Supporting information

Large piezoelectric coefficient and ferroelectric nanodomain switching in

Ba(Ti0.80Zr0.20)O3-0.5(Ba0.70Ca0.30)TiO3 nanofibers and thin films A. Jalalian1,2, A. M. Grishin2, X.L. Wang1*, Z.X. Cheng1and S. X. Dou1*

1Institute for Superconducting and Electronic Materials, Faculty of Engineering, Australian

Institute for Innovative Materials, University of Wollongong, North Wollongong, NSW 2522,

Australia

2 Department of Condensed Matter Physics, KTH Royal Institute of Technology, SE-164 40

Stockholm-Kista, Sweden.

Sample fabrication procedure

Ba(Ti0.80Zr0.20)O3-0.5(Ba0.70Ca0.30)TiO3 nanostructures in the forms of thin films and nanofibers

were fabricated using spin-coating and electrospinning techniques, respectively. In order to

prepare the BTZ-0.5BCT precursor solution, barium acetate, calcium acetate monohydrate,

titanium butoxide, and zirconium (IV) propoxide were used as starting materials. Barium acetate

and calcium acetate monohydrate were dissolved in glacial acetic acid at 80°C for 1 hour and

cooled down to room temperature. Titanium butoxide and zirconium propoxide were chelated by

acetyl acetone and added to the Ba and Ca solution. 2-methoxyethanol was used to adjust the

concentration of the BTZ-0.5BCT precursor solution to 0.2 M. Spin-coating at 3000 rpm for 30

seconds was carried out to prepare the BTZ-0.5BCT thin film on Si and Si/SiO2/Ti/Ir substrates.

The spin-coated thin films were dried and annealed at 100°C and 600°C for 10 minutes,

respectively, and the above procedure was repeated for 4 cycles until the films reached a

thickness of about 200 nm, followed by calcination at 700°C for 1 hour in air. Nanofibers were

fabricated by adding 0.045 g/ml polyvinylpyrrolidone (PVP, MW = 1,300,000) to the precursor

solution and using the electrospinning technique under a 1.2 kV/cm DC electric field. The

nanofibers were collected on the same substrate used for the thin film and annealed at 700°C for

1 hour in air, under similar conditions as for the thin film.

FIG S1. FE-SEM image of the BTZ-0.5BCT thin film deposited on the Si/SiO2/Ti/Ir substrate

and annealed at 700°C for 1 hour in air. Inset: magnified view of the thin film surface.

FIG S2. X-ray diffraction patterns of the bulk sample used for Raman spectroscopy and of the

nanofibers annealed at 700°C.

FIG S3. Low magnification TEM image obtained from the nanofiber heat treated at 700° C

containing randomly oriented particles, and inset selected area electron diffraction pattern reveals

the polycrystalline structure of the nanofiber.

FIG S4. Energy dispersive x-ray spectroscopy (EDS) of the BTZ-0.5BCT nanofibers annealed at

700°C.

FIG S5. Raman spectra of the BTZ-0.5BCT bulk sample synthesized by solid state reaction at

1450°C for 1 hour. All peaks assigned to the polar structures of the BaTiO3 have appeared.

FIG S6. Force-distance curve recorded from the surface of a silicon substrate using the

cantilever employed in our PFM measurements. This plot was used for the optical sensitivity

calibration of the cantilever used in the PFM measurements.

The deflection of the cantilever created by the surface deformation of the piezoelectric material

is detected by a photodiode. The output voltage from the photodiode due to the displacement of

the LASER beam reflected from the cantilever surface represents the cantilever deflection.

Therefore an accurate calibration of the deflection sensitivity of the cantilever is essential in

PFM measurements. This calibration is conducted by acquiring a cantilever deflection in volts

versus piezo displacement in microns collected from a force-distance curve measurement. In our

calibration procedure, a silicon substrate was selected to provide a hard surface that could not be

indented by the tip in the calibration procedure. The deflection sensitivity of the cantilever was

obtained from the inversion of the slop of the deflection vs. piezo displacement in the linear part

of the repulsive region ( blue line). According to the calibration procedure, the sensitivity of the

cantilever used in our PFM measurements was 73.6 nm/V. Due to the dependency of this value

to the LAZER position on the lever, the LASER alignment was kept un-changed during the

measurement.