Entity

Time filter

Source Type


Hojamberdiev M.,Alfred University | Hojamberdiev M.,Xian University of Architecture and Technology | Hojamberdiev M.,TU Darmstadt | Eminov A.,Tashkent Institute of Chemical Technology | Xu Y.,Xian University of Architecture and Technology
Ceramics International | Year: 2011

Granite waste is by-product from a decorative rock industry. The present study aims to investigate the effect of muscovite granite waste on the physico-mechanical properties of ceramic tiles to demonstrate its suitability for industrial production. A series of flooring- and facing ceramic tiles were prepared by adding 20, 25, and 30 wt% muscovite granite waste into the batch compositions. The sintering behavior and degrees of densification of two kinds of ceramic tiles were evaluated by determining their physico-mechanical properties and characterizing them by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. As expected, the facing ceramic tile (FacCT1) sample, containing wollastonite, hematite, anorthite, quartz, and cristobalite, with 20 wt% muscovite granite waste showed lower physico-mechanical properties than those of the flooring ceramic tile (FloCT3) sample, containing mullite, calcium aluminosilicate, quartz, and cristobalite, with 30 wt% muscovite granite waste. The reason is that lower firing temperatures cannot accelerate a complete fusion of the granite waste which behaves like an inert non-plastic material similar to quartz. These results illustrate the prospects of utilizing muscovite granite waste in ceramic tile production. © 2010 Elsevier Ltd and Techna Group S.r.l. Source


Hojamberdiev M.,Shaanxi Normal University | Hojamberdiev M.,Tokyo Institute of Technology | Zhu G.,Shaanxi Normal University | Eminov A.,Tashkent Institute of Chemical Technology | Okada K.,Tokyo Institute of Technology
Journal of Cluster Science | Year: 2013

Hollow α-FeOOH urchin-like spheres were synthesized by a simple hydrothermal method at 160 °C for 12 h and their thermal conversion to hollow α-Fe2O3 urchin-like spheres was performed at 300 °C for 2 h in air. The results from X-ray diffraction and electron microscopy analyses reveal that hollow α-FeOOH urchin-like spheres were completely transformed to hollow α-Fe2O3 urchin-like spheres without a significant morphological change. Also, the effect of hydrothermal treatment temperature (170-200 °C for 12 h) on the phase structure and morphology of the final product was investigated. Pure α-FeOOH, the mixture of α-FeOOH and α-Fe2O3, and pure α-Fe2O3 with different morphologies were obtained at <180, 180-190 and 200 °C, respectively. The obtained materials can be used in the photodegradation of organic pollutants under visible light irradiation. © 2012 Springer Science+Business Media New York. Source


Krivorotov V.F.,Academy of Sciences of Uzbekistan | Khabibullaev P.K.,Academy of Sciences of Uzbekistan | Fridman A.A.,Academy of Sciences of Uzbekistan | Sharipov K.T.,Tashkent Institute of Chemical Technology
Inorganic Materials | Year: 2010

We examine the behavior of the entropy (S d), enthalpy (H), and concentration of disordered fluoride ions (n) in LaF 3 in a broad temperature range around its critical temperature using a model for structural lattice disordering. We analyze the relationship between the free energy of a crystal and LaF 3 lattice disordering parameters: entropy, S d; anion sublattice disordering energy, E a; and the concentration of vacancy-interstitial defect complexes, n. H(T), n(T), and S d(T) data are obtained for the phase transition region. © 2010 Pleiades Publishing, Ltd. Source


Krivorotov V.F.,Academy of Sciences of Uzbekistan | Khabibullaev P.K.,Academy of Sciences of Uzbekistan | Fridman A.A.,Academy of Sciences of Uzbekistan | Sharipov K.T.,Tashkent Institute of Chemical Technology
Inorganic Materials | Year: 2010

The energetics of lattice disordering in crystals with the LaF 3 structure has been studied by Raman spectroscopy. Analysis of the width of Raman lines indicates that, for T < T c (in the dielectric phase of LaF 3), the activation energy for anion disordering is E d ≃ 0.20 eV. This value agrees well with the 0.22 eV obtained as the difference between the energies of a fluoride ion in lattice and interstitial sites in a finite crystalline LaF 3 cluster. © 2010 Pleiades Publishing, Ltd. Source


Krivorotov V.F.,Academy of Sciences of Uzbekistan | Khabibullaev P.K.,Academy of Sciences of Uzbekistan | Sharipov K.T.,Tashkent Institute of Chemical Technology
Inorganic Materials | Year: 2010

The mechanism of lattice "melting" in tysonite-structure superionic trifluorides is analyzed in relation to the structure of LaF 3 crystals. The ion displacements within the unit cell are shown to correlate with the dynamics of the Raman scattering parameters of the crystals. The frequency and intensity of the lines at 370, 392 (LaF 3), 376, and 404 cm -1 (PrF 3) show anomalous behavior in three temperature ranges: 160- 180, 240-280, and 420-460 K. The anomalies in the two higher temperature ranges are due to lattice disor- dering in the superionic transition region. The scattering in the range 160-180 K is tentatively attributed to fluoride ion displacements in split sites with a few potential wells. It is shown based on a split-site model that the thermally activated formation of interstices comparable in size to the mobile fluoride ion is an inherent feature of the LnF 3 structure. © Pleiades Publishing, Ltd., 2010. Source

Discover hidden collaborations