Glass is an insulator at normal temperature, but it may exhibit a certain degree of electrical conductivity under extreme conditions.
1. At room temperature: Typical insulator
Extremely high resistivity: The resistivity of ordinary glass is approximately 10^{11} \sim 10^{14} \Omega \cdot \text{cm}10-11~ 10
fourteen
Ω⋅cm (much higher than conductors, such as copper, only 10^{-6} \Omega \cdot \text{cm}10.6 -Ω⋅cm.
Reason
In the main components of glass (such as SiO₂), electrons are bound by strong covalent bonds and are difficult to move freely.
There are no free electrons or ions (the amorphous solid structure further restricts charge migration).
2. At high temperatures: May be weakly conductive
Ionic conductivity: When heated to high temperatures (such as above 300℃), metal ions like sodium and calcium in the glass may gain sufficient energy to migrate, generating a weak current.
Application: This feature is used for some high-temperature sensors, but it can be ignored in daily environments.
3. Exceptions to special glass
Conductive glass (such as ITO glass) :
The surface is coated with indium tin oxide (ITO) film, which is conductive and transparent, and is used in touch screens and liquid crystal displays.
Metallic glass (amorphous alloy) :
Glass containing metal components, conductive, but not in the traditional sense.
4. Breakdown phenomenon
High-voltage breakdown: Glass may be broken down under extremely high voltages (such as lightning), but this is a destructive discharge and abnormal conduction.
Summary
Daily uses: Glass is an insulator and is widely used for electrical insulation, window insulation, etc.
Special scenarios: High temperature, coating or modification may cause conductivity, but specific analysis is required.
