Electrical and microstructural properties of CaTiO 3 -doped K 1/2 Na 1/2 NbO 3 -lead free ceramics

Abstract

Abstract. Microstructure, electrical properties and dielectric behaviour of K 1/2 Na 1/2 NbO 3 (KNN) and CaTiO 3 -modified K 1/2 Na 1/2 NbO 3 (CTO-KNN) systems, were investigated. Discs doped with 0 to 0·55% mol of CaTiO 3 (CTO) were sintered at 1125 • C for 2 h. Although minority phases were found in doped samples, CaTiO 3 was not detected. It was also observed that CTO changed the microstructure and grain size of KNN drastically. Also, the Curie temperature and permittivity values decreased. Addition of CTO between 0·15 and 0·45 mol% decreases the density and dielectric values. Samples prepared with higher content of CTO than 0·45 mol% showed better electrical properties.

Low‐Temperature Sintering and Piezoelectric Properties of CuO‐Added KNbO3 Ceramics

“…Therefore, it is very difficult to obtain dense NKN ceramics with homogeneous composition and reliable piezoelectric properties. To overcome this problem and improve the piezoelectric properties, many investigations have been conducted on NKN‐based solid solutions . In particular, (1 − x )NKN‐ x Li 2 O(Nb, Ta, Sb) solid solutions have been studied extensively because of their promising piezoelectric properties .…”

Efecto del BiFeO₃ en las propiedades del sistema ferroeléctrico libre de plomo K_0.5Na_0.5NbO₃

“…El KNN puro experimenta dos transiciones de fase por encima de la temperatura ambiente; la primera transición, de ortorrómbica a tetragonal (T O-T ), ocurre a ∼200 ºC; la segunda, de tetragonal a cúbica (T T-C ), se presenta a ∼420 C (T C ) [33]. Algunos autores han reportado que la adición de dopantes al KNN genera una modificación en el valor de T O-T a valores cercanos a la temperatura ambiente y de T C a ∼315 ºC [34,35,36]; se ha encontrado que el dopaje puede disminuir T C hasta ∼270 ºC [37]. En estas figuras se puede también evidenciar del KNN con la inclusión del BLFO dentro de su estructura cristalina.…”

Evaluation of structure, dielectric and electrical properties of (Li/Ta/Sb) modified (Na, K) NbO3 lead-free ceramics with excess Na concentration

“…1 Among the available lead-free materials, (Na 1Àx K x ) NbO 3 (KNN) has been widely studied due to excellent electromechanical coupling, high Curie temperature and piezoelectric properties. 2 In 2004, Saito et al 3 studied the textured (K, Na) NbO 3 -LiTaO 3 -LiSbO 3 system by reactive templated grain growth (RTGG) method and were successful in achieving excellent piezoelectric coefficient value (d 33 $ 416 pC/N). It is believed that this high piezoelectric property could be achieved because of the morphotropic phase boundary (MPB) among rhombohedral, tetragonal or monoclinic phases.…”