MnO2 as an effective sintering aid for difficult-to-sinter LiTaO3 -based ceramics: Densification and dielectric properties
MnO2 as an effective sintering aid for difficult-to-sinter LiTaO3 -based ceramics: Densification and dielectric properties
复制标题
MnO2 作为难烧结 LiTaO3 基陶瓷的有效烧结助剂：致密化和介电性能
DOI：
10.1016/j.jallcom.2020.154546
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发表时间：
2020
影响因子：
6.2
通讯作者：
Wang John
中科院分区：
文献类型：
--
作者：
Zhang Youfeng;Yao Yali;Ren Jiangwei;Kong Haijuan;Wang Bo;Wang Zhongyang;Zhang Zhixiao;Wang John
致密多晶LiTaO_3(LTO)陶瓷因其烧结性差而鲜有报道，尽管LTO单晶是著名的压电性和铁电性材料之一。本研究分别在1200℃、1250℃、1300℃和1350℃的无压烧结条件下制备了MnO2含量分别为3wt%和5wt%的LiTaO_3基陶瓷(简称3MLT和5MLT)，研究了烧结温度对其烧结性、微观结构演变和介电性能的影响。随着烧结温度的升高，LiTaO_3基陶瓷的烧结密度先显著增加，然后降低。在1250℃烧成的3MLT和5MLT的烧结密度分别为92.6%和93.1%，且两种成分都表现出比较均匀和良好的晶化组织。适量的MnO_2进入LiTaO_3晶格形成固溶体，当加入过量的MnO_2时，在晶界和结合处形成Mn3O_4，固溶度与烧结温度有关。研究了3MLT和5MLT陶瓷的介电性能与频率的关系，结果表明：3MLT和5MLT陶瓷的介电性能与烧结温度有很强的相关性，介电常数随烧结温度的升高先增大后减小。随着烧结温度的升高，介电损耗先减小后增大。3MLT和5MLT在1250℃和1350℃烧结时的介电常数均达到最大值。当烧结温度为1250℃时，介电损耗最小，为两组分的最佳烧结温度。
Dense polycrystalline LiTaO3(LTO) ceramics have rarely been reported due to their poor sinterability, although LTO single crystals are among the well-known piezoelectric and ferroelectric. In this study, LiTaO3-based ceramics with 3 wt% and 5 wt% MnO2(referred to 3MLT and 5MLT, respectively) are prepared by pressure-less sintering at different temperatures of 1200 °C, 1250 °C, 1300 °C and 1350 °C, respectively, and the effects of sintering temperature on the sinterability, microstructure development and dielectric properties are investigated. The sintered density of the LiTaO3-based ceramics increases significantly at first with increasing of sintering temperature, and then decreases afterwards. Sintered densities of ∼92.6% and 93.1% were achieved for 3MLT and 5MLT sintered at 1250 °C, respectively, and both compositions show a rather homogeneous and well-developed grained microstructure. A moderate amount of MnO2was entered into the LiTaO3lattice to form a solid solution, however, Mn3O4was formed at the grain boundaries and junctions when excess amount of MnO2added, where the solid solubility is dependent on the sintering temperature. The dielectric properties of both 3MLT and 5MLT ceramics, studied as a function of frequency, show a strong dependence on sintering temperature, where the dielectric constant increases first and then decreases with the increasing of sintering temperature. The dielectric loss first decreases and then increases with the increasing of sintering temperature. Both 3MLT and 5MLT demonstrate a maximum in dielectric constant when sintered at 1250 °C and 1350 °C, respectively. The lowest dielectric loss could be obtained at 1250 °C, which was selected as the optimum sintering temperature for both compositions.