The Experts below are selected from a list of 87 Experts worldwide ranked by ideXlab platform

A V Gorokhovsky - One of the best experts on this subject based on the ideXlab platform.

  • preparation and dielectric properties of ceramics based on mixed Potassium Titanates with the hollandite structure
    Inorganic Materials, 2016
    Co-Authors: A V Gorokhovsky, E V Tretyachenko, V G Goffman, N V Gorshkov, Fedor S Fedorov, A V Sevryugin
    Abstract:

    We have studied the crystallization of Potassium polyTitanates (PPTs) modified in aqueous solutions of salts of various transition metals. The results demonstrate that the modified materials crystallize in the form of solid solutions with the hollandite structure. Ceramic materials obtained using the PPT/Fe, PPT/Ni, and PPT/Co systems have high dielectric permittivity in the low-frequency region (e ~ 105), whereas PPT/Cu ceramics have lower e (~103), retaining it to a frequency of 1 MHz, and very low dielectric losses (tanδ ~ 10–2).

  • synthesis and characterization of high strength ceramic composites in the system of Potassium titanate metallurgical slag
    Ceramics International, 2015
    Co-Authors: Denis Kuznetsov, A V Gorokhovsky, J I Escalantegarcia, E Sanchezvaldes, I N Burmistrov
    Abstract:

    Abstract Ceramic composites based on different mixtures of the powdered slags from silicomanganese manufacturing and synthetic Potassium Titanates, were produced and investigated. Green bodies were fabricated by uni-axial compression at 35 and 196 MPa. The sinters were obtained by one-stage (1100 °C/1 h) or two-stage (800 °C/1 h and 1100 °C/1 h) thermal regimes. The best mechanical properties were achieved for conditions of 33 wt% of slag, compressed under 196 MPa and treated by the two-stage regime of sintering. Structural investigation of the processes taking place in the produced ceramic materials was carried out by scanning electron microscopy and X-ray diffraction. The resulting products were characterized by a gradient phase composition constituted by perovskite, leucite, Potassium hexatitanate, pyrophanite-ilmenite solid solutions, hollanadite-like and pyroxene-like crystalline phases as well as glassy phase of varied chemical composition. The mechanism of the sintering processes was also characterized.

  • molten salt synthesis and characterization of Potassium polytitanate ceramic precursors with varied tio2 k2o molar ratios
    Journal of the American Ceramic Society, 2008
    Co-Authors: Tomas Sanchezmonjaras, A V Gorokhovsky, J I Escalantegarcia
    Abstract:

    Semi-crystalline Potassium Titanates, useful as precursors to produce composite materials and coatings, were synthesized by thermal treatment of powdered TiO2 in molten mixtures of KNO3 and KOH at 4501–5501C. The products obtained had similar structures of laminar crystals, aggregated in particles of about 3 l mo fn 5 TiO2/K2O molar ratio in the range 2.8– 6.0. The value of n could be regulated by the temperature of synthesis, the weight ratio of [KOH]/[KNO3] in the molten salt mixture, and the number of water washing operations. The reduction of the TiO2/K2O molar ratio increased the contents of H2O in the composition of Potassium polytitanate, from 5.3 to 11.4 and from 0.2 to 8.6 (wt%) in the adsorbed and structural forms. The thermal treatment of the Potassium polytitanate precursors obtained resulted in dehydration and chemical interaction with unreacted TiO2 at 5001–7501C, amorphization at 7501–8501C, crystallization of K2Ti4O9 (in some cases K3Ti8O17 )a t 8501–10901C, and crystallization of K2Ti6O13 at temperatures 410901C. The mechanisms of the structural transformation and phase evolution were considered as a function of the TiO2/K2O molar ratio in the Potassium polytitanate.

Qiang Wang - One of the best experts on this subject based on the ideXlab platform.

