Comparison of the thermophysical and optical properties of ceramics based on YSAG: Yb,Er solid solutions with different forms of crystal lattice disorder

Abstract

Optical ceramics with 50 at.% Sc in both dodecahedral ({Y1•17Er0.03Yb0.3Sc1.5}[Al1.8Sc0.2]Al3O12, {Y1.2Yb0.3Sc1.5}[Al1.8Sc0.2]Al3O12) and octahedral ({Y2•52Er0.03Yb0.3Sc0.15}[Al1.0Sc1.0]Al3O12, {Y2.55Yb0.3Sc0.15}[Al1.0Sc1.0]Al3O12) sites of the garnet structure were synthesized using the non-reactive vacuum sintering method. Analysis of the phase composition, thermal diffusivity, transmission in the visible and IR regions of the spectrum, as well as luminescent properties (Stokes and anti-Stokes luminescence, luminescence decay kinetics) revealed clear correlations with the chemical composition of ceramics. It has been determined that solid solutions in which Y3+ cations are partially replaced by Sc3+ cations, compared to solid solutions in which Al3+ cations in the octahedral site are partially replaced by Sc3+, are characterized by lower crystal lattice parameters (11.883 ± 0.004 Å and 12.153 ± 0.005 Å); lower thermal conductivity values (4.72 W/(m•K) and 5.9 W/(m•K)); higher characteristic vibration frequencies of structural groups; shorter lifetimes of excited states of Yb3+ (1.41 μs and 1.56 μs for YSAG:Yb; 0.42 μs and 0.65 μs for YSAG:Yb,Er) and Er3+ (8.6 μs and 9.2 μs) cations; higher efficiency of energy transfer from Yb3+ to Er3+. The results clearly indicate that solid solutions with high concentrations of Sc3+ cations in the dodecahedral site can also be effective matrices for Yb3+ and Er3+ cations compared to solid solutions with a predominant introduction of scandium in the octahedral site.