Synthesis of NASICON with New Compositions for Electrochemical Carbon Dioxide Sensors* (original) (raw)
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Carbon dioxide sensor using NASICON prepared by the sol-gel method
Sensors and Actuators B-chemical, 1995
Solid-electrolyte sensors using NASICON for detecting CO2 gas are prepared by the sol-gel method. Starting materials are the alkoxides Si(Oc;H,),, Zr(OGH&, PO(OC4H9), and NaOGH,. Because of their fine powders, the sintering temperature can be low. The phase identification is carried out by X-ray diffractometry (XRD). E.m.f. cells are constructed by fixing the NASICON disk to the end of a quartz tube with an inorganic adhesive. The devices with (Li, Ba)CO, as sensing electrode and air as reference electrode show high sensitivity to 300-5000 ppm CO2 gas and good stability for a sintering temperature of 1000 "C.
Electrical properties of sol–gel processed NASICON having new compositions
Sensors and Actuators B: Chemical, 2000
High-conductivity and high-density samples with new compositions in the NASICON-type electrolyte series, i.e., the Ž. Ž. Ž. Na Zr Si P O system, with x s 0 A , 0.667 B , and 1.333 C were synthesized using a mixed inorganic-organic sol-gel 3 2yŽ x r4. 2yx 1qx 12 process. The sinterability was improved with increasing the x value, but the conductivity decreased. Highly dense samples were obtained by sintering at 11008C. The conductivity decreased with decreasing the c lattice parameter of the hexagonal structure. Nevertheless, the CO gas sensors using the highly dense B and C samples showed good EMF response which is very close to the theoretical value.
NASICON thick film-based CO2 sensor prepared by a sol–gel method
Sensors and Actuators B: Chemical, 2001
Thick ®lms of NASICON (Na conductor, Na 3 Zr 2 Si 2 PO 12 ) were prepared for the fabrication of a planar CO 2 sensor. The powder of a precursor of NASICON, derived through a sol±gel process, was screen-printed on an alumina substrate and converted into a NASICON thick ®lm by calcination. The formation of crystalline NASICON was almost complete after calcination at 900 and 10008C, but the ®lms remained rather poor in densi®cation. On the other hand, the ®lms were densi®ed after calcination at 11008C or above, but NASICON phase disappeared by decomposition. The planar CO 2 sensor device was thus fabricated by using the NASICON thick ®lm (30 mm thick) calcined at 10008C. The device attached with a binary carbonate auxiliary phase (Li 2 CO 3 ±BaCO 3 ) showed fairly good CO 2 sensing properties at 450±6008C, despite rather poor densi®cation of the thick ®lm used. #
Development of a NASICON-based amperometric carbon dioxide sensor
Sensors and Actuators B: Chemical, 2000
Ž . An alkaline silicate sol-gel approach has been established for the preparation of NASICON sodium super ionic conductor . The prepared NASICON is characterized and used as the solid electrolyte and the base for an amperometric carbon dioxide sensor. An auxiliary electrolyte, a binary carbonate eutectic, is employed in this development. The fabrication and evaluation results of the sensor prototype are presented. Issues and future advancement of this sensor are also discussed. q
Sensors and Actuators B: Chemical, 2009
Macrostructural effects of an auxiliary electrode on the CO 2 gas sensing properties of NASICON (Na 3 Zr 2 Si 2 PO 12) solid electrolyte sensors were investigated. The sensor with a porous Li 2 CO 3-BaCO 3-based auxiliary layer (mp-Sensor), which was prepared by utilizing constituent metal acetates and polymethylmethacrylate microspheres as a template, showed faster CO 2 response and recovery and smaller cross-response against humidity changes than those obtained with a dense auxiliary layer without pores (d-Sensor). The magnitude of CO 2 response of mp-Sensor was slightly larger than the theoretical one, probably due to the existence of impurities which might have reacted with CO 2 in the auxiliary layer. On the other hand, c-Sensor with a thicker and dense auxiliary layer, which was prepared by commercially available carbonates, showed smaller CO 2 response and larger cross-response to humidity than mp-Sensor and d-Sensor. Thus, the use of the porous auxiliary layer prepared by constituent metal acetates was confirmed to be effective for improving the CO 2 sensing properties along with the large CO 2 response and small cross-response to humidity.
