Abstract:

Lithium-modified potassium sodium niobate/copper (NKLN/Cu) piezoelectric composites were fabricated by protective sintering in a industrial nitrogen gas. The phase structure, density, electrical and mechanical properties were studied in relation to Cu content. The results show that the composites consists of  only NKLN and Cu phases,  the relative densities of the composites were all above 95% theoretic densities. The relative dielectric constant  r of the composites markedly increased with increasing Cu concentration. The piezoelectric constant d₃₃ and electromechanical coupling factor kp decreased as the volume of Cu was increases. When increasing Cu concentration up to 20%, the  r, d₃₃ and kp were hard to detect. The microhardness of the composites decreased with the addition of Cu. With increasing Cu content up to 40%, the fracture toughness KIC gradually increased from 1.01 MPa for monolithic NKLN ceramics to 2.81 MPa for NKLN-40%Cu composite.

Key words: materials synthesis and processing technology, NKLN/Cu, piezoelectric composites,  , electrical properties,  , fracture toughness