electrochemical performance when the mass ration of glucose and oxalic is 6:4, it can deliver a capacity of 147.6 mAh g-1, 145.0 mAh g-1, 134.1 mAh g-1 and 123.0 mAh g-1 at the rates of 0.1C, 1C, 5C and 10C, respectively.

Zhang, Jia-feng; Shen, Chao; Zhang, Bao; Zheng, Jun-chao; Peng, Chun-li; Wang, Xiao-wei; Yuan, Xin-bo; Li, Hui; Chen, Guo-min

2014-12-01

183

Sucrose-assisted loading of LiFePO4 nanoparticles on graphene for high-performance lithium-ion battery cathodes.  

PubMed

A simple approach for loading LiFePO4 (LFP) nanoparticles on graphene (G) that could assemble amorphous LiFePO4 nanoparticles into a stable, crystalline, graphene-modified layered materials (G-S-LFP, S=sucrose) by using graphene as building block and sucrose as a linker has yet to be developed. On the basis of differential scanning calorimetric and transmission electron microscopy analysis of the samples from controlled experiment, a possible mechanism was proposed to explain the "linker" process of LFP and graphene with sucrose as the linker. The electrochemical properties of the samples as cathode material for lithium-ion batteries were studied by cyclic voltammogrametry and galvanostatic methods. Results showed that G-S-LFP displayed superior lithium-storage capability with current density changes randomly form 0.5 to 10 C. The significant improvement for rate and cycle performance could be attributed to the high conductivity of the graphene host, the high crystallinity, and the layered structure. PMID:23468054

Wu, Yongmin; Wen, Zhenhai; Feng, Hongbin; Li, Jinghong

2013-04-26

184

Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance.  

PubMed

In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol-gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4 nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm(-2) at 0.1 mA cm(-2) (lowest rate) and 1.1 mA h cm(-2) at 6 mA cm(-2) (highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium. PMID:24954747

Asfaw, Habtom D; Roberts, Matthew R; Tai, Cheuk-Wai; Younesi, Reza; Valvo, Mario; Nyholm, Leif; Edström, Kristina

2014-07-10

185

Direct Observation of Active Material Concentration Gradients and Crystallinity Breakdown in LiFePO4 Electrodes During Charge/Discharge Cycling of Lithium Batteries  

PubMed Central

The phase changes that occur during discharge of an electrode comprised of LiFePO4, carbon, and PTFE binder have been studied in lithium half cells by using X-ray diffraction measurements in reflection geometry. Differences in the state of charge between the front and the back of LiFePO4 electrodes have been visualized. By modifying the X-ray incident angle the depth of penetration of the X-ray beam into the electrode was altered, allowing for the examination of any concentration gradients that were present within the electrode. At high rates of discharge the electrode side facing the current collector underwent limited lithium insertion while the electrode as a whole underwent greater than 50% of discharge. This behavior is consistent with depletion at high rate of the lithium content of the electrolyte contained in the electrode pores. Increases in the diffraction peak widths indicated a breakdown of crystallinity within the active material during cycling even during the relatively short duration of these experiments, which can also be linked to cycling at high rate.

2014-01-01

186

Performance qualification and Raman investigation on cell behavior and aging of LiFePO4 cathodes in lithium-ion batteries  

NASA Astrophysics Data System (ADS)

This thesis explores the ability of Raman spectroscopy to understand the complex chemistry taking place in LiFePO4 cathodes of Li ion batteries. The performance of Li ion batteries was optimized through electrode fabrication and assembling procedures. Various amounts of Timcal Super P carbon were used to construct a conductive network of C-LiFePO4 particles and the performance of the cathodes was examined during battery cycling. Raman spectroscopy along with electrochemical characterization such as charge/ discharge curves, electrochemical impedance spectroscopy and Cyclic Voltammetry was employed for detailed investigation of battery performance and aging. It is found that both quantity and quality of the conductive carbon affect the rate performance and cyclic behavior of the cells. The cathodes with 2% additive carbon showed a faster capacity fading during cycling than that with 10% additive carbon due to a quicker degradation of the conductive network as indicated by sp2/sp3 and ID/IG ratios in Raman spectroscopy results. The rate performance of cathodes with 2%, 10% and 20 % carbon was also compared and a better rate performance was found for 2% carbon. It showed a proper electronic network which is mostly provided by carbon coating along with a large pore size of the cathode which facilitates the electrolyte penetration. Furthermore, in situ Raman spectroscopy was employed to probe electrolyte concentration variation at the cathode LiFePO4 particle surface in an optically transparent lithium ion cell. A Raman laser spot size of 2 microm was applied so that transport dynamics at individual particle surface could be investigated. The variation of Li+ concentration in the LiPF6/ethylene carbonate (EC) + dimethyl carbonate (DMC) electrolyte was determined, for the first time. This was done by monitoring the C--O stretching vibration signal intensity and the corresponding relationship to EC solvation. The electrolyte concentration at the LiFePO 4 particle surface was found to fluctuate during the battery charge/discharge cycle. Particularly, near the end of battery discharge, it reached to a minimum value which was far less than its initial balanced value (1 mol.dm -3).

Salehi, Amir

187

Olivines and olivine coronas in mesosiderites  

NASA Technical Reports Server (NTRS)

The paper presents a study of olivines and their surrounding coronas in mesosiderites texturally and compositionally using optical and microprobe methods. Olivine composition ranges from Fo(58-92) and shows no consistent pattern of distribution within and between mesosiderites; olivine occurs as large single crystals or as partially recrystallized mineral clasts, except for two lithic clasts. These are Emery and Vaca Muerta, and both are shock-modified olivine orthopyroxenites. Fine-grained coronas surround olivine, except for those in impact-melt group mesosiderites and those without tridymite in their matrices. Coronas consist largely of orthopyroxene, plagioclase, clinopyroxene, chromite, merillite, and ilmenite, and are similar to the matrix, but lack metal and tridymite. Texturally the innermost parts of the corona can be divided into three stages of development: (1) radiating acicular, (2) intermediate, and (3) granular.

Nehru, C. E.; Zucker, S. M.; Harlow, G. E.; Prinz, M.

1980-01-01

188

Olivines and olivine coronas in mesosiderites  

NASA Astrophysics Data System (ADS)

The paper presents a study of olivines and their surrounding coronas in mesosiderites texturally and compositionally using optical and microprobe methods. Olivine composition ranges from Fo(58-92) and shows no consistent pattern of distribution within and between mesosiderites; olivine occurs as large single crystals or as partially recrystallized mineral clasts, except for two lithic clasts. These are Emery and Vaca Muerta, and both are shock-modified olivine orthopyroxenites. Fine-grained coronas surround olivine, except for those in impact-melt group mesosiderites and those without tridymite in their matrices. Coronas consist largely of orthopyroxene, plagioclase, clinopyroxene, chromite, merillite, and ilmenite, and are similar to the matrix, but lack metal and tridymite. Texturally the innermost parts of the corona can be divided into three stages of development: (1) radiating acicular, (2) intermediate, and (3) granular.

Nehru, C. E.; Zucker, S.; Harlow, G. E.; Prinz, M.

1980-08-01

189

Enhanced electrochemical properties of LiFePO4 (LFP) cathode using the carboxymethyl cellulose lithium (CMC-Li) as novel binder in lithium-ion battery.  

PubMed

Novel water-based binder CMC-Li is synthesized using cotton as raw material. The mechanism of the CMC-Li as a binder is reported. Electrochemical properties of batteries cathodes based on commercially available lithium iron phosphate (LiFePO4, LFP) and CMC-Li as a water-soluble binder are investigated. CMC-Li is a novel lithium-ion binder. Compare with conventional poly(vinylidene fluoride) (PVDF) binder, and the battery with CMC-Li as the binder retained 97.8% of initial reversible capacity after 200 cycles at 176mAhg(-1), which is beyond the theoretical specific capacity of LFP. Constant current charge-discharge test results demonstrate that the LFP electrode using CMC-Li as the binder has the highest rate capability, follow closely by that using PVDF binder. The batteries have good electrochemical property, outstanding pollution-free and excellent stability. PMID:25037391

Qiu, Lei; Shao, Ziqiang; Wang, Daxiong; Wang, Wenjun; Wang, Feijun; Wang, Jianquan

2014-10-13

190

Synthesis of TiO2 hollow nanofibers by co-axial electrospinning and its superior lithium storage capability in full-cell assembly with olivine phosphate  

NASA Astrophysics Data System (ADS)

We report the formation and extraordinary Li-storage properties of TiO2 hollow nanofibers by co-axial electrospinning in both the half-cell and full-cell configurations. Li-insertion properties are first evaluated as anodes in the half-cell configuration (Li/TiO2 hollow nanofibers) and we found that reversible insertion of ~0.45 moles is feasible at a current density of 100 mA g-1. The half-cell displayed a good cyclability and retained 84% of its initial reversible capacity after 300 galvanostatic cycles. The full-cell is fabricated with a commercially available olivine phase LiFePO4 cathode under optimized mass loading. The LiFePO4/TiO2 hollow nanofiber cell delivered a reversible capacity of 103 mA h g-1 at a current density of 100 mA g-1 with an operating potential of ~1.4 V. Excellent cyclability is noted for the full-cell configuration, irrespective of the applied current densities, and it retained 88% of reversible capacity after 300 cycles in ambient conditions at a current density of 100 mA g-1.We report the formation and extraordinary Li-storage properties of TiO2 hollow nanofibers by co-axial electrospinning in both the half-cell and full-cell configurations. Li-insertion properties are first evaluated as anodes in the half-cell configuration (Li/TiO2 hollow nanofibers) and we found that reversible insertion of ~0.45 moles is feasible at a current density of 100 mA g-1. The half-cell displayed a good cyclability and retained 84% of its initial reversible capacity after 300 galvanostatic cycles. The full-cell is fabricated with a commercially available olivine phase LiFePO4 cathode under optimized mass loading. The LiFePO4/TiO2 hollow nanofiber cell delivered a reversible capacity of 103 mA h g-1 at a current density of 100 mA g-1 with an operating potential of ~1.4 V. Excellent cyclability is noted for the full-cell configuration, irrespective of the applied current densities, and it retained 88% of reversible capacity after 300 cycles in ambient conditions at a current density of 100 mA g-1. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01128c

Zhang, X.; Aravindan, V.; Kumar, P. Suresh; Liu, H.; Sundaramurthy, J.; Ramakrishna, S.; Madhavi, S.

2013-06-01

191

Preparation and electrochemical properties of high-capacity LiFePO4-Li3V2(PO4)3/C composite for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

LiFePO4-Li3V2(PO4)3/C (LFP-LVP/C) composite is prepared by a modified solid-state method, along with LFP/C composite as a reference. The structure and morphology of the as-prepared materials are analyzed by X-ray diffraction (XRD) and electron microscopy. LFP-LVP/C composite is well-crystallized and a matrix is formed by conductive carbon surrounding the LFP-LVP particles. LFP-LVP/C exhibits V-doped LFP in the bulk phase as determined by Rietveld analysis of XRD data, and mixed phase regions of V-doped LFP and LVP when analyzed at the particle-scale using high-resolution transmission electron microscopy. Electrochemical tests show that the initial discharge capacity of the LFP-LVP/C composite is 165.2 mAh g-1 at 0.1 C. Furthermore, the composite exhibits excellent performance with an initial discharge capacity of 135.4 mAh g-1 at a constant current density of 1 C, with no noticeable capacity fading after 100 cycles (141.6 mAh g-1), which is higher than that of LFP/C prepared by the same method for comparison. Thus, the introduction of LVP acts to improve electronic conductivity and Li+ diffusion of LFP/C.

Guo, Yong; Huang, Yudai; Jia, Dianzeng; Wang, Xingchao; Sharma, Neeraj; Guo, Zaiping; Tang, Xincun

192

First-principles investigation of the structural, magnetic, and electronic properties of olivine LiFeP O4  

NASA Astrophysics Data System (ADS)

We present a first-principles investigation of the structural, magnetic, and electronic properties of LiFePO4 olivine. The ground-state antiferromagnetic spin arrangement consistent with a superexchange mechanism through oxygen orbits is found to be preferred, showing an antiferromagnetic order between corner sharing octahedra along the [010] direction. This is in agreement with an oxygen-mediated superexchange mechanism for the iron-iron magnetic interaction. The theoretical Néel temperature estimated by a mean-field approximation is in the range between 33.1K and 53.5K , in acceptable agreement with the experimental susceptibility measurement, which gives TN=52K . The calculated magnetic moment of 3.72?B is close to the value of 4?B deduced from the ionic model according to the Hund’s rule.

Shi, Siqi; Ouyang, Chuying; Xiong, Zhihua; Liu, Lijun; Wang, Zhaoxiang; Li, Hong; Wang, Ding-Sheng; Chen, Liquan; Huang, Xuejie

2005-04-01

193

Olivine-rich asteroids, pallasitic olivine and olivine-metal mixtures: Comparisons of reflectance spectra  

NASA Technical Reports Server (NTRS)

The recent acquisition of high resolution 0.3 - 2.6 micron reflectance spectra for a number of olivine-rich asteroids permits the analysis of their surface compositions to be made on the basis of new and existing laboratory spectral data for pallasitic olivines and olivine-metal mixtures. Analysis of the spectral data for the latter has revealed a number of spectral parameters which can be used to constrain olivine and metal abundances, grain sizes, and olivine compositions. The following topics are discussed in greater detail: pallasite olivine spectra, olivine-metal mixture spectra, and olivine-rich asteroid spectra.

Cloutis, E. A.

1993-01-01

194

Synthesis of TiO2 hollow nanofibers by co-axial electrospinning and its superior lithium storage capability in full-cell assembly with olivine phosphate.  

PubMed

We report the formation and extraordinary Li-storage properties of TiO2 hollow nanofibers by co-axial electrospinning in both the half-cell and full-cell configurations. Li-insertion properties are first evaluated as anodes in the half-cell configuration (Li/TiO2 hollow nanofibers) and we found that reversible insertion of ~0.45 moles is feasible at a current density of 100 mA g(-1). The half-cell displayed a good cyclability and retained 84% of its initial reversible capacity after 300 galvanostatic cycles. The full-cell is fabricated with a commercially available olivine phase LiFePO4 cathode under optimized mass loading. The LiFePO4/TiO2 hollow nanofiber cell delivered a reversible capacity of 103 mA h g(-1) at a current density of 100 mA g(-1) with an operating potential of ~1.4 V. Excellent cyclability is noted for the full-cell configuration, irrespective of the applied current densities, and it retained 88% of reversible capacity after 300 cycles in ambient conditions at a current density of 100 mA g(-1). PMID:23712615

Zhang, X; Aravindan, V; Kumar, P Suresh; Liu, H; Sundaramurthy, J; Ramakrishna, S; Madhavi, S

2013-07-01

195

REE Diffusion in Olivine  

NASA Astrophysics Data System (ADS)

Diffusion of rare earth elements has been characterized in synthetic forsterite and natural olivine (Fo90) under dry conditions. The source of diffusant was a mixture of REE aluminate garnet powder and synthetic forsterite powder in 3:1 proportions. Experiments were prepared by enclosing source material and polished forsterite in platinum capsules, which were crimped shut. For experiments on natural olivine, samples were placed with the source in AgPd capsules, which were sealed under vacuum in silica glass ampoules with a solid buffer to buffer at NNO. Prepared capsules were then annealed in 1 atm furnaces for times ranging from an hour to several weeks, at temperatures from 850 to 1300°C. REE distributions in the olivine were profiled by Rutherford Backscattering Spectrometry (RBS). The following Arrhenius relation is obtained for Dy diffusion in forsterite: D = 2.3x10-10 exp(-273 kJ mol-1/RT) m2sec-1. Diffusivities of Yb and La in forsterite appear similar, and preliminary results for Dy diffusion in natural olivine also suggest similar diffusivities. REE diffusivities in forsterite are about an order of magnitude faster than those of REE+3 in enstatite (Cherniak and Liang, 2007). However, if the Arrhenius relation above is extrapolated up to 1450C, it yields diffusivities about three orders of magnitude smaller than those determined for REE diffusion in olivine by Spandler et al. (2007). Work is currently underway in further characterizing diffusion in Fe-bearing olivine. If an Arrhenius relation similar to that for forsterite is found to apply, timescales for preservation of REE signatures in olivine-hosted melt inclusions may be relatively long. Cherniak and Liang (2007) GCA 71, 1324-1340; Spandler et al. (2007) Nature 447, 303-306.

Cherniak, D. J.

2007-12-01

196

Artificial meteor ablation studies: Olivine  

NASA Technical Reports Server (NTRS)

Artificial meteor ablation was performed on a Mg-rich olivine sample using an arc-heated plasma of ionized air. Experimental conditions simulated a meteor traveling about 12 km/sec at an altitude of 70 km. The mineral content of the original olivine sample was 98% olivine (including traces of olivine alteration products) and 2% chromite. Forsterite content of the original olivine was Fo-89. After ablation, the forsterite content had increased to Fo-94 in the recrystallized olivine. In addition, lamella-like intergrowths of magnetite were prevalent constituents. Wherever magnetite occurred, there was an increase in Mg and a corresponding decrease in Fe for the recrystallized olivine. The Allende fusion crust consisted of a recrystallized olivine, which was more Mg-rich and Fe-deficient than the original meteorite's olivine, and abundant magnetite grains. Although troilite and pentlandite were the common opaque mineral constituents in this meteorite, magnetite was the principal opaque mineral found in the fusion crust.

Blanchard, M. B.; Cunningham, G. G.

1973-01-01

197

Sintering of olivine and olivine-basalt aggregates  

Microsoft Academic Search

The sintering behavior of olivine and olivine-basalt aggregates has been examined at temperatures near 1,300° C. Experimental factors contributing to rapid sintering kinetics and high-density, fine-grained specimens include: (i) the uniform dispersion of basalt throughout the specimen, (ii) a very fine, uniform particle size for the olivine powder, (iii) oxygen fugacities near the high PO2 end of the olivine stability

R. F. Cooper; D. L. Kohlstedt

1984-01-01

198

Olivine Crystal Structure  

NSDL National Science Digital Library

This exercise is based on recent crystallographic research on the olivine crystal structure published by Redfern et al. (2000). The authors of this study synthesized Fa50 olivine olivine (MgFeSiO4) in an experimental apparatus at temperatures ranging from 100 to 1250 °C, quenched the experiments, and used in situ neutron powder diffraction techniques to investigate changes in the synthesized olivines as a function of temperature. While this study reports cutting-edge materials research carried out with the latest crystallographic techniques, the results are educationally instructive and illustrate important concepts normally covered in an undergraduate mineralogy course. In this exercise, students are guided into the American Mineralogist Crystal Structure Database to retrieve and download published crystal structure data for viewing in either the CrystalMaker or XtalDraw visualization software packages. The students are instructed on how to manipulate the structures and are asked to plot some of the crystallographic data from this study on graphs using a spreadsheet program such as Excel.

Ratajeski, Kent

199

Synthesis and Performance of LiFe1-xMnxPO4 in Lithium-ion Battery  

NASA Astrophysics Data System (ADS)

Olivine-type lithium transition metal phosphates (i.e. LiFePO4) have been intensively investigated as promising electrode materials for rechargeable lithium-ion batteries. There have been attempts to improve energy density and voltage quality of phosphate based electrode. In this study, we have partially substituted Fe^II/Fe^III redox center with Mn^II/Mn^III in LiFePO4 that provides over 600 mV higher voltage. We prepared various compositions of LiFe1-xMnxPO4 (x=0, 0.2, 0.4, 0.6, 0.8 and 1) between the two end members (LiFePO4 - LiMnPO4). Due to intrinsic low electronic conductivity of lithium transition metal phosphates, we coat these materials with a uniform conductive carbon through a unique sol-gel process developed in our laboratory. In addition, we made a composite of the carbon coated phosphate with carbon nano-tubes to develop a highly conductive matrix electrode. We report the materials structure, morphology, electrical conductivity and electrochemical performances of LiFe1-xMnxPO4 using XRD, Raman spectroscopy, SEM, TEM, XPS, electrical conductivity and galvanostatic charge/discharge measurements.

Bazzi, Khadije; Nazri, Maryam; Vaishnava, Prem; Naik, Vaman; Nazri, Gholam-Abbas; Naik, Ratna

2013-03-01

200

Synthesis and properties of Co-doped LiFePO 4 as cathode material via a hydrothermal route for lithium-ion batteries  

Microsoft Academic Search

A series of olivine LiFe1?xCoxPO4 composites were synthesised by a hydrothermal route under reductive atmosphere. The structure of the prepared samples was characterised by X-ray diffraction. Morphology, particle size, and elemental concentration were observed by scanning electron microscopy, high-resolution transmission electron microscopy, and corresponding EDS mapping, respectively. Raman spectroscopy was employed to study the surface information of the carbon-coated LiFe1?xCoxPO4.

Rui-rui Zhao; I-Ming Hung; Yi-Ting Li; Hong-yu Chen; Chun-Peng Lin

201

Electrical Conductivity of Olivine  

Microsoft Academic Search

The electrical conductivity a of single crystals of olivine of 0, 7.7, 8.2, 9.4, and 26.4 mole % fayalite has been measured up to 1200øC and 7.5 kb. Samples from different localities with approximately the same fayalite content and impurity levels have electrical conductivities that differ by 2-3 orders of magnitude. It is proposed that the oxidation state of the

Al Duba

1972-01-01

202

Minor elements in Marjalahti olivine  

NASA Astrophysics Data System (ADS)

Precise microprobe determinations of minor elements in olivine from Marjalahti show averages of 0.0267 percent CaO; 0.0211 percent Cr2O3; less than 0.0045 percent TiO2; 0.288 percent MnO; and 30 ppm Ni. The calcium is as high as in some terrestrial plutonic olivines (e.g. Stillwater) but lower than in terrestrial nodule (high-temperature mantle?) olivines, consistent with very slow cooling to low temperatures. The chromium is discrepant with some earlier determinations, and possibly chromium is zoned in most pallasitic olivines. The Ti, Mn, and Ni data are consistent with previous determinations.

Ryder, G.

1984-06-01

203

Helium Diffusion in Olivine  

NASA Astrophysics Data System (ADS)

Diffusion of helium has been characterized in natural Fe-bearing olivine (~Fo90) and synthetic forsterite. Polished, oriented slabs of olivine were implanted with 3He, at 100 keV at a dose of 5x1015/cm2 or at 3.0 MeV at a dose of 1x1016/cm2. A set of experiments on the implanted olivine were run in 1-atm furnaces. In addition to the one-atm experiments, experiments on implanted samples were also run at higher pressures (2.6 and 2.7 GPa) to assess the potential effects of pressure on He diffusion and the applicability of the measured diffusivities in describing He transport in the mantle. The high-pressure experiments were conducted in a piston-cylinder apparatus using an "ultra-soft" pressure cell, with the diffusion sample directly surrounded by AgCl. 3He distributions following experiments were measured with Nuclear Reaction Analysis using the reaction 3He(d,p)4He. This direct profiling method permits us to evaluate anisotropy of diffusion, which cannot be easily assessed using bulk-release methods. For diffusion in forsterite parallel to c we obtain the following Arrhenius relation over the temperatures 250-950°C: D = 3.91x10-6exp(-159 ± 4 kJ mol-1/RT) m2/sec. The data define a single Arrhenius line spanning more than 7 orders of magnitude in D and 700°C in temperature. Diffusion parallel to a appears slightly slower, yielding an activation energy for diffusion of 135 kJ/mol and a pre-exponential factor of 3.73x10-8 m2/sec. Diffusion parallel to b is slower than diffusion parallel to a (by about two-thirds of a log unit); for this orientation an activation energy of 138 kJ/mol and a pre-exponential factor of 1.34x10-8 m2/sec are obtained. This anisotropy is broadly consistent with observations for diffusion of Ni and Fe-Mg in olivine. Diffusion in Fe-bearing olivine (transport parallel to b) agrees within uncertainty with findings for He diffusion in forsterite. The higher-pressure experiments yield diffusivities in agreement with those from the 1-atm experiments, indicating that the results reported here can be reasonably applied to modeling He transport in the upper mantle. The insensitivity of He diffusion to pressure over the investigated range of conditions suggests that compression of the mineral lattice is not sufficient to significantly influence migration of the relatively small helium atoms, which likely diffuse via crystal interstices. The He diffusivities in this work are generally consistent with results from the study of Futagami et al. (1993), who measured He diffusion in natural olivine by outgassing 4He implanted samples, and with the diffusivities measured by bulk-release of 4He and 3He by Shuster et al. (2003), but are about 2 orders of magnitude slower than the recent findings of Tolstikhin et al. (2010) and Blard et al. (2008) . An up-temperature extrapolation of our data also show reasonable agreement with the higher-temperature measurements of Hart (1984). Blard et al. (2008) GCA 72, 3788-3803; Futagami et al. (1993) GCA 57, 3177-3194; Hart (1984) EPSL 70, 297-302; Shuster et al.( 2003) EPSL 217, 19-32; Tolstikhin et al. (2010) GCA 74, 1436-1447

Cherniak, D. J.; Watson, E. B.

2011-12-01

204

Electrical conduction in olivine  

SciTech Connect

This paper reports detailed measurements of electrical conductivitysigma and thermoelectric effect /ital S/ in the mineral olivine and in syntheticforsterite as functions of temperature in the range from 1000/degree/ to1500 /degree/C and oxygen partial pressure in the range from 10/sup /minus/10/ to10/sup 4/ Pa. The two most striking observations are strong conductivityanisotropy in forsterite and a sign change in /ital S/ in olivine at 1390 /degree/C.These results are interpreted to show that both materials have mixed ionic andextrinsic electronic conduction under these conditions. On the basis ofthese interpretations, we infer that forsterite conductivity is dominatedby electronic conduction in the /ital a/ and /ital b/ directions and probably bymovement involving magnesium vacancies in the /ital c/ direction, wherefar higher /ital P//sub O/sub 2//-independent conductivity is observed. Olivineappears to show mixed conduction under all the circumstances observed; at low temperature, electron holes dominate but are superseded bymagnesium vacancies at high temperatures./copyright/ American Geophysical Union 1989

Schock, R. N.; Duba, A. G.; Shankland, T. J.

1989-05-10

205

Formation conditions of pyroxene-olivine and magnesian olivine chondrules  

NASA Technical Reports Server (NTRS)

Dynamic crystallization experiments performed on a Type I and an intermediate Type II/III composition demonstrate chondrule texture is controlled by the abundance of heterogeneous nuclei. This factor is controlled by the maximum initial temperature relative to the olivine disappearance temperature for the given heating time. Glassy and excentroradial textures form from superheated melts with no nuclei, and barred textures form with initial temperatures near the olivine disappearance temperature. Porphyritic and granular textures form with initial temperatures below the liquidus with abundant nuclei. Comparison of zoning characteristics of experimental olivines with those in natural porphyritic olivine chondrules indicates cooling rates of 100 to 1000 C/h, whereas olivine morphology indicates barred olivines cooled at rates of 250 to 1000 C/h. Texture/composition relationships suggest chondrules experienced initial temperatures below 1750 C. These observations are consistent with the idea that chondrules formed by transient heating in dust-rich regions (i.e., in the midplane) of the solar nebula.

Radomsky, Patrick M.; Hewins, Roger H.

1990-01-01

206

Formation conditions of pyroxene-olivine and magnesian olivine chondrules  

SciTech Connect

Dynamic crystallization experiments performed on a Type I and an intermediate Type II/III composition demonstrate chondrule texture is controlled by the abundance of heterogeneous nuclei. This factor is controlled by the maximum initial temperature relative to the olivine disappearance temperature for the given heating time. Glassy and excentroradial textures form from superheated melts with no nuclei, and barred textures form with initial temperatures near the olivine disappearance temperature. Porphyritic and granular textures form with initial temperatures below the liquidus with abundant nuclei. Comparison of zoning characteristics of experimental olivines with those in natural porphyritic olivine chondrules indicates cooling rates of 100 to 1000{degree}C/h, whereas olivine morphology indicates barred olivines cooled at rates of 250 to 1,000{degree}C/h. Texture/composition relationships suggest chondrules experienced initial temperatures below 1,750{degree}C. These observations are consistent with the idea that chondrules formed by transient heating in dust-rich regions (i.e., in the midplane) of the solar nebula.

Radomsky, P.M.; Hewins, R.H. (Rutgers Univ., New Brunswick, NJ (USA))

1990-12-01

207

Olivine dissolution in basaltic melt  

NASA Astrophysics Data System (ADS)

The main purpose of this work is to understand and quantify diffusive and convective olivine dissolution in basaltic melt. Crystal dissolution and growth in a magma chamber is often accompanied by the descent or ascent of the crystal in the chamber due to gravity. The motion induces convection that enhances mass transport. Such convective dissolution and growth rates have not been quantified before. MgO diffusivity in the melt ( DMgO), MgO concentration of the interface melt ( C0) and the effective thickness of the compositional boundary layer (?) are necessary parameters to model the convective dissolution. Experiments of non-convective olivine dissolution in a basaltic melt were conducted at 1271-1480 °C and 0.47-1.42 GPa in a piston-cylinder apparatus. At specific temperature and pressure conditions, multiple experiments of different durations show that the interface melt reaches near-saturation within 2 min. Therefore, diffusion, not interface reaction, is the rate-controlling step for non-convective olivine dissolution in basaltic melt. The compositional profile length and olivine dissolution distance are proportional to the square root of experimental duration, consistent with diffusive dissolution. DMgO and C0 are obtained from the experimental results. DMgO displays Arrhenian dependence on temperature, but the pressure dependence is small and not resolved. C0 increases with increasing temperature and decreases with increasing pressure. Comparison with literature data shows that DMgO depends strongly on the initial melt composition, while C0 does not. ? is estimated from fluid dynamics. DMgO/?, which characterizes the kinetic and dynamic aspects of convective crystal dissolution, is parameterized as a function of temperature, pressure, and olivine composition. Convective olivine dissolution rate in basaltic melt can be conveniently calculated from the model results. Application to convective crystal growth and xenolith digestion is discussed.

Chen, Yang; Zhang, Youxue

2008-10-01

208

Structural and magnetic phase transition of mixed olivines LixFe1-yNiyPO4 by lithium deintercalation  

NASA Astrophysics Data System (ADS)

The structural and magnetic phase transitions of LixFe1-yNiyPO4 were investigated by x-ray diffraction (XRD), superconducting quantum interference device magnetometry, and Mössbauer spectroscopy. Rietveld refinement of XRD patterns of LiFe1-yNiyPO4 (0.0 <= y <= 0.6) revealed that the lattice parameters a0 = 10.328, b0 = 6.007, and c0 = 4.692 A? for LiFePO4 changed linearly to a0 = 10.154, b0 = 5.923, and c0 = 4.687 A? for LiFe0.4Ni0.6PO4 with the substitution of Ni ions. Also, the fully lithium-deintercalated Fe1-yNiyPO4 (0.0 <= y <= 0.6) series had enhanced lattice distortions along the c axis compared to LiFe1-yNiyPO4 because the Jahn-Teller distortion changed as the unit cell volume decreased due to lithium ion deintercalation. LiFe1-yNiyPO4 has an antiferromagnetic order; the magnetic Nèel temperature (TN) decreased from 51 K for LiFePO4 to 36 K for LiFe0.4Ni0.6PO4. Fully deintercalated Fe1-yNiyPO4 has strong antiferromagnetic order; TN decreased from 114 K for FePO4 to 62 K for Fe0.4Ni0.6PO4 due to the charge transition of Fe2+/Fe3+ and Ni2+/Ni3+, mediated by lithium ion vacancies in an olivine structure. The Mössbauer spectra below the TN of LixFe1-yNiyPO4 (x = 0, 1, 0.0 <= y <= 0.6) were fitted with eight asymmetrical Lorentzian functions. The electric quadrupole splitting value (?EQ) of LiFe1-yNiyPO4 is larger than that of Fe1-yNiyPO4 due to more asymmetric charge distributions around Fe2+ (3d6) than Fe3+ (3d5) in FeO6 sites.

Lee, In Kyu; Kim, Chin Mo; Kim, Sam Jin; Kim, Chul Sung

2012-04-01

209

Formation conditions of pyroxene-olivine and magnesian olivine chondrules  

Microsoft Academic Search

Dynamic crystallization experiments performed on a Type I and an intermediate Type II\\/III composition demonstrate chondrule texture is controlled by the abundance of heterogeneous nuclei. This factor is controlled by the maximum initial temperature relative to the olivine disappearance temperature for the given heating time. Glassy and excentroradial textures form from superheated melts with no nuclei, and barred textures form

P. M. Radomsky; R. H. Hewins

1990-01-01

210

Amoeboid olivine aggregates in the Allende meteorite  

Microsoft Academic Search

Greyish-brown irregularly-shaped aggregates composed predominantly of olivine make up nearly 2% of the Allende meteorite by volume. Many of the aggregates are constructed of subspherical lumps of micron-sized crystals of olivine, pyroxene, nepheline and sodalite surrounded by coarser-grained olivine. Rarely, anorthite, spinel and perovskite are also present. The olivine ranges in composition from Fo64 to Fo99. Pyroxenes range from aluminous

L. Grossman; I. M. Steele

1976-01-01

211

Electrochemical performance of V-doped spinel Li4Ti5O12/C composite anode in Li-half and Li4Ti5O12/LiFePO4-full cell  

NASA Astrophysics Data System (ADS)

This work reports the preparation of a V-doped Li4Ti5O12/C (donated as V-doped LTO/C) composite material, applying a solid-state method. Both metal doping and carbon coating are applied on the Li4Ti5O12 material, enhancing its rate capability and cycle stability. Furan polymer is used as a carbon source, and vanadium (V) is selected as a dopant. The properties of the materials are examined by X-ray diffraction (XRD), micro-Raman, scanning electron microscopy (SEM), high-resolution transmission microscopy (HR-TEM), the AC impedance method, and the galvanostatic charge/discharge method. For comparison, Li4Ti5O12/C composite materials with and without V doping are also examined. The Li4Ti4.90V0.10O12/C composite material achieves discharge capacities of 165.59 and 76.76 mAh g-1 at a 0.2/1C and 0.2/20C rate, respectively. A Li4Ti5O12/LiFePO4 full cell (LTO capacity-limited) is constructed and investigated. The full cell exhibits discharge capacities of 181, 178, 167, 142, 110, and 78 mAh g-1 at 0.2, 0.5, 1, 3, 5, and 10C, respectively. We determine that the Li4Ti4.95V0.05O12/C composite anode is an outstanding candidate for application in high-power Li-ion batteries.

Yang, Chun-Chen; Hu, Huai-Chou; Lin, S. J.; Chien, Wen-Chen

212

Supernova olivine from cometary dust  

NASA Technical Reports Server (NTRS)

An interplanetary dust particle contains a submicrometer crystalline silicate aggregate of probable supernova origin. The grain has a pronounced enrichment in 18O/16O (13 times the solar value) and depletions in 17O/16O (one-third solar) and 29Si/28Si (<0.8 times solar), indicative of formation from a type II supernova. The aggregate contains olivine (forsterite 83) grains <100 nanometers in size, with microstructures that are consistent with minimal thermal alteration. This unusually iron-rich olivine grain could have formed by equilibrium condensation from cooling supernova ejecta if several different nucleosynthetic zones mixed in the proper proportions. The supernova grain is also partially encased in nitrogen-15-rich organic matter that likely formed in a presolar cold molecular cloud.

Messenger, Scott; Keller, Lindsay P.; Lauretta, Dante S.

2005-01-01

213

Supernova olivine from cometary dust.  

PubMed

An interplanetary dust particle contains a submicrometer crystalline silicate aggregate of probable supernova origin. The grain has a pronounced enrichment in 18O/16O (13 times the solar value) and depletions in 17O/16O (one-third solar) and 29Si/28Si (<0.8 times solar), indicative of formation from a type II supernova. The aggregate contains olivine (forsterite 83) grains <100 nanometers in size, with microstructures that are consistent with minimal thermal alteration. This unusually iron-rich olivine grain could have formed by equilibrium condensation from cooling supernova ejecta if several different nucleosynthetic zones mixed in the proper proportions. The supernova grain is also partially encased in nitrogen-15-rich organic matter that likely formed in a presolar cold molecular cloud. PMID:15994379

Messenger, Scott; Keller, Lindsay P; Lauretta, Dante S

2005-07-29

214

Olivine-dominated asteroids: Mineralogy and origin  

NASA Astrophysics Data System (ADS)

Olivine-dominated asteroids are a rare type of objects formed either in nebular processes or through magmatic differentiation. The analysis of meteorite samples suggest that at least 100 parent bodies in the main belt experienced partial or complete melting and differentiation before being disrupted. However, only a few olivine-dominated asteroids, representative of the mantle of disrupted differentiated bodies, are known to exist. Due to the paucity of these objects in the main belt their origin and evolution have been a matter of great debate over the years. In this work we present a detailed mineralogical analysis of twelve olivine-dominated asteroids. We have obtained near-infrared (NIR) spectra (0.7-2.4 ?m) of asteroids (246) Asporina, (289) Nenetta, (446) Aeternitas, (863) Benkoela, (4125) Lew Allen and (4490) Bamberry. Observations were conducted with the Infrared Telescope Facility (IRTF) on Mauna Kea, Hawai'i. This sample was complemented with spectra of six other olivine-dominated asteroids including (354) Eleonora, (984) Gretia, (1951) Lick, (2501) Lohja, (3819) Robinson and (5261) Eureka obtained by previous workers. Within our sample we distinguish two classes, one that we call monomineralic-olivine asteroids, which are those whose spectra only exhibit the 1 ?m feature, and another referred to as olivine-rich asteroids, whose spectra exhibit the 1 ?m feature and a weak (Band II depth ˜4%) 2 ?m feature. For the monomineralic-olivine asteroids the olivine chemistry was found to range from ˜Fo49 to Fo70, consistent with the values measured for brachinites and R chondrites. In the case of the olivine-rich asteroids we determined their olivine and low-Ca pyroxene abundance using a new set of spectral calibrations derived from the analysis of R chondrites spectra. We found that the olivine abundance for these asteroids varies from 0.68 to 0.93, while the fraction of low-Ca pyroxene to total pyroxene ranges from 0.6 to 0.9. A search for dynamical connections between the olivine-dominated asteroids and asteroid families found no genetic link (of the type core-mantel-crust) between these objects.

Sanchez, Juan A.; Reddy, Vishnu; Kelley, Michael S.; Cloutis, Edward A.; Bottke, William F.; Nesvorný, David; Lucas, Michael P.; Hardersen, Paul S.; Gaffey, Michael J.; Abell, Paul A.; Corre, Lucille Le

2014-01-01

215

Origin of olivine in kimberlite: Phenocryst or impostor?  

