Comprehensive Investigation of Anion Species in Crystalline Li⁺ ion Conductor Li_27−x[P₄O_7+xN_9−x]O₃ (x≈1.9(3))

Abstract

The Li + ion conductor Li 27 À x [P 4 O 7 + x N 9 À x ]O 3 (x � 1.9) has been synthesized from P 3 N 5 , Li 3 N and Li 2 O in a Ta ampoule at 800 °C under Ar atmosphere. The cubic compound crystallizes in space group I43d with a = 12.0106(14) Å and Z = 4. It contains both non-condensed [PO 2 N 2 ] 5À and [PO 3 N] 4À tetrahedra as well as O 2À ions, surrounded by Li + ions. Charge neutrality is achieved by partial occupancy of Li positions, which was refined with neutron powder diffraction data. Measurements of the partial ionic and electronic conductivity show a total ionic conductivity of 6.6 × 10 À 8 S cm À 1 with an activation energy of 0.46 � 0.02 eV and a bulk ionic conductivity of 4 × 10 À 6 S cm À 1 at 25 °C, which is close to the ionic conductivity of amorphous lithium nitridophosphate. This makes Li 27 À x [P 4 O 7 + x N 9 À x ]O 3 an interesting candidate for investigation of structural factors affecting ionic conductivity in lithium oxonitridophosphates.x N 1 + x with pairs of corner-sharing tetrahedra [P 2 O 6 N] 5À with a bridging N atom has been reported. [21] Crystalline lithium [a] S.

Finding Order in Disorder: The Highly Disordered Lithium Oxonitridophosphate Double Salt Li8+xP3O10−xN1+x (x=1.4(5))

“…Thus, one third of the total area of the signals must result from non‐condensed tetrahedra, whereas two thirds result from double‐tetrahedra. The chemical shift of non‐condensed P(O,N) 4 tetrahedra is well investigated and increases by about 10 ppm for each O that is substituted by N [13,19,20,22,39] . The signal at δ iso =33.7 ppm can be assigned to [PO 2 N 2 ] 5− , which is in good accordance with literature data (31.3 and 33.0 ppm) [20,22] .…”

“…The ionic conductivity of Li 8 + x P 3 O 10 À x N 1 + x is comparable to that of other known lithium oxonitridophosphates, which range from 1×10 À 13 S cm À 1 (Li 2.88 PO 3.73 N 0.14 ) to 1.6×10 À 6 S cm À 1 (amorphous LiPON) at room temperature. [17,18,[20][21][22]46] Conclusions With Li 8 + x P 3 O 10 À x N 1 + x , a new crystalline lithium oxonitridophosphate was synthesized from ampoule synthesis. It is a double salt containing both phosphate and diphosphate motifs.…”

“…[20,22] The signal at 16. agreement with [P 2 O 6 N] 5À motifs in literature (14.6 and 14.2 ppm). [13,21] The signal resulting in a shoulder with a chemical shift of 21.8 ppm can be attributed either to [PO 3 N] 4À (19.4, 19.8, and 19.6 ppm in literature) [13,20,22] or to [P 2 O 5 N 2 ] 6À (21.4 ppm in literature). [21] results.…”

“…Impedance spectroscopy showed a total Li + conductivity of 1.2×10 À 7 S cm À 1 at 25 °C, with a total activation energy of 0.47(2) eV, which is within the range of other crystalline lithium oxonitridophosphates. [17,18,[20][21][22]46] The significant disorder in the structure might be beneficial for the system's conductivity. Density functional theory (DFT) calculations could be employed to give further insights to the mechanisms of conductivity in lithium oxonitridophosphates in general and in Li 8 + x P 3 O 10 À x N 1 + x specifically.…”

Zeolite-like Topology Oxonitridosilicate La3.6Ba1.7Si5N10O2.1 with Potential Applications in Nonlinear Optical Materials

“…Almost all of the natural silicates are oxosilicates, except for Si 2 N 2 O, which is the only naturally oxonitridosilicate mineral found in meteorites . Over the years, (oxo)­nitridosilicates have been extensively synthesized and have emerged as a promising class of compounds due to their intriguing material properties, e.g., lithium-ion conductivity, , rare earth doped luminescence, − and nonlinear optical (NLO) materials. , These various types of properties originate from their broad structural diversity. From a chemical perspective, when oxygen atoms are substituted by nitrogen in oxosilicates, the basic building blocks transform from oxides to nitrides. , Undoubtedly, this substitution notably broadens the range of possible structural configurations and expands the variety of traditional silicate chemistry .…”