1. Adelina Stănoiu (former Tomescu), U-1700-038M-8092
2. Cristian Eugen Simion, U-1700-030F-9765
3. Corneliu Ghica, U-1700-029U-5827
4. Ioana Dorina Vlaicu, U-1700-037A-2366
5. Andrei Cristian Kuncser, U-1700-032N-6988
6. Cătălina Gabriela Mihalcea, U-1900-062F-0766
7. Ionel Florinel Mercioniu, U-1700-039E-8823
8. Daniela Ghica, U-1700-035Y-0481
9. Mariana Ștefan, U-1700-034N-5930
10. Ion Viorel Dinu, U-1700-030A-3912
11. Ovidiu Gabriel Florea, U-1700-032D-4435

Stage 1/2022 – Quantitative and qualitative Gd doping level effects.
In the case of chemo-resistive gas sensors, the main requirements are related to sensitivity and selectivity, along with a good stability over time of the material parameters. Therefore, at this stage we proceeded to a material selection based on the synthesis route, the exhaustive morpho-structural evaluations and the preliminary sensing investigations.
Activity 1.1. Synthesis of nanostructured powders: SnO₂, Gd₂O_3, and SnO₂ doped with 1-20 at. % Gd.
A premise of any fundamental study or any commercial application is the reproducibility and control of each step in the technological process. Therefore, the optimization of the material synthesis in accordance with the experiment and the final application, was taken into consideration at this stage. Pure and Gd-doped SnO2 powders, with the general formula Sn1-xGdxO(4-x)/2 (where x = 0.01; 0.05; 0.1; 0.2, corresponding to nominal concentrations of 1, 5, 10, 20 at. %) , and of Gd2O3 were synthesized by two alternative methods, co-precipitation and hydrothermal.
Activity 1.2. Studies on the morphology, grain size, crystal structure, crystallinity phase purity as well as pore structure by microstructural investigations of the obtained nanopowders: SnO₂, Gd₂O_3, and SnO₂ doped with 1-20 at. % Gd.
X-ray diffraction (XRD) was performed with a Bruker D8 Advance X-ray diffractometer. The Rietveld analysis indicates the formation of a SnO2 - Gd2O3 nanocomposite even for the SnO2 sample doped with 5%, considering the presence of Gd2O3 as a secondary phase with poor crystallization. TEM/HRTEM analytical results were obtained with JEOL JEM-2100 and JEOL ARM 200F transmission electron microscopes, equipped with X-ray detectors used for EDS type investigations. The results of the distribution of nanoparticles, the electron diffractogram and the HRTEM images obtained at different magnifications reveal the shape of the nanoparticles, the uniformity of the crystallite sizes and highlight the crystallographic planes. The STEM-EDS maps highlight the presence and distribution of the constituent elements, confirm the presence of Gd in the sample and the uniformity of its distribution. The two morphologies of nanoparticles, quasi-spheres and sticks, provide distinct EDS signals corresponding to tetragonal SnO2 and cubic Gd2O3. The average specific surface areas for the pure SnO2 systems and for the SnO2 systems doped with 1%, 3%, 5%, 10%, 20%Gd were estimated theoretically using the size distributions obtained by TEM. The textural properties were determined with the BET method (Brunauer, Emmett, Teller), using the Micromeritics ASAP 2020 instrument, by measuring the amount of gas (N2) adsorbed/desorbed from the surface of the powders in order to determine the specific surface area and porosity of the materials indicated by TEM/HRTEM as being porous. Electron spin resonance (RES) measurements were made in the X (9.87 GHz) and Q (34.16 GHz) microwave frequency bands. The RES spectra of all measured samples present signals characteristic of Gd3+ ions located in isolated positions in the network and respectively agglomerated. The CO2 detection properties for the sensors obtained based on the studied materials were evaluated under dynamic conditions similar to those in the field. The preliminary selection highlights the hydrothermally prepared Gd2O3 whose nano-sticks present a strong diffraction contrast typical of single-crystal micro-objects, in contrast to the mild contrast of the weakly crystallized Gd2O3 nano-sticks obtained by coprecipitation.

