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This study provided the first in-depth investigation of the effects of large dopant incompatibility (Pr3+ and La3+ ions) on the small host lattice element (Lu3+) in Lu 3 Al 5 O 12 (LuAG) single crystal. The growth of such complex crystals from the melt presented many challenges. By engineering the ionic radius ratio of RE- and M-site cations, a single-crystal phase stabilized by configurational entropy was achieved. This investigation elucidated the crystallization behavior of configurationally disordered rare-earth aluminum garnet oxide (Lu 1−x−y Pr x La y) 3 Al 5 O 12 from the melt and characterized its functional properties, including microstructural, optical, photoluminescence, and scintillation properties, between 5 and 300 K. Relaxation of the imposed strain energy led to local perturbations and destabilization of the garnet structure. Multielemental EDS mapping, micro-Raman spectroscopy, and thermoluminescence revealed the mechanism by which atomic size mismatch drove a smooth transition from the garnet to the perovskite phase in high entropy garnets. The optical, photoluminescence, and scintillation measurements provided fundamental insights into property changes driven by incompatibility doping. Standard and modified Judd-Ofelt theory analysis of absorption spectra determined the phenomenological Judd-Ofelt parameters Ω λ and radiative lifetimes. Atomic size mismatch engineering offers a promising approach to overcoming the limitations of conventional eutectic synthesis methods. • Perovskite inclusions, driven by atomic size mismatch, extend from rim to core. • Controlled incompatible La3+,Pr3+ codoping in LuAG modify functional properties. • Scintillation light yield improved up to 30% in La3+ codoped LuAG:Pr crystals. • (La,Pr)AlO 3 perovskite forms due to size mismatch of La3+ and Pr3+ with Lu3+. • Lattice disorder affects the intensity ratio of Pr³⁺ 5d→4 f and 4 f→4 f emissions. [ABSTRACT FROM AUTHOR]

Here, we report superconducting Mg11B 2 wires made by using the internal Mg diffusion technique with isotopic amorphous nano boron (11B) as the precursor material. We show the influence of annealing temperature and isostatic pressure of 0.1 MPa and 1.1 GPa on Mg diffusion into 11B layer, microstructure of superconducting filament, critical current density (J c) at 20 K and 25 K, critical temperature (T c) and irreversible magnetic induction (B irr) in mono (single-core) - and multi-filament Mg11B 2 wires. Our research shows that thermal treatment at 700 °C and 0.1 MPa for 60 min yields a superconducting phase with low T c , B irr and J c in single-core Mg11B 2 wire. A higher annealing temperature (740 °C and 0.1 MPa for 60 min) significantly accelerates the diffusion of Mg into the 11B layer and increases the T c , B irr and J c. However, the distribution of Mg in 11B layer is very heterogeneous (places with high and low Mg concentration). This leads to heterogeneity in the superconducting material and inhomogeneous T c , B irr and J c. Further studies showed that higher annealing temperatures at 770 °C and 800 °C significantly accelerates the diffusion of Mg into the 11B layer and leads to the increase of T c , B irr and J c in single-core Mg11B 2 wire. In single-core wire annealing treatment under isostatic pressure of 1.1 GPa for 60 min at temperature of 800 °C it causes Mg penetrates into the 11B layer very heterogeneously and large amount of 11B remains unreacted. However, the same heat treatment at 800 °C and 1.1 GPa for 60 min in multi-filament wires leads to a complete Mg synthesis reaction with the 11B layer. This leads to increase B irr and J c. This work shows that the formation and accumulation of pinning centers is essential to further increase J c in Mg11B 2 wires. [Display omitted] • The Mg diffusion in IMD MgB 2 wires with nano isotopic boron (11B) is much slower than in IMD MgB 2 wires with nano boron. • Annealing temperature 770 °C and 0.1 MPa leads to complete synthesis reaction of Mg with nano 11B in IMD MgB 2 wires. • Thermal treatment under pressure of 1.1 GPa slows down the diffusion of Mg to nano 11B in single core IMD MgB 2 wires. • Thermal treatment under of 1.1 GPa significantly accelerates diffusion of Mg to nano 11B in multi-filament IMD MgB 2 wires. • Thermal treatment at 800 °C under low and high isostatic pressures decrease the density of the pining centers. [ABSTRACT FROM AUTHOR]

• Mg2+ codoping effect on the atoms segregation in GAGG:Ce single crystal studied. • The formation of defects in Mg2+ and Ce3+ codoped GAGG crystals discussed. • The luminescence quenching mechanism in Mg2+ codoped proposed. • The charge compensation mechanism discussed. • Mg2+ codoping influence on the scintillation and luminescence properties investigated. The undoped, Mg2+ doped, Ce3+ doped as well as Mg2+:Ce3+ codoped Gd 3 Al 2 Ga 3 O 12 crystals were grown from the melt by the micro-pulling down method. Ce3+ and Mg2+ ions were codoped in a wide concentration range. A study of Mg2+ ion concentration effect on the luminescence and scintillation properties as well as segregation of atoms and defects creation processes were carried out. Mg2+ doping in Gd 3 Al 2 Ga 3 O 12 led to the creation of O O • defects localized next to Mg2+ sites due to charge imbalance compensation. Consequently, neutral (Mg Ga/Al/Gd O O) x defects were formed. In Ce3+ doped crystals, Mg2+ codoping changed the valence state from Ce3+ to Ce4+ to maintain charge neutrality. Hence, additional neutral (Ce Gd • -Mg Ga/Al/Gd ′) x and (Ce Gd -Mg Ga/Al/Gd O O) x defects appeared. Moreover, Mg2+ induced charge imbalance in GAGG crystal might also be compensated by the formation of oxygen vacancies (V O •• ). The Mg2+ ions imposed defects deteriorated the segregation of atoms. Accordingly the radial inhomogeneity of the crystals was diminished. The presence of stable Ce4+ and defects imposed by Mg2+ ions codoping were proved by absorption, photoluminescence, and scintillation decay time analysis. Hence, Mg2+ codoping resulted in quenching of the Ce3+ luminescence, acceleration of scintillation response, reduction of light yield, and thermally stimulated luminescence. The mechanism explaining a strong luminescence quenching with increasing Mg2+ ions concentration was proposed. [ABSTRACT FROM AUTHOR]