Type Of Electrical Conductivity Research Articles

Comparative Study of Physicochemical Properties of Finely Dispersed Powders and Ceramics in the Systems CeO2–Sm2O3 and CeO2–Nd2O3 as Electrolyte Materials for Medium Temperature Fuel Cells

Finely dispersed (CeO2)1−x(Sm2O3)x (x = 0.05, 0.10, 0.20) and (CeO2)1−x(Nd2O3)x (x = 0.05, 0.10, 0.15, 0.20, 0.25) powders were synthesized via liquid-phase techniques based on the co-precipitation of hydroxides and were used to obtain ceramic materials comprising fluorite-like solid solutions with CSR in the range 69–88 nm (upon annealing at 1300 °C) and open porosity in the range 0.6–6.2%. The physicochemical properties of the synthesized materials were comparatively characterized. In general, the prepared materials were found to possess a mixed type of electrical conductivity, but in the medium-temperature range, the ionic component was predominant (ion transfer numbers ti = 0.93–0.73 at 300–700 °C). The highest ionic conductivity was observed for CeO2-based samples containing 20 mol.% Sm2O3 (σ700°C = 3.3 × 10−2 S/cm) and 15 mol.% Nd2O3 (σ700°C = 0.48 × 10−2 S/cm) was in the temperature range 500–700 °C. The physicochemical properties (density, open porosity, type and mechanism of electrical conductivity) of the obtained ceramic materials make them promising as solid oxide electrolytes for medium temperature fuel cells.

Effect of Synthetic Approaches and Sintering Additives upon Physicochemical and Electrophysical Properties of Solid Solutions in the System (CeO2)1−x(Nd2O3)x for Fuel Cell Electrolytes

Finely dispersed (CeO2)1−x(Nd2O3)x (x = 0.05, 0.10, 0.15, 0.20, 0.25) powders are synthesized via liquid-phase techniques based on the co-precipitation of hydroxides and co-crystallization of nitrates. The prepared powders are used to obtain ceramic materials comprising fluorite-like solid solutions with the coherent scattering region (CSR) of about 88 nm (upon annealing at 1300 °C) and open porosity in the range of 1–15%. The effect of the synthesis procedure and sintering additives (SiO2, ZnO) on physicochemical and electrophysical properties of the resulting ceramics is studied. The prepared materials are found to possess a predominantly ionic type of electric conductivity with ion transfer numbers ti = 0.96–0.71 in the temperature range of 300–700 °C. The conductivity in solid solutions follows a vacancy mechanism with σ700 °C = 0.48 × 10−2 S/cm. Physicochemical properties (density, open porosity, type and mechanism of electrical conductivity) of the obtained ceramic materials make them promising as solid oxide electrolytes for medium temperature fuel cells.

SCAPS 3201 simulation of tunable heterostructured p-CdTe and n-CdS thin films-based solar cells

This paper presents a numerical simulation using SCAPS 3201 and an electrometer for the investigation of electrical behavior at the interface of heterostructured Cadmium telluride and cadmium sulfide thin films. The paper also explicitly compares the theoretical and experimental results of the synthesized materials via the electrodeposition route. Parameters such as electrical conductivity types and energy band gaps used in the simulation were obtained from the various analytical procedure employed in contrast to the conventional mode of application of the SCAPS simulation. In most research works on CdTe/CdS-based solar cells, the conductivity type, p-type, and n-type used in the SCAPS simulation were based on assumption. However, in this study, photoelectrochemical (PEC) cell measurement of the material's conductivity type helped in the identification of p-type CdTe and n-type CdS. The material's properties were examined using an X-ray Diffractometer (XRD), scanning electron microscopy (SEM), ultraviolet–visible spectrophotometer (UV-VIS), (PEC), and electrometer. The energy band gaps at varied cathodic potentials and the grain size of the CdTe thin films were estimated as 1.47–1.89 eV and 56 nm while that of the CdS was estimated at 2.37–2.46 eV and 115 nm. The results indicate a noticeable drastic improvement in the performance of electrodeposited p-CdTe and n-CdS thin film-based solar cells, which aid the tuning of the growth potential. The extracted electrical parameters (JSC = 15.22, Voc = 749, FF = 0.82 and QE = 9.0% at 520 nm) using SCAPS and electrometer are evidence of the improvement made and the results from both the SCAPS and electrometer are in tandem.