Stage 2/2023 –Reaction path for the interaction with CO₂ under real operating conditions.
At this stage, we set out to analyze the reaction path for the interaction with CO₂ in real operating conditions. The study allows us to see how the detection performance of Sn_1-xGd_xO_(4-x)/2 is influenced by operating temperature, relative air humidity and CO₂ concentration.
A premise of any fundamental study or any commercial application is the technology of making samples, respectively the reproducibility and control of each step in the technological process.
Thus,

• pure SnO₂ powders doped with Gd, with the general formula Sn_1-xGd_xO_(4-x)/2 (where x = 0.01; 0.05; 0.1; 0.2, corresponding to nominal concentrations of 1, 5, 10, 20 at. %), and of Gd₂O₃ were obtained by two alternative synthesis methods: co-precipitation and hydrothermal, as described in Stage 1/2022;
• the obtained powders were transformed into a paste with controlled viscosity by mixing with an organic solvent and deposited by screen-printing in the form of a thick and porous layer on commercial alumina substrates;
• the obtained sensors were evaluated in dynamic conditions similar to those in the field, ensured by a Gas Mixing System fully controlled by the computer, as described in Stage 1/2022.

Activity 2.1. Thick film layer deposition.
The sensitive layers of Sn_1-xGd_xO_(4-x)/2 used as material for CO₂ sensors were prepared in such a way that the share of surface phenomena in the global resistance of the layer was as high as possible, respectively thick and porous layers. The surface, defined as the interface between the volume of the metal oxide semiconductor (MOS) and the ambient atmosphere, plays an important role in the whole class of phenomena for which the interaction between the MOS and the environment is important.
The substrate
For simple operation and exploitation of the sensitive potential of MOS, the geometry of the substrate and the mode of operation were considered. The substrates used to make the sensors are marketed by CeramTec Germany, are made of alumina (Al₂O₃) in planar technology and are equipped with electrodes and a platinum (Pt) heater. The electrode technology determines the mode of operation. In our case, the interdigital Pt electrodes over which the MOS layer is deposited favour the measurement of electrical resistance variations of MOS, a physical parameter sensitive to chemical interactions with gases in the ambient atmosphere. The Pt heater allows modulating the temperature of the MOS layer in order to determine the optimal detection and selectivity, by favoring a certain chemical interaction.
Screen-printing deposition of the MOS layer on the Al₂O₃ substrate – obtaining the sensors
The materials prepared in the form of powders were mixed in equal proportions with 1,2 Propanediol and mortared for 15 minutes in order to obtain a medium viscosity paste, which is transferred onto commercial Al₂O₃ substrates, by the screen-printing method. The obtained sensors are slowly dried at room temperature, then in an oven at 60°C and calcined in an oven, in air flow, gradually increasing the temperature up to 500°C for the complete removal of the organic solvent and achieving the adhesion of the layer to the substrate.
Optical inspection and sensor selection depending on the uniformity of the sensitive layers.
After deposition and heat treatment, the sensitive layers are checked with the Olympus MX50 optical microscope, which allows the selection of those with superior uniformity, without cracks or agglomerations.
Heater calibration
For precise thermal control, the Pt meander-type heater deposited on the planar Al₂O₃ substrate was coated with heat-resistant black paint (up to 800°C) with the known emissivity (ε=0.95). Then, the heater was calibrated with the Lumasense IN-5L Plus optical pyrometer with adjustable emissivity, applying voltage and simultaneously measuring the current through the heater and the temperature of the paint layer. By this procedure, the high-precision calibration curve T(°C) = fP(W) of the heater is obtained.