NASA Astrophysics Data System (ADS)

Kimberlite hosts two populations of olivine that are distinguished on the basis of grain size and morphology; the populations are commonly described genetically as xenocrysts and phenocrysts. Olivine xenocrysts or macrocrysts are thought to derive from disaggregation of mantle xenoliths whereas the smaller, euhedral olivine crystals are presumed entirely cognate to the kimberlite melt. Recent studies of zoning patterns of euhedral olivine in kimberlite have, however, cast doubt on the actual origins of the smaller olivine crystals. Here, we elucidate the nature and origins of the textural and chemical zonation that characterize both populations of olivine: macrocrysts (olivine-I) and euhedral crystals (olivine-II). Specifically, we show that both olivine-I and olivine-II feature chemically distinct overgrowths resulting from heterogeneous crystallization onto pre-existing olivine xenocrysts. Our analysis limits the total volume of olivine crystallized during transport to ? 5% in contrast to previous estimates of ~ 25%. The reduced extent of olivine crystallization allows for closer reconciliation of crystallized olivine compositions and estimates of Mg#s for primitive kimberlite melts. It also places constraints on processes involving orthopyroxene assimilation by kimberlite melt. If olivine crystallization and orthopyroxene assimilation are coupled, then orthopyroxene assimilation is limited to ~ 7%. Larger masses of orthopyroxene assimilation (i.e. 25%) are possible only if kimberlite magmas originate at super-liquidus (> 100 ºC) conditions and sub-equal amounts of olivine crystallization occurs.

Brett, R. C.; Russell, J. K.; Moss, S.

2009-11-01

216

Cations in olivine, Part 2: Diffusion in olivine xenocrysts, with applications to petrology and mineral physics  

Microsoft Academic Search

Diffusivities for calcium, iron, magnesium, manganese and aluminum have been measured for St. John's olivine undergoing cation exchange with synthetic basaltic melts. The variety of temperature, pressure and fO2 conditions under which the diffusivities were measured complement the equilibrium-partitioning study of calcium in olivine-bearing basalts by Jurewicz and Watson, 1988. Olivine was found to be anisotropic with respect to the

Amy J. G. Jurewicz; E. Bruce Watson

1988-01-01

217

Exsolved kirschsteinite in angrite LEW86010 olivine  

NASA Technical Reports Server (NTRS)

Mineralogy of kirschsteinite exsolution in olivine from Antarctic meteorite LEW86010 has been studied by single crustal X-ray diffraction technique. The LEW86010 olivine crystals have exsolution lamellae of kirschteinite about 15 microns wide. Determination of crystallographic orientation of exsolved kirschsteinite in an olivine grain has been made. Weak reflections of exsolved kirschsteinite share common crystallographic orientation with the host olivine. The cell dimensions of the exsolved phase (a - 4.87 plus or minus 0.05A, b - 11.14 plus or minus 0.10A, c - 6.36 plus or minus 0.05A) and intensities were in well accord with those of kirschsteinite previously reported. Oriented section perpendicular to the a axis shows exsolution lamellae in two directions parallel to (031) and (031). The lamellae are up to 10 microns in width and spacings between them are usually 50-100 microns.

Mikouchi, Takashi; Takeda, Hiroshi; Mori, Hiroshi; Miyamoto, Masamichi; Mckay, Gordon

1993-01-01

218

Atom Probe Tomography of Olivine  

NASA Astrophysics Data System (ADS)

Here we present atom probe tomographic (APT) analyses of natural olivine. APT provides three-dimensional trace element and isotopic analysis with sub-nanometer spatial resolution. It has been used for many years in engineering and materials science, but has not been applied to geological materials because traditional APT can only be used on conducting (usually metal) samples. The recent development of laser assisted APT has changed this situation, and now semi-conductors and insulators can be analyzed (Marquis et al., 2009, Kelly et al 2007). Potentially, this opens APT to extensive use in geoscience as many Fe-bearing silicates are semi-conductors. In this study, we explore the capability of the new class of APT instrumentation to analyze geological materials. APT involves the controlled evaporation of small, cylindrical specimens (100's nm in diameter) within an electric field. Specimens are typically prepared using in-situ focused-ion-beam (FIB) liftout and shaping techniques. Evaporated atoms are accelerated to a detector plate that records the position of the atom with sub-nm precision. Evaporated atoms are measured using time-of-flight mass spectrometry, allowing both elemental and isotopic determination. Since the method progressively ablates into the needle, the final analytical result is a nm-scale 3-dimensional image in which the position and identity of each detected atom is known. Typical mass resolution is between 200 and 1200 (full-width at half maximum) and typical concentration detection limits are 10 ppm. The number of potential applications of APT to igneous, metamorphic and sedimentary materials is large, ranging from studies of mineral and melt inclusions, to fine scale layering in minerals, to reaction surfaces and diffusion profiles. Much recent progress in the geochemical and petrologic fields has been driven by the increasing spatial resolution of the ion probe and laser ablation ICPMS. The ability of APT to provide atom-scale mass spectrometry should continue this trend. The main limitations to atom probe analysis of geological materials are the ability to control heat flow during laser pulsing and the associated ability to control clustering during field evaporation. Both of these factors can be controlled through specimen preparation and varying the atom probe experimental factors. Olivine specimens were properly analyzed using laser pulsed APT through the use of shallow (nominally 1mm) FIB liftouts and wide shank angle specimen apices. APT settings were found to give the best mass resolution using low specimen temperatures, 0.2 nJ laser energy, and 50 kHz pulse repetition rate. Increasing any of these values increases the amount of thermal tails due to excessive heat buildup, reducing the mass spectrum resolution, and ultimately affecting the spatial resolution of the reconstruction. Marquis EA, Miller MK, Blavette D, Ringer SP, Sudbrack CK and Smith DW (2009). MRS Bulletin 34: 725-730. Thomas F. Kelly, David J. Larson, Keith Thompson, Roger L. Alvis, Joseph H. Bunton, Jesse D. Olson, Brian P. Gorman, Ann. Rev. Mat. Res. 37: 681-727.

Parman, S. W.; Gorman, B.; Jackson, C.; Cooper, R. F.; Jaeger, D.

2010-12-01

219

Incompatible Trace Element Abundances in Hawaiian Olivines  

NASA Astrophysics Data System (ADS)

Our understanding of trace elements partitioning between olivine and silicate melt is clouded by large variations in values of partition coefficients presented in the literature. In general, partition coefficients from phenocryst-matrix results are higher than those from experimental equilibration and in-situ measurements (such as LA-ICP-MS and Ion-probe) (Blard and Farley, 2008; Lee et al., 2007). This discrepancy is possibly caused by the presence of melt or micromineral inclusions in the analyzed phenocrysts, or contamination of grain boundaries by enriched glasses or accessory phases or uranium pick up from alteration of olivines. To further investigate why analysis of natural phenocrysts usually results in relative high apparent D’s for incompatible trace elements, six aliquots of olivine grains from a single sediment sample of Waimea river watershed, on the western side of the island of Kauai, Hawaii, were analyzed by solution ICP-MS at Harvard University for trace element concentrations. Two aliquots of olivines were leached in 1% oxalic acid for 45-60 min at 90 OC before dissolution. Leached and unleached olivines mostly show positive linear correlations in plots of incompatible trace elements versus La, which possibly indicates mixing lines between olivine and one end-member with higher incompatible element concentration (possibly melt inclusion). Assuming La concentration in olivine is zero, we estimate concentration of other incompatible elements in olivines using intercepts of these mixing lines. We obtain that U and Th concentration in the olivines to be about 1 ppb and 0.1 ppb respectively, corresponding to apparent DUol/melt and DThol/melt of 0.003 and 0.0001 if host lave has U of 0.3 ppm and Th of 1ppm (Gayer et al.,2008). Recently, helium isotopic measurements were made in these olivines (Gayer et al., 2008) and the results yield a basin-wide average erosion rate of 0.056 mma-1 for Waimea river watershed. Gayer et al. (2008) argued that radiogenic 4He in these ~4.5 Ma old olivines is negligible using DUol/melt=2×10-5 and DThol/melt=5×10-5 (Beattie 1993; Kennedy et al., 1993) and 0.3 ppm U and 1 ppm Th for host lavas. This assumption has been challenged by Blard and Farley (2008), who argued that radiogenic 4He in these olivines are significant and could affect the calculated erosion rate by a factor of 10-100. They used apparent DUol/melt and DThol/melt ranging between 0.03 and 0.1, which were obtained from analyses of whole natural phenocrysts and host lava (Blard and Farley, 2008). In contrast, using our measured U and Th contents in the Kauai olivines suggest revisions to erosion rates on order of only 15%. Therefore, Blard and Farley (2008)’s apparent D values may not be representative of Kauai olivines and their assertion that Gayer et al. (2008)’s erosion rates from Hawaii require revision by more than a factore of 10 is incorrect.

Yu, G.; Huang, S.; Mukhopadhyay, S.; Jacobsen, S. B.

2009-12-01

220

Electronic Properties of LiFePO4 and Li doped LiFePO4  

SciTech Connect

LiFePO{sub 4} has several potential advantages in comparison to the transition metal oxide cathode materials used in commercial lithium-ion batteries. However, its low intrinsic electronic conductivity ({approx} 10{sup -9} S/cm) is problematic. We report here a study by soft x-ray absorption/emission spectroscopy of the electronic properties of undoped LiFePO{sub 4} and Li-doped LiFePO{sub 4} in which Li{sup +} ions are substituted for Fe{sup 2+} ions in an attempt to increase the intrinsic electronic conductivity. The conductivities of the Li{sub 1+x}Fe{sub 1-x}PO{sub 4} samples were, however, essentially unchanged from that of the undoped LiFePO{sub 4}. Nonetheless, evidence for changing the electronic properties of LiFePO{sub 4} by doping with excess Li+ was observed by the XAS/XES spectroscopy. New pre-edge features the O-1s XAS spectrum of Li{sub 1.05}Fe{sub 0.95}PO4 is a direct indication that the charge compensation for substitution of Fe{sup 2+} by Li{sup +} resides in the unoccupied O-2p orbitals. A charge transfer (CT) excitation was also observed in the doped material implying that the unoccupied O-2p orbitals created by doping are strongly hybridized with unoccupied Fe-3d orbitals of neighboring sites. However, the strong covalent bonding within the (PO{sub 4}){sup 3-} anions and the large separation of the Fe cations means that the charge created by doping is not delocalized in the manner of electrons or holes in a semiconductor.

Allen, J.L.; Zhuang, G.V.; Ross, P.N.; Guo, J.-H.; Jow, T.R.

2006-05-31

221

Diffusion of highly charged cations in olivine  

NASA Astrophysics Data System (ADS)

Diffusion of tungsten, titanium and phosphorus have been measured in natural iron-bearing olivine (~Fo90) and synthetic forsterite. Experiments were run under buffered conditions (with iron-wustite or Ni-NiO buffers) in 1-atm furnaces. The sources of diffusant for experiments were MgWO4 for tungsten diffusion, Mg2TiO4 for Ti diffusion, and AlPO4 for P diffusion; in all cases these compounds were pre-reacted at high temperature with Mg2SiO4 or Fe-bearing olivine prior to diffusion anneals. Samples were placed with the source materials in noble metal or silica capsules, which were sealed under vacuum in silica glass ampoules with solid buffers. Rutherford backscattering spectrometry (RBS) was used to measure depth profiles for all sets of experiments; measurements of P were also made with Nuclear Reaction Analysis using the 31P(?,p)34S reaction. These new data suggest marked differences among diffusivities of these cations, with titanium diffusion faster than diffusion of tungsten, but slower than diffusion of phosphorus over the conditions investigated. Diffusivities of all of these elements appear significantly slower than those of divalent cations in olivine. These results will be discussed in context with extant diffusion data for major, trace and minor elements in olivine. The effects of oxygen fugacity and olivine composition on diffusion, and potential implications for diffusion mechanisms will also be considered.

Cherniak, D. J.; Watson, E. B.; Liang, Y.

2012-12-01

222

Raman spectra of shocked minerals. I - Olivine  

NASA Technical Reports Server (NTRS)

The Raman spectra of olivine contained in a chip of the Twin Sisters Peak (Washington) dunite shocked to 22.2 GPa is shown to be identical to that of unshocked olivine in the same rock. The Raman spectra of powder of the rock shocked to 20.1 GPa and of chips shocked to 59.5 GPa and 60.7 GPa display strong and broad low-frequency features with crests at 475/cm, 556/cm, and 572/cm, and broad high-frequency features near 1100/cm. It is suggested that these features are due to the formation of olivine glass with a considerable degree of three-dimensional Si-O-Si linkage having scattered domains of greatly variable grain size, internal structure, and chemical composition.

Heymann, D.; Celucci, T. A.

1988-01-01

223

Zoning of phosphorus in igneous olivine  

Microsoft Academic Search

We describe P zoning in olivines from terrestrial basalts, andesites, dacites, and komatiites and from a martian meteorite.\\u000a P2O5 contents of olivines vary from below the detection limit (?0.01 wt%) to 0.2–0.4 wt% over a few microns, with no correlated\\u000a variations in Fo content. Zoning patterns include P-rich crystal cores with skeletal, hopper, or euhedral shapes; oscillatory\\u000a zoning; structures suggesting replacement of

Margaret S. Milman-Barris; John R. Beckett; Michael B. Baker; Amy E. Hofmann; Zachary Morgan; Meghan R. Crowley; Daniel Vielzeuf; Edward Stolper

2008-01-01

224

The origin of ferrous zoning in Allende chondrule olivines  

NASA Astrophysics Data System (ADS)

Very similar major and minor element compositions are noted in the ferrous olivine occurring in chondrules at olivine grain boundaries, along cracks in olivine grains, interleaved with enstatite, and in the inner portions of exposed olivine grain surface rims; simultaneous formation by a single process is therefore suggested. The ferrous chondrule olivine probably formed by the reaction of chondrules with very hot nebular vapors over a period of several hours, followed by the condensation of residual metal vapors onto those olivine surfaces that were in direct contact with the gas as the system cooled. The ferrous chondrule olivine that occurs interleaved with enstatite in Allende does not have a composition identical to, and is not the precursor of, matrix olivine.

Peck, J. A.; Wood, J. A.

1987-06-01

225

Shock Effects in Olivine from Mocs Chondrite  

NASA Astrophysics Data System (ADS)

The Mocs (syn. Moci) meteorite, classified as L6 chondrite by Van Schmus and Wood [1] and recently reclassified as L5-6 by Miura et al. [2], fell on February 3, 1882, 16.00 hrs. , over a large area (15 km by 3 km) in Transylvania (Cluj District). Olivine from six fragments of the Mocs chondrite was analyzed by optical microscopy, scanning electron microscopy with energy dispersive X-ray analysis and X-ray powder diffractometry. Olivine occurs as grains in matrix or chondrules: barred olivine chondrules, composed of parallel sets of prismatic olivine crystals and devitrified glass and porphyritic olivine chondrules, which consist mainly of fine-grained olivine crystals and glassy materials of feldspsr composition. In order to determine the mineralogical and chemical effects of shock metamorphism (induced by collisions in space of the Mocs chondrite parent body), in every thin section, ten to twenty of the largest, randomly distributed olivine single crystals were examined by optical polarizing microscope with 20X- or 40X- objectives [3] and with a JEOL JSM-5400 scanning electron microscope for higher magnifications. The mineralogical effects observed are: undulatory extinction, irregular fractures, planar fractures, mosaicism and planar deformation features. These, correlated with the presence of small amounts of maskelynite (An 12-19) indicate that the maximum shock degree this meteorite experienced was S-5 [3]. The quantitative chemical analysis of 77 olivine grains in matrix from all thin sections (6), determined by a JEOL JSM-5400 scanning electron microscope with JED 2001 energy dispersive X-ray analysis at the Yamaguchi University, shows a variation in composition from Fa23 to Fa27 mole % fayalite (Avg. Fa25; PMD 2.3%), indicative of the L-group. The Fayalite content of olivine from chondrules ranges from Fa23 to Fa27 (Avg. Fa25; PMD 1.74%). According to DEER et al. [4], olivine composition can be measured also by X-ray powder diffractometry as Fa (mol per cent) = 100-(4233.91-1494.59 x d130). By using a RIGAKU computer assisted-diffractometer (radiation Cu K alpha = 1.54059) at the Yamaguchi University, the d130 value of olivine from Mocs meteorite was calculated as 2.781 A and the fayalite content as Fa23 mole % fayalite (Forsterite-ferroan as of IMA files, 1993) consistent also with the L-group. The cell parameters and density determined from the X-ray diffraction pattern are: a=4.779; b=10.297; c=6.032; V=296.857 and Dx=3.446 g/cm3. References: [1] Van Schmus W. R. and Wood J. A. (1967) GCA, 31, 747-765. [2] Miura Y. et al. (1995) Proc. NIPR Symp. Antarct. Meteorites, 8, in press. [3] Stoffler D. et al. (1991) GCA, 55, 3845-3867. [4] Deer W. A. et al. (1992) 2nd edition, 4.

Iancu, O. G.; Miura, Y.; Iancu, G.

1995-09-01

226

Transmission electron microscopy of subsolidus oxidation and weathering of olivine  

USGS Publications Warehouse

Olivine crystals in basaltic andesites which crop out in the Abert Rim, south-central Oregon have been studied by high-resolution and analytical transmission electron microscopy. The observations reveal three distinct assemblages of alteration products that seem to correspond to three episodes of olivine oxidation. The olivine crystals contain rare, dense arrays of coherently intergrown Ti-free magnetite and inclusions of a phase inferred to be amorphous silica. We interpret this first assemblage to be the product of an early subsolidus oxidation event in the lava. The second olivine alteration assemblage contains complex ordered intergrowths on (001) of forsterite-rich olivine and laihunite (distorted olivine structure with Fe3+ charge balanced by vacancies). Based on experimental results for laihunite synthesis (Kondoh et al. 1985), these intergrowths probably formed by olivine oxidation between 400 and 800??C. The third episode of alteration involves the destruction of olivine by low-temperature hydrothermal alteration and weathering. Elongate etch-pits and channels in the margins of fresh olivine crystals contain semi-oriented bands of smectite. Olivine weathers to smectite and hematite, and subsequently to arrays of oriented hematite crystals. The textures resemble those reported by Eggleton (1984) and Smith et al. (1987). We find no evidence for a metastable phase intermediate between olivine and smectite ("M" - Eggleton 1984). The presence of laihunite exerts a strong control on the geometry of olivine weathering. Single laihunite layers and laihunite-forsteritic olivine intergrowths increase the resistance of crystals to weathering. Preferential development of channels between laihunite layers occurs where growth of laihunite produced compositional variations in olivine, rather than where coherency-strain is associated with laihunite-olivine interfaces. ?? 1990 Springer-Verlag.

Banfield, J. F.; Veblen, D. R.; Jones, B. F.

1990-01-01

227

Diffusive behavior in LiMPO4 with M=Fe, Co, Ni probed by muon-spin relaxation  

NASA Astrophysics Data System (ADS)

In order to study the diffusive nature of lithium transition-metal phospho-olivines, we measured muon-spin relaxation (?+SR) spectra for the polycrystalline LiMPO4 samples with M=Mn, Fe, Co, or Ni in the temperature range between 50 and 500 K. The ?+SR spectra under zero applied field are strongly affected by the magnetic moments of the 3d electrons in the M2+ ions so that, for LiMnPO4, it was difficult to detect the relaxation change caused by the diffusion due to the large Mn2+(S=5/2) moments. However, diffusive behavior was clearly observed via the relaxation due to nuclear dipolar fields above ˜150 K for LiFePO4, LiCoPO4, and LiNiPO4 as S decreased from 2 to 1. From the temperature dependence of the nuclear field fluctuation rate, self-diffusion coefficients of Li+ ions (DLi) at 300 K and its activation energy (Ea) were estimated, respectively, as ˜3.6(2)×10-10 cm2/s and Ea=0.10(2) eV for LiFePO4, ˜1.6(1)×10-10 cm2/s and Ea=0.10(1) eV for LiCoPO4, and ˜2.7(4)×10-10 cm2/s and Ea=0.17(2) eV for LiNiPO4, assuming that the diffusing Li+ ions jump between the regular site and interstitial sites.

Sugiyama, Jun; Nozaki, Hiroshi; Harada, Masashi; Kamazawa, Kazuya; Ikedo, Yutaka; Miyake, Yasuhiro; Ofer, Oren; Månsson, Martin; Ansaldo, Eduardo J.; Chow, Kim H.; Kobayashi, Genki; Kanno, Ryoji

2012-02-01

228

Electronically conductive phospho-olivines as lithium storage electrodes.  

PubMed

Lithium transition metal phosphates have become of great interest as storage cathodes for rechargeable lithium batteries because of their high energy density, low raw materials cost, environmental friendliness and safety. Their key limitation has been extremely low electronic conductivity, until now believed to be intrinsic to this family of compounds. Here we show that controlled cation non-stoichiometry combined with solid-solution doping by metals supervalent to Li+ increases the electronic conductivity of LiFePO4 by a factor of approximately 10(8). The resulting materials show near-theoretical energy density at low charge/discharge rates, and retain significant capacity with little polarization at rates as high as 6,000 mA x g(-1). In a conventional cell design, they may allow development of lithium batteries with the highest power density yet. PMID:12618828

Chung, Sung-Yoon; Bloking, Jason T; Chiang, Yet-Ming

2002-10-01

229

A general solution-chemistry route to the synthesis Li MPO 4 ( M=Mn, Fe, and Co) nanocrystals with [010] orientation for lithium ion batteries  

Microsoft Academic Search

A general and efficient solvothermal strategy has been developed for the preparation of lithium transition metal phosphate microstructures (LiMnPO4, LiFePO4, and LiCoPO4), employing ethanol as the solvent, LiI as the Li source, metal salts as the M sources, H3PO4 as the phosphorus source, and poly(vinyl pyrrolidone) (PVP) as the carbon source and template. This route features low cost, environmental benign,

Jing Su; Bing-Qing Wei; Jie-Peng Rong; Wen-Yan Yin; Zhi-Xia Ye; Xian-Qing Tian; Ling Ren; Min-Hua Cao; Chang-Wen Hu

2011-01-01

230

Low temperature preparation of optimized phosphates for Li-battery applications  

Microsoft Academic Search

We describe the thermodynamics and kinetics that govern the precipitation of pure powders of phosphates phases of interest for Li-battery applications. We found precise procedures for the formation of three distinct crystalline forms of FePO4·2H2O and of pure LiMnPO4. Our attempts to precipitate either LiCoPO4 or LiFePO4, on the other hand, failed. In this latter case, optimized electrodes for battery

Charles Delacourt; Calin Wurm; Priscilla Reale; Mathieu Morcrette; Christian Masquelier

2004-01-01

231

Trace-Element Diffusion Coefficients in Olivine  

NASA Astrophysics Data System (ADS)

We have undertaken chemical diffusion experiments at 1300°C to determine both crystal/melt partition coefficients and diffusion coefficients for a wide range of trace elements in forsteritic olivine. Experiments were conducted at 1 atm under controlled fO2 for up to 25 days using synthetic melts made to a composition in equilibrium with olivine for major elements, and doped with selected trace elements. The melt was put into a 5 mm diameter cylindrical hole in gem quality San Carlos olivine crystals drilled paralell to the a axis. Diffusion profiles were obtained both for trace elements that were added to the starting material and diffuse into the olivine, and also for several trace elements present at natural abundances in the olivine that diffuse out. The profiles were measured across sections perpendicular to crystal/melt boundary at a variety of crystallographic orientations (confirmed by EBSD) by laser-ablation ICP-MS. A thin laser slit oriented parallel to the crystal/melt interface was traversed from the melt through the crystal. Element concentrations were fitted to the diffusion equation to obtain both diffusion coefficients and concentrations at the crystal/melt interface, and hence partition coefficients. Calculated diffusivities for many trace elements (Ca, REE, Y, Sc, V, Cr, Ni, Co, Mn, Na, Li, Be, Ti) are relatively fast (D = 10-16 to 10^{-13 m2/s at 1300°C). The diffusion of Li in olivine (approx. D = 10^{-15} m2/s) is only slightly slower than REEs and similar to divalent cations, in good agreement with inferences from zoning profiles in natural olivine [1]. This rate is considerably slower than for plagioclase and clinopyroxene [2], a result which has important implications for interpreting Li isotopic data from mantle-derived rocks. The fastest diffusing trace element we observe is Be. Applying our diffusion and partition coefficients to the model of Qin et al. [3], we calculate that the REEs of olivine-hosted melt inclusions in the mantle will extensively re-equilibrate with external magma in weeks (heavy REEs) to a few years (light REEs). These timescales are significantly shorter than the times estimated for the production and extraction of magma from the mantle or magma residence in the lower crust, implying anomalous melt inclusions are probably not a direct result of melting of heterogeneities in the mantle. Instead, anomalous melt inclusions likely form by assimilation processes shortly before eruption [4] and so may be useful monitors of such processes. Refs: [1] Parkinson et al., Abstract, Goldschmidt Conference 2006; [2] Coogan et al., EPSL 240, 415-424 (2005); [3] Qin et al. Am. Min. 77, 565-576 (1992); [4] Danyushevsky et al., J. Petrol. 45, 2531-2553 (2004).

Spandler, C.; O'Neill, H. S.

2006-12-01

232

Mechanisms of electrical conductivity in olivine  

SciTech Connect

Data on the electrical conductivity and the thermoelectric effect in single crystals indicate that the charge conduction mechanism in pure magnesium forsterite is electrons. The concentration of electrons can be varied by controlling the number of oxygen vacancies through manipulation of the oxygen pressure. For iron bearing olivine, the conduction mechanism is by electron holes localized on an iron ion. Since iron strongly affects the creep process as well, oxidation of iron is probably accompanied by the production of magnesium vacancies. 15 references.

Schock, R.N.; Duba, A.G.; Shankland, T.J.

1984-01-01

233

Dislocation creep of fine-grained olivine  

Microsoft Academic Search

Deformation experiments conducted in a gas medium apparatus at temperatures from 1200 to 1350°C with a fine-grained, solution-gelation derived Fe-bearing olivine show a stress dependence of the strain rate at stresses above ?150 MPa, which is much stronger than previously reported for polycrystalline samples. The data can be fit by a power law with $\\\\dot {\\\\epsilon }$$\\\\propto$?n with n ?

U. H. Faul; J. D. Fitz Gerald; R. J. M. Farla; R. Ahlefeldt; I. Jackson

2011-01-01

234

Water and Carbon Dioxide Adsorption at Olivine Surfaces  

SciTech Connect

Plane-wave density functional theory (DFT) calculations were performed to simulate water and carbon dioxide adsorption at the (010) surface of five olivine minerals, namely, forsterite (Mg2SiO4), calcio-olivine (Ca2SiO4), tephroite (Mn2SiO4), fayalite (Fe2SiO4), and Co-olivine (Co2SiO4). Adsorption energies per water molecule obtained from energy minimizations varied from -78 kJ mol-1 for fayalite to -128 kJ mol-1 for calcio-olivine at sub-monolayer coverage and became less exothermic as coverage increased. In contrast, carbon dioxide adsorption energies at sub-monolayer coverage ranged from -20 kJ mol-1 for fayalite to -59 kJ mol-1 for calcio-olivine. Therefore, the DFT calculations show a strong driving force for carbon dioxide displacement by water at the surface of all olivine minerals in a competitive adsorption scenario. Additionally, adsorption energies for both water and carbon dioxide were found to be more exothermic for the alkaline-earth (AE) olivines than for the transition-metal (TM) olivines and to not correlate with the solvation enthalpies of the corresponding divalent cations. However, a correlation was obtained with the charge of the surface divalent cation indicating that the more ionic character of the AE cations in the olivine structure relative to the TM cations leads to greater interactions with adsorbed water and carbon dioxide molecules at the surface and thus more exothermic adsorption energies for the AE olivines. For calcio-olivine, which exhibits the highest divalent cation charge of the five olivines, ab initio molecular dynamics simulations showed that this effect leads both water and carbon dioxide to react with the surface and form hydroxyl groups and a carbonate-like species, respectively.

Kerisit, Sebastien N.; Bylaska, Eric J.; Felmy, Andrew R.

2013-11-14

235

Search for Olivine Spectral Signatures on the Surface of Vesta  

NASA Technical Reports Server (NTRS)

The occurrence of olivines on Vesta were first postulated from traditional petrogenetic models which suggest the formation of olivine as lower crustal cumulates. An indirect confirmation is given by their presence as a minor component in some samples of diogenite meteorites, the harzburgitic diogenites and the dunitic diogenites, and as olivine mineral clasts in howardites. Another indication for this mineral was given by interpretations of groundbased and Hubble Space Telescope observations that suggested the presence of local olivine-bearing units on the surface of Vesta. The VIR instrument onboard the DAWN mission has been mapping Vesta since July 2011. VIR acquired hyperspectral images of Vesta s surface in the wavelength range from 0.25 to 5.1 m during Approach, Survey and High Altitude Mapping (HAMO) orbits that allowed a 2/3 of the entire asteroid surface to be mapped. The VIR operative spectral interval, resolution and coverage is suitable for the detection and mapping of any olivine rich regions that may occur on the Vesta surface. The abundance of olivine in diogenites is typically lower than 10% but some samples richer in olivine are known. However, we do not expect to have extensive exposures of olivine-rich material on Vesta. Moreover, the partial overlap of olivine and pyroxene spectral signatures will make olivine difficult to detect. Different spectral parameters have been used to map olivine on extraterrestrial bodies, and here we discuss the different approaches used, and develop new ones specifically for Vesta. Our new methods are based on combinations of the spectral parameters relative to the 1 and 2 micron bands (the most prominent spectral features of Vesta surface in the visible and the infrared), such as band center locations, band depths, band areas, band area ratios. Before the direct application to the VIR data, the efficiency of each approach is evaluated by means of analysis of laboratory spectra of HED meteorites, pyroxenes, olivines and their mixtures.

Palomba, E.; De Sanctis, M. C.; Ammannito, E.; Capaccioni, F.; Capria, M. T.; Farina, M.; Frigeri, A.; Longobardo, A.; Tosi, F.; Zambon, F.; McSween, H. Y.; Mittlefehldt, D. W.; Russell, C. T.; Raymond, C. A.; Sunshine, J.; McCord, T. B.

2012-01-01

236

Olivine diogenites - The mantle of the eucrite parent body  

NASA Technical Reports Server (NTRS)

Two olivine-rich Antarctic diogenites (ALH A77256 and ALH 84001) of the howardite-eucrite-diogenite (HED) meteorite association have olivine/pyroxene ratios similar to normative ratios in devolatilized ordinary chondrites. Based on chemical data and petrological analysis, these meteorites represent the residuum of partial melting of the mantle in the eucrite parent body (EPB). Mineral assemblages in these olivine-rich diogenites record a continuum in thermal histories from initial partial melting (1150-1200 C) to subsolidus reequilibration (795 + or - 55 C). The small number of olivine-rich diogenites known hints that only the outer portion of the EPB has been sampled.

Sack, Richard O.; Azeredo, William J.; Lipschutz, Michael E.

1991-01-01

237

Discovery of Olivine in the Nili Fossae Region of Mars  

USGS Publications Warehouse

We have detected a 30,000-square-kilometer area rich in olivine in the Nili Fossae region of Mars. Nili Fossae has been interpreted as a complex of grabens and fractures related to the formation of the Isidis impact basin. We propose that post-impact faulting of this area has exposed subsurface layers rich in olivine. Linear mixture analysis of Thermal Emission Spectrometer spectra shows surface exposures of 30% olivine, where the composition of the olivine ranges from Fo30 to Fo70.

Hoefen, T. M.; Clark, R. N.; Bandfield, J. L.; Smith, M. D.; Pearl, J. C.; Christensen, P. R.

2003-01-01

238

Anisotropic and Isotropic Effective Olivine Medium Models  

NASA Astrophysics Data System (ADS)

New experimental techniques are used to accurately measure the electrical conductivity (?) of single crystal San Carlos olivine (Fo89.1) along each principal orientation. The temperature (1100, 1200, and 1300°C) and oxygen fugacity (10-7olivine medium for each principle orientation, suitable for use over the upper mantle temperature range and a range of oxygen buffer assemblages. A [100]-lattice preferred oriented layer of dry olivine would provide a maximum of ~100.5 S/m azimuthal conductivity contrast for T = 1500°C. The anisotropic results are combined to create an isotropic model with steady-state fO2-independent Ea = 0.53 eV. The inclusion of the ?min results in conductivity that is ~0.6 log units higher than the previous SO1 and SO2 models for T = 1000°C. The difference between this model and the previous SO1 and SO2 models become larger with decreasing T. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under contract W-7405-ENG-48 and supported specifically by Laboratory Directed Research and Development funding.

Du Frane, W. L.; Tyburczy, J. A.; Roberts, J. J.; Toffelmier, D. A.

2005-12-01

239

Kinetics of intracrystalline olivine-ringwoodite transformation  

NASA Astrophysics Data System (ADS)

We studied the microstructural evolution and kinetics of intracrystalline olivine-ringwoodite transformation in order to evaluate the importance of this mechanism in subducting lithosphere. Intracrystalline transformation occurs within single crystals of San Carlos olivine (Fo 90) at T?900°C and P?18 GPa and involves four stages: (1) Formation of (100) ? stacking faults in olivine, (2) coherent nucleation of thin ringwoodite platelets on these stacking faults, (3) semi-coherent growth of the platelets and (4) incoherent nucleation of ringwoodite and/or wadsleyite grains at the platelet interfaces. Because rates of incoherent growth are about two orders of magnitude faster than rates of semi-coherent growth, the final stage is most important for bulk transformation. However, the ringwoodite platelets act as essential nucleation sites for intracrystalline incoherent transformation. The growth of ringwoodite platelets proceeds by the nucleation and migration of interface ledges (1.0-1.5 nm high) and is thermally activated with an activation energy of ˜270 kJ mol -1. This is similar to the activation energy for incoherent growth, suggesting that both processes are controlled by Si?O bond breaking. The nucleation rate of platelets, as determined from the densities of platelets observed in transmission electron microscopy (TEM) sections, is also strongly temperature-dependent and has a similar activation energy. These results suggest that intracrystalline transformation is likely to be important in subducting lithosphere in addition to the grain boundary nucleation mechanism. The intracrystalline mechanism will reduce the depth interval over which the transformation occurs and may enhance rheological weakening by reducing the grain size of the reaction products.

Kerschhofer, L.; Rubie, D. C.; Sharp, T. G.; McConnell, J. D. C.; Dupas-Bruzek, C.

2000-09-01

240

Olivine Annealing in Molten Iron-Sulfide. A Tool to Interpret the Origin of Pallasites  

NASA Astrophysics Data System (ADS)

Annealing of olivine in molten Fe-S was performed in order to decipher the origin of rounded olivine group pallasite meteorites. Growth mechanism and growth rate of olivine was obtained and a variety of formation models are critically discussed.

Solferino, G. F. D.; Muir, S. L.

2013-09-01

241

Compositions of Partly Altered Olivine and Replacement Serpentine in the CM2 Chondrite QUE 93005  

NASA Astrophysics Data System (ADS)

Serpentine replacing olivine in QUE 93005 has a narrow range of compositions, regardless of the reactant olivine’s composition. Homogeneity of replacement serpentines in QUE 93005 and other CM2s favors homogeneity of aqueous solutions on >cm scales.

Velbel, M. A.; Tonui, E. K.; Zolensky, M. E.

2013-09-01

242

Olivine in an unexpected location on Vesta's surface.  

PubMed

Olivine is a major component of the mantle of differentiated bodies, including Earth. Howardite, eucrite and diogenite (HED) meteorites represent regolith, basaltic-crust, lower-crust and possibly ultramafic-mantle samples of asteroid Vesta, which is the lone surviving, large, differentiated, basaltic rocky protoplanet in the Solar System. Only a few of these meteorites, the orthopyroxene-rich diogenites, contain olivine, typically with a concentration of less than 25 per cent by volume. Olivine was tentatively identified on Vesta, on the basis of spectral and colour data, but other observations did not confirm its presence. Here we report that olivine is indeed present locally on Vesta's surface but that, unexpectedly, it has not been found within the deep, south-pole basins, which are thought to be excavated mantle rocks. Instead, it occurs as near-surface materials in the northern hemisphere. Unlike the meteorites, the olivine-rich (more than 50 per cent by volume) material is not associated with diogenite but seems to be mixed with howardite, the most common surface material. Olivine is exposed in crater walls and in ejecta scattered diffusely over a broad area. The size of the olivine exposures and the absence of associated diogenite favour a mantle source, but the exposures are located far from the deep impact basins. The amount and distribution of observed olivine-rich material suggest a complex evolutionary history for Vesta. PMID:24196707

Ammannito, E; De Sanctis, M C; Palomba, E; Longobardo, A; Mittlefehldt, D W; McSween, H Y; Marchi, S; Capria, M T; Capaccioni, F; Frigeri, A; Pieters, C M; Ruesch, O; Tosi, F; Zambon, F; Carraro, F; Fonte, S; Hiesinger, H; Magni, G; McFadden, L A; Raymond, C A; Russell, C T; Sunshine, J M

2013-12-01

243

Dynamic recrystallization and grain growth in olivine rocks  

Microsoft Academic Search

A mechanism based description of the rheology of olivine is essential for modeling of upper mantle geodynamics. Previously, mantle flow has been investigated using flow laws for grain size insensitive (GSI) dislocation creep and\\/or grain size sensitive (GSS) diffusion creep of olivine. Generally, flow laws have been calibrated in experiments to relatively low strains. Recenty, however, it has become apparent

A. Kellermann Slotemaker

2006-01-01

244

Ringwoodite lamellae in olivine: Clues to olivine-ringwoodite phase transition mechanisms in shocked meteorites and subducting slabs  

PubMed Central

The first natural occurrence of ringwoodite lamellae was found in the olivine grains inside and in areas adjacent to the shock veins of a chondritic meteorite, and these lamellae show distinct growth mechanism. Inside the veins where pressure and temperature were higher than elsewhere, ringwoodite lamellae formed parallel to the {101} planes of olivine, whereas outside they lie parallel to the (100) plane of olivine. The lamellae replaced the host olivine from a few percent to complete. Formation of these lamellae relates to a diffusion-controlled growth of ringwoodite along shear-induced planar defects in olivine. The planar defects and ringwoodite lamellae parallel to the {101} planes of olivine should have been produced in higher shear stress and temperature region than that parallel to the (100) plane of olivine. This study suggests that the time duration of high pressure and temperature for the growth of ringwoodite lamellae might have lasted at least for several seconds, and that an intracrystalline transformation mechanism of ringwoodite in olivine could favorably operate in the subducting lithospheric slabs in the deep Earth.