Synthesis, crystal structure and dielectric properties of a hybrid dihydrogen arsenate salt: (C9H11N4)H2AsO4

The use of the organic aromatic amine molecule 5-amino-3-methyl-1-phenyl-1H-1,2,4-triazole to synthesize a dihydrogen arsenate hybrid salt leads to a supramolecular structure type. Single crystals of (C9H11N4)H2AsO4 were grown through slow evaporation in solution. The synthesized compound crystallizes in the monoclinic system with the non-centrosymmetric P21 space group according to the following parameters; a = 9.655 (3) Å, b = 4.7090 (15) Å, c = 14.022 (4) Å, β = 108.147 (5)° and Z = 4. The mineral part building from dihydrogen arsenate anions [H2AsO4]− is linked together and to the organic cations [C9H11N4]+ by hydrogen bonds only. The results of Hirshfeld’s analysis show that in all possible molecular contacts, the hydrogen–hydrogen and the oxygen–hydrogen are the most important interaction in the crystal (37.5 and 31.9%, respectively). The Fourier transform infrared (FT-IR) confirms the existence of vibrational modes corresponding to the organic amine molecule and mineral arsenate tetrahedron. The optimized molecular structure and the vibrational spectra were calculated by the density functional theory DFT methods and the semi-empirical PM3 calculations. Dielectric study of this compound has been measured in order to determine the electrical conductivity type giving rise to an activation energy of ΔEσ = 0.17 eV.

ОПРЕДЕЛЕНИЕ ТИПА ПРОВОДИМОСТИ КОМПОЗИЦИОННОГО ОПТИЧЕСКИ ПРОЗРАЧНОГО ПРОВОДЯЩЕГО ПОКРЫТИЯ НА ОСНОВЕ ОРИЕНТИРОВАННЫХ СЕТЕЙ ПЛАТИНЫ

This paper considers a method for determining the type of electrical conductivity of a previously developed composite transparent conductive coating based on oriented platinum networks embedded in the polymer matrix. Many researchers have recently been grappling with finding electrically conductive transparent coatings for smart devices with touch screens, particularly an alternative to the massively used indium tin oxide (ITO) having some disadvantages, the most serious of which is the lack of coating flexibility. The latter can be overcome by using various metal-polymer composites with high transparency in the optical range and low surface resistance. However, one should be aware that the type of conductivity depends on both the polymer matrix and the metal framework of a composite. This defines its electrical properties. Therefore, it is important to correctly identify and measure the electrical conductivity. The developed method is based on studying the temperature dependence of the surface resistance in the material.

Effect of Annealing on the Microstructure, Opto-Electronic and Hydrogen Sensing Properties of V2O5 Thin Films Deposited by Magnetron Sputtering

This paper reports results of investigations on selected properties of vanadium oxide thin films deposited using gas impulse magnetron sputtering and annealed at temperatures in the range of 423 K to 673 K. Post-process annealing was shown to allow phase transition of as-deposited films from amorphous to nanocrystalline V2O5 with crystallite sizes in the range of 23 to 27 nm. Simultaneously, annealing resulted in an increase in surface roughness and grain size. Moreover, a decrease in transparency was observed in the visible wavelength range of approximately 50% to 30%, while the resistivity of formed vanadium pentoxide thin films was almost unchanged and was in the order of 102 Ω·cm. Simultaneously, the best optoelectronic performance, testified by evaluated figure of merit parameter, indicated the as-deposited amorphous films. Performed Seebeck coefficient measurements indicated the electron type of electrical conduction of each prepared thin film. Furthermore, gas sensing properties towards diluted hydrogen were investigated for annealed V2O5 thin films, and it was found that the highest senor response was obtained for a thin film annealed at 673 K and measured at operating temperature of 623 K.

