Nanocrystalline Mullite Synthesis at a Low Temperature: Effect of Copper Ions

Bagchi, Biswajoy; Das, Sukhen; Bhattacharya, Abhishek; Basu, Ruma; Nandy, Papiya

doi:10.1111/j.1551-2916.2008.02910.x

Cited by 48 publications

(44 citation statements)

References 27 publications

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“…FTIR band at 1,170 cm -1 is more intense than the band at 1,130 cm -1 for orthorhombic mullite, while the opposite indicates the domination by the tetragonal phase [23]. The absence of band in the 1,070-1,090 cm -1 range indicates that there is no amorphous silica phase in the oxide network [8]. Broad peak observed at 1,100 cm -1 for temperatures of 600 and 800°C shifted upon heat treatment above 850°C and the spectra show a strong band at *1,110 cm -1 , with a weak shoulder which is attributed to tetrahedral (Si-O) vibrations in mullite.…”

Section: Membrane Characterizationmentioning

confidence: 86%

“…It is assumed that stable mullites exist in the range of compositions between 3Al 2 O 3 Á2SiO 2 (3:2) and 2Al 2 O 3 ÁSiO 2 (2:1) [3]. Sol-gel processing has been used during the last decade for mullite preparation with chemically homogeneous microstructures [4][5][6][7][8][9]. The observation of mullitization at relatively low temperatures is commonly reported to be due to molecularnano scale mixing of the precursor phases achieved through sol-gel processing.…”

Section: Introductionmentioning

confidence: 99%

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Preparation and characterization of diphasic sol-gel derived unsupported mullite membranes

Topuz

Çiftçioğlu

2010

J Sol-Gel Sci Technol

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Diphasic gels prepared by mixing freshly prepared polymeric silica and polymeric boehmite sols through a modified Al-alkoxide route in mullite compositions led to the crystallization of mullite upon heat treatment at 775°C. Mullite formation was observed at a 100°C higher temperature when diphasic gels were formed by mixing aged polymeric sols containing about 2 nm in diameter boehmite species. These relatively low mullite formation temperatures were attributed to the nanoscale sizes of the polymeric species of the two amorphous phases present in the diphasic gels.

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Section: Membrane Characterizationmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Preparation and characterization of diphasic sol-gel derived unsupported mullite membranes

Topuz

Çiftçioğlu

2010

J Sol-Gel Sci Technol

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“…), and also there are some recent publications related to the dielectric properties and magnetic properties of these modified mullite composites [8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 96%

“…Iron based composites can be used in high-speed circuits and as high package density substrate [4]. [13,14]. The sol's Gelation took place after vigorous stirring for 3 hours and the sol was maintained overnight at 60°C.…”

Section: Introductionmentioning

confidence: 99%

Dielectric and magnetic properties of sol–gel derived mullite-iron nanocomposite

et al. 2012

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Synthesis of highly crystallized mullite has been achieved at a temperature of 1000°C by sol-gel technique in presence of iron ions of different concentrations. XRD, FTIR spectroscopy, FESEM, LCR meter and HyMDC, Hysteresis measurement instrument, characterized samples. Mullite formation was found to depend on the concentration of the ions. The dielectric properties (dielectric constant, tangent loss and a.c. conductivity) of the composites have been measured, their variation with increasing frequency and concentration of the doped metal was investigated, and magnetic behavior was observed from the hysteresis loops. All the experimentations were performed at the room temperature. The composite showed a minimum dielectric constant of 3.26 at 0.002(M) concentration of iron at 1.5 MHz and the magnetic properties of nanocomposites suggest that the iron nanoparticles show hysteresis loop in 0.10 M, 0.15 M and 0.20 M , hence acts like typical paramagnetic materials as is the case for other iron-doped ferrisilicates.

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“…Mullite whiskers have attracted attention as a possible reinforcement for high temperature structure materials. Various processing routes have been reported for the preparation of mullite whiskers such as sol-gel [1,2], high-energy ball milling process [3][4][5], internal crystallization method [6] and thermal decomposition of minerals [7]. However, these conventional synthesis methods have apparent shortcomings that the reactive system needs providing higher crystallization temperature and longer crystallization time.…”

Section: Introductionmentioning

confidence: 99%

Mullite whiskers prepared by molten salt method using Si powders

Wang

Guo

et al. 2012

J Adv Ceram

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Mullite whiskers were prepared from Si powders in molten Al 2 (SO 4 ) 3 -Na 2 SO 4 mixture salts with different Al/Si molar ratio (R) of raw materials. The resulting mullite whiskers, had been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and infrared spectroscopy analysis (FT-IR). Mullite phase was obtained in molten salts when the temperature reached at 850 ℃. SEM and EDS results revealed that two kinds of microstructures were formed in the final product, Al-rich mullite pellets and clusters of tiny mullite crystals, and the content of Al-rich mullite pellets increased with the higher Al/Si molar ratio (R) adopted in raw materials. A new oxidation-dissolution mechanism was proposed to explain mullite whiskers growth. According to thermodynamic analysis, mullite phase might be spontaneously formed as the temperature reached the decomposition temperature of aluminum sulfate (1023 K).

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Nanocrystalline Mullite Synthesis at a Low Temperature: Effect of Copper Ions

Cited by 48 publications

References 27 publications

Preparation and characterization of diphasic sol-gel derived unsupported mullite membranes

Preparation and characterization of diphasic sol-gel derived unsupported mullite membranes

Dielectric and magnetic properties of sol–gel derived mullite-iron nanocomposite

Mullite whiskers prepared by molten salt method using Si powders

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