Abstract
Pure K0.5Na0.5NbO3 (KNN) and KNN doped with Li+ (6% mole), La3+(1.66%, 5%, 6% mole), and Ti4+ (10% mole) were prepared by mixture of oxides using high-energy milling and conventional solid-state reaction. The effects of the dopant on the physical properties of pure KNN have been evaluated based on the structural, ferroelectric, pyroelectric, and dielectric measurements. The XRD measurements show that KNN pure sample contains a mixture of monoclinic and orthorhombic crystalline phases, with a slightly higher concentration of monoclinic phase. In contrast, all doped samples show a higher concentration of the orthorhombic phase, as well as the presence of a secondary phase (K6Nb10.8O30), also detected by Raman measurements. The samples with a higher concentration of this secondary phase, also present greater dielectric losses and lower values of remnant polarization. The dielectric measurements allowed us to detect temperatures of structural transitions (orthorhombic-tetragonal, O-T) previous to the ferroelectric-paraelectric transition (tetragonal-cubic, T-C), and also in this set of samples, a direct correlation was found between the values of remnant polarization and the corresponding pyroelectric signal response.
Highlights
Lead-free ceramic systems such as BNT, BT, BCZT, and KNN have become attractive materials for a wide range of applications in the area of electroceramics [1,2,3], due to their excellent ferroelectric, piezoelectric, and pyroelectric properties that characterize them
The two peaks located around 46° for the samples KNNLi6 and KNNLi6La1 belong to a combination of monoclinic and orthorhombic phases
We have studied the effect of Li+, La3+, and Ti4+ dopants on the structural, morphological, ferroelectric, and dielectric properties of KNN
Summary
Lead-free ceramic systems such as BNT, BT, BCZT, and KNN have become attractive materials for a wide range of applications in the area of electroceramics [1,2,3], due to their excellent ferroelectric, piezoelectric, and pyroelectric properties that characterize them. J Adv Ceram 2020, 9(3): 329–338 ratio is 50/50 [14], the KNN shows excellent ferroelectric, piezoelectric [15], pyroelectric [16], and dielectric properties [17,18,19] besides having a high ferroelectric– paraelectric transition temperature close to 420 °C, which allows its practical use in a wide range of temperature. All materials were synthesized by a combined method of high-energy milling and conventional method of reaction in solid state, using different temperatures of sintering (Table 1). The influence that these dopants cause in the structural, electrical, dielectric, and pyroelectric properties of KNN is analyzed
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call