An oxygen vacancy defect and chalcogens impurities in earth-abundant lead-free calcium zirconate perovskite for non-toxic solar cells: First-principles calculations

The effects of an oxygen vacancy (Ov), and chalcogens impurities on electronic, optical properties, thermodynamic stability, and photocatalytic hydrogen production form water splitting ability of non-toxic lead-free calcium zirconate perovskite CaZrO 3 are investigated using first-principles calculations-based Density Functional Theory and LDA+TB-mBJ functional. It is found that an Ov itself in CaZrO 3 compound results of free electrons inside the unoccupied states in CB which changed the type of electrical conductivity from p to n-type. Besides, the wide forbidden band energy of CaZrO 3 was effectively reduced when chalcogens impurities doped CaZrO 3 with the presence of an Ov. Furthermore, the optical properties show that the percentage of the transmittance reduced while the absorption coefficient’s percentage increased along the visible spectrum in all structures having an Ov, suggesting that Ov creates free charge carriers in the CaZrO 3 compound. In Addition, the formation energy confirms that all studied structures are thermodynamically stables. Finley, S/Se@OI/OII/OIII+Ov structures are promising photocatalysts to drive water splitting reactions as they are distinguished by their appropriate forbidden bands, visible light absorption, and band edge positions. We believe that our study could be used to give CaZrO 3 the opportunity to be used as a semiconductor for photovoltaic and photocatalytic applications.

Best practices for correlating electrical conductivity with broadband EMI shielding in binary filler-based conducting polymer composites

Multiple conductive fillers (MWCNT, GNP, Cu@Ag dendrite, EGain) were incorporated in a commercial polypropylene matrix through melt processing. Electrical conductivity, thermal conductivity, and EMI shielding properties of the fabricated composites were examined according to various filler compositions, and it was confirmed that the properties varied according to shape, composition, and mutual compatibility of the particulate fillers. In particular, at broadband frequencies (X-, Ka-, W- band), the EMI shielding properties reached 32.6 dB (at 10 GHz), 39.3 dB (at 28 GHz), 51.1 dB (at 77 GHz) for composites comprising of PC15 (0.3 mm) and the EMI shielding mechanisms according to the material thickness (0.3, 0.5, 1 mm) and the filler content were studied. As the frequency increased from 8.2–110 GHz, the reflection properties decreased from 90.93 % to 80.99 % (at 0.3 mm), and the absorption properties increased 9.01 % to 19.01 % even for PC15 (0.3 mm). In particular, the correlation between the type of electrical conductivity and the EMI shielding properties were investigated using a theoretical (Simon, Drude) model.

Probing the electronic properties of chemically synthesised doped and undoped graphene derivative

Controlled oxidation and reduction are both responsible in determining the distribution of functional groups in graphene derivatives. These functional groups are accountable for showing different types of electrical conductivity in reduced graphene oxide (rGO) and nitrogen-doped rGO (N-rGO). The study reports a new approach to obtain different electronic grades of N-rGO by simply treating rGO with ammonia solution at different temperatures. Using Hall measurements, the electrical properties of rGO and N-rGO are examined, and their conductivity type, sheet carrier density, and resistivity are calculated. The presence of oxygen-containing functional groups causes p-type conductivity in rGO but N-rGO possesses a completely different set of electronic properties due to differently aligned nitrogen-atoms in the exfoliated layers. The amount of ammonia used and the temperature at which it is synthesised are both important in the synthesis of N-rGO. Complete n-type conductivity or compensated n-type conductivity is observed in different types of N-rGOs.

Structural and Electric Properties of Ba-Fe-Ta-Na-Bi-Ti-O Ceramic System

The X-ray diffraction, microstructure, impedance, electric modulus, and ac-conductivity of Ba(Fe1/2Ta1/2)O3–(Na1/2Bi1/2)TiO3 solid-solutions were studied utilising a traditional high-temperature mixed-oxide technique. The phase-formations of the solid-solutions were determined utilising X-ray data, while SEM micrographs revealed a non-uniform dispersion of grains in the sample of unequal size (~1 – 20 mm). In all of the developed solid-solutions, the frequency (1Hz - 1MHz) dependence of imaginary and real parts of electric impedance in the temperature region of 50 and 500°C showed the NTCR character and hopping type of electrical conduction. The modulus spectrum variation was intrigued by the hopping mechanism for charge transport (temperature-dependent) in the samples with non-Debye type of behaviour. Besides, the low electrical conductivity of these solid-state solutions makes them ideal for industrial applications, particularly as capacitors.

