Sol-gel Chemical Route Research Articles

Integrated study of the structural and magnetic characteristics of Nd(Mn, Cr)0.5O3: exploring perovskite material

In this work, a perovskite material, Nd(Mn,Cr)0.5O3, is synthesized by a sol–gel chemical route method, and the structural and magnetic properties of the prepared samples were studied for a range of annealing temperatures. The variation of structural parameters against annealing temperatures is analyzed via Rietveld refinement, and it exhibits orthorhombic cubic geometry with non-monotonically increasing lattice parameters. lattice strain is due to canting in the Cr3+ and Mn3+ ions and the presence of strain is also confirmed by the shifting of XRD peaks towards a higher 2θ angle. The obtained Goldschmidt tolerance factor is 0.87, which confirms the stability of the perovskite structure. The magnetic properties of the prepared samples show the ferromagnetic transition temperature ranging from 86.5 K to 82.2 K due to super-exchange interaction between Cr3+ and Mn3+ ions via oxygen ions. The stability in crystal structure, lower value of strain, and ferromagnetic nature at low temperature for the samples annealed up to1000 °C may make this material applicable for magnetic data storage.

Green sol-gel synthesis using Moringa oleifera gum and modified structural, magnetic and optical properties of Co-Zn aluminates

The Co1-xZnxAl2O4 spinel (x = 0, 0.25, 0.5, 0.75 and 1) was synthesized using Moringa oleifera gum by the sol-gel chemical route. The characterization of the investigated samples was performed by TG-DTA, XRD, XPS, FTIR, FESEM, and VSM techniques. The XRD pattern reveals cubic spinel structure with space group Fd3̅m and a good crystallinity. Lattice parameter values linearly increase with increase in Zn concentration. The EDAX spectrum confirms purity of the prepared samples with nonexistence of the elements other than Co, Zn, Al and O. The FTIR spectrum confirms the cubic spinel structure of the aluminates. Magnetic studies showed that the saturation magnetization, as well as the coercivity of the investigated samples, is decreasing with the increasing Zn substitution. The band gap energies obtained from the UV vis absorption spectra are increasing due to phase purity and systematic variation of the lattice parameter. Moreover, the values of band gap energies suggest the possible use of the aluminates as the optical and photoluminescence materials.

Symbiotic MoO3-SrTiO3 Heterostructured Nanocatalysts for Sustainable Hydrogen Energy: Combined Experimental and Theoretical Simulations.

Highly efficient Z-scheme MoO3-SrTiO3 heterostructured nanocatalytic systems were engineered via a sol-gel chemical route and exploited in green H2 energy synthesis via overall water splitting. The optical and electronic investigations corroborated the enhancement of the optoelectronic properties of SrTiO3 after the incorporation of MoO3. Emergence of the interfacial charge transfer between SrTiO3 and MoO3 is the driving force, which synergistically triggered the catalytic efficiency of MoO3-SrTiO3 heterostructures. The substitution of Ti4+ by Mo6+ ions led to the suppression of Ti3+ mid-gap states, as the potential involved in the Mo6+/Mo5+ reduction is higher than that in Ti4+/Ti3+. Theoretical studies were employed in order to comprehend the mechanism behind the advancement in the catalytic activity of MoO3-SrTiO3 porous heterostructures, which also possessed a higher surface area. 2% MoO3-SrTiO3 exhibited the optimum catalytic response toward H2 evolution via photochemical, electrochemical, and photo-electrochemical water splitting. 2% MoO3-SrTiO3 evolved H2 at the fourfold higher rate than SrTiO3 with phenomenal 16.06% AQY during photochemical water splitting and photo-degraded MB dye at nearly 88% against the 42% degradation in SrTiO3-led photocatalysis. Electrochemical and photo-electrochemical investigations also manifested the superiority of 2% MoO3-SrTiO3 toward HER, as it exhibited accelerated current and photocurrent densities of 25.02 and 27.45 mA/cm2, respectively, at the 1 V potential. EIS studies demonstrated the improved charge separation efficiency of MoO3-SrTiO3 heterostructures. This work highlights the multi-dimensional approach of obtaining green H2 energy as the sustainable energy source using MoO3@SrTiO3 heterostructures.

