Fabrication And Research On Properties Materials Of The Strontium Barium Niobate Ceramic

According to the latest development and shortcoming of the ceramics of niobate,the e?ects of the glass additives, oxide replacement and fabrication methods on struc-ture, sintering, phase compositions, dielectric properties were investigated by usingthe Di?erential thermal analysis (DTA), X-ray di?raction (XRD), Scanning electronmicroscope (SEM) and AC impedance. The results showed as the following:The in?uence of titanium dioxide and sintering on the phase compositions anddielectric properties were investigated. The peak of SBT was not observed in the graphof XRD when the y value was no more than 0.1 and the phase of SBT was melted in thephase of SBN. The peaks of SBT and SBN were observed at the same time when they value was no less than 0.2 and they are coexisting. The density of SBTN ceramicsincreased with the increasing of temperature when the sintering temperature below1300℃. When the temperature was higher than 1300℃, the density of samples thatthe y value equals to 0 and 0.1 decreased with the rising of temperature and the samplesthat the y value equals to 0.2 and 0.3 were increased. The max dielectric constant ofceramics was 11798 when the y value equals to 0.1. The in?uence of La³⁺ and Ce⁴⁺ onthe ceramics of SBTN was investigated. The ion of Nb5+ was replaced by La³⁺ resultsin the hollow of structure and the crystal distance's minishing. The doping of Ce⁴⁺ wascomplex and made no in?uence to crystal parameter. The relative densities of samplesdoped by La³⁺ and Ce⁴⁺ decreased, the dielectric constant and loss decreased and thestabilization of dielectric constant increased.The e?ects of alkali on the phase transitions, dielectric properties of strontiumbarium niobate were discussed. The Sr²⁺ and Ba²⁺ in position A of tungsten bronze canbe replaced by Ca²⁺ and the position C can be filled by Mg²⁺. The size of the particle ofceramics with Ca and Mg doped sintered at 1300℃grew bigger. The Curie temperatureof the ceramics doped with Ca came out at 150℃and 330℃which corresponding to SBNand (Sr,Ba,Ca)Nb2O6 respectively. The Curie peak disappeared when the amountof Ca doped increased step by step. The Curie temperature of the ceramics dopedwith Mg came out at 150℃and 310℃.The two peaks combined and moved to lowtemperature with the increasing of Mg doped.The co-fired ceramics of low-melting material and strontium barium niobate wereput forward for the first time. As the result of the crystal of strontium barium nio-bate can be enwrapped by the low-melting material what can form the structure of"shell-core"in the sintering, the properties of strontium barium niobate ceramics canbe improved. The SBN ceramics of CBS glass doped were formed at 1100℃and noother phase was observed, which can reduce the sintering temperature. The Curie temperature and the dielectric constant of SBN ceramics decreased and then increasedwith the increasing of CBS glass.The phase of CaNbO3 came out when the amount of CBS doped was more than 8mol%, which made serious e?ects on dielectric properties. Strontium barium niobatepowder, Sr0.5Ba0.5Nb2O6 (SBN50), has been fabricated for the first time by high-energyball milling on a mixture of Nb2O5, BaCO3 and SrCO3. SBN50 ceramics have beenobtained by sintering the green compacts derived from milled 30 h powder mixturewithout calcining at 1250, 1280, 1300 and 1350℃for 1.5-12 h. The phase and mi-crostructure evolution of the samples were characterized by X-ray di?raction and scan-ning electron microscopy. The properties of SBN50 ceramics were also measured. Theresults show that the single phase SBN50 formed at 1100℃and the dielectric constantfirstly increases and then decreases with the rising of sintering temperature and soakingtime. The grain size of the sintered samples in di?erent conditions changed regularly.Highest dielectric constant (εmax=1147) at 1 kHz frequency has been obtained forthe pellet sintered at 1300℃for 3 h.The Curie Temperature (Tc) is 130℃.