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

The structural evolution, and microwave dielectric properties of Sm _{(2 - x)/3}Li_xTiO₃ 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 Sm₂Ti₂O ₇ 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.