Influence of Ni substitution on the magnetic properties of PrCoO3: A comprehensive study

The influence of nickel (Ni) ions on the structural and magnetic properties of PrCo1-xNixO3 perovskites was investigated. The samples were prepared using a sol-gel chemical auto-combustion route. The Rietveld refined X-ray diffraction patterns show that all samples were single-phase polycrystalline with orthorhombic (Pbnm) perovskite symmetry. Fourier transform infrared spectroscopy (FTIR) showed that with increasing Ni dopant content, the spin state changed from a low to an intermediate spin state (LS→IS), leading to an increase in the Co3+ population in the IS state, which improved the stability of the IS state. X-ray photoelectron spectroscopy confirmed the presence of mixed valence states (Co3+/Co4+) and oxygen vacancies. Ni-substituted PrCoO3 compounds exhibited mixed magnetic phases, which were separated by a theoretical model. The susceptibility curves were fitted with the Curie–Weiss law, and the negative value of the Curie–Weiss temperature indicated a strong predominance of antiferromagnetic (AFM) interactions over ferromagnetic (FM) ordering. However, when the Ni content in the host lattice increased, the FM coupling via double exchange became stronger. Thus, saturated FM ordering was achieved with an optimum doping level of Ni ions.

Electrochemical Energy Storage Properties of Sm2FeCuO6 Double Perovskite Synthesized via Sol-Gel Route

The rare Earth-based double perovskites have been widely studied due to their exceptional physical properties and wide range of technological applications. Despite the extensive investigation of copper-based rare Earth double perovskites and a limited study of samarium-based double perovskites, no reports on the synthesis and characterization of Sm2FeCuO6 have been found in the literature. This work presents the experimental investigation on the synthesis of Sm2FeCuO6 via a wet chemical sol-gel route and the characterization of its structural and electrochemical properties using various techniques. The results showed that Sm2FeCuO6 have good electrochemical properties, making it a promising candidate for use in electrochemical energy storage applications.

Rhombohedral distortion induced structural, magnetic, optical phase transitions and photocatalytic activity in Sm and Sm-Cr co-substituted bismuth ferrite nanoparticles

Rhombohedral distortion induced structural, magnetic, optical phase transitions and photocatalytic activity of BiFeO3 (BFO), samarium (Sm)-substituted and Sm-Cr co-substituted bismuth iron oxide nanoparticles were prepared using the tartaric acid modified wet chemical sol–gel route. XRD and FESEM techniques confirmed the pristine phase and nanocrystalline property of BFO, Bi0.85Sm0.15FeO3 and BSFCO5 samples. XRD as well as Raman spectra confirmed structural phase transformations from the rhombohedral (pristine BFO) to rhombohedral (Bi0.85Sm0.15FeO3 and Bi0.85Sm0.15Fe0.95Cr0.05O3), in case of Sm-Cr co-doping there is indication of more change of crystal structure than single Sm-doped. Sm-Cr co-doped into BFO could enhance magnetism, more interestingly; M−H loops reveal the highest saturation magnetization value compared to Sm-doped and BFO. An obvious blue shift is noted in the substituted samples as well as the reduction of bandgap compared to pristine BFO. The co-substitution enhanced the photocatalytic degradation activity as compared to Sm-doped and pure BiFeO3.

Tuning of structural, electrical and transport behaviour of cobalt nanoferrite by dysprosium ions substitution

Present study explores the structural, electrical and transport properties of dysprosium cation (Dy3+) substitution on (Fe+3) site in cobalt nonoferrites [CoFe2-xDyxO4 (Dy(x) = 0.00, 0.05, 0.10 & 0.15)] prepared by sol-gel chemical route. X-ray diffraction pattern confirms the pure cubic spinel structure for all samples. The average crystallite size was found in the range of 49 to 72 nm with no linear variation with incresing doping concentration of (Dy3+) ions. The values of lattice parametres is found to be changed from 8.34 to 8.39 Å for pristine cobalt nanoferrite (CoFe2O4) and sample having highest doping concentration i.e. Dy(x) = 0.15 respectively. The porosity observed to be decrease linearly with increasing (Dy3+) ion concentration. The electrical properties have been investigated by analyzing dielectric behaviour in the frequency range of 75 kHz- 5 MHz and temperature range of 100K– 400K. The frequency dependent dielectric behaviour at different temperatures is explained in terms of Maxwell–Wagner and Koop’s phenomenological models. Ferrite with Dy(x) = 0.15 have achieved highest dielectric constant in the range of 441 to 5234 which was measured at 100K (5 MHz) and 400K (75 kHz) respectively. The electrical resistivity of each of the ferrite sample reduces with rising temperature representing the semiconductor behaviour of all ferrites which is due to the thermally triggered charge carriers hopping between (Fe2+) and (Fe3+) ions and associated with higher drift mobility. The increase in drift mobility at room temperature with increasing (Dy3+) ion concentration is considered to be a sign of improved transport behaviour. The high value of dielectric constant and low dielectric loss of all these ferrites make them suitable for the memory storage devices.

