The structure, valence state, and dielectric properties of (Ba1−xSmx)(Ti0.99Mn0.01)O3 (BSTM) (x = 0.02‒0.07) ceramics prepared via a high temperature (1400 °C/12 h) solid state reaction were investigated. A homogeneous and dense microstructure was observed in all samples. With increasing Sm content, the crystal structure changed from tetragonal (x ≤ 0.06) to cubic (x = 0.07) and unit cell volume (V0) decreased continuously, which was mainly due to the substitution of Ba2+ ions by smaller Sm3+ ions in the perovskite lattice. Electron paramagnetic resonance investigation revealed that Mn ions were reduced from high valence to low valence under the role of Sm3+ donor, and only Mn2+ ions were observed at x = 0.07. The Curie temperature (Tc) moved to lower values, from 105.5 down to 20.4 °C, and the x = 0.07 sample satisfied Y5V specification with high permittivity (ε′RT > 13,000) and low loss (tan δ < 0.03).
The 8mm thick T1 state copper plate was cold rolled into 3mm, 2mm and 1mm thin plate sections, and its microstructure and texture were analyzed by optical metallographic microscope and X-ray diffraction (XRD). The mechanical properties were tested by cupping machine and micro-hardness tester. The results show that with the increase of cold rolling deformation, the grain size decreases and a strong (220) diffraction surface texture appears. The highest tensile strength is 421.76MPa, and the microhardness is 129.9HV, all of which are greatly improved, but the elongation decreases from 40% to 5%, and the fracture morphology changes from ductile fracture to quasi cleavage fracture.
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