Activity 2.2. Electrical investigations for preliminary selection with respect to the sensing properties under real operating conditions.
The sensing properties are:
The sensor signal S measures the impact of the stimulus on the sensor response. The higher the value of S, the more significant the change caused by a certain stimulus, so S can be used to evaluate the detection potential of a certain stimulus.
Selectivity (m_ij). Sensors are generally sensitive to several stimuli and for this reason, lack selectivity. Selectivity is therefore a useful measure for evaluating the specificity of the sensor by comparing the effects of various gases on the sensor. The mij selectivity of a sensor allows comparison of the sensor signal to a monitored gas with the sensor signal to another interfering stimulus.
Long-term stability (ζ) of the sensor signal. Besides the ability to sense a stimulus quickly and with high precision, a sensor is also evaluated from the point of view of its stability (time stability of the evaluated parameter) and its reproducibility. In the case of chemical sensors, due to prolonged and repeated heating-cooling cycles and exposure to moisture and various gases, it is well-known and generally accepted that the base resistance (in air) and sensor signal for MOS material varies with time.
Response and recovery time. These two measurements are usually used to measure the "speed" of the sensor. Response time (t_response) measures the minimum time required to measure a stimulus. In general, the transient response time is defined as t_90%, i.e. the time required to reach 90% of the equilibrium value of the sensor response in the presence of the stimulus. The recovery time (t_recovery) represents the time required for the sensor's response to reach the base resistance value, after the removal of the stimulus.
Real operating conditions
The CO₂ detection properties for the sensors obtained based on the studied materials were evaluated under dynamic conditions similar to those in the field (atmospheric pressure, variable relative humidity depending on the climatological conditions, variable temperature, and variable concentration of gases). Field conditions were simulated in the laboratory using the fully computer-controlled Gas Mixing System (SMG). In the temperature range in which the evaluation of the sensing properties of Sn_1-xGd_xO_(4-x)/2 was carried out, water vapour from the ambient atmosphere (%RH) acts as a potentially interfering reducing gas with CO₂. Therefore, we analyzed the influence of %RH on the sensor signal of Sn_1-xGd_xO_(4-x)/2 at the optimal operating temperature and progressive CO₂ concentration. The applicative potential was evaluated based on the relationship between the operating temperature and the electrical power consumed.

Stage 3/2024 – Charge transfer mechanisms associated to surface reactions and their link to the transduction changes determined by the macroscopic parameters.

At this stage, we aimed to analyse the charge transfer mechanisms associated with surface reactions for sensors based on Sn_1-xGd_xO_(4-x)/2 and their connection with transduction changes determined by macroscopic parameters. The study is based on the experimental results obtained through complex experimental characterisations of the sensitive properties, made by interconnecting several devices: Gas Mixing System, Sensor Chamber, Kelvin McAllister Probe, INNOVA 1314 Photoacoustic Gas Analyzer, Keithley Electrometer, and computer. The study allows the differentiation between the physisorption processes mediated by humidity and the chemisorption processes involved in the interaction with CO₂. Thus, we can identify the physico-chemical interaction model of Sn_1-xGd_xO_(4-x)/2 with CO₂ and the relationship between the sensor's extrinsic parameters and the sensitive material's intrinsic properties.

Activity 3.1. – Gas-interaction physical-chemical model based on simultaneous DC electrical resistance and work function measurements assisted by catalytic conversion.

The sensitive layers of Sn_1-xGd_xO_(4-x)/2 used as materials for CO₂ sensors were prepared in such a way that the role of surface phenomena in the global resistance of the layer is as high as possible, respectively thick and porous layers. In short, the sensors consist of a thick layer of Sn_1-xGd_xO_(4-x)/2 as a sensitive element, deposited on a commercial Al₂O₃ substrate equipped with ohmic interdigital electrodes and a meander type heater, made of Platinum. The electrodes allow the monitoring of the electrical resistance variations of the Sn_1-xGd_xO_(4-x)/2 layers during exposure to CO₂ and the heater allows the adjustment of the operating temperature by applying a constant voltage to its terminals. Exposure to variable concentrations of CO₂ (400 - 3000 ppm) for in-field conditions simulated in the laboratory, respectively synthetic air flow 5.0 (10–200 ml/min) with controlled relative humidity (0–90%RH) was facilitated by the use of the Gas Mixing System. The electrical resistance variations of the Sn_1-xGd_xO_(4-x)/2 layers were measured with the Keithley 6517A Electrometer. Material property investigations were carried out with the McAllister KP 6500 Kelvin Probe, a device for non-contact, non-destructive measurements. The operation of the Kelvin Probe is based on the principle of the vibrating capacitor and allows the measurement of the surface potential difference (CPD) between the layer of Sn_1-xGd_xO_(4-x)/2 and the vibrating tip of the Probe. This is an extremely sensitive indicator of the surface condition and is affected by surface adsorption/desorption processes, surface reconstructions, surface charge, oxide layer imperfections, and surface contamination. Under the conditions in which the dielectric (test gas atmosphere) is changed with the help of the Gas Mixing Station, the contact potential between the layer of Sn_1-xGd_xO_(4-x)/2 and the probe head (capacitor plates) also changes.

