BaTiO3 Nanocomposite Films Research Articles

High electric field-induced ferroelectric loss of polymer/paraelectric barium titanate particle nanocomposites

Polymer nanodielectrics have manifested high energy densities for potential applications in film capacitors. However, ferroelectric-like large hysteresis is often observed in the bipolar polarization–electric field (P-E) loops, even though neither the polymer matrix nor the ceramic nanoparticle exhibits any intrinsic ferroelectricity. To understand this abnormal ferroelectric behavior, poly(vinyl pyrrolidone) (PVP)/60 nm BaTiO3 (BTO60) nanocomposite films were fabricated with uniform BTO60 nanoparticle dispersion. PVP was a linear dielectric polymer with an apparent dielectric constant of 6.8 and BTO60 was found to be paraelectric. When the volume fraction of BTO60 was above 30 vol%, broad ferroelectric P-E loops were yielded. Using a theoretical deconvolution of the broad P-E loops based on the Langevin-type function, three contributions were identified. First, deformational polarization generated the linear dielectric constant of nanocomposites, from which the linear dielectric constant of BTO60 nanoparticles was extracted using the Bruggeman mixing rule. Second, slim paraelectric P-E loops were obtained for the BTO60 nanoparticles. From the saturated polarization, the electric field-induced permanent dipole moment per unit cell was estimated to be 0.07–0.2 D at a poling field of 20–100 MV/m, which was significantly smaller than the dipole moment (5.3 D) of the tetragonal unit cell of BaTiO3, indicating the paraelectric nature of BTO60 nanoparticles. Third, strong particle–particle dipolar interactions induced transient ferroelectric domains among the high dielectric constant BTO60 nanoparticles, particularly when the poling electric field was high. The third contribution dominated the overall polarization process and thus accounted for the abnormal ferroelectric behavior for the linear dielectric polymer/paraelectric ceramic nanoparticle composites. The knowledge gained from this study will pave the way towards developing better strategies for polymer nanodielectrics in the applications of capacitive energy storage.

BaTiO3@PVDF-TrFE nanocomposites with efficient orientation prepared via phase separation nano-coating method for piezoelectric performance improvement and application to 3D-PENG

Piezoelectric organic–inorganic hybrid nanocomposites utilize the advantages of high piezoelectricity of piezoelectric ceramics as well as the dielectric properties and flexibility of polymers. BaTiO3 particles that are nano-coated using the phase separation nano-coating method have effective orientation due to interaction with the PVDF-TrFE polymer chain. After mixing the piezoelectric BaTiO3 nanoparticles with the PVDF-TrFE matrix, an organic–inorganic hybrid nanocomposite film with enhanced efficiency characteristics of inorganic piezoelectric particles, and the flexibility and processability of the polymer was fabricated. The piezoelectric organic–inorganic hybrid nanocomposite film, in which the BaTiO3 coated with a polymer layer of about 5 nm or less, was dispersed and produced an output voltage of 59.5 V and an output current of 6.52 μA at a relatively low compression pressure of 100 N and frequency of 2.5 Hz. The result was about 4.8 times and 2 times higher than that of pure PVDF-TrFE and BaTiO3 nanocomposite dispersed films, respectively. The output power was measured against the external load resistance. On the other hand, the maximum output power value was measured to be 165.8 μW. In addition, by using the excellent processability of the uniformly dispersed BaTiO3@PVDF-TrFE nanocomposite solution, the piezoelectric nano-generator was implemented in a new form, in which the existing form factor was changed by coating on a three-dimensional shape as well as a two-dimensional flat film.

