Using sol-gel method,we prepared ferroelectric PbTiO_(3) fine particles with particle size covering the range 20-200nm;the dielectric properties of powder compact were studied in the present work.The room temperature ...Using sol-gel method,we prepared ferroelectric PbTiO_(3) fine particles with particle size covering the range 20-200nm;the dielectric properties of powder compact were studied in the present work.The room temperature dielectric constant increases with the decrease in particle size and reaches a maximum value at the size of about 40nm.The temperature dependence of dielectric constant involving the evolution of particle size during the measurement is discussed.展开更多
The surface effects on the spontaneous polarization in ferroelectric thin films were discussed based on the Ising model in a transverse field.Both the modifications of the transverse field and the strength of coupling...The surface effects on the spontaneous polarization in ferroelectric thin films were discussed based on the Ising model in a transverse field.Both the modifications of the transverse field and the strength of coupling in the surface layer were taken into consideration.At the temperature much lower than the Curie point,the behaviour of the spontaneous polarization deviates from the phenomenological description.The surface effects might lead to the spontaneous polarization and the Curie temperature changing in different direction.The theory gives a reasonable description of the experimental temperature dependence of the spontaneous polarization of triglycine sulfate thin films in the literature.展开更多
The profilc of susceptibility uear the surfuce of a senni-ifinite frrclectric is calculatel from Luidau free energy.In surfunce ferroclectric plase,the susceptibility is reduced at surface for|δ|<<βand much en...The profilc of susceptibility uear the surfuce of a senni-ifinite frrclectric is calculatel from Luidau free energy.In surfunce ferroclectric plase,the susceptibility is reduced at surface for|δ|<<βand much enhanced for|δ|-β,whereδandβare the.extrapolation le1ngth and tle coluerent lengtl respectiv:ly.In ferroelectric phase,the surface susceptibility is gcllcrally reduced for8<0.But the crurve is not molnotonic,there is a mininum in the surface layer.Forδ>0,the surface susceptibility is.redced forδ<<βand enhanced fo rδ-β.The curve has a maxiln11 in the srface layer.展开更多
文摘Using sol-gel method,we prepared ferroelectric PbTiO_(3) fine particles with particle size covering the range 20-200nm;the dielectric properties of powder compact were studied in the present work.The room temperature dielectric constant increases with the decrease in particle size and reaches a maximum value at the size of about 40nm.The temperature dependence of dielectric constant involving the evolution of particle size during the measurement is discussed.
文摘The surface effects on the spontaneous polarization in ferroelectric thin films were discussed based on the Ising model in a transverse field.Both the modifications of the transverse field and the strength of coupling in the surface layer were taken into consideration.At the temperature much lower than the Curie point,the behaviour of the spontaneous polarization deviates from the phenomenological description.The surface effects might lead to the spontaneous polarization and the Curie temperature changing in different direction.The theory gives a reasonable description of the experimental temperature dependence of the spontaneous polarization of triglycine sulfate thin films in the literature.
文摘The profilc of susceptibility uear the surfuce of a senni-ifinite frrclectric is calculatel from Luidau free energy.In surfunce ferroclectric plase,the susceptibility is reduced at surface for|δ|<<βand much enhanced for|δ|-β,whereδandβare the.extrapolation le1ngth and tle coluerent lengtl respectiv:ly.In ferroelectric phase,the surface susceptibility is gcllcrally reduced for8<0.But the crurve is not molnotonic,there is a mininum in the surface layer.Forδ>0,the surface susceptibility is.redced forδ<<βand enhanced fo rδ-β.The curve has a maxiln11 in the srface layer.
