Structural and magnetic properties of ceramics prepared by high-pressure high-temperature sintering of manganese-doped gallium nitride nanopowders

New Nitride Nanoceramics from Synthesis-Mixed Nanopowders in the Composite System Gallium Nitride GaN–Titanium Nitride TiN

“…For the theoretical Ti-imide Ti(NH) 2 , the deamination is accompanied by redox reactions as approximated by {Ti(IV)(NH) 2 } → Ti(III)N + 1/2 NH 3 + 1/4 H 2 + 1/4 N 2 . The general transamination/deamination chemistry was precedented in the 1980s [ 29 , 30 ] and, specifically, it was detailed by us for the dimethylamide derivatives of gallium [ 19 , 20 ], manganese-doped gallium [ 28 ], aluminum [ 20 ], mixtures of gallium and aluminum [ 20 , 31 ], and mixtures of aluminum and titanium [ 32 ]. It was also demonstrated to work for some trimethylsilylamides as reported for the preparation of manganese nitride η -Mn 3 N 2 from Mn-bis(trimethylsilyl)amide [ 35 ].…”

“…The H v values in Table 3 can be compared to the individually sintered nitrides. In this regard, the relevant pure h-GaN nanoceramics made by us from GaN_800_sint_650 and GaN_800_sint_1000 showed H v ’s of 13.6/15.0 and 10.0 GPa, respectively, whereas those made from GaN_950_sint_650 and GaN_950_sint_1000 showed, respectively, H v ’s of 10.6 and 17.4 GPa [ 28 ]. It is interesting to note that the H v values for the GaN nanoceramics were in most cases larger than the reference literature value of 11 GPa [ 46 ].…”

“…Upon ampoule opening, the powders were removed and briefly handled in air prior to high-pressure and high-temperature sintering, as described earlier [ 27 , 28 , 31 , 32 ]. Specifically, the powders were sintered for 3 min in a high-pressure torroid cell at 650, 1000, and 1200 °C under pressure of 7.7 GPa, yielding dark brown/golden or gray ceramic pellets, D = 4 mm, thickness ca.…”

“…We have developed throughout the years several preparation methods for nitride nanopowders such as GaN [16,[19][20][21][22][23][24], AlN [20,21], and TiN [25,26], as well as for some related composites, in many cases via alternative precursor routes. Furthermore, we described for the first time the no-additive sintering of pure [27] and Mn-doped/magnetic GaN nanopowders [28] with controlled recrystallization toward mechanically robust nanoceramics. Moreover, we recently reported on no-additive HP-HT sintering of two of these nitrides binary composite systems, i.e., GaN-AlN and TiN-AlN, applying a similar precursor chemistry scheme [20,29,30].…”

Convenient synthesis of nanocrystalline powders of phase-pure manganese nitride η-Mn3N2

“…In the related area, possibility of forming a diluted magnetic semiconductor with a sufficiently high Curie temperature by manganese-doped gallium nitride GaN is crucial in the anticipated spintronics semiconductor materials [6,7]. In the latter aspect that is of special interest to us, the knowledge of pure reference systems including various magnetic manganese nitrides is prerequisite [8][9][10][11] and this was a driving force behind the present study.…”