The structure and optical properties of PVA-BaTiO3 nanocomposite films

Abstract This paper aims to synthesize barium titanate (BaTiO3) nanocrystalline particles and to fabricate polyvinyl alcohol (PVA) films hosting BaTiO3 in order to enhance structural and optical properties. The tartrate precursor process is used to produce BaTiO3 nanocrystalline. By means of cast solution, the PVA – BaTiO3 nanocomposite films are prepared. The polymer films are described by X-ray diffractometer (XRD), Fourier-Transform Infrared (FTIR), UV–vis spectroscopy, and photoluminescence spectroscopy (PL). The study of XRD and FTIR indicates that complexity is established between BaTiO3 nanoparticles and PVA matrix. Furthermore, XRD analyzes emphasize a reduction in the crystallinity of polymer films by increasing of BaTiO3 nanoparticles within the matrix of PVA. It is noticed that as the BaTiO3 nanoparticles concentration increases in the PVA matrix, the optical band gap decreases while the Urbach energy increases. The PL spectra for PVA-BT films showed a photoemission peak at about 750 nm. This peak decreases in intensity and broadened with the increase of the BT concentration in the PVA matrix, which is related to the defects produced and causes disordering in the polymer matrix. The extinction coefficient, refractive index, optical conductivity and dielectric constants of the polymer films are also improved.

Structure, optical, and radiation shielding properties of PVA–BaTiO3 nanocomposite films: An experimental investigation

Developing different types of radiation shielding with certain specifications according to the type of radiation and method of application is essential. In this work, the radiation shielding, optical and structural features of PVA films containing BaTiO3 nanoparticles are investigated. The radiation shielding properties were measured experimentally with real gamma sources (133Ba, 152Eu, and 137Cs). The efficiency calibration and spectrum analysis were performed with the Spectra Line Ultimate Gamma Lab packet program. Moreover, the results were compared with the FLUKA Monte Carlo code. Before radiation attenuation measurements, the prepared films were characterized via X-ray diffraction (XRD). The structure of the BaTiO3 nanoparticles in the polymer matrix was studied with a scanning electron microscope (SEM, Merlin, Carl-Zeiss, LEO982). In addition, the optical properties of the polymer films were studied and presented. As the BaTiO3 content increases in the polymer matrix, transmission decreases and reflectance increases. Equally, as the BaTiO3 content increases, the value of α increases. For the shielding properties, the mass attenuation coefficient (μm) increases as the BaTiO3 content increases from 0.65 to 3.57 wt%. There is a strong agreement between experimental results and the values obtained from the FLUKA Monte Carlo code.

Effect of 80 MeV O6+ ion irradiation on structural, morphological, dielectric, and ferroelectric properties of (1-x)PVDF/(x)BaTiO3 nanocomposites

The polyvinylidene fluoride/barium titanate (1-x)PVDF/(x)BaTiO3 nanocomposite films (x = 0.2 and 0.5) were prepared by solution mixing method. The dielectric constant (e′) was increased by the BaTiO3 incorporation in the PVDF matrix. The pristine PVDF and nanocomposite films were uniformly irradiated with 80 MeV O6+ ion beam over an area of 1 cm2 at room temperature under the high vacuum of ~ 5 × 10−6 Torr with ion fluences, 5 × 1010, 2 × 1011, and 2 × 1012 ions/cm2. After irradiation, recrystallization and α→β phase transition were observed in PVDF through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analysis. However, almost complete amorphization was observed in BaTiO3 filler in (1-x)PVDF/(x)BaTiO3 nanocomposite samples. After irradiation, the dielectric constant (e′) increases at lower fluence (5 × 1010 ions/cm2) while decreases at higher fluence (2 × 1012 ions/cm2) as compared with the pristine samples. The creation of free radicals in PVDF due to chain scission and crosslinking observed upon irradiation is responsible for the observed behavior of dielectric constant (e′). While in nanocomposites, the change in the dielectric properties of BaTiO3 in nanocomposites samples after irradiation can be associated with the radiation-induced amorphization of BaTiO3. After irradiation, both the remanence polarization and coercive field increase for PVDF while decrease for nanocomposite samples. The observation of amorphousity in BaTiO3 phase through swift heavy ion irradiation is interesting and important from a fundamental point of view.