Room temperature multiferroicity of hexagonal LuFeO3 and its enhancement by co-doping in Lu0.9Co0.1Fe0.9Ti0.1O3 nanoparticle system

Antiferromagnetic LuFeO3 can be good multiferroic by having ferroelectricity in its non-centrosymmetric hexagonal phase. But, it is hard to stabilize this metastable phase, preventing the stable orthorhombic phase. In this work, metastable hexagonal LuFeO3 (LFO) nanoparticle was stabilized in chemical sol-gel route in pure phase and co-doped with Co and Ti in the same route to synthesize Lu0.9Co0.1Fe0.9Ti0.1O3 (LCFTO) nanoparticles. Room temperature multiferroicity of bare LFO was established through relevant characterization. And motive behind the co-doping is to enhance the magnetoelectric behavior of the bare system to synthesize a new monophasic type II magnetoelectric multiferroic. Structural investigation by thorough Rietveld analyses of the recorded X-ray diffractograms, confirmed the formation of pure hexagonal (P63cm) phase of both bare and doped LFO. However, deviations in various structural & microstructural parameters were observed in the doped system, which is mainly responsible for the enhancement of magnetic and electric properties of the sample. Presence of antiferromagnetic transition at ∼604 K confirmed the room temperature magnetic ordering of bare LFO. Interestingly, LCFTO shows a drastic enhancement of magnetic property than the bare one in all concerns, where the maximum magnetization at the maximum applied field is enhanced by nearly 36 times at room temperature. Detailed high-temperature dielectric investigation shows, good dielectric strength (∼261) of LFO gets enhanced highly in LCFTO (∼1053) and a high relaxation time having negligible loss factor with an indication of ferro to paraelectric transition above room temperature. Current density vs. electric field (J-E) curve suggests the presence of polarization at room temperature with negligible leakage loss. Direct measurement of ferroelectric loop shows the ferroelectricity (Pmax∼0.064 µc/cm2) of bare LFO at room temperature and a well improvement in the doped LCFTO (Pmax∼0.151 µc/cm2). The presence of room temperature magnetoelectric coupling, confirmed by magnetocapacitance measurements, results in a high value (∼5 %) of magnetocapacitance in the doped system which is also much higher than the bare one (<∼1 %) as expected. All these properties confirm the magnetoelectric multiferroicity of bare h-LuFeO3 at room temperature. And, co-doping in hexagonal LuFeO3 nanoparticle system results in a considerable improvement in its magnetoelectric behavior, so this co-doped system can be a promising and potential magnetoelectric multiferroic for the future generation magnetoelectric devices.

Magnetic, magnetocaloric and critical exponent properties of Eu3(PO4)2 prepared by sol gel method

The Eu3(PO4)2 compound was prepared by the sol gel chemical route and its magnetic, magnetocaloric, and critical exponent properties have been investigated. Combining different models, a detailed analysis of the magnetic phase transitions in the Eu3(PO4)2 compound has been actually performed. At 5.9 K, the phase transition from the AFM (Antiferromagnetic) state to the PM (Paramagnetic) state is 2nd order. A phenomenological model is now used to comprehend the MCE (magnetocaloric effect) behavior of this sample. The CEs (Critical Exponents) are clearly obtained employing MAPs (Modified-Arrott-Plots), CIA (Critical Isotherm Analysis) and also WSR (Windom Scaling Relation) techniques based upon the data of magnetic measurements registered around the TN (Néel temperature). Besides, an analysis of critical performance on the basis of the MCE is also provided. These exponents are β (beta), γ (gamma), and δ (delta) were properly revealed to be nearby those of the MFM (Mean-Field-Model) values. This simply reflects the existence of an AFM long-range order in our sample. A single equation of state also can be used to scale the magnetization below and above TN. Nevertheless, it should be noted that the scaling relations are respected, which indicates a renormalization of the interactions nearby the TN. The forecasting of the J(r) (exchange interaction) validated the long-range AFM order in this sample.

