Pyroelectric Response in Transparent Ferroelectric Glass‐Ceramics

When the network system is limited, most ferroelectric glass‐ceramics will produce a fully crystallized transparent body when cerammed at low temperatures. Higher‐temperature heat treatment results in crystal growth and gradual loss of transparency. In the transparent state, the crystal size is limited to ∼2000 Å. Piezoelectric and hysteresis loop measurements have failed to detect evidence of ferroelectricity, but the present pyroelectric measurements show that fully transparent glass‐ceramics can be ferroelectric.