The work function contains 3 contributions: the electrochemical potential (the energy difference between the Fermi level and the bulk conduction band (E_cb-E_f)), the qV_S band-bending at the Sn_1-xGd_xO_(4-x)/2 surface and the electronic affinity. Considering constant the electrochemical potential, the two contributions that can be modified allow the decoupling of the ionosorption phenomena from those dipolar induced by the humidity. The experimental setup does not allow an evaluation of the absolute work function of the semiconductor, but only relative changes, the initial situation corresponding to the reference atmospheric conditions (synthetic air 5.0) and the final situation corresponding to the air contaminated with the test gas, RH and CO₂. The simultaneous experimental evaluation of surface potential and electrical resistance variations allows the calculation of relative electronic affinity variations.

Catalytic conversion measurements were performed by connecting before and after the sensor chamber the INNOVA 1314 Photoacoustic Gas Analyzer and alternatively the Bruker VERTEX 70v Fourier Transform Infrared Spectrometer equipped with a narrowband multi-channel detector and a spectral resolution of 4 cm^-1. These allow the measurement of the CO₂ concentration at the entrance to the sensor chamber, the CO concentration at the exit from the sensor chamber and respectively the molecular intensities for CO₂ at the entrance and exit of the test chamber under conditions of 0% RH and 50% RH.

Corroborating the experimental results, we can assume that following the surface interaction between CO₂ and the previously adsorbed species of O^- and OH^-, CO₃^- and HCO₃^- result as reaction products, respectively.

Activity 3.2. – The relation between extrinsic parameters of the sensor and intrinsic properties.

The comparison between the two synthesis methods involves morpho-structural aspects, sensitivity to CO₂ and detection mechanisms mediated by RH. Based on previous investigations, we selected Gd₂O₃ based on the sensitivity to CO₂ translated by the variation of the surface band-bending and of the sensor signal, respectively. The relationship between these extrinsic parameters and the intrinsic properties was addressed through a comparative analysis between Gd₂O₃-CoP and Gd₂O₃-HT. Regardless of the synthesis method, the obtained powders consist of rod-shaped particles with lateral dimensions in the range of 10-65 nm and lengths greater than or equal to 1.5 microns. Although the two powders consist of the same crystallographic phase, a significant difference in the degree of crystallization can be observed in both electron diffraction patterns and TEM images at higher magnification. The SAED pattern of the Gd₂O₃-CoP powder contains diffraction rings with a rather diffuse appearance compared to the sharp diffraction rings of the Gd₂O₃-HT sample. This fact indicates a rather weak degree of crystallization of the Gd₂O₃-CoP nanorods. XRD analysis shows that both samples exhibit the characteristic diffraction pattern of Gd₂O₃, which has a cubic structure and space group of I213 symmetry. The diffraction peaks are associated with a higher degree of crystallinity for Gd₂O₃-HT compared to Gd₂O₃-CoP. According to the Rietveld refinement analysis, the lattice parameters are not significantly changed by the synthesis method, while the average size of the nanorods is d=35.3±0.5 nm for Gd₂O₃-HT, substantially larger than that of Gd₂O₃-CoP with only d=5.8±0.2 nm. The average size of the nanorods is following the TEM measurements. The elemental composition and homogeneity of the samples were analyzed by STEM-EDS. From the point of view of CO₂ detection, the study highlights the increase of the sensor signal from 2.95 to 4.42 simply by using the hydrothermal method as an alternative synthesis route.

