Overview

Current research in my group is focussed on exploring the cooperative phenomena in phase transitions. When cooperativity is established, atoms or molecules in the whole system act concertedly such that the system, it its entirety, is driven in a specific direction leading to a transition. Many of the phase transitions remain poorly understood due to lack of recognition of the underlying cooperative phenomena. Recently we have shown that ordering transition in Ni₃Fe alloy is caused by cooperative freezing of the L12 ordered domains at the critical temperature and the resulting propagation of the domains upon further cooling. A practical manifestation of this cooperative freezing is the critical slowing down, i.e., a significant increase in equilibration time (to 40 days or more) during annealing of Ni₃Fe alloy as the critical temperature (500 ℃) is approached. Another important class of transitions are those responsible for formation of tetrahedral amorphous materials. We found that cooperative relaxation of the tetrahedral network transforms supercooled water into stacking disordered ice, also known as low density amorphous (or LDA) ice. A similar transition is also found in supercooled silicon that leads to formation of amorphous silicon which is commonly used in solar cells. A related research activity in my group is the investigation of structural changes in tetrahedral materials based on ring based mesostructures. We have proposed and implemented a method to identify the rings with specific shapes using puckering method which was originally developed (about five decades ago) to analyse organic ring compounds. With this method, we have been able to identify the boat and chair shaped six-membered rings. Such rings form the basis of mesostructures that are commonly found in tetrahedral materials. Using this approach, we have introduced a new method to identify hexagonal crystalline particles in amorphous materials. We have also explored ring based defect structures such as pentagonal nanochannels which, potentially, have a profound influence on the bulk properties of amorphous ice. Apart from these theoretical and computational approaches, we have also recently started experimental work to understand ionic equilibria in problems of practical interest. In particular, we are working on CO₂ absorption in aqueous potassium carbonate and amine solutions with small amounts of added promoters. Such absorption processes are commonly employed in fertilizer industry. Our aim is to understand the ionic equilibria responsible for enhancement of absorption rates due to added promoters such as glycine. In collaboration with the heterogeneous catalysis group (Prof. Goutam Deo), we are also exploring the use of Alumina supported Ni₃Fe as a catalyst for CO₂ methanation reaction.

Awards

• Gold Medal, B. Tech., Nagpur University (1998).
• Outstanding graduate student award for academic achievement, OSU Department of Chemical Engineering (2005).

Recent Publications

• Jitendra Kumar Prabhakar, Pankaj A. Apte and Goutam Deo, "The kinetics of Ni/Al₂O₃ and Ni-Fe/Al₂O₃ catalysts for the CO₂ methanation reaction and the reasons for promotion", Chemical Engineering Journal (2023) 144252.
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• Anil Mangla, Goutam Deo, Pankaj A. Apte, "Cooperative freezing of the L12 ordered domains at the critical cooling temperature of Ni₃Fe alloy", Journal of Statistical Mechanics: Theory and Experiment (2022) 093204.
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• Nandlal Pingua and P. A. Apte, "Topological Identification Criteria, Stability, and Relevance of Pentagonal Nanochannels in Amorphous Ice", Journal of Physical Chemistry B, 123 (2019) 10301.
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• Nandlal Pingua and P. A. Apte, "Increase in local crystalline order across the limit of stability leads to cubic-hexagonal stacking in supercooled monatomic (mW) water", Journal of Chemical Physics 149 (2018), 074506
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• Anil Mangla, Goutam Deo, and P. A. Apte, "NiFe local ordering in segregated Ni3Fe alloys: A simulation study using Angular Dependent Potential", Computational Materials Science 153C (2018), 449-460.
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• A. K. Gautam, Nandlal Pingua, Aashish Goyal, and P. A. Apte, "Dynamical instability causes the demise of a supercooled tetrahedral liquid", Journal of Statistical Physics 168 (2017), 1302-1318.
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• P. A. Apte, N. Pingua, A. K. Gautam, Uday Kumar, S. Y. Willow, X. C. Zeng, and B. D. Kulkarni, "The freezing tendency towards 4-coordinated amorphous network causes increase in heat capacity of supercooled Stillinger-Weber silicon" RSC Advances 5 (2015), 44679-44686.
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• J. Wang, P. A. Apte, J. Morris, X. C. Zeng, "Freezing Point and Solid-Liquid Interfacial Free Energy of Stockmayer Dipolar Fluids: A Molecular Dynamics Simulation Study", Journal of Chemical Physics, 139 (2013), 114705.
• P. A. Apte and A. K. Gautam, "Nonmonotonic dependence of the absolute entropy on temperature in supercooled Stillinger-Weber silicon", Journal of Statistical Physics, 149 (2012), 551-567, 2012.
• P. A. Apte, "Efficient computation of free energy of crystal phases due to external potentials by error-biased Bennett acceptance ratio method", Journal of Chemical Physics, 132 (2010), 084101.
• P. A. Apte and X. C. Zeng, "Anisotropy of crystal-melt interfacial free energy of silicon by simulation", Appl. Phys. Lett., 92 (2008), 221903.
• P. A. Apte and I. Kusaka, "Direct calculation of solid-vapor coexistence points by thermodynamic integration: Application to single component and binary systems", Journal of Chemical Physics, 124 (2006), 184106.
• P. A. Apte and I. Kusaka, "Evaluation of translational free energy in a melting temperature calculation by simulation", Physical Review E, 73 (2006), 016704.
• P. A. Apte and I. Kusaka, "Direct calculation of solid-liquid coexistence points of a binary mixture by thermodynamic integration", Journal of Chemical Physics, 123 (2005), 194503.
• P. A. Apte and I. Kusaka, "Bubble nucleation in micellar solution: A density functional study", Journal of Chemical Physics, 121 (2004), 12532.