Chen, Ming; Goresy, Ahmed El; Gillet, Philippe

2004-01-01

245

Mineralogy of interplanetary dust particles from the 'olivine' infrared class  

NASA Technical Reports Server (NTRS)

Analytical electron microscopy observations establish that olivine is abundant and the predominant silicate phase in three interplanetary dust particles (IDPs) from the 'olivine' infrared spectra category. Two of the particles have microstructures resembling those of most nonhydrous chondritic IDPs, consisting of micron to submicron grains together with a matrix composed of amorphous carbonaceous material and sub-500 A grains. In addition to olivine these particles respectively contain enstatite and magnetite, and pentlandite plus Ca-rich clinopyroxene. The third IDP consists mostly of olivine and pyrrhotite with little or no matrix material. Olivine grains in this particle contain prominent solar-flare ion tracks with densities corresponding to a space-exposure age between 1000 to 100,000 years. Although the three particles have olivine-rich mineralogies in common, other aspects of their mineralogies and microstructures suggest that they experienced different formation histories. The differences between the particles indicate that the olivine infrared spectral category is a diverse collection of IDPs that probably incorporates several genetic groups.

Christoffersen, R.; Buseck, P. R.

1986-01-01

246

Heterogeneous distribution of Fe in olivine grains generated by serpentinization  

NASA Astrophysics Data System (ADS)

We investigated Fe-rich stripes developed within olivine crystals composed of serpentinized peridotites which were obtained at Conical seamount in the Mariana forearc. Modal analyses of primary minerals and their serpentinized pseudomorphs indicate that the protoliths of the peridotites are harzburgite and dunite. They are composed of serpentine minerals, acicular diopside, olivine, magnetite, and rare brucite as metamorphic minerals, and olivine, diopside, and chromian spinel as primary minerals. Chrysotile and/or lizardite are main serpentine minerals, but antigorite is widely distributed in the samples. Forsterite composition of the olivine is Fo90-92. Fe-rich stripes with ca. 5 um width are well developed within the olivine crystals. The distribution of the Fe-rich stripes is restricted only at the area contacted with antigorite. TEM samples made using the Focused Ion Beam system indicate clearly that the Fe-rich stripes are created on the dislocation arrays making (100) sub-grain boundaries. Forsterite composition on the dislocation arrays measured by ATEM and EPMA is ca. 88 mol%. These facts can be explained by interdiffusion between Mg and Fe along the dislocation core during serpentinization after ceasing plastic deformation of olivines. The origin of high Fe composition is probably olivine itself, because the antigorite formation causes an extra Fe. This phenomenon is much important to understand the behavior of fluid and composition during serpentinization.

Ando, J.; Ohfuji, H.; Urata, Y. M.; Murata, K.; Maekawa, H.

2009-12-01

247

Experimental petrology of meteorites: Phosphorus and oxygen isotopes in olivine  

NASA Astrophysics Data System (ADS)

Experiments have been conducted to investigate the exchange and behavior of phosphorus and oxygen isotopes in olivine of extraterrestrial materials. The first project concentrated on determining the conditions necessary for the formation of phosphoran olivine in pallasite meteorites. Results indicate that phosphoran olivine forms during rapid crystallization and not subsolidus diffusion. Phosphoran olivine does not persist if the system closely approaches equilibrium. Models proposing that pallasites represent samples of a core- mantle boundary of a differentiated asteroid are inconsistent with these results. The second and third projects involved the exchange of oxygen isotopes in chondrules at nebular pressures and temperatures, first observing gas-melt exchange, then olivine-melt exchange. In the gas-melt exchange experiments, a low pressure flow of carbon monoxide gas was reacted with an olivine-normative melt to simulate exchange with a nebular gas in the early solar system. No isotopic exchange between carbon monoxide and olivine-rich melt was detected. However, the experiments did demonstrate for the first time, the kinetic evaporation of oxygen. It was proposed that water vapor was likely the major oxygen-bearing species to exchange oxygen in the early solar nebula and carbon monoxide contributed to this only through reactions with the water vapor or ambient hydrogen. The final experiments involved exchange of oxygen between relict chondrule olivine, their overgrowths, and the chondrule melt. It was determined that Fe-Mg diffusion can obscure relict grains during chondrule crystallization. However, the original oxygen isotopic composition of those grains will remain intact. Durations of weeks at high temperature are required to obscure the oxygen signature by diffusion. Relict olivine grains are more prevalent than previously estimated and probably occur in more than 30% of all chondrules.

Boesenberg, Joseph S.

248

The case for a cognate, polybaric origin for kimberlitic olivines  

NASA Astrophysics Data System (ADS)

Kimberlitic olivines typically show a continuous range in size and texture rather than two discrete populations. The cores of small euhedral olivines commonly provide the template for the final crystal shape, which in turn closely matches morphologies produced by crystallization from a moderately under-cooled magma. Cores and edges of the majority of all olivines define a continuous compositional field, which can be interpreted in terms of Raleigh crystallization. Marked chemical gradients at the olivine margins are linked to rapid physico-chemical changes to the magma associated with loss of volatiles during the late stages of emplacement. Thus, rapid crystallization of groundmass olivines would deplete the magma in Ni, but increase Ca activity. The latter would be enhanced by decreasing pressure coupled with loss of CO 2 from the carbonate-bearing kimberlite magma. For mantle olivines and the most refractory olivines in kimberlites (~ Fo 94) to be in equilibrium with bulk rock compositions matching those of Mg-rich macrocrystic and aphanitic kimberlites (Mg# ~ 88) requires a mineral-melt Mg-Fe distribution coefficient of 0.47. This is well within the experimentally determined range for this distribution coefficient in carbonate-bearing systems. In southern African post-Gondwana alkaline pipe clusters, the average bulk rock Mg# and composition of the associated most Mg-rich olivine both decrease sympathetically from the interior to the continental margin, which is also consistent with a cognate origin for the olivines. A kimberlite magma following a plausible P-T trajectory relative to the CO 2/H 2O peridotite solidus would initially experience superheating, resulting in partial resorption of early-formed olivines that crystallized on the cool conduit walls. It would become supersaturated as it crossed the carbonated peridotite "ledge", resulting in tabular and hopper growth forms typical of euhedral olivine cores. With further ascent, the magma would once again become superheated, resulting in partial resorption of these cores. Thus, apparently complex textures and internal zonation patterns of kimberlitic olivines are predicted by a plausible magma P-T trajectory.

Moore, Andy E.

2012-01-01

249

Olivines from Kimberlites and Diamonds: Problem of Origin  

NASA Astrophysics Data System (ADS)

Mg-rich olivine Fo [100Mg/(Mg + Fe)] 85-94 is the principal mineral of kimberlites, peridotite xenoliths and diamond inclusions. It is completely altered in common kimberlites, however, it is absolutely fresh in a huge block from Udachnaya-East kimberlite in Yakutia (Russia). Pioneering studies of this unaltered kimberlite resulted in a discovery of high role of a mantle chlorine along with very low water content (Kamenetsky et al., 2004, Geology, 32: 845-848). Two olivine populations are distinguished, which are represented by oval-rounded unzoned or partly zoned xenocrysts of olivine I (more than 1 mm) and well defined zoned phenocrysts ( 0.05-1.0 mm) of olivine II (e.g. Kamenetsky et al., 2008, J.Petrol., 49: 823-839). The cores of olivine II are compositionally similar to olivine I with Mg# 86-94, but rims of olivine II and partly preserved rims of olivine I have constant Fo values about 89-90. We report here the results of major and minor elements analyses by EPMA of more than 300 grains of olivine I and olivine II, both of cores and rims by high precision approach (Sobolev et al., 2007, Science, 316: 412-417) to minor elements including Ti, Al, Cr, Ca, Mn, Ni, Co using the high sample current and high counting time, which was found optimal to obtain limit of detection about 10 ppm. Several grains of analyzed olivines contain clinopyroxene (cpx) and pyrope (prp) inclusions confirming their high pressure origin. One large olivine I grain contains clusters of cpx ( 33 grains) and prp ( 6 grains) inclusions., having a range in Cr2O3 (1.52- 2.36 wt%) , Al2O3 (0.99-5.53 wt%) and Na2O (1.45-5.96 wt%) for cpx and Cr2O3 (3.51-4.42 wt%) and CaO (5.64-6.61 wt%) for prp, showing disequilibrium in olivine I core, containing 200 ppm Ti. This is completely different from any peridotite xenoliths, confirming the uniqueness of this assemblage. The systematic high Ti ( more than 150 ppm) of all studied cores of olivine grains containing low T (Ca# 43.3-48) cpx and prp inclusions confirm the listed differences from all olivines from peridotites and diamonds (e.g. Sobolev et al., 2009, Lithos, 112S: 701-713.). Earlier, similar Ti abundance was reported only for olivines from dunite nodules in Greenland kimberlites (e.g. Arndt et al., 2010, J. Petrol., 51: 573-602).We suggest that Ti-bearing olivine, represented more that 70% of studied samples, is a part of high pressure pyrope lherzolite assemblage, which was formed and grew during the formation and early evolution of kimberlites

Sobolev, N. V.; Sobolev, A. V.; Tomilenko, A. A.; Kovyazin, S. V.; Kuzmin, D. V.

2011-12-01

250

Systematics of Vanadium in Olivine from Planetary Basalts  

NASA Technical Reports Server (NTRS)

The systematics of vanadium in olivines from the Earth, Moon and Mars allows for the comparison of planetary basalt origin and igneous setting and process. Additional information is contained in the original extended abstract.

Karner, J. M.; Papike, J. J.; Shearer, C. K.

2002-01-01

251

Olivine diogenites: The mantle of the eucrite parent body  

SciTech Connect

Two olivine-rich Antarctic diogenites (ALH A77256 and ALH 84001) of the howardite-eucritediogenite (HED) meteorite association have olivine/pyroxene ratios similar to normative ratios in devolatilized ordinary chondrites. Based on chemical data and petrological analysis, these meteorites represent the residuum of partial melting of the mantle in the eucrite parent body (EPB). Mineral assemblages in these olivine-rich diogenites record a continuum in thermal histories from initial partial melting (1150-1200{degree}C) to subsolidus re-equilibration (795 {plus minus} 55{degree}C). The small number of olivine-rich diogenites known hints that only the outer portion of the EPB has been sampled.

Sack, R.O.; Azeredo, W.J.; Lipschutz, M.E. (Purdue Univ., IN (USA))

1991-04-01

252

Olivine and Pyroxene Compositions in Fine-Grained Chondritic Materials  

NASA Technical Reports Server (NTRS)

Our analyses of the Wild-2 samples returned by the Stardust Mission have illuminated critical gaps in our understanding of related astromaterials. There is a very large database of olivine and low-calcium pyroxene compositions for coarse-grained components of chondrites, but a sparse database for anhydrous silicate matrix phases. In an accompanying figure, we present comparisons of Wild-2 olivine with the available chondrite matrix olivine major element data. We thus have begun a long-term project measuring minor as well as major element compositions for chondrite matrix and chondritic IDPs, and Wild 2 grains. Finally, we wish to re-investigate the changes to fine-grained olivine and low-Ca pyroxene composition with progressive thermal metamorphism. We have examined the LL3-4 chondrites which because of the Hayabusa Mission have become very interesting.

Zolensky, Michael E.; Frank, D.

2011-01-01

253

Thermo-Reflectance Spectra of Eros: Unambiguous Detection of Olivine  

NASA Technical Reports Server (NTRS)

Olivine is readily detected on 433 Eros using the new thermo-reflectance spectral technique applied to near-IR spectra obtained at Eros by the NEAR spacecraft. Additional information is contained in the original extended abstract.

Lucey, P. G.; Hinrichs, J. L.; Urquhart-Kelly, M.; Wellnitz, D.; Bell, J. F., III; Clark, B. E.

2001-01-01

254

Olivine Weathering: Abiotic Versus Biotic Processes as Possible Biosignatures  

NASA Technical Reports Server (NTRS)

A preliminary study to determine how abiotic versus biotic processes affect the weathering of olivine crystals. Perhaps the differences between these weathering processes could be used as biosignatures. Additional information is contained in the original extended abstract.

Longazo, T. G.; Wentworth, S. J.; McKay, D. S.; Southam, G.; Clemett, S. J.

2001-01-01

255

Aluminum speeds up the hydrothermal alteration of olivine  

NASA Astrophysics Data System (ADS)

The reactivity of ultramafic rocks toward hydrothermal fluids controls chemical fluxes at the interface between the internal and external reservoirs of silicate planets. On Earth, hydration of ultramafic rocks is ubiquitous and operates from deep subduction zones to shallow lithospheric environments where it considerably affects the physical and chemical properties of rocks and can interact with the biosphere. This process also has key emerging societal implications, such as the production of hydrogen as a source of carbon-free energy. To date, the chemical model systems used to reproduce olivine hydrothermal alteration lead to the formation of serpentine with sluggish reaction rates. Although aluminum is common in geological environments and in hydrothermal systems in particular, its role in serpentinization or olivine dissolution has not been investigated under hydrothermal conditions. Nevertheless, abundant Al supply is expected in fluids released from dehydration of metapelites in subduction zones as well as during the hydrothermal alteration of gabbros at mid-ocean ridges. Aluminum was also abundant in primitive environments of both the Earth and Mars, stored in either Al-rich minerals like plagioclase or Al-enriched ultramafic lavas. We have investigated the role of Al on the hydrothermal alteration of olivine in a series of experiments performed in a low-pressure diamond anvil cell while following the reaction progress in situ by optical imaging and Raman spectroscopy. Experiments were run for 4.5 to 7.5 days with two olivine grains reacted in saline water (0.5 molal NaCl) at 200°C and 300°C, and P=200 MPa. After two days, olivine crystals were fully transformed to an aluminous serpentine, also enriched in iron. The presence of Al in the hydrothermal fluid increases the rate of olivine serpentinization by more than one order of magnitude by enhancing olivine solubility and serpentine precipitation. The mechanism responsible for this increased solubility has to be further investigated but this result motivates a re-evaluation of the natural rates of olivine serpentinization and of olivine hydrolysis in general in a wide range of settings where olivines or peridotites are intimately associated with Al-providers. Such a fast reaction rate may affect the contribution of reaction-enhanced processes at the micrometer-scale, such as reaction-driven cracking, already proposed for enhancing serpentinization or carbonation of olivine. The effect of Al on lower crust and upper mantle metasomatism is expected to be even stronger at higher pressure in subduction zones where those reactions control the rheology and physical properties of the subducting plate and mantle wedge.

Andreani, Muriel; Daniel, Isabelle; Pollet-Villard, Marion

2014-05-01

256

Dissolution of olivine in basaltic liquids: experimental observations and applications.  

USGS Publications Warehouse

Rates of olivine dissolution in synthetic lunar basalt 77115 and a silica-enriched 77115 composition (Sil-77115) at superliquidus temperatures have been determined. Dissolution-rate data have been applied to the problem of the thermal history of fragment-laden impact-melt rocks of the lunar highlands. Textural and chemical criteria are discussed for the recognition of olivine resorption (and growth) phenomena in igneous rocks. -J.A.Z.

Thornber, C. R.; Huebner, J. S.

1985-01-01

257

Olivine and Pyroxene Diversity in the Crust of Mars  

Microsoft Academic Search

Data from the Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) on the Mars Express spacecraft identify the distinct mafic, rock-forming minerals olivine, low-calcium pyroxene (LCP), and high-calcium pyroxene (HCP) on the surface of Mars. Olivine- and HCP-rich regions are found in deposits that span the age range of geologic units. However, LCP-rich regions are found only in

J. F. Mustard; F. Poulet; A. Gendrin; J.-P. Bibring; Y. Langevin; B. Gondet; N. Mangold; G. Bellucci; F. Altieri

2005-01-01

258

Thermal Emission Spectroscopy of 1 Ceres: Evidence for Olivine  

NASA Technical Reports Server (NTRS)

Thermal emission spectra of the largest asteroid 1 Ceres obtained from the Kuiper Airborne Observatory display features that may provide information on its surface mineralogy. A plot of the Ceres spectrum (calibrated using alpha Boo as a standard) divided by a standard thermal model (STM) is shown. Also shown is the emissivity spectrum deduced from reflectivity measurements for olivine grains <5 microns in diameter. The general shape of the Ceres and the olivine curves agree in essential details, such as the maxima from 8 to 12 microns, the minimum between 12 and 14 microns, the broad peak near 17.5 micron, and the slope beyond 22 micron. (Use of the 10 to 15-micron grain reflectivities provides a better match to the 12- to 14-micron dip. We used a value of unity for beta, the beaming factor associated with small-scale surface roughness in our STM. Adjustment of beta to a lower value raises the long-wavelength side of the Ceres spectrum, providing an even better match to the olivine curve.) The emissivity behavior roughly matches the emission coefficients which were calculated for olivine particles with a particle radius of 3 microns. Their calculations show not only the negative slope from 23 to 25 pm, but a continued decrease past 30 micron. The Ceres emissivity is thus similar to that of small olivine grains from 8 to 30 micron, but olivine's emissivity is lower from 5 to 8 pm.

Witteborn, F. C.; Roush, T. L.; Cohen, M.

1999-01-01

259

Kinetics of intracrystalline cation redistribution in olivine and its implication  

NASA Astrophysics Data System (ADS)

The rate of cation redistribution between M 1 and M 2 sites in olivine is theoretically studied on the basis of elementary processes of cationic migration. Cationic migration in olivine structure is assumed to be the superposition of a unit exchange of cations between closely spaced couple of sites. Such a process gives rise to both cation redistribution and also cationic interdiffusion in olivine crystal. The time constant of cationic equilibration in the redistribution reaction is related to the interdiffusion coefficient along b-axis, and its numerical value is given as a function of temperature and composition in Mg-Fe olivine. This time constant is very short, e.g., in the order of 10-2˜10-4 s at 1000 ° C. The temperature dependence of cation distribution in Mg-Fe olivine could not be detected by heating and quenching experiments in some previous works, because of insufficient cooling rate. A skepticism is presented for the utility of cation distribution as a geothermometer or rate meter of cooling. Cation redistribution in olivine in the deep upper mantle is sufficiently fast to take place almost in phase with the seismic waves of long periods.

Akamatsu, Tadashi; Kumazawa, Mineo

1993-02-01

260

Tracing Oxygen Fugacity in Asteroids and Meteorites Through Olivine Composition  

NASA Technical Reports Server (NTRS)

Olivine absorptions are known to dominate telescopic spectra of several asteroids. Among the meteorite collection, three groups (excluding Martian meteorites), the pallasites, brachinites, and R group chondrites are plausible analogs to olivine-rich asteroids in that they are dominated by olivine. These meteorite groups have distinct petrologic origins. The primitive achondrite brachinites (which include both depleted and undeleted subgroups) are products of relatively minor differentiation and evolved in oxidizing environments. R chondrites are also thought to have formed in high oxygen states, but are closely related to ordinary chondrites (yet with their own distinct compositions and oxygen isotopic signatures). In contrast, pallasites, widely thought to be mantle components from much more evolved bodies, formed in more reducing environments. Petrologic indicators that are identifiable in spectral data must be used in order to infer the petrologic history of asteroids from surveys of their actual population. As discussed below, olivine composition (e.g. Fa#) can provide key constraints in exploring the origin and significance of olivine dominated asteroids.

Sunshine, J. M.; Bus, S. J.; Burbine, T. H.; McCoy, T. J.

2005-01-01

261

Minor elements in lunar olivine as a petrologic indicator  

NASA Technical Reports Server (NTRS)

Accurate electron microprobe analyses (approximately 50 ppm) were made for Al, Ca, Ti, Cr, Mn, and Ni in Mg-rich olivines which may derive from early lunar crust or deeper environments. Low-Ca contents consistently occur only in olivines from dunitic and troctolitic breccia: spinel troctolite and other rock types have high-Ca olivines suggesting derivation by near-surface processes. Rock 15445 has olivine with distinctly low CaO (approximately 0.01 wt.%). Chromium ranges to higher values (max.0.2 oxide wt.%) than for terrestrial harzburgites and lherzolites but is similar to the range in terrestrial komatiites. Divalent chromium may be indicated over trivalent Cr because olivines lack sufficient other elements for charge balance of the latter. NiO values in lunar specimens range from 0.00 to 0.07 wt.% and a weak anticorrelation with Cr2O3 suggests an oxidation state effect. Al2O3 values are mostly below 0.04-wt.% and show no obvious correlation with fragment type. TiO2 values lie below 0.13-wt.% and seem to correlate best with crystallization rate and plagioclase content of the host rock. High values of Al2O3 and TiO2 reported by other workers have not been confirmed, and are probably wrong.

Steele, I. M.; Smith, J. V.

1975-01-01

262

Weathering of olivine under CO2 atmosphere: A martian perspective  

NASA Astrophysics Data System (ADS)

Recent analyses from the Curiosity rover at Yellowknife Bay (Gale crater, Mars) show sedimentary rocks deposited in a lacustrine environment and containing smectite clays thought to derive from the alteration of olivine. However, little is known about the weathering processes of olivine under early martian conditions, and about the stability of smectite clays in particular. Here, we present a 3-month experiment investigating the weathering of forsteritic olivine powders (Fo90) under a dense CO2 atmosphere, and under present-day terrestrial conditions for comparison. The experiment also evaluates the potential effects of hydrogen peroxide (H2O2), as a representation of the highly oxidizing compounds produced by photochemical reactions throughout martian history. The weathered samples were characterized by means of near-infrared spectroscopy (NIR), X-ray diffraction (XRD), transmission electron microscopy with energy dispersive X-ray spectrometry (TEM-EDX), Mössbauer spectroscopy and thermogravimetry. The results show that a Mg-rich smectite phase formed from the weathering of olivine under CO2 conditions, although in lower abundance than under terrestrial conditions. The main secondary phase formed under CO2 turns out to be a silica-rich phase (possibly acting as a “passivating” layer) with a non-diagnostic near-infrared spectral signature. The use of H2O2 highlights the critical importance of both the redox conditions and Fe content of the initial olivine on the nature of the secondary phases.

Dehouck, E.; Gaudin, A.; Mangold, N.; Lajaunie, L.; Dauzères, A.; Grauby, O.; Le Menn, E.

2014-06-01

263

Grain boundary diffusion in olivine (Invited)  

NASA Astrophysics Data System (ADS)

Olivine is the main constituent of Earth's upper mantle. The individual mineral grains are separated by grain boundaries that have very distinct properties compared to those of single crystals and strongly affect large-scale physical and chemical properties of rocks, e.g. viscosity, electrical conductivity and diffusivity. Knowledge on the grain boundary physical and chemical properties, their population and distribution in polycrystalline materials [1] is a prerequisite to understand and model bulk (rock) properties, including their role as pathways for element transport [2] and the potential of grain boundaries as storage sites for incompatible elements [3]. Studies on selected and well characterized single grain boundaries are needed for a detailed understanding of the influence of varying grain boundaries. For instance, the dependence of diffusion on the grain boundary structure (defined by the lattice misfit) and width in silicates is unknown [2, 4], but limited experimental studies in material sciences indicate major effects of grain boundary orientation on diffusion rates. We characterized the effect of grain boundary orientation and temperature on element diffusion in forsterite grain boundaries by transmission electron microscopy (TEM).The site specific TEM-foils were cut using the focused ion beam technique (FIB). To study diffusion we prepared amorphous thin-films of Ni2SiO4 composition perpendicular to the grain boundary using pulsed laser deposition. Annealing (800-1450°C) leads to crystallization of the thin-film and Ni-Mg inter-diffuse into the crystal volume and along the grain boundary. The inter-diffusion profiles were measured using energy dispersive x-ray spectrometry in the TEM, standardized using the Cliff-Lorimer equation and EMPA measurements. We obtain volume diffusion coefficients that are comparable to Ni-Mg inter-diffusion rates in forsterite determined in previous studies at comparable temperatures, with similar activation energies. Grain boundary diffusion perpendicular to the dislocation lines of the small angle grain boundaries proved to be about an order of magnitude faster than volume diffusion, whereas diffusion in high angle grain boundaries is several orders of magnitude faster. We will discuss the variation of element diffusion rates with grain boundary orientation and the temperature- and/or time-induced transition from one diffusion regime to the next regime. This is done using time series experiments and two-dimensional grain boundary diffusion simulations. Finally, we will debate the differences between our data and other data sets that result from different experimental setups, conditions and analyses.

Marquardt, K.; Dohmen, R.

2013-12-01

264

Exotic Olivine in Antarctic Angrites LEW 87051 and Asuka 881371  

NASA Astrophysics Data System (ADS)

Angrites are basaltic meteorites with very early formation ages [e.g., 1] suggesting magrnatic activity on their parent body shortly after accretion. To constrain the nature of this magmatism, it is necessary to determine the composition of the melts parental to the angrite meteorites so that these melts can be compared with known phase relationships. Of the four known angrites, Angra dos Reis is highly differentiated and has had a complex history [e.g.,2]. LEW 86010 is probably a low-temperature partial melt containing minor accumulated plagioclase [3]. LEW 87051 (LEW 87) contains porphyritic olivine in a fine-grained groundmass, and the olivine crystals have variously been interpreted as phenocrysts [e.g., 4], xenocrysts [e.g., 5], and compound crystals in which exotic xenocryst cores have been overgrown by olivine that crystallized from the melt [e.g 6]. Asuka 881371 (Asuka 88) contains large olivine crystals in a medium-grained groundmass [7 and these large olivines are unambiguously xenocrysts that are not directly related to the melt in which they now reside [9], and may shed light on the olivines in LEW 87. Several lines of evidence point towards the exotic nature of the large olivines in Asuka 88. Despite being internally homogeneous, these crystals show large variations in composition from one crystal to another. Such variations are shown for Ca and Mg/Mg+Fe in Fig. 1, but are also observed for Cr, Al, and Y. Moreover, the concentrations of these elements in the large olivines are different from the concentrations in the cores of the groundmass olivines that were obviously the first minerals to crystallize from the Asuka 88 melt (Fig 1). Thus the large olivines could not have been in equilibrium with one another nor with the host melt. Furthermore, along healed fractures the the large olivines have been altered towards the groundmass olivine composition either through physical invasion of melt or by enhanced surface diffusion along the fractures. However, despite the clear exotic relationship to the Asuka 88 melt, the O isotopic composition of one olivine xenocryst falls within the angrite group [9], so the xenocrysts are probably not completely exotic to the angrite parent body. By analogy with Asuka 88, we infer that the Mg-rich cores of some porphyritic olivines in LEW 87 are xenocrysts (Fig. 1), but the main portions of these crystals surrounding the cores (labeled LEW 87 phenos in Fig. 1) grew from the LEW 87 melt. Agreement in minor elements between the main portions of LEW 87 olivines and synthetic olivines from LEW 87 experiments supports this interpretation (Fig. 1). We plan to use elemental mapping to locate more cores in LEW 87, to look for core-to-core variation and to measure additional profiles to test for diffusive equilibration between xenocrysts and the outer part of the olivine or groundmass. Using the compositions of first olivines to crystallize from the parent melts of both meteorites and K(sub)(DFe/Mg) of 0.29 from LEW 87 crystallization experiments, we calculate that the bulk compositions reported for Asuka 88 by [9] and LEW 87 by [12] have about 11% and 20% excess olivine (exotic or accumulated) of Fo(sub)83 and Fo(sub)81 respectively. References: [1] Nyquist L. et al. (1994) Meteoritics, 29, 872-885. [2] Mittlefehldt D. and Lindstrom M. (1990) GCA, 54, 3209-3218. [3] McKay G. et al. (1988) LPS XIX, 762-763. [4] McKay G. et al. (1990) LPS XXI, 771-772. [5] Prinz et al. (1990) LPS XXI, 979. [6] Mikouchi T. et al. (1995) LPS XXVI, 973-974. [7] Yanai K. (1994) Proc. NIPR Symp. Antarc. Meteorites, 7, 30-41. [8] McKay G. et al. (1995) Antarc. Meteorites, XX, 155-158. [9] Warren P. et al. (1995) Antarc. Meteorites, XX, 261-264. [10] Warren P. and Kallemeyn G. (1990) LPS XXI, 1295-1296.

McKay, G.; Crozaz, G.; Mikouchi, T.; Miyamoto, M.

1995-09-01

265

An olivine-free mantle source of Hawaiian shield basalts.  

PubMed

More than 50 per cent of the Earth's upper mantle consists of olivine and it is generally thought that mantle-derived melts are generated in equilibrium with this mineral. Here, however, we show that the unusually high nickel and silicon contents of most parental Hawaiian magmas are inconsistent with a deep olivine-bearing source, because this mineral together with pyroxene buffers both nickel and silicon at lower levels. This can be resolved if the olivine of the mantle peridotite is consumed by reaction with melts derived from recycled oceanic crust, to form a secondary pyroxenitic source. Our modelling shows that more than half of Hawaiian magmas formed during the past 1 Myr came from this source. In addition, we estimate that the proportion of recycled (oceanic) crust varies from 30 per cent near the plume centre to insignificant levels at the plume edge. These results are also consistent with volcano volumes, magma volume flux and seismological observations. PMID:15800614

Sobolev, Alexander V; Hofmann, Albrecht W; Sobolev, Stephan V; Nikogosian, Igor K

2005-03-31

266

Thermal Emission Spectroscopy of 1 Ceres: Evidence for Olivine  

NASA Technical Reports Server (NTRS)

Thermal emission spectra of the largest asteroid, 1 Ceres, obtained from the Kuiper Airborne Observatory display features that may provide information about its surface mineralogy. The emissivity, obtained by dividing the spectra by a standard thermal model, is compared with emissivity spectra of olivines and phyllosilicates deduced via Kirchoff's law from reflectivity measurements. The spectra provide a fairly good match to fine grained olivines (0 to 5 micrometer size range). The smoothness of the spectrum beyond 18 micrometers is an indication of particles smaller than 50 micrometers. While the abrupt rise in emissivity near 8 micrometers matches many silicates, the distinct emissivity minimum centered near 12.8 micrometers is consistant with iron-poor olivines, but not with phyllosilicates. It suggests the presence of opaques and does not exclude a mixture with organics and fine-grained phyllosilicates.

Witteborn, Fred. C.; Roush, Ted L.; Cohen, Martin

1999-01-01

267

Dislocation recovery in fine-grained polycrystalline olivine  

NASA Astrophysics Data System (ADS)

The rate of static dislocation recovery in Fo90 olivine has been studied under conditions of high temperature and controlled atmosphere in compressively deformed polycrystals hot-pressed from synthetic (sol-gel) and natural (San Carlos) precursor powders. The sol-gel olivine, containing a small fraction of orthopyroxene, was deformed to a final strain of 19% with a maximum differential stress of 266 MPa whereas the San Carlos specimen was deformed to 15% strain and 260 MPa differential stress. Small samples cut from these deformed materials were annealed under high-temperature, controlled atmosphere conditions, for different durations to allow partial recovery of the dislocation sub-structures. Oxidative-decoration of the microstructural features, followed by backscattered electron imaging at 5 kV and image analysis, was used to determine dislocation density. The variation of dislocation density ? with time t at absolute temperature T was fitted to a second-order rate equation, in integral form, 1/?( t) - 1/?(0) = kt with k = k 0 exp(- E a/RT). The activation energy E a of the recovery process is 240 ± 43 and 355 ± 81 kJ mol-1 for sol-gel and San Carlos olivine polycrystals, respectively. The measured rates are one to two orders of magnitude lower than those reported in previous studies on natural single crystal olivine. The difference may be explained by several factors such as high dislocation densities measurable from large areas at high magnification for the SEM and the technique used to estimate dislocation densities. Comparison between fine-grained sol-gel olivine and the coarser-grained San Carlos olivine aggregate did not indicate that grain boundaries play an important role in dislocation recovery, but the absence of grain boundaries might also have contributed to the high dislocation recovery rates previously measured for single crystals.

Farla, R. J. M.; Kokkonen, H.; Fitz Gerald, J. D.; Barnhoorn, A.; Faul, U. H.; Jackson, I.

2011-05-01

268

Electrical Conductivity of Hydrous Single Crystal San Carlos Olivine  

NASA Astrophysics Data System (ADS)

The electrical conductivity of anhydrous San Carlos olivine is too low to explain the observed electrical conductivity of Earth's upper mantle. Although the solubility of hydrogen in olivine is relatively low at mantle P and T conditions, it has been estimated that even at concentrations of less than 1000 ppm, electrical conductivity is enhanced by as much as a factor of one hundred, based on a conduction mechanism involving hydrogen diffusion (Karato, Nature 347, 272-273, 1990). In this study we have measured the electrical conductivity of hydrated San Carlos olivine single crystals, oriented along (100), (010) and (001). SCO single crystals were first oriented, machined into 2 mm diameter cylinders, and then sandwiched between layers of a talc+brucite mix in sealed Pt capsules for hydration runs at pressures up to 8 GPa and 1200°C in a multianvil apparatus. Recovered samples were then cut into wafers ranging from 0.2 to 0.6 mm in thickness for subsequent complex impedance measurements to determine electrical conductivity, also carried out at high pressure. For the electrical measurements, temperatures were limited to about 700°C in order to minimize loss of water from the sample. FTIR spectroscopy was used to determine water content of samples both before and after the electrical measurements. Preliminary results indicate that at concentrations of a few hundred ppm water, conductivities are several orders of magnitude higher than for dry olivine. Activation energies decrease with increasing water content, indicating that extrapolation of conductivities to higher temperatures leads to a smaller overall effect. However, based on these results, at upper mantle conditions, the presence of minor amounts of hydrogen in olivine is sufficient to bridge the gap between the conductivity of dry olivine and that of the mantle.

Poe, B.; Romano, C.; Nestola, F.; Rubie, D.

2005-12-01

269

The composition of mineral inclusions in the olivines of pallasites  

NASA Astrophysics Data System (ADS)

An examination of a number of pallasite meteorites revealed the composition of primary and secondary solid inclusions as well as the composition of gaseous inclusions in the olivines. It is shown that the gaseous inclusions in the olivine of the Bragin meteorite consist of nitrogen and rare gases as well as carbon dioxide and hydrogen; the absence of oxygen is evidence of reduction during crystallization. Both one-phase and two-phase inclusions were disclosed; the two-phase inclusions consist of both solid and gaseous components. Phosphate minerals reveal traces of the spontaneous fission of uranium, plutonium-244, and possibly an unknown superheavy element.

Kolomenskii, V. D.; Dolivo-Dobrovolskaia, G. I.; Perelygin, V. P.

270

Amoeboid olivine aggregates from CH carbonaceous chondrites  

NASA Astrophysics Data System (ADS)

Amoeboid olivine aggregates (AOAs) in CH carbonaceous chondrites are texturally and mineralogically similar to those in other carbonaceous chondrite groups. They show no evidence for alteration and thermal metamorphism in an asteroidal setting and consist of nearly pure forsterite (Fa<3; in wt%, CaO = 0.1-0.8, Cr2O3 = 0.04-0.48; MnO < 0.5), anorthite, Al-diopside (in wt%, Al2O3 = 0.7-8.1; TiO2 < 1), Fe,Ni-metal, spinel, and, occasionally, low-Ca pyroxene (Fs1Wo2-3), and calcium-aluminum-rich inclusions (CAIs). The CAIs inside AOAs are composed of hibonite, grossite, melilite (Åk13-44), spinel, perovskite, Al,Ti-diopside (in wt%, Al2O3 up to 19.6; TiO2 up to 13.9), and anorthite. The CH AOAs, including CAIs within AOAs, have isotopically uniform 16O-rich compositions (average ?17O = -23.4 ± 2.3‰, 2SD) and on a three-isotope oxygen diagram plot along ?slope-1 line. The only exception is a low-Ca pyroxene-bearing AOA 1-103 that shows a range of ?17O values, from -24‰ to -13‰. Melilite, grossite, and hibonite in four CAIs within AOAs show no evidence for radiogenic 26Mg excess (?26Mg). In contrast, anorthite in five out of six AOAs measured has ?26Mg corresponding to the inferred initial 26Al/27Al ratio of (4.3 ± 0.7) × 10-5, (4.2 ± 0.6) × 10-5, (4.0 ± 0.3) × 10-5, (1.7 ± 0.2) × 10-5, and (3.0 ± 2.6) × 10-6. Anorthite in another AOA shows no resolvable ?26Mg excess; an upper limit on the initial 26Al/27Al ratio is 5 × 10-6. We infer that CH AOAs formed by gas-solid condensation and aggregation of the solar nebula condensates (forsterite and Fe,Ni-metal) mixed with the previously formed CAIs. Subsequently they experienced thermal annealing and possibly melting to a small degree in a 16O-rich gaseous reservoir during a brief epoch of CAI formation. The low-Ca pyroxene-bearing AOA 1-103 may have experienced incomplete melting and isotope exchange in an 16O-poor gaseous reservoir. The lack of resolvable ?26Mg excess in melilite, grossite, and hibonite in CAIs within AOAs reflects heterogeneous distribution of 26Al in the solar nebula during this epoch. The observed variations of the inferred initial 26Al/27Al ratios in anorthite of the mineralogically pristine and uniformly 16O-rich CH AOAs could have recorded (i) admixing of 26Al in the protoplanetary disk during the earliest stages of its evolution and/or (ii) closed-system Mg-isotope exchange between anorthite and Mg-rich minerals (spinel, forsterite, and Al-diopside) during subsequent prolonged (days-to-weeks) thermal annealing at high temperature (?1100 °C) and slow cooling rates (?0.01 K h-1) that has not affected their O-isotope systematics. The proposed thermal annealing may have occurred in an impact-generated plume invoked for the origin of non-porphyritic magnesian chondrules and Fe,Ni-metal grains in CH and CB carbonaceous chondrites about 5 Myr after formation of CV CAIs.

Krot, Alexander N.; Park, Changkun; Nagashima, Kazuhide

2014-08-01

271

Results from a Mössbauer and VNIR Study of Dust Generated from Olivine Basalt: Application to Mars  

NASA Astrophysics Data System (ADS)

It is shown that VNIR spectroscopy can greatly underestimate the ratio of olivine to pyroxene and olivine may be more abundant on Mars than hitherto believed. The possibilities of using electrodes to collect samples on Mars are discussed.

Mølholt, T. E.; Gunnlaugsson, H. P.; Merrison, J. P.; Morris, R. V.; Nørnberg, P.; Madsen, M. B.

2009-03-01

272

Olivine and Carbonate Globules in ALH84001: A Terrestrial Analog, and Implications for Water on MARS.  

National Technical Information Service (NTIS)

Carbonate globules in ALH84001 are associated with small olivine grains - an unexpected finding because the olivines equilibrated at high T while the carbonate is chemically zoned and unequilibrated. A possible explanation comes from a terrestrial analog ...

