Amorphous piezo- and pyroelectric phases of BaZrO₃ and SrTiO₃

Amorphous piezo and pyroelectric phases of BaZr₃ and SrTiO ₃ can form quasiamorphous phases although neither of them have a polar crystalline polymorph. Amorphous films of SrTiO₃ or BaZrO ₃ (50- 200 nm thick) were deposited by radiofrequency magnetron sputtering on highly conductive Si substrates. The as-deposited amorphous films were then pulled through a temperature gradient in order to induce a strong inhomogeneous stress that could align the local bonding units. Stoichiometry of all samples was verified with X-ray photoelectron spectroscopy before and after heat treatment. These findings are the first instance of successful manipulation of local bonding units to obtain a noncrystalline inorganic solid with desired properties. Though qualitative, this method is highly reliable because the influences of electrical interferences, friction-induced electricity, and electrostriction can easily be excluded.