Effect of tetragonal to cubic phase transition on the upconversion luminescence properties of A/B site erbium-doped perovskite BaTiO₃

Abstract

At the critical temperature, B-site doping with erbium shows abnormal upconversion efficiency as a function of temperature in perovskite crystals, which was attributed to the symmetry of the crystalline structure around the erbium ions.

Nonlinear Optical Thermometry—A Novel Temperature Sensing Strategy via Second Harmonic Generation (SHG) and Upconversion Luminescence in BaTiO3:Ho3+,Yb3+ Perovskite

“…Such a significant change in the band intensity ratio I SHG /I UCL is due to the intrinsic phase transition of the randomly‐oriented (nonpolarized) perovskite crystals, [ 42 ] from the broken inversion symmetry to inversion symmetry, which is well confirmed for BaTiO 3 in different reports. [ 34,36,42,43,50–52 ] The relative change in the I SHG /I UCL ratio is associated with the SHG process, which is forbidden in the cubic phase of BaTiO 3 (centrosymmetric structure). However, the SHG signal does not completely disappear (see Figure 2b), even at the highest temperature measured.…”

“…[ 32,33 ] With increasing temperature, different regions of the material change their crystallographic orientations, altering the crystal structure symmetry, and the phase transition (tetragonal to cubic) occurs, leading to enormous variability in the electric and spectroscopic features of the material. [ 34,35 ] Therefore, it is of crucial importance to determine the crystal symmetry transformation and the corresponding temperature in a noninvasive, rapid and simple way. [ 35–38 ]…”

Local Structure Engineering in Lanthanide-Doped Nanocrystals for Tunable Upconversion Emissions

“…For the majority of materials, the lattice expands with increasing temperature, accompanied by potential ionic disordering, defect formation, polymorphic transformation, etc. In practice, temperature influences the upconversion emissions from many aspects, including local structure, 113 electron−phonon coupling, 114 surface status, 115 and thermal population that complies with Boltzmann distribution law. 116 The influences from the local structure are emphasized in this section.…”

Mechanical-load and temperature-engendered degradation of α-CsPbI3: reactive molecular dynamics simulation

“…The bonds of a-CsPbI 3 are stretched slightly along the direction of applied pulling forces prior to the formation of cracks or voids in the materials for energy compensation, which is similar to an earlier observation for the transformation of a cubic to a tetragonal structure with increasing potential energy. 42,43 It is also observed that the magnitude of the pulling force influences the initiation of cracking in the material. Crack initiation occurs nearly 20 times faster at high F z values (7 pN and 35 pN) than at low F z values (0.007 pN and 0.07 pN).…”