Fabrication of (100)_c-oriented Mn-doped bismuth ferrite films on silicon and stainless steel substrates using calcium niobate nanosheets

Abstract

One-axis-oriented BiFeO 3 (BFO)-based films were fabricated on platinized silicon and SUS 316L substrates using nanosheets of calcium niobate (ns-CN) with pseudo-perovskite crystal structure. Ca 2 Nb 3 O 10 nanosheets (ns-CNs) were supported on the substrates by dip coating, followed by chemical solution deposition (CSD) of Mn-doped BFO (Mn-BFO) films. Preferential crystal growth of (100)-oriented BFO films was achieved on both ns-CN/(111)Pt/TiO 2 /(100)Si and ns-CN/(111)Pt/SUS316L substrates. The out-of-plane lattice parameters of the BFO films on ns-CN/(111)Pt/SUS316L were larger than the parameter reported for BFO bulk because of elastic deformation caused by thermal stress between the BFO films and SUS316L substrate, whereas those of the films on ns-CN/(111)Pt/TiO 2 /(100)Si were smaller than the reported value. The remanent polarization of the Mn-BFO films was enhanced to approximately 60¯C/cm 2 on ns-CN/(111)Pt/SUS316L because of the compressive thermal stress that causes elastic elongation of Mn-BFO crystals to align or change the tilt angle of their polar axes for the substrate surface.

Orientation control of barium titanate films using metal oxide nanosheet layer

“…1. However, it required heat treatment (i.e., crystallization) at temperatures higher than 800 °C, which was essentially different from the results for other perovskite-based films such as Pb(Zr,Ti)O 3 , BiFeO 3 , or layered-perovskites [29][30][31][32] in which the preferred crystal growth proceeded even at lower crystallization temperatures. In the present case for BaTiO 3 , low-temperature treatment yielded a polycrystalline structure with a random crystalline orientation and insufficient grain growth.…”

“…23,24) Recently, single-crystal nanosheets of metal oxides have been focused as the buffer layers for preferred crystal orientation [25][26][27] because they can be easily synthesized and then supported on the ubiquitous substrates via a series of simple processes using aqueous solutions at room temperature. [27][28][29] Our group has also reported the preferred crystal orientation of Pb(Zr,Ti)O 3 29,30) and BiFeO 3 , 31) as well as bismuth layer-structured CaBi 4 -Ti 4 O 15 dielectrics, 32) and their dielectric and ferroelectric dependence on crystal orientation and in-plane thermal stress.…”

Polarization switching behavior of one-axis-oriented lead zirconate titanate films fabricated on metal oxide nanosheet layer

“…Platinized silicon substrates with ns-CN template layer (ns-CN=Pt=Si) were prepared by the dip coating method, similarly to that in previous reports. [27][28][29][30][31] The size of the substrates was ∼10.0 × 5.0 mm 2 .…”

“…[24][25][26][27] One major advantage of the ns-CN template is that it can be applied to various substrates, including the ubiquitous substrates for device fabrication at room temperature, independent of the crystallographic configuration of the substrate surface. The template layer of ns-CN aided the preferential crystal growth of some simple-perovskite oxides (SrTiO 3 , BaTiO 3 , BiFeO 3 , and LaNiO 3 ) 24,26,28,29) as well as a layered-perovskite compound (CaBi 4 Ti 4 O 15 ) 27) on ubiquitous substrates of Si wafer, glass, and stainless steel. As for the crystal growth of PZT, we have confirmed the preferential crystal growth of tetragonal PZT(001) or (100) films, controlled by in-plane thermal stress, up to the thickness of 300 nm, as well as the enhancement or degradation of their ferroelectric property depending on the crystal orientation.…”

One-axis-oriented growth of PZT thin films on transparent glass substrates using metal oxide nanosheets

“…Nanosheets of calcium niobate (Ca 2 Nb 3 O 10 ; ns-CN) with a pseudo-perovskite-type crystal structure (lattice parameters: a = b = 0.386 nm) exhibit favorable lattice matching with various kinds of ferroelectric materials such as PZT, LNO, SrTiO 3 , BaTiO 3 , and BiFeO 3 , which promotes preferential crystal growth. [22][23][24][25][26][27][28][29][30] We previously reported the deposition of polar-axis-oriented PZT thin films by introducing an ns-CN buffer layer on the surface of ubiquitous substrates such as Si wafers and Inconel alloys. 26,27) A nanosheet buffer layer, such as an ns-CN, can be formed without high-temperature heating, which is a problem for the preferential crystal growth of PZT thin films on glass substrates.…”