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Mn O 2 -modified Pb 0. 9 6 2 5 Sm 0. 0 2 5 ( Mg 1 / 3 Nb 2 / 3) 0. 7 1 Ti 0. 2 9 O 3 ceramics were prepared via a solid-state reaction approach. Results of detailed characterizations revealed that the addition of Mn O 2 has influence on the grain size, and all samples exhibit a pure perovskite structure. As the content of manganese increases, the volume of tetragonal phase increases. The ceramics with 1.5 mol.% Mn O 2 show a high electro-strain of 0.151% at 2 kV/mm. Therefore, this study provides a new insight into the role of Mn O 2 addition in tailoring the electrical properties of the Sm-PMN-PT ceramics by acceptor doping. [ABSTRACT FROM AUTHOR]

The present study deals with a microwave-assisted oxidation roasting oxide–sulphide zinc ore technology of with addition of manganese dioxide. Effects of roasting parameters such as MnO2 addition level, roasting temperature, and holding time are studied by using the Central Composite Design (CCD). Meanwhile, zinc calcines are characterized by phase compositions analyses(XRD), structure characteristics of minerals (FT-IR), micro-area chemical analyses (SEM-EDAX) and elemental valence bonding analyses (XPS), which prove to be in accordance with the CCD results. The optimum roasting conditions are decided as MnO2 addition level being 85.14 %, roasting temperature 680 °C, and holding time 41 mins, and oxidation degree of zinc can reach 88.22 %. Besides, when MnO2 addition level reaches a certain value, zinc will aggregate in a form of ZnMn2O4, one battery material.

Lithium tantalite (LiTaO3) is an excellent single crystal, only a few studies focused on polycrystalline LiTaO3 ceramics, because it is difficult to sintering densification in fabrication process by common sintering. In this paper, LiTaO3 composite ceramics with added 3 wt% MnO2 were obtained by hot-pressing sintering at different temperatures from 1200 to 1350 °C. The sinterability, microstructure and dielectric properties of LiTaO3 ceramics fabricated at sintering temperatures were investigated. The relative density of the LiTaO3 ceramics was significantly enhanced as the sintering temperature increases first and then decreased. The LiTaO3 ceramics achieved the highest relative density (98.6%) and shown homogeneous microstructure when sintered at 1300 °C. The LiTaO3 and manganese oxide phases were observed in the MnO2/LiTaO3 ceramics fabricated at different sintering temperatures. The dielectric properties of MnO2/LiTaO3 ceramics were significantly influenced by the sintering temperatures. The study of dielectric properties revealed that the specimen had excellent dielectric properties when sintering temperature was 1300 °C and the dielectric constant was 78, as it tends to stay invariable at room temperature. [ABSTRACT FROM AUTHOR]

In our previous work, we developed lead-free potassium sodium niobate-based textured ceramics with a piezoelectric response (d33*) of 505 pm/V and superior thermal stabilities. However, the dielectric loss of the ceramics is 3.5% at 1 kHz which is higher than the PZT-based ceramics. To solve this problem, MnO2 was introduced into the KNLN-BZ-BNT ceramics in this work. It is found that the introduction of MnO2 does not affect the crystalline phase nor grain size. In addition, the effect of MnO2 of less than 2.0% on the texture degree is insignificant. The 0.5% and 1.0% MnO2 modified samples show similar electrical properties and thermal stability as the one without MnO2. The addition of MnO2 can reduce the dielectric loss. Compared to the ceramic with 0.5% MnO2 addition, the 1.0% MnO2-added KNLN-BZ-BNT ceramic possesses a better performance. [ABSTRACT FROM AUTHOR]