Frequency and temperature dependent electrical characteristics of NBT based ceramics prepared by Sol-gel method

The preparation of the individual powders for the sodium bismuth titanate-based composites 0.90NBT + 0.10ST and 0.90NBT + 0.10CT (where NBT = Na0.5Bi0.5TiO3, ST = SrTiO3, and CT = CaTiO3) takes place through a solid state reaction process. Where individual powders are prepared with Sol gel chemical route. Studies using XRD and SEM confirm the formation of composites. Microstructure of the composites shows large grains. Temperature-dependent studies of dielectric and PE loops are conducted. The relative density, grain size, and ST concentration influenced the polarization properties of the specimens. The phase transition in NBT is associated with changes in alignment of dipoles into micropolar regions. For NBCT composite, the ferroelectric and polarization properties are degenerated. Activation energy of the composites was calculated using dielectric parameters.

Structural, Dielectric and Electrical Properties of Homovalent Doped SrSn1-xTixO3 (0 ≤ x ≤ 0.08) System

The samples SrSn1-xTixO3 with composition 0≤x≤0.08 have been prepared using sol-gel chemical route by sintering at 1173 K. All the samples are found to be single phase crystallized in orthorhombic structure. The dielectric properties indicate the existence of interfacial and orientation polarization in samples found to be stable up to 300 oC. Thermal dependence of electrical conductivity represents two conduction regions with activation energy (0.77-0.94) eV in region-1 and (0.19-0.27) eV in region-2 respectively. The plot of dc conductivity with hopping frequency results unit slope representing that the charge carriers remain same in both processes. DC conductivity of samples are found to be increased with Ti4+, due to reduction in polaron size. The present materials can be potentially used in thermally stable capacitor and mixed ionic and electronic conductors (MIECs) applications.

Ion exchange behavior of novel Pani -Ti(IV) phosphosulphosalicylate hybrid cation exchange material for the selective separation of Pb(II) in environmental remediation

ABSTRACT A new hybrid cation exchange material PANI-Ti(IV) phosphosulphosalicylate was synthesized by intercalating polyaniline (PANI) into Ti(IV) phosphosulphosalicylate (Ti(IV) PSS) using sol-gel chemical route. Then, it is renewed into H+ form and used as an adsorbent for the removal of Pb(II) from aqueous solution. The morphology and structure properties of the as prepared hybrid cation exchange material were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET), thermo gravimetric analysis (TGA-DTG), and Transmission Electron Microscopy (TEM). The sorption experiment for Pb(II) removal was performed using batch method. Dependence of adsorption on contact time, exchanger dose, Pb(II) initial concentration, pH, and temperature has been studied to achieve the optimum conditions. The adsorption isotherm, kinetics, and thermodynamics of PTPSS for Pb(II) were studied. The results of the above mentioned analyses show that the adsorption isotherm process of Pb(II) on PTPSS was closely related to Langmuir model (r2 > 0.998). The adsorption kinetic process fits well with the pseudo-second order equation. Thermodynamic studies suggested the spontaneous and exothermic nature of PTPSS system. The ion exchange adsorbent shows ion exchange capacity for Li+, Na+, and K+ ions have been found to be 1.75, 2.24, and 2.41 meq/g, respectively. Its selectivity was examined by achieving some important binary separations like Pb2+- Cd2+, Pb2+- Hg2+, Pb2+- Cu2+, Pb2+- Zn2+, Pb2+- Ni2+, and Pb2+- Fe3+ on its column. On the basis of distribution studies (Kd values), PTPSS was highly selective for Pb(II). Therefore, the hybrid cation exchange material PTPSS can be used as a potential ion exchange material for the selective separation of Pb(II) ion in environmental remediation.