Regarding SnO₂, we approached the improvement of the sensitive performance through a technological method, namely by reducing the interdigital gap between the platinum electrodes with which the sensor substrate is provided. We used substrates with alternate digital gaps of 100, 30 and 10 microns. We mention that the sensor made by screen printing the thick and porous layer of SnO₂ on a substrate with an interdigital gap of the Pt electrodes of 10 microns is the subject of the patent application OSIM/No. A 00110/18 March 2024, "Senzor de prag pentru detecţia CO₂ şi procedeu de obţinere".

Corroborating these results with those presented previously, Gd₂O₃-HT was selected to identify the charge transfer mechanism induced by CO₂ to the surface. We started from the reference situation (dry synthetic air) and went up to air with 70% RH. We dynamically dosed CO₂ in progressive concentrations for each humidity. There are two significant findings regarding the electrical behaviour of the Gd₂O₃ layer. First, the electrical resistance decreases as the %RH in the air increases. Second, when the Gd₂O₃ layer is exposed to increasing concentrations of CO₂ in the presence of fixed RH levels (between 10-70%), the electrical resistance increases. It is worth noting that the maximum variation in electrical resistance occurs at 400 ppm CO₂, with saturation becoming evident as the concentration increases. These observations confirm the reducing character of the RH specific for n-type MOS and suggest that under humid conditions, CO₂ causes the surface oxidation of Gd₂O₃. We confirmed this hypothesis by demonstrating the preservation of the n-type characteristic conduction mechanism for Gd₂O, regardless of background relative humidity. For this, we recorded the surface band-bending variations at different levels of relative humidity and carbon dioxide. To gain insight into the impact of variable RH levels on resistance behaviour, we first examine the changes in resistance in the air with variable RH and then the resistance behaviour in the air with carbon dioxide at different %RH. In the reducing case of exposure to RH=10, 30, 50, and 70%, the band-bending variation was calculated under the assumption of the Boltzmann statistic distribution and the intergranular Schottky barrier model. In the oxidising case of progressive exposure to CO₂ (400, 600, 800, 1000, 2000, 3000 ppm) band-bending variations were approached under each %RH. We have thus demonstrated that the charge carrier depletion layer in the vicinity of the surface, specific for n-type MOS, governs the conduction mechanism both in the case of RH and in the case of CO₂, following the theoretical model.

Member of the doctoral committee of Drd. Cătălina G. Mihalcea, research assistant in Laboratory 70 - Atomic Structures and Defects in Advanced Materials (LASDAM), INCDFM. Dr. Cătălina G. Mihalcea carries out her activity in the research topic of the group in which she is included, of the CERIC-ERIC and PN-III-P4-PCE-2021-0384 projects. The topic of the doctoral thesis is "Nanostructured materials for gas sensing: correlations between functional, electronic and microstructural properties" and it is carried out under the guidance of the supervisor Prof. C. M. Teodorescu, at the Doctoral School of Physics, University of Bucharest.

ISI papers:

