scholarly journals In-Situ Temperature Measurement on CMOS Integrated Micro-Hotplates for Gas Sensing Devices

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 672 ◽  
Author(s):  
Marco Deluca ◽  
Robert Wimmer-Teubenbacher ◽  
Lisa Mitterhuber ◽  
Johanna Mader ◽  
Karl Rohracher ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Metal Oxide ◽  
Joule Heating ◽  
Gas Sensors ◽  
Elevated Temperatures ◽  
Smart Devices ◽  
Cmos Process ◽  
In Operando ◽  
Spatial Temperature

Metal oxide gas sensors generally need to be operated at elevated temperatures, up to and above 400 °C. Following the need for miniaturization of gas sensors and implementation into smart devices such as smartphones or wireless sensor nodes, recently complementary metal-oxide-semiconductor (CMOS) process-based micro electromechanical system (MEMS) platforms (micro-hotplates, µhps) have been developed to provide Joule heating of metal oxide sensing structures on the microscale. Heating precision and possible spatial temperature distributions over the µhp are key issues potentially affecting the performance of the overall gas sensor device. In this work, we use Raman spectroscopy to directly (in-situ and in-operando) measure the temperature of CMOS-based µhps during the application of electric current for Joule heating. By monitoring the position of the Raman mode of silicon and applying the theoretical framework of anharmonic phonon softening, we demonstrate that state-of-the-art µhps are able to reach the set temperature with an error below 10%, albeit with significant spatial temperature variations on the hotplate. This work demonstrates the potential of Raman spectroscopy for in-situ and in-operando temperature measurements on Si-based devices, an aspect of high relevance for micro- and nano-electronic device producers, opening new possibilities in process and device control.

scholarly journals Application of Raman Spectroscopy to Working Gas Sensors: From in situ to operando Studies

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5075 ◽  
Author(s):  
Elger ◽  
Hess
Keyword(s):  
Raman Spectroscopy ◽  
Metal Oxide ◽  
Gas Sensors ◽  
Molecular Level ◽  
Knowledge Based ◽  
Mode Of Operation ◽  
Metal Oxide Gas Sensors ◽  
Operando Studies

Understanding the mode of operation of gas sensors is of great scientific and economic interest. A knowledge-based approach requires the development and application of spectroscopic tools to monitor the relevant surface and bulk processes under working conditions (operando approach). In this review we trace the development of vibrational Raman spectroscopy applied to metal-oxide gas sensors, starting from initial applications to very recent operando spectroscopic approaches. We highlight the potential of Raman spectroscopy for molecular-level characterization of metal-oxide gas sensors to reveal important mechanistic information, as well as its versatility regarding the design of in situ/operando cells and the combination with other techniques. We conclude with an outlook on potential future developments.

Oxide Scale Formation on Iron-Chromium Alloys in Elevated Temperature Air Environments

CORROSION ◽  
1981 ◽  
Vol 37 (12) ◽  
pp. 700-711 ◽  
Author(s):  
P. Fabis ◽  
R. Heidersbach ◽  
C. Brown ◽  
T. Rockett
Keyword(s):  
Raman Spectroscopy ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Experimental Program ◽  
Oxide Scales ◽  
Chromium Alloys ◽  
Spectroscopy Instrumentation ◽  
Commercial Iron ◽  
Iron Chromium

Abstract Oxide scales formed on metals at elevated temperatures may be different, both chemically and structurally, from the scales on the metal once it has cooled to room temperature. This paper discusses Raman spectroscopy instrumentation for the in-situ identification of scales formed on metal surfaces exposed to gaseous environments. The results of an experimental program to characterize scales formed on two commercial iron-chromium alloys, AISI 446 and 502, in air and oxygen environments are also presented.

Metal-Support Interactions and C1 Chemistry: Transforming Pt-CeO2 into a Highly Active and Stable Catalyst for the Conversion of Carbon Dioxide and Methane

2020 ◽  
Author(s):  
Feng Zhang ◽  
Ramón A. Gutiérrez ◽  
Pablo Lustemberg ◽  
Zongyuan Liu ◽  
Ning Rui ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Metal Oxide ◽  
Elevated Temperatures ◽  
Chemical Properties ◽  
Oxide Interface ◽  
Highly Active ◽  
Metal Support ◽  
Metal Support Interactions ◽  
Methane Dissociation

There is an ongoing search for materials which can accomplish the activation of two dangerous greenhouse gases like carbon dioxide and methane. In the area of C1 chemistry, the reaction between CO2 and CH4 to produce syngas, known as methane dry reforming (MDR), is attracting a lot of interest due to its green nature. On Pt(111), elevated temperatures are necessary to activate the reactants and massive deposition of carbon makes this metal surface ineffective for the MDR process. In this study, we show that strong metal-support interactions present in Pt/CeO2(111) and Pt/CeO2 powders lead to systems which can bind well CO2 and CH4 at room temperature and are excellent and stable catalysts for the MDR process at moderate temperature (500 ºC). The behaviour of these systems was studied using a combination of in-situ/operando methods which pointed to an active Pt-CeO2-x interface. In this interface, the oxide is far from being a passive spectator. It modifies the chemical properties of Pt, facilitating improved methane dissociation, and is directly involved in the adsorption and dissociation of CO2 making the MDR catalytic cycle possible. A comparison of the benefits gained by the use of an effective metal-oxide interface and those obtained by plain bimetallic bonding indicates that the former is much more important when optimizing the C1 chemistry associated with CO2 and CH4 conversion. The presence of elements with a different chemical nature at the metal-oxide interface opens the possibility for truly cooperative interactions in the activation of C-O and C-H bonds.