Sintering Temperature Driven Structural, Dielectric, Ferroelectric, and Piezoelectric Properties of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 Lead-Free Composites

Lead-free 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 composites have been synthesized via sol-gel chemical route. We have systematically investigated the influence of sintering temperature on the structural and electrical properties of the BZT-BCT composites. The 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 composites were prepared by combining Ba(Zr0.2Ti0.8)O3 (BZT) and (Ba0.7Ca0.3)TiO3 (BCT) powders and sintered at different temperatures 900-14000C. The electrical properties of BZT-BCT composites improve with increasing sintering temperature. The composites sintered at 1300 and 14000C exhibit enhanced ferroelectric properties with spontaneous polarization Ps ~ 11.2 μC/cm2 and 8.66 μC/cm2 respectively. The dielectric and piezoelectric properties of BZT-BCT composites also improve with increasing sintering temperature. The dielectric constant value εʹ ~ 2938, tan δ ~ 0.016 and piezoelectric co-efficient d33 ~ 278 pC/N were measured for BZT-BCT composite sintered at 14000C while observing a considerably high transition temperature of Tc ~ 1200C. The observed results are discussed in terms of structural and microstructural analysis as a function of sintering temperature.

Silver-Doped BaSrTiO₃ Nanocomposite: Synthesis, Characterization, Antibacterial and Photocatalytic Activities.

In this research, strontium titanate (SrTiO₃), barium titanate (BaTiO₃), barium strontium titanate (BaSrTiO₃), and Ag-doped BaSrTiO₃ nanocomposites with different Ag contents were fabricated using the sol-gel chemical route. The prepared samples were characterized by several techniques including scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), differential reflectance spectroscopy (DRS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma spectroscopy (ICP), and Brunauer-Emmett-Teller (BET) measurement. The EDS results indicated that the synthesized nanoparticles had a cube perovskite-like structure. The EDS and ICP results revealed that Ag was doped into the Ba0.5Sr0.5TiO₃ structure. The SEM and TEM images demonstrated that the particle size of 15 mol% Ag-doped Ba0.5Sr0.5TiO₃ was smaller than that of pure Ba0.5Sr0.5TiO₃ as confirmed by surface area results. The photocatalytic properties of undoped titanate samples and Ag-doped Ba0.5Sr0.5TiO₃ were studied by the photodecomposition of Eosin yellowish (EY) and methylene blue (MB) dyes. The results illustrated that the photodegradation efficiency of the Ag-doped Ba0.5Sr0.5TiO₃ was far higher than the undoped titanate sample, and the optimum Ag doping was 15 mol%. The antibacterial activities of pure Ba0.5Sr0.5TiO₃ and Ag-doped Ba0.5Sr0.5Ti0₃ were studied against Staphylococcus aureus as Gram-positive (+) and Pseudomonas aeruginosa and Escherichia coli as Gram-negative (-) bacteria. In comparison with the bare Ba0.5Sr0.5TiO₃ nanoparticles, the Ag-doped sample showed a significant enhancement in antibacterial activities against both Gram-negative and Gram-positive bacterial strains.

Eg[formula omitted]t2g Sub band splitting via crystal field and band anticrossing interaction in NixCd1-xO thin films

In the present work, full composition range of NixCd1-xO thin films, from Cadmium oxide to Nickel oxide are prepared with sol-gel chemical synthesis route on corning glass substrates. The Fourier transform infrared spectra provide a direct indication of compositional dependence for different vibrational modes with increasing Ni doping. The microscopy images reflect the reduced crystallinity and closely packed morphology with increasing Ni doping which endorses the changes reflected in electronic structure. The O K edge, soft X-ray absorption spectra (XAS) for thin films indicate a clear evidence of eg and t2g sub band splitting and has been explained via crystal field splitting and three level band anti-crossing (BAC) interaction phenomena. At higher doping fraction, the inhomogeneous electric field of neighboring ions surrounding the unfilled Ni 3d level results in rupturing of L−S coupling and further crystal field splitting. The BAC interaction brings about partially unoccupied localized Ni 3d and empty d acceptor levels above conduction band minima (CBM). As saturated Fermi level goes below CBM with increasing Ni doping, transitions to antibonding orbital [eg(π*) and t2g(σ*)] with finite energy difference, is reflected as separated eg-t2g peaks in XAS spectra. On the other hand, extended X-ray absorption fine structure for Ni K edge fitting provides a complete information for nearest (Ni-O) and next nearest (Ni-Ni) neighbor bond length.

