NASICON solid electrolytes

Nasicon solid electrolyte electrochemical promotion with, 440 sodium ion conductor, 440 NEMCA, see electrochemical promotion NEMCA coefficient, 152,319... 

A similar device with Nasicon solid electrolyte Na3Sc(P04)3 is used when analyzing the concentration of nitrogen oxides in air. The electrochemical system in this sensor can be formnlated as... 

Upon discharge sodium ions diffuse through the sodium-conducting /J- or -alumina or NASICON -> solid electrolyte. On the outer surface of the solid electrolyte they react with molten sulfur and/or low valency sulfide anions forming negatively charged polysulfide anions. The rather low electric conductivity of molten sulfur is improved by addition of tetracyanoethylene... 

Zhou, M. and Ahmad, A. (2007) Synthesis, processing and characterization of nasicon solid electrolytes for CO2 sensing applications. Sens. Actuators B, 122 (2), 419—26. 

In Type III, there is an auxiliary phase attached on the surface of the solid electrolyte so as to be sensitive to the gas, and it is produced by a compound that contains the same ionic species as derived from the gas. The auxiliary phase can act as a sort of poor ion-conducting solid electrolyte, which forms a half cell of Type I or II as shown in Figure 1.1 [1]. Type III sensors can be divided into three subgroups depending on the types of the half cells combined [6]. Since a NASICON solid electrolyte potentiometric gas sensor using alkali metal carbonate as an auxiliary phase solid electrolyte is known to be sensitive to CO2, Type III sensors have been of immense importance as sensors for oxygenic gases such as CO2, NOx, and SOx... 

Fig. 15.4. Plot of log Ph2 versus EMF of an electrochemical cell with a NASICON solid electrolyte and Pt electrodes. The slope of the line indicates near Nernstian behaviour (r=25 2°C).

Potentiometric hydrogen sensors designed using a NASICON solid electrolyte similarly exhibited a strong RH effect, and this makes it difficult to work in a dry atmosphere (Chehab et al. 1991). 

H. Kohler, H. Schulz Nasicon Solid Electrolytes - Part I The Na+-diffusion path and its relation to the structure. Mater. Res. Bull. 20 (1985) 1461. The figure is reprinted from this reference. Copyright 1985, with permission from Elsevier. 

Instead of the system silica/silicate also other systems such as titania/titanate, zirconia/zirconate can be used as a reference system [xiv]. The response time of freshly fabricated thick-film sensors based on thin-film /3-alumina is very short (about 15 ms at 650 °C). After several weeks of operating this time increases 10 times (150 ms) [xv]. Solid electrolyte C02 sensors using Ni/carbonate composite as measuring electrode are suited for measuring of C02 in equilibrated water gases [xiv]. Using semiconducting oxides and carbonates like ITO (indium tin oxide) Nasicon-based C02 sensors are able to measure at room temperature [xvi]. 

Crystalline solid electrolytes such as a-Agl, ji-alumina, NASICON, and LISICON, LLN, oxide ion conductors such as yttria-stabilized zirconia, etc ... 

Forsyth, M., Wong, S., Nairn, K., Best, A., Newman, P., and MacFarlane, D., NMR studies of modified NASICON-like, lithium conducting solid electrolytes. Solid State Ionics, 124, 213, 1999. 

Zhu, Q., Qiu. F., Quan, Y., Sun, Y.. Liu. S. and Zou, Z. (2005) Solid-electrolyte NASICON thick film CO2 sensor prepared on small-volume ceramic tube substrate. Mater. Chem. Phys., 91 (2-3), 338-42. 

Bhoga. S.S. and Singh. K. (2005) Performance of electr ochemical CO2 gas sensor with NASICON dispersed in a binar y solid electrolyte system. Indian J. Phys.. 79 (7). 725-6. 

Yao, S., Hosohara, S.. Shimizu. Y. Miura. N., Futata, H. and Yamazoe, N. (1991) Solid electrolyte CO2 sensor using NASICON and Li-based binary carbonate electrode. Chem. l tt., 2069—72. 

A sodium-ion conductor (Nasicon) is used as the solid electrolyte. Various oxides have been proposed for the auxiliary phase, depending on the target test gas, includ-... 

Figure 12. CO2 sensor using BaC0a-Na2C03 as auxiliary electrode and NASICON as solid electrolyte[59,60].

Alkali metal sulfates [11,12], Ag-(5 -alumina [13], Na-fJ-alumina [14], NASICON (NajZrjSijPOj,) [15], MgO-stabilized [16,17], sulfate-based solid electrolytes [15]... 

FIGURE 1.1 Three types of solid electrolyte gas sensors (AP Auxiliary phase, Type III for CO2 sensor using NASICON/NajCOj). (Reprinted from IEEE Sensors J., 1, Lee D.-D et ah. Environmental gas sensors, 2001, with permission from Elsevier.)... 

Saito Y, Mamyamn T., and Sasaki S., Gas Sensors Using NASICON as a Solid Electrolyte, Report of the Research Laboratory of Engineering Materials, Tokyo Instimte of Technology, 1984. 

Shimizn Y. and Yamashita N., Solid electrolyte COj sensor nsing NASICON and per-ovskite-type oxide electrode. Sens. Actuators B, 64, 102-106, 2000. 

It is evident from our discussion that very little work has been carried out on the proton phases of NASICON. However, with the background given here it should be apparent that such phases are extremely interesting as solid electrolytes and deserve further study. 

One of the typical examples is NASCION compound (Fig. 9.1), an acronym for A/d mper /on conductor. Before attracting interest as a cathode-active material, NASICON has a long research history of over 20 years as a solid electrolyte. Since Dehnas reported - that while LiTi2(PO )3 works as a lithium intercalation host and NaTi3(PO )3 works as a Na intercalation host, many attractive cathodes have been proposed based on the NASICON material group. 

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