scholarly journals Electrical conductivity and temperature sensitivity of Cu/Mo co-modified YFeoO ceramics

2021 ◽  
Vol 15 (2) ◽  
pp. 195-201
Author(s):  
Yuan Zeng ◽  
Zhicheng Li ◽  
Caiyun Gao ◽  
Guoxiang Jiang ◽  
Hong Zhang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Negative Temperature ◽  
Xrd Analysis ◽  
Temperature Sensitive ◽  
Room Temperature Resistivity ◽  
Polaron Hopping ◽  
Wet Chemical Synthesis ◽  
Valence States ◽  
Wet Chemical ◽  
Electrical Conduction Mechanisms

To develop a new kind of thermistor with the negative temperature coefficient (NTC) behaviour, the Cu/Mo co-doped YFeO3 based ceramics were prepared by wet-chemical synthesis and sintering at 1300?C. The orthorhombic perovskite structure was identified in all ceramics by XRD analysis. The possible valence states of Fe, Cu and Mo in the doped YFeO3 compounds were examined by X-ray photoelectron spectroscopy. By adjusting the concentration of Cu- and Mo-ions, the room temperature resistivity (?25) and temperature-sensitive constant (B25/85) can be modified from 1.13?103 to 3.09?105 ??cm and 3000 to 7000K, respectively. The complex impedances at various temperatures (from 25 to 150?C) are tested and analysed. The results show that both grain and grain boundary exhibit the NTC characteristics. The electrical conduction mechanisms composing of polaron hopping conduction and band conduction were proposed in the YFeO3 based ceramics.

scholarly journals Nanocrystallization of Vanadium Borophosphate Glass for Improving the Electrical and Catalytic Properties

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Su-Yeon Choi ◽  
Bong-Ki Ryu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Catalytic Effect ◽  
Xrd Analysis ◽  
Annealed Sample ◽  
Molecular Volume ◽  
X Ray ◽  
Valence States ◽  
Heat Treated ◽  
Structural And Electrical Properties

75V2O5-10P2O5-15B2O3ternary-system glasses were prepared and nanocrystallized to examine the catalytic effect and the variations in their structural and electrical properties. These glasses were annealed in a graphite mold above the glass transition temperature for 2 h and heat-treated at the crystallization temperature for 1, 3, and 5 h. Fourier transform infrared spectroscopy (FTIR) was used to analyze the structural changes in the B-O bonds after nanocrystallization, while X-ray photoelectron spectroscopy (XPS) analysis showed a decrease in V5+and an increase in V4+. X-ray diffraction (XRD) analysis of the structure array (BO3+ V2O5  ↔BO4+ 2VO2) verified these inferred changes. Structural changes induced by the heat treatment were confirmed by analyzing the molecular volume determined from the sample density. Conductivity and catalytic effects were discussed based on the migration of vanadate ions with different valence states due to the increase in VO2nanocrystallinity at 275°C. Both conductance and the catalytic effect were higher after nanocrystallization at 275°C for 1 h compared to the annealed sample. Furthermore, compared to the sample heat-treated for 1 h, the conductance and catalytic effect were increased and decreased, respectively, for samples nanocrystallized at 275°C for 3 and 5 h.

scholarly journals Electrical properties of Nb/Al-doped CuO-based ceramics for NTC thermistors

2020 ◽  
Vol 14 (1) ◽  
pp. 47-55
Author(s):  
Xianchi Wang ◽  
Zhicheng Li ◽  
Weiqin Yan ◽  
Pinji Wang ◽  
Hong Zhang
Keyword(s):  
Electrical Properties ◽  
Photoelectron Spectroscopy ◽  
Boundary Effect ◽  
Sol Gel ◽  
Complex Impedance ◽  
Negative Temperature ◽  
Impedance Analysis ◽  
B Value ◽  
Polaron Hopping ◽  
Ntc Thermistors

