Conversion of thermal energy to light energy and energy transfer in KGdF4: Eu3+,Tb3+ phosphors

Synthesis and optical properties of Gd4Al2O9:Eu3+, a red emitting phosphor with a strong negative thermal quenching effect

“…The mechanism of NTQ effect has been discussed in a number of other reports. 30–32 That is, with the increasing of temperature, the electrons obtain energy compensation from the electron traps formed from the matrix defects and then they transfer the energy to Eu 3+ to formation the effect, 33–36 which is described with Fig. 5(e).…”

“…In this paper, electron traps formed from the substitution of Eu 3+ for Gd 3+ lattice sites that are in two different coordination sites. 33–36 The mechanism is shown in Fig. 5(c), where the number of excited electrons in Eu 3+ through nonradiative relaxation to the ground state increases with increasing temperature, while electron traps are released from the defects into the 5 L 6 energy level of Eu 3+ upon heating, leading to an increase in the number of electrons in the radiative transition and thus enhanced emission of Eu 3+ .…”