Effect of 40 MeV Li3+ ion irradiation on dielectric and ferroelectric properties of (1-x)PVDF/(x)BaTiO3 nanocomposites

The (1-x)PVDF/(x)BaTiO3 nanocomposite films were prepared by solution mixing method. The dielectric constant (ε′) was increased by the BaTiO3 incorporation in PVDF matrix. Further, the pristine PVDF and (1-x)PVDF/(x)BaTiO3 nanocomposite films were irradiated with 40 MeV Li3+ ion beam from 15 UD Pelletron at Inter University Accelerator Center, New Delhi. The uniform irradiation effect is observed as the projected range values (calculated from SRIM-2008) are much larger than the sample thickness (∼0.06 mm). After irradiation, recrystallization and α→β phase transition were observed in PVDF. However, almost complete amorphization was observed in BaTiO3 filler in (1-x)PVDF/(x)BaTiO3 nanocomposite samples. After 40 MeV Li3+ ion irradiation, the dielectric constant (ε′) and remanence polarization decrease for all the samples while, the coercive field increases. This is interesting to note that BaTiO3 phase is amorphized through 40 MeV Li3+ ion irradiation, which also causes to decrease the dielectric constant along with cross-linking effect in (1-x)PVDF/(x)BaTiO3 nanocomposite films.

Characterizations of P(VDF-HFP)-BaTiO3 nanocomposite films fabricated by a spin-coating process

Abstract In this work, free-standing and flexible polymer-ceramic nanocomposite films were fabricated by a spin-coating process using poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] as matrix and BaTiO3 (BTO) nanoparticles as filler. The relationships between the properties and compositions were systematically investigated. It is experimentally found that the crystallinity and the size of crystals of the P(VDF-HFP) matrix decreases with increasing BTO content. The dielectric responses of the polymer used as matrix were determined by four dielectric processes. Both the temperature and frequency dependences of the dielectric responses obtained in the composite films are mainly determined by the polymer matrix, and the influences of the ceramic filler on the four dielectric processes of the polymer matrix were discussed.

Behaviour of multiphase PVDF in (1−x)PVDF/(x)BaTiO3 nanocomposite films: structural, optical, dielectric and ferroelectric properties

The present paper deals with the synthesis and characterization of (1−x)PVDF/(x)BaTiO3 nanocomposite films with x = 0.1, 0.2, 0.3, 0.4 and 0.5. The samples were synthesized by simple solution mixing method followed by tape casting process. FESEM images show the homogeneous dispersion of BaTiO3 nanoparticles within the matrix of poly(vinylidene fluoride) (PVDF) with slight agglomeration. An improvement in the thermal stability of nanocomposite film is observed by TGA results. XRD as well as FTIR analysis indicate the α–β phase transition of PVDF in the nanocomposite films. The embedded BaTiO3 forms an intermediate band among the PVDF structures and thus decreases the band gap of nanocomposite films by absorbing the wavelength of lower energies. The band gap of nanocomposite films for x = 0.4 decreases to 2.4 eV as compared to 5.0 eV for pristine PVDF. The dielectric constant (ɛ′) of pristine PVDF at 50 Hz is 8.9, which increases to 26.7 for (0.6)PVDF/(0.4)BaTiO3 nanocomposite film. An increase in the charge storage ability is observed from PE loops, as (0.6)PVDF/(0.4)BaTiO3 nanocomposite film has highest value of polarization (0.093 µC cm−2) as compared to pristine PVDF (0.020 µC cm−2). This shows an increase in the charge storage ability of (1−x)PVDF/(x)BaTiO3 nanocomposite films as compared to pristine PVDF.

Preparation and Thermal Properties of Silicon-containing Polyimide Composite Films

Aromatic polyimide is a kind of polymer material with high temperature resistance, low temperature resistance, radiation resistance, excellent chemical stability, excellent electrical properties and good mechanical strength. It has been widely used in aerospace, electrical and electronic fields. At present, the synthesis, properties and application of polyimide containing silicon is one of the hot spots in the research field of polyimide. The processing property of polyimide can be greatly improved by introducing silicon group or polysiloxane segment into the main chain structure. And it has been given a good solubility, permeability, impact resistance, UV resistance and anti-degradation in oxygen rich environment. The introduction of siloxane chain segments or silicon containing groups in polyimide framework can enhance the adhesion between polyimide and inorganic materials, including the adhesion of metal materials and other substrates. A variety of polyimide hybrid materials can be prepared by the excellent bonding properties. A series of polyimide / silicon containing polyimide / BaTiO3 nanocomposite films were prepared and their structures and properties were studied in this paper. In addition, the preparation, structure and properties of polyimide / mesoporous silica composite films were studied. Silicon containing polyimide/silane mesoporous silica composite films have low infrared emissivity compared with bulk polyimide. Under the same content of mesoporous silica, the composite films prepared by copolymerization have lower infrared emissivity. Moreover, the infrared emissivity decreases with the increase of the content of silica. In short, silicon containing polyimides and their composite films with excellent performance differ from other traditional polyimides, and it has broad application prospects in the technological field of aerospace, electrical and electronic, gas separation, absorbing material preparation.