1. Corneliu Ghica, Catalina G. Mihalcea, Cristian E. Simion, Ioana D. Vlaicu, Daniela Ghica, Ion V. Dinu, Ovidiu G. Florea, Adelina Stanoiu*, Influence of relative humidity on CO₂ interaction mechanism for Gd-doped SnO₂ with respect to pure SnO₂ and Gd₂O₃, Sens. Actuators B. Chem. 368, 1 October 2022, 132130, https://doi.org/10.1016/j.snb.2022.132130
2. Andrei C. Kuncser, Ioana D. Vlaicu, Ion V. Dinu, Cristian E. Simion, Alexandra C. Iacoban, Ovidiu G. Florea, Adelina Stanoiu*, The impact of the synthesis temperature on SnO₂ morphology and sensitivity to CO₂ under in-field conditions, Materials Letters 325, 15 October 2022, 132855, https://doi.org/10.1016/j.matlet.2022.132855
3. Adelina Stanoiu, Corneliu Ghica, Catalina Gabriela Mihalcea, Daniela Ghica and Cristian Eugen Simion*, The Role of the Synthesis Routes on the CO-Sensing Mechanism of NiO-Based Gas Sensors, Chemosensors 10 (11), 9 November 2022, 466, https://doi.org/10.3390/chemosensors10110466
4. Cristian E. Simion, Ioana D. Vlaicu, Alexandra C. Iacoban, Catalina G. Mihalcea, Corneliu Ghica and Adelina Stanoiu*, The influence of the synthesis method on Gd₂O₃ morpho-structural properties and sensitivity to CO₂ under in-field conditions, Materials Chemistry and Physics 296, 15 February 2023, 127354, https://doi.org/10.1016/j.matchemphys.2023.127354
5. Cristian.E. Simion, Benjamin Junker, Udo Weimar, Adelina Stanoiu, Nicolae Bârsan, Sensing mechanisms of CO and H₂ with NiO material – DRIFTS investigations, Sens. Actuators B. Chem. 390 , 1 September 2023, 134028, https://doi.org/10.1016/j.snb.2023.134028
6. Ion V. Dinu, Cristian E. Simion, Nicoleta G. Apostol, Ovidiu G. Florea, Catalina G. Mihalcea and Adelina Stanoiu, Conduction mechanism of Gd₂O₃ induced by CO₂ under in-field conditions, Physica E 157 , March 2024, 115862, https://doi.org/10.1016/j.physe.2023.115862
7. Catalina G. Mihalcea, Mariana Stefan, Corneliu Ghica, Ovidiu G. Florea, Adelina Stanoiu, Cristian E. Simion, Simona Somacescu, Daniela Ghica, In-depth insight into the structural properties of nanoparticulate NiO for CO sensing, Appl. Surf. Sci. 651, 1 April 2024, 159252, https://doi.org/10.1016/j.apsusc.2023.159252
8. Cristian Eugen Simion, Catalina Gabriela Mihalcea, Alexandra Corina Iacoban, Ion Viorel Dinu, Daniela Predoi, Ioana Dorina Vlaicu, Ovidiu Gabriel Florea, and Adelina Stanoiu, Influence of the synthesis method and electrode geometry on GHG-sensing properties of 5%Gd-doped SnO₂, Chemosensors 12(8), 1 August 2024, 148, https://doi.org/10.3390/chemosensors12080148
9. A. Stanoiu, A. C. Iacoban, C. G. Mihalcea, I. V. Dinu, O. G. Florea, I. D. Vlaicu, C. E. Simion, CO₂ interaction mechanism of SnO₂-based sensors with respect to the Pt interdigital electrodes gap, Chemosensors 12, 16 November 2024, 238. https://doi.org/10.3390/chemosensors12110238

Papers under review at ISI journals:

1. Ghica, M. Stefan, A. Stanoiu, C. Simion, I. Vlaicu, N. Apostol, C. Mihalcea, A. Iacoban, O. Florea, S. Bulat, Correlative spectroscopic and morpho-structural investigation at atomic scale of surface defects and faceting in SnO₂ nanoparticles for NO₂ sensing, under review at Applied Surface Science from October 2024, Manuscript Number: APSUSC-D-24-12687

Papers presented at conferences:

