Bochenek Dariusz, Bartkowska Joanna A, Kozielski Lucjan, Szafraniak-Wiza Izabela
Faculty of Science and Technology, Institute of Materials Engineering, University of Silesia in Katowice, 75 Pułku Piechoty 1a, 41-500 Chorzów, Poland.
Institute of Materials Science and Engineering, Poznan University of Technology, Jana Pawła II 24, 61-138 Poznan, Poland.
Materials (Basel). 2021 Apr 27;14(9):2254. doi: 10.3390/ma14092254.
This paper investigates the impact of the technological process (Mechanochemical Activation (MA) of the powder in combination with the Spark Plasma Sintering (SPS) method) on the final properties of lead-free Ba(FeNb)O (BFN) ceramic materials. The BFN powders were obtained for different MA duration times (x from 10 to 100 h). The mechanically activated BFN powders were used in the technological process of the BFN ceramics by the SPS method. The measurements of the BFNMA ceramic samples included the following analysis: Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS), DC electrical conductivity, and dielectric properties. X-ray diffractions (XRD) tests showed the appearance of the perovskite phase of BFN powders after 10 h of milling time. The longer milling time (up 20 h) causes the amount of the perovskite phase to gradually increase, and the diffraction peaks are more clearly visible. Short high energy milling times favor a large heterogeneity of the grain shape and size. Increasing the MA milling time to 40 h significantly improves the microstructure of BFN ceramics sintered in the SPS technology. The microstructure becomes fine-grained with clearly visible grain boundaries and higher grain size uniformity. Temperature measurements of the BFN ceramics show a number of interesting dielectric properties, i.e., high values of electric permittivity, relaxation properties with a diffusion phase transition, as well as negative values of dielectric properties occurring at high temperatures. The high electric permittivity values predestines the BFNMA materials for energy storage applications e.g., high energy density batteries, while the negative values of dielectric properties can be used for shield elements against the electromagnetic radiation.
本文研究了工艺过程（粉末的机械化学活化（MA）与放电等离子烧结（SPS）方法相结合）对无铅Ba(FeNb)O（BFN）陶瓷材料最终性能的影响。在不同的MA持续时间（x从10到100小时）下制备了BFN粉末。通过SPS方法将机械活化的BFN粉末用于BFN陶瓷的工艺过程。对BFNMA陶瓷样品的测量包括以下分析：扫描电子显微镜（SEM）、能量色散光谱（EDS）、直流电导率和介电性能。X射线衍射（XRD）测试表明，研磨10小时后BFN粉末出现钙钛矿相。较长的研磨时间（长达20小时）会使钙钛矿相的量逐渐增加，衍射峰更清晰可见。较短的高能研磨时间有利于晶粒形状和尺寸的较大不均匀性。将MA研磨时间增加到40小时可显著改善采用SPS技术烧结的BFN陶瓷的微观结构。微观结构变得细晶粒，晶界清晰可见，晶粒尺寸均匀性更高。BFN陶瓷的温度测量显示出许多有趣的介电性能，即高介电常数、具有扩散相变的弛豫性能以及高温下出现的负介电性能值。高介电常数使得BFNMA材料适用于储能应用，例如高能量密度电池，而负介电性能值可用于制造抗电磁辐射的屏蔽元件。
