Search

The epitaxial growth, structural properties, and ferroelectric properties of bismuth lanthanum nickel titanate (Bi1-xLax) (Ni0.5Ti0.5)O3 (BLNT) thin films deposited on Pt(100)/MgO(100) substrates by rf magnetron sputtering have been investigated using x-ray diffraction, transmission electron microscope, and polarization–electric field hysteresis loop measurements. The ferroelectric BLNT(00ℓ) phase with c-axis orientation and a single-phase tetragonal perovskite structure appeared at x>=0.3. The tetragonality (c/a) increased significantly from 1.004 to 1.028 with increasing La content. The fabricated BLNT films of x>=0.3 indicated the apparent fourfold rotational symmetry observed for a MgO(202) substrate, a bottom Pt(202) electrode, and a BLNT(101) ferroelectric film, based on [lowercase_phi_synonym] scan measurements. These results imply that the present La-substituted BLNT films are grown heteroepitaxially at x>=0.3. It was confirmed that Bi in the BLNT films is in a trivalent state at A sites in the perovskite crystal, based on x-ray anomalous diffraction measurements and x-ray absorption near edge structure spectra. The sputtering technique using compacted powder targets designed by taking the bond dissociation energy of metal oxides into account provided epitaxial perovskite-structured BLNT thin films on Pt(100)/MgO(100) substrates. It is shown that the c-axis oriented epitaxial BLNT film exhibits a hysteresis loop shape with a Pr value of 12 μC/cm2 that is comparable to typical high-performance Bi3.25La0.75Ti3O12 (BLT) film. [ABSTRACT FROM AUTHOR]

The 3.0-μm (Bi3.25Nd0.75)Ti3O12 (BNT-0.75) films were fabricated on IrO2(101)/ Al2O3(012) substrates by high-temperature sputtering. The XRD pole figure demonstrated that a 3.0-μm BNT-0.75 film deposited on the IrO2 electrode is grown with a strong 10° off-(100)/(010) and a weak (101)/(011) orientations of threefold symmetry. The BNT films represented random orientation near the bottom IrO2 electrode and the intermediate part of the film. In the upper part of the BNT layer, the existence of a- and b-axis-oriented rod-shaped crystals with approximately 0.25 μm width were confirmed. In contrast, the BNT film deposited directly on the Al2O3(012) substrate represented almost completely a- and b-axis orientations in a whole BNT layer. [ABSTRACT FROM AUTHOR]

Epitaxial Pb(Zr0.3Ti0.7)O3 films with different thicknesses and a preferential c-axis orientation were successfully fabricated on PbTiO3/Pt(100)/MgO(100) substrates from an amorphous state by hot isostatic pressing (HIP). Based on the results of X-ray pole figures, all the PZT films with ferroelectric layer thicknesses of 100-300 nm after HIP were almost completely epitaxial. Since the 200-nm-thick PZT film has the largest initial pulse-derived switchable polarization and an intermediate reduction rate of the three samples, its polarization fatigue characteristics are relatively superior to these of the others. From the measurements of static imprint characteristics, the observed shifts of the PZT samples apparently decreasing with decreasing film thickness. [ABSTRACT FROM AUTHOR]

The Pb(Zr, Ti)O3 and PbTiO3 precursor films formed on Pt/TiOx/SiO2/Si substrate below 400°C by metal-organic chemical-vapor-deposition (MOCVD) method were treated hydrothermally in Ba(OH)2-Pb(OH)2 mixture alkaline solution at 240°C and successfully transformed into (Pb, Ba)(Zr,Ti)O3 and (Pb, Ba)TiO3 ferroelectric thin film. This low temperature preparation method is compatible with the ULSI process becouase thermal damage to the circuit is avoidable. XRD χ - 2θ reciprocal space mapping measurements, shows that orientation of the thin film treated hydrothermally is influenced much by crystallite states of MOCVD precursor film. When the PbTiO3 precursor film is pre-crystallized having small (001) peak in XRD, the (Pb, Ba)TiO3 thin film has clear (001) orientation after hydrothermal treatment. The (Pb, Ba)TiO3 thin film treated at 240°C for 3 h in 0.2 M Ba(OH)2 - 0.1 M Pb(OH)2 solution has a hysteresis loop with good shape, and the polarization at zero electric field of the treated thin film is 8 μC/cm2. [ABSTRACT FROM AUTHOR]

Ferroelectric and piezoelectric properties of Pt/0.24Pb(Zn1/3Nb2/3)O3⋅0.384-PbZrO3⋅0.376PbTiO3 (PZNZT)/PbTiO3/Pt capacitors fabricated by crystallizing amorphous PZNZT films under high pressures of 1.0–176.5 MPa using hot isostatic pressing (HIP) are investigated. All of films HIP-treated under high pressure over 17.7 MPa hardly showed the fatigue degradation up to the switching cycles of 3× 1010. From piezomeasurements using piezoresponse scanning force microscopy, it was found that the sample HIP-treated under 1.8 MPa exhibited the highest saturated piezoelectric coefficient. [ABSTRACT FROM AUTHOR]