1. Catalina G. Mihalcea*, Corneliu Ghica, Cristian E. Simion, Ioana D. Vlaicu, Daniela Ghica, Ion V. Dinu, Ovidiu G. Florea, Adelina Stanoiu, The structure and morphology of pure SnO₂, Gd-doped SnO₂ and pure Gd₂O₃ nanoparticles for applications in chemoresistive gas sensors, oral presentation at the 19th International conference on Advanced Nanomaterials ANM 2022, July 27-29, University of Aveiro, Aveiro – Portugal
2. Catalina G. Mihalcea*, Corneliu Ghica, Cristian E. Simion, Ioana D. Vlaicu, Daniela Ghica, Ion V. Dinu, Ovidiu G. Florea, Adelina Stanoiu, Structural and morphological properties of Gd-doped SnO₂ nanopowders and their role in the gas sensing mechanism, poster session 2 at the 9th International Conference on Optical, Optoelectronic and Photonic Materials and Applications & 14th Europhysical Conference on Defects in Insulating Materials ICOOPMA-EURODIM 2022, July 3–8, Ghent, Belgium
3. Catalina Gabriela Mihalcea, Corneliu Ghica, Adelina Stanoiu, Cristian Eugen Simion, Ioana Dorina Vlaicu, Alexandra Corina Iacoban, Daniela Ghica, Ionel Florinel Mercioniu, Morphology and structure of SnO₂-based nanomaterials obtained by different synthesis routes for gas sensing applications, poster session at the 2023 Fall Meeting of the European Materials Research Society (E-MRS), September 18-21, Warsaw, Poland
4. A. Stanoiu, D. Ghica, C.G. Mihalcea, I.D. Vlaicu, O.G. Florea, S. Bulat, C. Ghica, C.E. Simion, GHGs detection by tuning the operating temperature of Sn_1-xGd_xO_(4-x)/2, oral presentation at the 2023 International Semiconductor Conference (CAS) ⁴⁶th Edition, 11-13 October, Sinaia, Romania, Proceedings of the IEEE, November 2023, pp. 63-66, https://doi.org/10.1109/CAS59036.2023.10303672
5. C.E. Simion, I.V. Dinu, O.G. Florea, A. Stanoiu, The role of interdigital electrodes on sensing performances with p-type NiO-based gas sensors – link to experiments, oral presentation at the 2023 International Semiconductor Conference (CAS) ⁴⁶th Edition, 11-13 October, Sinaia, Romania, Proceedings of the IEEE, November 2023, pp. 11-18, https://doi.org/10.1109/CAS59036.2023.10303715
6. Catalina Gabriela Mihalcea, Adelina Stanoiu, Cristian Eugen Simion, Daniela Ghica, Ioana Dorina Vlaicu, Alexandra Corina Iacoban, Corneliu Ghica, “Correlations between the synthesis route, morphology, structure and electrical properties of SnO₂-Gd₂O₃ nanocomposites for applications in gas sensing”, oral presentation at the 10th International conference on advanced materials: ROCAM 2024, July 15 – 18, Bucharest, Romania.
7. Catalina Gabriela Mihalcea, Corneliu Ghica, Adelina Stanoiu, Cristian Eugen Simion, Daniela Ghica, Mariana Stefan, Simona Somacescu, Ioana Dorina Vlaicu, Alexandra Corina Iacoban, “Analytical TEM of materials for gas sensing”, poster session at the 17th European Microscopy Congress 2024, August 25 – 30, Copenhagen, Denmark.
8. Catalina G. Mihalcea, Corneliu Ghica, Daniela Ghica, Ioana Dorina Vlaicu and Alexandra Corina Iacoban, “The influence of the synthesis route on the morphology and structure of Gd-doped SnO₂ for gas sensing applications”, poster session at the Conference on Electron Microscopy of Nanostructures ELMINA 2024, September 9 – 13, Belgrade, Serbia

1. Adelina Stănoiu, Ovidiu Gabriel Florea, Cristian Eugen Simion, Ion Viorel Dinu, Senzor de prag pentru detecţia CO₂ şi procedeu de obţinere, OSIM A/00110/18 Mar 2024

Experimental methods for investigating gas-sensing properties under in-field conditions - NIMP facilities:

https://infim.ro/wp-content/uploads/2022/11/Gas-Mixing-Station-scaled.jpg

Dr. Adelina Stănoiu

adelina.stanoiu@infim.ro

stanoiu.adelina@yahoo.com