Nb/Al-modified CuO ceramics (yNb/0.02Al-CuO, 0 ? y ? 0.07, denoted as NACO) were synthesized using sol-gel method for applications in negative temperature coefficient (NTC) thermistors. The phase structure, microstructure and electrical properties of the ceramics were investigated. XRD investigation reveals that the NACO ceramics has the main phase with monoclinic crystalline structure. The analysis of X-ray photoelectron spectroscopy proved the existence of Cu2+/Cu+ and Nb5+/Nb4+ ions. Temperature dependence of the resistivity indicated that the NACO ceramics present typical NTC characteristic. The NTC materials? constant, B value, can be adjusted from 2430K to 3805K by changing the Nb-concentration in the Al-doped CuO ceramics. Among four applied calibration equations the Hoge-3 equation is the most effective one for the resistancetemperature calibration of the prepared NTC thermistors. The complex impedance analysis was performed and revealed that both grain effect and grain boundary effect similarly contribute to the electrical conductive behaviour and NTC feature of the NACO ceramics. The band conduction and polaron hopping conduction are proposed as the conduction mechanisms in the NACO thermistors.

Wet Chemical Synthesis of SnS/Graphene Nanocomposites for High Performance Supercapacitor Electrodes

2017 ◽  
Vol 17 (01n02) ◽  
pp. 1760022 ◽  
Author(s):  
Syamsai Ravuri ◽  
Chandan Abhishek Pandey ◽  
R. Ramchandran ◽  
Soon Kwan Jeon ◽  
Andrews Nirmala Grace
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Chemical Route ◽  
Graphene Nanocomposites ◽  
X Ray ◽  
Wet Chemical Synthesis ◽  
Transmission Electron ◽  
Discharge Duration ◽  
Wet Chemical ◽  
Charge Discharge

A series of SnS/Graphene (SnS/G) nanocomposites at various concentrations of graphene were synthesized by a wet chemical route and the prepared composites were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), High Resolution Transmission Electron Microscopy (HRTEM) for its structural and morphological investigation. Results show that the prepared SnS nanoparticles in the composite are [Formula: see text]30[Formula: see text]nm sized and uniformly dispersed on graphene sheets. To test the supercapacitance behavior, electrochemical measurements were carried out in 6[Formula: see text]M KOH electrolyte. A maximum specific capacitance of 984[Formula: see text]F/g was observed for SnS/G-c at 5[Formula: see text]mVs[Formula: see text] scan rate. Galvanostatic charge/discharge curves showed an excellent cyclic stability with higher charge/discharge duration, and hence could be used for high performance supercapacitor applications.

scholarly journals A novel and potentially scalable CVD-based route towards SnO2:Mo thin films as transparent conducting oxides

2021 ◽  
Author(s):  
Tianlei Ma ◽  
Marek Nikiel ◽  
Andrew G. Thomas ◽  
Mohamed Missous ◽  
David J. Lewis
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Mixed Valence ◽  
Chemical Vapour ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conducting Oxides ◽  
Valence States ◽  
3 Omega ◽  
First Time

AbstractIn this report, we prepared transparent and conducting undoped and molybdenum-doped tin oxide (Mo–SnO2) thin films by aerosol-assisted chemical vapour deposition (AACVD). The relationship between the precursor concentration in the feed and in the resulting films was studied by energy-dispersive X-ray spectroscopy, suggesting that the efficiency of doping is quantitative and that this method could potentially impart exquisite control over dopant levels. All SnO2 films were in tetragonal structure as confirmed by powder X-ray diffraction measurements. X-ray photoelectron spectroscopy characterisation indicated for the first time that Mo ions were in mixed valence states of Mo(VI) and Mo(V) on the surface. Incorporation of Mo6+ resulted in the lowest resistivity of $$7.3 \times 10^{{ - 3}} \Omega \,{\text{cm}}$$ 7.3 × 10 - 3 Ω cm , compared to pure SnO2 films with resistivities of $$4.3\left( 0 \right) \times 10^{{ - 2}} \Omega \,{\text{cm}}$$ 4.3 0 × 10 - 2 Ω cm . Meanwhile, a high transmittance of 83% in the visible light range was also acquired. This work presents a comprehensive investigation into impact of Mo doping on SnO2 films synthesised by AACVD for the first time and establishes the potential for scalable deposition of SnO2:Mo thin films in TCO manufacturing. Graphical abstract

scholarly journals Canted antiferromagnetism in high-purity NaFeF3 prepared by a novel wet-chemical synthesis method

