（1-x）（K0.47sNa0.475Li0.os）（Nb0.sTa0.2）O3-xBiCoO3 （KNLNT-BC） lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method. Effects of the BC content on the phase structure, mi...（1-x）（K0.47sNa0.475Li0.os）（Nb0.sTa0.2）O3-xBiCoO3 （KNLNT-BC） lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method. Effects of the BC content on the phase structure, microstructure and electrical properties of KNLNT-BC ceramics were investigated. XRD patterns reveal that all the ceramic samples are in the pure perovskite-type structure, and the phase structure changes from the tetragonal to pseudo-cubic phase with the increase of the BC content. After the substitution of BC, the grain size is significantly reduced and relaxer behaviors are induced. By adding a small amount of BC to KNLNT ceramics, piezoelectric properties are improved, while further addition of BC makes the piezoelectric properties deteriorate markedly. The optimized electrical properties atx= 0.005 are as follows： d33 = 194 pC/N, kp = 0.44.展开更多
It is usually difficult to design a high performance Sigma⁃Delta(ΣΔ)modulator due to system noises.In this paper,a disturbance observer(DOB)is utilized to estimate the system noises and eliminate their effects on Σ...It is usually difficult to design a high performance Sigma⁃Delta(ΣΔ)modulator due to system noises.In this paper,a disturbance observer(DOB)is utilized to estimate the system noises and eliminate their effects on ΣΔ modulators.The applied DOB is introduced with a Bode's ideal cut⁃off(BICO)filter used for the Q⁃filter.The proposed DOB with the BICO filter used in ΣΔ modulators can achieve better noise⁃shaping ability,resulting from the less phase loss of the BICO filter.Finally,the simulation results show that the proposed BICO filter scheme is a useful additional tool for improving the performance of ΣΔ modulators.展开更多
文摘（1-x）（K0.47sNa0.475Li0.os）（Nb0.sTa0.2）O3-xBiCoO3 （KNLNT-BC） lead-free piezoelectric ceramics were prepared by the conventional solid-state sintering method. Effects of the BC content on the phase structure, microstructure and electrical properties of KNLNT-BC ceramics were investigated. XRD patterns reveal that all the ceramic samples are in the pure perovskite-type structure, and the phase structure changes from the tetragonal to pseudo-cubic phase with the increase of the BC content. After the substitution of BC, the grain size is significantly reduced and relaxer behaviors are induced. By adding a small amount of BC to KNLNT ceramics, piezoelectric properties are improved, while further addition of BC makes the piezoelectric properties deteriorate markedly. The optimized electrical properties atx= 0.005 are as follows： d33 = 194 pC/N, kp = 0.44.
基金Sponsored by the Top Scientific and Technological Innovation Team from Beijing University of Chemical Technology(Grant No.BUCTYLKJCX06)
文摘It is usually difficult to design a high performance Sigma⁃Delta(ΣΔ)modulator due to system noises.In this paper,a disturbance observer(DOB)is utilized to estimate the system noises and eliminate their effects on ΣΔ modulators.The applied DOB is introduced with a Bode's ideal cut⁃off(BICO)filter used for the Q⁃filter.The proposed DOB with the BICO filter used in ΣΔ modulators can achieve better noise⁃shaping ability,resulting from the less phase loss of the BICO filter.Finally,the simulation results show that the proposed BICO filter scheme is a useful additional tool for improving the performance of ΣΔ modulators.
