Crystal structure and microwave dielectric properties of CaTiO3–La[Ga(1−δ)Alδ]O3 ceramics system

• B-site Ga3+ in CTLG substituted 50% by Al3+ exhibited excellent microwave dielectric properties.
• The crystal structure of CTLGA changes from orthorhombic to tetragonal when δ > 0.5.
• Intermediate phases disappear when the calcining temperature is higher than 1350 °C.
• All CTLGA samples show good performance when x = 0.62, 0.63, 0.64, 0.65, 0.66.

The crystal structure and microwave dielectric properties of 0.64CaTiO3–0.36La[Ga(1−δ)Alδ]O3 specimens have been investigated in this work. When δ ≤ 0.5, the crystal structure of 0.64CaTiO3–0.36La[Ga(1−δ)Alδ]O3 was orthorhombic, while it transformed into the tetragonal structure when δ > 0.5. When δ = 0.5, specimens exhibited good microwave dielectric properties with ϵr = 45.54, Q × f = GHz) and τf = −1.7 ppm/°C. The 50 at% substitution of Ga3+ by Al3+ in 0.64CaTiO3–0.36LaGaO3 benefited the Q × f value, the results showed that all samples of xCaTiO3–(1 − x)La[Ga0.5Al0.5]O3 (x = 0.62, 0.63, 0.64, 0.65, 0.66) exhibited ρr ≥ 96.8%, Q × f ≥ 39,000 GHz, 44 ≤ ϵr ≤ 48 and −8 ppm/°C ≤ τf ≤ +6 ppm/°C.

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