Bond characteristics and microwave dielectric properties of (Li0.5Ga0.5)(2+) doped Mg2Al4Si5O18 ceramics
CERAMICS INTERNATIONAL
Authors: Lou, Weichao; Song, Kaixin; Hussain, Fayaz; Liu, Bing; Bafrooei, Hadi Barzegar; Lin, Huixin; Su, Weitao; Shi, Feng; Wang, Dawei
Abstract
Cordierite ceramic is one kind of important electronic materials for radio frequency circuit. In this work, Mg2-x(Li0.5Ga0.5)(x)Al4Si5O18 (0 <= x <= 0.1) ceramics with pure cordierite phase, were successfully synthesized via the traditional solid state reaction method. The dependence of microwave dielectric properties on the crystal structure was analyzed in detail by the complex chemical bond theory (P-V-L theory) and classical dielectric polarizability theory. The dielectric constant (epsilon(r)) was mainly related to the density, bond ionicity and ionic polarizability of Mg2-x (Li0.5Ga0.5)(x)Al4Si5O18 ceramics. The quality factor (Q x f) was in relationship to the lattice energy, atomic packing fraction and centrosyrnmetry of [Si4Al2O18] hexagonal ring in cordierite crystal structure. The temperature coefficient of resonant frequency (tau(f)) value was dominated by the bond energy and distortions of [MgO6] octahedron. The maximum values of Q x f = 50,560 GHz and epsilon(r) = 4.72 were obtained for undoped Mg2Al4Si5O18 and Mg1.98Li0.01Ga0.01Al4Si5O18, respectively.
Stability and convergence of multistep schemes for 1D and 2D fractional model with nonlinear source term
APPLIED MATHEMATICAL MODELLING
Authors: Maurya, Rahul Kumar; Devi, Vinita; Singh, Vineet Kumar
Abstract
Stable multistep schemes based on Caputo fractional derivative approximation are pre-sented for solving 1D and 2D nonlinear fractional model arising from dielectric media. We approximate Caputo fractional derivatives in time with a multistep scheme of order O(tau(3-alpha)) & O(tau(3-beta)), 1 < beta
COA
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