2020 ◽  
Vol 4 (11) ◽  
Author(s):  
Fabian L. M. Bernal ◽  
Bruno Gonano ◽  
Fredrik Lundvall ◽  
David S. Wragg ◽  
Helmer Fjellvåg ◽  
...  
Keyword(s):  
Chemical Synthesis ◽  
High Purity ◽  
Synthesis Method ◽  
Wet Chemical Synthesis ◽  
Wet Chemical

scholarly journals Yttrium doped phosphate-based glasses: structural and degradation analyses

2020 ◽  
Vol 6 (1) ◽  
pp. 34-49
Author(s):  
Abul Arafat ◽  
Sabrin A. Samad ◽  
Jeremy J. Titman ◽  
Andrew L. Lewis ◽  
Emma R. Barney ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Xrd Analysis ◽  
Calcium Pyrophosphate ◽  
Ion Release ◽  
Subsequent Increase ◽  
Structural Characterisation ◽  
Release Studies ◽  
Degradation Properties

AbstractThis study investigates the role of yttrium in phosphate-based glasses in the system 45(P2O5)–25(CaO)– (30-x)(Na2O)–x(Y2O3) (0≤x≤5) prepared via melt quenching and focuses on their structural characterisation and degradation properties. The structural analyses were performed using a combination of solid-state nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). 31P NMR analysis showed that depolymerisation of the phosphate network occurred which increased with Y2O3 content as metaphosphate units (Q2) decreased with subsequent increase in pyrophosphate species (Q1). The NMR results correlated well with structural changes observed via FTIR and XPS analyses. XRD analysis of crystallised glass samples revealed the presence of calcium pyrophosphate (Ca2P2O7) and sodium metaphosphate (NaPO3) phases for all the glass formulations explored. Yttrium-containing phases were found for the formulations containing 3 and 5 mol% Y2O3. Degradation analyses performed in Phosphate buffer saline (PBS) and Milli-Q water revealed significantly reduced rates with addition of Y2O3 content. This decrease was attributed to the formation of Y-O-P bonds where the octahedral structure of yttrium (YO6) cross-linked phosphate chains, subsequently leading to an increase in chemical durability of the glasses. The ion release studies also showed good correlation with the degradation profiles.

scholarly journals An Insight into Chemistry and Structure of Colloidal 2D-WS2 Nanoflakes: Combined XPS and XRD Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1969
Author(s):  
Riccardo Scarfiello ◽  
Elisabetta Mazzotta ◽  
Davide Altamura ◽  
Concetta Nobile ◽  
Rosanna Mastria ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Xrd Analysis ◽  
Crystal Habit ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Evaluation ◽  
Rational Understanding ◽  
Structural Inspection

The surface and structural characterization techniques of three atom-thick bi-dimensional 2D-WS2 colloidal nanocrystals cross the limit of bulk investigation, offering the possibility of simultaneous phase identification, structural-to-morphological evaluation, and surface chemical description. In the present study, we report a rational understanding based on X-ray photoelectron spectroscopy (XPS) and structural inspection of two kinds of dimensionally controllable 2D-WS2 colloidal nanoflakes (NFLs) generated with a surfactant assisted non-hydrolytic route. The qualitative and quantitative determination of 1T’ and 2H phases based on W 4f XPS signal components, together with the presence of two kinds of sulfur ions, S22− and S2−, based on S 2p signal and related to the formation of WS2 and WOxSy in a mixed oxygen-sulfur environment, are carefully reported and discussed for both nanocrystals breeds. The XPS results are used as an input for detailed X-ray Diffraction (XRD) analysis allowing for a clear discrimination of NFLs crystal habit, and an estimation of the exact number of atomic monolayers composing the 2D-WS2 nanocrystalline samples.

ChemInform Abstract: Wet Chemical Synthesis of Highly Luminescent HgTe/CdS Core/Shell Nanocrystals.

ChemInform ◽  
2010 ◽  
Vol 31 (20) ◽  
pp. no-no
Author(s):  
Mike T. Harrison ◽  
Steve V. Kershaw ◽  
Andrey L. Rogach ◽  
Andreas Kornowski ◽  
Alex Eychmueller ◽  
...  
Keyword(s):  
Chemical Synthesis ◽  
Core Shell ◽  
Wet Chemical Synthesis ◽  
Wet Chemical
Sign in / Sign up

Export Citation Format

Share Document