High Permittivity (1 - x)Ba(Zr(0.2)Ti(0.8))O3 - x(Ba(0.7)Ca(0.3))TiO3 (x = 0.45) Epitaxial Thin Films with Nanoscale Phase Fluctuations.
Epitaxial (1 - x)Ba(Ti0.8Zr0.2)TiO3 - x(Ba0.7Ca0.3)TiO3, x = 0.45 (BCZT 45), thin films have been deposited on (001) SrTiO3 (STO) and (001/100) SrLaAlO4 (SLAO) substrates by pulsed laser deposition. X-ray diffraction and high-resolution transmission electron microscopy (HRTEM) confirmed the epitaxial growth of the films. A high structural quality has been evidenced for the BCZT/STO films. Geometric phase analysis (GPA) associated with the HRTEM enabled us to obtain microstrain analysis and the in-plane and out-of-plane lattice parameter variation on different areas. Tetragonality ratio fluctuations at nanoscale level which are relevant for the existence of nanodomains have been evidenced on the BCZT/STO films. The in-plane dielectric constant has been measured on interdigital electrodes deposited by lift-off technique on the top of the films. High values of dielectric permittivity (>3000) combined with low dielectric loss (<0.01) are obtained for BCZT 45 film deposited on STO substrate, showing nearly constant values between 1 kHz and 10 MHz. The high dielectric permittivity of BCZT thin films was attributed to their high structural quality and to the loss of rotation stability of the polarization associated with the presence of nanodomains. This results into a divergence of fluctuations of polarization direction and a peak of dielectric susceptibility. The enhanced switching of such nanodomain configuration was probed by piezoforce microscopy, by writing and reading domains during topography scanning.
National Institute for Laser , Plasma and Radiation Physics, 409 Atomistilor, 077125 Magurele, Romania.
Nicu D
ND
Scarisoreanu
CNR-ISC, Istituto dei Sistemi Complessi, Area della Ricerca di Roma-Tor Vergata , Via del Fosso del Cavaliere 100, I-00133, Rome, Italy.
Floriana
F
Craciun
National Institute for Laser , Plasma and Radiation Physics, 409 Atomistilor, 077125 Magurele, Romania.
Antoniu
A
Moldovan
National Institute for Laser , Plasma and Radiation Physics, 409 Atomistilor, 077125 Magurele, Romania.
Valentin
V
Ion
National Institute for Laser , Plasma and Radiation Physics, 409 Atomistilor, 077125 Magurele, Romania.
Ruxandra
R
Birjega
National Institute of Materials Physics , 105 bis Atomistilor, 077125 Magurele, Romania.
Corneliu
C
Ghica
National Institute of Materials Physics , 105 bis Atomistilor, 077125 Magurele, Romania.
Raluca F
RF
Negrea
National Institute for Laser , Plasma and Radiation Physics, 409 Atomistilor, 077125 Magurele, Romania.
Maria
M
Dinescu
BCZT thin films; HRTEM; dielectric permittivity; geometric phase analysis; piezoforce microscopy