Growth and optical properties of FePt:BaTiO3 nanocomposite films

FePt:BaTiO3 nanocomposite films consisting of a regular stacking of pure BaTiO3 (BTO) layers and BTO layers embedding FePt nanocrystals were grown on (001) MgO substrates by pulsed laser deposition. Transmission electron microscopy experiments on cross-sectional specimens demonstrated the high quality of the epitaxial growth of the different layers, whatever their composition. The structural analysis also gave evidence of a misfit strain relaxation at the BTO/MgO interface. We report and discuss the optical and pholuminescence properties of the nanocomposite films in comparison with the ones recorded in pure BTO films. Our results emphasize the role of nanostructuration and growth processes on the evolution of the observed properties.

SPR enhanced photocatalytic properties of Au-dispersed amorphous BaTiO3 nanocomposite thin films

Aux/BaTiO3 (x = 0, 5, 10, 15, 25, 35, and 45, where x is mol% of Au) composite thin films dispersed by Au nanoparticles (NPs) were prepared by a sol–gel spin-coating approach. The crystal structure, optical and photocatalytic properties of the films were investigated with a special emphasis on the influences of x. The approximately spherical Au NPs with 20–45 nm in diameter are embedded uniformly in the amorphous BaTiO3 matrix. The absorption peaks appeared at the wavelength from 580 to 620 nm are due to the surface plasmon resonance (SPR) effect of Au NPs, and the SPR peaks generally manifest a red-shift with increasing x from 5 to 45. The Aux/BaTiO3 composite film with the optimal SPR effect (x = 35) exhibits the highest photocatalytic activity for the degradation of Rhodamine B (RhB) aqueous solution among all films under whole spectrum sunlight irradiation.

Fabrication of highly refractive BaTiO3 nanocomposite films using heat resistant polymer as matrix

Highly refractive, heat-resistant BaTiO3 nanocomposite films were fabricated via in situ polymerization to homogeneously disperse barium titanate (BT) nanoparticles into polyimide (PI) matrix. BT nanoparticles surface-modified with O-phosphorylethanol phthalimide (PPHI) were employed to the in situ polymerization in which condensation reactions of a diphthalic anhydride and a diamine were conducted to form the prepolymer of poly(amic acid) (PAA) that was thermally imidized in the following step. The nanoparticles surface-modified were added to PAA solution at different times in the polymerization to examine the effect of PAA molecular weight on the refractive index (RI) of the nanocomposite films, which indicated that relatively low molecular weights (<10,000) of PAA formed at the point of nanoparticle addition was appropriate for enhancement of nanocomposite RI. An additional treatment of chemical imidization using acetic acid anhydride and pyridine, which was followed by the thermal imidization, was performed to examine the effect of polyimide structure on RI of nanocomposite films. The RI of nanocomposite films with excellent thermal stability could be successfully enhanced to n=1.88 by the chemical imidization.

Effects of morphology and strain on the dielectric response of multiferroic CoFe2O4–BaTiO3 nanocomposite thin films

The dielectric response (permittivity and losses) of epitaxial CoFe2O4–BaTiO3 thin film nanocomposites deposited under different conditions has been measured. Exhaustive microstructural analyses have allowed tracking the evolution of structure and morphology as a function of thickness, deposition temperature and rate. It is found that the dielectric permittivity of the nanocomposite increases with the grain size of the BaTiO3 matrix and when reducing its unit cell volume, while losses are quite insensitive to changes in morphology and crystal structure of the ferroelectric phase. We analyze the consequences of these results in view of the functional optimization of nanocomposites.

