Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Irreversible Changes in Amorphous C3n4 Under Pressure: Loss of Chemical Order and Graphite-Like Character(Taylor & Francis Ltd, 2025-04-03) Durandurdu, MuratThe high-pressure behavior of triazine-based amorphous C3N4, initially exhibiting a chemically ordered, graphite-like structure, was investigated using ab initio molecular dynamics simulations. Our study reveals a pressure-induced transition to a high-density amorphous (HDA) phase characterized by increased coordination number for carbon (3.88) and nitrogen (2.93) atoms. This transition occurs gradually over a broad pressure range, initiated by the breakdown of chemical ordering and the formation of homopolar C-C and N-N bonds, which persist in both the HDA and recovered phases. The recovered phase retains elevated coordination numbers (C: 3.25, N: 2.46) but loses its initial graphite-like topology, evolving into a three-dimensional network structure. Electronic structure analysis reveals semiconducting behavior in the HDA phase and n-type semiconductor characteristics in the recovered phase.Article Citation - WoS: 7Citation - Scopus: 7Amorphous Boron Nitride at High Pressure(Taylor & Francis Ltd, 2016-05-18) Durandurdu, MuratThe pressure-induced phase transformation in hexagonal boron nitrite and amorphous boron nitrite is studied using ab initio molecular dynamics simulations. The hexagonal-to-wurtzite phase transformation is successfully reproduced in the simulation with a transformation mechanism similar to one suggested in experiment. Amorphous boron nitrite, on the other hand, gradually transforms to a high-density amorphous phase with the application of pressure. This phase transformation is irreversible because a densified amorphous state having both sp(3) and sp(2) bonds is recovered upon pressure release. The high-density amorphous state mainly consists of sp(3) bonds and its local structure is quite similar to recently proposed intermediate boron nitrite phases, in particular tetragonal structure (P4(2)/mnm), rather than the known the wurtzite or cubic boron nitrite due to the existence of four membered rings and edge sharing connectivity. On the basis of this finding we propose that amorphous boron nitrite might be best candidate as a starting structure to synthesize the intermediate phase(s) at high pressure and temperature (probably below 800 degrees C) conditions.