Sol–Gel Synthesis and Characterization of Na_0.5Bi_0.5TiO₃–NaTaO₃Thin Films

Abstract

Thin films with the composition 70 mol% Na0.5Bi0.5TiO3 + 30 mol% NaTaO3 were prepared by sol–gel synthesis and spin coating. The influence of the annealing temperature on the microstructural development and its further influence on the dielectric properties in the low‐ (kHz–MHz) and microwave‐frequency (15 GHz) ranges were investigated. In the low‐frequency range we observed that with an increasing annealing temperature from 550°C to 650°C the average grain size increased from 90 to 170 nm, which led to an increase in the dielectric permittivity from 130 to 240. The temperature‐stable dielectric properties were measured for thin films annealed at 650°C in the temperature range between −25°C and 150°C. The thin films deposited on corundum substrates had a lower average grain size than those on Si/SiO2/TiO2/Pt substrates. The highest average grain size of 130 nm was obtained for a thin film annealed at 600°C, which displayed a dielectric permittivity of 130, measured at 15 GHz.

Red-orange photoluminescence and dielectric relaxation of Eu3+-doped Bi2Ti2O7 pyrochlore structure thin films

“…Similar values are reported in other rare-earth doped Bi 2 Ti 2 O 7 thin films [9]. The dielectric relaxation of the Eu 3þ -doped Bi 2 Ti 2 O 7 pyrochlore thin films is possibly due to the composition fluctuation of the cations occupied on the A sites in pyrochlore structure A 2 B 2 O 6 O 0 as well as the difference in structure defects [28,29], whereas the photoluminescence of our thin films originates from the 4f-4f transitions of Eu 3þ ions under UV excitation. The composition fluctuation and defect would possibly influence the PL intensity of Eu 3þ ions.…”

Preparation of the NaTaO₃ Crystal from the KTaO₃ Substrate via Topotactic Alkaline Cation Substitution as Confirmed by Transmission Electron Microscopy

“…However, usual catalysis studies have been performed with NaTaO 3 powder samples, and it prevented the fine bulk and surface characterization. In order to approach and reveal the basic mechanism of bulk and surface reactions of the NaTaO 3 material, film and substrate preparations by the hydrothermal reaction [8−11], the sol-gel synthesis [12,13], the flux synthesis [14,15], and any other deposition methods [16−19] have been studied. However, prepared films by these methods were consisted to be polycrystalline NaTaO 3 crystals with complex orientation so that it was not suitable for detailed investigations of the bulk and surfaces of NaTaO 3 .…”

Экспериментальное исследование и ab initio расчет свойств Sc-, In-допированных титанатов висмута со структурой типа пирохлора

“…Так, с использованием реакции твердофазного синтеза были получены термо-стабильные титанаты висмута со структурой пирохлора, допированные атомами Cr, Mn, Fe, Cu, Zn, Y и Nd, и изучены их электрофизические свойства [5,6,[18][19][20][21][22][23][24][25].…”