Glossary
315
complex number whose modulus is the ratio of the amplitude of the applied
voltage to the resulting current, and whose argument is given by the phase
difference between the current and the voltage.
Intensiostatic (galvanostatic) mode – A technique for plotting the characteristic
potential/current of an electrode. In intensiostatic mode, a constant current
is imposed on the working electrode and we measure the potential with respect
to a reference electrode.
Ionic conductivity – The conductivity due to ionic species (cations, anions) present
in a material. In an aqueous medium, an organic medium, and molten salts,
cations and anions contribute to the electric current. In solid-state electrolytes, the conductivity is primarily due to a single ionic species (cationic or
anionic). In the solid phase, we associate the displacement of ions to a given
mechanism (vacancy, interstitial, ...). For example, in yttria-stabilized zirconia
(YSZ), the ionic conductivity is due to oxide ions O
2–
following a vacancy
mechanism. In sodium chloride NaCl, the species Na
+
is responsible for
the ionic transport following a vacancy mechanism. Finally, note that ionic
conductivity is an activated phenomenon.
Insertion material – An electrode material into which, through a chemical or
electrochemical reaction, ions can be inserted. This property results from
the particular crystalline structure of the material, which contains empty
sites that can host an insertion species. Insertion materials are generally solid
solutions of transition-metal oxides. They must have a mixed conductivity
with a non-negligible ionic contribution to the conductivity. The insertion
reaction is a delocalized reaction that occurs throughout the bulk of the material. Over the last decades, lithium- and proton-insertion materials have
received the most attention for research and development. Two examples
are LiMn 2 O 4 and V 2 O 5 .
Interstitial position – An atom is said to occupy an interstitial position when it
occupies a site that is normally empty in the ideal structure.
Intrinsic defect – A structure defect that is due to thermal agitation in a pure ionic
crystal. Intrinsic defects often come in pairs. For example, in silver chloride
AgCl, intrinsic defects are silver vacancies and interstitial silver cations Ag
+
.
Kröger-Vink notation – A notation used in solid-state chemistry and solid-state electrochemistry. It is used to identify the chemical species and filling anomalies
in a crystal (vacancies, interstitial ions, …). This notation clearly identifies,
for a given ion, the site it occupies, the chemical nature of the ion, and its
effective charge. For example, O
•
F refers to an oxide ion with a positive effective charge occupying the site of a fluorine ion.
315
complex number whose modulus is the ratio of the amplitude of the applied
voltage to the resulting current, and whose argument is given by the phase
difference between the current and the voltage.
Intensiostatic (galvanostatic) mode – A technique for plotting the characteristic
potential/current of an electrode. In intensiostatic mode, a constant current
is imposed on the working electrode and we measure the potential with respect
to a reference electrode.
Ionic conductivity – The conductivity due to ionic species (cations, anions) present
in a material. In an aqueous medium, an organic medium, and molten salts,
cations and anions contribute to the electric current. In solid-state electrolytes, the conductivity is primarily due to a single ionic species (cationic or
anionic). In the solid phase, we associate the displacement of ions to a given
mechanism (vacancy, interstitial, ...). For example, in yttria-stabilized zirconia
(YSZ), the ionic conductivity is due to oxide ions O
2–
following a vacancy
mechanism. In sodium chloride NaCl, the species Na
+
is responsible for
the ionic transport following a vacancy mechanism. Finally, note that ionic
conductivity is an activated phenomenon.
Insertion material – An electrode material into which, through a chemical or
electrochemical reaction, ions can be inserted. This property results from
the particular crystalline structure of the material, which contains empty
sites that can host an insertion species. Insertion materials are generally solid
solutions of transition-metal oxides. They must have a mixed conductivity
with a non-negligible ionic contribution to the conductivity. The insertion
reaction is a delocalized reaction that occurs throughout the bulk of the material. Over the last decades, lithium- and proton-insertion materials have
received the most attention for research and development. Two examples
are LiMn 2 O 4 and V 2 O 5 .
Interstitial position – An atom is said to occupy an interstitial position when it
occupies a site that is normally empty in the ideal structure.
Intrinsic defect – A structure defect that is due to thermal agitation in a pure ionic
crystal. Intrinsic defects often come in pairs. For example, in silver chloride
AgCl, intrinsic defects are silver vacancies and interstitial silver cations Ag
+
.
Kröger-Vink notation – A notation used in solid-state chemistry and solid-state electrochemistry. It is used to identify the chemical species and filling anomalies
in a crystal (vacancies, interstitial ions, …). This notation clearly identifies,
for a given ion, the site it occupies, the chemical nature of the ion, and its
effective charge. For example, O
•
F refers to an oxide ion with a positive effective charge occupying the site of a fluorine ion.