The Experts below are selected from a list of 5322 Experts worldwide ranked by ideXlab platform
Osamu Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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orientation dependence of li ion diffusion kinetics in licoo2 thin films prepared by rf magnetron sputtering
Solid State Ionics, 2008Co-Authors: Jian Xie, Nobuyuki Imanishi, T Matsumura, Atsushi Hirano, Y Takeda, Osamu YamamotoAbstract:Abstract LiCoO2 thin films with different orientations were prepared by radio frequency (RF) magnetron sputtering. The Li–ion chemical diffusion coefficients, DLi, were measured using cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT), potentiostatic intermittent titration technique (PITT), and electrochemical impedance spectroscopy (EIS). It was found that the LiCoO2 thin film orientation depends on the thickness of the film. A LiCoO2 thin film with a thickness of 0.31 μm shows a high (003) orientation and that with 1.35 μm thickness exhibits high (104) orientation. The (104) oriented thin film exhibits a larger DLi value than that of the (003) oriented thin film. The lithium ion conductivity of LiCoO2 was measured with the help of a Li/lithium ion conducting polymer/Li1 − δCoO2/lithium ion conducting polymer/Li cell. The ionic conductivity obtained was compared with that obtained from the chemical diffusion coefficient of the thin films. The ionic conductivity estimated from the PITT results was a close comparison with that measured by the electron blocking method.
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kinetics investigation of a preferential 104 plane oriented licoo2 thin film prepared by rf magnetron sputtering
Solid State Ionics, 2007Co-Authors: Nobuyuki Imanishi, Atsushi Hirano, Y Takeda, M Matsumura, Osamu YamamotoAbstract:Abstract LiCoO 2 thin films with a preferential (104) orientation were prepared on Au substrates by radio frequency magnetron sputtering. The Li–ion chemical diffusion coefficients D˜ Li were measured by cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT), potentiostatic intermittent titration technique (PITT), and electrochemical impedance spectroscopy (EIS). The D˜ Li values depended on the content of Li in Li 1− δ CoO 2 . The D˜ Li values by GITT and PITT were in the range of 10 − 10 –10 − 12 cm 2 s − 1 and 10 − 11 –10 − 12 cm 2 s − 1 , respectively, and those by EIS varied over a more wide rang of from 10 − 9 to 10 − 12 cm 2 s − 1 . It was found that the D˜ Li values from different methods showed thickness independent. The D˜ Li values from different methods were compared with those reported previously.
Yangtse Cheng - One of the best experts on this subject based on the ideXlab platform.
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potentiostatic intermittent titration technique pitt for spherical particles with finite interfacial kinetics
Electrochimica Acta, 2012Co-Authors: Fuqian Yang, Xingcheng Xiao, Mark W Verbrugge, Yangtse ChengAbstract:The potentiostatic intermittent titration technique (PITT) is an electroanalytical method that has been widely used to study diffusion of solutes (such as lithium) in electrode materials. Here, we extend the conventional PITT method to account for finite interfacial reaction kinetics and derive analytic equations for electric current under PITT operations. Using the modified PITT, the lithium diffusion coefficient in host materials and the interfacial reaction kinetics can be determined simultaneously. We demonstrate this modified PITT by an example of lithium diffusion in graphite (mesocarbon microbeads, MCMB) and show the improvements of the modified PITT theory over the conventional PITT for investigating the kinetics of electrodes comprising spherical particles.
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potentiostatic intermittent titration technique for electrodes governed by diffusion and interfacial reaction
Journal of Physical Chemistry C, 2012Co-Authors: Xingcheng Xiao, Fuqian Yang, Mark W Verbrugge, Yangtse ChengAbstract:The potentiostatic intermittent titration technique (PITT) is one of the widely used methods for determining the diffusion coefficient in electrochemical materials, such as lithium diffusion in lithium-ion battery electrodes. The conventional PITT analysis neglects interfacial resistance and assumes the system is diffusion-controlled. For real electrode systems, however, surface reaction as well as diffusion may be rate-limiting. In this Article, we analyze PITT measurements for material systems with finite surface reaction rates. For small amplitude potential steps, we derive analytic solutions for the measured transient current associated with PITT, taking into account the effects of finite surface reaction rates. Using the analytic solutions, the diffusion coefficient, surface reaction rate, and the exchange current density can be determined simultaneously. An example of lithium diffusion in amorphous silicon thin-film electrodes is used to demonstrate the enhanced PITT approach.
Aleksandr V. Ivanishchev - One of the best experts on this subject based on the ideXlab platform.
