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High Na‐ion conducting Na 1+ x [Sn x Ge 2− x ( PO 4 ) 3 ] glass‐ceramic electrolytes: Structural and electrochemical impedance studies
Author(s) -
Gandi Suman,
Chinta Srinivasa Rao,
Ojha Prasanta Kumar,
Surendra Babu Manubolu Surya,
Ravuri Balaji Rao
Publication year - 2018
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15103
Subject(s) - crystallization , crystallography , germanium , ion , materials science , octahedron , crystal structure , fast ion conductor , analytical chemistry (journal) , phase (matter) , germanium oxide , quenching (fluorescence) , electrolyte , chemistry , metallurgy , silicon , physics , organic chemistry , electrode , chromatography , quantum mechanics , fluorescence
Na‐ion conducting Na 1+ x [Sn x Ge 2− x ( PO 4 ) 3 ] ( x = 0, 0.25, 0.5, and 0.75 mol%) glass samples with NASICON ‐type phase were synthesized by the melt quenching method and glass‐ceramics were formed by heat treating the precursor glasses at their crystallization temperatures. XRD traces exhibit formation of most stable crystalline phase NaGe 2 ( PO 4 ) 3 ( ICSD ‐164019) with trigonal structure. Structural illustration of sodium germanium phosphate [NaGe 2 ( PO 4 ) 3 ] displays that each germanium is surrounded by 6 oxygen atom showing octahedral symmetry (GeO 6 ) and phosphorous with 4 oxygen atoms showing tetrahedral symmetry ( PO 4 ). The highest bulk Na + ion conductivities and lowest activation energy for conduction were achieved to be 8.39 × 10 −05 S/cm and 0.52 eV for the optimum substitution levels ( x = 0.5 mol%, Na 1.5 [Sn 0.5 Ge 1.5 ( PO 4 ) 3 ]) of tetrahedral Ge 4+ ions by Sn 4+ on Na–Ge–P network. CV studies of the best conducting Na 1.5 [Sn 0.5 Ge 1.5 ( PO 4 ) 3 ] glass‐ceramic electrolyte possesses a wide electrochemical window of 6 V. The structural and EIS studies of these glass‐ceramic electrolyte samples were monitored in light of the substitution of Ge by its larger homologue Sn.