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). Issue 46 (5th December 2018)

• Record Type: Journal Article
• Authors: Cordes, Niklas; Bräuniger, Thomas; Schnick, Wolfgang
• Is Part Of: European journal of inorganic chemistry. Issue 46(2018)
• Page Start: 5019
• Page End: 5026
• Publication Date: 2018-12-05
• Subjects: Perovskite phases -- Ammonothermal synthesis -- Solvothermal synthesis -- High‐pressure chemistry -- Solid‐state structures; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201800827
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : Alkaline earth oxonitride perovskites EAM O2 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 NaN3 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 by scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. Crystals of 1–10 µm size were obtained. Optical band gap values were determined from UV/Vis measurements applying the Kubelka–Munk function with the Tauc method ( E g = 1.9 ‐ 2.1 eV). In addition to that, A Nb/Ta(O, N)3 with A = Ca, Sr, Ba, La were synthesized by ammonolysis reactions of the respective ternary oxide precursors. The products were investigated with 14 N solid‐state (MAS) NMR spectroscopy, all showing a single resonance at about 270 ppm. Abstract : EAM O2 N ( EA = Sr, Ba, M = Nb, Ta) oxonitride perovskite crystals were obtained in custom‐built high‐pressure autoclaves with the ammonothermal approach. Cube‐like crystals of up to 10 µm were analyzed with PXRD, SEM, EDX, UV/Vis. Furthermore, solid‐state 14 N NMR spectroscopic measurements were performed on AM (O, N)3 (with A = Ca, Sr, Ba, La; M = Nb, Ta).