New Ways to High-Quality Bulk Scandium Nitride

Abstract

ScN was prepared in three different ways leading to single phase samples with low oxygen content in a broad range of particle sizes. Synthesis from the elements provides, in an exothermic reaction, brownish transparent single crystals (rock-salt structure type, space group Fm3 hm, a ) 451.2(1) pm, Z ) 4, R int ) 0.034, R1 ) 0.013, wR2 ) 0.018). From a decomposition reaction of Li 3 [ScN 2 ] fine brown powders (particle size ≈ 1 µm) were obtained. Via nitridation of intermetallic Sc-In phases even nanoscaled (<200 nm) ScN can be produced. The emerging In was converted to InI 3 and removed at comparable low temperatures (T max ) 453 K) by sublimation or extraction. Thermodynamic considerations enlighten the process. Crystal structure refinements, density measurements, and chemical analyses show an atomic ratio close to the ideal composition ScN with only a small vacancy concentration in the N-sublattice for all samples. Still, metal-like behavior in the electrical resistivity was observed ((F(300 K) -F 0 ) 1.1 × 10 -4 Ωcm, temperature coefficient 2.7 × 10 -3 K -1 ). This interpretation is in accordance with the magnetic susceptibility (temperatureindependent paramagnetism χ 0 ≈ 4 × 10 -6 emu/mol) and the observed band gap of ∆E ) 2.10(2) eV. The oxidation behavior dependence on the particle size is analyzed.

Effect of impurities on morphology, growth mode, and thermoelectric properties of (1 1 1) and (0 0 1) epitaxial-like ScN films

“…The mass density deduced from the X-ray reflectivity measurements varies from 3.75(1) g cm -3 at low temperature to 4.09 (1) g cm -3 at high temperature. The densities obtained can be compared to the ScN bulk values of 4.25(2) [39]. The film deposited on c-plane Al2O3 do not exhibit a clear difference of the cell parameter when the TD increases from 700 C to 950 C with a value close to 4.504(4) Å.…”

Synthesis of Scandium Nitride Crystals from Indium–Scandium Melts

“…Figure shows the SEM images of the ScN crystals grown at different temperatures for the case of 10 at.% Sc concentration. Unlike the cuboid shape of the crystals prepared by the direct reaction of element Sc and N 2 , all of the crystals grown from indium flux exhibited a rounded shape which may arise from a high supersaturation of the solution. Based on the SEM images in Fig.…”

“…On the other hand, ScN particles have been also synthesized. Several authors have reported about the direct reaction of Sc metal with N 2 gas at high temperatures (1007–2060°C), resulting in several hundred micrometer‐sized gray–black or blue crystals. Niewa et al .…”

“…Niewa et al . also utilized another two methods for preparing ScN particles: (a) decomposition of Li 3 [ScN 2 ] at above 847°C, obtaining fine brown powders of about 1 μm, and (b) nitridation of the intermetallic In‐Sc phases, leading to nanoscaled ScN crystals . Although the ScN nanoparticles were obtained by the reaction of high Sc content of intermetallic Sc 3 In, Sc 2 In, Sc 5 In 3 , and Sc 3 In 5 with N 2 atmosphere, the supersaturation of ScN in indium is hard to control during the synthesis.…”

Metal‐Rich Ternary Perovskite Nitrides

“…For (Sc 3 N)In the transition from the hexagonal binary intermetallic compound to the cubic perovskite indicates a structure determining effect of the nitride ion, as discussed in more detail for the reversible case of related perovskite hydrides . All compounds ( R 3 N)In readily react with excess N 2 at elevated temperatures forming the binary rare‐earth metal nitride R N and In metal …”