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The structure and dielectric properties of BaAl (2−2 x) (Zn 0.5 Ti 0.5) 2 x O 4 ceramics were investigated. Single-phase solid solutions in space group P6 3 (No. 173) were confirmed when 0% ≤ x ≤ 1.6%. [Zn 0.5 /Ti 0.5 ]3+ averagely occupied four symmetrically inequivalent Al sites, and Al1/(Zn,Ti)–O, Al2/(Zn,Ti)–O and Al3/(Zn,Ti)–O bond lengths increased with increased x. Two dielectric anomalous peaks existed, the first peak referred to second-order ferroelectric transition. Stability was significantly improved by moving the first dielectric abnormal peak from 123 °C to −22 °C due to the lower atomic shift amplitude Δz of B cations along the polar axis. The co-doping of Zn2+ and Ti4+ played a decisive role in realizing an ultrabroad temperature range (−100 °C–700 °C) of stability (−27 ppm/°C ≤ TCC ≤ +10 ppm/°C), which met the conditions of C0G or NP0 multilayer ceramic capacitors (±30 ppm/°C). Superior insulating properties were performed by high resistivity of > 1014 Ω cm. [ABSTRACT FROM AUTHOR]

This study systematically investigated the structural, dielectric, and ferroelectric properties of BaAl(2−2x)(Mg0.5Ti0.5)2xO4 ceramics in the 0 ≤ x ≤ 0.04 range. Single‐phase solid solutions in the P63 space group with hexagonal crystal symmetry were confirmed in the composition range of 0 ≤ x ≤ 0.03. The bond lengths of Al1/(Mg,Ti)–O, Al2/(Mg,Ti)–O, and Al3/(Mg,Ti)–O increased with the increase in x, as confirmed through the Rietveld refinement and evolutions of corresponding modes in Raman spectra. The temperature stability of dielectric properties improved at a composition around x = 0.03, and the dielectric constant εr ascended with the increase in x. Ultrabroad temperature stability (−100°C to 700°C) was obtained, and an optimal combination (εr = 18.5, tan δ < 10−3, −22 ppm/°C ≤ TCC ≤ +20 ppm/°C, resistivity ~4.5 × 1014 Ω·cm) was achieved for the x = 0.03 ceramic sintered at 1260°C in air for 6 hours. The increase in stability was ascribed to the variations in axial bonds, and lattice distortions were determined through high‐resolution transmission electron microscopy. The x = 0.03 ceramic could be a promising candidate for C0G or NP0 multilayer ceramic capacitors because of its low loss, high reliability, superior insulating properties and comparatively low‐cost raw materials. [ABSTRACT FROM AUTHOR]

Ba 2 ZnSi 2 O 7 ceramic was prepared by conventional solid-state method and sintering under four different atmospheres (air, O 2 , N 2 , and N 2 –1 vol% H 2). The Ba 2 ZnSi 2 O 7 ceramic exhibited a single phase under air, O 2 , and, N 2 , whereas two phases (including BaSiO 3 impurity) were observed under the N 2 –1 vol% H 2 atmosphere due to Zn2+ evaporation. Dielectric loss was proportional to oxygen partial pressure due to the conduction mechanism of dominant holes. The Ba 2 ZnSi 2 O 7 ceramic exhibited good microwave dielectric properties (ε r = 8.3, Q × f = 27200 GHz, τ f = −41.5 ppm/°C) under the N 2 –1 vol% H 2 atmosphere, making it a novel candidate with good anti-reductive characteristics for base metal electrode–multilayer ceramic capacitor applications. [ABSTRACT FROM AUTHOR]