Direct Synthesis of Barium Titanate Nanoparticles Via a Low Pressure Spray Pyrolysis Method (original) (raw)
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Journal of the …, 2006
BaTiO3 nanocrystals were synthesized by using a low-pressure spray pyrolysis (SP) method. A new strategy was proposed to improve nanocrystal formation and phase evolution by ethanol addition and Ba/Ti molar ratio variation, respectively. A mixture of submicron and nanoparticles was found with SP of precursors without ethanol addition, while only nanoparticles could be obtained by ethanol addition. BaTiO3 crystal growth was improved by increasing the Ba/Ti ratio. In comparison, SP of the same precursor under atmospheric conditions resulted in only submicron particles with smooth surfaces and irregular morphology.
Formation of BaTiO 3 nanoparticles from an aqueous precursor by flame-assisted spray pyrolysis
Journal of the European …, 2007
By manipulating process parameters, BaTiO3 nanoparticles with tunable size were successfully prepared by flame-assisted spray pyrolysis (FASP) from an aqueous solution of barium acetate and titanium-tetra-isopropoxite. Particle size was controlled over a wide range (from about 23 to 71 nm) by varying the concentration of precursor and methane flow rate. Flame temperature was a key factor in producing particles with a narrow size distribution. The BaTiO3 nanoparticles were cubic in crystal structure, dense, spherical and softly agglomerated. The particles contained OH, carboxyl and CO2 bonding groups that could be completely removed by post-heat treatment. At room temperature, BaTiO3 pellets had relatively high dielectric constants (2578.8–3611.8) with loss factors ranging from 2.6% to 7.1% at the frequency of 1 kHz. The results of this study indicate that BaTiO3 nanoparticles can be fabricated using continuous and industrially applicable FASP.
Influence of Synthesis Method and the Precursor on the Preparationof Barium Titanate Nano Particles
2018
Different synthesis routes and different starting precursors can have different effects upon the properties of materials. In this paper, two different methods: solid state method, sol-gel method has been used to prepare BaTiO3 powders. BaCO3, Ba(OH)2.8H2O and [CH3COO]2Ba were used as barium precursor and TiO2, Ti[OCH[CH3]2]4] as titanium precursor. With the help of thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscope (SEM), the powder characterization has been compared. The results show that sol-gel derived powders are having larger grain growth compared to solid state powders irrespective of starting precursors. It is also evident that dielectric constant value is a function of grain size. Another important findings are starting precursor also plays a major role especially for the grain size and dielectric constant value. The barium hydroxide octahydrate precursor was showing better result than barium acetate precursor.
Agglomerate-free BaTiO3 particles by salt-assisted spray pyrolysis
Journal of materials …, 2002
Optimum conditions for the synthesis of nonagglomerated BaTiO 3 particles by salt-assisted spray pyrolysis (SASP) were investigated. The effect of particle residence time in the reactor and salt concentration on the crystallinity and surface morphology of BaTiO 3 was examined by x-ray diffraction and scanning electron microscopy. Mixtures of a metal chloride or nitrate salt, dissolved in aqueous precursor solutions, were sprayed by an ultrasonic atomizer into a five-zone hot-wall reactor. By increasing the salt concentration or the particle residence time in the hot zone, the primary particle size was increased, and its surface texture was improved compared to BaTiO 3 particles prepared by conventional spray pyrolysis. The SASP-prepared BaTiO 3 crystal was transformed from cubic to tetragonal by simply increasing the salt concentration at constant temperature and residence time. Further thermal treatments such as calcination or annealing are not necessary to obtain nonagglomerated tetragonal BaTiO 3 (200-500 nm) particles with a narrow size distribution. Increasing the carrier gas flow rate and decreasing the residence time in the hot zone resulted in cubic BaTiO 3 particles about 20 nm in diameter.
Ultrasonic assisted synthesis of BaTiO3 nanoparticles at 25 °C and atmospheric pressure
Ultrasonics Sonochemistry, 2018
Barium titanate (BaTiO 3) nanoparticles were successfully synthesized via a sonochemical method (25 kHz) at a constant temperature of 25°C and atmospheric pressure without a calcination step. Barium hydroxide Ba(OH) 2 and diisopropoxytitanium bis(acetylacetonate) (C 12 H 28 O 6 Ti) were used as the starting materials. The effects of the concentration of NaOH used and ultrasonic reaction time were investigated. The phase composition, functional groups and morphology of synthesized powders were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Fourier transform Raman spectroscopy (FT-Raman) and transmission electron microscopy (TEM). The XRD and FT-Raman results revealed the cubic structure of BaTiO 3. The optimal NaOH concentration and ultrasonic reaction time for producing a narrow particle size distribution and the bowllike structure of BaTiO 3 nanoparticles were 10 M and 1 h, respectively. TEM imagery showed their morphology as a monodispersed bowl-like structure with a size of 54.90 ± 18.18 nm. After longer ultrasonic contact times, the bowl-like structure tended to fracture forming irregularly shaped nano-sized BaTiO 3 particles.
Vibrational Spectroscopy, 2013
BaTiO 3 nanopowders were prepared at lower temperature and in shorter time span through a newly developed process. To reach an in-detail understanding of mechanism of the process, thermal analysis were performed using DTA/TGA and FT-IR techniques aided by in-depth discussions. The results indicated that thermal evolution of sol-gel-powder transformation consists of following steps: the vaporization of volatile organic solvents, the deformation of gel structure and pyrolysis of the Ba-Ti organic precursors, the decomposition of BaCO 3 into BaO and CO 2 , reaction of resulted BaO with TiO 2 to form BaTiO 3. The results also elucidated the reaction pattern and formation mechanism of BaTiO 3 nanopowders from gel-derived precursor.
Journal of Nanoparticle …, 2003
Highly crystalline, dense BaTiO3 nanoparticles in a size range from 30 to 360nm with a narrow size distribution (σg = 1.2–1.4) were prepared at various synthesis temperatures using a salt-assisted spray pyrolysis (SASP) method without the need for post-annealing. The effect of synthesis temperature on particle size, crystallinity and surface morphology of the nanoparticles were characterized by X-ray diffraction and scanning/transmission electron microscopy. The nature of the crystalline structure was analyzed by Rietveld refinement and Raman spectroscopy. The particle size decreased with decreasing operation temperature. The crystal phase was transformed from tetragonal to cubic at a particles size of about 50nm at room temperature. SASP can be used to produce high weight fraction of tetragonal BaTiO3 nanoparticles down to 64nm in a single step.