Manipulation of upconversion property and enhancement of sensitivity by tailoring the local structure

Tailoring the local crystal environment around the activators is one of an important way to enhance the upconversion (UC) luminescence intensity. Herein, we substitute the Y 3+ lattice with La 3+ ion gradually in Y 2 Ti 2 O 7 :Yb 3+ , Er 3+ phosphor and investigate the effect of La 3+ concentration on the UC luminescent properties as well as the temperature sensing behaviors. During the phase transformation process from cubic Y 2 Ti 2 O 7 to monoclinic La 2 Ti 2 O 7 , the La 3+ ions also play an important role on the adjustment of size and morphology of particles. Furthermore, the cooperation of La 3+ ion is in favor of the crystal growth toward the easy growth directions. The UC luminescence intensities can be enhanced efficiently with the increasing of La 3+ concentration. The sensitivity for temperature sensing can be improved by the increasing of La 3+ concentration in the Y 2 Ti 2 O 7 and La 2 Ti 2 O 7 two‐phase coexistence system and the maximum S A is 45.3 × 10 −4  K −1 at 410K when the La 3+ concentration is 80%. The maximum S A and corresponding temperature can be adjusted by controlling the La 3+ concentration, which means that (Y 0.94‐x La x ) 2 Ti 2 O 7 : Er 3+ /Yb 3+ phosphors may be applicable to different working environment.