A. H. Treiman

2005-01-01

273

Trace Element Distribution Between Olivine and Kirschsteinite in Angra Dos Reis  

NASA Astrophysics Data System (ADS)

Kirschsteinite occurs interstitially to olivine grains in olivine aggregates in the Angra dos Reis angrite. Trace element abundances in these two phases in Angra dos Reis are similar to trace element abundances in these phases in LEW86010.

Fittipaldo, M. M.; Jones, R. H.; Shearer, C. K.

2003-03-01

274

Chemical Zoning and Diffusion of Ca, Al, Mn, and Cr in Olivine of Springwater Pallasite.  

National Technical Information Service (NTIS)

The pallasites, consisting mainly of Fe-Ni metal and olivine, are thought to represent the interior of a planetary body which slowly cooled from high temperature. Although the olivines are nearly homogeneous, ion microprobe studies revealed variations of ...

Y. Zhou I. M. Steele

1993-01-01

275

Evidence for equilibrium conditions during the partitioning of nickel between olivine and komatiite liquids.  

USGS Publications Warehouse

Olivine-liquid partition coefficients for Ni(DNi), calculated from Ni vs MgO abundance variations in komatiite series basalts, compare favourably with experimentally determined values, if Ni variations in olivine-controlled basalts can be modelled with an equation that assumes equilibrium between the entire olivine crystal and its coexisting liquid.-J.A.Z.

Budahn, J. R.

1986-01-01

276

Micro FT/IR Analysis of Brown Olivines in Martian Meteorites  

NASA Astrophysics Data System (ADS)

We analyzed the spectra of martian meteorites with brown olivine by micro FT/IR, and the olivine from shock-recovery experiment under 40 GPa by ATR. The results indicate that the midinfrared reflectance of olivine correspond to their darkness.

Koizumi, E.; Mikouchi, T.; Monkawa, A.; Kurihara, T.; Miyamoto, M.

2010-03-01

277

A Study of Olivine Alteration to Iddingsite Using Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

A crucial task of Mars surface science is to determine past environmental conditions, especially aqueous environments and their nature. Identification of mineral alteration by water is one way to do this. Recent work interprets TES spectra as indicating altered basalt on Mars. Olivine, a primary basaltic mineral, is easily altered by aqueous solutions. Alteration assemblages of olivine may be specific to deuteric, hydrothermal, surface water, or metamorphic environments. Raman spectra are produced by molecular vibrations and provide direct means for studying and identifying alteration products. Here, we present a combined study of changes in the chemical composition and Raman spectra of an olivine as it alters to iddingsite. Iddingsite is found in some SNC meteorites and is presumably present on Mars. The term 'iddingsite' has been used as a catch-all term to describe reddish alteration products of olivine, although some authors ascribe a narrower definition: an angstrom-scale intergrowth of goethite and smectite (presumably saponite) formed in an oxidizing and fluid-rich environment. Alteration conserves Fe (albeit oxidized) but requires addition of Al and H2O and removal of Mg and Si. The smectite that forms may be removed by continued alteration. Dehydration of the goethite forms hematite. Our purpose is to study the mineral assemblage, determine the structural and chemical variability of the components with respect to the degree of alteration, and to find spectral indicators of alteration that will be useful during in-situ analyses on Mars.

Kuebler, K. E.; Wang, Alian; Haskin, L. A.; Jolliff, B. L.

2003-01-01

278

Mn, Co and Ni diffusion profiles in pallasite olivine  

NASA Astrophysics Data System (ADS)

Using LA-ICP-MS, we have measured diffusion profiles for Co, and in some cases also been successful in obtaining Mn and Ni profiles, in olivine from the Brahin and Brenham pallasite meteorites and used them to constrain their relative cooling rates.

McKibbin, S. J.; O'Neill, H. S. C.; Mallmann, G.

2011-10-01

279

Far-infrared continuum absorption of olivine at low temperatures  

NASA Astrophysics Data System (ADS)

The far-infrared continuum opacity of cold dust is an important quantity for the study of debris disks in planetary systems and of protoplanetary disks. Olivine is considered the most abundant crystalline dust species in such environments. We present spectroscopic absorption measurements on olivine plates of the order of a millimeter thickness at wavelengths between 60 and 400 ?m for temperatures down to 10 K. Our data reveal a strong temperature dependence of the continuum absorption coefficient, i.e. more than an order of magnitude decrease at 100 ?m for 10 K compared to room temperature. The absolute values are generally much lower than those measured with olivine powders embedded into polyethylene pellets, even if the difference between plate and powder samples is taken into account by theoretical models. In contrast to this, the room temperature data are in relatively good agreement with simulations using optical constants determined from reflection measurements. At low temperatures, the absorption coefficient of olivine was measurable with sufficient accuracy only up to 90 ?m for 10 K and up to 110 ?m for 100 K. These data reveal a drastic change in the spectral slope (from ? ˜ 2.0 to ? > 5.0) for the continuum underlying the 69-?m band, which is not predicted by the low-temperature optical constants determined for forsterite.

Mutschke, H.; Zeidler, S.; Chihara, H.

2013-10-01

280

Implications for the evolution of chondrules from Agglomeratic olivine chondrules  

NASA Technical Reports Server (NTRS)

There is considerable evidence that chondrules formed by the melting of solid materials and, by default, the early solar nebula is the preferred location for chondrule formation. Agglomeratic olivine (AO) chondrules supply perhaps the most intriguing, direct evidence for chondrule formation from agglomeration of solids. We review the characteristics of AO chondrules and discuss their implications for understanding chondrule precursors and chondrule evolution.

Weisberg, M. K.; Prinz, M.

1994-01-01

281

The role of recrystallization in the preferred orientation of olivine  

Microsoft Academic Search

The effects of recrystallization on the preferred orientation in olivine have been studied. The recrystallization mechanisms studied include grain growth, the deformation-induced grain boundary migration (DIGBM) and subgrain rotation (SGR). Grain boundary migration is involved in the first two, but not in SGR. Significant preferred orientation was found only in the latter two where dislocations are involved. The combined microstructural

Shun-Ichiro Karato

1988-01-01

282

Deformation of olivine in torsion under hydrous conditions  

NASA Astrophysics Data System (ADS)

We performed torsional deformation experiments on pre-hydrated fine-grained olivine aggregates using an innovative experimental assembly to investigate water weakening in mantle rocks at high shear strains. San Carlos olivine powder was cold-pressed and then hot-pressed under hydrous conditions, producing aggregates with average grain sizes of 7 or 15 ?m. Deformation experiments were performed in a high-resolution gas-medium apparatus equipped with a torsional actuator, under a confining pressure of 300 MPa, a temperature of 1200 °C, and constant shear strain rates ranging from 8 × 10-5 to 1.4 × 10-4 s-1. Maximum shear stresses range from 150 to 195 MPa. These values are 30% lower relative to those determined in previous torsion experiments on dry, fined-grained dunites under similar conditions. Textures and microstructures of the starting and deformed specimens were characterized by scanning and transmission electron microscopy. All deformed aggregates exhibit a shape-preferred orientation marking a foliation and lineation, as well as a reduction in mean grain size from 15 ?m down to 3-4 ?m due to dynamic recrystallization. Olivine crystallographic fabrics developed rapidly (? < 0.1), but their strength, characterized by the J-index, is low compared to naturally deformed peridotites or to polycrystalline olivine deformed at similar finite shear strains under dry conditions. The crystallographic fabrics are consistent with deformation by a dislocation accommodated creep mechanism with activation of multiple {0 k l}[1 0 0] systems, among which the (0 1 0)[1 0 0] slip system is dominant, and minor participation of the (0 1 0)[0 0 1] slip system. Transmission electron microscopy confirmed the occurrence of dislocations with [1 0 0] and [0 0 1] Burgers vectors in most grains. Analysis of unpolarized infrared spectra indicates that hydrogen concentration in the olivine lattice is below the saturation level of 18 ppm wt H2O, which is similar to those typically observed in spinel-bearing peridotite xenoliths, and also provide evidence for water-rich inter-granular material trapped in pores and grain boundaries. Seismic properties computed from the CPO observations correspond to those most commonly observed in naturally deformed mantle peridotites with fast P-wave propagation and S-wave polarization subparallel to the shear direction. These torsion experiments on fine-grained olivine polycrystals under hydrous conditions indicate that water weakening under lithospheric conditions is linked to various defects with hydrogen in the olivine structure, as well as with water-derived species in grain boundaries or pores.

Demouchy, Sylvie; Tommasi, Andréa; Barou, Fabrice; Mainprice, David; Cordier, Patrick

2012-08-01

283

Olivine in kimberlites: metasomatism of the deep lithospheric mantle  

NASA Astrophysics Data System (ADS)

Most kimberlites contain abundant mantle microxenoliths (nodules) and xenocrysts, mainly composed of olivine. We present here a geochemical and microstructural study of nodules from well-preserved type-I kimberlites from Kangamiut region in Greenland, the sequel of a preliminary study of Arndt et al. (2010). A striking feature of these and many other kimberlites is the wide range of olivine composition (Fo83 to Fo94) from nodule to nodule in a single kimberlite sample, contrasting with the olivine homogeneity within a single nodule (variation of less than 0.5 mol. %). We defined three chemical zones within normally zoned nodules based on Fo and Ni variations. Xenocrystic cores have high and constant Fo and Ni contents. Outer rims crystallized from the kimberlitic magma have constant Fo content (Fo88) coupled with significant decrease in Ni content (from 2500 to 500 ppm). Transition zones between cores and rims, along grain boundaries and along fluid inclusion trails have variable Fo content (Fo93 to Fo88) but roughly constant Ni content (from 3000 to 25000 ppm) and their composition mimics that defined by the nodules. Microstructural study of transition zones associated with curvilinear grain boundaries suggests these zones are produced during fluid-assisted plastic deformation. We propose that the transition zones formed during reaction of mantle peridotite with CO2-rich fluid, a process that removes the pyroxene and garnet components. The compositional variations of the transition zones monitor at the fine scale the processes that produce the chemical variability of olivine from nodule to nodule. We propose that the range of olivine composition records the position of sample relative to fluid-rich zones, grain boundaries for transition zones and larger conduits for broader scale variations registered in the nodules. This conclusion implies that metasomatic processes that produced the range of olivine composition and removed pyroxene and garnet from the initial peridotite occurred within the lithospheric mantle and not within the kimberlite magma during it ascent toward the surface. Arndt, N. T.; Guitreau, M.; Boullier, A. M.; Le Roex, A.; Tommasi, A.; Cordier, P. & Sobolev, A. V. (2010): Olivine, and the origin of kimberlite. Journal of Petrology, 51, 573-602.

Cordier, Carole; Sauzeat, Lucie; Arndt, Nicholas; Boullier, Anne-Marie

2014-05-01

284

Activities of olivine slip systems in the upper mantle  

NASA Astrophysics Data System (ADS)

We investigated the effect of pressure (P) on olivine [1 0 0](0 0 1) and [0 0 1](1 0 0) dislocation slip systems by carrying out deformation experiments in the Deformation-DIA apparatus (D-DIA) on single crystals of Mg2SiO4 forsterite (Fo100) and San Carlos (SC) olivine (Fo89), at P ranging from 5.7 to 9.7 GPa, temperature T = 1473 and 1673 K, differential stress ? in the range 140-1500 MPa, and in water-poor conditions. Specimens were deformed in axisymmetry compression along the so-called [1 0 1]c crystallographic direction, which promotes the dual slip of [1 0 0] dislocations in (0 0 1) plane and [0 0 1] dislocations in (1 0 0) plane. Constant ? and specimen strain rates (??) were monitored in situ by synchrotron X-ray diffraction and radiography, respectively. Comparison of the obtained high-P rheological data with room-P data, previously reported by Darot and Gueguen (1981) for Fo100 and Bai et al. (1991) for SC olivine, allowed quantifying the activation volume V* in classical creep power laws. We obtain V* = 9.1 ± 1.6 cm3/mol for Fo100. For SC olivine, we obtain V* = 10.7 ± 5.0 cm3/mol taking into account the oxygen-fugacity uncertainty during the high-P runs. These results, combined with previous reports, provide complete sets of parameters for quantifying the activities of olivine dislocation slip systems. Extrapolation of the rheological laws obtained for SC olivine crystals to conditions representative of natural deformations show that [1 0 0](0 1 0) slip largely dominates deformation in the shallow upper mantle. At depths greater than ˜65 km along a 20-Ma oceanic geotherm or ˜155 km along a continental geotherm, the dual activity of [1 0 0](0 0 1) and [0 0 1](1 0 0) slips becomes comparable to that of [1 0 0](0 1 0) slip. At depths greater than ˜240 km, [0 0 1](0 1 0) slip becomes dominant over all other investigated slip systems. Such changes in olivine dislocation-slips relative activity provide a straightforward explanation for the seismic anisotropy contrast and attenuation with depth observed in the Earth's upper mantle.

Raterron, Paul; Girard, Jennifer; Chen, Jiuhua

2012-06-01

285

The effect of mineral paragenesis on Al diffusion in olivine  

NASA Astrophysics Data System (ADS)

Al is the most abundant trivalent impurity of olivine and is particularly important because its concentration in olivine is temperature dependant, and it therefore has potential as a geothermometer (Wan, et al. 2008). Furthermore recent studies show that the incorporation of water into the olivine lattice is affected by the presents of trivalent cations such as Al3+ (Berry, et al. 2007; Hauri, et al. 2006). The Al distribution in olivines from volcanic rocks is often zoned and mantle olivines may also show an inhomogeneous distribution of Al, whereas the majority of other trace elements homogenized by diffusion (Mallmann, et al. 2009; McKibbin, et al.). However, there are no quantitative experimental data for Al diffusion in olivine, probably because the combination of low concentration rate and low diffusion rate make measurement difficult. We investigated the effect of silica activity on the diffusion rate of Al in forsterite at varying temperatures using solid-state buffer assemblages. Our study aimed to quantify the effect of major cation activities on the diffusion and concentration of Al in forsterite and also provide insights into the mechanism of Al substitution into the olivine lattice. The activities of SiO2, MgO and Al2O3 were buffered in each experiment by four different mineral associations: forsterite + periclase + spinel (fo+per+sp); forsterite + spinel + sapphirine (fo+sp+spr); forsterite + sapphirine + cordierite (fo+spr+cor); forsterite + cordierite + enstatite (fo+cor+en). Iron oxide in proportion of FeO/(FeO+MgO) = 0.1 was added to mixtures for San Carlos olivine experiments. Diffusion experiments were performed at the one-atmosphere vertical tube furnaces modified to control the fO2 by CO-CO2 gas mixing or in a box furnace in air for 10 - 28 days at temperatures from 1100 to 1500oC and logfO2 -0.7 and -5.7. The experiment with the San Carlos olivine was performed at 1300oC and at logfO2 = -5.7. In order to obtain equilibrium concentrations of the point defects we performed some experiments with pre-annealing. Diffusion profiles were measured by LA-ICP-MS in a traverse mode. The Al content of forsterite decreases with temperature dependence, increasing the potential of Al in olivine as a geothermometer. We obtain the activation energy of 379 kJ/mol for the high aSiO2 experiments, which is close within error of the value of 364 kJ/mol for the low aSiO2 experiments implying a common diffusion mechanism. The pre-exponential factor, however, increases by 5 orders of magnitude from low aSiO2 (fo+per+sp buffer) to high aSiO2 (fo+cor+en buffer). The much higher diffusivity at high aSiO2 indicates that Al diffusion occurs through octahedral cation site vacancies.

Zhukova, Irina; O'Neill, Hugh; Capbell, Ian

2014-05-01

286

Geoengineering potential of artificially enhanced silicate weathering of olivine  

PubMed Central

Geoengineering is a proposed action to manipulate Earth’s climate in order to counteract global warming from anthropogenic greenhouse gas emissions. We investigate the potential of a specific geoengineering technique, carbon sequestration by artificially enhanced silicate weathering via the dissolution of olivine. This approach would not only operate against rising temperatures but would also oppose ocean acidification, because it influences the global climate via the carbon cycle. If important details of the marine chemistry are taken into consideration, a new mass ratio of CO2 sequestration per olivine dissolution of about 1 is achieved, 20% smaller than previously assumed. We calculate that this approach has the potential to sequestrate up to 1 Pg of C per year directly, if olivine is distributed as fine powder over land areas of the humid tropics, but this rate is limited by the saturation concentration of silicic acid. In our calculations for the Amazon and Congo river catchments, a maximum annual dissolution of 1.8 and 0.4 Pg of olivine seems possible, corresponding to the sequestration of 0.5 and 0.1 Pg of C per year, but these upper limit sequestration rates come at the environmental cost of pH values in the rivers rising to 8.2. Open water dissolution of fine-grained olivine and an enhancement of the biological pump by the rising riverine input of silicic acid might increase our estimate of the carbon sequestration, but additional research is needed here. We finally calculate with a carbon cycle model the consequences of sequestration rates of 1–5 Pg of C per year for the 21st century by this technique.

Kohler, Peter; Hartmann, Jens; Wolf-Gladrow, Dieter A.

2010-01-01

287

Geoengineering potential of artificially enhanced silicate weathering of olivine.  

PubMed

Geoengineering is a proposed action to manipulate Earth's climate in order to counteract global warming from anthropogenic greenhouse gas emissions. We investigate the potential of a specific geoengineering technique, carbon sequestration by artificially enhanced silicate weathering via the dissolution of olivine. This approach would not only operate against rising temperatures but would also oppose ocean acidification, because it influences the global climate via the carbon cycle. If important details of the marine chemistry are taken into consideration, a new mass ratio of CO(2) sequestration per olivine dissolution of about 1 is achieved, 20% smaller than previously assumed. We calculate that this approach has the potential to sequestrate up to 1 Pg of C per year directly, if olivine is distributed as fine powder over land areas of the humid tropics, but this rate is limited by the saturation concentration of silicic acid. In our calculations for the Amazon and Congo river catchments, a maximum annual dissolution of 1.8 and 0.4 Pg of olivine seems possible, corresponding to the sequestration of 0.5 and 0.1 Pg of C per year, but these upper limit sequestration rates come at the environmental cost of pH values in the rivers rising to 8.2. Open water dissolution of fine-grained olivine and an enhancement of the biological pump by the rising riverine input of silicic acid might increase our estimate of the carbon sequestration, but additional research is needed here. We finally calculate with a carbon cycle model the consequences of sequestration rates of 1-5 Pg of C per year for the 21st century by this technique. PMID:21059941

Köhler, Peter; Hartmann, Jens; Wolf-Gladrow, Dieter A

2010-11-23

288

The geoengineering potential of artificially enhanced silicate weathering of olivine  

NASA Astrophysics Data System (ADS)

Geoengineering is a proposed action to manipulate Earth's climate in order to counteract global warming from anthropogenic greenhouse gas emissions. We investigate in more detail the potential of a specific geoengineering technique, the carbon sequestration by artificially enhanced silicate weathering via the dissolution of olivine. This approach would not only operate against rising temperatures but would also oppose ocean acidification, because it influences the global climate via the carbon cycle. We here show the consequences of this technique for the chemistry of the surface ocean at rates necessary for geoengineering. We calculate that olivine dissolution has the potential to sequestrate up to one Pg C yr-1 directly, if olivine is distributed as fine powder over land areas of the humid tropics. The carbon sequestration potential is limited by the saturation concentration of silicic acid. In our calculations for the Amazon and Congo river catchments a maximum annual dissolution of 1.8 and 0.4 Pg of olivine seems possible, corresponding to the sequestration of 0.5 and 0.1 Pg C yr-1. Open water dissolution of fine grained olivine and an enhancement of the biological pump by the rising riverine input of silicic acid might increase our estimate of the carbon sequestration, but additional research is needed here. We finally calculate with a carbon cycle model the consequences of sequestration rates of 1 to 5 Pg C yr-1 for the 21st century by this technique. At maximum this technique would reduce global warming by 1 K and counteract ocean acidification by a rise in surface ocean pH by 0.1 in the year 2100.

Köhler, Peter; Hartmann, Jens; Wolf-Gladrow, Dieter A.

2010-05-01

289

Achondrite ALHA77005 - Alteration of chromite and olivine  

NASA Technical Reports Server (NTRS)

The olivine crystals of the 77005 achondrite are brown except for colorless shock lamellae, mottled patches, and grains adjacent to pools of impact melt. Sporadic dark alteration patches in brown olivine and Cr-rich spinel gave the following average electron-microprobe analyses: (olivine) P2O5 0.9, SiO2 57.9, TiO2 0, Al2O3 0.7, Cr2O3 0.4, V2O3 0, Fe2O3 (assumed oxidation state) 17.0, MgO 1.6, CaO 0.2, Na2O 0, K2O 1.8, SO3 (assumed oxidation state) 9.2, Cl 0.1, sum 89.8 wt pct; (spinel) P2O5 3.5, SiO2 2.1, TiO2 2.2, Al2O3 2.1, Cr2O3 13.4, V2O3 0.8, Fe2O3 40.7, MgO 0.9, CaO 0.1, Na2O 0, K2O 2.0, SO3 11.1, Cl 0.1, sum 79.0 wt pct. Ion-microprobe analyses revealed H in both. Rare orange patches in brown olivine from another area gave SiO2 33-35, FeO 30-28, MgO 28-32, sum 93 wt pct. Thermal metamorphism under dry oxidizing conditions is discussed as a possible alternative to shock-induced oxidation for generation of the brown olivine (McSween and Stoeffler, 1980). Because alteration patches transgress shock lamellae, and because sulfatic alteration occurs in fusion crusts of Antarctic meteorites (Gibson et al., 1983), alteration of the 77005 achondrite at the Antarctic surface is preferred to a complex series of processes needed for preterrestrial alteration.

Smith, J. V.; Steele, I. M.

1984-01-01

290

Kamacite and olivine in ordinary chondrites: Intergroup and intragroup relationships  

SciTech Connect

The three principal groups of ordinary chondrites (OCs), H (high total Fe), L (low total Fe), and LL (low total Fe, low metallic Fe), constitute {approximately}80% of all meteorites observed to fall. In going from H to L to LL chondrites, the abundances of siderophile elements decrease and the degree of oxidation increases. The proportion of oxidized Fe (i.e., FeO in silicates) increases at the expense of metallic Fe. Because Fe is more readily oxidized than Ni or Co, bulk metal becomes increasingly rich in Ni and Co (e.g., Prior, 1916). Equilibrated LL chondrites are thus characterized by high FeO/(FeO + MgO) ratios in olivine and low-Ca pyroxene, high taenite/kamacite ratios, and the occurrence of Co-rich kamacite. The present study reports high-precision electron microprobe analyses of olivine and kamacite in a large suite of OCs. The purpose of the study was sixfold: (1) rigorously define the compositional ranges of these phases for each OC group, (2) identify anomalous OCs whose olivine and/or kamacite compositions lie outside the established ranges, and hence may not belong to the three main OC groups, (3) characterize the phases in the chondritic clasts of the Netschaevo iron meteorite and determine how closely related Netschaevo is to OCs, (4) determine if there are intragroup variations of olivine and kamacite compositions with petrologic type, (5) identify those OCs as fragmental breccias that contain some olivine and/or kamacite grains with aberrant compositions, and (6) search for new metallic Fe-Ni phases with extreme compositions. An expected by-product of this investigation was that a few meteorites that previously had not been well-characterized would be reclassified.

Rubin, A.E. (Univ. of California, Los Angeles (USA))

1990-05-01

291

Achondrite ALHA77005 - Alteration of chromite and olivine  

NASA Astrophysics Data System (ADS)

The olivine crystals of the 77005 achondrite are brown except for colorless shock lamellae, mottled patches, and grains adjacent to pools of impact melt. Sporadic dark alteration patches in brown olivine and Cr-rich spinel gave the following average electron-microprobe analyses: (olivine) P2O5 0.9, SiO2 57.9, TiO2 0, Al2O3 0.7, Cr2O3 0.4, V2O3 0, Fe2O3 (assumed oxidation state) 17.0, MgO 1.6, CaO 0.2, Na2O 0, K2O 1.8, SO3 (assumed oxidation state) 9.2, Cl 0.1, sum 89.8 wt pct; (spinel) P2O5 3.5, SiO2 2.1, TiO2 2.2, Al2O3 2.1, Cr2O3 13.4, V2O3 0.8, Fe2O3 40.7, MgO 0.9, CaO 0.1, Na2O 0, K2O 2.0, SO3 11.1, Cl 0.1, sum 79.0 wt pct. Ion-microprobe analyses revealed H in both. Rare orange patches in brown olivine from another area gave SiO2 33-35, FeO 30-28, MgO 28-32, sum 93 wt pct. Thermal metamorphism under dry oxidizing conditions is discussed as a possible alternative to shock-induced oxidation for generation of the brown olivine (McSween and Stoeffler, 1980). Because alteration patches transgress shock lamellae, and because sulfatic alteration occurs in fusion crusts of Antarctic meteorites (Gibson et al., 1983), alteration of the 77005 achondrite at the Antarctic surface is preferred to a complex series of processes needed for preterrestrial alteration.

Smith, J. V.; Steele, I. M.

1984-09-01

292

Reaction-induced weakening of plagioclase olivine composites  

NASA Astrophysics Data System (ADS)

The localisation of strain into natural ductile shear zones is often associated with the occurrence of metamorphic reactions. In order to study the effects of solid-solid mineral reactions on plastic deformation of rocks, we have investigated the shear deformation of plagioclase-olivine composites during the reaction plagioclase + olivine ? orthopyroxene + clinopyroxene + spinel (± garnet). Microstructures of plagioclase-olivine composites were studied after shear deformation experiments in a Griggs apparatus. Experiments were performed on anorthite-forsterite (An-Fo) and labradorite-forsterite (Lab-Fo) composites at 900 °C, confining pressures between 1000-1600 MPa and with constant shear strain rates of ˜5 × 10 -5 s -1. In absence of reaction, Lab-Fo composites are stronger than pure olivine and labradorite end-members that deform with a high temperature plasticity mechanism. Lab-Fo composites strain-harden due to the inhibition of extensive recrystallisation by interphase boundaries. In An-Fo composites, the reaction induces strain weakening by a switch from dislocation creep to grain size sensitive deformation mechanisms through the development of fine-grained (size < 0.5 ?m) polyphase reaction products. Interconnecting layers of reaction products accommodate most of the applied strain by grain size sensitive creep. Recovery processes are pronounced during syndeformational reaction: original anorthite and olivine dynamically recrystallise by subgrain rotation and bulging recrystallisation. Presumably, the dynamic recrystallisation is caused by reduced stress conditions and partitioning of strain and strain rates between the new reaction products and the relict An-Fo grains. The results of our experiments are in good agreement with natural observations of shear localisation in the lower crust and upper mantle, and imply that anhydrous mineral reactions can be important causes for localisation of deformation.

de Ronde, A. A.; Stünitz, H.; Tullis, J.; Heilbronner, R.

2005-11-01

293

Characterization by EBSD of dislocations and disclinations in olivine: implications for the rheology of olivine-rich aggregates  

NASA Astrophysics Data System (ADS)

The rheology of olivine-rich rocks remains poorly understood. Only intracrystalline deformation mechanisms involving dislocations are quite well known. In orthorhombic olivine only two slip directions, [100] and [001] can be activated. Most characterizations performed so far involve transmission electron microscopy studies at high magnifications or, at a larger scale, optical or scanning electron microscopy on decorated samples. In the latter case, no detailed characterization of the defects could be done. Orientation maps obtained from high-resolution electron backscattered diffraction allow recovering components of the lattice curvature tensor which in turn allow determination of components of the dislocation density tensor. The geometrically necessary dislocation content can thus be imaged. Recently Beausir & Fressengeas (2013) have shown that with this technique, components of the disclination density tensor could also be determined. Several examples have been provided in metallic alloys. In this study we show that olivine aggregates (both experimentally and naturally deformed) contain pervasive evidence of disclinations dipoles at grain boundaries. The implications on the plastic behavior of olivine rocks are discussed based on a numerical model of the response to an applied shear stress of a grain boundary made of disclinations. Beausir, B. & Fressengeas, C., Disclination densities from EBSD orientation mapping. International Journal of Solids and Structures 50 (1), 137-146 (2013).

Cordier, P.; Demouchy, S. A.; Beausir, B.; Taupin, V.; Fressengeas, C.

2013-12-01

294

Olivine and Carbonate Globules in ALH84001: A Terrestrial Analog, and Implications for Water on Mars  

NASA Technical Reports Server (NTRS)

Carbonate globules in ALH84001 are associated with small olivine grains an unexpected finding because the olivines equilibrated at high T while the carbonate is chemically zoned and unequilibrated. A possible explanation comes from a terrestrial analog on Spitsbergen (Norway), where some carbonate globules grew in cavities left by aqueous dissolution of olivine. For ALH84001, the same process may have acted, with larger olivines dissolved out and smaller ones shielded inside orthopyroxene. Carbonate would have been deposited in holes where the olivine had been. Later shocks crushed remaining void space, and mobilized feldspathic glass around the carbonates.

Treiman, A. H.

2005-01-01

295

Experimental constraints on magnetic stability of chondrules and the paleomagnetic significance of dusty olivines  

NASA Astrophysics Data System (ADS)

Dynamic crystallization experiments are conducted under a magnetic field to determine both magnetic and mineralogical properties of chondrules. The experiment reproduced synthetic dusty olivine samples that were formed by a high temperature reduction of an initially fayalitic olivine. Backscattered-electron microscopy observations confirmed that synthetic dusty olivine contains abundant fine, submicron-sized Ni-poor Fe inclusions in the cores of MgO-rich olivine grains, similar to that in natural chondrules. Alternating field demagnetization experiments of dusty olivine samples indicate mean destructive fields of up to 80 mT, suggesting the submicron-sized Fe inclusions are a carrier of stable remanence. In natural chondrules, fine Fe inclusions in the dusty olivine may have been armored against chemical alteration by surrounding host olivine crystals. Since the fine Fe inclusions were probably heated above the Curie temperature during the last chondrule forming events, the fine Fe inclusions in dusty olivine can acquire thermal remanent magnetization during the chondrule formation event. Theoretical time-temperature relation of such fine-grained Fe (kamacite) grains suggested that a paleomagnetic data observed above 490 °C in thermal demagnetization experiments of dusty olivines is reliable despite the low-grade metamorphism of unequilibrated ordinary chondrites (e.g., LL3.0). Therefore, the presence of fine Fe inclusions in dusty olivine in unequilibrated ordinary chondrites constrains that such dusty olivine in chondrules is a good candidate as an un-altered and stable magnetic recorder of the early solar magnetic field.

Uehara, Minoru; Nakamura, Norihiro

2006-10-01

296

The solubility of olivine in basaltic liquids - An ionic model  

NASA Technical Reports Server (NTRS)

A model is presented which enables the temperature at which olivine is in equilibrium with any alkali-depleted basaltic compound to be calculated to within + or - 30 C. It is noted that the error increases substantially when applied to terrestrial basalts which contain several weight percent alkalis. In addition the model predicts and quantifies the reduced activity of SiO4(4-) monomers due to increasing SiO2 concentrations in the melt. It is shown that the coordination of alumina in melts which precipitate olivine only appears to be dominantly octahedral, while titanium acts as a polmerizing agent by interconnecting previously isolated SiO4(4-) monomers. It is concluded that the model is sufficiently sensitive to show that there are small repulsive forces between Mg(2+) and calcium ions which are in association with normative diopside in the melt.

Herzberg, C. T.

1979-01-01

297

Olivine flotation and crystallization of a global magma ocean  

NASA Astrophysics Data System (ADS)

According to the so-called olivine flotation hypothesis, basic silicate liquids become denser than coexisting ultramafic crystalline peridotites at high pressures through their higher compressibility. Therefore, the olivine, crystallizing from a global magma ocean, settles to a neutrally buoyant zone at about 250 km depth dividing the molten outer part of the Earth into two oceans separated by a dunite septum. The thermal evolution of such a divided global magma ocean is investigated using simple stability estimates and cooling time calculations. It appears that the cooling times and styles of convection (overturn, penetrative, layered) depend strongly on the surface temperature. Overturn convection leads to a compleate destruction of the dunite septum while in the case of penetrative convection the septum is only partly passed through. Thus, separate chemical evolution of the two mantle regions operates only at high surface temperatures near the solidus of mantle silicates of about 1500 K and cooling times of about 105 years.

Franck, Siegfried

1992-11-01

298

Olivine and pyroxene diversity in the crust of Mars.  

PubMed

Data from the Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) on the Mars Express spacecraft identify the distinct mafic, rock-forming minerals olivine, low-calcium pyroxene (LCP), and high-calcium pyroxene (HCP) on the surface of Mars. Olivine- and HCP-rich regions are found in deposits that span the age range of geologic units. However, LCP-rich regions are found only in the ancient Noachian-aged units, which suggests that melts for these deposits were derived from a mantle depleted in aluminum and calcium. Extended dark regions in the northern plains exhibit no evidence of strong mafic absorptions or absorptions due to hydrated materials. PMID:15718427

Mustard, J F; Poulet, F; Gendrin, A; Bibring, J-P; Langevin, Y; Gondet, B; Mangold, N; Bellucci, G; Altieri, F

2005-03-11

299

Visualizing frozen point defect tracks in Fe-containing olivines  

NASA Astrophysics Data System (ADS)

Using a combination of first-principles calculations and Monte Carlo simulations, we show that Fe-containing silicates such as olivines naturally offer a way for visualizing tracks left by diffusing vacancies. Fe in its 2+ and 3+ valency states prefers two distinct cation sites in the olivine structure. Vacancies formed at the cationic M sites, cause neighboring Fe ions in their normally occurring Fe2+ state to change valency to Fe3+, compensating for the charge imbalance and reducing energy costs, consequently altering the local site preference of Fe. Once the vacancy diffuses away, Fe atoms remain stuck in their metastable location producing a microscopic record of the vacancy's trajectory. Our results may be verified using high-resolution transmission electron microscopy, combined with electron energy-loss spectroscopy.

Chatterjee, S.; Saha-Dasgupta, T.; Sengupta, S.

2012-04-01

300

First-principles studies of native defects in olivine phosphates  

NASA Astrophysics Data System (ADS)

Olivine phosphates LiMPO4 (M=Mn, Fe, Co, Ni) are promising candidates for rechargeable Li-ion battery electrodes because of their energy storage capacity and electrochemical and thermal stability. It is known that native defects have strong effects on the performance of olivine phosphates. Yet, the formation and migration of these defects are not fully understood, and we expect that once such understanding has been established, one can envisage a solution for improving the materials' performance. In this talk, we present our first-principles density-functional theory studies of native point defects and defect complexes in LiMPO4, and discuss the implications of these defects on the performance of the materials. Our results also provide guidelines for obtaining different native defects in experiments.

Hoang, Khang; Johannes, Michelle

2011-03-01

301

Waveform effects of a metastable olivine tongue in subducting slabs  

NASA Technical Reports Server (NTRS)

Velocity models of subducting slabs with a kinetically-depressed olivine to beta- and gamma-spinel transition are constructed, and the effect that such structures would have on teleseismic P waveforms are examined using a full-wave finite-difference method. These 2D calculations yielded waveforms at a range of distances in the downdip direction. The slab models included a wedge-shaped, low-velocity metastable olivine tongue (MOTO) to a depth of 670 km, as well as a plausible thermal anomaly; one model further included a 10-km-thick fast layer on the surface of the slab. The principal effect of MOTO is to produce grazing reflections at wide angles off the phase boundary, generating a secondary arrival 0 to 4 seconds after the initial arrival depending on the take-off angle. The amplitude and timing of this feature vary with the lateral location of the seismic source within the slab cross-section.

Vidale, John E.; Williams, Quentin; Houston, Heidi

1991-01-01

302

Iron-Titanium Oxides and Olivine from 10020 and 10071  

Microsoft Academic Search

A new mineral (approximately Fe0.5Mg0.5Ti2O5) related to the pseudobrookite series has been discovered in section 10071,28. Electron-probe analyses for this mineral, a coexisting ilmenite, and a chromian ulvospinel-ilmenite assemblage in section 10020,40 indicate crystallization under highly reducing conditions. Analytical and optical absorption studies of the olivine in 10020 show it to contain unusually high Cr (1400 parts per million) probably

S. E. Haggerty; F. R. Boyd; P. M. Bell; L. W. Finger; W. B. Bryan

1970-01-01

303

An olivine-microchondrule-bearing clast in the Krymka meteorite  

SciTech Connect

A small (150 x 200-micron-size) clast consisting of 20 vol pct olivine microchondrules (with barred and granular textures) and 80 vol pct recrystallized silicate matrix material occurs in Krymka (LL3.1). This is the fourth microchondrule-bearing clast to be described. The chondrules are zoned in FeO with concentrations increasing toward the surface. The clast most closely resembles a previously described radial-pyroxene-microchondrule-bearing clast in Piancaldoli (LL3.4). 8 refs.

Rubin, A.E. (California Univ., Los Angeles (USA))

1989-09-01

304

Chemical frost weathering of olivine: Experimental study and implications  

NASA Technical Reports Server (NTRS)

New experimental results are reported on the frost weathering of olivine. After first weathering, a decrease in Fe sup 2(+)M(2) absorption bands were noted. This decrease is related to the protonation of O(+) in the mineral. It is contented that this reaction may result in the regolith storage of 100 to 1000 m of H(sub 2) over the history of Mars.

Harris, S. L.; Huguenin, R. L.

1987-01-01

305

Chromium valences in ureilite olivine and implications for ureilite petrogenesis  

NASA Astrophysics Data System (ADS)

Ureilites are a group of ultramafic achondrites commonly thought to be residues of partial melting on a carbon-rich asteroid. They show a large variation in FeO content (olivine Fo values ranging from ˜74 to 95) that cannot be due to igneous fractionation and suggests instead variation in oxidation state. The presence of chromite in only a few of the most ferroan (Fo 75-76) samples appears to support such a model. MicroXANES analyses were used in this study to determine the valence states of Cr (previously unknown) in olivine cores of 11 main group ureilites. The goal of this work was to use a method that is independent of Fo to determine the oxidation conditions under which ureilites formed, in order to evaluate whether the ureilite FeO-variation is correlated with oxidation state, and whether it is nebular or planetary in origin. Two of the analyzed samples, LEW 88774 (Fo 74.2) and NWA 766 (Fo 76.7) contain primary chromite; two others, LAP 03587 (Fo 74.4) and CMS 04048 (Fo 76.2) contain sub-micrometer-sized exsolutions of chromite + Ca-rich pyroxene in olivine; and one, EET 96328 (Fo 85.2) contains an unusual chromite grain of uncertain origin. No chromite has been observed in the remaining six samples (Fo 77.4-92.3).

