Catalytic effect of alkaline earth oxides on carbothermic formation of hexagonal boron nitride

Topkaya, Yavuz Ali
Effect of MgO, CaO and BaO on carbothermic formation of hexagonal boron nitride (h-BN) was investigated. B(2)O(3-)C mixtures containing alkaline earth oxide additives were reacted at 1500 degrees C for 30-120 min in nitrogen atmosphere. Formed phases in the reaction products were determined by powder-XRD analyses, and amounts of the constituents were determined by chemical analyses. Particle size and morphology of the formed h-BN powders were examined by FESEM and particle size distributions were determined by particle size analyzer. Addition of alkaline earth oxides was found to increase the amount and grain size of h-BN significantly and to decrease the amount of B(4)C formed in the system. Investigated alkaline earth oxides presented similar catalytic effects according to chemical analyses and FESEM observations. While the average particle size of h-BN powder obtained from plain mixture was 149 nm, those obtained from MgO, CaO and BaO containing mixtures were 297, 367 and 429 run, respectively. (C) 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved.


Thermoluminescence properties of Al doped ZnO nanoparticles
IŞIK, MEHMET; Hasanlı, Nızamı (Elsevier BV, 2018-08-15)
ZnO nanoparticles doped with aluminum (AZO nanoparticles) were investigated using low temperature thermoluminescence (TL) and structural characterization experiments. TL experiments were performed on AZO nanoparticles in the temperature range of 10-300 K. TL curve presented one intensive peak around 123 K and two overlapped peaks to intensive peak around 85 and 150 K for heating rate of 0.1 K/s. Curve fitting and initial rise methods were used to find the activation energies of associated trapping centers. ...
Morphology and magnetic properties of barium hexaferrite ceramics synthesized in x wt% NaCl-(100-x) wt% KCL molten salts
Aydogan, Eda; Kaya, Serap; Dericioğlu, Arcan Fehmi (Elsevier BV, 2014-01-01)
Micron size barium hexaferrite (BaFe12O19) platelets were prepared by the molten-salt synthesis method in various weight proportions of NaCl-KCl salt mixtures as a liquid medium. The effect of molten salt composition-x wt% NaCl and (100-x) wt% KCl-on the amount of barium hexaferrite phase formation, as well as, on the morphology and magnetic properties of the final products are discussed. Inductively coupled plasma-mass spectroscopy (ICP-MS) was used to determine the solubility of the starting materials in ...
Dielectric and piezoelectric properties of PZT ceramics doped with strontium and lanthanum
Kalem, Volkan; Çam, İbrahim; Timucin, Muharrem (Elsevier BV, 2011-05-01)
PZT based piezoelectric ceramics obtained by doping with various levels of Sr2+ and La3+, designated as PSLZT, were prepared by conventional processing techniques. The effects of Sr2+ and La3+ additions, and that of the Zr/Ti ratio on microstructure, on phase constitution, and on the dielectric and piezoelectric properties were investigated. XRD data revealed that all PSLZT compositions had perovskite structure in which increasing Sr and/or decreasing Zr/Ti ratio increased the tetragonality. In PSLZT cerami...
Evolution of magnetic and structural properties of TiO2 with Co-doping
Topal, Ugur; Ozkan, Husnu; Bakan, Halil I.; Cankur, Oktay; Topal, Kevser (Elsevier BV, 2008-03-15)
This paper presents the phase formations and magnetic properties of Co-doped TiO2 synthesized by the colloidal and ammonium nitrate melt techniques (ANMT). The phase formations and ferromagnetic properties were studied with XRD and SQUID magnetometry. Crystallization of the TiO2 rutile lattice was completed at 1000 degrees C and that was preserved during annealing up to 1300 degrees C. For the samples annealed at 1200 degrees C, elemental analysis has shown that the colloidal technique leads to a single-pha...
Synthesis of New Thienylene Pyrrole Monomers and Their Electropolymerizations
Eken, Serap; Carbas, Buket Bezgin; Akdağ, Akın; Önal, Ahmet Muhtar (The Electrochemical Society, 2014-01-01)
In this study, four new 2,5-dithienylpyrroles (SNS) 1-(3-fluoro-phenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole (m-FPTP), 1-(3-chlorophenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole (m-ClPTP), 1-(3-bromo-phenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole (m-BrPTP) and 1-(4-bromo-phenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole (p-BrPTP) containing meta and para substituted benzene ring at the nitrogen atom were synthesized via Paal-Knorr condensation of 1,4-di(2-thienyl)-1,4-butanedione with corresponding halo-substituted anilines. The mon...
Citation Formats
H. E. ÇAMURLU, Y. A. Topkaya, and N. SEVİNÇ, “Catalytic effect of alkaline earth oxides on carbothermic formation of hexagonal boron nitride,” CERAMICS INTERNATIONAL, pp. 2271–2275, 2009, Accessed: 00, 2020. [Online]. Available: