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The main points are: Linear and Nonlinear Dielectric Ceramics, Permittivity of Dielectric, Electric Loss Factor, Electrical Susceptibility, Dielectric Constant Contribution, Type of Mechanisms, Observed Value, Electrical Circuit
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he dielectric c ns for each re m diameter an F and a dissip ermittivity of Electric loss fa Electrical susc s an atomic ra ctric constant rved value is behavior. cm thick die rials if used at wing are two
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lectric materi t 100 Hz and electrical circ
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a. With the help of arrows, sketch on the same figure the resulting movement of S atoms keeping the Zn atoms fixed. S atoms form the coordination tetrahedra around Zn atoms located at ¼ ¼ ¼. Have the coordinates of the centre of mass (and thus centre of charge) of S atoms changed? b. In what direction, must the Zn atom move to remain equidistant from the coordinating S atoms? Would it still be at the centre of charge of the S atoms? c. If the Zn–S bond is ionic, or partially ionic, in what direction will the dipole moment develop? d. At the charge-centre of a tetrahedron of S atoms around Zn in the unstressed crystal, what charge due to S must appear? Express the value in terms of charge of one S atom (-q). e. Experimental evidence shows relatively large covalent character of Zn-S bonds in ZnS structures modifies the the magnitude of the charge on each S and Zn ‘ion’ to |q| ≈ 0.26. e where e denotes the electronic charge. Experimentally the displacement (Δ l ) of the Zn ion from the centre of the tetrahedron is 75 fm when τ = 25 MPa. Calculate the electric polarization, P and piezoelectric coefficient, d?