Dielectric and microstructural properties of barium titanate zirconate thin films on copper substrates

Abstract

Barium titanate zirconate, Ba(Ti 1−x Zr x )O 3 (0 ഛ x ഛ 0.25), thin films were deposited via the chemical solution deposition (CSD) method directly on copper foils. The films were processed in a reductive atmosphere containing nitrogen, water vapor, and hydrogen gas at 900°C to preserve the metallic copper substrate during crystallization. Increasing the fraction of BaZrO 3 revealed several effects, including an increase in unit cell dimensions, a decrease in both the temperature and value of the maximum permittivity, as well as a decrease in the average grain size of the films. The decrease in the relative permittivity was attributed to a grain size effect as opposed to zirconium substitution. In film compositions containing 25 mol% BaZrO 3 , the permittivity below T max became dispersive, and the ferroelectric transitions became increasingly diffuse. These characteristics suggest relaxor-like behavior. The dielectric tunability of Ba(Ti 1−x Zr x )O 3 was studied at room temperature and at T max for each composition. There was little variation in the tunability with measurement temperature; however compositions that were ferroelectric at room temperature saw a decrease in hysteresis at T max , and all compositions showed an increase in permittivity.

Enhanced Dielectric and Crystalline Properties in Ferroelectric Barium Titanate Thin Films

“…Figure 7 shows a plot of the relative permittivity at 20°C as a function of average grain size for the two bulk ceramic studies of Frey et al [3] and Arlt et al, [1] the three thin-film studies of Ihlefeld et al, [25] Waser, [26] and Parker et al, [27] and the current work. The author's previous study of barium titanate thin films on copper substrates shows enhanced permittivities over films grown on traditional substrates with equivalent grain sizes.…”

“…For the survey scans a Average Grain Diameter (nm) Figure 7. Relative permittivity at 20°C plotted vs. the average grain diameter for films from this work and those from the literature (adapted from Ihlefeld et al [25], Parker et al [27], Waser [26], Arlt et al [1], and Frey et al [3].…”

“…The author's previous study of barium titanate thin films on copper substrates shows enhanced permittivities over films grown on traditional substrates with equivalent grain sizes. [25] This was explained by improved crystallinity concomitant with the higher thermal budgets. Comparison of this previous work with results for a fluxed system identifies even more dramatic property enhancements.…”

Ferroelectric behavior in nominally relaxor lead lanthanum zirconate titanate thin films prepared by chemical solution deposition on copper foil

“…5͒ with identical composition, where the maximum in permittivity ranges from 353 to 391 K, it is clear that T C is shifted upward by 74-110 K for PLZT ͑10/ 65/ 35͒ thin films on copper. It should be pointed out in considering this mechanism, however, that the temperature at which peak permittivity occurs has not been found to be shifted for BaTiO 3 thin films on copper foil, 18 although stress development and the resulting electromechanical response are expected to be similar. This seeming inconsistency between PLZT and BaTiO 3 remains to be investigated, although differences in microstructure and internal stress distribution between the PLZT and BaTiO 3 films are likely.…”

Continuous BaTi1−yZryO3 (0≤y≤1) nanocrystals synthesis in supercritical fluids for nanostructured lead-free ferroelectric ceramics

“…The sharp ferroelectric to paraelectric phase transition for y ≤ 0.15 becomes broader increasing the substitution rate from 0.15 up to 0.25. A further increase up to 0.40 leads to a relaxor behaviour characterized by a frequency dependent dielectric permittivity maximum [1][2][3][4][5][6][7]. Such a material with a ferroelectric-relaxor crossover, exhibiting thus tunable dielectric behaviour, presents a high potential in terms of applications.…”