Abstract
We have investigated the dielectric characteristics at microwave frequencies of perovskites with the formula (A1/21+·A1/23+)TiO3, (where A1+ represents an alkali metal from the lithium to potassium series and A3+ represents a member of the lanthanide series from lanthanum to lutetium). It was found for the first time that in the case of Li1+ substitution at the A1+ site, the larger the ionic radius of the element which substituted at the A3+ site, the higher the dielectric constant was and the greater the negative shift of the temperature coefficient of resonant frequency was. For the (1-x)(Li1/21+·Sm1/23+)TiO3-x(Na1/21+·Sm1/23+)TiO3 system at 3 GHz, high dielectric properties of εr=81, Q=2050 and τf=+17ppm/ °C were obtained when x=0.4.