  • catalytic combustion of diesel soot over perovskite type catalyst Potassium Titanates
    Kinetics and Catalysis, 2012
    Co-Authors: Xiuhong Meng, Qiang Wang, Linhai Duan, Jongshik Chung
    Abstract:

    Potassium Titanates with a high crystallinity were successfully prepared by the sol-gel method and characterized by XRD, SEM, and BET surface area measurements. K6Ti4O11, K2Ti2O5, K2Ti4O9 were found to have better soot oxidation performance compared with Pt/TiO2 and CeO2 based catalysts. K2Ti2O5 may be an excellent candidate for soot oxidation due to its high oxidation activity, water-stability, resistance to sulfur poisoning and economical advantages. Certain amount of NOx can contribute to the catalytic combustion of diesel over Potassium Titanates, implying that K2TiO5 may be a kind of catalyst for simultaneous removal of NOx and soot.

  • formation and structural characterization of Potassium Titanates and the Potassium ion exchange property
    Materials Research Bulletin, 2009
    Co-Authors: Qiang Wang, Zhanhu Guo, Jongshik Chung
    Abstract:

    Abstract In the present work, K 2 Ti 2 O 5 , K 2 Ti 4 O 9 and K 2 Ti 6 O 13 are synthesized by solid state method. Their structures and morphologies are characterized by X-ray diffraction, Raman spectra and scanning electron microscopy. The binding energies of K, Ti and O in Potassium Titanates were then evaluated by X-ray photoelectron spectroscopy and compared with those in K/TiO 2 . Finally the corresponding K ion exchange properties are investigated by synthesizing NO oxidation catalysts with Co(NO 3 ) 2 precursor. It is found that the binding energy of K in K 2 Ti 2 O 5 is much higher than those in K 2 Ti 4 O 9 and K 2 Ti 6 O 13 , and because of which, it shows quite different catalytic performances. Compared with other Potassium Titanates, the K in K 2 Ti 2 O 5 is much easier to be exchanged out.

J I Escalantegarcia - One of the best experts on this subject based on the ideXlab platform.

  • synthesis and characterization of high strength ceramic composites in the system of Potassium titanate metallurgical slag
    Ceramics International, 2015
    Co-Authors: Denis Kuznetsov, A V Gorokhovsky, J I Escalantegarcia, E Sanchezvaldes, I N Burmistrov
    Abstract:

    Abstract Ceramic composites based on different mixtures of the powdered slags from silicomanganese manufacturing and synthetic Potassium Titanates, were produced and investigated. Green bodies were fabricated by uni-axial compression at 35 and 196 MPa. The sinters were obtained by one-stage (1100 °C/1 h) or two-stage (800 °C/1 h and 1100 °C/1 h) thermal regimes. The best mechanical properties were achieved for conditions of 33 wt% of slag, compressed under 196 MPa and treated by the two-stage regime of sintering. Structural investigation of the processes taking place in the produced ceramic materials was carried out by scanning electron microscopy and X-ray diffraction. The resulting products were characterized by a gradient phase composition constituted by perovskite, leucite, Potassium hexatitanate, pyrophanite-ilmenite solid solutions, hollanadite-like and pyroxene-like crystalline phases as well as glassy phase of varied chemical composition. The mechanism of the sintering processes was also characterized.

  • molten salt synthesis and characterization of Potassium polytitanate ceramic precursors with varied tio2 k2o molar ratios
    Journal of the American Ceramic Society, 2008
    Co-Authors: Tomas Sanchezmonjaras, A V Gorokhovsky, J I Escalantegarcia
    Abstract:

    Semi-crystalline Potassium Titanates, useful as precursors to produce composite materials and coatings, were synthesized by thermal treatment of powdered TiO2 in molten mixtures of KNO3 and KOH at 4501–5501C. The products obtained had similar structures of laminar crystals, aggregated in particles of about 3 l mo fn 5 TiO2/K2O molar ratio in the range 2.8– 6.0. The value of n could be regulated by the temperature of synthesis, the weight ratio of [KOH]/[KNO3] in the molten salt mixture, and the number of water washing operations. The reduction of the TiO2/K2O molar ratio increased the contents of H2O in the composition of Potassium polytitanate, from 5.3 to 11.4 and from 0.2 to 8.6 (wt%) in the adsorbed and structural forms. The thermal treatment of the Potassium polytitanate precursors obtained resulted in dehydration and chemical interaction with unreacted TiO2 at 5001–7501C, amorphization at 7501–8501C, crystallization of K2Ti4O9 (in some cases K3Ti8O17 )a t 8501–10901C, and crystallization of K2Ti6O13 at temperatures 410901C. The mechanisms of the structural transformation and phase evolution were considered as a function of the TiO2/K2O molar ratio in the Potassium polytitanate.