scholarly journals Metal-Support Interactions and C1 Chemistry: Transforming Pt-CeO2 into a Highly Active and Stable Catalyst for the Conversion of Carbon Dioxide and Methane

2020 ◽  
Author(s):  
Feng Zhang ◽  
Ramón A. Gutiérrez ◽  
Pablo Lustemberg ◽  
Zongyuan Liu ◽  
Ning Rui ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Metal Oxide ◽  
Elevated Temperatures ◽  
Chemical Properties ◽  
Oxide Interface ◽  
Highly Active ◽  
Metal Support ◽  
Metal Support Interactions ◽  
Methane Dissociation

There is an ongoing search for materials which can accomplish the activation of two dangerous greenhouse gases like carbon dioxide and methane. In the area of C1 chemistry, the reaction between CO2 and CH4 to produce syngas, known as methane dry reforming (MDR), is attracting a lot of interest due to its green nature. On Pt(111), elevated temperatures are necessary to activate the reactants and massive deposition of carbon makes this metal surface ineffective for the MDR process. In this study, we show that strong metal-support interactions present in Pt/CeO2(111) and Pt/CeO2 powders lead to systems which can bind well CO2 and CH4 at room temperature and are excellent and stable catalysts for the MDR process at moderate temperature (500 ºC). The behaviour of these systems was studied using a combination of in-situ/operando methods which pointed to an active Pt-CeO2-x interface. In this interface, the oxide is far from being a passive spectator. It modifies the chemical properties of Pt, facilitating improved methane dissociation, and is directly involved in the adsorption and dissociation of CO2 making the MDR catalytic cycle possible. A comparison of the benefits gained by the use of an effective metal-oxide interface and those obtained by plain bimetallic bonding indicates that the former is much more important when optimizing the C1 chemistry associated with CO2 and CH4 conversion. The presence of elements with a different chemical nature at the metal-oxide interface opens the possibility for truly cooperative interactions in the activation of C-O and C-H bonds.

In situ synthesis of porous array films on a filament induced micro-gap electrode pair and their use as resistance-type gas sensors with enhanced performances

Nanoscale ◽  
2015 ◽  
Vol 7 (34) ◽  
pp. 14264-14271 ◽  
Author(s):  
Zongke Xu ◽  
Guotao Duan ◽  
Hongwen Zhang ◽  
Yingying Wang ◽  
Lei Xu ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Model Material ◽  
In Situ Synthesis ◽  
Electrode Pair ◽  
Porous Array

In this paper, a new gas sensor of metal-oxide porous array films on a micro-gap electrode pair is designed and implemented by taking ZnO as a model material.

scholarly journals In Situ Raman Spectroscopy as a Tool for Discerning Subtle Structural Differences between Commercial (Ce,Zr)O2-Based OSC Materials of Identical Composition

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 462
Author(s):  
Chrysanthi Andriopoulou ◽  
Deb Harris ◽  
Hazel Stephenson ◽  
Angelos M. Efstathiou ◽  
Soghomon Boghosian
Keyword(s):  
Raman Spectroscopy ◽  
Metal Oxide ◽  
Raman Spectra ◽  
Mixed Metal Oxide ◽  
Oxide Materials ◽  
In Situ Raman Spectroscopy ◽  
Aqueous Chemistry ◽  
Mixed Metal ◽  
In Situ Raman

In situ Raman spectroscopy was used at temperatures in the 50–480 °C range under oxidizing (20% O2/He) and reducing (5% H2/He) flowing gas atmospheres to compare the spectra obtained for a series of industrial rare earth doped CexZr1−xO2−δ oxygen storage capacity (OSC) mixed metal oxide materials of identical at % composition, which were prepared by the same chemical synthesis route, in which one synthesis parameter of the aqueous chemistry was slightly varied. The Raman fingerprint of the anionic sublattice is very sensitive to O atom relocations within the bulk of the material matrix and to the pertinent defect topology in each case. A protocol of sequential Raman measurements and analysis was proposed to discern subtle differences between the oxygen vacancy and defect topologies of the examined materials. It can be concluded that for two materials under comparison for their structures, identical Raman spectra are obtained only if the procedures followed for their preparation are identical; a slight variation of one single parameter (e.g., in the aqueous chemistry stage) results in discernible differences in the Raman spectra. The proposed procedure can serve as a tool for proving or disproving infringement of IPR (Intellectual Property Rights) protected preparation methods of ceria-based mixed metal oxide materials.

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