Ferroelectric Barium Titanate Nanoparticles Research Articles

Dielectric anisotropy changes in MBBA liquid crystal doped with barium titanate by a new method

In response to the burgeoning interest in enhancing the properties of liquid crystal composites, this research systematically explores the intricate interplay between MBBA nematic liquid crystals and ferroelectric barium titanate nanoparticles. The focus is modulating dielectric properties under temperature, frequency, and an applied electric field. Nuanced insights into temperature-dependent behavior, parallel and perpendicular component alterations, and a nonlinear correlation between nanoparticle concentration and dielectric constant are revealed. The study delves into dielectric anisotropy, indicating a reduction with increasing temperature. Structural analyses validate size reduction and crystal phase maintenance of barium titanate nanoparticles (NPs), emphasizing their impact on dielectric characteristics. Frequency-dependent investigations underscore a consistent decline in permittivity with rising frequency across nanoparticle concentrations. Application of an electric field in filling process of liquid crystal cells reveals irregular changes in dielectric constant, holding promise for tailored applications in display technologies. These comprehensive findings offer valuable insights into manipulating dielectric anisotropy properties of MBBA liquid crystal by a simple method for potential advancements in optoelectronic devices and display technologies.

Nematic liquid crystals blended ferroelectric nanoparticles (BaTiO3): A perspective way for improving the response time and photoluminescence for electro-optical devices

We represent a detailed study of a dilute suspension of ferroelectric barium titanate nanoparticles (BaTiO3 NPs) in a nematic matrix by probing dielectric, electro-optical, and optical properties. The strong local surface electric field (order of ∼1010 Vm−1) of BaTiO3 produces pseudonematic domains within the matrix, which renders an enhancement in both the perpendicular and parallel components of dielectric permittivity that increases with increasing NP concentrations. Due to changes in molecular ordering, the dielectric anisotropy of pristine nematic increases by 10.7%, 24.6%, and 33.3% after the addition of 0.1, 0.3, and 0.5 wt. % BaTiO3 NPs with subsequent lowering in threshold voltage. Interestingly, the nematic-BaTiO3 blended cells showed 23.2%, 49.3% and 67.6% faster electro-optic response for 0.1, 0.3, and 0.5 wt. % of NPs, respectively. In the nematic matrix, BaTiO3 NPs act like chromophores resulting in a bathochromic shift in fluorescence spectra due to an enhanced degree of conjugation. This investigation reveals that the ferroelectric BaTiO3 NPs-nematic composites will be suitable for superior fluorescent electro-optical devices.

Corrigendum/Addendum to “Strengthening of columnar hexagonal phase of a room temperature discotic liquid crystalline material by using ferroelectric barium titanate nanoparticles” [J. Mol. Liq. 294 (2019) 111609

In this Corrigendum/Addendum, we present correction to our published article “Strengthening of columnar hexagonal phase of a room temperature discotic liquid crystalline material by using ferroelectric barium titanate nanoparticles” [J. Mol. Liq. 294 (2019) 111609]. Correction include Table 1: Thermodynamic parameters for RTAQ and composites. The effect of correction on the DSC thermogram is negligible, hence the results and discussion, and the conclusion section remains unchanged. However, for the convenience of readers, we correlate the discussion on the basis of corrected values with the discussion of previously published work.

Atomic-resolution characterization on the structure of strontium doped barium titanate nanoparticles

Ferroelectric barium titanate nanoparticles (BTO NPs) may play critical roles in miniaturized passive electronic devices such as multi-layered ceramic capacitors. While increasing experimental and theoretical understandings on the structure of BTO and doped BTO have been developed over the past decade, the majority of the investigation was carried out in thin-film materials; therefore, the doping effect on nanoparticles remains unclear. Especially, doping-induced local composition and structure fluctuation across single nanoparticles have yet to be unveiled. In this work, we use electron microscopy-based techniques including high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), integrated differential phase contrast (iDPC)-STEM, and energy dispersive X-ray spectroscopy (EDX) mapping to reveal atomically resolved chemical and crystal structure of BTO and strontium doped BTO nanoparticles. Powder X-ray diffraction (PXRD) results indicate that the increasing strontium doping causes a structural transition from tetragonal to cubic phase, but the microscopic data validate substantial compositional and microstructural inhomogeneities in strontium doped BTO nanoparticles. Our work provides new insights into the structure of doped BTO NPs and will facilitate the materials design for next-generation high-density nano-dielectric devices.