Goodrich, C. A.; Sutton, S. R.; Wirick, S.; Jercinovic, M. J.

2013-12-01

306

Origin of plagioclase-olivine inclusions in carbonaceous chondrites  

SciTech Connect

Plagioclase-Olivine Inclusions (POIs) are an abundant group of chondrule-like objects with igneous textures found in carbonaceous chondrites. POIs consist of plagioclase, olivine, pyroxene, and spinel, and cover a wide range of compositions between Type C Ca-Al-rich Inclusions (CAIs) and ferromagnesian chondrules. POIs are distinguished from CAIs by the absence of melilite, lack of refractory siderophile-rich opaque assemblages, more sodic plagioclase, and abundance of olivine and aluminousenstatite. Rare accessory minerals including armalcolite, zirconolite, rutile, and sapphirine are found in several POIs. The petrographic and chemical properties of POIs indicate that they are not condensates or evaporative residues but formed by melting or partial melting of pre-existing solids. Seven of fourteen POIs contain isotopically fractionated Mg, and despite their textures these POIs are not isotopically homogeneous. A comparison of the essential characteristics of POIs and CAIs suggests that the major processes leading to formation of POIs - including condensation, dust/gas fractionation, aggregation of chemically and isotopically disparate materials, and partial melting - are common to most CAIs and chondrules. We present a scenario for the formulation of these objects and conclude that the homogeneity of the final assemblage - CAI, POI, or chondrule - is primarily a reflection of the thermal history rather than the nature of precursor materials.

Sheng, Y.J.; Hutcheon, I.D.; Wasserburg, G.J. (California Inst. of Tech., Pasadena (USA))

1991-02-01

307

Morphology and electrical properties of conductive carbon coatings for cathode materials  

Microsoft Academic Search

Many interesting cathode materials, such as LiFePO4, LiMnPO4, LiFeBO3 or the recently discovered Li2FeSiO4 and Li2MnSiO4, exhibit extremely low electronic conductivity (<10?9Scm?1). A very efficient way for improving the electronic transport in such materials is supposed to be the preparation of carbon coatings around individual active particles. Despite the increasing number of reports on preparation of various carbon coatings, neither

Joze Moskon; Robert Dominko; Romana Cerc-Korosec; Miran Gaberscek; Janez Jamnik

2007-01-01

308

Electrode materials for aqueous rechargeable lithium batteries  

Microsoft Academic Search

In this review, we describe briefly the historical development of aqueous rechargeable lithium batteries, the advantages and\\u000a challenges associated with the use of aqueous electrolytes in lithium rechargeable battery with an emphasis on the electrochemical\\u000a performance of various electrode materials. The following materials have been studied as cathode materials: LiMn2O4, MnO2, LiNiO2, LiCoO2, LiMnPO4, LiFePO4, and anatase TiO2. Addition of

H. Manjunatha; G. S. Suresh; T. V. Venkatesha

2011-01-01

309

Dislocations in olivine: insights from numerical modeling (Invited)  

NASA Astrophysics Data System (ADS)

Olivine (Mg,Fe)2SiO4 is the main constituent of the Earth’s upper mantle (down to 410 km deep). The rheology of, and convection in, the upper mantle are therefore controlled by the deformation mechanisms of this mineral. Numerous experimental studies have been undertaken leading to a good description of the deformation mechanisms and rheological properties of this mineral at low pressure < 1 GPa. Based on this knowledge, crystallographic preferred orientations in olivine are commonly used to infer fossil mantle flow patterns from seismic anisotropy measurements. However, recent studies have shown that [001] glide is enhanced over [100] glide when pressure increases or when trace amounts of water are dissolved in the crystals(1). These observations have a lot of implications on our understanding of the rheology of the upper mantle and call for a more detailed description of dislocation cores and dynamics. The Peierls-Nabarro (PN) model including ?-surface energies has been used to model dislocation cores in olivine. However, the standard approach, which is restricted to the description of planar cores, which cannot be universally applied in the case of olivine. The occurrence in olivine of long straight screw [001] dislocations raise the question of the origin of lattice friction. A recent study based on full atomistic calculations (using the THB1 potential) has shown that [001] screw dislocations exhibit 3D core spreading(2). This issue must be addressed to understand the [100] to [001] glide crossover and its potential sensitivity to pressure. In this study, a novel method coupling Peierls-Nabarro and element-free Galerkin methods (called PNG) is presented. This technique expands the possibilities of previously reported calculations, in particular in permitting the modeling of 3D dislocation cores. We show that, [100] dislocations may exhibit non-collinear dissociation in the (010) plane. The PNG model confirms the occurrence of 3D core spreading of [001] screw dislocations. The lattice friction is not very sensitive to confining pressure between 0 and 10 GPa. However, [001] dislocations exhibit a complex sensitivity to the applied shear stress tensor with a significant deviation from the Schmid law under pressure. (1) Jung, Mo & Green (2009) Nature Geoscience 2, 73. (2) Carrez, Walker, Metsue & Cordier (2008) Phil. Mag. 88(16), 2477.

Cordier, P.; Metsue, A.; Carrez, P.; Denoual, C.; Mainprice, D.

2009-12-01

310

Fe/Mn in olivine of carbonaceous meteorites  

NASA Technical Reports Server (NTRS)

Olivines in primitive meteorites show a range of Fe/Mn both within one grain and among grains suggesting that they have recorded changing conditions during or after growth. Because olivine should be an early forming phase, Fe/Mn is used here to infer these earliest conditions. Initial Fe/Mn in cores of isolated, euhedral forsterite in both C2 and C3 meteorites ranges from 25 to 35 but differs at grain edge. Murchison (C2) forsterites show Fe/Mn approaching 1.0 at the grain edge while Ornans Fe/Mn is near 60 at grain edge. These values are lower than the matrix Fe/Mn for both meteorites and the distinct difference in zoning profile indicates different processes operating during and after grain growth. The Fe/Mn of bulk samples from a particular source such as the Moon is nearly constant. Individual samples show variation suggesting that there is some fractionation of Mn from Fe. Minerals have their individual ranges of Fe/Mn which has been used to recognize different types of olivine within one meteorite. Extreme values of Fe/Mn below 1.0 occur in forsterite from some IDP's, UOC matrix, and C1 meteorites. There are apparently no detailed studies of Fe/Mn variation within single olivine grains. Forsterite grains in C2 and C3 carbonaceous chondrites show complex zoning, and the nearly pure forsterites (Fo greater than approximately 99.5) have high levels of some minor elements including Ti, Al, V, and Sc. There is disagreement on the original source of these grains and both chondrule and vapor growth have been proposed. In addition, there is clear evidence that diffusion has affected the outer margins but in some cases the whole grain. Within the cores, the FeO range is limited, and if growing under constant conditions, the Fe/Mn should be near constant as there is little fractionation of Mn from Fe by forsterite. Additionally, there are apparently no co-crystallizing phases as evidenced by a lack of common inclusions in the forsterites. These observations are now followed by analyses of isolated olivine grains in C2 and C3 meteorites.

Steele, Ian M.

1993-01-01

311

A New Spinel-Olivine Oxybarometer: Near-Liquidus Partitioning of V between Olivine-Melt, Spinel-Melt, and Spinel-Olivine in Martian Basalt Composition Y980459 as a Function of Oxygen Fugacity  

NASA Technical Reports Server (NTRS)

Our research on valence state partitioning began in 2005 with a review of Cr, Fe, Ti, and V partitioning among crystallographic sites in olivine, pyroxene, and spinel [1]. That paper was followed by several on QUE94201 melt composition and specifically on Cr, V, and Eu partitioning between pyroxene and melt [2-5]. This paper represents the continuation of our examination of the partitioning of multivalent V between olivine, spinel, and melt in martian olivine-phyric basalts of Y980459 composition [6, 7]. Here we introduce a new, potentially powerful oxybarometer, V partitioning between spinel and olivine, which can be used when no melt is preserved in the meteorite. The bulk composition of QUE94201 was ideal for our study of martian pyroxene-phyric basalts and specifically the partitioning between pyroxene-melt for Cr, V, and Eu. Likewise, bulk composition Y980459 is ideal for the study of martian olivine-phyric basalts and specifically for olivine-melt, spinel-melt, and spinel-olivine partitioning of V as a function of oxygen fugacity.

Papike, J. J.; Le, L.; Burger, P. V.; Shearer, C. K.; Bell, A. S.; Jones, J.

2013-01-01

312

Nepheline and sodalite in a barred olivine chondrule from the Allende meteorite  

NASA Astrophysics Data System (ADS)

The discovery of nepheline and sodalite in association with glass in a barred olivine chondrule from the Allende C3V meteorite is reported, and the possible origin of the minerals is discussed. Scanning electron microscope/energy dispersive analysis indicates that the major minerals of the chondrule are olivine, bronzite and chromite, with olivine bars separated by glass of nearly pure plagioclase composition. The olivine is observed to have a composition richer in Fe than that predicted from olivine-liquid equilibria, indicating, along with the presence of plagioclase glass and small amounts of subcalcic diopside, the nonequilibrium crystallization of the barred olivine chondrule. The textural features of the chondrule are consistent with a liquid origin for nepheline and sodalite from the chondrule-forming liquid under nonequilibrium conditions.

Lumpkin, G. R.

1980-06-01

313

Olivine reactivity with CO 2 and H 2O on a microscale: Implications for carbon sequestration  

Microsoft Academic Search

The silicate mineral olivine, (Mg,Fe)2SiO4, reacts exothermally with CO2 and forms secondary minerals, including carbonates. Therefore olivine reaction is a promising process for carbon sequestration, to convert carbon dioxide from the atmosphere to mineral form. The purpose of this study was: 1) to explore the composition, structure and reactivity of olivine surfaces during exposure to air and to water at

J. Olsson; N. Bovet; E. Makovicky; K. Bechgaard; Z. Balogh; S. L. S. Stipp

314

[Study on the FTIR spectra of OH in olivines from mengyin kimberlite].  

PubMed

The results of FTIR spectra study of OH in olivines from Mengyin kimberlite show that there are more than 60 OH absorption peaks in the range of 3800-3000 cm(-1). We identified four major spectral features in the OH absorption bands of kimberlitic olivines. One is with nuOH in the range of 3800-3700 cm(-1), which is caused by the vapour of the room circumstance, and can not be regarded as intrinsic or non-intrinsic nuOH of the olivines. Another one is with nuOH in the range of 3710-3620 cm(-1), which belongs to three "water"-bearing minerals including serpentine, talc and Mg-bearing amphiboles, which is the non-intrinsic nuOH of the olivines. There is the possibility that H in hydrous minerals mainly entered into olivines during post-emplacement processes of the kimberlite magma. The third one is with nuOH in the range of 3620-3425 cm(-1), which originated from H occupying the Si-defect in the olivine structure, forming humite-like defects, and/or the defects that H occupies (Mg,Fe)-depletion, which is certainly attributed to the intrinsic nuOH of the olivines. In this case, H possibly entered into olivines following its immersion in the high temperature and rich fluid kimberlite magma in the mantle circumstance. The last one is with nuOH in the range of 3425-3000 cm(-1). In this area, nuOH is assigned to fluid inclusions of the olivines, and is the non-intrinsic nuOH of olivines. Fluid inclusions can enter into the olivines either during post-emplacement processes of the kimberlite magma or during the periods that olivines were formed in the mantle. PMID:24369634

Ai, Qun; Yang, Zhi-jun; Zeng, Xiang-qing; Zheng, Yun-long; Hu, Piao-ye

2013-09-01

315

Origins of compositional heterogeneity in olivine-hosted melt inclusions from the Baffin Island picrites  

Microsoft Academic Search

The Baffin Island picrites are highly magnesian (?22 wt% MgO) olivine tholeiites, erupted through felsic continental crust. Plots of most major and minor element oxides against MgO for the lavas define very tight trends consistent with modification of melts parental to the erupted suite by olivine fractionation or accumulation. However, melt inclusions trapped in primitive olivine phenocrysts in these lavas have

Gregory M. Yaxley; Vadim S. Kamenetsky; Maya Kamenetsky; Marc D. Norman; Don Francis

2004-01-01

316

Inherited Pb isotopic records in olivine antecryst-hosted melt inclusions from Hawaiian lavas  

NASA Astrophysics Data System (ADS)

Dislocation textures of olivine grains and Pb isotopic compositions (207Pb/206Pb and 208Pb/206Pb) of olivine-hosted melt inclusions in basaltic lavas from three Hawaiian volcanoes (Kilauea, Mauna Loa, and Koolau) were examined. More than 70% of the blocky olivine grains in the studied samples have a regular-shaped dislocation texture with their dislocation densities exceeding 106 cm-2, and can be considered as deformed olivine. The size distribution of blocky olivine grains shows that more than 99% of blocky olivines coarser than 1.2 mm are identified as deformed olivine. These deformed olivine grains are identified as antecrysts, which originally crystallized from previous stages of magmatism in the same shield, followed by plastic deformation prior to entrainment in the erupted host magmas. This study revealed that entrainment of mantle-derived crystallization products by younger batches of magma is an important part of the evolution of magnesium-rich Hawaiian magma. Lead isotopic compositions of melt inclusions hosted in the olivine antecrysts provide information of the evolutionary history of Hawaiian volcanoes which could not have been accessed if only whole rock analyses were carried out. Antecryst-hosted melt inclusions in Kilauea and Koolau lavas demonstrate that the source components in the melting region changed during shield formation. In particular, evidence of interaction of plume-derived melts and upper mantle was observed in the earliest stage of Koolau magmatism.

Sakyi, Patrick Asamoah; Tanaka, Ryoji; Kobayashi, Katsura; Nakamura, Eizo

2012-10-01

317

Origin of graphitic carbon and pentlandite in matrix olivines in the Allende meteorite.  

PubMed

Matrix olivines in the Allende carbonaceous chondrite are believed to have formed by condensation processes in the primitive solar nebula. However, transmission electron microscope observations of numerous matrix olivines show that they contain abundant, previously unrecognized, nanometer-sized inclusions of pentlandite and poorly graphitized carbon. Neither of these phases would have been stable at the high-temperature conditions required to condense iron-rich olivine in the solar nebula. The presence of these inclusions is consistent with formation of the olivines by parent body processes that involved overgrowth of fine-grained organic materials and sulfides in the precursor matrix materials. PMID:10464092

Brearley, A J

1999-08-27

318

Can hypervelocity impacts onto olivine generate serpentine and thus methane?  

NASA Astrophysics Data System (ADS)

A possible source for martian methane is the serpentinisation of olivine. It could be possible for this conversion to occur as a result of impacts. A series of experiments are being carried using the light gas gun at the University of Kent to determine the likelihood of this occurring, and to quantify the percentage of serpentine produced relative to the projectile's volume. To date the results show no detectable evidence of serpentinisation at impact velocities of 5 km s-1 are lower indicating: i) higher speeds may be required to produce serpentine, ii) the degree of serpentinisation is very small or, iii) this process does not occur as a result of impacts.

Ramkissoon, N. K.; Price, M. C.; Burchell, M. J.; Cole, M. J.

2013-09-01

319

Effect of Water on High Pressure Olivine Slip Systems Activity  

NASA Astrophysics Data System (ADS)

Seismologic studies of the Earth's shallow (Z<220 km) upper mantle have observed seismic anisotropy parallel to the direction of plate movement and have related this observation to alignment of olivine [100] due to shearing related to convection. These observations have been reinforced by field-based and experimental investigations which observe evidence that [100] slip is dominant at low pressures and water contents. However, direct evidence of the dominant slip system in the deep upper mantle (Z>220 km) is limited to a few studies of xenoliths which have LPOs consistent with [001] slip. Experimental studies of dry single crystals and polycrystals indicate that [001] slip becomes dominant at pressures > 8 GPa. However, water contents in the mantle are significant (~1000 H/106 Si) and we do not know how the slip systems of olivine are affected by higher water contents at high pressures. In order to investigate the effect of pressure on slip systems activities in olivine deformed in wet conditions, deformation experiments were carried out on single crystals, at pressure ranging from 4 to 8 GPa and temperature between 1373 and 1473 K in the Deformation-DIA apparatus (D-DIA) of the X17B2 beamline of the NSLS (NY, USA). Specimen were deformed in uniaxial compression along [110]c, [011]c and [101]c crystallographic directions, promoting the activation of, respectively, [100](010), [001](010) slip systems, and simultaneously [100](001) and [001](100) slip systems. Talc sleeves about the annulus of the single crystals were used as source of water during deformation. In addition, run products investigation using a micro-focused IR beam at the U2 beamline enables accurate mapping of the water content across the deformed single crystals using FTIR spectroscopy, while specimen deformation microstructures were investigated by TEM. We observe a slip-system transition in wet specimen occurring at lower pressure than that observed by Raterron et al. (2007) in dry specimens. For each investigated crystal orientation, the pressure effect on the slip-system activity has been quantified and the hydrolytic weakening has also been estimated. Our results confirm that pressure induces the dominant slip system transition in olivine, and show that water lowers the transition pressure by weakening [001] slip more significant than [100] slip.

Girard, J.; Chen, J.; Raterron, P. C.; Holyoke, C. W.

2012-12-01

320

Type-C olivine LPOs in garnet peridotites in North Qaidam UHP collision belt, NW China  

NASA Astrophysics Data System (ADS)

Water is known to change the lattice-preferred orientation (LPO) of olivine, which significantly affects seismic anisotropy in the Earth's upper mantle. Research into the LPO of olivine in the deep interior of the Earth has been limited due to inadequate specimens. We report both the water-induced LPOs of olivine and the presence of large quantities of water inside olivine, enstatite, and garnet in garnet peridotites from the North Qaidam ultrahigh-pressure (UHP) collision belt in NW China. We show that the [001] axis of olivine is aligned subparallel to the lineation and that the [100] axis is strongly aligned subnormal to the foliation. This alignment is a known feature of type-C LPO of olivine formed experimentally under water-rich conditions (?700 ppm H/Si) at high pressure and temperature. Enstatite possessed an LPO with the [001] axis aligned parallel to the lineation and the [100] axis aligned normal to the foliation. FTIR analysis of this specimen revealed that olivine contained concentrations of water up to 1130 × 50 ppm H/Si in clean areas, whereas olivine, enstatite, and garnet contained considerably more water, i.e., 2600 × 100 ppm H/Si, 5000 × 100 ppm H/Si, and 21000 × 200 ppm H/Si, respectively, when exsolved inclusions were visible. Confocal micro-Raman spectroscopy of these exsolved inclusions revealed that they were composed of hornblende and amphiboles. Straight dislocations were also commonly observed in olivine and are characteristic of olivine that had been experimentally deformed under hydrous conditions. These observations suggest that the type-C LPO of olivine in the North Qaidam UHP belt formed under water-rich conditions.

Jung, H.; Lee, J.; Ko, B.; Jung, S.; Park, M.; Cao, Y.; Song, S.

2013-12-01

321

Complex Zoning of Olivine from Udachnaya-East Kimberlite (yakutia, Russia): Evidence for Kimberlite Evolution  

NASA Astrophysics Data System (ADS)

Olivine (Fo 86-94) is a dominant mineral in kimberlites, and it is completely altered in absolute majority of them. Udachnaya kimberlites contain a huge block of absolutely unaltered ultrafresh olivine with a lack of serpentine even in thin sections. Two main olivine populations which are represented by rounded or anhedral olivine-I macrocrysts and euhedral olivine-II phenocrysts are clearly distinguished in any kimberlites including Udachnaya (e.g. Kamenetsky et al., 2008, J. Petrol. 49: 823-839; Brett et al., 2009, Lithos, 112S: 201-212). Both of these olivine types are represented by variable proportions of resorbed homogeneous core and complex zoned rim parts. Several grains of zoned olivines with both normal and reverse zoning, and wide variations of "core" and "rim" ratios were selected for this study. The zones of "rims" area vary in width with number of zones sometimes exceeding five or six. Concentrations of Ni, Mn, Co, Ca, Cr, Al, Ti, P, and Zn were measured by EPMA using an innovative method, which has been developed based on earlier publication (Sobolev et al., Science, 2007, 316: 412-417). The method made possible to obtain external precision down to 10 ppm (2SD) and detection limit down to 2 ppm. In addition, high resolution compositional maps of olivine zoning for all mentioned elements are produced. Five and more different zones of variable width and shape were detected for "rims" area of several zoned olivine grains. It has been confirmed both by element maps and EPMA study. As a result several growth events of olivine rims with variations of all measured trace element contents are documented which may provide new approach in understanding the origin of kimberlitic olivine, dynamics of its growth and evolution of kimberlite itself.

Sobolev, N. V.; Sobolev, A. V.; Tomilenko, A. A.; Kovyazin, S.; Kuzmin, D.

2012-12-01

322

Morphology and surface features of olivine in kimberlite: implications for ascent processes  

NASA Astrophysics Data System (ADS)

Most kimberlite rocks contain large proportions of ellipsoidal-shaped xenocrystic olivine grains that are derived mainly from disaggregation of peridotite. Here, we describe the shapes, sizes and surfaces of olivine grains recovered from kimberlite lavas erupted from the Quaternary Igwisi Hills volcano, Tanzania. The Igwisi Hills kimberlitic olivine grains are compared to phenocrystic olivine, liberated from picritic lavas, and mantle olivine, liberated from a fresh peridotite xenolith. Image analysis, scanning electron microscopy imagery and laser microscopy reveal significant differences in the morphologies and surface features of the three crystal populations. The kimberlitic olivine grains form smooth, rounded to ellipsoidal shapes and have rough flaky micro-surfaces that are populated by impact pits. Mantle olivine grains are characterised by flaked surfaces and indented shapes consistent with growth as a crystal aggregate. Phenocrystic olivine exhibit faceted, smooth-surfaced crystal faces. We suggest that the unique shape and surface properties of the Igwisi Hills kimberlitic olivine grains are products of the transport processes attending kimberlite ascent from mantle source to surface. We infer that the unique shapes and surfaces of kimberlitic olivine grains result from three distinct mechanical processes attending their rapid transport through the thick cratonic mantle lithosphere: (1) penetrative flaking from micro-tensile failure induced by rapid decompression; (2) sustained abrasion and attrition driven by particle-particle collisions between grains within a turbulent, volatile-rich flow regime; and (3) higher-energy particle-particle collisions producing impact cavities superimposed on decompression structures. The combination of these processes during the rapid ascent of kimberlite magmas is responsible for the distinctive ellipsoidal shape of olivine xenocrysts found in kimberlites worldwide.

Jones, T. J.; Russell, J. K.; Porritt, L. A.; Brown, R. J.

2014-05-01

323

Olivine-Pyroxene-PtFe alloy as an oxygen geobarometer  

SciTech Connect

An equilibrium assemblage of olivine, Ca-free pyroxene, and PtFe alloy can be used to calculate oxygen fugacity at a known temperature and pressure. This oxygen geobarometer has been tested T = 1,300-1,450C, P = 1 bar and 10 kbar. The calculated log fO{sub 2} may be compared with that determined by the CO{sub 2}-H{sub 2} mixture used to control the furnace atmosphere in the 1 bar experiments and, in the case of the 10 kbar experiments, the log fO{sub 2} determined from the graphite-fluid equilibrium. The average deviation of the calculated log fO{sub 2} determined from the graphite-fluid equilibrium. The average deviation of the calculated log fO{sub 2} and that determined by other means is 0.2; the maximum absolute difference is 0.4. The distribution coefficient (K{sub d}) for Fe and Mg between coexisting olivine and pyroxene was found to range from 1.14 at x{sub Fe{sub 2}SiO{sub 4}}{sup ol} = 0.164 to 1.54 at x{sub Fe{sub 2}SiO{sub 4}}{sup ol} = 0.655, and varies systematically with the Fe/(Fe + Mg) of the phases.

Jamieson, H.E.; Roeder, P.L.; Grant, A.H. (Queen's Univ., Kingston, Ontario (Canada))

1992-01-01

324

How dynamic recrystallization affects olivine crystal preferred orientations  

NASA Astrophysics Data System (ADS)

Spinel peridotite mantle xenoliths from Persani Mountains, Romania, derived from about a 20 km depth-transect of the shallow subcontinental lithosphere display deformation by dislocation creep accompanied by dynamic recrystallization at continuously varying temperature, strain rate and stress conditions. The continuous variation in deformation conditions allowed us to characterize the effect of dynamic recrystallization on olivine fabric strength, which is the main parameter controlling the anisotropy of physical properties, such as electrical conductivity, seismic wave propagation and thermal diffusivity in the upper mantle. We have defined a dimensionless dispersion factor, which describes the randomization of crystallographic orientations of recrystallized grains with respect to the parental porphyroclasts. This dispersion factor is largely independent of the number of grains analyzed, of the recrystallized grain size, which directly relates to the deviatoric stress, and of the overall fabric strength. This suggests that, for a large range of stress, strain rate and temperature conditions, recrystallization could result in similar dispersion in the orientation of recrystallized grains with respect to the orientation of the parental grains. Consequently, the olivine fabric strength seems to be dominantly controlled by the volume of recrystallized grains, which depends mainly on finite strain, whereas strain rate and temperature conditions act only via grain growth, that tends to counteract the effect of subgrain rotation and strengthen the CPO.

Falus, G.; Tommasi, A.

2009-04-01

325

B-type olivine fabric induced by grain boundary sliding  

NASA Astrophysics Data System (ADS)

Mineral Lattice Preferred Orientation (LPO) in naturally deformed peridotite is typically interpreted to result from the motion of intra-crystalline dislocations during dislocation creep. The degree of mineral alignment (fabric strength) is often assumed to increase with increasing finite strain. Here, we document olivine LPOs in peridotites in a kilometer-scale mantle shear zone in the Ronda massif (Spain) that demonstrate a transition from a flow-parallel [100]-axis LPO (A-type fabric) to a flow-normal [100]-axis LPO (B-type fabric). We conclude that the B-type fabric in the Ronda peridotite results from the enhancement of grain boundary sliding (GBS) with decreasing grain size, rather than a change in the dominant dislocation slip system because: (1) dislocation sub-structures remain consistent with the A-type slip system in all samples; (2) the fabric transition correlates with decreasing fabric strength despite increasing finite strain; (3) the analysis of deformation conditions in Ronda is inconsistent with the experimental conditions, including water content, inferred to promote the dominance of (010)[001] slip in laboratory samples, and (4) our observations are supported by experiments that document B-type fabric in olivine aggregates where deformation involves a component of GBS. Our results have important implications for interpreting the rheological properties of shear zones and upper mantle structures via micro-structural and seismic observations.

Précigout, Jacques; Hirth, Greg

2014-06-01

326

Annealing behaviour of ion tracks in olivine, apatite and britholite  

NASA Astrophysics Data System (ADS)

Ion tracks were created in olivine from San Carlos, Arizona (95% Mg2SiO4), apatite (Ca5(PO4)3(F,Cl,O)) from Durango, Mexico, and synthetic silicates with the apatite structure: Nd8Sr2(SiO4)6O2 and Nd8Ca2(SiO4)6O2 using 1.6 and 2.2 GeV Au ions. The morphology and annealing behaviour of the tracks were investigated by means of synchrotron based small angle X-ray scattering in combination with ex situ annealing. Tracks in olivine annealed above ˜400 °C undergo a significant change in track radius due to recrystallisation of the damage tracks. At temperatures higher than 620 °C, the scattering images indicate fragmentation of the track cylinders into smaller subsections. Ion tracks were annealed at elevated temperatures up to 400 °C in the Durango and Ca-britholite, and up to 560 °C in Sr-britholite. While there was a significant change in the track radii in the Durango apatite, tracks in the two synthetic samples remained almost unchanged.

Afra, B.; Lang, M.; Bierschenk, T.; Rodriguez, M. D.; Weber, W. J.; Trautmann, C.; Ewing, R. C.; Kirby, N.; Kluth, P.

2014-05-01

327

Serpentinization of Olivine by Seawater: A Flow-Through Experiment  

NASA Astrophysics Data System (ADS)

The mantle exposed at slow spreading ridges is pervasively serpentinized, down to ca. 5km according to geophysical data. The onset and durability of this hydration process require efficient penetration and renewal of fluids at the mineral-fluid interface. However, the mechanisms of fluid penetration are still poorly understood. Moreover, serpentinization is exovolumic, if a mass-conservative system is assumed, or chemical elements are leached out to conserve rock volume. Thus, the extent of serpentinization depends of the system capacity to create space and/or to drive mass transfers. In order to investigate these hydrodynamic and chemical mechanisms, we did a laboratory experiment during which seawater was injected in a sintered San Carlos olivine sample at conditions representative of low temperature ultramafic hydrothermal systems. The percolation-reaction experiment was carried out at 19 MPa and 190°C; the initial water flow was set at 0.2 mL/h then decreased down to 0.06 mL/h after 8 days. During the experiment (23 days), permeability decreased continuously. The composition of the outlet fluid varied strongly during the first 24h of the experiment, then reached equilibrium values. The high Si concentrations in outlet fluids indicated steady olivine dissolution, while their low Fe and Mg concentrations suggested precipitation of Fe- and Mg-rich mineral phases. The reacted sample acquired a reddish brown color, indicating oxidation reactions occurred. Optical observation and SEM imaging revealed the presence of a soft white material filling the pores of the reacted sample. It was identified as a poorly crystallized serpentine type material by AEM/TEM analyses. This proto-serpentine is intimately associated to <100 nm Fe-oxide patches (probably hematite) growing on the olivine surface. We interpret the precipitation of this proto-serpentine together with Fe-oxides throughout the sample as marking the early stages of serpentinization. The fluid composition not being modified by changes in fluid flow, we posit that olivine serpentinization is not controlled by elemental transport and/or by chemical kinetics, but takes place at-equilibrium; the reaction velocity is very fast and independent on the changes in the reaction surface area. Indeed, mass balance calculations indicate that more than 15 wt. % olivine was dissolved while the same mass of proto-serpentine was formed; concurrently, porosity decreased from ˜ 12% to 5 %. We infer that the structure of the newly formed proto-serpentine resulted in the clogging of fluid paths and explain the decrease of permeability during experiments. Yet the loose structure of the proto-serpentine allows maintaining a connected pore structure ensuring the perennial renewing (diffusion and/or advection) of the reactants at the reaction surfaces. These experimental results are used to constrain numerical reactive transport models and better understand the scale and efficiency of serpentinization reactions (effective reaction rates in porous/fractured media) at the scale of spreading ridges.

Gouze, P.; Luquot, L.; Andreani, M.; Godard, M.; Gibert, B.

2011-12-01

328

Metastable olivine wedge and deep dry cold slab beneath southwest Japan  

Microsoft Academic Search

Oceanic plates subducted at trenches penetrate into the deep mantle, and encounter a structural boundary at a depth of 410km where olivine, the dominant element of mantle rocks, transforms into a higher density form wadsleyite. This transformation may be delayed within the coldest core of subducting plates (slabs) due to kinetic effects, and it has been suggested that metastable olivine

Hitoshi Kawakatsu; Shoichi Yoshioka

2011-01-01

329

Hydrous olivine unable to account for conductivity anomaly at the top of the asthenosphere  

NASA Astrophysics Data System (ADS)

The oceanic asthenosphere is observed to have high electrical conductivity, which is highly anisotropic in some locations. In the directions parallel and normal to the plate motion, the conductivity is of the order of 10-1 and 10-2Sm-1, respectively, which cannot be explained by the conductivity of anhydrous olivine. But because hydrogen can be incorporated in olivine at mantle pressures, this observation has been attributed to olivine hydration, which might cause anisotropically high conductivity by proton migration. To examine this hypothesis, here we report the effect of water on electrical conductivity and its anisotropy for hydrogen-doped and undoped olivine at 500-1,500K and 3GPa. The hydrous olivine has much higher conductivity and lower activation energy than anhydrous olivine in the investigated temperature range. Nevertheless, extrapolation of the experimental results suggests that conductivity of hydrous olivine at the top of the asthenosphere should be nearly isotropic and only of the order of 10-2Sm-1. Our data indicate that the hydration of olivine cannot account for the geophysical observations, which instead may be explained by the presence of partial melt elongated in the direction of plate motion.

Yoshino, Takashi; Matsuzaki, Takuya; Yamashita, Shigeru; Katsura, Tomoo

2006-10-01

330

Olivine and Carbonate Globules in ALH84001: A Terrestrial Analog, and Implications for Water on Mars  

NASA Astrophysics Data System (ADS)

Low-temperature carbonate globules in ALH84001 are found near olivine grains that equilibrated at T>800° C. Terrestrial analogs from Spitsbergen (Norway) suggest an explanation of this association; the carbonate globules may have been deposited in cavities where olivine had been dissolved out.

Treiman, A. H.

2005-03-01

331

The Iron, Magnesium, and Calcium Distribution in Coexisting Olivines and Rhombic Pyroxenes of Chondrites  

Microsoft Academic Search

Iron, magnesium, and calcium in olivines and pyroxenes of 95 chondritic meteor- ites were analyzed with an electron microprobe. Of these, 86 were 'ordinary' chondrites, each having constant iron-magnesium ratios in olivine and pyroxene. Between different meteorites these ratios vary within three narrow ranges which reflect the It- and L-group chondrites, as well as a third group, designated the LL

Klaus Keil; Kurt Fredriksson

1964-01-01

332

Systematics of Ni, Co, Cr and V in Olivine from Planetary Melt Systems: Martian Basalts  

NASA Technical Reports Server (NTRS)

Secondary Ion Mass Spectrometry (SIMS) data for Ni, Co, Cr, and V in olivine in martian basalts is compared to data from lunar and terrestrial basalts. We use experimentally-derived and published D values to calculate as-yet unsampled, olivine-bearing, non-cumulus melt compositions. Additional information is contained in the original extended abstract.

Herd, C. D. K.; Jones, J. H.; Shearer, C. K.; Papike, J. J.

2001-01-01

333

High-temperature condensation of iron-rich olivine in the solar nebula  

Microsoft Academic Search

The origin of oxidized iron in chondritic meteorites is a fundamental problem in meteoritics. Conventional models of meteorite formation assume FeO incorporation into olivine and pyroxene at around 500 K. There is evidence that at least some fayalitic olivine in Allende must have formed by condensation. Thermodynamic equilibrium calculations presented here define the nebular conditions that would enable condensation of

Herbert Palme; Bruce Fegley Jr.

1990-01-01

334

Olivines in the Egersund Dikes (SW Norway): Evidence for the Evolutionary History of Neoproterozoic Tholeiitic Magmas.  

NASA Astrophysics Data System (ADS)

The Neoproterozoic Egersund dikes in Sw Norway intruded at 650-600 Ma, and the majority formed by intrusion of olivine tholeiites and tholeiites that are geochemically similar to modern OIB. The olivine tholeiites are remarkably well preserved, with glassy chilled margins that contain olivine and plagioclase. Olivines show a range of textural and compositional characteristics that potentially provide information about the evolutionary history of the magmas. Olivine microphenocrysts in the chilled margins are euhedral, and sometimes skeletal indicating rapid cooling. Their compositions (Fo80-82) are appropriate for equilibrium with the host melt at oxygen fugacities 0-1 log unit below QFM. Resorbed macrocrysts are more magnesian (Fo0.82-0.84) than the microphenocrysts and are similar in composition to olivines in the centers of the dikes. The latter include skeletal crystals (mostly less than 1mm), strained crystals, and crystals intergrown with plagioclase. Skeletal crystals with compositions of about Fo84 could have been in equilibrium with magmas corresponding in composition to the nearly aphyric centers of some dikes at 0-1 log unit below FMQ. These crystals are interpreted as high-pressure phenocrysts that formed in magma chambers near the base of the crust (about 30km). The centers and chilled margins of the dikes have compositions consistent with evolution along the Ol-Cpx-Plag cotectic at 0.8-1 Gpa. The compositions of larger, strained olivines (up to 3mm) and olivines intergrown with plagioclase are interpreted to be xenocrysts derived from the wall rocks through which the magma ascended. This interpretation is supported by the presence of reverse-zoned olivines with relatively Fe-rich (Fo0.76) cores that are strained or are intergrown with plagioclase. The overall compositional similarity between the majority of the xenocrystal olivines and the skeletal olivines (high-pressure phenocrysts) suggests that the former might have formed by crystallization of earlier batches of olivine tholeiite magma. It is clear that olivines in the Neoproterozoic Egersund dikes provide evidence for a complex evolutionary history similar to that proposed for recent Kilauean olivine tholeiites.

Karen, T. S.; Barton, M.; Miller, C. A.

2003-12-01

335

Fine, nickel-poor Fe-Ni grains in the olivine of unequilibrated ordinary chondrites  

NASA Astrophysics Data System (ADS)

Nickel-poor Fe-Ni grains smaller than 2.0 microns are common inclusions in ordinary, unequilibrated chondrites' porphyritic chondrule olivine, where the olivine grains seem to be relicts that survived chondrule formation without melting. This 'dusty' metal, whose most common occurrence is in the core of olivine grains having clear, Fe-poor rims, appears to be the product of the in situ reduction of FeO from the host olivine, with H2 or carbonaceous matter being the most likely reductants. H2 may have been implanted by solar wind or solar flare irradiation, but this requires the dissipation of nebular gas before the end of the chondrule formation process. Carbonaceous matter may have been implanted by shock. The large relict olivine grains may be nebular condensates or fragments broken from earlier chondrule generations.

Rambaldi, E. R.; Wasson, J. T.

1982-06-01

336

The x ray microprobe determination of chromium oxidation state in olivine from lunar basalt and kimberlitic diamonds  

NASA Technical Reports Server (NTRS)

The synchrotron x-ray microprobe is being used to obtain oxidation state information on planetary materials with high spatial resolution. Initial results on chromium in olivine from various sources including laboratory experiments, lunar basalt, and kimberlitic diamonds are reported. The lunar olivine was dominated by Cr(2+) whereas the diamond inclusions had Cr(2+/Cr(3+) ratios up to about 0.3. The simpliest interpretation is that the terrestrial olivine crystallized in a more oxidizing environment than the lunar olivine.

Sutton, S. R.; Bajt, S.; Rivers, M. L.; Smith, J. V.