Features of the Transport Properties of Thermoelectric Nanocomposites Based on a Matrix from BiSbTe1.5Se1.5 Medium-Entropy Alloy and Carbon-Nanotube Filler

For the first time, thermoelectric nanocomposites consisting of a BiSbTe1.5Se1.5 medium-entropy alloy (nanocomposite matrix) and “Taunit-M”, CNT carbon nanotubes (nanocomposite filler)are obtained. All BiSbTe1.5Se1.5 + xCNT nanocomposites with different filler contents (x = 0, 0.05, 0.1, 0.5, 1.0, 1.5, and 2.0 wt %), obtained by spark plasma sintering of the initial powders of the matrix material and filler, consist of micron-sized filler inclusions formed from clusters of nanotubes. The inclusions themselves are randomly distributed within the polycrystalline matrix. In the temperature range of 290–500 K, the transport properties (electrical resistivity and total thermal conductivity, including the electronic and phonon contributions, as well as the contribution of bipolar thermal conductivity) of the nanocomposites with various filler contents are studied. It is established that the introduction of CNTs into the matrix leads to a qualitative change in the type of electrical conductivity from “metallic” (electrical resistance increases with temperature), characteristic of the nanocomposite matrix, to “semiconductor” (resistance decreases with temperature), characteristic of nanocomposites. The observed “semiconductor” behavior of the electrical conductivity is characteristic of electrically inhomogeneous systems, in which current transfer is determined by the movement of electrons through the interfaces between the inhomogeneities. For all nanocomposites with different filler contents, the temperature dependences of the total thermal conductivity are qualitatively similar. At low temperatures, they are determined by the phonon contribution; at high temperatures, by the bipolar-thermal-conductivity contribution; the electronic contribution manifests itself at all temperatures, but it gradually decreases with increasing x. The minimum thermal conductivity is observed for the nanocomposite with x = 0.5 at % CNT.