Sensors and Actuators B: Chemical, 1996
RF magnetron sputtered Nasicon and sodium carbonate ionic conductive thin films (2000 A) have been characterized using physical-chemical methods such as Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). It is found that the overall chemical composition of sputtered and of laser deposited films is similar to that of the sputtering target. The Nasicon films show a sufficiently high ionic conductivity (0.36 S cm -I at 360°C) for use in a prototype integrated CO 2 sensor with the dimensions of 3 x 4 mm.
Journal of Sensor Science and Technology, 2014
CO 2 sensor was used only one solid electrolyte in many cases. To improve the sensing characteristics of CO 2 sensors, solid electrolyte CO 2 sensor has been developed by bi-electrolyte type sensor using Na-Beta-alumina and YSZ. However, in many further studies, bielectrolyte type sensor was made by pellet pressed by press machine and additional treatment for formation of interface. In the aspect of mass production, using thick film and additional treatment is not suitable. In this study, CO 2 sensor was fabricated by bi-electrolyte structure which was made by an NBA paste layer deposited on YSZ pellet and fired at 1650 o C for 2 hour. The formation of stable interface between YSZ and NBA were confirmed by SEM image. When the type IV electrochemical cell arrangement represented by CO 2 ,O 2 ,Pt| Li 2 CO 3-CaCO 3 ||NBA||YSZ|O 2 ,Pt is used to measure the CO 2 concentration in air. This sensor EMF should depend only on the concentration of CO 2 by logarithmic. Also, sensor shows P CO 2 and EMF relationship like nerstian reaction at a temperature of 450 o C.
Applied Physics A Solids and Surfaces, 1993
A solid electrolyte C O 2 s e n s o r using a sodium ionic conductor and a lithium carbonate-based auxiliary phase was investigated. The sensor responded excellently to CO s in the temperature range of 350-600 ° C, without being affected by coexistent water vapor. The EMF responses to varying partial pressures of CO s (Pco2) followed a 2-electron reaction of CO 2 under fixed Po2" Under fixed Pco2(2 x 10 -3 atm), the EMF was found to be almost independent of Po at temperatures above 450 ° C, while it depended on Po~ following a 2-electron reaction of 0 2 at 305°C and below. Two alternative sensing electrode reactions were proposed to take place depending on the working temperature. 82.80, 85.80 From the global environmental issue, there is a growing need for high performance gas sensors to detect oxygenic gases such as NOx, SOx, and CO 2. Potentiometric gas sensors using solid electrolytes are of particular interest from the viewpoints of simple element structure and low cost [1-5], Solid electrolyte CO a sensor using NASICON (Na3ZraSi2PO12, a sodium ionic conductor) and Na2CO 3 (an auxiliary phase) was reported by Maruyama et al. [4]. Recently, we found that the use of a binary carbonate system, Na2CO3-MCO 3 M = Ca, Sr, or Ba), instead of Na2CO 3 could improve the CO 2 sensing characteristics of this type of device 7]. It was further found that the use of a Li carbonate-based binary system, Li2CO3-MCO3 M = Ca, Sr, or Ba), could give even better CO 2 sensing properties as well as better physical stability under an extremely humid condition at room temperature . Despite excellent CO 2 sensing properties, however, the sensing mechanism of these devices has not been understood well yet. In this paper, CO s sensing performance of the sensor device fitted with Li2CO3-BaCO 3 was investigated under various conditions in order to collect information regarding the sensing mechanism.
Journal of Solid State Chemistry, 2004
In this work, we present the synthesis and the characterization of ionic conducting ceramics of NaSICON-type (Natrium super ionic conductor). The properties of this ceramic make it suitable for use in electrochemical devices. These solid electrolytes can be used as sensors for application in the manufacturing of potentiometric gas sensors, for the detection of pollutant emissions and for environment control. The family of NaSICON that we studied has as a general formula Na 2.8 Zr 2Ày Si 1.8À4y P 1.2+4y O 12 with 0pyp0.45. The various compositions were synthesized by produced using the sol-gel method. The electric properties of these compositions were carried out by impedance spectroscopy. The results highlight the good conductivity of the Na 2.8 Zr 1.775 Si 0.9 P 2.1 O 12 composition. r 2004 Elsevier Inc. All rights reserved.
Ionics, 2002
Tin oxide is a well-known and widely used gas sensitive material for detection of toxic and hazardous gas components in air. Different admixtures such as catalysts, aliovalent ions and solid ionic conductors were ~ to improve the sensitivity, selectivity and stability of these sensors. For material preparation a sol-gel route is usually used and catalysts are added before sintering to improve the sensitivity and to favour the sensors to specific gas components.