Effect of Mn impurity on the dielectric loss of PMW-PT-PNN ceramics

摘要: Where C is the capacitance, e dielectric constant of dielectrics, V and t are volume capacitor active body thickness dielectrics respectively. To achieve greater efficiency, reducing much more effective than increasing alone. Therefore, great efforts have been made to produce a thinner ceramic layer. Unfortunately, serious problems may occur because dc ac fields applied layer become stronger with layers. The increase field results in decrease constant, while an loss [2]. For barium titanate ceramics, these two serious, especially stability for loss. As indicated Fig. 1, dissipation factor MLCC (commercially available one titanate-based dielectrics) shows strong dependence at room temperature, exceeding specification 2.5% Electronic Industries Association (EIA) X7R designation (<±15% change capacitance between −55 ◦C 125 ◦C) when drive level above 2 kV/cm. Thus, applications, studying mechanism materials, minimize its effect, significance. It widely accepted that small amounts manganese usually incorporated BaTiO3 as controller [3, 4]. But role Mn has not fully understood yet. Also, doping needed further investigation relaxor which characterized by higher permittivity lower sintering temperature important compositions MLCC. Moreover, it well known causes evident aging behavior [5, 6], but clarified. this letter, we examined PMW-PT-PNN ceramics discuss influence various levels on characteristics. A composition 0.27Pb(Mg1/2W1/2)O3-0.33PbTiO3-0.40Pb(Ni1/3Nb2/3)O3 was used throughout study. samples were prepared two-stage calcination method. Prior reaction PbO TiO2, Columbite NiNb2O6 (NN) wolframite MgWO4 (MW) synthesized calcining analytical reagent (AR) grade Ni(CH3COO)2 Nb2O5 1000 6 h MgCO3Mg(OH)2 · 6H2O WO3 also h. These phases then batched Pb3O4, excess MnO2 form several modified 0.05, 0.1, 0.2, 0.3 mol% MnO2. Excess added obtain core-shell structure [7]. condition batches 800 calcined powders ball-milled again, ensuring fine particle size before sintering. Then dried pressed disks (10 mm diameter 1 thick) under application 100 MPa pressure. pellets buried same fired covered alumina crucible 1100 different heating rates. Finally, silver-coated specimens heat-treated 600 ◦C. properties sintered disk studied function using automatic measurement system incorporating Environmental Chamber (Delta 2300) LCR precision meter (HP 4284A). kept 25 ◦C, time varied range 1–100