Average and Local Structural Origins of the Optical Properties of the Nitride Phosphor La_3–xCe_xSi₆N₁₁ (0 < x ≤ 3)

Abstract

Structural intricacies of the orange-red nitride phosphor system La(3-x)Ce(x)Si6N11 (0 < x ≤ 3) have been elucidated using a combination of state-of-the art tools, in order to understand the origins of the exceptional optical properties of this important solid-state lighting material. In addition, the optical properties of the end-member (x = 3) compound, Ce3Si6N11, are described for the first time. A combination of synchrotron powder X-ray diffraction and neutron scattering is employed to establish site preferences and the rigid nature of the structure, which is characterized by a high Debye temperature. The high Debye temperature is also corroborated from ab initio electronic structure calculations. Solid-state (29)Si nuclear magnetic resonance, including paramagnetic shifts of (29)Si spectra, are employed in conjunction with low-temperature electron spin resonance studies to probes of the local environments of Ce ions. Detailed wavelength-, time-, and temperature-dependent luminescence properties of the solid solution are presented. Temperature-dependent quantum yield measurements demonstrate the remarkable thermal robustness of luminescence of La2.82Ce0.18Si6N11, which shows little sign of thermal quenching, even at temperatures as high as 500 K. This robustness is attributed to the highly rigid lattice. Luminescence decay measurements indicate very short decay times (close to 40 ns). The fast decay is suggested to prevent strong self-quenching of luminescence, allowing even the end-member compound Ce3Si6N11 to display bright luminescence.

Li4SrCa(SiO4)2:Ce3+, a highly efficient near-UV and blue emitting orthosilicate phosphor

“…Stokes shift is as small as possible [22]. In recent years, researches also confirmed that a rigid structure of host is responsible for a high quantum efficiency and good thermal stability [23][24][25][26][27][28].…”

First-principles study ofCe3+-dopedlanthanum silicate nitride phosphors: Neutral excitation, Stokes shift, and luminescent center identification

“…This experimental observation has been recently confirmed by Seshadri's group. 16 According to these facts, some preliminary discussions based on crystal structure and dielectric properties have been given to understand the difference between LaSi 3 N 5 :Ce and La 3 Si 6 N 11 :Ce. 16?…”

Average and Local Structure, Debye Temperature, and Structural Rigidity in Some Oxide Compounds Related to Phosphor Hosts

“…12 Θ D measured experimentally using these two methods for a number of phosphor hosts has been shown to agree well with values calculated from DFT-derived parameters. [12][13][14][15] In this work, we explore the structural signatures of several known oxide phosphor hosts, through a careful examination of the average and local structure determined using time-of-flight neutron scattering (including total scattering) and synchrotron powder diffraction methods. The oxide hosts Ba 2 SiO 4 , BaAl 2 O 2 , SrAl 2 O 4 , and Y 2 SiO 5 were studied using these scattering techniques and low-temperature heat capacity measurements.…”