Quantitative analyses of electric field–induced phase transition in (Na, K)_0.5Bi_0.5TiO₃:Eu ceramics by photoluminescence

Abstract

Most reported results about phase transition probed by the photoluminescence (PL) spectra of Eu 3+ ions are qualitative, but the quantitative analyses of phase transition were presented in this work. We fabricated (Na 0.8 , K 0.2 ) 0.5 Bi 0.497 Eu 0.003 TiO 3 (NKBT20:Eu) ferroelectric ceramics and investigated the phase structures and the PL spectra of NKBT20:Eu ceramics before and after poling at different electric fields.The PL spectra indicate a phase transition from tetragonal phase (T phase) to rhombohedral phase (R phase) within NKBT20:Eu ceramics after poling, consistent with the analyses by X-ray diffraction (XRD). Moreover, the emission intensity ratios of the "hypersensitive" transition 5 D 0 → 7 F 2 to the magnetic dipole transition 5 D 0 → 7 F 1 could be used to calculate the fractions of the phase transition quantitatively, which were further confirmed by XRD Rietveld refinements. This study provides a different perspective to investigate the phase transition induced by electric field for NKBT20:Eu ceramics, qualitatively and quantitatively, and the method is expected to be useful in more cases of phase analyses.

Analyses of Electric Field-Induced Phase Transformation by Luminescence Study in Eu3+-doped (Na, K)0.5Bi0.5TiO3 Ceramics

“…Thus, the intensities of MD and hypersensitive transitions indicate the environments of Eu 3+ ions. Unpoled NKBET20 ceramics present a phase structure with R phase and T phase coexisting, while electric fields could induce a phase transformation, which are also reflected on the luminescence spectra [27]. As shown in Figure 1, with electric fields increasing, the intensities of the transition 5…”

“…The luminescence lifetimes of Eu 3+ ions in NKBET10 and NKBET30 ceramics are found be to 685.3 µs and 754.1 µs, respectively. In our earlier work [27], we show that using the luminescence spectra of NKBET10 and NKBET30 ceramics as references, the variations of luminescence spectra could be further utilized to quantitatively calculate the phase transformations in NKBET20 ceramics. Similar to the luminescence spectra, information about phase transformations could be extracted from luminescence decay curves.…”

“…We present that the decay curve method could be used to analyze the phase transformation induced by electric fields in this work, yet it can be used in other occasions of phase transformations. Adapted from our earlier work [27].…”

“…(A) 0 kV/cm, (B) 10 kV/cm, (C) 20 kV/cm, (D) 30 kV/cm, (E) 40 kV/cm, (F) 50 kV/cm. Adapted from our earlier work[27].…”

Crystallization Mechanism and Optical Properties of Antimony-Germanate-Silicate Glass-Ceramic Doped with Europium Ions

“…Similar to excitation spectra, there are also hypersensitive and independent of environment transitions. Selected information about that phenomena are in Table 3 [ 12 , 14 , 39 , 40 , 41 ].…”