Recent studies have shown that many challenges encountered in conventional single crystal growth methods, including high production costs, can be overcome by using the solid-state single-crystal growth(SSCG) approach,...Recent studies have shown that many challenges encountered in conventional single crystal growth methods, including high production costs, can be overcome by using the solid-state single-crystal growth(SSCG) approach, which has been recognized as a simple and cost-effective alternative for obtaining single crystals. In this work, YAlO(YAG) and Nd-doped YAG(Nd:YAG) single crystals were grown via the SSCG method using spark plasma sintering(SPS). The growth of single crystals was initiated at the surface of(110) YAG single-crystal seeds embedded inside YAG and Nd:YAG powder beds, and this growth continued as the surrounding polycrystalline matrix was converted into a single crystal. The application of external pressure during the SPS process has been found beneficial for reducing the porosity of the grown single crystals. Moreover, high Nddoping levels had a positive effect on the conversion kinetics,with a growth rate of almost 50 μm/h, which increased the driving force for single-crystal growth through the solute drag effect. EDS elemental mapping and line scans confirmed the compositional uniformity of the grown single crystals, while EBSD images verified their crystallization in the(110) direction. The obtained results confirm the strong potential of the SSCG technique coupled with SPS for the growth of undoped and highly doped YAG single crystals with excellent quality.展开更多
In this study we fabricated, for the first time, magnesium gallate (MgGa_(2)O_(4), a partially inverted spinel) transparent ceramics, both undoped and doped with 1 at% Ni. The specimens were derived from in-house prep...In this study we fabricated, for the first time, magnesium gallate (MgGa_(2)O_(4), a partially inverted spinel) transparent ceramics, both undoped and doped with 1 at% Ni. The specimens were derived from in-house prepared powder, with a crystallite size of ∼10 nm (by wet chemistry) and densified by pulsed electric current sintering (PECS;peak temperature 950 ℃ for 90 min). Densification levels of 99.84% and 99.52% of theoretical density were attained for doped and undoped materials, respectively. Doping with Ni was seen to marginally improve the densification level. Quite transparent specimens were produced: the best showing transmission of ∼89% of the theoretical level (thickness t = 0.85 mm). The absorption spectra revealed that the dopant was accumulated as Ni^(2+) in the octahedral sites of the lattice, as occurs in single-crystal specimens. After excitation at 980 nm, the doped disks exhibited a wide fluorescence band centered at 1264 nm.展开更多
基金the NSF grant (No.1554094) for supporting the research。
文摘Recent studies have shown that many challenges encountered in conventional single crystal growth methods, including high production costs, can be overcome by using the solid-state single-crystal growth(SSCG) approach, which has been recognized as a simple and cost-effective alternative for obtaining single crystals. In this work, YAlO(YAG) and Nd-doped YAG(Nd:YAG) single crystals were grown via the SSCG method using spark plasma sintering(SPS). The growth of single crystals was initiated at the surface of(110) YAG single-crystal seeds embedded inside YAG and Nd:YAG powder beds, and this growth continued as the surrounding polycrystalline matrix was converted into a single crystal. The application of external pressure during the SPS process has been found beneficial for reducing the porosity of the grown single crystals. Moreover, high Nddoping levels had a positive effect on the conversion kinetics,with a growth rate of almost 50 μm/h, which increased the driving force for single-crystal growth through the solute drag effect. EDS elemental mapping and line scans confirmed the compositional uniformity of the grown single crystals, while EBSD images verified their crystallization in the(110) direction. The obtained results confirm the strong potential of the SSCG technique coupled with SPS for the growth of undoped and highly doped YAG single crystals with excellent quality.
基金The authors gratefully acknowledge the National Science Foundation CAREER Grant(No.1554094)Office of Naval Research(No.N00014-17-1-2548)for funding this researchPart of this material(Raman data)is based upon work supported by the National Science Foundation(No.DMR-1626164).
文摘In this study we fabricated, for the first time, magnesium gallate (MgGa_(2)O_(4), a partially inverted spinel) transparent ceramics, both undoped and doped with 1 at% Ni. The specimens were derived from in-house prepared powder, with a crystallite size of ∼10 nm (by wet chemistry) and densified by pulsed electric current sintering (PECS;peak temperature 950 ℃ for 90 min). Densification levels of 99.84% and 99.52% of theoretical density were attained for doped and undoped materials, respectively. Doping with Ni was seen to marginally improve the densification level. Quite transparent specimens were produced: the best showing transmission of ∼89% of the theoretical level (thickness t = 0.85 mm). The absorption spectra revealed that the dopant was accumulated as Ni^(2+) in the octahedral sites of the lattice, as occurs in single-crystal specimens. After excitation at 980 nm, the doped disks exhibited a wide fluorescence band centered at 1264 nm.