STUDIES OF THERMOMETRIC MATERIAL Lu1-xZrxNiSb

The results of experimental research of perspective thermometric material Lu1-xZrxNiSbwhich can be used for the production of sensitive elements of thermoelectric and electroresistive thermometers are presented. Thermometric materials Lu1-xZrxNiSb, x=0.01–0.10, were made by fusing a charge of components in an electric arc furnace with a tungsten electrode (cathode) in an atmosphere of purified argon under a pressure of 0.1 kPa on a copper water-cooled hearth (anode). Heat treatment of alloys consisted of homogenizing annealing at a temperature of 1073 K. Annealing of samples was carried out for 720 h in vacuumed up to 1.0 Pa ampoules of quartz glass in muffle electric furnaces with temperature control with an accuracy of ±10 K. Diffraction arrays were obtained on a diffractometer DRON-4.0 (FeKα radiation), and the structural characteristics of Lu1-xZrxNiSbwere calculated using the Fullprof program. The chemical and phase compositions of the samples were monitored using a scanning electron microscope (Tescan Vega 3 LMU). The study of the temperature dependences of the resistivity ρ(T,x) and the thermopower coefficientα(T,x) Lu1-xZrxNiSb was performed in the temperature range of 80÷400 K on samples in the form of rectangular parallelepipeds measuring ~1.0×1.0×5.0 mm3 . Measurements of the values of the specific magnetic susceptibility χ(x) of Lu1-xZrxNiSb samples were performed by the relative Faraday method at a temperature of 273 K using a thermogravimetric installation with an electronic microbalance EM-5-ZMP in magnetic fields up to 10 kGs. Microprobe analysis of the concentration of atoms on the surface of Lu1-xZrxNiSb samples, x=0.01–0.10, established their correspondence to the initial compositions of the charge, and X-ray phase analysis showed no traces of extraneous phases on the sample diffractograms, except for the main phase. The nonmonotonic nature of the change in the values of the unit cell period of the thermometric material an (x) Lu1-xZrxNiSb, x=0.01–0.10, which differs from the results of modeling structural characteristics using software packages AkaiKKR and Elk. The nonmonotonic change in the values of the period of the unit cell a(x) Lu1-xZrxNiSband the presence of the extremum dependence suggests that the impurity Zr atoms introduced into the matrix of the LuNiSb basic semiconductor can simultaneously occupy partially different crystallographic positions in different ratios. The temperature resistivities ρ and the thermopower coefficientα of the LuNiSb base semiconductor contain high- and lowtemperature activation regions, which is characteristic of doped and compensated semiconductors. The introduction into the LuNiSb structure of the lowest concentration of impurity Zr atoms in the experiment (x=0.01) radically changes both the behavior of the temperature dependences of the resistivity ρ and the thermopower coefficientα and the type of the main electric current carriers. The values of the resistivity ρ(T,x) Lu1-xZrxNiSbonly increase with increasing temperature, which is characteristic of the metallic type of electrical conductivity and is due to the mechanisms of scattering of current carriers. This nature of the change in electrical resistance ρ(T,x) is evidence that the Fermi level εF has left the bandgap εg and is in the conduction band εC. This is indicated by the negative values of thermopower coefficientα(T,x) at all concentrations and temperatures. Studies of the magnetic susceptibility χ(x) showed that the samples as a basic semiconductor LuNiSb, as well as the thermometric material Lu1-xZrxNiSb, at all concentrations of impurities Zr, are Pauli paramagnetic. There is a synchronicity of the behavior of χ(x) with the dependences of the resistivity ρ(x, T) and the thermopower coefficient α(x, T), which is due to the change in the density of states at the Fermi level g(εF). The results of experimental studies of the Lu1-xZrxNiSbthermometric material completely coincide with the results of modeling its kinetic characteristics under the presence of vacancies in the crystallographic positions 4a and 4c of the Lu and Ni atoms, respectively. Such studies allow making adjustments in the structural studies of thermometric material with an accuracy that significantly exceeds the accuracy of X-ray research methods. The obtained results will allow us to clarify the spatial arrangement of atoms in the nodes of the unit cell, as well as to identify the mechanisms of electrical conductivity to determine the conditions for the synthesis of thermosensitive materials with maximum efficiency of thermal energy conversion into electricity.

High ZT and performance controllable thermoelectric devices based on electrically gated bismuth telluride thin films

High-ZT materials and high-performance devices have always been hot topics in the field of thermoelectric applications. Here we present a field effect transistor (FET) based method to optimize the thermoelectric properties of bismuth telluride thin films, by which Seebeck coefficient, electrical conductivity and carrier type of the films are continuously controllable. As a result, the maximum power factor of the sample reaches 14.9 µWcm−1 K−2 in N-type and 12.5 µWcm−1 K−2 in P-type at room temperature. As compared with the bulk, the thermal conductivity of the bismuth telluride thin film is greatly reduced, which is measured to be lower than 0.37 Wm−1 K−1. The actual ZT of the sample exceeds 1.22 in N-type and 1.02 in P-type at 303 K, respectively. A π-shaped in-plane N-P pair device was built by applying different gate voltage on the bismuth telluride thin films at the two legs, which open circuit voltage is 10.5 mV and the maximum output power is 10.3 nW at a temperature difference of 30 K. By using the Te-doped bismuth telluride thin films, the intrinsic carrier concentration of the sample decreases to 1.05 × 1017/cm3 (N-type) and the films can be tuned into N-type and P-type by the opposite gate voltage symmetrically. Using this material, a thin film thermocouple with a quasi-linearly adjustable sensitivity from 2.4 to 225.5 µVK−1 by voltage was obtained. This work provides a general method to obtain high-ZT of thermoelectric materials and new ideas for fabricating performance controllable device with the same thermoelectric material, which greatly simplifies the material growth process in device manufacturing.

