Temperature-dependent photoluminescence and optical thermometry performance in Ca3Bi(PO4)3:Er3+ phosphors

Abstract

Single phase crystalline Er3+ doped Ca3Bi(PO4)3 (CBP:Er3+) phosphors were prepared using chemical co-precipitation route. The structural, optical, morphological and luminescent characteristics of the CBP:Er3+ phosphors for optical thermometry and optoelectronic applications were examined. The diffraction patterns of the samples were matched well with the standard data with single phase cubic structure and not changed after doping. The reflectance spectrum shows the various absorption peaks owing to Er3+ ions. The field emission scanning electron microscopy (FE-SEM) images disclose that the sample particles have asymmetric and spherical particles with some aggregation. Elemental analysis and mapping confirm the existence of various compositional elements. The PL spectra specifies that the phosphor can be effectively excited by near-ultraviolet (n-UV) LED, which was well-observed from n-UV excitation spectrum. As-prepared phosphor emits the visible emission at 523 (2H11/2 → 4I15/2), 552 (4S3/2 → 4I15/2) and 662 nm (4F9/2 → 4I15/2) under n-UV excitation (376 nm). The calculated color coordinates reveal the green color emission from the phosphor under 376 nm excitation with high color purity. PL variation and fluorescence intensity ratio from the thermally coupled 4S3/2 and 2H11/2 levels of Er3+ ions can be utilized to explore applications in optical thermometry and found the good temperature sensitivity in the range of 300–473 K. Hence, the mentioned structural and optical characteristics of the prepared CBP: xEr3+ phosphors will find fascinating applicability in optical thermometry, and other optoelectronic devices.