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Technology and Dielectric Properties of the KNLN Doped with Nd3+ and Pr3+ Ions

Bochenek D., Osińska K., Mankiewicz M., Niemiec P., Dercz G.

Archives of Metallurgy and Materials

2020

Vol. 65, iss. 3

1183--1188

The paper presents the technology and basic properties of three compositions of lead-free ceramics: (i) (K0.44Na0.52Li0.04)NbO3, (ii) (K0.44Na0.52Li0.04)NbO3)NbO3 +0.5%mol Nd2O3 and (iii) (K0.44Na0.52Li0.04)NbO3)NbO2+0.5%mol Pr2O3. Powders of the designed compositions based on KNLN were obtained with the classic ceramic technology, as a result of solid phase synthesis, from a mixture of simple oxides and carbonates. The synthesis of ceramic powders was carried out at Ts = 900°C for ts = 4 h, while compaction by free sintering at Tsint = 1100°C for tsint = 2 h. XRD studies have shown that doping with praseodymium and neodymium promotes the formation of the tetragonal phase in the base composition (K0.44Na0.52Li0.04)NbO3)NbO3 at lower temperatures. On the other hand, microstructural tests have shown that the admixture of neodymium and praseodymium improves the sinterability of ceramic samples during the technological process; however, the ceramic samples still exhibit high porosity.

Technology and Electrophysical Properties of the (K0.44Na0.52Li0.04)NbO3 Ceramics Doped by Cr3+, Zn2+, Sb3+ or Fe3+

Bochenek D., Osińska K., Niemiec P., Adamczyk M., Goryczka T., Szych R.

Archives of Metallurgy and Materials

2018

Vol. 63, iss. 3

1401--1409

In the work five ceramic compounds based on the (K0.44Na0.52Li0.04)NbO3 (KNLN) material modified with oxides: Cr2O3, ZnO, Sb2O3 or Fe2O3 (in an amount of 0.5 mol.%) were obtained. The KNLN-type composition powder was prepared by solid phase synthesis from a mixture of simple oxides and carbonates, while compacted of the ceramic samples was conducted by free sintering methods. In the work the effect of the used admixture on the electrophysical properties of the KNLN ceramics was presented. The XRD, EDS tests, the SEM measurements of the morphology ceramic samples, dielectric properties and DC electric conductivity were conducted. The research showed that the used admixtures introduced into the base of KNLN-type composition improve the microstructure of the ceramic samples and improve their sinterability. In the case of the dielectric measurements, it was observed a decrease in the maximum dielectric permittivity at the TC for dopred KNLN-type samples. The addition of an admixture of chromium, zinc, antimony or iron in an amount of 0.5 mol.% to the base composition (K0.44Na0.52Li0.04)NbO3 practically does not change the phase transition temperature. The diminution in the density value of doped KNLN ceramics was attributed to the alkali elements volatilization.