Synthesis and Electrical Properties of New Lead‐free (100−x)(Li0.12Na0.88)NbO3–xBaTiO3 (0 ≤ x ≤ 40) Piezoelectric Ceramics

Abstract

New lead‐free (100−x)Li0.12Na0.88NbO3‐xBaTiO3 (0 ≤ x ≤ 40) piezoelectric ceramics have been synthesized using conventional ceramics processing route. Structural analysis revealed an existence of morphotropic phase boundary (MPB), separating orthorhombic and tetragonal phases, between the BaTiO3 content, x = 10–12.5. A partial phase diagram has been established based on temperature‐dependent permittivity data for this new system and a almost vertical temperature‐independent MPB is observed. Improvement in electrical properties near MPB (e.g., for x = 12.5; εr = 8842 at Tm and 795 at room temperature, d33 = 30 pC/N, kp = 12.0%, Qm = 162, Pr = 11.2 μC/cm2, Ec = 19.2 kV/cm, = 174 pm/V) is observed, and is attributed to the ease of polarization rotation due to coexistence of orthorhombic and tetragonal phases. The results show that these materials could be suitable for piezoelectric vibrators and ultrasonic transducer applications. The sample with x = 25, also exhibited high dielectric permittivity, εr = 2400, and low dielectric loss, tanδ = 0.033 at room temperature which could be suitable for capacitor (X7R/Z5U) applications.