PH variability in catchment flows to estuaries – A South African perspective

River inflow plays an integral role on the water quality characteristics of estuaries, including pH. This study aimed to investigate pH variability in river inflow to South African estuaries and how these might be influenced by catchment characteristics. Specifically, three hypotheses were tested: 1) catchment geology is a dominant influencing factor of pH in river inflow, 2) catchment vegetation and anthropogenic pressures, e.g., urban and agriculture, act as modifiers of geology-driven ambient pH, and 3) seasonality in river flow rates can alter pH levels (e.g., pH decreasing during periods of high flow). First, drivers of pH variability were explored in relation to electrical conductivity, total alkalinity, and catchment geology type, as well as vegetation and key anthropogenic pressures. Thereafter, temporal variability was evaluated considering both inter-annual and seasonal variability also including variability in flow rates. Values of pH displayed an exponential relationship with electrical conductivity and total alkalinity, and as hypothesised pH variability was primarily influenced by catchment geology. Results also indicated that catchment vegetation (e.g., peatlands and fynbos) and/or anthropogenic pressures (e.g., urban and agriculture) act as modifiers causing pH to deviate from geology-driven ambient equilibria, especially in Table Mountain Group sandstone-dominated systems. Only limited trends in inter-annual variability were observed, mostly linked to increases in pH with increases in anthropogenic pressures. Further, a significant inverse relationship between pH and river flows was present, mostly in systems showing marked seasonality in rainfall. This study adds to our understanding of the variability of pH in river inflows to estuaries, and highlights some of the key influencing factors. Indeed, results suggest that anthropogenic pressures in catchments potentially are leading to alkalinisation of river inflow, contrary to the potential effect of ocean acidification. Finally, this study highlights the ripple effects of upstream catchment practices on downstream coastal ecosystems such as estuaries, emphasising the need for integrated catchment-to-coast management.

One-dimensional Schottky nanodiode based on telescoping polyprismanes

In the framework of the density functional theory combined with the method of non-equilibrium Green functions (DFT + NEGF), the electric transport properties of a one-dimensional nanodevice consisting of telescoping polyprismanes with various types of electrical conductivity were studied. Its transmission spectra, density of state, current-voltage characteristic, and differential conductivity are determined. It was shown that C(14,17), C(14,11), C(14,16), C(14,10) show a metallic nature, and polyprismanes C(14,5), C(14,4) possess semiconductor properties and has a band gap of 0.4 eV and 0.6 eV, respectively. It was found that, when metal C(14,11), C(14,10) and semiconductor C(14,5), C(14,4) polyprismanes are coaxially connected, a Schottky barrier is formed and a weak diode effect is observed, i.e., manifested valve (rectifying) property of telescoping polyprismanes. The enhancement of this effect occurs in the nanodevices C(14,17) – C(14,11) – C(14,5) and C(14,16) – C(14,10) – C(14,4), which have the properties of nanodiode and back nanodiode, respectively. The simulation results can be useful in creating promising active one-dimensional elements of nanoelectronics.

Протонпроводящая керамика на основе гафната и церата бария, легированных оксидами циркония, иттрия и иттербия для электролитов топливных элементов

Nanopowders of the compositions BaHf1 – xYbxO3 – δ (x = 0.04; 0.08; 0.10) and BaCe0.9 – xZrxY0.1O3 – δ (x = 0; 0.5; 0.6; 0.7 and 0.8) were synthesized by the combined crystallization and nitric acid salts using the citrate-nitrate method. Those nanopowders were used to produce ceramic materials with a cubic crystal structure of the perovskite type, with a grain size of ~ 20 – 70 nm. The study of electrophysical properties revealed that they have a proton type of conductivity in the temperature range of 500 – 700 °C; σ = 10–2 – 10–5 Cm/cm. Type and mechanism of electrical conductivity of ceramics of the composition BaHf1 – xYbxO3 – δ (x = 0.04; 0.08; 0.10) have been studied both experimentally and using theoretical calculations-by computer modeling using the electron density functional method; the results are in good agreement. The research shows the prospects of using the obtained ceramic materials as proton-conducting electrolytes of solid-oxide fuel cells.

