Articles written in Bulletin of Materials Science

    • Carrier concentration effect and other structure-related parameters on lattice thermal conductivity of Si nanowires


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      Lattice thermal conductivity (LTC) of Si bulk and nanowires (NWs) with diameter 22, 37, 50, 56, 98 and 115 nm was investigated in the temperature range 3–300 K using a modified Callaway model that contains both longitudinal and transverse modes. Using proper equations, mean bond length, lattice parameter, unit cell volume, mass density, melting temperature, longitudinal and transverse Debye temperature and group velocity for all transverse and longitudinal modes were calculated for each NW diameter mentioned. Surface roughness, Gruneisen parameter and impurity were used as adjustable parameters to fit theoretical results with experimental curves. In addition, values of electron concentration and dislocation density were determined. There are some phonon scattering mechanisms assumed, which are Umklapp and normal processes, imperfections, phonon confinement, NW boundaries, electrons scattering and dislocation. Dislocationdensity less than 10$^{14}$ m$^{−2}$ for NWs and 10$^{12}$ m$^{−2}$ for bulk has no effect on LTC. Also, electron concentration less than 10$^{22}$ m$^{−3}$ for NWs and 10$^{16}$ m$^{−3}$ for the bulk has no effect. On increasing dislocation density and electron concentration, LTC comparably decreases.

    • Temperature-dependence calculation of lattice thermal conductivity and related parameters for the zinc blende and wurtzite structures of InAs nanowires


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      Theoretical calculations are performed on lattice thermal conductivity (LTC) and related parameters for the zinc blende and wurtzite structure of InAs nanowires (NWs) with diameters of 50, 63, 66, 100 and 148 nm through the Morelli–Callaway model. For the model to be efficiently applicable, the longitudinal and transverse modes are considered. The melting point of the various-sized NWs is considered to estimate the Debye and phonon group velocities. The impacts of Grüneisen parameter, dislocations and surface roughness are also successfully utilized to address the calculated and measured LTC of the semiconductor under investigation. Results show that the Grüneisen parameter increases with decreasing NW diameter and that phonon confinement leads to an observable deviation of the calculated LTC curve from that of the experimental one in the case of bulk InAs. We assume that NW boundaries, dislocations and imperfections are responsible for the scattering of phonons along with electrons and other phonons because of normal and Umklapp processes. Therefore, at a specified temperature, LTC depends on the size and crystal structure of the semiconductor. As such, the thermal and mechanicalparameters of InAs can be greatly modified by decreasing the size and dimension of the semiconductor as a result of the quantum-confinement effect.

    • Hydrostatic pressure effects on the processes of lattice thermal conductivity of bulk Silicon and nanowires


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      The lattice thermal conductivity (LTC) of silicon nanowires (NWs) with diameters of 115, 56, 37 and 22 nm in the temperature range of 2–300 K for different pressures ranging from 0 to 10 GPa, was calculated by employing a modified Callaway model. Both longitudinal and transverse modes were explicitly considered within the model. A strategy is utilized to calculate the Debye and phonon group velocity in addition to the bulk modulus and it is derivative for different NW diameters from their related melting temperature under different pressures. The influence of the Gruneisen parameter, surface roughness and dislocation as structurally dependent parameters are successfully exploited to correlate the calculated values of LTC to that of the experimentally measured curves at various pressures including zero. The respective application of the Murnghan and Clapeyron equations for pressure-dependent lattice volume and melting temperature in the Callaway model produces results that tend to be systematically applicable by this model. The confinement and size effects of phonons and the role of pressure in the reduction of LTC are investigated. The peak value of LTC decreases with the increase of pressure for both bulk and its nanowires.

  • Bulletin of Materials Science | News

    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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