1993-01-01

337

Extended planar defects and the rapid incorporation of Ti4+ into olivine  

NASA Astrophysics Data System (ADS)

The formation of extended planar defects in minerals such as olivine is related to high point defect concentration and can be driven by large gradients in chemical potential, where the energy of the system is lowered by the ordering of defects along specific planes in the crystal. The presence of extended defects has the potential to create the (apparently) anomalous ionic diffusion in olivine as reported recently (Spandler and O'Neill in Contrib Mineral Petrol 159(6):791-818, 2010). High-resolution transmission electron microscopy and energy-filtered imaging were done using experimental samples designed to examine the impact of a TiO2 and f O2 on the potential to form such defects in ferromagnesian olivine. Doped basalt (5 wt% TiO2)-olivine reaction couple experiments were run at 1 atm and 1,310 and 1,410 °C for 50 h at various f O2, ranging from 102 below to 102 above the quartz-fayalite-magnetite buffer. Our results show that extended planar defects in olivine, parallel to {101}ol and occurring in ordered "clusters" with a prolate spheroid geometry 5-25 nm across and extending up to 150 nm into the olivine, are present near the olivine-glass interfaces in all of our experimental high-TiO2 basalt-olivine samples. Increased Ti content in the olivine is associated with the defects; ordering of Ti4+ and octahedral site vacancies leads to a two- or three-layer superstructure in the olivine. Defect nucleation and growth is driven by the large TiO2 chemical potential gradient across the phase boundary at the start of the experiments, which provides access to microstructures not otherwise present.

Burgess, Katherine D.; Cooper, Reid F.

2013-10-01

338

Calibrations of phase abundance, composition, and particle size distribution for olivine-orthopyroxene mixtures from reflectance spectra  

NASA Technical Reports Server (NTRS)

An analytical method for quantifying the characteristics (phase abundances, phase composition, and grain size) of an olivine-orthopyroxene mixture from reflectance spectra is described. The spectral parameters related to reflectance, wavelength position, and albedo are investigated; the absorption bands for the olivine-orthopyroxene mixture is also studied. Primary calibrations useful for the determination of the olivine-orthopyroxene mixture characteristics are examined.

Cloutis, Edward A.; Gaffey, Michael J.; Jackowski, Timothy L.; Reed, Kevin L.

1986-01-01

339

Origin of plagioclase-olivine inclusions in carbonaceous chondrites  

NASA Astrophysics Data System (ADS)

The origin of plagioclase-olivine inclusions (POIs) from three CV chondrites and one ungrouped chondrite was investigated by examining the chemical, mineralogical, and isotopic characteristics of a group of POIs from these chondrites. Results of these analyses demonstrate that the mixing and the partial melting processes in these inclusions were superimposed on more ancient isotopically heterogeneous material. A comparison of the essential characteristics of POIs and CAIs suggests that the major processes leading to the formation of POIs (such as condensation, dust/gas fractionation, aggregation of chemically and isotopically disparate materials, and partial melting) are common to most CAIs and chondrules. A scenario for the origin of POIs is proposed, showing that the homogeneity of the final assemblage (whether a POI, a CAI, or a chondrite) is primarily a reflection of the thermal history rather than the nature of precursor materials.

Sheng, Y. J.; Hutcheon, I. D.; Wasserburg, G. J.

1991-02-01

340

Collisional Processing of Comet Surfaces: Impact Experiments into Olivine  

NASA Technical Reports Server (NTRS)

A new paradigm has emerged where 3.9 Ga ago, a violent reshuffling reshaped the placement of small bodies in the solar system (the Nice model). Surface properties of these objects may have been affected by collisions caused by this event, and by collisions with other small bodies since their emplacement. In addition, objects in the Kuiper Belt are believed to undergo extensive collisional processing while in the Kuiper Belt. Physical manifestations of shock effects (e.g., planar dislocations) in minerals typically found in comets will be correlated with spectral changes (e.g. reddening, loss and shift of peaks, new signatures) to allow astronomers to better understand geophysical impact processing that has occurred on small bodies. Targets will include solid and granular olivine (forsterite), impacted over a range of impact speeds with the Experimental Impact Laboratory at NASA JSC. Analyses include quantification of the dependence of the spectral changes with respect to impact speed, texture of the target, and temperature.

Lederer, S. M.; Jensen, E. A.; Cintala, M. J.; Smith, D. C.; Nakamura-Messenger, K.; Keller, L. P.; Wooden, D. H.; Fernandez, Y. R.; Zolensky, M. E.

2011-01-01

341

Additional Sr Isotopic Heterogeneity in Zagami Olivine-Rich Lithology  

NASA Technical Reports Server (NTRS)

Prior isotopic analyses of Zagami have established differing initial Sr-87/Sr-86 (ISr) ratios of among Zagami lithologies, fine-grained (FG), coarse-grained (CG), and dark mottled lithologies (DML)]. The Zagami sample (KPM-NLH000057) newly allocated from the Kanagawa Prefectural Museum of Natural History contained DML and the Ol-rich lithology which included more ferroan olivines (Ol-rich: Fa(sub 97- 99) vs late-stage melt pockets: Fa(sub 90-97)]). We have combined mineralogy-petrology and Rb-Sr isotopic studies on the Kanagawa Zagami sample, which will provide additional clues to the genesis of enriched shergottites and to the evolution of Martian crust and mantle

Misawa, K.; Niihara, T.; Shih, C.-Y; Reese, Y. D.; Nyquist, L. E.; Yoneda, S.; Yamashita, H.

2012-01-01

342

Infrared spectra of olivine polymorphs - Alpha, beta phase and spinel  

NASA Technical Reports Server (NTRS)

The infrared absorption spectra of several olivines (alpha phase) and their corresponding beta phase (modified spinel) and spinel (gamma) high-pressure polymorphs are determined. Spectra were measured for ground and pressed samples of alpha and gamma A2SiO4, where A = Fe, Ni, Co; alpha and gamma Mg2GeO4; alpha Mg2SiO4; and beta Co2SiO4. The spectra are interpreted in terms of internal, tetrahedral and octagonal, and lattice vibration modes, and the spinel results are used to predict the spectrum of gamma Mg2SiO4. Analysis of spectra obtained from samples of gamma Mg2GeO4 heated to 730 and 1000 C provides evidence that partial inversion could occur in silicate spinels at elevated temperatures and pressures.

Jeanloz, R.

1980-01-01

343

Martian Dunite NWA 2737: Petrographic Constraints on Geological History, Shock Events, and Olivine Color  

SciTech Connect

Meteorite Northwest Africa (NWA) 2737 is the second known chassignite, an olivine-rich igneous rock with mineral compositions and isotopic ratios that suggest it formed on Mars. NWA 2737 consists of ?85% vol. olivine (Mg, molar Mg/(Mg + Fe), of 78.3 {+-} 0.4%), which is notable because it is black in hand sample and brown in thin section. Other minerals include chromite, pyroxenes (augite, pigeonite, orthopyroxene), and diaplectic glass of alkali-feldspar composition. Aqueous alteration is minimal and appears only as slight dissolution of glass. NWA 2737 formed by accumulation of olivine and chromite from a basaltic magma; the other minerals represent magma trapped among the cumulus grains. Minerals are compositionally homogeneous, consistent with chemical equilibration in late and postigneous cooling. Two-pyroxene thermometry gives equilibration temperatures 1150 C, implying a significant time spent at the basalt solidus. Olivine-spinel-pyroxene equilibria give ?825 C (possibly the T of mesostasis crystallization) at an oxidation state of QMF-1. This oxidation state is consistent with low Fe3+ in olivine (determined by EMP, Moessbauer spectra, and synchrotron micro-XANES spectroscopy) and with {approx}10% of the iron in pyroxene being Fe3+. NWA 2737 experienced two shock events. The first shock, to stage S5-S6, affected the olivine by producing in it planar deformation features, intense mosaicism and lattice strain, and abundant droplets of iron-nickel metal, 5-15 nm in diameter. At this stage the olivine became deeply colored, i.e., strongly absorbing at visible and near-infrared (NIR) wavelengths. This shock event and its thermal pulse probably occurred at {approx}170 Ma, the Ar-Ar age of NWA 2737. The colored olivine is cut by ribbons of coarser, uncolored olivine with long axes along [100] and shorter axes on {l_brace}021{r_brace} planes: These are consistent with the easy slip law for olivine [100]{l_brace}021{r_brace}, which is activated at moderate strain rate at high temperature. Within these ribbons the olivine was coarsened and the iron metal globules coalesced to micron-sized grains. The ribbons also are mosaicized and cut by planar fractures, which bespeak a second shock event, possibly that of ejection from Mars. The deeply colored olivine in NWA 2737 is unusual and represents a new 'ground truth' type for remote sensing of Mars. Understanding the occurrence of the brown color in olivine in NWA 2737 places important constraints on interpretation of optical measurements.

Treiman,A.; Dyar, M.; McCanta, M.; Noble, S.; Pieters, C.

2007-01-01

344

The influence of water on the Peierls stress of olivine at high pressures  

NASA Astrophysics Data System (ADS)

To investigate the influence of water on the low-temperature plasticity of olivine under lithospheric conditions, we carried out a series of creep experiments on polycrystalline olivine at high pressures (~6 GPa), relatively low temperatures (873 ? T ? 1173 K), and hydrous conditions using a deformation-DIA. Samples were fabricated from fine powdered San Carlos olivine under hydrous conditions. In the experiments, a sample column composed of a sample and alumina pistons was assembled with a talc sleeve and graphite resistance heater into a 6.2-mm edge length cubic pressure medium. Experiments were carried out at the National Synchrotron Light Source at Brookhaven National Laboratory. In a run, differential stress and sample displacement were monitored in-situ using synchrotron x-ray diffraction and radiography, respectively. The low-temperature plasticity of olivine under hydrous conditions is constrained by our data with a Peierls stress of 4.2 ± 0.3 GPa. This value is much lower than those reported the Peierls stress for olivine under anhydrous conditions (~ 6 - 15 GPa, Evans and Goetze, 1979; Raterron et al., 2004; Mei at al., 2010), indicating a significant influence of water on the low-temperature plasticity of olivine. The low-temperature flow behavior of olivine under hydrous conditions quantified in this study provides a necessary constraint for modeling the dynamic activities occurring within lithospheric mantle especially for those regions with the presence of water such as beneath a mid-ocean ridge and along a subducting slab.

Mei, S.; Suzuki, A. M.; Xu, L.; Kohlstedt, D. L.; Dixon, N. A.; Durham, W. B.

2012-04-01

345

Oxygen isotopic composition of individual olivine grains from the Allende meteorite  

NASA Technical Reports Server (NTRS)

The oxygen isotopic composition of a variety of individual olivine grains (including refractory forsterite grains, cores of isolated olivine grains, FeO-rich rims, and individual matrix olivine grains) from the Allende CV3 meteorite was investigated by ion microprobe mass spectrometry, in order to obtain information on the formation mechanism of these samples. It was found that the most primitive (i.e., refractory) olivine in Allende is far less enriched in O-16 than are spinel and pyroxene in Ca,Al-rich inclusions, suggesting that Allende olivine must have formed in an environment that is less enriched in O-16 compared to the gas from which Ca,Al-inclusions are formed. FeO-rich (26-30 wt pct) rims of isolated olivine grains are significantly higher in delta-O-17 and delta-O-18 than forsteritic cores, suggesting that these rims formed by condensation from an oxidized gas with higher delta-O-17 than delta-O-18. Matrix olivine was found to be highest in FeO and to have the lowest enrichment in O-16.

Weinbruch, S.; Zinner, E. K.; El Goresy, A.; Steele, I. M.; Palme, H.

1993-01-01

346

Olivine-dominated asteroids and meteorites: Distinguishing nebular and igneous histories  

NASA Astrophysics Data System (ADS)

Melting models indicate that the composition and abundance of olivine systematically co-vary and are therefore excellent petrologic indicators. However, heliocentric distance, and thus surface temperature, has a significant effect on the spectra of olivine-rich asteroids. We show that composition and temperature complexly interact spectrally, and must be simultaneously taken into account in order to infer olivine composition accurately. We find that most (7/9) of the olivine-dominated asteroids are magnesian and thus likely sampled mantles differentiated from ordinary chondrite sources (e.g., pallasites). However, two other olivine-rich asteroids (289 Nenetta and 246 Asporina) are found to be more ferroan. Melting models show that partial melting cannot produce olivine-rich residues that are more ferroan than the chondrite precursor from which they formed. Thus, even moderately ferroan olivine must have non-ordinary chondrite origins, and therefore likely originate from oxidized R chondrites or melts thereof, which reflect variations in nebular composition within the asteroid belt. This is consistent with the meteoritic record in which R chondrites and brachinites are rare relative to pallasites.

Sunshine, Jessica M.; Bus, Schelte J.; Corrigan, Catherine M.; McCoy, Timothy J.; Burbine, Thomas H.

2007-08-01

347

The composition of mesosiderite olivine clasts and implications for the origin of pallasites  

NASA Technical Reports Server (NTRS)

The composition of olivine clasts from the mesosiderites Emery, Mincy and Pinnaroo is investigated, and implications of the results for the origin of the pallasites, which, although chemically distinct, may be related to the diogenites, eucrites, howardites and mesosiderites, are discussed. Centimeter-sized olivines were analyzed by electron microprobe, and instrumental neutron activation analysis was performed on one olivine each from Emery and Pinnaroo and an olivine separate from the Brenham pallasite. The olivine compositions are found to range from Fa8 to Fa28, with Emery samples having values from Fa18 to Fa28, and to require essentially total melting of a source composition rich enough in FeO to produce basaltic clasts. It is argued that the mesosiderite olivines were formed in the outer few kilometers of their parent body, as were those of the pallasites, which have the same compositions as the mesosiderite olivines. A model is then developed for the origin of the pallasites as a by-product of igneous differentiation in the external heating of a chondritic parent body.

Mittlefehldt, D. W.

1980-01-01

348

Effect of Sulfur on Siderophile Element Partitioning Between Olivine and Martian Primary Melt  

NASA Technical Reports Server (NTRS)

Since olivine is a common early crystallizing phase in basaltic magmas that have produced planetary and asteroidal crusts, a number of experimental studies have investigated elemental partitioning between olivine and silicate melt [e.g., 1, 2, 3]. In particular, olivine/melt partition coefficients of Ni and Co (DNi and DCo) have been intensively studied because these elements are preferentially partitioned into olivine and thus provide a uniquely useful insight into the basalt petrogenesis [e.g., 4, 5]. However, none of these experimental studies are consistent with incompatible signatures of Co [e.g., 6, 7, 8] and Ni [7] in olivines from Martian meteorites. Chemical analyses of undegassed MORB samples suggest that S dissolved in silicate melts can reduce DNi up to 50 % compared to S-free experimental systems [9]. High S solubility (up to 4000 ppm) for primitive shergottite melts [10] implies that S might have significantly influenced the Ni and Co partitioning into shergottite olivines. This study conducts melting experiments on Martian magmatic conditions to investigate the effect of S on the partitioning of siderophile elements between olivine and Martian primary melt.

Usui, T.; Shearer, C. K.; Righter, K.; Jones, J. H.

2011-01-01

349

Deformation microstructures and water content of olivine in peridotite from the Lindås Nappe, Bergen Arc, western Norway  

NASA Astrophysics Data System (ADS)

Two peridotite outcrops in Lindas Nappe anorthosite complex, Bergen Arc, western Norway were studied to understand deformation microstructures of olivine. A mylonite zone was found in the peridotites and deformation fabrics of recrystallized olivine in the area were also studied. Lattice preferred orientation (LPO) of olivine was determined using electron backscattered diffraction (EBSD) in SEM. Water content of olivine in the samples was measured using the Fourier transformation infrared (FTIR) spectroscopy and small inclusions inside olivine and pyroxene grains were identified by using Micro-Raman spectroscopy. We observed various types of LPOs of olivine in wall rock area. A sample (372) showed that [100] axes of olivine are aligned subparallel to the lineation and [001] axes aligned normal to the foliation, which is known as E-type LPO of olivine (Jung et al., 2006). Most of other samples in wall rock showed a combination of two different types of LPOs: both [100] and [001] axes were aligned parallel to the lineation, and [010] axes were aligned normal to foliation plane. This is a combination of A- and B-type LPO of olivine. In the mylonite area, we discovered that there is a change in LPO of olivine from wall rock to mylonite. We observed olivine fabrics of B-, C-type LPO and a combination of B- and C-type LPO of olivine. The wall rock fabric is Grenvillian in age (ca 1000 Ma) while the ultramylonite zone is Caledonian (ca 400 Ma). Spinel is also present in the wall rock while small garnets have been found around the spinel in the mylonite zone. This suggests that the fabric in the wall rock developed in the spinel lherzolite field while the mylonite fabric evolved under garnet lherzolite conditions. FTIR analysis of olivine revealed that olivine in wall rock contains about 300 ppm H/Si of water content, while olivine in mylonite zone contains over 700 ppm H/Si, showing water content of olivine in mylonite area was much higher than that in wall rock area. In addition, we also found amosite and antigorite in mylonite area. These observations indicate that olivine fabric difference between wall rock and mylonite was caused by water. We observed a strong LPO and high dislocation density of olivine in wall rock area, indicating that dominant deformation mechanism of olivine in wall rock was dislocation creep. On the other hand, we found a weak LPO, low dislocation density of olivine and four grain junctions in the mylonite area which are indicative of enhanced grain boundary sliding.

Jung, S.; Jung, H.; Austrheim, H.

2011-12-01

350

Timescales for Reequilibration of Major Elements in Olivine-Hosted Melt Inclusions  

NASA Astrophysics Data System (ADS)

Geochemical evidence demonstrates that near-fractional partial melts form over a range of upper mantle conditions from peridotites with variable bulk compositions. The importance of determining the initial compositions of melt inclusions lies in the ability of the major elements to record information about the conditions at which melt generation takes place, and the involvement of exotic lithologies in the melt generation process. However, before the major-element compositions of melt inclusions can be interpreted reliably, the effects of post-entrapment processes must be quantitatively understood. Diffusive reequilibration of olivine-hosted melt inclusions during cooling, magma mixing, or decompression can produce irreversible compositional changes in response to changes to the melt outside of the host olivine. Factors that influence the timescales for reequilibration of major elements in olivine-hosted melt inclusions are the sizes of the inclusion and the host olivine, which control the diffusion lengthscale, and the olivine-melt partition coefficient and diffusivity, which control the flux through the olivine grain. Among the major elements, Fe, Mg and Ca have the greatest potentials for undergoing diffusive reequilibration. The concentration of H2O in olivine-hosted melt inclusions must also be evaluated with care. Based on experimentally determined diffusivities and partition coefficients, reequilibration of Fe and Mg occurs on a timescale of years, while Ca reequilibrates over a few decades. Diffusion of H in olivine is rapid enough to allow reequilibration in a matter of hours. Important questions the must be answered in order to fully assess the reliability of the melt inclusion compositions are whether the history of Fe/Mg transport through the olivine can be uniquely determined, whether there are factors that rate limit transport of H, and whether gradients in slower diffusing elements can be used to constrain re-equilibration timescales.

Gaetani, G. A.; Hauri, E. H.

2008-12-01

351

Granoblastic olivine aggregates as precursors of Type I chondrules: An experimental test  

NASA Astrophysics Data System (ADS)

Chondrule formation models involving precursors of granoblastic olivine aggregates (GOA) of either planetesimal or nebular origin have recently been proposed. We have therefore conducted chondrule simulation experiments using mixtures of 100 h-thermally annealed GOA and An + En to test the viability of GOA as predecessors of porphyritic olivine (PO) chondrules. Isothermal runs of less than 5 min at 1350-1550 °C result in GOA disaggregation and Fe-Mg exchange; runs of 0.5-4 h show textures superficially similar to granular and PO chondrules, but with reversely zoned olivine. Charges isothermally heated at 1550 °C for 1 and 4 h before being cooled at 10 and 100 °C/h undergo olivine crystallization and yield classical PO textures. Although most evidence of origin from GOA is erased, the cores of normally zoned euhedral crystals are relict. As 'phenocrysts' in Type I chondrules can be relict such chondrules could have experienced similar peak temperatures to those of Type II chondrules. Chondrules containing GOA with olivine triple junctions resemble experimental charges heated for minutes at temperatures between 1350 and 1450 °C and Type I chondrules with subhedral to anhedral olivine plus GOA relicts resemble charges heated at the same temperatures but for longer duration. Type I chondrules with a mass of granular olivine or irregular, anhedral olivine grains in the center, and much glass nearer the margin, on the other hand, require limited heating at high temperature (1550 °C) while Type I chondrules with euhedral olivines, resemble charges heated at 1550 °C for 4 h. The majority of Type I chondrules in CV chondrites display evidence of derivation from GOA. Many finer-grained chondrules in CR and UOC on the other hand, could not have been derived from such coarse-grained precursors, but could have formed from fine-grained dustballs as stipulated in the standard paradigm. Thus, both GOA and dustballs represent viable chondrule precursors of coarser and finer-grained Type I PO chondrules, respectively.

Whattam, Scott A.; Hewins, Roger H.

2009-09-01

352

Minor and trace elements in olivines as probes into early igneous and mantle melting processes  

NASA Astrophysics Data System (ADS)

The trace element composition of olivine is a rapidly growing research area that has several applications of great potential. Mantle olivines can be distinguished from volcanic olivines by lower concentrations of Ca (<700 ppm), Ti (<70 ppm), and often Cr. The melting of pyroxenites derived from recycled ocean crust can be recognized in volcanic olivines by correlations of Mn, Al, Sc and Co in addition to Ni. High Ni is characteristic of olivine derived from olivine-free source rocks, but alone it does not distinguish between recycling of ocean crust, continental crust, mantle wedge hybridization, and intra-mantle melt migration. Trace elements help to identify different types of non-peridotitic ultramafic rocks, including those not formed by ocean crust recycling. High Li may be caused by recycling of continental crust, as in Mediterranean post-collisional volcanics or by interaction with carbonatitic melts, and correlation with further elements such as Zn, Na, Ti and Ca will help to identify minerals in the source assemblages, such as phlogopite, spinel, garnet, amphiboles and carbonates, and thus the source of the olivine-free assemblages. Olivines often store the earliest chemical signals of melt loss in peridotites, but later absorb trace elements from passing melts, and are thus excellent monitors of the chemistry of metasomatic agents. Trace elements distinguish between Ti-enrichment by silicate melt metasomatism (high Ti, low Ca) and high-Ca signatures associated with plumes and rift regions that may be due to carbonate-silicate melts. Li may be enriched in olivine in the orogenic mantle, indicating the involvement of melted continental crustal material. Experimental data on element partitioning and diffusion currently partly conflicts with information from natural rocks.

Foley, Stephen F.; Prelevic, Dejan; Rehfeldt, Tatjana; Jacob, Dorrit E.

2013-02-01

353

Fe-Mg-Mn relations of ureilite olivines and pyroxenes and the genesis of ureilites  

NASA Astrophysics Data System (ADS)

Microprobe analyses of ureilite and pigeonite cores are studied. The Fe/Mn-Fe/Mg relationship in the olivine core is examined. It is observed that magnetic processs such as fractional crystallization and partial melting, and FeO reduction contribute to the olivine core composition. The study of the Mg/Mn and Fe/Mn distributions reveals that these two distributions are not in equilibrium in the olivine and pigeonite cores. The effect of a reducing agent, carbon, on the ureilite genesis is investigated. It is concluded that fractional crystallization and FeO reduction are the major processes of ureilite genesis.

Mittlefehldt, D. W.

1986-01-01

354

Serpentinization of oceanic peridotites: 2. Kinetics and processes of San Carlos olivine hydrothermal alteration  

NASA Astrophysics Data System (ADS)

The kinetics of the reaction (Mg,Fe)-olivine + H2O ? serpentine + magnetite + brucite + H2 were investigated at 500 bars in the 250-350°C range using natural olivine (San Carlos; Fo91) with grain sizes between 1 and 150 ?m and for run durations up to 514 d. The amount of magnetite produced, which directly relates to reaction progress, was accurately monitored using up to 24 time-resolved magnetic measurements per experiment. Eighty percent of serpentinization was achieved after 60 d for olivine grain sizes of 5-15?m and after 500 d for grain sizes of 50-63 ?m. Serpentinization kinetics were found to be inversely proportional to the geometrical surface area of the starting olivine grains. They were one or two orders of magnitude slower than serpentinization kinetics commonly used for modeling serpentinization-related processes. The nature of the serpentine mineral product depended on the initial olivine grain size (IGS); for IGS in the 5-150?m range lizardite formed, and olivine dissolution was the rate-limiting process. At IGS below 5?m, chrysotile crystallized instead of lizardite, and the relationship between olivine surface area and reaction kinetics no longer held. We infer that for such small olivine grain sizes dissolution is no longer the rate-limiting process. Serpentinization in our experiments was associated with the creation of new reactive surface area according to two cooperative processes: etch pits formation associated with dissolution and grain fracturing for IGS above 20?m. Interestingly, fractures and etch pits with similar geometry and sizes were also observed for residual olivine (with a typical grain size of 50 ?m) in serpentinized peridotite samples from the Southwest Indian Ridge. This suggests that the processes governing olivine serpentinization kinetics in our experiments are similar to those prevailing in natural systems. We therefore suggest that the new kinetic data set that we present here, which encompasses a range of olivine grain sizes and reaction temperatures, is relevant to the serpentinization of olivine in the oceanic crust insofar as water is available.

Malvoisin, Benjamin; Brunet, Fabrice; Carlut, Julie; RouméJon, StéPhane; Cannat, Mathilde

2012-04-01

355

Oriented chromite-diopside symplectic inclusions in olivine from lunar regolith delivered by "Luna-24" mission  

NASA Astrophysics Data System (ADS)

Calcium-chromium rich lamellae in olivine grain No. 1611 from the Luna-24 regolith were studied with FEG-EMPA and TEM. The lamellae consist of a worm-like intergrowth of FeCr2O4 chromite (Chr) and CaMgSi2O6 diopside (Di), with a Chr:Di modal proportion of 1:3. The linear extension of the lamellae and crystallographic orientation relationships among the symplectite phases and the olivine suggest that the lamellae nucleated at deformation defects in the olivine host. Calcium depletion haloes surrounding the lamellae amount to about 75 ?m and indicate that the chromite + diopside lamellae were formed by segregation of calcium and chromium from the host olivine into the lamellae without addition of calcium and/or chromium from outside the olivine. The segregation of calcium and chromium and, consequently, the growth of the symplectic lamellae were diffusion-controlled. The segregation of a calcium-chromium component from the host olivine was associated with oxidation of divalent to trivalent chromium. Oxidation was facilitated by dehydrogenation, which was driven by decompression and/or a change in redox potential. Hydrogen point defects in the original olivine with H+ substituting for divalent cations on the M-sites provided the necessary electron acceptors for the oxidation of chromium and after electron transfer left olivine as molecular H2. The internal microstructure of the lamellae suggests that exsolution of the calcium-chromium rich lamellae from the host olivine and formation of the chromite-diopside symplectic intergrowth occurred simultaneously. The time scale derived from diffusion modeling of the calcium depletion haloes around the lamellae indicates a thermal event on the order of several months to several hundred years at most. Symplectic inclusions found in olivine from lunar, martian and terrestrial rocks are similar with respect to their shape, crystallographic orientation relationships, and internal microstructure of the spinel-clinopyroxene intergrowth. These features are inconsistent with "dry" olivine oxidation that is by the uptake of oxygen. Dehydrogenation of OH-bearing precursor olivine is suggested as a general mechanism of oxidation accompanied by chemical segregation and phase separation resulting in symplectite formation.

Khisina, N. R.; Wirth, R.; Abart, R.; Rhede, D.; Heinrich, W.

2013-03-01

356

Olivines in the Kaba carbonaceous chondrite and constraints on their formation  

NASA Technical Reports Server (NTRS)

Kaba is unique in containing almost pure fayalitic olivine (Fo(sub 0.1)). Its coexistence with pure forsterite up to Fo(sub 99.6) and normal (Fo(sub 92) to Fo(sub 59)) and reversely (Fo(sub 0.4) to Fo(sub 4.7)) zoned olivines suggest that the Kaba olivines are in thermodynamic disequilibrium and experienced a complicated history. The fayalite is sufficiently pure that it is unlikely that it could have been produced by fractional crystallization. A gas-solid reaction under oxidizing conditions (H2O/H2 ratio approximately 10) is probably responsible for its formation.

Hua, X.; Buseck, P. R.

1993-01-01

357

Cellular Precipitates Of Iron Oxide in Olivine in a Stratospheric Interplanetary Dust Particle  

NASA Technical Reports Server (NTRS)

The petrology of a massive olivine-sulphide interplanetary dust particle shows melting of Fe,Ni-sulphide plus complete loss of sulphur and subsequent quenching to a mixture of iron-oxides and Fe,Ni-metal. Oxidation of the fayalite component in olivine produced maghemite discs and cellular intergrowths with olivine and rare andradite-rich garnet. Cellular reactions require no long-range solid-state diffusion and are kinetically favourable during pyrometamorphic oxidation. Local melting of the cellular intergrowths resulted in three dimensional symplectic textures. Dynamic pyrometamorphism of this asteroidal particle occurred at approx. 1100 C during atmospheric entry flash (5-15 s) heating.

Rietmeijer, Frans J. M.

1996-01-01

358

Cr, Mn, and Ca distributions for olivine in angritic systems: Constraints on the origins of Cr-rich and Ca-poor core olivine in angrite LEW87051  

NASA Technical Reports Server (NTRS)

Angrite meteorites are a type of basaltic achondrites that are noted for their very old cyrstallization ages (4.55 b.y.) and unusual chemical and mineralogical properties. In spite of great interest, only four angrites have been found. LEW87051 is the smallest one which weighs 0.6 g. It is a porphyritic rock with coarse subhedral to euhedral olivines set in a fine-grained groundmass which clearly represents a crystallized melt. The largest uncertainty about the petrogenesis of LEW87051 is the relationship between the large olivine crystals and the groundmass. Prinz et al. suggests that olivines are xenocrysts, while McKay et al. proposed a fractional cyrstallization model based on experimental studies. However, the crystals have Cr-rich and Ca-poor cores which do not match experimental olivines. Although Jurewicz and McKay tried to explaine the zoning of the rim by diffusion, some features are not explained. There also exists a definite composition boundary of Fe(2+) and MnO between the core and the rim. To clarify the origin of these olivines, we have performed experiments using LEW87051 analogs to measure the effects of oxygen fugacity on distribution coefficients of various elements in an angritic system.

Mikouchi, T.; Mckay, G.; Le, L.

1994-01-01

359

Enhanced electrochemical performance of unique morphological LiMnPO/C cathode material prepared by solvothermal method  

NASA Astrophysics Data System (ADS)

The LiMnPO 4/C composite material with ordered olivine structure was synthesized in 1:1(v/v) enthanol-water mixed solvent in the presence of cetyltrimethylammonium bromide (CTAB) at 240 ?C. Rod-like particle morphology of the resulting LiMnPO 4/C powder with a uniform particle dimension of 150 × 600 nm was observed by using scanning electron microscope and the amount of carbon coated on the particle surface was evaluated as 2.2wt% by thermogravimetric analysis, which is reported for the first time to date for LiMnPO 4/C composite. The measurement of the electrochemical performance of the material used in rechargeable lithium ion battery shows that the LiMnPO 4/C sample delivers an initial discharge capacity of 126.5 mA h g -1 at a constant current of 0.01 C, which is 74% of the theoretical value of 170 mA h g -1. The electrode shows good rated discharge capability and high electrochemical reversibility when compared with the reported results, which is verified further by the evaluation of the Li ion diffusion coefficient of 5.056×10 -14 cm 2/s in LiMnPO 4/C.

Wang, Yourong; Yang, Yifu; Yang, Yanbo; Shao, Huixia

2010-01-01

360

The compatibility of rhenium and osmium in natural olivine and their behaviour during mantle melting and basalt genesis  

NASA Astrophysics Data System (ADS)

Rhenium and osmium (Re-Os) elemental abundances have been obtained for magmatic olivine from a range of host basalt compositions, for mantle olivine and coexisting phases (silicate and sulphide) from a spinel-peridotite, and olivine and Fe-Ni metal from Pallasite meteorites. These data indicate that Re and Os concentrations in olivine are low in both mantle and magmatic environments, and both elements preferentially partition into silicate melt, sulphide or Fe-Ni metal, relative to olivine. For magmatic olivine the partition coefficients for Re and Os correlate with the MgO content of the olivine (like Fe, Mn and Ni), which suggests that the observed partitioning reflects substitution onto crystallographic sites, rather than defects or the presence of included phases. These data indicate that Os is extremely incompatible (that is, excluded from the silicate structure) in magmatic olivine, which suggests that olivine crystallisation alone cannot be responsible for the low Os contents of some oceanic basalts. Rather, olivine crystallisation is itself responsible for sulphide precipitation (in which Os is highly compatible), by producing sulphur saturation of the melt, and it is the coupled crystallisation of these phases that effects the Os-Mg-Ni co-variations observed in oceanic basalts. Rhenium is also incompatible in magmatic olivine but the data suggest that for Fe-rich olivine compositions Re may become compatible, which may explain, at least in part, the compatible behaviour of this element during basalt petrogenesis on other planetary bodies, such as Mars and the Moon. Preliminary data for mantle olivine, not demonstrably contaminated by included phases, suggest that the high Os concentrations (relative to magmatic olivine) relate to partitioning with a sulphide, rather than silicate melt.

Burton, Kevin W.; Gannoun, Abdelmouhcine; Birck, Jean-Louis; Allègre, Claude J.; Schiano, Pierre; Clocchiatti, Roberto; Alard, Olivier

2002-04-01

361

Trace element composition of olivine - implications for the evolution of the olivine gabbro-troctolite-hosted Voisey's Bay Ni-Cu-Co sulfide deposit, Labrador  

NASA Astrophysics Data System (ADS)

The Mesoproterozoic Voisey's Bay intrusion is part of the Nain Plutonic Suite, which transects the 1.85 Ga collisional boundary between the Proterozoic Churchill Province and the Archean Nain Province in Eastern Labrador. The intrusion comprises a group of troctolitic to olivine gabbroic bodies linked by olivine gabbro dikes; together these rocks host the world-class Voisey's Bay Ni-Cu-Co sulfide deposit. Zones of massive and disseminated sulfide mineralization (Reid Brook, Discovery Hill, Mini-Ovoid and Ovoid) occur within a dike and at the entry line of this dike into a larger intrusion termed the Eastern Deeps [1, 2, 3]. At least two pulses of magma have generated the intrusion and the associated sulfide mineralization; an initial surge that achieved sulfide saturation by interacting with upper crustal rocks, and a later pulse of fresh, undepleted magma that forced the initial magma upwards and both remobilized the immiscible sulfide liquid and upgraded it in metal content [1, 2, 3]. Previous research [1, 2] has shown that the Ni content of olivine from the distinct sulfide-bearing host rocks is highly variable, and also indicative of both magma mixing and interaction of silicate magmas with sulfide. To further validate the significance of the olivine chemistry as a tracer for ore-forming petrological processes, we have determined the abundances of Cr, Mn, Co, Ni, Zn in olivines from the various mafic lithologies of the Eastern Deeps intrusion using Secondary Ion Mass Spectrometry. We present systematic variations in Mn, Co, Ni and Zn with Fo-content in olivines for both sulfide-free and sulfide-bearing zones. Olivines from mineralized and brecciated troctolitic/gabbroic zones display significantly higher Mn (up to 11,000 ppm) and Zn (up to 550 ppm) concentrations than those from nominally barren counterparts. The barren troctolite, broadly termed normal troctolite (NT), is a petrographically homogenous plagioclase and olivine cumulate. However, olivine compositional data establish the presence of "reef-like" horizons with, for instance, elevated Ni concentrations (up to 2,500 ppm), versus surrounding horizons where values of ? 1,500 ppm are predominant. These horizons correspond with deflections in the whole-rock MgO, Fe2O3 and MnO contents. If these horizons are widespread and traceable laterally within the intrusion it would imply that: (1) a "cryptic-layering" might be preserved in olivines from the otherwise homogenous NT - indicating either crystallization from an input of fresh, undepleted mafic magma, or an interaction of those olivines with a Ni-rich sulfide liquid [1, 2], (2) the high Mn and Zn concentrations, coupled with lower forsterite values, are probably a result of crystallization from a country rock-contaminated mafic magma, and therefore, might act as a mineral-based indicator for the assimilation of upper crustal material. These observations may assist in developing a signature for olivines that have been in contact with highly contaminated (and thus potentially sulfide saturated) magmas. [1] Li et al. (2000) Econ. Geol. 95, 771-799. [2] Li and Naldrett (1999) Lithos 47, 1-31. [3] Lightfoot and Naldrett (1999) GAC Vol. 13, 1-30.

Bulle, F.; Layne, G. D.

2011-12-01

362

Compositional Variations of Olivines and Pyroxenes in Chondritic Interplanetary Dust Particles  

NASA Astrophysics Data System (ADS)

It is a fundamental goal of interplanetary dust particle (IDP) research to determine the sources and histories of these primitive extraterrestrial materials. Chondritic IDPs have been divided into anhydrous and hydrous varieties. The presumption is that hydrated IDPs experienced aqueous alteration on parent bodies (hydrous asteroids or possibly comets). We wish to discover whether the anhydrous IDPs were the initial raw materials for these reactions. We report here analyses of olivines and pyroxenes from 22 large (>15 micrometers) chondritic IDPs: 11 anhydrous and 11 hydrous. We find there exists no significant difference in the compositions of olivines from olivine vs. pyroxene dominated IDPs. The degree of heterogeneity of these olivine compositions from anhydrous IDPs (Fo44-100) is great, significantly exceeding that of the olivines from the hydrous IDPs (Fo76-100) we examined. We observe the same relationship for orthopyroxenes (En57-100 for anhydrous, En79-100 for hydrous). Interestingly, we encountered true diopsides predominantly in pyroxene-dominated hydrous IDPs. Some anhydrous IDPs also displayed restricted compositional ranges for olivines and pyroxenes. For sulfate- containing anhydrous IDPs, olivines and orthopyroxenes had the ranges Fo91-100 and En94-100; for melted (atmospherically ablated) IDPs these ranges were Fo90-100 and En91-94. Are hydrous and anhydrous IDPs genetically related? With the exception of some from the serpentine class (Bradley and Brownlee, 1991), all chondritic IDPs have nearly identical mineralogies (Zolensky and Lindstrom, 1992). The compositional ranges of olivines and pyroxenes in these materials are quite dissimilar, with those from hydrous IDPs being relatively magnesium-rich; however this could be explained by a relatively greater ease of destruction of iron-rich silicates during aqueous alteration. It is known that increasing the Fe^2+ content of olivine decreases the temperature at which serpentinization occurs (Deer et al., 1982). This is apparently due to greater dislocation densities for Fe-rich olivines, and oxidation of Fe^2+. If a similar phenomenon affects alteration of pyroxenes and olivines to smectite, then the genetic relation of hydrous to anhydrous IDPs is permitted by our results. We have already reported that the Mg-Fe compositional range exhibited by phyllosilicates in hydrated IDPs is nearly identical to that of olivines and pyroxenes in anhydrous IDPs (Zolensky and Lindstrom, 1992); this observation also permits a genetic link between these IDP types. However, it is also possible that hydrous are not genetically related to anhydrous IDPs. We note that the relatively Mg-rich compositions of olivines and orthopyroxenes in sulfate-containing IDPs can also be explained by preferential destruction of Fe-rich olivines by oxidation of Fe^2+. The ablated IDPs are merely showing the results of equilibration. Are chondritic IDPs merely small samples of the parent bodies of chondritic meteorites? Aside from differences in bulk composition and physical properties, IDPs differ from all chondritic meteorites except CIs and CMs in the compositional ranges of olivines and pyroxenes (for olivines: CV3- Fo40-60; CO3- Fo40-70; H3, L3 and LL3- Fo30-80; Scott et al., 1988; Dodd, 1981). Although a few hydrous IDPs (a subset of the serpentine class particles) are apparently related to CMs (Zolensky and Lindstrom, 1992), the majority are mineralogically dissimilar. Small carbonaceous clasts contained within certain meteorites (e.g., CR chondrites, the Bholghati howardite, LEW 85300 polymict eucrite and Kaidun carbonaceous breccia) have similar mineralogies to some IDPs (Zolensky et al., 1992), although more detailed analyses of these materials are still required. In summary, most chondritic IDPs are compositionally and mineralogically distinct from chondritic meteorites, but have apparently experienced similar conditions of origin and evolution both in the solar nebula and on parent bodies. References: Bradley and Brownlee (1991) Science 251, 549; Deer, Howie, and Zussman (1982)

Zolensky, M.; Barrett, R.

