Synthesis and Structure of Two New Quaternary Nitrides: Li3Sr2MN4(M=Nb, Ta)

✍ Scribed by X.Z. Chen; H.A. Eick

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 331 KB
• Volume: 130
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1996.7202

✦ Synopsis

Two new quaternary nitrides, Li 3 Sr 2 M N (M‫؍‬Nb, Ta) have been synthesized from Li, Sr, and Nb or Ta metals under a flowing Ar-NH 3 atmosphere at 800°C under ambient pressure. The structures, determined by single crystal X-ray diffraction, are orthorhombic, space group Pnnm (No. 58) with Z‫,4؍‬ and have lattice parameters a‫)6(317.8؍‬ A s , b‫)4(700.9؍‬ A s , c‫؍‬ 7.006(5) A s and a‫)6(007.8؍‬ A s , b‫)4(400.9؍‬ A s , c‫)3(000.7؍‬ A s for M‫؍‬Nb and Ta, respectively. Refinement based upon F yielded R‫330.0؍‬ and R w ‫630.0؍‬ for M‫؍‬Nb and R‫530.0؍‬ and R w ‫540.0؍‬ for M‫؍‬Ta. The structures are isotypic with Na 2 Li 3 MO 4 , M‫؍‬Fe, Ga. The M and two independent Li atoms are tetrahedrally coordinated by N atoms. Each M N 4 tetrahedron connects three Li(2)N 4 tetrahedra, one by edge-sharing and two by corner-sharing, to form a two-dimensional layer in the bc plane. These layers are linked together by Li(1) atoms to form the three-dimensional structure. The two Sr atoms occupy channels formed by N atoms along the c direction. Crystalline Li 3 Sr 2 NbN 4 was synthesized by heating a Li 3 N-Sr 2 NbN 3 mixture at 750°C under an Ar atmosphere. Magnetic susceptibility data for Li 3 Sr 2 NbN 4 between 4 and 300 K exhibit temperature independent paramagnetism.