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Bhaskar U.K.,Sreegopal Banerjee College | Bid S.,Academy of Technology | Pradhan S.K.,University of Burdwan
Journal of Alloys and Compounds | Year: 2011

Nanocrystalline stoichiometric Ti0.9Al0.1N powder has been prepared by ball-milling the α-Ti (hcp) and aluminum (fcc) powders under N2 at room temperature. Initially, α-Ti phase partially transformed to the transient cubic β-Ti phase and Ti0.9Al 0.1N (fcc) phase is noticed to form after 3 h of milling. Nanocrystalline stoichiometric Ti0.9Al0.1N phase is formed after 7 h of milling. After 1 h of milling, all Al atoms are diffused into the α-Ti matrix. The transient β-Ti phase is noticed to form after 1 h of milling and disappears completely after 7 h of milling. Microstructure characterization of unmilled and ball-milled powders by analyzing XRD patterns employing the Rietveld structure refinement reveals the inclusion of Al and nitrogen atoms into the Ti lattice on the way to formation of Ti 0.9Al0.1N phase. Microstructure of ball-milled samples is also characterized by HRTEM. The particle size of Ti0.9Al 0.1N phase, as obtained from XRD method, is ∼5 nm which is very close to that obtained from HRTEM. © 2010 Elsevier B.V. All rights reserved.


Bhaskar U.K.,Sreegopal Banerjee College | Satpati B.,Saha Institute of Nuclear Physics | Pradhan S.K.,University of Burdwan
Powder Technology | Year: 2013

The nanostructured (Ti0.9Si0.1)N powder has been mechanosynthesized by ball-milling the elemental stoichiometric mixture of α-Ti(0.9mol fraction) and Si (0.1mol fraction) powders at room temperature under nitrogen atmosphere. After 1h of milling, the α-Ti (hcp) phase partially transformed to metastable β-Ti (cubic) phase and the initiation of (Ti0.9Si0.1)N (fcc) phase is noticed. Completely stoichiometric nanocrystalline (Ti0.9Si0.1)N phase is obtained after 7h of milling. Microstructure of unmilled and ball-milled powders is characterized by analyzing their XRD patterns employing the Rietveld structure refinement method and by HRTEM images. The analysis reveals the inclusion of Si and nitrogen atoms into the Ti lattice on the way to formation of (Ti0.9Si0.1)N phase. Presence of Si and nitrogen in the ball milled powders is also confirmed from EDX spectra. The average size of almost monodispersed spherical particles of (Ti0.9Si0.1)N is ~4nm. Optical band gaps of TiN and TiSiN powders are measured from UV-vis absorption spectra and it has been found that the optical band gap of highly insulating TiN nanoparticles (band gap ~5.56eV) can be substantially reduced towards semiconductors (band gap ~3.96eV) by incorporating a small amount of Si into TiN matrix. © 2013 Elsevier B.V.


Bhaskar U.K.,Sreegopal Banerjee College | Pradhan S.K.,University of Burdwan
Materials Science and Engineering A | Year: 2012

The nanostructured Ti 0.9C 0.1N has been prepared by ball-milling the elemental stoichiometric powder mixture of Ti and graphite under nitrogen at room temperature. Within 1h of milling, the α-Ti (hcp) phase partially transformed to metastable β-Ti (cubic) phase and initiation of Ti 0.9C 0.1N (fcc) phase is noticed. Completely stoichiometric nanocrystalline Ti 0.9C 0.1N phase is obtained after 5h of milling. Microstructure characterization of unmilled and all ball-milled powders is made by analyzing their XRD patterns employing the Rietveld structure refinement method. The analysis reveals the inclusion of C and nitrogen atoms into the Ti lattice on the way to formation of Ti 0.9C 0.1N phase. The inclusion of C and nitrogen atoms in the α-Ti lattice is also confirmed by EDX. The microstructure of ball-milled samples is also characterized by HRTEM. The average size of almost monodispersed spherical particles of Ti 0.9C 0.1N is ~4nm which corroborates the finding of the Rietveld analysis. © 2011 Elsevier B.V..


Bhaskar U.K.,Sreegopal Banerjee College | Pradhan S.K.,University of Burdwan
Materials Research Bulletin | Year: 2013

Nanocrystalline stoichiometric Ti0.7Ni0.3N powder has been synthesized by ball-milling the α-Ti (hcp) and Ni (fcc) powders under N2 gas at room temperature. The α-Ti phase partially transforms to the transient (-Ti phase after 1 h of milling. After 5.5 h of milling, very broad reflections of Ti0.7Ni0.3N phase is noticed. Complete formation of Ti0.7Ni0.3N phase is observed after 9 h of milling. Microstructure in terms of lattice imperfections of unmilled and all ball-milled powder mixtures are primarily characterized by analyzing the X-ray powder diffraction patterns employing the Rietveld structure refinement procedure. It clearly reveals the presence of Ti 0.7Ni0.3N phase and inclusion of nitrogen atoms into the α-Ti-Ni matrix on the way to formation of nitride phase. Microstructure of the ball milled nitride powders is also characterized by HRTEM. Particle size of Ti0.7Ni0.3N phase obtained from XRD method of characterization is ∼5 nm which is very close to that obtained from HRTEM. © 2013 Elsevier Ltd. All rights reserved.


Bhaskar U.K.,Sreegopal Banerjee College | Bid S.,Academy of Technology | Satpati B.,CSIR - Institute of Minerals And Materials Technology | Pradhan S.K.,University of Burdwan
Journal of Alloys and Compounds | Year: 2010

Nanocrystalline stoichiometric TiN powder has been prepared by ball-milling the α-Ti powder under N2 gas at room temperature. The α-Ti phase is partially transformed to the transient β-Ti phase and TiN phase is noticed to form after 3 h of milling and nanocrystalline TiN phase is formed after 9 h of milling. Microstructure characterization of unmilled and ball-milled samples characterized primarily by X-ray diffraction employing the Rietveld structure refinement clearly reveals the presence of TiN phase and inclusion of nitrogen atoms in the α-Ti lattice in the way to formation of nitride phase. Transmission electron microscopy image confirms the presence of TiN phase and the size of TiN particles obtained from both XRD and TEM methods of characterization are very close in value (∼13 nm). © 2009 Elsevier B.V. All rights reserved.

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