Dielectric measurements indicate that triammonium hydrogen diselenate (NH 4 ) 3 H(SeO 4 ) 2 has phase transitions at -8°C and -92°C. A λ-type maximum of dielectric constant along the c -axis was found at -92°C. Below the transition the compound is ferroelectric with the saturated spontaneous polarization of about 1.4 µC cm -2 .
M. KamounManel HalouaniA. Daoud
Toshiki KishimotoToshio ÔsakaM. KomukaeYasuharu Makita