M. I. Pantyukhina

Synthesis and Electrical Properties of Lithium Metazirconate

Lithium metazirconate Li2ZrO3 with a monoclinic lattice is synthesized; the lattice parameters are: a = 0.5432 nm, b = 0.5427 nm, c = 0.903 nm, γ = 112.72°, and Z = 4. The conductivity of both the stoichiometric compound and samples rich or deficient in Li2O near this composition is determined. The conductivity of the synthesized compound reaches 0.029 S cm–1 at 600°C. The activation energy for the high-temperature segment is 13.8 kJ mol–1. An abnormal behavior (abrupt jump) of the temperature dependence of the conductivity at 430°C is discovered and attributed to a phase transition. The change in the structure in this temperature domain (400 to 500°C) is corroborated by the high-temperature X-ray analysis.

Lithium ion conductivity of LiLaO2-Li2ZrO3 solid solutions

The limits of the LiLaO2-and Li2ZrO3-based solid solutions in the LiLaO2-Li2ZrO3 system have been determined: 0–10 mol % Li2ZrO3 and 0–5 mol % LiLaO2, respectively. We have studied the transport properties (electronic conductivity, temperature and composition dependences of conductivity and activation energy) of lithium lanthanate and the solid solutions in the LiLaO2-Li2ZrO3 system. Conduction in LiLaO2 is likely due to lithium ion transport through a polyhedral network.

Study of ion transport in Li2ZrO3 solid electrolytes with different lithium isotope ratios

Lithium ionic conductivity and spin-lattice relaxation rates were measured in Li2ZrO3 solid electrolytes with different 6Li and 7Li ratios. It is found that single-isotope electrolytes undergo a transition to the superionic state in the temperature range of 430–450 K, accompanied by an abrupt increase in conductivity. As a result of introduction of the other type of the isotope, the conductivity jump disappears in this temperature range. The transition to the superionic state is attributed to the redistribution of lithium ions over energetically nonequivalent lattice sites.

Ionic conductivity of Li 8 − 2 x Sr x ZrO 6

Li8 − 2xSrxZrO6 solid solutions have been synthesized, and their transport properties (electronic conductivity, temperature and composition dependences of their conductivity, and activation energy for conduction) have been studied using impedance spectroscopy. The results demonstrate that partial strontium substitution for lithium increases the conductivity of the materials relative to undoped Li8ZrO6.

Investigation of ion transport in Li8ZrO6 and Li6Zr2O7 solid electrolytes

Lithium ionic conductivity and spin-lattice relaxation rates were measured in Li8ZrO6 and Li6Zr2O7 solid electrolytes. It was found that the Li8ZrO6 solid electrolyte undergoes a transition to the superionic state in the temperature range 673–703 K. It was shown that Li+ ions are mobile in particular lattice positions of the Li6Zr2O7 phase, and that ionic conductivity is monotonic at an activation energy of 79.4 kJ/mol.

Synthesis and electrochemical properties of Li8 − xZr1 − xNbxO6 solid solutions

New lithium-conducting solid solutions based on lithium orthozirconate have been synthesized by mutual doping of the related structures Li8ZrO6 and Li7NbO6. The main factor determining the increase in the electrical conductivity of the Li8 − xZr1 − xNbxO6 solid solutions is the formation of lithium vacancies in the tetrahedral and octahedral layers. The practical stability of the Li8 − xZr1 − xNbxO6 ceramics to metallic lithium has been studied.

Electrochemical properties of solid solutions in the Li8Zr1 − xCexO6 system

Li8Zr1 − xCexO6 solid solutions based on lithium zirconate Li8ZrO6 were obtained by solid-state synthesis in an inert atmosphere. Their transport properties (the electron component of the total conductivity, the temperature and concentration dependences of conductivity, and the activation energies) were studied by impedance spectroscopy. The practical stability of the ceramic samples of Li8Zr1 − xCexO6 solid solutions (x = 0–0.07) at 473–573 K against melted lithium was studied.

Ionic conduction of Li8 − 2x Mg x ZrO6 solid solutions

A boundary of existence of solid solutions in the Li8−2xMgxZrO6 system is found to be 7 mol % MgO. The transport properties of Li8 − 2xMgxZrO6 solid solutions (the electronic component of total conductivity, the temperature and concentration dependences of conductivity and activation energy) are studied. It is supposed that, for Li8ZrO6 phase and solid solution based on it, an abrupt change of conductivity in the temperature range from 663 to 713 K is caused by the transition of electrolyte into the superionic state.

Ionic conduction of Li8 − 2xMgxZrO6 solid solutions

A boundary of existence of solid solutions in the Li8−2xMgxZrO6 system is found to be 7 mol % MgO. The transport properties of Li8 − 2xMgxZrO6 solid solutions (the electronic component of total conductivity, the temperature and concentration dependences of conductivity and activation energy) are studied. It is supposed that, for Li8ZrO6 phase and solid solution based on it, an abrupt change of conductivity in the temperature range from 663 to 713 K is caused by the transition of electrolyte into the superionic state.

Effect of substituting6Li for7Li on ionic conductivity of α-Li3BO3

The ionic conductivity of γ-Li3BO3 is measured in wide intervals of temperatures and7Li to6Li ratios. It is found that the conductivity and activation energy vary nonmonotonically with variations in concentrations of the two isotopes; the concentration dependence of electroconductivity has a minimum, and that of the activation energy has a maximum at a7Li :6Li ratio of about 50 : 50 at. %; and the activation energy for conduction by6Li exceeds that by7Li