1992-07-01

363

Relation of the spectroscopic reflectance of olivine to mineral chemistry and some remote sensing implications  

NASA Technical Reports Server (NTRS)

High-resolution visible and near-IR diffuse spectral reflectance are used to systematically investigate apparent wavelength shifts as a function of mineral chemistry in the Fe/Mg olivine series from Fo(11) to Fo(91). The study also shows that trace amounts of nickel can be spectrally detected in the olivine structure. Significant compositional information can only be extracted at relatively high resolution, because the overall spectral characteristics of the olivines change only subtly as a function of the Fe/Mg ratio. This laboratory study is expected to aid in the interpretation of remotely sensed data from both terrestrial and extraterrestrial bodies. Terrestrial applications may include the recognition of ultramafic, ultrabasic, and basaltic terrains which in themselves may have mineral potential. Among extraterrestrial applications, the asteroids are obvious candidates for further examination. Some permutations of Fe-Mg-Ni relations in olivines are discussed as they apply to the interpretation of asteroid surfaces and other extraterrestrial bodies.

King, Trude V. V.; Ridley, W. Ian

1987-01-01

364

Trace Element Distribution Between Olivine and Kirschsteinite in Angra Dos Reis  

NASA Technical Reports Server (NTRS)

The angrites are a small and enigmatic group of basaltic achondrites that possess unique mineralogical and chemical properties. The dominant mineralogy of the seven angrite members (Angra dos Reis, LEW 86010, LEW 87051, Asuka 881371, Sahara 99555, D Orbigny, and a new Moroccan member) is fassaite, olivine, and plagioclase. Angrites display a wide range of thermal histories, with Angra dos Reis (AdoR) exhibiting a cooling history different from that of the rapidly cooled members and from LEW86010, a more slowly cooled member. AdoR could represent either a cumulate or a porphyritic igneous rock that was later altered by metamorphism. We are re-examining the thermal history of AdoR in light of the more recently described angrite members. Our emphasis is a trace element study of low-Ca olivine, which we refer to as olivine, and high-Ca olivine, which we refer to as kirschsteinite, in AdoR.

Fittipaldo, M. M.; Jones, R. H.; Shearer, C. K.

2003-01-01

365

Extracting Olivine (Fo-FA) Compositions from Raman Spectral Peak Positions.  

National Technical Information Service (NTIS)

Olivine and pyroxene are two major basaltic minerals that have been identified at Gusev Crater and Meridiani Planum by the Mars Exploration Rovers. Full petrologic characterization of a sample (rock or soil), however, requires determining the range of min...

K. Kuebler B. L. Jolliff A. Wang

2005-01-01

366

Palisades sill: Origin of the olivine zone by separate magmatic injection rather than gravity settling  

SciTech Connect

The still widely cited view of the Palisades sill, northeastern United States, being differentiated largely by vertically directed olivine-dominated frationation is not supported by available structural, petrographic, and geochemical data. Rather, the sill can be viewed as a sheetlike composite intrusion, possibly made up of multiple magma types common to the Mesozoic eastern North America magmatic province. The famous olivine zone of the Palisades sill may have resulted from a separate late intrusion of olivine-normative magma and not from gravity-controlled, olivine-accumulation processes. Pyroxene-dominated fractionation accounts for much of the vertical and lateral compositional variations in the Palisades sill and other related intrusions from the province.

Husch, J.M. (Rider College, Lawrenceville, NJ (USA))

1990-08-01

367

Cosmic-Ray Exposure Ages of Pallasites Derived from Metal and Olivine Separates  

NASA Astrophysics Data System (ADS)

Cosmic-ray exposure ages of pallasites based on cosmogenic noble gas and radionuclide measurements on metal and olivine separates cluster around 100 My, suggesting that they may have been ejected in a single event from the same parent body.

Huber, L.; Cosarinsky, M.; Cook, D.; Leya, I.; Herzog, G.

2011-03-01

368

Olivine-Orthopyroxene Equilibrium in Metal-rich Systems: Applications to Achondrites and Equilibrated Chondrites  

NASA Technical Reports Server (NTRS)

Olivine and orthopyroxene are major minerals in every type of stony meteorite. The majority of achondritic meteorites and silicate-bearing iron meteorites have experienced high temperatures. If these temperatures persisted for an extended period of time then the iron contents of olivine and orthopyroxene should be in equilibrium. In their study of ungrouped clasts and chondritic meteorites, suggested that the equilibrium compositions of olivine and orthopyroxene should fall on a mixing line between LL chondrites and aubrites. Here we show that this is not necessarily the case and that a range of FeO contents in olivine and orthopyroxene can be in equilibrium with each other. The key parameters that determine the equilibrium Fe content in these minerals are temperature, oxygen fugacity (fO2), and silica activity (aSiO2).

Lauretta, D. S.; Benedix, G. K.; McCoy, T. J.

2003-01-01

369

Shape-Casting Titanium in Olivine, Garnet, Chromite, and Zircon Rammed and Shell Molds.  

National Technical Information Service (NTIS)

In seeking substitutes for such critical metals as chromium, cobalt, and nickel, the Bureau of Mines investigated techniques for shape-casting titanium in rammed sand molds. Castings were made in olivine, garnet, chromite, and, for comparison, zircon. It ...

J. M. Burrus R. K. Koch

1980-01-01

370

Cobalt in Forsterite-Olivine Deposits of the Blue Ridge, North Carolina and Georgia.  

National Technical Information Service (NTIS)

Bureau of Mines mineral resource investigations mandated by Congress through the RARE II (Roadless Area Review and Evaluation) program during the early 1980's included evaluation of two forsterite-olivine deposits in the Blue Ridge physiographic province ...

M. L. Chatman

1986-01-01

371

X ray Microprobe Determination of Chromium Oxidation State in Olivine from Lunar Basalt and Kimberlitic Diamonds.  

National Technical Information Service (NTIS)

The synchrotron x-ray microprobe is being used to obtain oxidation state information on planetary materials with high spatial resolution. Initial results on chromium in olivine from various sources including laboratory experiments, lunar basalt, and kimbe...

S. R. Sutton S. Bajt M. L. Rivers J. V. Smith

1993-01-01

372

Experimental study of the effect of water on olivine-ringwoodite transformation rate  

NASA Astrophysics Data System (ADS)

The persistence of metastable olivine in subducting slabs as they pass through the mantle transition zone would impact subduction zone geodynamics by decreasing negative buoyancy of the slab and, therefore, subduction rates. In addition, its subsequent transformation has been proposed as the origin of deep-focus earthquakes originating in the transition zone. In light of this, many previous studies have been conducted to determine kinetic parameters for the olivine-wadsleyite and olivine-ringwoodite transformations using both (Mg,Fe)2SiO4 and analog compositions. The qualitative enhancement of transformation rates by H2O in this system has also been well established. More recently, experimental work has quantitatively confirmed this effect using olivine containing 750-4900 wt ppm H2O. However, several lines of evidence suggest the presence of lower water contents in the Earth's mantle. Presented here are results showing the effect of minor, yet geologically relevant, amounts of water on the olivine-ringwoodite transformation. Multi-anvil experiments are being conducted on 500-micron diameter San Carlos olivine spheroids. These spheroids are first deuterated in piston-cylinder experiments in which liquid D2O and San Carlos olivine, along with silica activity and oxygen fugacity buffers, are pressure sealed in a thick-walled silver capsule. D2O is used as a proxy for H2O, because the low deuterium background enables precise quantification by SIMS. The separate deuteration procedure provides for greater control over deuterium content than in previous experiments and allows for pre-transformation characterization of the olivine. The olivine used in this study contains approximately 300 wt ppm D2O. Transformation experiments have been conducted at 18 GPa and 1100, 900, 800 and 700oC. At 900oC, the ringwoodite growth rates are over an order of magnitude faster than experimentally derived rates for dry olivine. In addition, transformation is observed at 700oC on an experimental time scale, 200oC lower than in the dry system. Ringwoodite growth rates in the wet system appear to be less time dependant, possibly due to weakening of the ringwoodite by D2O, thereby reducing the build-up of elastic strain. These results strongly suggest that the persistence of metastable olivine in subduction zones will be greatly decreased by the presence of even modest amounts of water.

Diedrich, T.; Sharp, T. R.; Leinenweber, K.

2005-12-01

373

Origin of high-FO Olivine-Phyric Volcanic Rocks: a Melt Iinclusions Perspective  

NASA Astrophysics Data System (ADS)

Common features of high-Fo olivine-phyric volcanics include (1) large, essentially unzoned cores of olivine phenocrysts; (2) a wide range (up to 15 Fo units) of phenocryst core compositions within a sample; (3) lack of correlation between the maximum Fo and rock MgO content within a cogenetic series; and (4) evolved compositions of groundmass which are often more evolved than what is expected to be in equilibrium with the least magnesian olivine phenocrysts. Cooling of olivine phenocrysts in the magmatic system prior to eruption results in post-entrapment diffusive reequilibration of their melt inclusions. Analysis of this process reveals that it is rarely completed, suggesting generally short residence times (< 6 months) and fast cooling rates (> 1-2 o/day) of high-Fo phenocrysts, with diffusion distances of < 100 microns. This implies that the unzoned cores of high-Fo olivines cannot reflect diffusive reequilibration of originally zoned phenocrysts, as often assumed, but instead they are the result of fast efficient separation of olivines from the crystallising magma. Thus, the main source of high-Fo crystals in erupted magmas is the cumulate zone, ie, olivine-phyric rocks represent mixtures of an evolved transporting magma (forming the groundmass of the rock) with crystals that were formed during crystallisation of more primitive melt(s). Such a mixed magma is formed during the eruption event, but this is only possible when eruption occurs within 6 months after a new batch of primitive magma enters the magmatic system. High-Fo olivines can reside in magma chambers for longer times, however these olivines are unlikely to be erupted as phenocrysts, being efficiently cemented in the cumulate piles. The evolved magma may reside in the chambers for a long time. This reconciles long magma residence times estimated from the compositions of rocks with short residence times of high-Fo olivine phenocrysts. The mixed origin of high-Fo olivine-phyric rocks also explains coexistence of variably re-equilibrated melt inclusions of similar sizes in different grains in a single sample. This suggests that individual phenocrysts experienced different cooling rates and must have come from different parts of the magmatic system. A plumbing system model developed by B. Marsh can explain all observations well. It involves magma passing through a sequence of interconnected sills or chambers with well-developed mush columns. These columns consist of a variety of local crystallisation environments characterised by contrasting cooling rates. During an eruption, magma rising through such a column can inherit crystals from different pockets, and melt inclusions within these accumulated phenocrysts may be variably re-equilibrated.

Danyushevsky, L. V.

2003-04-01

374

Effect of Mineral Reaction on the Deformation of Plagioclase-Olivine Aggregates  

NASA Astrophysics Data System (ADS)

There have been many studies that have described the relative timing of deformation and metamorphism in natural rocks, but there are few studies that have analysed the interrelationship of the processes that produce simultaneous deformation and chemical reactions. We studied the physical and microstructural relationships between the processes of deformation and chemical reaction by performing simple shear deformation experiments on plagioclase-olivine aggregates. Our study shows that deformation and reaction processes are strongly related by a mutual positive feedback, and point out possible mechanisms for shear localization in the upper mantle lithosphere during subduction and extension. Shear deformation experiments were carried out on dry plagioclase-olivine mixtures (4-10 ? m grain sizes, +/-50-50 vol.% olivine-plagioclase ratio) in a Griggs apparatus under a constant applied shear strain rate of ˜5*10-5s-1 at 900° C and 1.0-1.6 GPa confining pressures. We have studied the plagioclase-olivine deformation in presence and absence of reaction by choosing plagioclase to be of labradorite (An60) and anorthite (An92) composition. At 1.0-1.6 GPa confining pressures, the anorthite-olivine samples react to spinel-pyroxene bearing assemblages, whereas the labradorite-olivine samples do not. Labradorite and anorthite are expected to have fairly similar deformation behaviour. Effect of reaction on deformation: In the absence of reaction, labradorite-olivine mixtures are so strong at the chosen experimental conditions that they hardly deform plastically. In contrast, anorthite-olivine mixtures deformed at the same temperature and strain rate react during deformation, producing a stress maximum ( ˜375 MPa) followed by a significant stress decrease. Regardless of the chosen confining pressure, reacting samples commonly weaken towards a shear stress of ˜275 MPa. The plagioclase-olivine reaction strongly reduces the grain size of the samples (down to 0.1 ? m), and causes a transition from grain size insensitive (dislocation) creep of plagioclase and olivine to diffusion accommodated grain boundary sliding of the reaction products, even though the newly formed minerals (e.g. pyroxene, spinel) are mechanically stronger than the original minerals. Effect of deformation on reaction: The plagioclase-olivine reaction progress is greatly enhanced by differential stress and/or crystal plastic strain. At 1.5 GPa, hydrostatic experiments of 168 hours show less than 30% reaction progress, whereas in the deformation experiments ( ˜58 hours) the reaction goes to completion.

de Ronde, A.; Stünitz, H.; Tullis, J.

2003-12-01

375

Origin of Water on Earth: Hydroxyl and Hydrogen in MgO and Olivine  

Microsoft Academic Search

One fundamental question is the origin of water on Earth. Water could have been delivered from space by comets, or outgassed from the Earth's mantle. To address this issue, we need to know how much H2O is dissolved in olivine, the predominant upper mantle mineral. Olivine and MgO are nominally anhydrous. When crystallizing in an H2O-laden environment, they dissolve water

M. Freund; R. Knobel; J. T. Dickinson; F. T. Freund

2002-01-01

376

Formation of ferriolivine and magnesioferrite from Mg — Fe-olivine: Reactions and kinetics of oxidation  

Microsoft Academic Search

Olivine samples (Fa 11) have been oxidized in air (fO2 = 0.2 atm) at temperatures ranging from 350–700 °C and examined by Mössbauer spectroscopy, transmission electron microscopy, X-ray powder diffraction and thermomagnetic analysis. Oxidation of olivine was found to result in ferriolivine, magnesioferrite (major oxide phase) and magnetite (minor oxide phase) formation. Ferriolivine forms planar (001) precipitates, 0.6 nm in

N. R. Khisina; D. A. Khramov; M. V. Kolosov; A. A. Kleschev; Lawrence A. Taylor

1995-01-01

377

A Tale of Two Olivines: Magma Ascent in the Auckland Volcanic Field, New Zealand  

NASA Astrophysics Data System (ADS)

The Auckland Volcanic Field (AVF) is a nephelinitic to subalkali basaltic monogenetic field centered on the city of Auckland, New Zealand. Lavas are olivine-phyric, and the deposits of several volcanoes in the field contain olivine crystals with chrome spinel (Cr-spinel) inclusions. Microprobe analyses show at least two populations of olivine, categorised by their Mg# and their spinel inclusion compositions: the first has olivines that are euhedral, have compositions slightly less forsteritic than expected for whole rock Mg#, and have Cr-spinel inclusions with relatively low Cr2O3 contents of ~20%. These are interpreted as antecrysts inherited from the mantle source that yielded their host magma. The second population is characterised by olivines that are sub- to euhedral, are significantly more forsteritic than expected from their host whole rock Mg#, and have Cr-spinel inclusons with relatively high Cr2O3 contents of ~50%. These are interpreted as xenocrysts. The composition of these high Cr2O3 spinels very closely resembles the composition of spinels within olivines in dunite sampled from the Dun Mountain Ophiolite on the South Island of New Zealand. The northward extension of the Dun Mountain complex beneath the North Island is defined by the Junction Magnetic Anomaly, marking a crustal terrane boundary that underlies the Auckland Volcanic Field. These data indicate that the magmas that have risen to produce the volcanoes of the Auckland Volcanic Field have carried crystals from an underlying ultramafic crust as well as from their asthenospheric source. Euhedral olivine crystals which do not contain Cr-spinel are also present in AVF lavas and these are interpreted as true phenocrysts that crystallised directly from their host magmas. The lack of reaction textures at crystal margins suggests rapid ascent rates. A crustal origin for the xenocrysts not only has large implications for ascent rate modelling of olivines, but also for the crustal structure of the Auckland area and possible magma ascent paths under the AVF.

Smid, E. R.; McGee, L. E.; Smith, I. E.; Lindsay, J. M.

2013-12-01

378

Using Fe and Mg in Olivine as an Indicator of Asteroidal Hydrothermal Alteration  

Microsoft Academic Search

Amoeboid Olivine Aggregates (AOAs) found in CO3 meteorites are sensitive indicators of parent body alteration. Because chondritic meteorites are considered to be some of the most primordial material of the early solar system, studying these features reveals information about the hydrothermal alteration undergone after the time of their formation. As water encounters the AOAs, the Mg-rich olivine, forsterite (Mg2SiO4), is

Anne Sweet; Lysa Chizmadia

2007-01-01

379

Surface characterization of acid-leached olivines by X-ray photoelectron spectroscopy  

Microsoft Academic Search

X-ray photoelectron spectroscopy was used to study the surface alteration of olivines (fayalite and forsterite) during acid dissolution (0.05 mol 1?1 H2SO4 at room temperature for one day). The abundances of Fe and Mg, relative to Si, in the near surface of olivines decreased after acid dissolution. The divalent cations in the fayalite were removed more readily than those in

Haruhiko Seyama; Mitsuyuki Soma; Atsushi Tanaka

1996-01-01

380

Superparamagnetic clusters of Fe\\/2+\\/spins in lunar olivine - Dissolution by high-temperature annealing  

Microsoft Academic Search

The results of a low-temperature Moessbauer study of superparamagnetic clustering of Fe(2+) spins in lunar olivines are presented. Such clusters are present in approximately 60% of all high-olivine lunar samples studied to date. It is shown that the clusters can be totally or partially dissolved by high-temperature above 970 C annealing followed by rapid cooling. A simple qualitative model of

G. P. Huffman; G. R. Dunmyre

1975-01-01

381

Clast-laden nature and the origin of Luna 24 olivine-vitrophyres  

NASA Technical Reports Server (NTRS)

The study shows that Luna 24 olivine-vitrophyric particles are actually fragments of clast-laden melt and are not from a very low titanium (VLT) mare basalt flow. Diversity of composition and clast population, and morphological similarity to ropy glasses suggest an impact melt origin. Compositionally, the olivine-vitrophyres resemble the high magnesian VLT basalts, which may have been the target and source of the impact melt.

Basu, A.; Mckay, D. S.; Fruland, R. M.

1978-01-01

382

The isotopic composition of magnesium in mantle olivine: Records of depletion and metasomatism  

Microsoft Academic Search

We have investigated detailed Mg isotopic variations in the lithospheric mantle by analysing olivine in mantle-derived peridotite xenoliths and megacrysts. High-precision in situ analyses of 26Mg\\/24Mg and 25Mg\\/24Mg are made using a laser-ablation microprobe and MC-ICPMS. Measurements are done using a standard-sample bracketing technique with an in-house olivine standard. Replicate analyses of this standard give a precision of 0.20‰ (2sd)

N. J. Pearson; W. L. Griffin; O. Alard; Suzanne Y. O'Reilly

2006-01-01

383

Predicting the neutralisation of acid mine drainage in anoxic olivine drains  

Microsoft Academic Search

The precipitation of gypsum within anoxic limestone drains subjected to very acidic and sulphate rich acid mine drainage is a problem that can be prevented by initial neutralisation of the drainage using magnesium-rich olivine. The applicability of this concept is limited to the low pH region (i.e. pH<3) where gypsum precipitation is a potential problem and the olivine dissolution rate

R. A. Kleiv; M. Thornhill

2008-01-01

384

Effect of metamorphism on isolated olivine grains in CO3 chondrites  

NASA Technical Reports Server (NTRS)

The presence of a metamorphic sequence in the CO3 chondrite group has been shown previously to result in changes in properties of chondrule silicates. However, the role of isolated olivine grains during metamorphism of these chondrites has not been addressed. Isolated olivine grains in two metamorphosed CO3 chondrites, Lance and Isna, have been investigated in this study in order to assess the compositional properties of isolated olivine grains that may be attributable to metamorphism. Compositional changes in isolated olivines with increasing petrologic subtype are very similar to changes in chondrule olivines in the same chondrites. Olivine compositions from all occurrences (chondrules, isolated grains, and matrix) converge with increasing petrologic subtype. The degree of equilibration of minor elements is qualitatively related to the diffusion rate of each element in olivine, suggesting that diffusion-controlled processes are the most important processes responsible for compositional changes within the metamorphic sequence. The data are consistent with metamorphism taking place in a closed system on the CO3 chondrite parent body. Fe-poor olivine grains in metamorphosed chondrites are characterized by an Fe-rich rim, which is the result of diffusion of Fe into the grains from Fe-rich matrix. In some instances, 'complex', Fe-rich rims have been identified, which appear to have originated as igneous overgrowths and subsequently to have been overprinted by diffusion processes during metamorphism. Processes experienced by CO3 chondrites are more similar to those experienced by the ordinary chondrites than to those encountered by other carbonaceous chondrites, such as the CV3 group.

Jones, Rhian H.

1993-01-01

385

Effects of water on dynamically recrystallized grain-size of olivine  

Microsoft Academic Search

Recrystallized grain-size versus stress relationship for olivine has been determined under water-poor and water-rich conditions. We found that when the water content in olivine exceeds ?800ppm H\\/Si, the size of recrystallized grains is about two to three times larger than under water-poor conditions, compared at the same stress level. Microstructural observations of deformed samples show that the ratio of recrystallized

Haemyeong Jung; Shun-Ichiro Karato

2001-01-01

386

Water in Pyroxene and Olivine from Martian Meteorites  

NASA Technical Reports Server (NTRS)

Water in the interior of terrestrial planets can be dissolved in fluids or melts and hydrous phases, but can also be locked as protons attached to structural oxygen in lattice defects in nominally anhydrous minerals (NAM) like olivine, pyroxene, or feldspar [1-3]. Although these minerals contain only tens to hundreds of ppm H2O, this water can amount to at least one ocean in mass when added at planetary scales because of the modal dominance of NAM in the mantle and crust [4]. Moreover these trace amounts of water can have drastic effects on melting temperature, rheology, electrical and heat conductivity, and seismic wave attenuation [5]. There is presently a debate on how much water is present in the martian mantle. Secondary ionization mass spectrometry (SIMS) studies of NAM [6], amphiboles and glass in melt inclusions [7-10], and apatites [11, 12] from Martian meteorites report finding as much water as in the same phases from Earth's igneous rocks. Most martian hydrous minerals, however, generally have the relevant sites filled with Cl and F instead of H [13, 14], and experiments using Cl [15] in parent melts can reproduce Martian basalt compositions as well as those with water [16]. We are in the process of analyzing Martian meteorite minerals by Fourier transform infrared spectrometry (FTIR) in order to constrain the role of water in this planet s formation and magmatic evolution

Peslier, A. H.

2012-01-01

387

Charge Localization and Transport in Lithiated Olivine Phosphate Materials  

SciTech Connect

We report density functional theory (DFT) calculations for olivine-type LiTMPO4 and TMPO4 (TM=Mn, Fe, Co, Ni) structures, using GGA+U and the B3LYP hybrid density functional that includes nonlocal Fock exchange. TM is typically characterized in terms of the formal oxide states of 2+ or 3+, corresponding to TM with localized charge in LiTMPO4 and TMPO4 structures, respectively, in which electron transport would take place by thermally activated hopping of electrons strongly localized on the transition metal (small polarons). In this work, we assess the validity of the concept of formal TM oxidation states in these materials, and conclude that the valence depends in large part on the strength of d-p hybridization. Stable small polaron formation, i.e., mixed 2+ and 3+ valence states, appears to require that the ratio of differences in the metal and oxygen ionic charges (dQTM/dQO) of the two end member phases is larger than 2, corresponding to the mixed-valence TM system. If the ratio of dQTM/dQO is smaller than 2, excess electrons prefer delocalization and the system behaves more single-valence like with charge transport more akin to metallic conduction. The critical ratio emerging from our analysis may turn out to be relevant to other transition metal systems as well, as a criterion to discriminate single-valence or mixed-valence characteristics and hence the predominant conduction mechanism.

Yu, Jianguo; Rosso, Kevin M.; Liu, Jun

2011-11-10

388

Excitation and relaxation of olivine after swift heavy ion impact  

NASA Astrophysics Data System (ADS)

A multiscale model was developed to describe excitation and initial relaxation of an insulator after an impact of a swift heavy ion (SHI) decelerated in the electronic stopping regime. This model consists of a combination of three methods: (a) Monte Carlo simulations of the nonequilibrium kinetics of the electron subsystem of a solid at the femtosecond scale after the projectile passage. The complex dielectric function (CDF) is used to construct the cross sections for the MC model taking into account a collective response of the electron ensemble to excitation. (b) A molecular-kinetic approach describing further spatial spreading of electrons after finishing of ionization cascades up to hundred femtoseconds. And (c) molecular dynamics simulations of a reaction of the lattice on the excess energy transferred from the relaxing electron subsystem at the picosecond time scale. The dynamic structure factor (DSF) formalism is used to calculate the electron-lattice energy exchange in a general way which is valid for sub-picosecond timescales, beyond the phononic approximation of the lattice dynamics. The calculations were performed for 2 GeV Au ion in olivine, demonstrating a heating of the lattice up to 700 K in the nanometric scale picoseconds after the projectile passage.

Gorbunov, S. A.; Medvedev, N. A.; Rymzhanov, R. A.; Terekhin, P. N.; Volkov, A. E.

2014-05-01

389

Angrite LEW87051: Are the olivines pheno's or xeno's? A continuing story  

NASA Technical Reports Server (NTRS)

The achondrite LEW87051 is a porphyritic basalt consisting of large subhedral to euhedral zoned olivines in a finer-grained groundmass. The texture of this groundmass looks remarkably like a quenched melt. However, although the rock is clearly igneous, its exact origins and history are under dispute. From petrographic observations, Prinz felt that the large olivines were xenocrysts and that the zoning reflected interaction with an unrelated, CAI-enriched melt. McKay et al. was able to model the olivines as phenocrysts, whose zoning was the result of a parent melt that changed in composition as material crystallized, e.g., fractional crystallization in a closed system, and calculated a parent melt composition. Jurewicz and McKay compared the calculated parent melt composition with actual partial melts from CV and CM chondrites. They showed that the calculated melt was substantially different from equilibrium melts of these chondrites; however, the LEW87051 groundmass composition was similar to some of the low temperature partial melts, although slightly enriched in AN (or depleted in OL) components. This study presents the results of an independent petrologic look at other olivines in LEW87051 and the preliminary results of a quantitative model for the major zoning in these olivines as diffusive-exchange with an olivine-saturated, low temperature angritic melt.

Jurewicz, A. J. G.; Mckay, G. A.

1993-01-01

390

A comparison of FeO-rich, porphyritic olivine chondrules in unequilibrated chondrites and experimental analogues  

NASA Astrophysics Data System (ADS)

Experimentally produced analogues of porphyritic olivine (PO) chondrules in ordinary chondrites provide an important insight into chondrule formation processes. We have studied experimental samples with PO textures grown at three different cooling rates (2, 5 and 100 C/h), and samples that have been annealed at high temperatures (1000-1200 C) subsequent to cooling. These are compared with natural chondrules of similar composition and texture from the ordinary chondrites Semarkona (LL3.0) and ALH 81251 (LL3.3). Zoning properties of olivine grains indicate that the Semarkona chondrules cooled at comparable rates to the experiments. Zoning in olivine from chondrules in ALH 81251 is not consistent with cooling alone but indicates that the chondrules underwent an annealing process. Chromium loss from olivine is very rapid during annealing and calculated diffusion coefficients for Cr in olivine are very similar to those of Fe-Mg interdiffusion coefficients under the same conditions. Annealed experimental samples contain an aluminous, low-Ca pyroxene which forms by reaction of olivine and liquid. No similar reaction texture is observed in ALH 81251 chondrules, and this may be evidence that annealing of the natural samples took place at considerably lower temperatures than the experimental analogues. The study supports the model of chondrule formation in a cool nebula and metamorphism of partly equilibrated chondrites during reheating episodes on the chondrite parent bodies.

Jones, R. H.; Lofgren, G. E.

1993-06-01

391

Characterization and Petrologic Interpretation of Olivine-Rich Basalts at Gusev Crater, Mars  

NASA Technical Reports Server (NTRS)

Rocks on the floor of Gusev crater are basalts of uniform composition and mineralogy. Olivine, the only mineral to have been identified or inferred from data by all instruments on the Spirit rover, is especially abundant in these rocks. These picritic basalts are similar in many respects to certain Martian meteorites (olivine-phyric shergottites). The olivine megacrysts in both have intermediate compositions, with modal abundances ranging up to 20-30%. Associated minerals in both include low-calcium and high-calcium pyroxenes, plagioclase of intermediate composition, iron-titanium-chromium oxides, and phosphate. These rocks also share minor element trends, reflected in their nickel-magnesium and chromium-magnesium ratios. Gusev basalts and shergottites appear to have formed from primitive magmas produced by melting an undepleted mantle at depth and erupted without significant fractionation. However, apparent differences between Gusev rocks and shergottites in their ages, plagioclase abundances, and volatile contents preclude direct correlation. Orbital determinations of global olivine distribution and compositions by thermal emission spectroscopy suggest that olivine-rich rocks may be widespread. Because weathering under acidic conditions preferentially attacks olivine and disguises such rocks beneath alteration rinds, picritic basalts formed from primitive magmas may even be a common component of the Martian crust formed during ancient and recent times.

McSween, H. Y.; Wyatt, M. B.; Gellert, R.; Bell, J. F., III; Morris, R. V.; Herkenhoff, K. E.; Crumpler, L. S.; Milam, K. A.; Stockstill, K. R.; Tornabene, L. L.; Arvidson, R. E.; Bartlett, P.; Blaney, D.; Cabrol, N. A.; Christensen, P. R.; Clark, B. C.; Crisp, A.; DesMarais, D. J.; Economou, T.; Farmer, J. D.; Farrand, W.; Ghosh, A.; Golombek, M.; Gorevan, S.; Greeley, R.

2006-01-01

392

A comparison of FeO-rich, porphyritic olivine chondrules in unequilibrated chondrites and experimental analogues  

NASA Technical Reports Server (NTRS)

Experimentally produced analogues of porphyritic olivine (PO) chondrules in ordinary chondrites provide an important insight into chondrule formation processes. We have studied experimental samples with PO textures grown at three different cooling rates (2, 5 and 100 C/h), and samples that have been annealed at high temperatures (1000-1200 C) subsequent to cooling. These are compared with natural chondrules of similar composition and texture from the ordinary chondrites Semarkona (LL3.0) and ALH 81251 (LL3.3). Zoning properties of olivine grains indicate that the Semarkona chondrules cooled at comparable rates to the experiments. Zoning in olivine from chondrules in ALH 81251 is not consistent with cooling alone but indicates that the chondrules underwent an annealing process. Chromium loss from olivine is very rapid during annealing and calculated diffusion coefficients for Cr in olivine are very similar to those of Fe-Mg interdiffusion coefficients under the same conditions. Annealed experimental samples contain an aluminous, low-Ca pyroxene which forms by reaction of olivine and liquid. No similar reaction texture is observed in ALH 81251 chondrules, and this may be evidence that annealing of the natural samples took place at considerably lower temperatures than the experimental analogues. The study supports the model of chondrule formation in a cool nebula and metamorphism of partly equilibrated chondrites during reheating episodes on the chondrite parent bodies.

Jones, Rhian H.; Lofgren, Gary E.

1993-01-01

393

Olivine-rich rims surrounding chondrules in the Mokoia CV3 carbonaceous chondrite: Further evidence for parent-body processes  

NASA Astrophysics Data System (ADS)

Fine-grained rims surrounding chondrules and inclusions in the Mokoia CV3 carbonaceous chondrite can be divided into phyllosilicate-rich and olivine-rich types. We present a petrographic and electron microscopic study of the olivine-rich rims and their host objects (referred to as chondrules/olivine-rich rims). The olivine-rich rims consist mainly of Fe-rich olivine and very minor phyllosilicate (saponite). Their host chondrules contain minor saponite and phlogopite, which resulted from aqueous alteration of anhydrous silicates. Mineralogical and compositional characteristics of the chondrules/olivine-rich rims suggest that they experienced mild thermal metamorphic effects. The rims commonly contain veins of coarse-grained Fe-rich olivine, magnetite, and Fe-(Ni) sulfides. The chondrules show abundant evidence of alteration along their peripheries, and the alteration textures suggest a mechanism for rim formation by replacement of the chondrules. Initially, enstatite and opaque nodules preferentially reacted to form coarse, platy, Fe-rich olivine crystals, which were subsequently divided into finer grains. Forsterite was also replaced by Fe-rich olivine. As the alteration advanced, these Fe-rich olivines were disaggregated, mixed with simultaneously produced saponite, and formed rims. In contrast, the surrounding matrix shows no evidence of such alteration and metamorphism. These observations indicate that the chondrules/olivine-rich rims did not experience these secondary processes in their present setting. The results suggest that the chondrules/olivine-rich rims experienced extensive replacement reactions in an environment in which aqueous fluids existed but only in minor amounts. They have probably also undergone simultaneous and/or subsequent mild thermal metamorphism. We suggest that the chondrules/olivine-rich rims are actually clasts transported from a relatively dry region in the parent body that was different from the region where Mokoia was finally lithified.

Tomeoka, Kazushige; Ohnishi, Ichiro

2014-07-01

394

CO2-induced small water solubility in olivine and implications for properties of the shallow mantle  

NASA Astrophysics Data System (ADS)

H2O and CO2 are important components of fluids in the mantle at ?30-150 km depth, and may affect strongly water dissolution in nominally anhydrous olivine; however, available experimental hydrogenation of olivine has been nearly exclusively carried out in coexistence with H2O (CO2-free). In this study, the effect of CO2 on water solubility in olivine has been investigated by H-annealing natural olivine under peridotite- and fluid-saturated conditions. Experiments were conducted at 1.5-5 GPa and 1100-1300 °C, with oxygen fugacity controlled by Ni-NiO and with either H2O or H2O-CO2 as buffering fluid. The olivine shows no change in composition during the experiments. The infrared spectra of the hydrated olivine are characterized by prominent OH bands from ?3650 to 3000 cm in all the runs, at both high frequency (>3450 cm) and low frequency (<3450 cm), and the H2O solubility is ?120-370 ppm for the olivine in coexisting with H2O, and ?65-180 ppm for the olivine in coexisting with H2O-CO2. When CO2 is present in the buffering fluid, the H2O solubility of olivine is reduced by a factor of ?2, due to effect on the partitioning of water between minerals and coexisting fluid, and the measured H2O solubility shows independence on fluid composition (the molar ratio of CO2 to CO2 + H2O at ?0.2-0.5) given pressure, temperature and oxygen fugacity. Olivine equilibrated in the shallow mantle is probably dominated by OH groups in the wavenumber ?3650-3000 cm, and the intensity of OH bands at low frequency may be higher than or comparable to those at higher frequencies. The storage capacity of water in the shallow mantle in previous estimates may have been overestimated by a factor of at least ?4 if the observed effect of CO2 on water solubility is correct. Our results have profound influence on understanding partial melting, electrical conductivity anomalies and metasomatism in the shallow mantle.

Yang, Xiaozhi; Liu, Dingding; Xia, Qunke

2014-10-01

395

Titanium solubility in olivine in the system TiO2–MgO–SiO2: no evidence for an ultra-deep origin of Ti-bearing olivine  

Microsoft Academic Search

The finding of ilmenite rods in olivine from orogenic peridotites has sparked a discussion about the processes of incorporation and exsolution of titanium in olivine. We have experimentally investigated the solu- bility of Ti in olivine as a function of composition, temperature and pressure in the synthetic TiO2-MgO- SiO2 system. Experiments at atmospheric pressure in the temperature range 1,200-1,500? C

J. Hermann; H. S. C. O’Neill; A. J. Berry

2005-01-01

396

Abiotic Versus Biotic Weathering Of Olivine As Possible Biosignatures  

NASA Technical Reports Server (NTRS)

We are investigating the weathering of silicate minerals by both purely inorganic, and biologically mediated processes using field-emission scanning electron microscopy (FESEM) and energy dispersive x-ray spectroscopy (EDS). By resolving surface textures and chemical compositions of weathered surfaces at the sub-micron scale we hope to be able to distinguish abiotic from biotic weathering processes and so establish a new biosignature applicable to the study of astromaterials including but not limited to the Martian meteorites. Sterilized olivine grains (San Carlos, Arizona) no more than 1-2 mm in their longest dimension were optically assayed to be uniform in color and free of inclusions were selected as weathering subjects. Prior to all experiments surface morphologies and Fe/Mg ratios were determined for each grain using FE-SEM and EDS. Experiments were divided into two categories abiotic and biotic and were compared with "naturally" weathered samples. For the preliminary experiments, two trials (open and closed to the ambient laboratory environment) were performed under abiotic conditions, and three trials under biotic conditions (control, day 1 and day 2). The open system abiotic trials used sterile grains heated at 98 C and 200 C for both 24 and 48 hours in 1L double distilled de-ionized water. The closed system abiotic trials were conducted under the same conditions but in a sealed two layer steel/Teflon "bomb" apparatus. The biotic trials used sterile grains mounted in a flow-through device attached to a wellhead on the Columbia River aquifer. Several discolored, altered, grains were selected to document "natural" weathering surface textures for comparison with the experimental samples. Preliminary results indicate there are qualitative differences in weathered surface textures among all the designed experiments. The olivine grains in abiotic trials displayed etching, pitting, denticulate margins, dissolution and clay formation. The scale of the features ranged from tens to a few microns with textures that remained relatively sharp and were crystallographically controlled. These results were comparable to that observed in the "naturally" weathered comparison/reference grains. Chemical analysis by EDS indicates these textures correlated with the relative loss of Mg and Fe cations by diffusional processes. In contrast the biotic results indicated changes in the etching patterns on the scale of hundreds of nm, which are neither sharp nor crystallographically controlled (nanoetching). Organisms, organic debris and/or extracellular polymeric substances (biofilm) were often in close proximity or direct contact with the nanoetching. While there are many poorly constrained variables in natural weathering experiments to contend with, such as the time scale, the chemistry of the fluids and degree of biologic participation, some preliminary observations can be made: (1) certain distinct surface textures appear correlated with the specific processes giving rise to these textures; (2) the process of diffusing cations can produce many similar styles of surface textural changes; and (3) the main difference between abiotic and biotically produced weathering is the scale (microns versus nanometers) and the style (crystallographically versus noncrystallographically controlled) of the textural features. Further investigation into nanosize scale surface textures should attempt to quantify both textures and chemical changes of the role of microorganisms in the weathering of silicates. Additional experiments addressing nanoscale textures of shock features for comparison with the current data set.