Structural, optical and electrical properties of Mn-doped ZnFe2O4 synthesized using sol–gel method

The system Zn1-xMnxFe2O4 (x = 0, 2, and 4%) was prepared by sol–gel chemical route at 80 °C. X-Ray powder diffraction and Raman spectrum analysis were used to determine the preliminary phase of obtained samples. W–H and SSP plots were used to determine the crystallite size and micro-strain of samples. The surface charge and morphology of the samples were studied using zeta potential and scanning electron microscope analysis, respectively. The optical bandgap of the samples suggested that they were semiconducting. The dielectric characteristics of samples were examined as a function of temperature (60–600 °C) at various frequencies (1 kHz, 10 kHz, 100 kHz, and 1 MHz). The presence of interfacial and orientational polarization was indicated by dielectric constant and dissipation factor studies, which ranged from (0.7–460) to (0.3–0.8) with Mn and were found thermally stable up to 300 °C. The thermal dependence of DC conductivity demonstrates Arrhenius type transport with one, two, and three regions of conduction in sample ZF-0, ZF-2, and ZF-4 respectively. The sources of charge carriers in samples were $${V}_{o}^{\cdot \cdot }$$ , $$e^{\prime}$$ and dipole defects $$\left( {V_{o}^{{ \cdot \cdot }} - 2{Fe_{{Fe^{{3 + }} }}^{{2 + }}} ^{\prime } } \right)$$ / $$\left( {{2Mn^{{3 + }} _{Zn^{{2 + }} }}^.- 2{Fe_{{Fe^{{3 + }} }}^{{2 + }}} ^{\prime } } \right)$$ . The current work could help to identify the possible applications in semiconductor devices, thermally stable capacitors, and as mixed ionic electronic conductors in solid oxide fuel cells.

Synthesis of novel PANI-based Ti(IV) phosphosulphosalicylate composite cation exchanger — structural, electrical, and impedance properties

In order to combine the properties of inorganic ion exchanger and conducting organic polymer, a new class of organic–inorganic composite cation exchanger PANI–Ti(IV) phosphosulphosalicylate (PTPSS) was synthesized by intercalating polyaniline (PANI) into Ti(IV) phosphosulphosalicylate (Ti(IV) PSS) using sol–gel chemical route with enhanced properties. PTPSS has been characterized by using Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray (EDAX), thermo gravimetric analysis (TGA-DTG), and Transmission Electron Microscopy (TEM). Ac electrical conductivity studies were also performed. This material possessed electrical conductivity of [Formula: see text] – [Formula: see text] [Formula: see text]which falls in the semiconducting range. The frequency (2 × 105– 1 × 106Hz) dependent Ac conductivity at room temperature suggests the evidence for the transport mechanism for the conductivity in PTPSS. The structure of the composite cation exchanger extremely supports its conducting behavior.

Structural, microstructure, optical, and electrical properties of Ti-doped CaSnO3 prepared by Sol-Gel chemical route

This paper discusses the structural, microstructure, optical and electrical properties of perovskite CaSnO3 modified by Ti doping. Single phase of Ti-doped CaSnO3 was obtained using sol-gel method followed by calcination at 750 °C. X-ray diffraction and Fourier transform infrared spectroscopy techniques were used to probe Ti in the samples. Value of lattice parameters of all samples obtained from Rietveld refinement initially decreases with Ti-doping up to CSO5 and then slight increases for CSO7, due to difference in ionic radius between Ti4+ (0.61 Å) and Sn4+ (0.69 Å) and surface defect respectively. Using SEM, an average grain size of sintered samples was determined in the range of (0.38–1.02) μm. Because of the presence of dipole at large distances, the dielectric constant and tangent loss of samples was found to be independent of temperatures up to 300 °C, making it a potential candidate for thermally stable capacitor application. Nevertheless, the Arrhenius type conduction mechanism was found to be active in all samples with activation energy (0.41–0.68) eV, indicated that the conduction in samples occurred by transferring electrons between degenerate sites of Sn (Sn4+/Sn3+/Sn2+) and Ti (Ti4+/Ti3+/Ti2+). The P-E loop of CSO5 sample shows higher saturation polarization and coercive field than CSO0, making it a potential candidate for memory device application.

