Size Effects Observed via the Electrical Response of BaTiO₃ Nanoparticles in a Cavity

Abstract

Barium titanate (BaTiO3) is one of the most widely used electronic materials. The origin of changing structural and electronic behavior between larger and smaller nanoparticles in BaTiO3 has been extensively investigated. Here, the dielectric loss measured for BaTiO3 or BaZrO3 particles in a cavity at audio frequencies (10–105 Hz) and low temperatures (5.5–350 K) is reported. Distinct differences were found between small (50–100 nm diameter/cubic) and large (>200 nm diameter/tetragonal at room temperature) BaTiO3 particles. Isochronal relaxation features observed around 20 K showed differing shape and dynamics (50–100 nm particles: broad peak, E act ≈ 0.04 eV, log10(f pre(s)) ≈ 14.7; >200 nm particles: sharp peak, E act ≈ 0.025 eV and log10(f pre(s)) ≈ 12, with a shoulder). The low-temperature relaxations are attributed to the motion of off-center titanium ions. In support of this identification, low-temperature relaxations were not observed in BaZrO3 nanoparticles. Finally, structural change features were observed at about 180 and 270 K in the larger BaTiO3 particles (rhombohedral at low temperature) but not in the smaller particles (cubic at all temperatures). The results provide a new set of testable bounds that should contribute to the understanding of nanoparticle-sized BaTiO3, in particular, and ferroelectric behavior in perovskites, in general.

Morphology and polarization-dependent second harmonic generation in single hexagonal sodium niobate micro/nano-crystals

“…1-3) defined by O(c,y,j), which were determined to be (52. 31 Motivated by the advantages of SHG imaging probes (such as their stability, tunability, coherence, speed, and polarization sensitivity), 1,2,7,16,[19][20][21][23][24][25][26][27][28] investigators have recently applied nonlinear materials to biological imaging. For example, Culic-Viskota et al 35 have used BaTiO 3 SHG nanoprobes to greatly improve the signal-to-noise ratio (SNR) of in vivo images in living zebra fish embryos.…”

“…Since SHG only takes place in a noncentrosymmetric environment under an electric dipole approximation, 1 noncentrosymmetric crystalline nanomaterials are efficient in SHG. Studies of the SHG process have been carried out for various noncentrosymmetric nanocrystals, including ZnO, [9][10][11][12] KTiOPO 4 (KTP), 16,18,24 Fe(IO 3 ) 3 , 19,22 GaAs, 26 XNbO 3 (X = Li, Na, K), 20,29 BaTiO 3 , 21,25,[30][31][32] etc. Herein, we present the results of our study of SHG responses from single hexagonal NaNbO 3 micro/nano-crystals with different morphologies and sizes (samples No.…”

Second-Harmonic Generation of Single BaTiO3 Nanoparticles down to 22 nm Diameter

“…Moreover, crystallographic transitions may occur, with important consequences on certain materials that may lose their particular characteristics. Such materials are, for instance, noncentrosymmetric crystals like barium titanate (BaTiO 3 ), widely used in the electronic industry and more recently exploited in bioimaging for their strong second-order nonlinear optical property as bulk and down to 100 nm in diameter. , Modifications of the ferroelectricity and crystallography with sizes have been under investigation for many years, − giving sometimes not unique results due to properties highly dependent on the synthesis method. The size at which those properties may change is then critical to ensure the success of their future applications as high density memories or biomarkers.…”

“…Most of the aforementioned studies are focused on the electronic and structural characteristics of BaTiO 3 using X-ray diffraction, , conductance measurements, Raman spectroscopy, or high-resolution techniques as electron holography . To our knowledge, no investigations of the nonlinear optical properties have been performed on BaTiO 3 particles below 50 nm in diameter.…”

Structure and Electrical Conductivity of Irradiated BaTiO3 Nanoparticles

“…These changes are attributed to oxygen group wherein the permanent electric dipole moment associated with oxygen enhances the contribution to electric conductivity depending on the arrangement of these in the lattice. For some irradiation, the vector sum of these quantities gives lesser/greater contribution to physical properties, in addition to contribution from off‐centering of Ti ions . Variation in Grüneisen parameters do suggest that there is a change in vibrational relaxation in BaTiO 3 due to the off‐centering of Ti ions, which do change the electrical properties.…”