Effects of deposition temperature on characteristics of ferroelectric Sr₂Bi₄Ti₅O₁₈nanoplates fabricated by RF sputtering

Abstract

Sr 2 Bi 4 Ti 5 O 18 (SBTO) films with a-and b-axis orientations, and thicknesses of 0.9-1.2 µm were sputter-deposited on conductive Nb:TiO 2 (101) substrates containing 0.79 mass % Nb. The deposition temperature was varied from 575 to 700 °C under a fixed gas pressure of 0.4 Pa, and the structural and ferroelectric characteristics of the films were investigated. SBTO films deposited at 625-700 °C had a mostly single-phase orthorhombic structure, with a high degree of a-and b-axis orientations [α (h00)/(0k0) ] of 99.0-99.8%. In addition, the full width at half maximum of the (200) diffraction peak was 0.69-0.86°, which indicated good crystallinity. SBTO films deposited at 625-650 °C had a nanoplate-like microstructure with the plates aligned along the [010] direction. The real room-temperature remanent polarization ð2P Ã r Þ, taking the porosity between the nanoplates into account, exhibited a maximum of 40 µC/cm 2 at 650 °C. Thus, the optimal deposition temperature for heteroepitaxial growth of SBTO nanoplates with a high α (h00)/(0k0) of ;99.0% and excellent ferroelectric properties on conductive Nb:TiO 2 substrates is 650 °C under a gas pressure of 0.4 Pa.

Fabrication and physical properties of bismuth layer-structured ferroelectric thin films with c-axis orientation epitaxially grown by high-temperature sputtering

“…This suggests that re-evaporation of Bi 2 O 3 from the sputtered film surface increases with increasing substrate temperature. 21) Figure 4 shows the variations in the lattice parameter (c-axis length) and unit cell volume for BNEuT films deposited at 580 °C-650 °C. The lattice parameter and the unit cell volume decrease almost linearly with increasing substrate temperature.…”

“…α (00l) was calculated by a method similar to that previously reported. [1][2][3]21,22) To determine the out-of-plane and in-plane lattice parameters (a, b, and c), XRD reciprocal space mapping measurements were carried out using a high-resolution XRD system (Rigaku SmartLab) with Cu Kα radiation. Their parameters were calculated using the reciprocal lattice points of BNEuT (0028), (4028), and (0428) (not shown).…”

Effects of sputtering gas pressure on physical properties of ferroelectric (Bi3.25Nd0.65Eu0.10)Ti3O12nanoplate films

“…The degree of a-and b-axis orientations α (h00)=(0k0) was calculated by a method similar to that previously reported. 7,8,21,22) To determine the out-of-plane and in-plane lattice parameters ða; b; cÞ, XRD reciprocal space mapping (XRD-RSM) was carried out in a highresolution XRD system (Rigaku SmartLab) using Cu Kα radiation. The orthorhombicity was calculated using the expression 2(a − b)=(a + b).…”

Fabrication and characterization of micropillar-type multiferroic composite thin films by non-aqueous sol-gel method using ferroelectric pillars

“…In our previous studies, we fabricated (Bi 3.25 Nd 0.65 Eu 0.10 )Ti 3 O 12 (BNEuT) nanoplate thin films with a strong a-axis orientation on conductive single-crystal Nb:TiO 2 (101) substrates by high-temperature sputtering. [17][18][19][20][21][22][23] On the basis of that the BNEuT films exhibit a large room-temperature remanent polarization (2P r = 66 μC cm −2 ) which is comparable to that of Pb(Zr,Ti)O 3 for practical use, we use BNEuT as a ferroelectric material in this study. In addition, It is known that CFO synthesis in pillar-type MFs is generally carried out by PLD, [12][13][14] high-temperature sputtering, 15) and electrochemical deposition.…”