Longazo, Teresa G.; Wentworth, Susan J.; Clemett, Simon J.; Southam, Gordon; McKay, David S.

2001-01-01

397

Diffusive Fractionation of Lithium Isotopes in Olivine Grain Boundaries  

NASA Astrophysics Data System (ADS)

Diffusive fractionation of isotopes has been documented in silicate melts, aqueous fluids, and single crystals. In polycrystalline rocks, the meeting place of two grains, or grain boundaries, may also be a site of diffusive fractionation of isotopes. We have undertaken an experimental and modeling approach to investigate diffusive fractionation of lithium (Li) isotopes by grain boundary diffusion. The experimental procedure consists of packing a Ni metal capsule with predominantly ground San Carlos olivine and subjecting the capsule to 1100C and 1GPa for two days in a piston cylinder apparatus to create a nominally dry, 'dunite rock'. After this synthesis step, the capsule is sectioned and polished. One of the polished faces of the 'dunite rock' is then juxtaposed to a source material of spodumene and this diffusion couple is subject to the same experimental conditions as the synthesis step. Li abundances and isotopic profiles (ratios of count rates) were analyzed using LA-ICP-MS. Li concentrations linearly decrease away from the source from 550ppm to the average concentration of the starting olivine (2.5ppm). As a function of distance from the source, the 7Li/6Li ratio decreases to a minimum before increasing to the background ratio of the 'dunite rock'. The 7Li/6Li ratio minimum coincides with the lowest Li concentrations above average 'dunite rock' abundances. The initial decrease in the 7Li/6Li ratio is similar to that seen in other studies of diffusive fractionation of isotopes and is thought to be caused by the higher diffusivity (D) of the lighter isotope relative to the heavier isotope. The relationship between D and mass (m) is given by (D1/D2) =(m2/m1)^?, where ? is an empirical fractionation factor; 1 and 2 denote the lighter and heavier isotope, respectively. A fit to the Li isotopic data reveals an effective DLi of ~1.2x10^-12 m/s^2 and a ? of 0.1. Numerical modelling was utilized to elucidate the relationship between diffusive fractionation produced in the grain boundaries versus the lattices of the individual grains of the 'dunite rock'. The model assumes a linear grain boundary juxtaposed to the long side of a rectangular crystal lattice. During a simulation, the diffusant may directly enter the lattice or the grain boundary. Once in the grain boundary, the diffusant may then continue to diffuse away from the source until the end of the simulation or, alternatively, it may be incorporated into the lattice at some point during its travels down the grain boundary. The model system is similar to that considered by Whipple-LeClaire (1963) and our model results agree well with their analytical solution. Preliminary modeling results show that the distinctive minimum in the isotopic ratio is only produced when diffusive fractionation occurs in the grain boundary and not when the fractionation occurs only in the lattice. This suggests that the isotopic profile observed in the experiments may be a product of diffusive fractionation in grain boundaries. Implications of these results extend to the longevity of Li isotopic heterogeneities in the mantle, and suggest that the isotopes of other elements, which have a large relative mass difference, may also be diffusively fractionated by grain boundary diffusion.

Homolova, V.; Watson, E. B.

2012-12-01

398

Temperature Dependence and Recoil-free Fraction Effects in Olivines Across the Mg-Fe Solid Solution  

NASA Technical Reports Server (NTRS)

Olivine and pyroxene are the major ferromagnesian minerals in most meteorite types and in mafic igneous rocks that are dominant at the surface of the Earth. It is probable that they are the major mineralogical components at the surface of any planetary body that has undergone differentiation processes. In situ mineralogical studies of the rocks and soils on Mars suggest that olivine is a widespread mineral on that planet s surface (particularly at the Gusev site) and that it has been relatively unaffected by alteration. Thus an understanding of the characteristics of Mossbauer spectra of olivine is of great importance in interpreting MER results. However, variable temperature Mossbauer spectra of olivine, which are needed to quantify recoil-free fraction effects and to understand the temperature dependence of olivine spectra, are lacking in the literature. Thus, we present here a study of the temperature dependence and recoil-free fraction of a series of synthetic olivines.

Sklute, E. C.; Rothstein, Y.; Dyar, M. D.; Schaefer, M. W.; Menzies, O. N.; Bland, P. A.; Berry, F. J.

2005-01-01

399

Hydration-induced climb dissociation of dislocations in naturally deformed mantle olivine  

NASA Astrophysics Data System (ADS)

Widely dissociated dislocations have been observed in mantle olivine from the Erro-Tobbio peridotite in N.W. Italy. Analysis of diffraction contrast in transmission electron microscopy (TEM) indicates that the dissociation reaction involves the climb dissociation on (001) and {021} planes of b=[001] unit dislocations into partial dislocations with Burgers vectors approximately equal to 1/x <011>. In the most extreme case a unit dislocation dissociates into four partials which bound three planar defects. The unusually wide dissociation and the greater extent of dissociation in olivine from amphibole-bearing rocks suggests that the dissociation is related to hydration. The occurrence of fluid inclusions along the dislocations confirms that the partials and planar defects are saturated with volatiles. Analysis of possible planar defect structures in Fo90 shows that; (i) the most likely partial Burgers vectors are b=<0 3/11 1/4>; (ii) two of the planar defects are cation-deficient and can be stabilised by segregation of H+ to produce (Mg, Fe) (OH)2 layers which are iso-structural with the OH-rich interlayer of the humite group minerals; (iii) the central planar defect is formed by removing a stoichiometric olivine (002) layer so does not produce any local chemical changes. The climb dissociation provides a possible mechanism for the transformation of olivine to a humite group mineral. OH-rich interlayers may nucleate on dislocations and extend into the crystal by climb resulting in a gradual increase of (Mg, Fe) (OH)2 content. The only addition of material required is hydrogen which can rapidly diffuse into olivine. If the dissociation is stable and occurs at high temperatures and pressures it may significantly influence the nature and kinetics of deformation mechanisms and the olivine — spinel shear transformation mechanism in hydrated olivine.

Drury, Martyn R.

1991-08-01

400

The legacy of crystal-plastic deformation in olivine: high-diffusivity pathways during serpentinization  

NASA Astrophysics Data System (ADS)

Crystal-plastic olivine deformation to produce subgrain boundaries composed of edge dislocations is an inevitable consequence of asthenospheric mantle flow. Although crystal-plastic deformation and serpentinization are spatio-temporally decoupled, we identified compositional readjustments expressed on the micrometric level as a striped Fe-enriched ( bar{X}_{text{Fe}} = 0.24 ± 0.02 (zones); 0.12 ± 0.02 (bulk)) or Fe-depleted ( bar{X}_{text{Fe}} = 0.10 ± 0.01 (zones); 0.13 ± 0.01 (bulk)) zoning in partly serpentinized olivine grains from two upper mantle sections in Norway. Focused ion beam sample preparation combined with transmission electron microscopy (TEM) and aberration-corrected scanning TEM, enabling atomic-level resolved electron energy-loss spectroscopic line profiling, reveals that every zone is immediately associated with a subgrain boundary. We infer that the zonings are a result of the environmental Fe2+Mg-1 exchange potential during antigorite serpentinization of olivine and the drive toward element exchange equilibrium. This is facilitated by enhanced solid-state diffusion along subgrain boundaries in a system, which otherwise re-equilibrates via dissolution-reprecipitation. Fe enrichment or depletion is controlled by the silica activity imposed on the system by the local olivine/orthopyroxene mass ratio, temperature and the effect of magnetite stability. The Fe-Mg exchange coefficients K_{text{D}}^{{{text{Atg}}/{text{Ol}}}} between both types of zoning and antigorite display coalescence toward exchange equilibrium. With both types of zoning, Mn is enriched and Ni depleted compared with the unaffected bulk composition. Nanometer-sized, heterogeneously distributed antigorite precipitates along olivine subgrain boundaries suggest that water was able to ingress along them. Crystallographic orientation relationships gained via electron backscatter diffraction between olivine grain domains and different serpentine vein generations support the hypothesis that serpentinization was initiated along olivine subgrain boundaries.

Plümper, Oliver; King, Helen E.; Vollmer, Christian; Ramasse, Quentin; Jung, Haemyeong; Austrheim, Håkon

2012-04-01

401

Single-Crystal Elasticity of San Carlos Olivine in the Earth's Mantle  

NASA Astrophysics Data System (ADS)

Based on the pyrolitic compositional model, olivine is the most abundant mineral in the Earth's upper mantle. Experimental and theoretical studies on physical, chemical, and transport properties of olivine have attracted extensive research interests over last decades and have greatly contributed to our understanding on the structure and composition of the Earth's upper mantle. Single-crystal elasticity of olivine at relevant pressure-temperature conditions is of particular importance in constraining the composition, interpreting the observed anisotropy, and understanding the seismic tomography and heterogeneity of the region. However, single-crystal elasticity of olivine has never been investigated at simultaneous high pressure-temperature conditions of the upper mantle. Much of our current knowledge on the velocity structures of the upper-mantle minerals heavily relies on extrapolations of limited mineral physics results. In this study, we have studied single-crystal elasticity of San Carlos olivine [(Mg0.9Fe0.1)2SiO4] up to 16 GPa and 750 K using Brillouin spectroscopy and X-ray diffraction in an externally-heated diamond anvil cell. We have derived full elastic tensors of the olivine at high pressure-temperature conditions, providing crucial constraints on the combined effects of pressure and temperature on the single-crystal elasticity of olivine. These results have been applied to model the velocity structures and seismic Vp/Vs anisotropies of the Earth's upper mantle and olivne mantle wedge in the subduction are by combing with literature deformation results. Here we will present these results to address current outstanding issues in the geophysics, geochemistry, and seismology of the upper mantle.

Mao, Z.; Lin, J.; Fan, D.; Yang, J.; Zhuravlev, K. K.; Tkachev, S. N.

2013-12-01

402

Pressure Dependence of Creep in Olivine and Its Implication to the Rheology of Upper Mantle  

NASA Astrophysics Data System (ADS)

Rheological properties of mantle minerals are critical for understanding the dynamics of Earth's deep interior. Polycrystalline olivine, which makes up more than 60 vol% of the mantle portion of oceanic lithosphere, predominantly represents the rheology of this region. Nevertheless, previous deformation experiments conducted at various pressures to measure the rheological properties of olivine at high temperature resulted in bimodal results. The activation volume (?V*) for creep of olivine reported from Griggs and Paterson apparatus at relatively lower pressures is ~15 cm3/mol or higher, while higher pressure studies from D-DIA apparatus report a ?V* near zero. In order to address this issue and provide a standard for strength comparison for various apparatus types, we are conducting a series of experiments on a synthetic polycrystalline forsterite, the Mg end member of olivine, in a modified Griggs apparatus with liquid pressure medium that is capable of high-quality measurement of stress during deformation experiments under confining pressure up to ?3 GPa. Our results show a tightly constrained ?V* of 11 cm3/mol, demonstrating a significant pressure dependence of creep in nominally dry olivine at pressure lower than 3 GPa. This latter result is almost identical to that for Mn2GeO4 olivine measured over the range 0.4 - 4.0 GPa (Bai & Green, 1998, Fig. 4a). We now intend to conduct comparable studies on forsterite in D-DIA in an overlapping pressure range to evaluate whether the difference in activation volume measurements is a result of the pressure dependence of creep of olivine or whether apparatus differences are involved.

Xia, G.; Zhang, J.; Green, H. W.

2012-12-01

403

Diffusion kinetics of Cr in olivine and 53Mn– 53Cr thermochronology of early solar system objects  

Microsoft Academic Search

We have determined the diffusion coefficient of Cr in olivine as function of temperature, oxygen fugacity (fO2), and crystallographic orientation and used these data to develop a quantitative understanding of the resetting of the short-lived 53Mn–53Cr decay system in olivine during cooling within meteorite parent body. The diffusion of Cr in olivine was found to be anisotropic, and effectively independent

Motoo Ito; Jibamitra Ganguly

2006-01-01

404

Partitioning of Ni between olivine and siliceous eclogite partial melt: experimental constraints on the mantle source of Hawaiian basalts  

Microsoft Academic Search

Olivine is abundant in Earth’s upper mantle and ubiquitous in basaltic lavas, but rarely occurs in eclogite. Partial melts\\u000a of eclogite are, therefore, not in equilibrium with olivine, and will react with peridotite as they migrate through the upper\\u000a mantle. If such melts erupt at Earth’s surface, their compositions will be highly modified and they may be olivine-saturated.\\u000a We investigated

Zhengrong Wang; Glenn A. Gaetani

2008-01-01

405

Shear wave attenuation and dispersion in melt-bearing olivine polycrystals: 2. Microstructural interpretation and seismological implications  

Microsoft Academic Search

The torsional forced oscillation tests of melt-bearing olivine aggregates reported by Jackson et al. [2004] consistently show a peak in attenuation that is absent from melt-free aggregates tested under similar conditions and grain sizes. Characterization by SEM shows that the melt resides in triple junction tubules and larger pockets as previously described. TEM imaging and EDS analysis reveals that olivine-olivine

Ulrich H. Faul; John D. Fitz Gerald; Ian Jackson

2004-01-01

406

Fayalitic olivine in CV3 chondrite matrix and dark inclusions: A nebular origin  

NASA Astrophysics Data System (ADS)

Fayalitic olivine (Fa>32) is the major component of the matrices and Dark Inclusions (DI) of CV3 and other unequilibrated chondrites. It occurs most commonly as rims, veins and halos in and around chondrule silicates in the Allende-type (CV3OxA) chondrites and to a much lesser extent in the reduced (CV3R) and Bali-type (CV3OxB) chondrites. The olivines have distinctive platy, tabular and lath- or irregular-shaped crystals, with the ratio the two types varying widely. In CV3OxB chondrites, matrix fayalitic olivines range up to Fa99.9, whereas in the other CV3 chondrites the range is much smaller. The platy and tabular anisotropic forms of the fayalitic olivines strongly suggest growth from a vapor and the nature of occurrences suggests that CV3 matrices are unequilibrated mixtures of nebular materials. We argue that the parent body hydration/dehydration model has numerous inconsistencies that make this hypothesis highly unlikely. These include: (1) There is no direct evidence linking fayalitic olivine to precursor phyllosilicates. (2) Dehydration of phyllosilicates cannot explain the wide range of morphologies of the fayalitic olivines. (3) Fayalitic olivine clearly predates the formation of the hydrous phases in CV3 chondrites and is one of the phases that breaks down to form phyllosilicates (Keller et al., 1994). (4) The unequilibrated nature of the matrix, including fine scale zoning in 10=B5-sized fayalitic olivine crystals, would not survive the parent body metamorphism required in the dehydration model. (5) A DI in the Ningqiang chondrite contains fayalitic olivine rimmed by glassy and microcrystalline material (Zolensky et al., 1997), which probably formed by radiation damage. This indicates that the fayalitic olivine was exposed to solar radiation in a nebular setting. (6) Some Allende chondrules contain unaltered primary, anhydrous glassy mesostasis in contact with the host matrix (e.g., Ikeda and Kimura, 1995). Chondrule mesostases would not have survived parent body hydration without becoming hydrated and would probably not survive the metamorphic heating required in the dehydration scenario. (7) Single platy and barrel-shaped crystals of fayalitic olivine are present in accretionary rims in CAIs (MacPherson and Davis, 1997), which developed in the nebula. (8) Matrix lumps completely encased in chondrules in ordinary chondrites contain mainly fayalitic olivine (Scott et al., 1984), indicating a nebular origin. (9) Oxygen isotopic compositions of Allende matrix and DIs strongly indicate little or no hydration for Allende and its components (Clayton, 1997). We favor a nebular vaporization/recondensation model in which vaporization of chondritic dust produced a fayalite-rich vapor, followed by formation of the fayalitic olivine by direct recondensation from the vapor, epitactic growth on surfaces of existing forsterite and enstatite in chondrules, and replacement of existing forsterite and enstatite by gas-solid exchange.

Weisberg, Michael K.; Prinz, Martin

1998-09-01

407

Calcium Zonation in Olivine: an Indicator for Cooling Rates at Low Temperatures  

NASA Astrophysics Data System (ADS)

The calcium content in lherzolitic olivines is known to be pressure and temperature (Kohler and Brey 1990) dependent. Application of Ca-zoning for determining cooling rates of meteorites is facilitated by the absence of pressure effects (Kohler et al. 1991). Since kamacite-taenite exsolution lamellae and Ca-zoning in olivine are formed within the same temperature range (650-400 degrees C), both methods can be compared. Extrapolation of high temperature Ca-diffusion coefficients to these low temperatures yields higher cooling rates (2 to 3 orders of magnitude) than metallographic cooling rates. We estimated low temperature Ca-diffusion coefficients from a comparison of Ca- zoning in Landes olivine and corresponding metallographic cooling rates, derived from metal grains in Landes silicate inclusions (30 degrees C+-10/10^6 y) (Herpfer and Larimer 1992). Preliminary data showed Ca-zoning in olivines of silicate inclusions in Caddo County (IAB) (Palme et al. 1991). Further Ca-profiles in Caddo County olivines were measured by SIMS (Caltech) to obtain a better understanding of Ca-zoning. All analyzed olivine grains are zoned from ~120 ppm Ca in the core to 60-50 ppm at the rim. Small grains have lower core contents. Corresponding to the highest Ca-cores the maximum temperature recorded in Caddo County olivine is 630 degrees C, about 250 degrees C lower than the 2- px-temperature. Several Ca-profiles were determined on a single olivine grain (ol 2) with known crystallographic orientation. The following conclusions can be drawn from our study: 1. Identical Ca-zoning patterns for all profiles in ol 2, reflecting similar low temperature Ca-diffusion coefficients for different crystallographic directions. This allows to calculate cooling rates from zonation profiles of randomly oriented olivine grains. 2. Ca-zoning is independent of the adjacent minerals (see Fig. 1). Ca-profiles at the ol-cpx, ol-ol, ol-plag and ol- metal contact are identical. Grain boundary diffusion is apparently so fast that ol-cpx equilibration can be maintained even if no cpx is in contact to olivine. 3. Calculated diffusion profiles can be fitted to the measured profiles (3) Confirming that Ca-zonation is the result of a diffusion controlled process. With the adapted diffusion coefficient a cooling rate between 10 and 50 degrees C/10^6 y is obtained for Caddo County silicate inclusions. A slight decrease of fayalite content towards the rim was observed in ol 2. This zoning is less pronounced than Ca- zoning and appears to be restricted to the ol-metal border, presumably reflecting a reduction process. In summary, we have demonstrated the feasibility for using Ca-zoning in olivine as a cooling rate indicator in IAB-silicate inclusions. The resolution appears to be somewhat lower than that of metallographic cooling rates. Low temperature Ca-diffusion data in olivine are required to establish Ca-diffusion as an independent method for cooling rate determination at low temperature in metal bearing as well as metal free systems. References Kohler T.P. and Brey G.P. (1990) Geochim. Cosmochim. Acta. 54. 2375-2388. Kohler T., Palme H., and Brey G. (1991) N. Jb. Miner. Mh. 9. 423-431. Herpfer M.A. and Larimer J.W. (1992) submitted to GCA. Palme H., Hutcheon I.D., Kennedy A.K., Sheng Y.J. and Spettel B. (1991) Lunar Planet. Sci. (abstract) 22, 1015-1016. Figure 1, which in the hard copy appears here, shows Ca zoning in olivine (SIMS) for Caddo County.

Zipfel, J.; Palme, H.; Kennedy, A. K.; Hutcheon, I. D.

1992-07-01

408

Effect of fO2 on the incorporation and diffusivity of Li in olivine  

NASA Astrophysics Data System (ADS)

Over the last decade the geochemical behaviour of Li has become of special interest since it was speculated that Li stable isotopes could be a promising tracer for subduction zone processes. However, there have been many studies of natural samples but our experimental and theoretical basis for interpreting these data is still lacking. Two diffusion mechanisms were identified for Li in olivine [1]. Their contribution to the net flux of Li in olivine depends on the vacancy concentration on the metal sites, which is sensitive to the fO2. Therefore we have studied the effect of fO2 on Li solubility and diffusion in olivine. Experimental approach: thin plates of crushed, natural olivine single crystals were embedded into two different kind of powders, ground plagioclase with about 2.5 ppm Li or a pre-annealed powder mixture of San Carlos olivine and isotopically enriched Li. All runs were performed in a gas-mixing furnace with fO2 controlled by flowing CO/CO2 mixture. In each run we simultaneously annealed about 100 micrometer-sized samples of Pakistan olivine and San Carlos olivine. In addition we have added to each run a mm sized crystallographically oriented parallelepiped of San Carlos olivine. For each powder reservoir we have performed a set of three anneals at 1200 C and different fO2. Cross sections of the run products were polished and analyzed with LA-ICP-MS. Results: In all cases the Li isotopes and concentrations were homogeneous in the 100 micrometer sized grains with one exception, the experiment at 1.e-10 bar with the highly enriched Li reservoir. The final Li concentration was slightly lower in the Pakistan than San Carlos olivine and was much lower in general if buffered by the plagioclase powder. Most importantly, the Li concentration increased systematically with increasing oxygen fugacity, indicating that the incorporation of Li in olivine is fO2 dependent. The mm-sized, oriented crystal was in most cases zoned and the extent of zoning depends on the diffusion direction. In addition the profiles became systematically longer with decreasing fugacity and at the most reducing conditions the crystal was almost homogenous. However, the isotopes were in all cases completely homogenized and equilibrated with the isotopically enriched reservoir. Thermodynamic model: We extended the quantitative point defect model for olivine [2] and reproduced the effect of fO2 on the solubility of Li when we assume it is mainly on the metal site and charge balanced by the formation of Fe3+ on the metal site. Conclusions: Our results strongly indicate that incorporation of Li is dependent on the fO2, less dependent on the trace element content. Diffusion of Li in olivine is anisotropic and dependent on fO2. Our quantitative point defect model for olivine underpins the experimental results. This will allow us to develop a multi-component diffusion model considering relevant point defects, e.g. Fe3+ and metal vacancies. Such a model will hopefully help us to simulate diffusion of Li at various natural circumstances including fO2 as a critical parameter. References: [1] Dohmen et al. (2010) Geochim Cosmochim Acta 74, 274-292; [2] Dohmen and Chakraborty (2007), Phys Chem Minerals 34, 597- 598.

Dohmen, R.; Coogan, L. A.

2012-12-01

409

Impact of geoengineering with olivine dissolution on the carbon cycle and marine biology  

NASA Astrophysics Data System (ADS)

We investigate the potential of a specific geoengineering technique: the carbon sequestration by artificially enhanced silicate weathering via the dissolution of olivine. This approach would not only operate against rising temperatures but would also oppose ocean acidification. If details of the marine chemistry are taken into consideration, a new mass ratio of CO2 sequestration per olivine dissolution of about 1 is achieved, 20% smaller than previously assumed. We calculate that this approach has the potential to sequestrate up to 1 Pg of C per year directly, if olivine is distributed as fine powder over land areas of the humid tropics, but this rate is limited by the saturation concentration of silicic acid. These upper limit sequestration rates come at the environmental cost of pH values in the rivers rising to 8.2 in examples for the rivers Amazon and Congo (Köhler et al., 2010). The secondary effects of the input of silicic acid connected with this approach leads in an ecosystem model (ReCOM2.0 in MITgcm) to species shifts aways from the calcifying species towards diatoms, thus altering the biological carbon pumps. Open ocean dissolution of olivine would sequestrate about 1 Pg CO2 per Pg olivine from which about 8% are caused by changes in the biological pumps (increase export of organic matter, decreased export of CaCO3). The chemical impact of open ocean dissolution of olivine (the increased alkalinity input) is therefore less efficient than dissolution on land, but leads due to different chemical impacts to a higher surface ocean pH enhancement to counteract ocean acidification. We finally investigate open ocean dissolution rates of up to 10 Pg olivine per year corresponding to geoengineering rates which might be of interest in the light of expected future emission (e.g. A2 scenario with emissions rising to 30 PgC/yr in 2100 AD). Those rates would still sequestrate only less than 20% of the emission until 2100, but would require that the nowadays available shipping capacity of tankers and bulk carriers is entirely used for olivine dissolution ten times a year. Reference Köhler, P.; Hartmann, J. and Wolf-Gladrow, D. A. (2010) Geoengineering potential of artificially enhanced silicate weathering of olivine, Proceedings of the National Academy of Science 107, 20228-20233, doi: 10.1073/pnas.1000545107.

Köhler, P.; Abrams, J.; Völker, C.; Wolf-Gladrow, D. A.; Hartmann, J.

2012-04-01

410

Sulfide mineralization in magmas: Investigating the effect of re-equilibrating olivine xenocrysts  

NASA Astrophysics Data System (ADS)

Large amounts of entrained olivine xenocrysts are common features of many mafic magmas. It is only natural that mantle derived melts mechanically destabilize and incorporate disaggregated wall rock material during ascension and transport. Bowen noticed this in 1928 and many subsequent studies at, for example, Kilauea have noted an abundance of these 'Tramp Crystals' in proportion to the eruptive flux. These olivines are distinguished by their high, nonequilibrium magnesium contents (Fo:88-92), and, due to the very fast interdiffusion rates of iron and magnesium in olivine (~10-7-10-9 mm2/s), these crystals are often rimmed in iron-rich olivine, or, if given enough time, become completely re-equilibrated with the surrounding melt. Because this exchange occurs in a finite volume of liquid, the composition of the liquid during xenocryst re-equilibration may be strongly affected and driven from its normal course of evolution. The magnitude of this change is clearly a function of the relative amount of xenocrysts and the compositional difference between liquid and crystals. Because mantle olivine is always more forsteritic than the equilibrium olivine composition of the liquid, re-equilibration of olivine increases the magnesium content and decreases the iron content of the liquid. A possible outcome is a decrease in the saturation point of sulfide. The saturation point of sulfide in magmas is sensitive to the concentration of iron. This is a fundamentally important consideration, given the fact that the PGE content of sulfides reflects the cumulative amount of magma the sulfide "sees," and higher temperature saturation greatly increases the odds of sulfide existence and longevity. Presented is a model predicting sulfide saturation with varying loads of xenocrystic olivine within a solidifying body. Even at high temperatures, reasonable fractions of xenocrysts can lower the sulfide saturation concentration over 200 ppm. The model is then compared to a world-class sulfide ore body that is loaded with olivine crystals-the Jinchuan ore body, China, and provides a reasonable, alternative explanation for sulfide formation and deposition.

Currier, R. M.; Marsh, B. D.

2011-12-01

411

Investigation into the Effect of H2O on Olivine-Ringwoodite Transformation Kinetics  

NASA Astrophysics Data System (ADS)

The rapid transformation of metastable olivine subducted into the transition zone has been proposed as a mechanism leading to deep focus earthquakes, as well as general rheological weakening of the subducting slab. In evaluation of this hypothesis, several experimental studies have derived olivine-ringwoodite transformation rates for dry systems. However, double-seismic zones in subducting slabs suggest significant hydration and serpentinization. This likely presence of H2O could be expected to significantly enhance the kinetics of the olivine-ringwoodite transformation, reducing the depth to which metastable olivine would persist in the transition zone. We have initiated a series of experiments to systematically investigate the effect of dissolved water on the transformation kinetics of olivine to its high-pressure polymorphs, ringwoodite and wadsleyite. Single crystals of San Carlos olivine were milled and sieved to produce spheres with a diameter of 450-500 microns. These crystals were then hot-pressed in a matrix of olivine and enstatite powder, and deuterated by welding liquid D2O inside the sample capsule during piston-cylinder experiments. The use of D2O as a proxy for H22O was made to ease SIMS analysis because of the high background for H2O. All deuteration experiments were conducted with a nickel/nickel oxide oxygen fugacity buffer. Run conditions ranged from 2-3.2 GPa and 1000-1050 oC. The single-crystal San Carlos olivine spheres in the run products were found to contain 150-400 ppm D2O by weight. The deuterated olivine spheres and hot-pressed matrix were cut into 1.5 mm cubes and are being used as starting material in experiments conducted in the wadsleyite and ringwoodite stability fields. These experiments are being performed in a multi-anvil apparatus for durations ranging from 30-240 minutes. Run products will be prepared as thin sections and the thickness of the reaction rims will be measured and related to run duration to infer transformation rates as a function of temperature, pressure, and water content. TEM analysis will be used to determine the effect of D2O on the transformation mechanisms.

Diedrich, T. R.; Sharp, T.; Leinenweber, K.; Hervig, R.

2004-12-01

412

An Empirical Calibration of an Al-in-olivine Geothermometer for Mantle-derived Materials  

NASA Astrophysics Data System (ADS)

The concentration of aluminum in olivine from mantle peridotites is variable and strongly temperature dependent, and can therefore be used as a geothermometer. A suite of fresh mantle peridotite xenoliths from the Kaalvallei kimberlite (South-Africa) was used for calibration of the thermometer. The samples contain olivine, opx, cpx, garnet ± spinel. Aluminum contents of the olivines, determined by LA-ICP-MS, range from 8-140 ppm, with a few anomalous values up to 310 ppm. Mg# lie between 91.5 and 93.3. P-T conditions for the peridotites were estimated with the Al-in-opx geobarometer and cpx-opx geothermometer [1], and plot on a conductive geotherm of ca. 40 mW/m2. The temperature range is 900-1380° C. Only samples plotting on the geotherm were considered, as the others showed disequilibrium features. The expression for the thermometer is: T{Al-in-ol }(° C) = 11390 / [ 11.88 - ln(ppm Al) ] - 273 with an average residual of 12° C. As the compositional range of mantle olivine is very small, no correction for major chemical components is necessary. In addition, no correction for Al activity of the system is necessary, as long as an Al-saturated phase such as garnet is present. Combined with the Ca-in-olivine barometer [2], the new thermometer has the potential to determine P-T conditions of single olivines. As olivine is an abundant component of heavy mineral separates from kimberlites, it could serve as a new tool for diamond exploration. Vanadium and Cr show similar temperature-dependent variations to Al, but to a lesser degree, and would therefore yield less accurate geothermometers. In addition, partitioning of these elements is sensitive to variations in oxidation state. The pressure dependence of the thermometer is the subject of future research. Considering the significant pressure effect on Ca and Ti partitioning into olivine, it is recommended that the Al-in-olivine thermometer in its current form is applied to rocks derived from comparable (cratonic) geotherms only. [1] Brey and Kohler, 1990, J Petrol, 31, 1353-1378 [2] Kohler and Brey, 1990, GCA, 54:2375-2388

de Hoog, J. C.

2004-12-01

413

Space weathering simulations through controlled growth of iron nanoparticles on olivine  

NASA Astrophysics Data System (ADS)

Airless planetary bodies are directly exposed to space weathering. The main spectral effects of space weathering are darkening, reduction in intensity of silicate mineral absorption bands, and an increase in the spectral slope towards longer wavelengths (reddening). Production of nanophase metallic iron (npFe0) during space weathering plays major role in these spectral changes. A laboratory procedure for the controlled production of npFe0 in silicate mineral powders has been developed. The method is based on a two-step thermal treatment of low-iron olivine, first in ambient air and then in hydrogen atmosphere. Through this process, a series of olivine powder samples was prepared with varying amounts of npFe0 in the 7-20 nm size range. A logarithmic trend is observed between amount of npFe0 and darkening, reduction of 1 ?m olivine absorption band, reddening, and 1 ?m band width. Olivine with a population of physically larger npFe0 particles follows spectral trends similar to other samples, except for the reddening trend. This is interpreted as the larger, ?40-50 nm sized, npFe0 particles do not contribute to the spectral slope change as efficiently as the smaller npFe0 fraction. A linear trend is observed between the amount of npFe0 and 1 ?m band center position, most likely caused by Fe2+ disassociation from olivine structure into npFe0 particles.

Kohout, Tomáš; ?uda, Jan; Filip, Jan; Britt, Daniel; Bradley, Todd; Tu?ek, Ji?í; Skála, Roman; Kletetschka, Gunther; Kašlík, Josef; Malina, Ond?ej; Šišková, Karolína; Zbo?il, Radek

2014-07-01

414

Spatial correlation of deformation and mineral reaction in experimentally deformed plagioclase olivine aggregates  

NASA Astrophysics Data System (ADS)

Shear deformation of hot pressed plagioclase-olivine aggregates was studied in the presence and absence of mineral reaction. Experiments were performed at 900 °C, 1500 MPa, and a constant shear strain rate of ˜5×10 -5 s -1 in a solid medium apparatus. Whether the mineral reaction between plagioclase and olivine takes place or not is controlled by choosing the appropriate plagioclase composition; labradorite (An 60) does not react, anorthite (An 92) does. Labradorite-olivine aggregates deformed without reaction are very strong and show strain hardening throughout the experiment. Syndeformational reaction between olivine and anorthite causes a pronounced strain weakening. The reaction produces fine-grained opx-cpx-spinel aggregates, which accommodate a large fraction of the finite strain. Deformation and reaction are localised within a 0.5-mm-wide sample. Three representative samples were analysed for their fabric anisotropy R* and shape-preferred orientation ?* (fabric angle with the shear plane) using the autocorrelation function (ACF). Fabric anisotropy can be calibrated to quantify strain variations across the sheared samples. In the deformed and reacted anorthite-olivine aggregate, there is a strong correlation between reaction progress and strain; regions of large shear strain correspond to regions of maximum reaction progress. Within the sample, the derived strain rate variations range up to almost one order of magnitude.

de Ronde, A. A.; Heilbronner, R.; Stünitz, H.; Tullis, J.

2004-09-01

415

Shock-induced fine-grained recrystallization of olivine - Evidence against subsolidus reduction of Fe/2+/  

NASA Technical Reports Server (NTRS)

Electron spin resonance (ESR) studies have been carried out on three single grains of terrestrial olivine (Fo90) shock loaded along the 010 line to peak pressures of 280, 330, and 440 kbar. The results indicate that neither metallic Fe similar to that observed in returned lunar soils nor paramagnetic Fe(3+) caused by oxidation of Fe(2+) has been produced in these shock experiments. Trace amounts of Mn (2+) have been detected in both shocked and unshocked olivine. The ESR signals of Mn(2+) show spectral features which are found to correlate with the degree of shock-induced recrystallization observed petrographically. The increasing mass fraction of recrystallized olivine correlates with increasing shock pressures. This phenomenon is modelled assuming it results from the progressive effect of the shock-induced transformation of the olivine to a yet unknown high-pressure phase and its subsequent reversion to the low-pressure olivine phase. The mass fraction of recrystallized material is predicted to be nearly linear with shock pressure.

Ahrens, T. J.; Tsay, F.-D.; Live, D. H.

1976-01-01

416

Fayalitic Olivine in Matrix of the Krymka LL3.1 Chondrite  

NASA Astrophysics Data System (ADS)

INTRODUCTION. Matrix persists as one of the most poorly characterized chondritic components. Its aggregational nature makes it an excellent place to search for primitive chondritic components that prevailed in the nebula during and after chondrule formation as well as components recording processes that predated and postdated accretion. In this study we focus on the occurrence and formation of the fayalitic olivine in the matrix of the Krymka LL3.1 unequilibrated ordinary chondrite. RESULTS. We limited our study to matrix areas clearly sandwiched between chondrules and did not include chondrule rims. In Krymka, matrix is coarser-grained and more Fe-rich than the rim material. Matrix is also highly variable in the size, shape and composition of its components, whereas chondrule rims appear more uniform. Krymka matrix is an aggregation of diverse mineral and lithic components. Mineral components include olivine, enstatite, diopsidic pyroxene, Ti-Al-rich Ca-pyroxene, hedenbergite, amorphous silicate material, spinel, oxides, troilite, and metal. Olivine is clearly dominant (~75% normative) and occurs in a variety of textures and compositions. Fayalitic olivine (Fa(sub)(58-94), avg.=Fa(sub)(72)) is ubiquitous throughout the matrix and occurs as (1) Isolated platelets (typically 1-3 micrometers x 3-5 micrometers, with some up to 10 micrometers in length), (2) Platelet clusters, which include randomly oriented platelets and/or intergrown platelets, (3) Platelet overgrowths which are overgrowths of parallel platelets on surfaces of larger (10-300 micrometers), more magnesian (Fa(sub)(4-34), avg.=Fa(sub)(19)) olivine fragments, (4) Euhedral-subhedral crystals (1-10 micrometers) which are often associated with and compositionally similar to platelets, and (5) Fluffy aggregates - irregularly shaped porous aggregates of submicron crystals. TEM study of the overgrowths reveals that the direction of elongation of the fayalitic platelets is along the c axis corresponding with the c direction of the larger olivine substrate. The larger, more magnesian olivine fragments are generally single crystals, but in some cases are associated with pyroxene (Fs(sub)(5-27),Wo(sub)(0.5-2)) or high-Ca pyroxene. These larger olivines are compositionally similar to chondrule olivines, whereas the fayalitic platelets are texturally and compositionally unlike olivines in chondrules. Fayalitic olivine with morphologies similar to those in Krymka matrix occur in the Chainpur LL3.4 and Ngawi LL3 matrix, but are much less common. These textures may have been characteristic of all primitive ordinary chondrite matrix, but were generally overprinted by metamorphic recrystallization. DISCUSSION: Fayalitic olivine in Krymka matrix records a process that has i