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structural and electrochemical study of fast li diffusion in li3v2 po4 3 based electrode material
Electrochimica Acta, 2017Co-Authors: Aleksandr V. Ivanishchev, A V Churikov, Irina A. Ivanishcheva, A V Ushakov, Andrei V Mironov, Stanislav S Fedotov, Nellie R Khasanova, E V AntipovAbstract:Abstract NASICON-type lithium-vanadium phosphate (Li 3 V 2 (PO 4 ) 3 ) based electrodes capable to provide extremely fast lithium transport properties were studied by a combination of structure, morphology and surface characterization methods: X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), laser diffraction particle size distribution (PSD), as well as electrochemical methods: potentiostatic (PITT) and galvanostatic (GITT) intermittent titration techniques, electrochemical impedance spectroscopy (EIS), and constant current chronopotentiometry. Significant differences in the kinetics of reversible lithium intercalation depending on the lithiation stage were found: lithium diffusion coefficients, found from the PITT, GITT and EIS data, demonstrate an abrupt drop by 2–3 orders of magnitude (from 10 −9 to 10 −12 cm 2 s −1 ) in the 4.3–4.4 V potential range vs Li/Li + , which is attributed to the LiV 2 (PO 4 ) 3 ↔ V 2 (PO 4 ) 3 phase transition. The electrochemical extraction/insertion of two lithium equivalents can occur at ultra-high rates (up to 320C) from/into structurally more accessible Li2 and Li3 sites, while the de/intercalation of the third lithium equivalent from/into the Li1 position is supposedly hindered kinetically. To analyze the electrochemical data, specially developed theoretical models were used, which take into account geometry and phase configuration of the diffusion space, as well as the properties of the phase boundary interfaces. Morphology and size distribution parameters, essential for mathematical processing of the electrochemical data, were obtained by SEM, PSD and BET methods.
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lithium diffusion in li3v2 po4 3 based electrodes a joint analysis of electrochemical impedance cyclic voltammetry pulse chronoamperometry and chronopotentiometry data
Ionics, 2016Co-Authors: Aleksandr V. Ivanishchev, A V Churikov, Irina A. Ivanishcheva, Anatolevich Vyacheslav UshakovAbstract:In order to establish the mechanism and to determine the parameters of lithium transport in electrodes based on lithium-vanadium phosphate (Li3V2(PO4)3), the kinetic model was designed and experimentally tested for joint analysis of electrochemical impedance (EIS), cyclic voltammetry (CV), pulse chronoamperometry (PITT), and chronopotentiometry (GITT) data. It comprises the stages of sequential lithium-ion transfer in the surface layer and the bulk of electrode material’s particles, including accumulation of lithium in the bulk. Transfer processes at both sites are of diffusion nature and differ significantly, both by temporal (characteristic time, τ) and kinetic (diffusion coefficient, D) constants. PITT data analysis provided the following D values for the predominantly lithiated and delithiated forms of the intercalation material: 10−9 and 3 × 10−10 cm2 s−1, respectively, for transfer in the bulk and 10−12 cm2 s−1 for transfer in the thin surface layer of material’s particles. D values extracted from GITT data are in consistency with those obtained from PITT: 3.5–5.8 × 10−10 and 0.9–5 × 10−10 cm2 s−1 (for the current and currentless mode, respectively). The D values obtained from EIS data were 5.5 × 10−10 cm2 s−1 for lithiated (at a potential of 3.5 V) and 2.3 × 10−9 cm2 s−1 for delithiated (at a potential 4.1 V) forms. CV evaluation gave close results: 3 × 10−11 cm2 s−1 for anodic and 3.4 × 10−11 cm2 s−1 for cathodic processes, respectively. The use of complex experimental measurement procedure for combined application of the EIS, PITT, and GITT methods allowed to obtain thermodynamic E,c dependence of Li3V2(PO4)3 electrode, which is not affected by polarization and heterogeneity of lithium concentration in the intercalate.
Eric C Leuthardt - One of the best experts on this subject based on the ideXlab platform.
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glioblastoma treated with magnetic resonance imaging guided laser interstitial thermal therapy safety efficacy and outcomes
Neurosurgery, 2019Co-Authors: Ashwin A Kamath, Daniel D Friedman, Hassan S Akbari, Albert H Kim, Yu Tao, Jinqin Luo, Eric C LeuthardtAbstract:Background Despite the multitude of available treatments, glioblastoma (GBM) remains an aggressive and uniformly fatal tumor. Laser interstitial thermal therapy (LITT) is a novel, minimally invasive treatment that holds promise for treating patients with GBM who are not candidates for traditional open craniotomy. However, due to the recent introduction of LITT into clinical practice, large series that evaluate safety and long-term outcomes after LITT are lacking. Objective To present our institution's series of over 50 GBM patients treated with LITT, with regard to safety, efficacy, and outcomes. Methods We performed a retrospective descriptive study of patients with histologically proven GBM who underwent LITT. Data collected included demographics, tumor location and volume, tumor genetic markers, treatment volume, perioperative complications, and long-term follow-up data. Results We performed 58 LITT treatments for GBM in 54 patients over 5.5 yr. Forty-one were recurrent tumors while 17 were frontline treatments. Forty GBMs were lobar in location, while 18 were in deep structures (thalamus, insula, corpus callosum). Average tumor volume was 12.5 ± 13.4 cm3. Average percentage of tumor treated with the yellow thermal damage threshold (TDT) line (dose equivalent of 43°C for 2 min) was 93.3% ± 10.6%, and with the blue TDT line (dose equivalent of 43°C for 10 min) was 88.0% ± 14.2%. There were 7 perioperative complications (12%) and 2 mortalities (3.4%). Median overall survival after LITT for the total cohort was 11.5 mo, and median progression-free survival 6.6 mo. Conclusion LITT appears to be a safe and effective treatment for GBM in properly selected patients.
