Structure and Dynamics of LiPON and NaPON Oxynitride Phosphate Glasses by Solid-State NMR

Abstract

Oxynitride phosphate glasses are a subfield of phosphate-based glasses, where part of the oxygen of the network has been replaced by nitrogen, in a process commonly called nitridation, of the phosphate melt. Because of this, the properties of the glasses are greatly enhanced, notably mechanical and chemical resistance, which has resulted in an important field with applications in glass-to-metal sealing or as electrolytes for solidstate batteries when processed as thin films. Whereas the properties of oxynitride phosphates have been thoroughly researched in view of their prospected applications, the elucidation of their structure remains uncomplete in some aspects, notably in the way that the network building groups are interconnected as well as from the point of view of the role of the modifiers onto the nitrided network structure. In the present work, 1D, 2D, REDOR, and INADEQUATE NMR experiments have been complemented with high-temperature NMR of lithium and sodium oxynitride phosphate glasses to study the structural arrangement of the building units and its evolution with temperature. The results have evidenced that the network organization adopted by the glasses distinctively depends on the nature of the modifier cation. However, the results exclude any significant phase separation or segregation of oxide and oxynitride regions, despite some clustering of nitride species may be occurring, mostly in the lithiumcontaining glasses.

NaPON Doping of Na4P2S7 Glass and Its Effects on the Structure and Properties of Mixed Oxy-Sulfide-Nitride Phosphate Glass

“…A shoulder arises with increasing x at ∼2 ppm and is attributed to MON end member SRO groups, PO 3 N 0.33 2– anions, where nitrogen is N t . Glasses containing both N d and N t nitrogen, x ≤ 0.2, show two absorption peaks at −7 and −12 ppm and are assigned to PO 2.5 N 0.33 1– SRO groups with N t nitrogen and PO 2 N 0.67 1– with N d nitrogen ,,, SRO groups. For glasses x ≥ 0.3, which contain only N t nitrogen (see the nitrogen XPS spectra above), show the same absorption peak appears at −7 ppm, but also a new species appearsd at −15 ppm assigned to PO 1.5 N 0.67 1– SRO groups, where both nitrogens are N t coordinated. ,, Lastly, an absorption peak at −28 ppm grows in intensity with increasing x and is assigned to the PO 2 N 0.33 anion SRO, with the N t nitrogen. , …”

Structure‐mechanical properties correlation in bulk LiPON glass produced by nitridation of metaphosphate melts

“…Figure (3A) shows the 31 P MAS NMR spectra for the nitrided glasses from N/P = 0 to 0.75. The spectra of the un‐nitrided glass show a single strong peak arising from the expected P 2 SRO units of LiPO 3 at −24.4 ppm, and a very small peak arising from P 1 SRO units of P 2 O 7 −2 located at −5.3 ppm 34,35 . This latter peak presumably arises from the unavoidable but very small amount of water in these glasses arising from the decomposition reaction shown in Equation (3) above.…”

“…The spectra of the un-nitrided glass show a single strong peak arising from the expected P 2 SRO units of LiPO 3 at −24.4 ppm, and a very small peak arising from P 1 SRO units of P 2 O 7 −2 located at −5.3 ppm. 34,35 This latter peak presumably arises from the unavoidable but very small amount of water in these glasses arising from the decomposition reaction shown in Equation ( 3) above. This residual water content acts as a chain terminator to form terminal P 1 units of the form -P(O)(OLi)(OH).…”

“…These changes are a result of the formation of PO 3 N −1 and PO 2 N 2 −1 species with added nitrogen which have P MAS NMR peaks located approximately at -13 ppm and -2 ppm, respectively. 34 The structures are given in Figure 4.…”

Medium-Range Ordering in the Ionic Glass Electrolytes LiPON and LiSiPON

“…Efforts to understand the structure of LiPON date back to its discovery in the early 1990s. Initial efforts relied on X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, infrared spectroscopy (IR), and nuclear magnetic resonance. − Many of these investigations have centered around the effect of substituting N into the amorphous Li 3 PO 4 structure. Based on XPS similarities with low alkali phosphate glass, some researchers came to the faulty assumption that N forms primarily double and triple bridges.…”