Sputter-deposited network glasses

Abstract

Thin films of lithium borate, sodium borate, rubidium borate, and lithium silicate glasses are prepared by ion beam sputter deposition in a thickness range between 70 and 1,400 nm. The chemical, structural, and electrical properties of the films are determined by transmission electron microscopy and impedance spectroscopy. A comparison between the thin glass layers and the corresponding bulk glasses, prepared from the melt, shows that both have similar chemical compositions and atomic short range orders. In contrast, the ionic conductivities of the borate glass films are found to be significantly increased compared to the corresponding bulk materials, while the increase depends on the chemical composition of the glasses and is not observed in the case of the silicate system. We propose a modified network structure of the sputterdeposited glass layers, namely, an increased nonbridging oxygen concentration, to be responsible for the elevated ionic conductivity.

Finite Size Effect of Proton-Conductivity of Amorphous Silicate Thin Films Based on Mesoscopic Fluctuation of Glass Network

“…Consequently, the Li ion conductivity across the a-Li-B-O thin film may continuously increase until the thickness decreases down to <10 nm. Recently, this phenomemon of ion conducting a-Li-B-O thin films was experimentally substantiated by Berkemeier et al 15,16 Such a model on the basis of the site-to-site defect motion does not match to our case. The λ of a silicate film is clearly larger than the ionic jump distance by 1 or 2 orders of magnitude.…”

“…In more recent years, it was reported that the conductivity of some ionic glass films is dramatically enhanced by reducing thickness into the mesoscopic region. [15][16][17][18] The relatively high ion-conducting pathways can be locally formed inside a glass matrix because its heterogeneous structure provides distributed potential for ionic diffusion in various lengths. 19 When the thickness of glass bulk decreases to the range of the mean length of the ion-conducting pathways, the pathway percolating from edge to edge is formed, and thus the overall conductivity across film must be increased.…”

“…The development of artificial solid electrolytes that possess high ionic conductivity at relatively low temperatures is of great challenge for materials chemists, since it is essential to increase efficiency and lifetime of the solid-state electrochemical devices such as a solid-state fuel cell, , all-solid-state battery, , membrane reactor, memristic switch, , and so on. Recently, more and more evidence of the importance of nanoscale structure in relation to ionic conductivity has been compiled, − not only where strong variations in the conductivities are achieved but also where qualitative effects such as changing the type of conductivity could be observed. In more recent years, it was reported that the conductivity of some ionic glass films is dramatically enhanced by reducing thickness into the mesoscopic region. − The relatively high ion-conducting pathways can be locally formed inside a glass matrix because its heterogeneous structure provides distributed potential for ionic diffusion in various lengths .…”

Ceramic and polymeric solid electrolytes for lithium-ion batteries

“…8 [61][62][63][64][65][66]. The conductivities of a Li 3 BO 2.5 N 0.5 thin-film glass and of Li 9 SiAlO 8 , which is a derivative of Li 4 SiO 4 , are close to the conductivity range of LLTO.…”

Percolative proton conductivity of sol–gel derived amorphous aluminosilicate thin films

“…In more recent years, several research groups have reported on the emerging size enhancement of ionic transport across the very thin glassy layer, where the conductivity across the film exponentially increases with decreasing thickness in the nanometre range. [10][11][12][13][14][15] This finite-size effect must be related to the existence of a percolative ionic channel penetrating through the glass matrix. The relatively high ion-conducting pathways can be accumulated in the glass network because the heterogeneous nanostructures of glass provide a distributed potential for ionic diffusion in the nanometre length scale.…”