Strengthening of columnar hexagonal phase of a room temperature discotic liquid crystalline material by using ferroelectric barium titanate nanoparticles

A discotic liquid crystalline (DLC) material possessing a wide room temperature columnar hexagonal phase has been used as a polymeric matrix to disperse ferroelectric barium titanate nanoparticles at the concentrations of 0.5 wt% and 1.0 wt% respectively. The influence of nanoparticles on the discotic liquid crystal has been studied with the help of Differential Scanning Calorimetry, impedance spectroscopy, polarizing optical microscopy and Ultraviolet-Visible spectroscopy. Small angle X-ray scattering (SAXS) measurements have also been performed. Thermal measurements reveal stabilization of the columnar hexagonal phase due to the addition of ferroelectric nanoparticles in the discotic system. Permittivity is decreasing due to the formation of anti-dipolar ordering in the presence of ferroelectric nanoparticles. A relaxation mode is visible in the high kHz to low MHz region. The relaxation frequency has been found to decrease with the incarceration of barium titanate nanoparticles in DLC. A shift in UV–Vis absorption/transmittance spectra indicates modification in the electronic structure and hence physical property of the nanocomposites. SAXS explains the variation of different hexagonal lattice parameters with respect to the temperature.

Thermodynamical, optical, electrical and electro-optical studies of a room temperature nematic liquid crystal 4-pentyl-4′-cyanobiphenyl dispersed with barium titanate nanoparticles

Dispersion of ferroelectric Barium Titanate Nano Particles (BTNPs) in a nematic liquid crystal (NLC) display material namely 4-pentyl-4′-cyanobipheny (5CB) has been studied by differential scanning calorimeter, UV–Vis spectroscopy, polarizing light microscopy, dielectric spectroscopy and electro optical studies. BTNPs have been dispersed in three different concentrations in pure 5CB viz. 0.05, 0.5 and 5.0wt.%. It has been observed that with the increase of BTNP concentrations in 5CB, the nematic to isotropic transition temperatures, parallel components of dielectric permittivity and hence dielectric anisotropy decreases significantly unlike in the earlier studies. Threshold voltage for the Freedericksz transition, switching voltage and splay elastic constant have also decreased due to the dispersion of BTNPs. Relaxation frequency and activation energy of an observed relaxation mode corresponding to molecular rotation about the short axis are almost the same for pure and its nanocomposites. The ionic conductivity has increased by two orders of magnitudes for 0.05wt.% of nanocomposites. The optical study suggests that due to dispersion of BTNPs band gap has decreased.

Doping a Mixture of Two Smectogenic Liquid Crystals with Barium Titanate Nanoparticles

A mixture of two smectic liquid crystals was doped with harvested ferroelectric barium titanate nanoparticles and investigated with wide- and small-angle X-ray scattering during cooling from the isotropic phase. A decrease in the isotropic to nematic and in the nematic to partially bilayer smectic-A(d) (SmA(d)) phase transition temperatures was observed accompanied by an increase of the layer spacing in the SmA(d) phase.

Nanostructured barium titanate composites for embedded radio frequency applications

We describe a vapor-phase codeposition method to fabricate a ceramic-in-polymer composite system comprising ferroelectric barium titanate nanoparticles in a highly polarizable polyaniline-polyurethane copolymer host. As-deposited composites exhibited a capacitance density of 15nF∕cm2 and a resonance frequency close to 100MHz with a loss tangent of 0.8. Annealing nanocomposites at 135°C resulted in slightly reduced but frequency-independent capacitance density (∼10nF∕cm2) with a loss tangent of 0.1 and resonance frequency at 200MHz. The interplay of polarization modes is discussed in relation to capacitor performance. The fabricated capacitors have potential for applications in embedded technology in the radio frequency.

Room Temperature Synthesis of Ferroelectric Barium Titanate Nanoparticles Using Peptide Nanorings as Templates.

Tetragonal ferroelectric BaTiO3 nanoparticles are hydrolyzed inside peptide-ring templates at room temperature and pressure (see figure). The sizes of the monodisperse BaTiO3 nanoparticles are controlled between 6 and 12 nm by varying the cavity size of the nanorings as a function of pH. The nanoparticles possess switching behavior under the influence of external electric fields.