Dipoles with Lorentz-type resonant electromagnetic responses can realise negative effective parameters in their negative resonant region.The electric dipole and magnetic dipole can realise,respectively,negative permittivity and negative permeability,so both the field distribution forms of electric and magnetic dipoles are fundamentals in designing left-handed metamaterial.Based on this principle,this paper studies the field distribution in high-permittivity dielectric materials.The field distributions at different resonant modes are analysed based on the dielectric resonator theory.The origination and influence factors of the electric and magnetic dipoles are confirmed.Numerical simulations indicate that by combining dielectric cubes with different sizes,the electric resonance frequency and magnetic resonance frequency can be superposed.Finally,experiments are carried out to verify the feasibility of all-dielectric left-handed metamaterial composed by this means.
The piezoelectric,dielectric,and ferroelectric properties of the(LiCe) co-substituted calcium bismuth niobate(CaBi2Nb2O9,CBNO) are investigated.The piezoelectric properties of CBNO ceramics are significantly enhanced and the dielectric loss tan δ decreased.This makes poling using(LiCe) co-substitution easier.The ceramics(where represents A-site Ca2+ vacancies,possess a pure layered structure phase and no other phases can be found.The Ca0.88(LiCe)0.04 0.04Bi2Nb2O9 ceramics possess optimal piezoelectric properties,with piezoelectric coefficient(d 33) and Curie temperature(TC) found to be 13.3 pC/N and 960 C,respectively.The dielectric and piezoelectric properties of the(LiCe) co-substituted CBNO ceramics exhibit very stable temperature behaviours.This demonstrates that the CBNO ceramics are a promising candidate for ultrahigh temperature applications.
