Influence of thermal treatment on structural, morphological and optical characteristics of upconvertors

Abstract

The upconverting phosphors are materials of great interest for optoelectronics operating in the near infrared region. The preparation of highly spherical Y2O3:Yb,Er particles are synthesized via spray pyrolysis from common nitrate solution with fixed dopants ratio of Yb/Er=10. The processing conditions are as follows: precursor concentration 0.1M, atomization frequency 1.3 MHz, temperature regime 200-900-900°C and air flow rate 1,6 dm3/min. The as-prepared particles collected in the electrostatic precipitator are additionally thermally treated at 1100 °C for 12, 24 and 48 hours. Detailed structural analyses are performed by X-ray powder diffraction (XRPD) based on which the structural refinement is done using Topas Academic Software. The results imply that with the increase of calcination time crystallite size increasing along with microstrain diminishing. The particle morphological characteristics are studied by scanning electron microscopy (SEM) and are further correlated with specific surface area (BET), size distribution (LPS) and optical properties followed through photoluminescence measurements (PL).