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The current study investigated the dielectric and electrical properties of BaAl (2−2 x) (Zn 0.5 Ti 0.5) 2 x O 4 ceramics, with x = 0, 0.4%, 0.8%, 1.2% and 1.6%, via impedance spectroscopy. The co-doping of Zn and Ti improved the temperature stability over −100 °C–700 °C of ε r and lowered tan δ due to the electron-pinned defect-dipoles. Effects of oxygen partial pressure on the electrical, dielectric and ferroelectric properties of x = 1.6% ceramic were studied as well. The bulk conductivity of the N 2 –H 2 -sintered and O 2 -sintered samples was attributed to the e ' and h • , respectively. [ABSTRACT FROM AUTHOR]

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]

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]

Ba 2 Zn (1+ x ) Si 2 O (7+ x ) ceramics were prepared using the conventional solid-state method at 1200 °C for 3 h in air. Apart from the previously reported Ba 2 Zn (1+ x ) Si 2 O (7+ x ) ( x = 0) with a monoclinic structure ( C 2/c ), the end-member compositions at x = −1 and 1 exhibit single-phase β -BaSiO 3 with an orthorhombic structure ( P 2 1 2 1 2 1 ) and BaZnSiO 4 with a hexagonal structure ( P 6 3 ), and possess a coexistence of weak ferroelectricity and low-permittivity microwave dielectric properties. A reduction in Zn 2+ content mainly decreases the intensity of the ε r anomaly peak at lower temperature and increases the ε r (or frequency) stability against temperature. The Zn 2+ -rich BaZnSiO 4 phase has a τ f value of −181 ppm/°C, whereas the τ f value of Zn 2+ -free BaSiO 3 phase decreases to −35.4 ppm/°C. The Zn 2+ deficiency in Ba 2 ZnSi 2 O 7 composition could inhibit the presence of BaZnSiO 4 phase and improve the τ f value, whereas excessive Zn 2+ cations prompt the formation of the BaZnSiO 4 phase to deteriorate significantly the τ f value. [ABSTRACT FROM AUTHOR]