發(fā)布時(shí)間：2018-07-26 11:19

【摘要】：本文采用傳統(tǒng)固相合成法,系統(tǒng)地研究了以Li3Mg2NbO6和Li2TiO3為代表的巖鹽結(jié)構(gòu)體系的微波介質(zhì)陶瓷,實(shí)驗(yàn)結(jié)果表明相組成及摻雜對(duì)其微波介電性能產(chǎn)生較大的影響。本文研究了Zn2+對(duì)Li3Mg2NbO6微波介質(zhì)陶瓷的摻雜改性,通過(guò)改變Zn2+不同摻雜量確定了最佳配方。由于摻雜離子Zn2+的半徑比Mg2+略大,導(dǎo)致Li3Mg2NbO6陶瓷的晶格發(fā)生畸變,從而促進(jìn)了Q×f值的極大提高,同時(shí)還略微降低了該體系的燒結(jié)溫度。當(dāng)Zn2+的摻雜量為8mo1%,陶瓷樣品在1120℃燒結(jié)獲得了最好的微波介電性能：εr=17.2,Q×f=142331GHz,τf=23.2ppm/℃C。在此基礎(chǔ)上添加0.5wt%低燒助劑0.17Li2O-0.83V2O5后,其可在925℃燒結(jié)得到較好的微波介電性能：εr =14,Q×f=83395GHz,τf=-37.2ppm/℃。于此同時(shí),該低燒樣品又與Ag電極具有良好的化學(xué)兼容性�；谏鲜鰧�(shí)驗(yàn)結(jié)果,由于Li3(Mg0.92Zn0.08)2NbO6陶瓷的諧振頻率溫度系數(shù)τf仍然較負(fù),本文進(jìn)一步研究了添加Ba3(VO4)2對(duì)其微波介電性能和燒結(jié)溫度的影響。XRD結(jié)果表明在全組成范圍內(nèi),由于Li3(Mg0.92Zn0.08)2NbO6與Ba3(VO4)2的晶體結(jié)構(gòu)不同,使二者形成了復(fù)相陶瓷。由于Ba3(VO4)2較低的介電常數(shù)和Q×f值以及正的τf值,導(dǎo)致該體系的介電常數(shù)εr和Q×f值均降低,而諧振頻率溫度系數(shù)τf的符號(hào)向正方向偏移。同時(shí)由于Ba3(VO4)2的加入,引起部分V5+擴(kuò)散至基體主晶相中,從而明顯降低了體系的燒結(jié)溫度。當(dāng)添加30vol%的Ba3(VO4)2在950℃燒結(jié)后,其微波介電性能：εr:16.3,Q×f=50084GHz,τf=1.5ppm/℃。同時(shí),該復(fù)相體系與Ag電極也具有很好的化學(xué)兼容性。另外,本文還系統(tǒng)地研究了(Al0.5Nb0.5)4+摻雜取代對(duì)Li2TiO3陶瓷微結(jié)構(gòu)和微波介電性能的影響。實(shí)驗(yàn)結(jié)果表明Al3+和Nb5+的共取代對(duì)Li2TiO3的微觀形貌產(chǎn)生了明顯的影響。微裂紋的消除和晶粒的長(zhǎng)大是其Q×f值提高的主要原因。在固溶體組成范圍內(nèi),介電常數(shù)εr和τf的降低分別歸因于離子極化和晶胞體積的變化。當(dāng)(Al0.5Nb0.5)4+摻雜量為15mol%時(shí),陶瓷樣品在1150℃燒結(jié)取得了最佳的微波介電性能：εr=21.2,Q×f=181800GHz,τf=12.8ppm/℃。當(dāng)加入6wt%的BaCu(B2O5)后,樣品的燒結(jié)溫度可明顯降低至950℃,同時(shí)也兼具較優(yōu)異的微波介電性能：εr=20.4,Q×f=53290GHz,τf=3.6ppm/℃。且該體系與Ag電極共燒時(shí)不發(fā)生任何化學(xué)反應(yīng),表明其可用作低溫共燒陶瓷技術(shù)(LTCC)。
[Abstract]:In this paper, microwave dielectric ceramics with Li3Mg2NbO6 and Li2TiO3 as the representative of rock salt structure were systematically studied by the traditional solid state synthesis method. The experimental results show that the phase composition and doping have great influence on the microwave dielectric properties of the ceramics. The doping modification of Li3Mg2NbO6 microwave dielectric ceramics by Zn2 was studied in this paper. The optimum formula was determined by changing the doping amount of Zn2. Because the radius of doped ion Zn2 is slightly larger than that of Mg2, the lattice of Li3Mg2NbO6 ceramics is distorted, thus the Q 脳 f value is greatly increased, and the sintering temperature of the system is also slightly reduced. When the doping amount of Zn2 is 8 mol / 1, the best microwave dielectric properties are obtained by sintering the ceramics at 1120 鈩，

本文編號(hào)：2145843