| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1487348 | Materials Research Bulletin | 2015 | 6 Pages |
•The SCNTGx ceramics were prepared by solid-state reaction method.•The partial introduction of Ga2O3 could improve the Q × f value in SCNTGx.•The τf value could be predicted by the change of tolerance factor (t).•The ϵr ∼43.7, Q × f ∼60,100 GHz and τf ∼8.3 ppm/°C can be obtained at x = 0.5.
Structural features and microwave dielectric properties of (Sr0.2Ca0.488Nd0.208)Ti1−xGa4x/3O3 (SCNTGx, 0.2 ≤ x ≤ 0.6) samples were studied. The X-ray patterns revealed that a single phase with orthorhombic perovskite-like structure was obtained in the range of x = 0.2–0.4. A certain amount of Ga2O3 phase was detected at x = 0.5 from the XRD data. However, some unknown phase was formed as a secondary phase when x increased up to 0.6. Moreover, as Ga3+ concentration increased, the ϵr decreased due to the smaller ionic polarization of Ga3+ than that of Ti4+, the Q × f value increased firstly and then decreased because of the existence of the unknown secondary phase. And the τf values changed from a positive to negative value, arising from a reduction in tolerance factor (t) for tilted region (t < 1) in perovskite structure. Furthermore, an extra Raman band centered at about 240/236 cm−1 was detected in SCNTGx ceramics at x = 0.5, 0.6, which was caused by the appearance of the Ga2O3 phase. The SCNTGx (x = 0.5) ceramic sintered at 1350 °C for 4 h showed good microwave dielectric properties with ϵr = 43.7, Q × f = 60,100 GHz (at 4.71 GHz) and τf = 8.3 ppm/°C. Obviously, the introduction of Ga2O3 could efficiently improve Q × f value of the SCNTGx specimens.
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