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Dielectric loss of glass

When glass is used as a dielectric, due to the effect of the AC electric field, it will convert part of the electrical energy into heat energy due to polarization or absorption and loss.

The dielectric loss of glass is caused by ion polarization, molecular polarization and space charge polarization caused by electron displacement and ion displacement. Therefore, the dielectric loss is large for any small volume resistivity; when the temperature rises, the dielectric loss tangent tgδ value also increases due to the decrease in volume resistivity.

The dielectric loss of glass is also determined by its chemical composition. Any component that can increase the conductivity of glass will increase the dielectric loss. Therefore, glass containing a large amount of alkali metal oxides (especially NanO) has a large dielectric loss. On the contrary, divalent oxides (such as PbO, BaO, CaO, etc.) reduce dielectric loss.

As the dielectric loss increases, the viscosity of the glass decreases and the conductivity increases. Generally speaking, the safe dissipation of glass with a thickness of about 1.5mm is about 2.5W/cm². Therefore, it is not advisable to let glass work at high frequency and high temperature.

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