Structure and microwave dielectric properties of Sm_(2−x)/3Li _x TiO₃

Abstract

The structural evolution, and microwave dielectric properties of ${\text{Sm}}_{{{{\left( {2 - x} \right)}} \mathord{\left/ {\vphantom {{{\left( {2 - x} \right)}} 3}} \right. \kern-\nulldelimiterspace} 3}} {\text{Li}}_{x} {\text{TiO}}_{3}$ ceramics (x = 0.0 ≤ x ≤ 0.5) were investigated in this work. X-ray diffraction (XRD) results show that samples with x > 0.3 exhibit a single perovskite phase. Impurity phases of Sm₂Ti₂O₇ and TiO₂ appear and their amount increases with the decrease of x when x ≤ 0.3. TEM observation indicates that the A-site is ordered in x = 0.5, but not in x = 0.3). The dielectric constant decreases with the increase of x for 0.1 ≤ x ≤ 0.4 and then increases with further increase in x up to x = 0.5. The Q×f value decreases with the decrease of x due to the increased occurrence of Sm₂T₂O₇ secondary phase, defects and twinning boundaries. The temperature coefficient of resonant frequency is negative and its absolute value decreases greatly with the decrease of x value.