Optical Properties of Co-BaTiO3/Mg(100) Nano-Composite Films Grown by Pulsed Laser Deposition Method

Co nanoparticles embedded in a BaTiO3 matrix, namely Co-BaTiO3 nano-composite films are grown on Mg(100) single crystal substrates by the pulsed laser deposition (PLD) method at 650°C. Optical properties of the Co- BaTiO3 nano-composite films are examined by absorption spectra (AS) and photoluminescence (PL) spectra. The results indicate that the concentration of Co nano-particles strongly influences the electron transition of the Co-BaTiO3 nano-composite films. The PL emission band ranging from 1.9 to 2.2 eV is reported. The AS and PL spectra suggest that the band gap is in the range of 3.28-3.7 eV.

Fabrication, microstructure and UPS spectra of Co: BaTiO3/Si(100) nano-composite films

Co: BaTiO3 nano-composite films were successfully fabricated by pulsed laser deposition on single crystal Si(100) surface. The micro-structure of the Co: BaTiO3 nano-composite films with about 30 nm and 100 nm thicknesses were studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The Co: BaTiO3 nano-composition films with the above thicknesses were unidirectionally prefer-oriented and polycrystalline, respectively. The atomic force microscopic (AFM) analysis indicated that there were tetragonal crystal grains in the films of about 30 nm thickness. The valence band of the films were investigated by ultraviolet photoelectron spectroscopy (UPS) in detail. The UPS spectra showed that density of electronic states (DOS) of the films with high concentration of Co grains were obviously different from that of bulk BaTiO3 single crystal.

Formation of Al2O3–BaTiO3 nanocomposite oxide films on etched aluminum foil by sol–gel coating and anodizing

Barium titanate BaTiO3 (BT) sol was dip-coated on the etched aluminum foils by a sol–gel process. After annealed at 600 °C in air, the foils were anodized in ammonium adipate solution. The voltage–time variations during anodizing were monitored. The structure, composition, and electric properties of the anodic foils were investigated. The obtained foils were fabricated into aluminum electrolytic capacitors and the load and shelf life test were measured. It was found that the slope of the voltage–time curve of aluminum foil covered with BT films became steeper. A triple layer of Al/Al2O3/BT was formed after anodizing Al/BT foil. The specific capacitance and the product of specific capacitance and withstanding voltage of anodic foil with a BT coating were about 46.36% and 38.90% larger than that without a BT coating. After the load life and shelf life of 2500 h at 85 °C, two kinds of capacitors have similar behaviores and meet with Nichicon standard of Japan. From the results, BaTiO3 is promising to be used as the dielectric of aluminum electrolytic capacitor to increase the specific capacitance.

Large optical nonlinearities in Ag-doped BaTiO3 nanocomposite films

Ag-doped BaTiO3 nanocomposite films have been synthesized on MgO substrates by excimer laser deposition. X-ray diffraction was used to characterize the structure and crystallinity of the films. The Ag chemical band and concentrations in the composite films were determined by X-ray photoelectron spectroscopy. The optical absorption were measured in the range of 300 to 800 nm and the absorption peaks due to the surface plasmon resonance of Ag particles were observed. z-scan results showed that the films exhibited large optical nonlinearities and the signs of the nonlinear absorption, β, and nonlinear refractive index, n2, changed with the increase of Ag concentration. The mechanism of the enhanced optical nonlinearities in Ag: BaTiO3 films is discussed.

Effects of the morphology and nanostructure on the optical nonlinearities of Au:BaTiO3 nanocomposite films

Metal nanocomposite thin films formed by nanometer-sized gold particles embedded in BaTiO3 matrices (Au:BaTiO3) were fabricated on MgO (100) and glass substrates using a pulsed-laser deposition technique. The high-resolution transmission electron microscopy analysis indicated that the morphology of gold particles and the structure of BaTiO3 matrices changed remarkably with the change of the substrate temperatures. Crystal lattice fringes from the Au nanocrystals and BaTiO3 matrices were clearly observed. The nonlinear optical properties of the Au:BaTiO3 nanocomposite films were measured using the Z-scan method at the wavelength of 532 nm. A sign reversal was demonstrated in the nonlinear absorption coefficient (β) and the nonlinear refractive index (n2) of Au:BaTiO3 films with the same Au concentration but a different nanostructure.