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magnetic resonance imaging guided focused laser interstitial thermal therapy for intracranial lesions single institution series
Neurosurgery, 2013Co-Authors: Ammar H Hawasli, Swapnil Bagade, Joshua S Shimony, Michelle M Millerthomas, Eric C LeuthardtAbstract:BACKGROUND: Surgical treatments for deep-seated intracranial lesions have been limited by morbidities associated with resection. Real-time magnetic resonance imaging– guided focused laser interstitial thermal therapy (LITT) offers a minimally invasive surgical treatment option for such lesions. OBJECTIVE: To review treatments and results of patients treated with LITT for intracranial lesions at Washington University School of Medicine. METHODS: In a review of 17 prospectively recruited LITT patients (34-78 years of age; mean, 59 years), we report demographics, treatment details, postoperative imaging characteristics, and peri- and postoperative clinical courses. RESULTS: Targets included 11 gliomas, 5 brain metastases, and 1 epilepsy focus. Lesions were lobar (n = 8), thalamic/basal ganglia (n = 5), insular (n = 3), and corpus callosum (n = 1). Mean target volume was 11.6 cm 3 , and LITT produced 93% target ablation. Patients with superficial lesions had shorter intensive care unit stays. Ten patients experienced no perioperative morbidities. Morbidities included transient aphasia, hemiparesis, hyponatremia, deep venous thrombosis, and fatal meningitis. Postoperative magnetic resonance imaging showed blood products within the lesion surrounded by new thin uniform rim of contrast enhancement and diffusion restriction. In conjunction with other therapies, LITT targets often showed stable or reduced local disease. Epilepsy focus LITT produced seizure freedom at 8 months. Preliminary overall median progression-free survival and survival from LITT in tumor patients were 7.6 and 10.9 months, respectively. However, this small cohort has not been followed for a sufficient length of time, necessitating future outcomes studies. CONCLUSION: Early peri- and postoperative clinical data demonstrate that LITT is a safe and viable ablative treatment option for intracranial lesions, and may be considered for select patients.
Nobuyuki Imanishi - One of the best experts on this subject based on the ideXlab platform.
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orientation dependence of li ion diffusion kinetics in licoo2 thin films prepared by rf magnetron sputtering
Solid State Ionics, 2008Co-Authors: Jian Xie, Nobuyuki Imanishi, T Matsumura, Atsushi Hirano, Y Takeda, Osamu YamamotoAbstract:Abstract LiCoO2 thin films with different orientations were prepared by radio frequency (RF) magnetron sputtering. The Li–ion chemical diffusion coefficients, DLi, were measured using cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT), potentiostatic intermittent titration technique (PITT), and electrochemical impedance spectroscopy (EIS). It was found that the LiCoO2 thin film orientation depends on the thickness of the film. A LiCoO2 thin film with a thickness of 0.31 μm shows a high (003) orientation and that with 1.35 μm thickness exhibits high (104) orientation. The (104) oriented thin film exhibits a larger DLi value than that of the (003) oriented thin film. The lithium ion conductivity of LiCoO2 was measured with the help of a Li/lithium ion conducting polymer/Li1 − δCoO2/lithium ion conducting polymer/Li cell. The ionic conductivity obtained was compared with that obtained from the chemical diffusion coefficient of the thin films. The ionic conductivity estimated from the PITT results was a close comparison with that measured by the electron blocking method.
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kinetics investigation of a preferential 104 plane oriented licoo2 thin film prepared by rf magnetron sputtering
Solid State Ionics, 2007Co-Authors: Nobuyuki Imanishi, Atsushi Hirano, Y Takeda, M Matsumura, Osamu YamamotoAbstract:Abstract LiCoO 2 thin films with a preferential (104) orientation were prepared on Au substrates by radio frequency magnetron sputtering. The Li–ion chemical diffusion coefficients D˜ Li were measured by cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT), potentiostatic intermittent titration technique (PITT), and electrochemical impedance spectroscopy (EIS). The D˜ Li values depended on the content of Li in Li 1− δ CoO 2 . The D˜ Li values by GITT and PITT were in the range of 10 − 10 –10 − 12 cm 2 s − 1 and 10 − 11 –10 − 12 cm 2 s − 1 , respectively, and those by EIS varied over a more wide rang of from 10 − 9 to 10 − 12 cm 2 s − 1 . It was found that the D˜ Li values from different methods showed thickness independent. The D˜ Li values from different methods were compared with those reported previously.
