Synthesis and Unique Photoluminescence Properties of Eu₂Ti₂O₇ and Eu₂TiO₅

Abstract

The europium titania materials, pyrochlore Eu2Ti2O7 and orthorhombic Eu2TiO5, were synthesized from a mixture of Eu2O3 and TiO2 using the solid‐state reaction method. The structural and optical properties of these titania materials were investigated using X‐ray diffraction analysis, photoluminescence (PL) analysis, PL excitation (PLE) spectroscopy, and diffuse reflectance spectroscopy. Temperature dependence of the PL intensity was measured between T = 20 and 450 K and analyzed on the basis of various theoretical models. A remarkable increase in the PL intensity with increasing T was observed in these titania materials at higher temperatures, above ~140 K, and well explained by a trap/reservoir model. Interestingly, a dramatic decrease in the electric‐dipole emission component relative to the magnetic‐dipole one was observed in Eu2Ti2O7 above T ~ 140 K. The schematic energy‐level diagram for Eu3+ in the Eu2Ti2O7 host was proposed for the sake of a better understanding of the PL and PLE processes in this type of phosphorescent material.

Vertical Strain-Driven Antiferromagnetic to Ferromagnetic Phase Transition in EuTiO3 Nanocomposite Thin Films

“…To exclude the possible existence of Eu-rich phases such as Eu 2 Ti 2 O 7 , Eu 2 TiO 5 , Eu 2 TiO 4 , and Eu 3 Ti 2 O 7 , , which could possibly form, we investigated several different regions of the VAN films by high-resolution STEM. Figure S1 shows an example of the HR-STEM image along with a fast Fourier transform (FFT) pattern obtained from the selected area for the x = 0.2 film near an ETO/EO boundary.…”

Narrow-band dazzling red-emitting (LiCaLa(MoO4)3:Eu3+) phosphor with scheelite structure for hybrid white LEDs and LiCaLa(MoO4)3:Sm3+,Eu3+-based deep-red LEDs for plant growth applications

“…A change in the PL spectra was observed after calcination at T c = 1000 °C and 1100 °C in the case of Eu 2 TiO 5 and c-Eu 2 O 3 , while the complete disappearance of the peaks at 1200 °C suggested the complete formation of Eu 2 Ti 2 O 7 . 23 The stoichiometric phosphor Al 2 O 3 –Eu 2 O 3 was reported, where its PL emission showed the development of distinct Eu 3+ emissions with peaks at 620 nm and 700 nm. It shows the highest intensity at Eu 2 O 3 ( x = 1).…”

“…Another reason may be that due to the parity-forbidden 4f → 4f transition, activation of vibronic quanta will further increase the luminescence intensity. 23 Fig. 6(b) depicts the PL emission of the LiCaEu 1.0 (MoO 4 ) 3 red phosphor recorded at increasing temperatures in the range of 25 °C to 225 °C upon excitation at 395 nm.…”

Phase transition of Eu2Ti2O7 under high pressure and a new ferroelectric phase with perovskite‐like layered structure

“…20 The optical properties, magnetic properties, and grain growth behavior of pyrochlore Eu 2 Ti 2 O 7 have been studied, systematically. [21][22][23] However, the ferroelectricity of PL Eu 2 Ti 2 O 7 has not been confirmed yet. The structure transition of Eu 2 Ti 2 O 7 from pyrochlore-PL was firstly reported in 1991, using a 2-step high-pressure treatment.…”