Preparation and luminescence properties of orange–red Ba3Y(PO4)3:Sm3+ phosphors

An efficient orange–red‐emitting LiNa3P2O7:Sm3+ pyrophosphate: Structural and optical analysis for solid‐state lighting

“…In the second region between 300 and 800 nm, seven absorption bands were observed at 346, 362, 374, 401, 416, 438 and 476 nm. These bands were attributed to the 6 H 5 /2→ 4 H 13 /2 , 6 H 5 /2→ 4 D 3/2 , 6 H 5 /2→ 6 P 7 /2 , 6 H 5 /2→ 4 F 7 /2 , 6 H 5 /2→ 6 P 5 /2 , 6 H 5 /2→ 4 G 9 /2 and 6 H 5 /2→ 4 I 11 /2 energy levels, respectively . Similar bands were also observed in the excitation spectra of phosphors (shown in a later section).…”

“…The emission spectra of LNPO:Sm 3 + phosphors were recorded using 401 nm excitation wavelengths and are presented in Figure . The spectra show three distinct emission peaks at 565, 600 and 645 nm corresponding to intra‐configurational 4 f– 4 f transitions of Sm 3 + ions from the excited state ( 4 G 5 /2 level) to ground states ( 6 H J , J = 5/2, 7/2 and 9/2, respectively) . The strongest peak at 600 nm is dominant over other peaks.…”

“…The spectrum shows a broad peak centered at 55.2 eV, which indicates the ionic state of Li atoms and the formation of a single bond with oxygen (Li–O) . Figure (c) shows the high‐resolution spectrum of O 1 s with four different peaks at binding energies of 530.8 eV (O1), 531.7 eV (O2), 532.9 eV (O3) and 535.9 eV (O4) . The first three peaks O1, O2 and O3, fitted to equal full‐width at half‐maxima (FWHM) of 1.72 eV, as shown in Table , are due to the oxygen atoms forming different bonds with the elements in the phosphor, such as P–O–P (or double bond P = O), P–O–Li and P–O–Na (or partially from Sm–O), respectively.…”

“…They have attracted attention due to the unique spectroscopic behavior of their polyhedral metal cations with well‐defined and low symmetry coordination, as well as dielectric and fluorescence properties . The role of RE ions in modern lighting and displays is appreciable due to the abundant emission colors based on their 4 f → 4 f or 5 d → 4 f transitions . Among the RE ions, Sm 3 + plays a vital role in luminescent materials, producing intense orange–red fluorescence due to the transition of ions from the 4 G 5 /2 excited state to the 6 H 5 /2 ground state, as well as to higher 6 H J levels ( J = 7/2, 9/2 and 11/2) under near‐ultraviolet (NUV) excitation, which matches well with the emission of InGaN chips.…”

Toward temperature‐dependent Bi3+‐related tunable emission in the YVO4:Bi3+ phosphor

“…In this case, we experimentally measured the diffuse reflectance spectra of the YVO 4 and YVO 4 :2.0%Bi 3+ samples by using a UV‐visible (235‐600 nm) spectrophotometer (Shimadzu UV‐2450, Shimadzu Corporation, Kyoto, Japan) of bulk YVO 4 and YVO 4 :2.0%Bi 3+ . On basis of the Kubelka‐Munk method (ie, K = (1 − R ) 2 /2 R , where K denotes the Kubelka‐Munk function based on the relationship of ( K*hʋ ) 1/2 = f ( h*ʋ ), h is the Planck constant, ʋ is the light frequency, and R is the reflectance [%]), two E g values that correspond to the bulk YVO 4 (ie, 3.26 eV) and YVO 4 :2.0%Bi 3+ (ie, 3.04 eV) can be achieved. Cleary, the experimentally achieved E g value of YVO 4 :2.0%Bi 3+ is smaller than that of bulk YVO 4 , which is well consistent with the E g variation trend that is reflected by the DFT.…”