Effects of sputtering gas pressure on physical properties of ferroelectric (Bi_3.25Nd_0.65Eu_0.10)Ti₃O₁₂nanoplate films

Abstract

Bi 3.25 Nd 0.65 Eu 0.10 )Ti 3 O 12 (BNEuT-0.1) films with a-and b-axis orientations and thicknesses of 1.8-2.3 µm were sputter-deposited on conductive Nb:TiO 2 (101) substrates containing 0.79 mass % Nb. The deposition temperature was fixed at 650 °C, and the sputtering gas pressure was varied from 0.4 to 5.0 Pa in order to examine its effect on the structural, ferroelectric and piezoelectric properties of the films. The films were found to have a mostly single-phase orthorhombic structure, with a high degree of a-and b-axis orientations (93-98%). The films had a nanoplate microstructure, with the plates being aligned along the [100]/[010] direction, and porosities of 15-25%. A maximum room-temperature remanent polarization (2P r ) of 93 µC/cm 2 was obtained for a sputtering gas pressure of 5.0 Pa. All the films were strongly a-axis oriented, according to the results of X-ray diffraction measurements and vertical amplitude images in piezoresponse force microscopy. The optimal sputtering gas pressure for heteroepitaxial growth of BNEuT-0.1 nanoplates with a high degree of a-axis orientation of 96.5%, a maximum orthorhombicity of 0.0017, a comparatively large remanent polarization of 2P r = 66 µC/cm 2 , and a high porosity of 24% was found to be 0.4 Pa.

Fabrication and leakage current and ferroelectric characteristics of multiferroic Fe3O4/(Bi3.25Nd0.65Eu0.10)Ti3O12composite thin films with Fe3O4magnetic electrodes micropatterned by reactive ion etching

“…BNEuT ferroelectric template films were deposited on (101) Nb:TiO 2 substrates using an rf sputtering equipment. [15][16][17] Fe 3 O 4 films were deposited by MOCVD using iron(III) tris (2,2,6,6-tetramethyl-3,5-heptanedionato) [Fe(thd) 3 ] 33,34) as the metalorganic precursor. The MOCVD system had a single metalorganic precursor delivery system, and has been described in detail elsewhere.…”

“…To minimize clamping effects [1][2][3] due to the presence of a substrate, and achieve enhanced multiferroic (MF) properties (ferroelectricity and ferromagnetism) and a large magnetoelectric (ME) effect, [4][5][6][7][8] we fabricated nanopillar-type MF composite devices by depositing the ferromagnetic material magnetite (Fe 3 O 4 ) [9][10][11][12][13][14] on (200) (Bi 3.25 Nd 0.65 Eu 0.10 )Ti 3 O 12 (BNEuT)=(101) Nb:TiO 2 substrates [15][16][17] by metalorganic chemical vapor deposition (MOCVD) 18,19) in our previous study. 20) We succeeded in achieving a high magnetite particle filling rate of approximately 90% in narrow spaces between BNEuT nanoplates.…”

Effects of post-annealing temperature and micropillar shape on physical properties of micropillar-type multiferroic composite thin films

“…15) In our previous study, we have successfully fabricated a-axis oriented (Bi 3.25 Nd 0.65 Eu 0.10 )Ti 3 O 12 (BNEuT) nanoplates with a unique nanoplate structure and large remanent polarization (2P r = 66 μC cm −2 ) at room temperature. [16][17][18] The MF composite films were fabricated by utilizing the gaps in the nanoplate structure, 19,20) but the ME effect could not be clearly observed due to the small amount of ferromagnetic material introduced in the small gaps. Therefore, ferroelectric micropillar structure controlled sizes of gaps were fabricated by reactive ion etching (RIE).…”

Structural, Magnetic and Electric Characteristics of Multiferroic CoFe₂O₄/BNEuT Composite Thin Films Produced by Non-aqueous Sol-gel Process

“…In our previous studies, we succeeded in achieving heteroepitaxial growth of (Bi 3.25 Nd 0.65 Eu 0.10 )Ti 3 O 12 (BNEuT) nanoplates with a strong a-axis orientation by high-temperature sputtering on conductive single-crystal Nb:TiO 2 (101) substrates containing 0.79 mass% Nb [12][13][14]. This material is promising as a ferroelectric template for fabricating nanopillar MF composite devices, since it exhibited a large room-temperature remanent polarization (2P r ) of 66 C/cm 2 and a high surface porosity of 24%.…”