Ammonothermal Synthesis of EAMO₂N (EA = Sr, Ba; M = Nb, Ta) Perovskites and ¹⁴N Solid‐State NMR Spectroscopic Investigations of AM(O,N)₃ (A = Ca, Sr, Ba, La)

Abstract

Alkaline earth oxonitride perovskites EAMO 2 N (EA = Sr, Ba; M = Nb, Ta) were synthesized by the ammonothermal method at temperatures of 900 K and maximum pressures of up to 300 MPa in custom-built autoclaves starting from Nb or Ta and Sr or Ba metals. The reactions were performed under ammonobasic conditions using NaN 3 and NaOH as mineralizers. Powder X-ray diffraction and Rietveld refinement were used to determine the crystal structures. The elemental composition and morphology of the obtained products were investigated [a] 5020 group "Chemistry and Technology of the Ammonothermal Synthesis of Nitrides" (FOR 1600), project SCHN377/16-2, as well as the Fonds der Chemischen Industrie (FCI). We would like to thank Christian Minke for EDX, SEM, and NMR spectroscopic measurements, as well as Lukas Bauer (both at the Department of Chemistry of LMU Munich) for synthetic assistance.

Ammonothermal Synthesis of the Mixed‐Valence Nitrogen‐Rich Europium Tantalum Ruddlesden‐Popper Phase EuIIEuIII2Ta2N4O3

“…Such a platelet morphology has not yet been observed in other ammonothermal reactions, but could be found in the ammonolysis product of LaTiNO 2 , . The morphology of cuboid crystals were already observed in other ammonothermal reactions of nitride oxide perovskites , , , , . SEM images show that there are more cuboid‐shaped crystals in the center of the liner and platelets were found almost exclusively at the bottom of the liner.…”

“…Non‐condensed octahedral anions Ta(O 1– x ,N x ) 6 (7+6 · x )– , which react to NaTa(O 1– x N x ) 3– x , might form as well . However, the intermediates/reactive species are still a matter of debate , , . Compared to other ammonothermal reactions with lanthanides and tantalum, only the Ruddlesden‐Popper phase Eu II Eu III 2 Ta 2 N 4 O 3 (see crystal structure determination ) could be synthesized.…”

“…Recently, the ammonothermal approach has again been utilized for explorative synthetic solid‐state chemistry of novel complex nitrides, e.g. CaGaSiN 3 , ZnSiN 2 , ZnGeN 2 , Zn 2 PN 3 as well as nitride oxide perovskites such as Ln TaN 2 O with Ln = La, Ce, Pr, Nd, Sm and Gd and EAM NO 2 with EA = Sr, Ba and M = Nb, Ta , . Novel materials with mixed anions such as nitride oxides came into research focus in the last decade.…”

Ammonothermal Synthesis of Ba2PO3N – An Oxonitridophosphate with Non‐Condensed PO3N Tetrahedra

“…InN, II‐IV‐N 2 (II = Mg, Mn, Zn; IV = Si, Ge), CaGaSiN 3 or Ca 1– x Li x Al 1– x Ge 1+ x N 3 ( x ≈ 0.2)] and oxide nitride perovskites [e.g. EAM O 2 N ( EA = Sr, Ba; M = Nb, Ta)] as well . Most recently, the syntheses of numerous nitridophosphates with different degrees of condensations κ (i.e.…”

“…EAMO 2 N (EA = Sr, Ba; M = Nb, Ta)] as well. [12][13][14][15][16][17][18] Most recently, the syntheses of numerous nitridophosphates with different degrees of condensations κ (i.e. atomic ratio of tetrahedra centers to ligand) could be realized.…”