Jongshik Chung - One of the best experts on this subject based on the ideXlab platform.

  • catalytic combustion of diesel soot over perovskite type catalyst Potassium Titanates
    Kinetics and Catalysis, 2012
    Co-Authors: Xiuhong Meng, Qiang Wang, Linhai Duan, Jongshik Chung
    Abstract:

    Potassium Titanates with a high crystallinity were successfully prepared by the sol-gel method and characterized by XRD, SEM, and BET surface area measurements. K6Ti4O11, K2Ti2O5, K2Ti4O9 were found to have better soot oxidation performance compared with Pt/TiO2 and CeO2 based catalysts. K2Ti2O5 may be an excellent candidate for soot oxidation due to its high oxidation activity, water-stability, resistance to sulfur poisoning and economical advantages. Certain amount of NOx can contribute to the catalytic combustion of diesel over Potassium Titanates, implying that K2TiO5 may be a kind of catalyst for simultaneous removal of NOx and soot.

  • formation and structural characterization of Potassium Titanates and the Potassium ion exchange property
    Materials Research Bulletin, 2009
    Co-Authors: Qiang Wang, Zhanhu Guo, Jongshik Chung
    Abstract:

    Abstract In the present work, K 2 Ti 2 O 5 , K 2 Ti 4 O 9 and K 2 Ti 6 O 13 are synthesized by solid state method. Their structures and morphologies are characterized by X-ray diffraction, Raman spectra and scanning electron microscopy. The binding energies of K, Ti and O in Potassium Titanates were then evaluated by X-ray photoelectron spectroscopy and compared with those in K/TiO 2 . Finally the corresponding K ion exchange properties are investigated by synthesizing NO oxidation catalysts with Co(NO 3 ) 2 precursor. It is found that the binding energy of K in K 2 Ti 2 O 5 is much higher than those in K 2 Ti 4 O 9 and K 2 Ti 6 O 13 , and because of which, it shows quite different catalytic performances. Compared with other Potassium Titanates, the K in K 2 Ti 2 O 5 is much easier to be exchanged out.

S X Dou - One of the best experts on this subject based on the ideXlab platform.

  • understanding the structural and chemical evolution of layered Potassium Titanates for sodium ion batteries
    Energy Storage Materials, 2020
    Co-Authors: Xiaobo Zheng, Haojie Zhu, Guoqiang Zhao, Kun Rui, Jie Shu, Xiaolin Wang, Wenping Sun, S X Dou
    Abstract:

    Abstract Layered Potassium Titanates are promising anodes for sodium ion batteries, owing to their superior cycling stability, huge abundance, and environmental benignity. The structural and chemical evolution mechanisms of layered Potassium Titanates are still not entirely clear, however, which is a huge obstacle to their practical application. Herein, we develop layered K2Ti4O9 as a model anode of Potassium Titanates for SIBs and to investigate the corresponding structural and chemical evolution during cycling process. The results demonstrate that the crystal structure of K2Ti4O9 is well maintained with the incorporation of sodium ions and a zero-strain characteristic is observed upon sodium insertion/extraction process. Furthermore, about half of the Potassium ions dissolve out of the K2Ti4O9 host structure, and equal amounts of sodium ions then occupy the vacancies created by the Potassium ions during charging/discharging processes, eventually resulting in the formation of KNaTi4O9. Density functional theory calculations further confirm the possibility of the generation of KNaTi4O9 and indicate that the intercalated sodium ions are more likely to occupy the K2 Wyckoff sites.