Large enhancement of upconversion luminescence in Er~(3+)/ ln~(3+):Ba_(0.85)Ca_(0.15)TiO_3 lead-free piezoelectric ceramics

摘要

A series of In_(3+)-doped Ba~(0.85)Ca~(0.15)TiO~(3):0.75%Er_(3+)/ x In_(3+)(BCT:Er/ x In) lead-free piezoelectric ceramics with excellent upconversion luminescence were synthesized by the solid state reaction method. The effects of In_(3+)content on the crystal structure, ferroelectric, dielectric, piezoelectric, and upconversion luminescence properties were systematically studied. Under 980 nm excitation, a giant enhancement of the green emission (550 nm) by 10 times is achieved upon 2.5% mol In_(3+)doping, which is rarely observed in rare-earth ions-doped perovskite ferroelectric materials. The ultraviolet-visible-near infrared absorption measurements show that the In_(3+)doping may improve the dissolution of Er_(3+)ions and modify the isolate-/clustered-Er_(3+)ratio for x  ≤ 2.5%, resulting in the enhancement of the absorption cross-section, thereby contributing to the enhancement of green luminescence. Unfortunately, the In_(3+)doping suppresses the ferroelectric and piezoelectric properties of the BCT:Er/ x In ceramics. This problem can be resolved by adding a small amount (1 mol%) of Yb_(3+)to the BCT:Er/ x In ceramics to restore their good ferroelectric and piezoelectric properties. Such In_(3+)and rare-earth ions co-doped ceramics with greatly enhanced upconversion luminescence and good ferroelectricity and piezoelectricity may have potential applications in electro-optical devices.