Doping effect of SrZrO3 on KNLN ceramics structure and their dielectric properties

Abstract

In this work, lead-free systems; (1−x) (K0.465Na0.465Li0.07) NbO3–xSrZrO3 (x=0, 0.005, 0.050, 0.095 and 0.14) were synthesized by the conventional solid-state reaction technique. XRD, SEM, densification parameter as well as dielectric parameters of the obtained KNLN ceramics were investigated. XRD analysis showed the formation of orthorhombic perovskite structure in all investigated specimens. SrZrO3 (SZ) inhibited the grain growth and increased the distribution of grains uniformly in the microstructure. In addition, SZ changed the crystalline system of KNLN ceramics abnormally. As a consequence, the permittivity, dielectric loss as well as AC conductivity decreased remarkably. The ceramics of x=0.005 are characterized by low conductivity (10−10S/cm), low dielectric loss (0.005) and relatively high permittivity (34). They can be useful for the electrical capacitors fabrication and filtering out noise from signals in resonant circuits. At frequencies lower than 105Hz, DC conductivity and separation of the charges at the interfaces were found to dominate the electrical behavior of ceramics, whereas at higher frequencies, a faster or dipole polarization may become more dominated. A broad peak has been observed in the imaginary part of electric modulus revealing to the non-Debye dielectric relaxation behavior. Quantum mechanical tunneling (QMT) was found to be the most suitable to characterize the electrical conduction mechanism in the ceramic compounds.

Keywords

• Lead-free ceramics
• KNLN
• dielectric properties