Li₂CaSi₂N₄ and Li₂SrSi₂N₄ – a Synthetic Approach to Three‐Dimensional Lithium Nitridosilicates

Abstract

The quaternary lithium alkaline earth nitridosilicates

Lithium Ion Mobility in Lithium Phosphidosilicates: Crystal Structure, 7Li, 29Si, and 31P MAS NMR Spectroscopy, and Impedance Spectroscopy of Li8SiP4 and Li2SiP2

“…In the case of Li 8 SiP 4 signals at 3.3 and 11.5 ppm are observed for 7 Li (Figure 4b)a nd 29 Si (Figure 4d), respectively,w hile in Li 2 SiP 2 the 7 Li (Figure 4a)a nd 29 Si (Figure 4c)r esonances are detected at 2.1 and À14.8 ppm, respectively.T he 7 Li resonance in Li 2 SiP 2 is accompanied by as et of spinning side bands.S ince the range of the chemical shiftf or 7 Li atoms within ag iven environment (oxidic, nitridic) in the absence of paramagnetic or Knight shifts is very narrow and spans only ac ouple of ppm it is not surprising that the different Li positions (three in Li 2 SiP 2 , five in Li 8 SiP 4 )c ould not be resolved. The 7 Li and 29 Si chemical shift values compare quite well with those of related compounds such as the Li 2 SiP 2 -iso-structuralL i 2 SiN 2 (d( 7 Li) = 1.7 ppm [24b] ), Li 2 SrSi 2 N 4 (d( 7 Li) = 2.0 ppm [43] ), and SiP (d( 29 Si) = À6.0 to À34.5 ppm [44] ). The appearance of as ingle resonance in the 29 Si NMR spectra nicely agreesw ith the presence of as ingle Si position within the asymmetricu nit in both phases.I nt he case of Li 8 SiP 4 ,t he signal is split into aq uintet owing to the J-coupling to four I = 1 = 2 31 Pn uclei, which supports the existence of the SiP 4 unit in agreement with the findings from the XRD experiments( J (29Si31P) = 111 Hz; cf.…”

Nitridosilicates and Oxonitridosilicates: From Ceramic Materials to Structural and Functional Diversity

“…[84] The quaternary lithium alkaline earth nitridosilicates Li 2 MSi 2 N 4 with M = Ca, Sr form an established network structure. [85] In this case, the structure is closely related to that of BaAl 2 S 4 , BaGa 2 S 4 , and the high-pressure modifications of the borates MB 2 O 4 (M = Ca, Sr), which are reported to crystallize in Net 39. , they are used industrially in pc-LEDs as highly efficient red-to-orange emitting luminescent materials (see Section 7.5). [15,89] M 2 Si 5 N 8 with M = Sr, Ba, [90] and Eu [91] crystallize isotypically in the space group Pmn2 1 .…”

Narrow-band red-emitting Sr[LiAl3N4]:Eu2+ as a next-generation LED-phosphor material

“…The onset at 73 eV of the Al-L 2,3 edge overlaps with the Li-K edge, but the shape of the Al edges correlates with data published in the literature, the peak maximum being determined to be 85 eV, which is in good accordance with the values obtained from the literature 29 . The Li-K edge shows a slight deviation compared to the literature data; for example, Li x TiP (x = 2-11), Li 2 CaSi 2 N 4 or Li 2 SrSi 2 N 4 , due to different bonding types 30,31 . However, the EELS measurements clearly confirm the presence of Li and Al in the structure.…”