Colloidal Stability Of Aqueous Suspensions Research Articles

Niobium pentoxide as an adsorbent for methylene blue removal: Synthesis, characterization and thermal stability

This study investigated the synthesis of niobium pentoxide (Nb2O5) by peroxide oxidation with hydrothermal treatment and evaluated its application for adsorption of the organic pollutant methylene blue (MB) in aqueous medium. Hydrothermal treatment was performed at 150 °C for different times (4, 12, and 24 h). The resulting materials were characterized by X-ray diffractometry, Raman spectroscopy, thermogravimetry, differential scanning calorimetry, Fourier-transform infrared spectroscopy (FTIR), N2 adsorption isotherm analysis, zeta-potential analysis, and scanning electron microscopy (SEM). Nb2O5 samples had high surface area (174 m2 g−1) and orthorhombic crystal structure. FTIR revealed that an increase in synthesis time produced an increase in surface hydroxylation. Particles dispersed in water had zeta-potential values lower than −31.3 mV, suggesting colloidal stability in aqueous suspension. SEM analyses showed no significant variation in nanoparticle morphology as a function of synthesis time. MB adsorption studies using the sample treated at 150 °C for 24 h showed that the adsorption was higher at pH 6.0, and the process follows pseudo-second order kinetics, suggesting chemical diffusion as the dominant process. The Freundlich isotherm model provided the best fit to experimental data. Thermal analyses indicated a phase transition at about 600 °C, corroborated by analysis of samples after calcination at 500 and 700 °C. Thus, the obtained materials have high specific surface area, adsorption capacity, suspension stability, and thermal stability.

Biosynthesis, Characterization, and Augmented Anticancer Activity of ZrO2 Doped ZnO/rGO Nanocomposite.

Fabrication of ZnO nanoparticles (NPs) via green process has received enormous attention for its application in biomedicine. Here, a simple and cost-effective green route is reported for the synthesis of ZrO2-doped ZnO/reduced graphene oxide nanocomposites (ZnO/ZrO2/rGO NCs) exploiting ginger rhizome extract. Our aim was to improve the anticancer performance of ZnO/ZrO2/rGO NCs without toxicity to normal cells. The preparation of pure ZnO NPs, ZnO/ZrO2 NCs, and ZnO/ZrO2/rGO NCs was confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), photoluminescence (PL), and dynamic light scattering (DLS). XRD spectra of ZnO/ZrO2/rGO NCs exhibited two distinct sets of diffraction peaks, ZnO wurtzite structure, and ZrO2 phases (monoclinic + tetragonal). The SEM and TEM data show that ZrO2-doped ZnO particles were uniformly distributed on rGO sheets with the excellent quality of lattice fringes without alterations. PL spectra intensity and particle size of ZnO decreased after ZrO2-doping and rGO addition. DLS data demonstrated that green prepared samples show excellent colloidal stability in aqueous suspension. Biological results showed that ZnO/ZrO2/rGO NCs display around 3.5-fold higher anticancer efficacy in human lung cancer (A549) and breast cancer (MCF7) cells than ZnO NPs. A mechanistic approach suggested that the anticancer response of ZnO/ZrO2/rGO NCs was mediated via oxidative stress evident by the induction of the intracellular reactive oxygen species level and the reduction of the glutathione level. Moreover, green prepared nanostructures display good cytocompatibility in normal cell lines; human lung fibroblasts (IMR90) and breast epithelial (MCF10A) cells. However, the cytocompatibility of ZnO/ZrO2/rGO NCs in normal cells was better than those of pure ZnO NPs and ZnO/ZrO2 NCs. Augmented anticancer potential and improved cytocompatibility of ZnO/ZrO2/rGO NCs was due to ginger extract mediated beneficial synergism between ZnO, ZrO2, and rGO. This novel investigation emphasizes the significance of medicinal herb mediated ZnO-based NCs synthesis for biomedical research.

Biosynthesized zinc oxide nanoparticles using seed and bark extract of Azadirachta indica for antibacterial, photocatalytic and supercapacitor applications

We have reported biosynthesis of zinc oxide (ZnO) nanoparticles (NPs: S3/B3) using an aqueous extract of seeds and barks of Azadirachta indica for antibacterial, photocatalytic, and supercapacitor applications. XRD pattern demonstrates a hexagonal wurtzite structure while FTIR spectra confirm the phytochemicals coating. Morphology is revealed from the FE-SEM images: (a) block-shaped S3 with ∼ 50–100 nm width and 90–125 nm length; (b) bar-shaped B3 with ∼ 40–50 nm thickness and 200 nm length. DLS study showed a zeta potential value of −28.93/-28.00 mV for S3/B3 indicating their good colloidal stability in aqueous suspension. Besides, antimicrobial activity of S3 is performed on various gram-negative/-positive bacteria and minimum inhibitory concentrations (MIC) are determined as 125–150 μg/mL. Moreover, methyl orange dye has been degraded with B3 NPs with a degradation efficiency of 84.62% in 180 min. Furthermore, the specific capacitance (Cs) and energy density (E) values of the S3/B3 confirmed their potentiality for supercapacitor applications.

