Characterization of Ionic Transport in Li2O-(Mn:Fe)2O3-P2O5 Glasses for Li Batteries.

We present a systematic study of the lithium-ion transport upon the mixed manganese-iron oxide phosphate glasses 3Li2O-xMn2O3-(2-x)Fe2O3-3P2O5(LMxF2−xPO; 0≤ x ≤2.0) proposed for the use in a cathode for lithium secondary batteries. The glasses have been fabricated using a solid reaction process. The electrical characteristics of the glass samples have been characterized by electrical impedance in the frequency range from 100 Hz to 30 MHz and temperature from 30 °C to 240 °C. Differential thermal analysis and X-ray diffraction were used to determine the thermal and structural properties. It has been observed that the dc conductivity decreases, but the activation energies of dc and ac and the glass-forming ability increase with the increasing Mn2O3 content in LMxF2−xPO glasses. The process of the ionic conduction and the relaxation in LMxF2−xPO glasses are determined by using power−law, Cole−Cole, and modulus methods. The Li+ ions migrate via the conduction pathway of the non-bridging oxygen formed by the depolymerization of the mixed iron−manganese−phosphate network structure. The mixed iron−manganese content in the LMxF2−xPO glasses constructs the sites with different depths of the potential well, leading to low ionic conductivity.

Insight into Electrical and Dielectric Relaxation of Doped Tellurite Lithium-Silicate Glasses with Regard to Ionic Charge Carrier Number Density Estimation.

We investigate the role of tellurite on a lithium-silicate glass 0.1 TeO2 -0.90.1 TeO2 -0.9 (Li2O-2SiO2) (LSTO) system proposed for the use in solid electrolyte for lithium ion batteries. The measurements of electrical impedance are performed in the frequency 100 Hz-30 MHz and temperature from 50 to 150 °C. The electrical conductivity of LSTO glass increases compared with that of Li2O-2SiO2 (LSO) glass due to an increase in the number of Li+ ions. The ionic hopping and relaxation processes in disordered solids are generally explained using Cole-Cole, power law and modulus representations. The power law conductivity analysis, which is driven by the modified Rayleigh equation, presents the estimation of the number of ionic charge carriers explicitly. The estimation counts for direct contribution of about a 14% increase in direct current conductivity in the case of TeO2 doping. The relaxation process by modulus analysis confirms that the cations are trapped strongly in the potential wells. Both the direct current and alternating current activation energies (0.62-0.67 eV) for conduction in the LSO glass are the same as those in the LSTO glass.

Formation kinetics of Sr0.25Ba0.75Nb2O6 and Li2B4O7 crystals from 0.25SrO-0.75BaO-Nb2O5-Li2O-2B2O3 glass.

We have investigated the transition kinetics of Sr0.25Ba0.75Nb2O6 (SBN) and Li2B4O7 (LBO) crystals from 0.25SrO-0.75BaO-Nb2O5-Li2O-2B2O3 (SBNLBO) glass under isothermal and non-isothermal processes. With increasing temperature, there are two consecutive steps of crystallization of SBN and LBO from the glass. The Johnson-Mehl-Avrami function indicates that the crystallization mechanism of SBN belongs to an increasing nucleation rate with diffusion-controlled growth. The crystallite size of SBN ranges from 40 to 140 nm but it is confined to within 30-45 nm for LBO during the whole crystallization process. The relationship between the nano size and strain of SBN based on the Williamson-Hall method, and the change of activation energies of SBN and LBO crystallization analyzed by using the isoconversional model are discussed. A comparison of phonon modes between as-quenched glass and fully transformed crystals clearly shows that the low dimensional vibration modes in the structurally disordered glass change to highly dimensional network units with the formation of crystals.

Nonlinear analysis of heart rate variability during Qi therapy (external Qigong).

Heart rate variability (HRV) was compared in 30 subjects receiving external Qi therapy (EQT) or placebo control therapy, in a crossover design experiment. Subjects who received the EQT reported more pleasant and calm emotions than did the placebo group. Qi therapy reduced the heart rate and increased HRV as indicated by a reduced low frequency/high frequency power ratio of HRV. With nonlinear analysis, the Poincaré plot index of HRV and approximate entropy was greater in the EQT group than in the control group. These findings suggest that EQT stabilizes the sympathovagal function and cardiac autonomic nervous system by inducing more positive emotions than the placebo therapy. In conclusion, EQT may act by stabilizing both the autonomic nervous system and the emotional state.

Effects of Korean traditional herbal remedy on heart rate variability: linear and nonlinear analysis.

Heart rate variability was compared in 20 subjects taking traditional herbal remedy (Ondamtanggamibang) or placebo control pill, in placebo controlled design experiment. Herbal remedy group reported more pleasant and clam emotions than did the placebo group. Herbal remedy reduced the heart rate and increased heart rate variability (HRV) as indicated by a reduced low frequency/high frequency power ratio of heart rate variability. With nonlinear analysis, the Poincaré plot index of HRV and approximate entropy was greater in the herbal remedy group than in the control group. These findings suggest that herbal remedy stabilizes the sympathovagal function and cardiac autonomic nervous system by inducing more positive emotions than does placebo therapy. In conclusion, herbal remedy may act by stabilizing both the autonomic nervous system and the emotional state.

Effects of external qi-therapy on emotions, electroencephalograms, and plasma cortisol.

The authors investigated the effect of external Qi-therapy (EQT) on changes in encephalograms (EEGs) and circulating cortisol concentrations. Ten college students participated in crossover sessions, receiving EQT or placebo treatment with their eyes open. Subjects reported improved emotions of satisfaction, relaxation, and calmness during EQT as compared to levels reported during placebo treatments. There were significant differences in the proportions of alpha and beta EEG waves between the two sessions, and the relative strengths of alpha waves were higher during EQT than during control sessions (p < .05). Plasma cortisol concentrations during EQT were significantly lower than during control sessions p < .05). Thus, Qi-therapy was more effective in inducing relaxation than placebo treatment.