93Nb NMR Study of (K, Na)NbO3‐Doped SiO2–Na2O–Al2O3 Glasses. Issue 9 (24th May 2022)

• Record Type: Journal Article
• Authors: Otsuka, Takahito; Cicconi, Maria Rita; Dobesh, David; Schroeder, Barbara; Hayakawa, Tomokatsu
• Other Names: Miyazaki Hidetoshi guestEditor.; Hayashi Koichi guestEditor.; Kakimoto Ken-ichi guestEditor.
• Is Part Of: Physica status solidi. Volume 259:Issue 9(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-05-24
• Subjects: aluminosilicate glasses -- glass-ceramics -- local structure analysis -- Nb NMR -- NbO6 octahedra -- nuclear magnetic resonance -- perovskites; Solid state physics -- Periodicals; Solids -- Periodicals; Atomic structure -- Periodicals; 530.41
• DOI: 10.1002/pssb.202200016
• Languages: English
• ISSNs: 0370-1972

Abstract

Abstract : Aluminosilicate glasses containing octahedral NbO6 units are developed for future applications as optical materials. Soda‐aluminosilicate glasses doped with Nb‐based alkaline perovskite crystals (K0.5 Na0.5 NbO3 [KNN]) at different doping levels (2–30 mol%) are studied by 93 Nb nuclear magnetic resonance (NMR) spectroscopy. The Al2 O3 concentration in the starting soda‐aluminosilicate glass matrix is varied from 5 to 17 mol% to investigate the influence of the composition of local Nb structures with 4–5, 6, and 7–8 fold‐oxygen coordination on the optical properties of the glasses. The chemical shifts are analyzed by comparison with the 93 Nb NMR data of reference crystals, including KNN, to determine the feasibility of producing more NbO6 octahedra in the aluminosilicate glasses, where these octahedra are expected to promote the development of optically active Nb‐glass‐ceramics. The data show that both glass polymerization and KNN content influence the Nb local environment. Therefore, an appropriate amount of Al2 O3 combined with an adequate doping level of the KNN perovskite is required to achieve the desired optical features. Contrary to expectations, a higher KNN doping level is achieved with the starting depolymerized soda‐aluminosilicate glass containing 5 mol% Al2 O3, leading to perovskite‐like structures of NbO6 octahedra in the resultant glass system. Abstract : 93 Nb magic‐angle‐spinning nuclear magnetic resonance (MAS NMR) spectra of (100 − x )(66.6SiO2− y Al2 O3 −(33.4 − y )Na2 O)− x K0.5 Na0.5 NbO3 glasses are studied to acquire information on the local structures around the niobium ions. 93 Nb NMR spectroscopy reveals that Nb ion exists as NbO6, mainly, and the ratio of NbO n ( n = 4–8) polyhedron in the glasses changes depending not only on the Al2 O3 /Na2 O ratio, but also on the K0.5 Na0.5 NbO3 doping amount.