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Lead-free (Ba 0.85 Ca 0.15 )(Ti 0.9 Zr 0.1 )O 3 -xwt%CuOywt%Y 2 O 3 (BCZT-Cu x Y y ) ceramics with high piezoelectricity were synthesized by the conventional solid-state reaction method. The role of Cu and Y (Cu/Y) in sintering, phase transition, and electrical properties of such ceramics was systematically studied. The results indicated that the sintering temperatures of BCZT-Cu x Y y decreased by at least 100 °C due to the low melting point of CuO. The promotion effect of Cu/Y on phase transition lied in the improvement of T C by 5–15 °C and the coexistence of O+T phase near room temperature. The contribution of Cu/Y to electrical properties was mainly ascribed to the grains growth, the formed oxygen vacancies and lattice distortions, and the donor doping effect of Y 3+ . Adding 0.10 wt% Cu 2+ and 0.06 wt% Y 3+ into BCZT dramatically improved the electrical properties as following: d 33 = 552 pC/N, ε m = 10175, ε r = 4546, tanδ = 0.016, T C = 100 °C, k p = 0.475, Q m = 157.2, P r = 10.82 μC/cm 2 and E C = 2.33 kV/cm. A plausible mechanism was obtained to explain the reaction process and the favorable performances of BCZT-Cu x Y y . Co-doping Cu 2+ and Y 3+ into BCZT could be a promising method to improve and balance the sintering, phase transition, and electrical properties for potential practical applications of lead-free piezoceramics. [ABSTRACT FROM AUTHOR]

Quartz and clay are substituted gradually by fly ash using a triaxial ceramic formulation under simulated industrial conditions and the effects of fly ash substitution on the macroscopic properties and microstructures of the sintered ceramics are evaluated systematically. With the substitution of 35 wt% (1250 °C), the ceramic sample exhibited optimal properties, including linear shrinkage of 15.61%, bulk density of 2.39 g cm-3, water absorption of 0.62% and flexural strength of 41.70 MPa, due to the accelerated densification and fly ash-spurred needle-shaped mullite. The microstructure analysis shows that the sintered matrix consists of three types of particles, quartz-, clay- and feldspar-like particles showing sintering behavior with respect to filling the glassy matrix with preserved morphology, precipitating mullite crystals, and fusing with the surrounding glassy matrix, respectively. The strength of the fly ash - containing ceramics is analyzed by the dispersion-strengthening mechanism and porosity and the results indicate that the fly ash particles affect the mechanical strength due to Griffith flaws when the total porosity is less than 25% and pores at higher total porosity. This study provides a viable strategy to recycle industrial fly ash in the production of architectural ceramics. [Display omitted] • Quartz and clay are substituted by fly ash in a triaxial ceramic formulation. • The ceramic preparation is under simulated industrial conditions. • The substitution effects on macro-properties and microstructures are evaluated. • Three types of particles exist acting as quartz, clay, and feldspar, respectively. • The strength is analyzed by the dispersion strengthening mechanism and porosity. [ABSTRACT FROM AUTHOR]