The giant dielectric constant and tunable properties of La2NiMnO6-xMgO ceramics

Effect of MgO addition on the microstructure, electrical and dielectric properties of La2NiMnO6 ceramics was investigated. Trace amount of Mg2+ substituted Ni ion. After exceeding the limit of solubility, MgO segregated as an independent phase on the grain boundary and suppressed grain growth. Electrode response dominated impedance of La2NiMnO6-xMgO ceramics around room temperature. Two dielectric relaxations originated from electrode and grain boundary effects have been revealed, which resulted in the giant dielectric constant of La2NiMnO6-xMgO ceramics. The addition of MgO suppressed dielectric constant and loss. The electrode effect caused the sizable dielectric tunability at high temperature and low frequency range. The addition of MgO increased electrode response of La2NiMnO6-xMgO around room temperature and enhanced the tunability.