Development of CdMnTe thin films using electroplating technique for opto-electronic device applications

Cathodic electrodeposition technique has been successfully used to achieve the growth of polycrystalline CdMnTe ternary compound thin films at different cathodic potentials. The choice of various cathodic potentials used in this work was made from the cyclic voltammogram results. The CdMnTe thin films were electroplated from electrolytes containing CdSO4, TeO2 and MnSO4·H2O in an acidic aqueous medium. The electrodeposition was carried out on glass/fluorine-doped tin oxide {FTO} substrates. The structural, optical, morphological and electrical properties of the CdMnTe thin films were studied using X-ray diffraction (XRD), UV–Vis spectroscopy, scanning electron microscopy (SEM), current–voltage (I–V) characteristics and photo-electro-chemical (PEC) cell measurements respectively. The materials investigated in this work were explored under three different conditions namely: as-deposited (AD), heat-treated ordinarily in air (HT) and heat-treated in air in the presence of CdCl2 surface treatment (CC). Results from the XRD showed that the electrodeposited films are polycrystalline with the presence of CdTexOy and CdMnTe peaks. The electroplated films have cubic crystal structures and the preferred orientation was found to be along the (111) plane. The optical energy bandgaps of the thin films were found to be deposition potential dependent. Electrical conductivity types namely p- and n-type conductivity were also obtained at different cathodic potentials using photo-electro-chemical cell measurement technique for as-deposited and heat-treated materials.

Growth characteristics of tin sulphides crystals by the vapour transport method using SnS and sulphur powders: effect of temperature and pressure

Tin sulphide compounds have two different types of 2D layered crystal structures with different electrical conduction types. Tin disulphide with n-type semiconductor characteristics has a 2D crystal structure with hexagonal symmetry, while tin monosulphide (SnS) with p-type semiconductor characteristics has a 2D crystal structure with orthorhombic symmetry. These layered materials have many potential applications such as electronic and optoelectronic devices. Meanwhile, it is known that the growth products of tin sulphides are very sensitive to the process parameters. In this study, the authors investigated the growth phenomena of tin sulphides by the vapour transport method using SnS and sulphur powders because vapour transport reactions are relatively simple and facilitate the understanding of the effects of growth parameters. The growth behaviour of tin sulphides as a function of process temperature and pressure was observed, and the results can be explained in terms of the sulphurisation and reduction of SnS powder during the growth process.

Influence of nanocellulose concentration on the tunability of energy bandgap of cadmium telluride thin films

Cadmium telluride (CdTe) doped nanocellulose thin films were successfully deposited on glass/fluorine-doped tin oxide substrates from an aqueous electrolyte bath containing hydrated cadmium sulfate (3CdSO4·8H2O) and tellurium dioxide using electrodeposition technique. Six samples of CdTe thin films were grown with nanocellulose concentrations of (0, 1, 3, 5, 7, and 9) ppm. The results obtained from electronic data of the deposited layers using UV–Vis spectrophotometer agree favourably with the theoretical formulation. The bandgap of the films ranges from 1.32 to 1.67 eV. The lowest bandgap of CdTe (1.32 eV) was achieved at a concentration of 9 ppm. This relatively low energy bandgap is remarkable in recent formation of CdTe. Photoelectrochemical cell measurement shows that the electrical conductivity type of undoped CdTe is n-type while the nanocellulose doped CdTe is p-type in electrical conduction. Hence, it is possible to effectively tune the conductive properties of CdTe by careful addition of nanocellulose concentration.

Air-Stability and Carrier Type in Conductive M3(Hexaaminobenzene)2, (M = Co, Ni, Cu).

Herein, we investigate the effects of changing the metal ions in the M-HAB system, with HAB = hexaaminobenzene ligands and M = Co, Ni, Cu. The phyiscal characteristics of this MOF family are insensitive to changes in the metal cation, which enables systematic evaluation of the effect of metal cation identity on electrical transport properties. We observe that the metal ion profoundly influences the electrical conductivity and dominant carrier type in the resulting MOF and the air-stability thereof. Cu-HAB and Co-HAB are determined to exhibit n-type conduction under both ambient and nitrogen conditions; Ni-HAB is found to be ambipolar, with its dominant carrier type dramatically affected by the environment. We examine these results through calculation of the band structure, the partial density of states, and charge transfer analysis. Unlike traditional conductive organic materials, we find that the air-stability is not well predicted by the LUMO level of these n-type MOFs but instead is additionally dependent on the occupancy and orientation of the metal ion's d-orbitals and the resulting interaction between the metal ion and ligand. This study provides fundamental insights for rational design of air-stable, electronically conductive MOFs.