Novel MgHf4P6O24 as a Solid Electrolyte in Mg-Sensors

In this study, a modified sol-gel chemical route was developed for synthesising MgHf4P6O24 multicomponent nanostructured ceramic oxide electrolytes. The chemical synthesis approach was determined by substituting the Zr4+ B-site in MgZr4P6O24 solid electrolyte [1-3] with Hf4+ reactive oxide, resulting in a considerably low activation energy (Ea = 0.74 ± 0.04 eV) and a promising ionic conductivity (4.52 x 10-4 Scm-1 at 747oC), for the novel MgHf4P6O24 solid electrolyte.The solid electrolyte was first calcined at a relatively low temperature range of 800-900oC, while the resultant calcined nanopowders were pressed into pellets of 13mm diameter (Ø) and 3.8mm thickness using a uniaxial steel press at 5kN compressive pressure. The pressed pellets were later sintered at 1000 ≤ T/oC ≤ 1550 temperature range. Meanwhile, calcination and sintering temperatures of the electroceramic electrolytes were maintained at 900 ≤ T/oC ≤ 1300oC after TGA-DSC thermal analysis and densification measurements; An optimum density and stable thermodynamic composition of the solid oxide pellets were also achieved at 1300oC. X-ray diffraction and rietveld analysis reveals a good crystallinity of the solid electrolyte with an average crystallite size of 20±2 nm and 42±2 nm at 800oC and 900oC, respectively, this indicates that crystallite size increases as a function of calcination temperature, which is consistent with the TGA-DSC thermal analysis profiles and confirmed using HRTEM. Interestingly, the refined crystallographic data and conductivity properties of the novel MgHf4P6O24 solid electrolyte characterised in this study was reported for the first time. The MgHf4P6O24 solid electrolyte characterised for their electrical and thermodynamic properties portray reliable ionic and transport properties of the solid electrolyte; The average transport number for Mg2+-cations in MgHf4P6O24 solid electrolyte measured as a function of Mg concentration in molten Al is 0.84±0.03. Ionic conductivity and thermodynamic stability of the solid electrolyte in this study was compared to those of MgZr4P6O24 electrolyte [1, 3], which shows novel improvement in the ionic conductivity and thermodynamic properties of both solid oxide electrolytes.Relying on the structural, thermodynamic stability and ionic conductivity data in this study, Mg-sensor probes were designed and fabricated, then tested in molten Al at 700±5oC, using the electrochemical method illustrated in Figure 1[3]. In application, a high-temperature Mg-sensor probe was fabricated using the Mg2+-cation conductors characterised in this study by incorporating a biphasic powder mixture of MgCr2O4+Cr2O3 ceramic reference electrode in air, showing promising trend after successfully sensing Mg dissolved in molten Al alloys at 700±5oC. A linear dependence of sensor voltage on the logarithm of Mg concentration was obtained. The thermodynamic activity of Mg in molten Al shows a rather negative deviation from Raoult's law [4]. MgHf4P6O24 solid electrolyte has useful potential applications in high-temperature Mg-sensors during refining, virgin metals alloying and scrap metal recycling for improved environmental sustainability and climate change. Figure 1. A schematic of high-temperature Mg-sensor test rig [3].

AC-conduction mechanism via dielectric measurements of (Cr)x/(CuTl)-1223 nanoparticles-superconductor composites

Chemical sol-gel route was opted for synthesis of chromium (Cr) nanoparticles (NPs) and solid-state reaction method was used to synthesize the superconducting (CuTl)0.5Ba2Ca2Cu3O10-δ {(CuTl)-1223} phase. The desired (Cr)x/(CuTl)-1223; x = 0–2.0 wt% nanoparticles-superconductor composites were obtained by the incorporation of Cr NPs in the host superconducting (CuTl)-1223 matrix. The crystal structure along with the phase purity was explored by X-rays diffraction (XRD) and the transport properties were studied by the dc-resistivity and dielectric measurements of these composites. The crystal structure of these composites was found un-altered, which indicated the presence of Cr NPs at the inter-granular regions of the host CuTl-1223 superconducting matrix. The suppression in superconducting transport properties of CuTl-1223 superconducting phase could be associated to the reduction of superconducting volume fraction after the inclusion of Cr NPs. The effects of Cr NPs on the ac-conduction process in (CuTl)-1223 phase were investigated via frequency dependent dielectric measurements at different operating temperatures.