Synthese und Struktur von Ba₁₀[Ti₄N₁₂], ein ternäres Nitrid mit vierkernigen cyclischen Nitridotitanat‐Ionen

Abstract

Ba10[Ti4N12] entsteht als äußerst hydrolyseanfälliges rotbraunes Pulver aus Ba3N2, TiN und N2 bei 980°C. Es kristallisiert triklin in der Raumgruppe P1 mit den Gitterkonstanten a = 644,3(4); b = 942,9(7); c = 966,9(7) pm, α = 106,37(4)°; β= 102,22(4)°; γ = 108,56(4)°, Z = 1. Die Kristallstruktur ist aus Ba2+‐Kationen und vierkernigen cyclischen Nitridotitanat(IV)‐Anionen aufgebaut. In den Anionen sind vier TiN4‐Tetraeder über je zwei Ecken zu einem zentrosymmetrischen Ring verknüpft. Die Ringe sind längs [100] zu Röhren gestapelt. Die TiN‐Abstände liegen zwischen 192 und 199 pm.

Synthesis and Structure of the New Ternary Nitride SrTiN2

“…The number of known ternary nitridotitanates is small, and only one ternary alkaline earth titanium nitride, Ba 10 Ti 4 N 12 , has been previously reported. 40 The titanium coordination in this compound is tetrahedral; four TiN 4 tetrahedra are vertexconnected to form unusual cyclic nitridotitanate(IV) anions. The average Ti-N bond length in Ba 10 Ti 4 N 12 is 1.95(4) Å, smaller than that in SrTiN 2 .…”

“…The average bond length in Li 5 TiN 3 is 2.02 Å, marginally larger than the mean Ti−N distance in the barium ternary nitride but very similar to the mean Ti−N bond length in SrTiN 2 . At this stage, it is perhaps worth drawing attention to the short Ti−Ti distances (3.063(1) Å) in SrTiN 2 , which are only slightly longer than the intermetallic distances seen in Ti metal (α-Ti, ∼2.90 Å; β-Ti, ∼2.87 Å) , and binary titanium nitrides (∼2.85 to ∼2.99 Å) 36-39 and shorter than the distances in the other known ternary compounds Li 5 TiN 3 (∼3.43 Å) 41 and Ba 10 Ti 4 N 12 (∼3.75 Å) …”

“…At this stage, it is perhaps worth drawing attention to the short Ti-Ti distances (3.063(1) Å) in SrTiN 2 , which are only slightly longer than the intermetallic distances seen in Ti metal (R-Ti, ∼2.90 Å; β-Ti, ∼2.87 Å) 42,43 and binary titanium nitrides (∼2.85 to ∼2.99 Å) [36][37][38][39] and shorter than the distances in the other known ternary compounds Li 5 TiN 3 (∼3.43 Å) 41 and Ba 10 Ti 4 N 12 (∼3.75 Å). 40 The coordination of strontium to nitrogen could be viewed as 9-fold, as for barium in BaZrN 2 , 23 but is effectively only 5-fold with the longer "basal" distances of the Sr-N polyhedron being over 3.2 Å (3.2412(8) Å). The coordination geometry thus simplifies to a square-based pyramidal arrangement.…”

Group V and VI Alkali Nitridometalates: A Growing Class of Compounds with Structures Related to Silicate Chemistry

“…Trigonal planar species are reported for V, Cr, Mn, − Fe, ,− Co, and Ga . However Al, ,, Ti, , Zr, − Hf, , V, Nb, Ta, Cr, Mo, and W prefer higher coordination numbers in nitridometalates with tetrahedral or octahedral coordination environments. In one exception, zirconium, is found in a quadratic pyramidal coordination mode in Ba[ZrN 2 ] …”

Ion Substitution Effect on Defect Formation in Two-Dimensional Transition Metal Nitride Semiconductors, AETiN2 (AE = Ca, Sr, and Ba)

“…The high-density V N defects are generated only under the low-N pressure conditions, while the O N defects are generated under both N-poor and N-rich conditions (especially for SrTiN 2 and BaTiN 2 ). In addition, O N2 is easily formed in BaTiN 2 than in SrTiN 2 even under N-moderate conditions, suggesting the higher difficulty in obtaining pure BaTiN 2 samples and explaining the absence of reports on the synthesized BaTiN 2 compounds . Generally, nitrides are synthesized under N-rich conditions; hence, O N defects may be a serious problem in obtaining high-purity AE TiN 2 semiconductors.…”