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• La-doped SrTiO 3 /TiO 2 eutectic crystals were grown by a micro-pulling-down method. • Grown crystals were composed of the TiO 2 rod phase in the SrTiO 3 matrix phase. • Diameter of TiO 2 rods systematically decreased as the growth rate was increased. • Grown crystal exhibited a lower thermal conductivity than the SrTiO 3 single crystal. • ZT s of crystals grown at 0.02 and 0.5 mm/min were 0.015 and 0.025, respectively. La-doped SrTiO 3 /TiO 2 (La:STO/TO) eutectic crystals were grown by a micro-pulling-down method at various growth rates to control the eutectic morphology and thermoelectric properties. The La:STO/TO eutectic crystals were composed of a TiO 2 (TO) rod phase in the SrTiO 3 (STO) matrix phase for all growth rates. The diameter of the TO rod phase systematically decreased as the growth rate was increased, according to the Jackson–Hunt model, and the diameter reached approximately 1 μm at a growth rate of 1 mm/min. The La:STO/TO eutectic crystal exhibited a lower thermal conductivity than the Nb:STO single crystal, owing to the decrease in the lattice thermal conductivity by phonon scattering at boundaries in the eutectic morphology. The figures of merit, ZT s, of the La:STO/TO eutectic crystals grown at 0.02 and 0.5 mm/min growth rates were 0.015 and 0.025, respectively. The faster growth rate led to an increased ZT, owing to the decrease in electrical resistivity. [ABSTRACT FROM AUTHOR]

• Phase diagram of BaI 2 -LuI 3 system was created and it was eutectic type diagram. • BaI 2 -LuI 3 system had an eutectic point around 77.5 mol%BaI 2 /22.5 mol%LuI 3. • BaI 2 /LuI 3 eutectic crystal and Ce-doped BaI 2 /LuI 3 eutectic scintillator were grown. • The BaI 2 /LuI 3 eutectic crystal was composed of LuI 3 rod phase and BaI 2 matrix phase. The phase diagram of the BaI 2 -LuI 3 system was created using powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis, and a eutectic scintillator crystal was grown by the halide-vertical bridgman (H-VB) method. The results of XRD patterns and DSC curves showed that the phase diagram of the BaI 2 -LuI 3 system had a eutectic point around 77.5 mol% BaI 2 /22.5 mol% LuI 3 , and no new compound was generated from BaI 2 and LuI 3. The 77.5 mol% BaI 2 /22.5 mol% LuI 3 eutectic crystal was composed of BaI 2 in rod phase and LuI 3 in matrix phase. In addition, the Ce-doped 77.5 mol% BaI 2 /22.5 mol% LuI 3 specimen showed emission peaks originating from 5d–4f transition of Ce3+ ion in the X-ray radioluminescence (XRL) spectrum and the decay time under γ-ray irradiation was approximately 38 ns. [ABSTRACT FROM AUTHOR]

• Ce doped LaCl 3 /AECl 2 (AE = Mg, Ca, Sr) eutectics were grown by BS method. • In case of AE = Mg, Ca, eutectic with PSSFs structures were observed. • The Ce:LaCl 3 /CaCl 2 eutectic showed Ce3+ 4f-5d emission at 345 nm. • The light output of Ce:LaCl 3 /CaCl 2 under 137Cs was 9000 photons/MeV. • The scintillation decay time under 137Cs was 26.8 ns (26%) and 282 ns (74%). Ce-doped LaCl 3 /AECl 2 (AE = Mg, Ca, Sr) system eutectics were explored. Ce-doped LaCl 3 / AECl 2 (AE = Mg, Ca, Sr) eutectics were grown using the Bridgman–Stockbarger method in quartz ampoules. In the case of AE = Mg, Ca, eutectics with submicron-diameter phase-separated scintillator fibers (PSSFs) structure were observed. In the case of AE = Sr sample, a solid solution of La 0.708 Sr 0.292 Cl 2.708 was observed. The plate sample from the grown eutectics has some transparency. The grown eutectic structure showed a mixture of rods and plates shape. This mixed structure was aligned with a length of around 100–400 μm. The Ce:LaCl 3 /CaCl 2 eutectic showed 345 nm emission ascribed to Ce3+ 4f-5d transition under X-ray excitation. The Ce:LaCl 3 /CaCl 2 sample resulted in the highest light output of 9,000 photon/MeV, which is comparable to the previously reported eutectic scintillator Ce:GdAlO 3 /α-Al 2 O 3 , 9500 photon/MeV. Scintillation decay time of the Ce:LaCl 3 /CaCl 2 sample under 662 keV gamma-ray excitation was 26.8 ns (26%) and 282 ns (74%). [ABSTRACT FROM AUTHOR]

• A novel ternary CsI/KI/KCl eutectic scintillator is reported. • Directionally solidified eutectic was grown using the Bridgman–Stockbarger method. • The expected Tl+ emission peak near 486 nm was observed in the CsI phase. • The decay time of the eutectic was 313 ns. • The light output of the eutectic was approximately 22,000 photons/MeV. In this study, Tl:CsI/KI/KCl eutectic scintillators were grown using the Bridgman–Stockbarger method by unidirectional solidification. The eutectic phases were uniformly distributed in the transverse direction and were slightly aligned along the growth direction. The Tl:CsI scintillator phase was grown as a matrix, which was then used for creating optical waveguides of the scintillation light. The expected Tl+ emission peak was observed at 486 nm under X-ray excitation and cathodoluminescence; this was attributed to the self-trapped exciton perturbed by TI+ in Tl:CsI. The decay time of the Tl:CsI/KI/KCl eutectic was 313 ns, and its light output was estimated to be 22,000 photons/MeV. [ABSTRACT FROM AUTHOR]