Low dielectric loss and enhanced tunable properties of Mn-doped BST/MgO composites

• Published in: Journal of alloys and compounds Vol. 490; no. 1; pp. 353 - 357
• Main Authors: Cui, Jiandong, Dong, Guixia, Yang, Zhimin, Du, Jun
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 04.02.2010; Elsevier
• Subjects: BST composites; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dielectric loss; Dielectric loss and relaxation; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Mn-doped; Physics; Tunability; Dielectric loss; Tunability; Mn-doped; BST composites; Impurity density; Microwave radiation; Magnesium oxide; Doping; Manganese additions; Dispersive spectrometry; Composite materials; Sintering; Dielectric losses; Solid state reaction; Impurity site; Non linear effect; Barium Strontium Titanates Mixed
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2009.09.185

Ba 0.6Sr 0.4Ti 1− x Mn x O 3 [BST(Mn), x = 0.0000, 0.0025, 0.0050, 0.0075, 0.0100 and 0.0125] powders were synthesized by solid-state reaction process, and then BST(Mn)/MgO ceramic composites (60 wt% MgO) were fabricated by conventional ceramic process. Mn was found distributed in the BST grains homogeneously after sintering at 1420 °C for 4 h, neither grain-boundary segregation nor diffusion into the MgO grains could be found obviously. The dielectric nonlinearity of the materials was enhanced with the addition of Mn-dopant, and relatively high tunability, more than 27% (8 kV/mm DC field, 500 Hz), was obtained in BST(Mn)/MgO samples with x ≤ 0.0100. The dielectric loss at microwave frequency of the samples with Mn-dopant was significantly reduced, and a tremendously low dielectric loss was acquired for the sample with x = 0.0050, which is only 4.5 × 10 −3 (at 3.64 GHz). Both the low dielectric loss and enhanced tunable properties of the BST(Mn)/MgO composites are useful for tunable microwave applications.