Prolonged effects of nanodiamonds conjugated with corticosteroids

The application of detonation nanodiamonds (DNDs) in delivery systems has been demonstrated many times for a variety of substances, including anti-inflammatory drugs, antibiotics, antineoplastic agents, vitamins etc. The applicability of detonation nanodiamonds as a carrier for delivery of corticosteroids is investigated in this study. Commercial DNDs were modified to obtain particles with high colloidal stability in aqueous suspensions. Physical adsorption was then used to conjugate the DNDs with methylprednisolone sodium succinate and dexamethasone sodium phosphate. The experimental adsorption isotherms were fit with Langmuir and Freundlich adsorption models. The results of in vitro release study demonstrated an explicit prolonged effect of DNDs, due to which a sustained release of the adsorbed drugs was provided.

Stabilization of Palygorskite Aqueous Suspensions Using Bio-Based and Synthetic Polyelectrolytes.

Palygorskite is a natural fibrous clay mineral that can be used in several applications, for which colloidal stability in aqueous suspensions is a key point to improve its performance. In this study, methods of magnetic stirring, high-speed shearing, and ultrasonication, as well as different chemical dispersants, combined with these methods, namely carboxymethylcellulose, alginate, polyphosphate, and polyacrylate, were used to improve the dispersibility and the formation of stable suspensions of palygorskite in different conditions of pH. The stability and particle size of suspensions with a low concentration of palygorskite were evaluated by visual inspection, optical and electron microscopy, dynamic light scattering, and zeta potential measurements. Moreover, the palygorskite used in this work was initially characterized for its mineralogical, chemical, physical, and morphological properties. It was found that more stable suspensions were produced with ultrasonication compared to the other two physical treatments, with magnetic stirring being inefficient in all tested cases, and for higher pH values (pH of 12 and pH of 8, the natural pH of the clay) when compared to lower pH values (pH of 3). Remarkably, combined with ultrasonication, carboxymethylcellulose or in a lesser extent polyphosphate at near neutral pH allowed for the disaggregation of crystal bundles of palygorskite into individualized crystals. These results may be helpful to optimize the performance of palygorskite in several domains where it is applied.

Autofluorescence-Free In Vivo Imaging Using Polymer-Stabilized Nd3+-Doped YAG Nanocrystals.

Neodymium-doped yttrium aluminum garnet (YAG:Nd3+) has been widely developed during roughly the past 60 years and has been an outstanding fluorescent material. It has been considered as the gold standard among multipurpose solid-state lasers. Yet, the successful downsizing of this system into the nanoregimen has been elusive, so far. Indeed, the synthesis of a garnet structure at the nanoscale, with enough crystalline quality for optical applications, was found to be quite challenging. Here, we present an improved solvothermal synthesis method producing YAG:Nd3+ nanocrystals of remarkably good structural quality. Adequate surface functionalization using asymmetric double-hydrophilic block copolymers, constituted of a metal-binding block and a neutral water-soluble block, provides stabilized YAG:Nd3+ nanocrystals with long-term colloidal stability in aqueous suspensions. These newly stabilized nanoprobes offer spectroscopic quality (long lifetimes, narrow emission lines, and large Stokes shifts) close to that of bulk YAG:Nd3+. The narrow emission lines of YAG:Nd3+ nanocrystals are exploited by differential infrared fluorescence imaging, thus achieving an autofluorescence-free in vivo readout. In addition, nanothermometry measurements, based on the ratiometric fluorescence of the stabilized YAG:Nd3+ nanocrystals, are demonstrated. The progress here reported paves the way for the implementation of this new stabilized YAG:Nd3+ system in the preclinical arena.

Correlation between surface charge and hydration on mineral surfaces in aqueous solutions: A critical review

Surface charges and hydration are predominant properties of colloidal particles that govern colloidal stability in aqueous suspensions. These properties usually coexist and interact with each other. The correlation between the surface charge and hydration of minerals is summarized on the basis of innovative experimental, theoretical, and molecular dynamics simulation studies. The factors affecting the adsorption behavior of ions and water molecules, such as ion concentration, ion hydration radius and valence, and surface properties, are discussed. For example, the hydration and adsorption states completely differ between monovalent and divalent ions. For ions of the same valence, the effect of surface charge on the hydration force follows the Hofmeister adsorption series. Electrolyte concentration exerts a significant effect on the hydration force at high ion concentrations. Meanwhile, the ion correlations in high-concentration electrolyte systems become long range. The interfacial water structure largely depends on surface chemistry. The hydration layer between different surfaces shows large qualitative differences.

In English

This review analyses the authors’ recent and related works on electrokinetic properties and colloidal stability of aqueous suspension of multiwalled carbon nanotubes (CNTs) in the presence of surfactants and nanoparticles. Selected adsorptive properties of carbon nanotubes are also considered. The applicability of classical theories of electrophoresis for description of electrophoretic mobility of carbon nanotubes is discussed. Examples on the ζ-potential of CNTs in aqueous suspensions as a function of pH and concentration of electrolytes (KCl, CaCl 2 and AlCl 3 ) are given. Additions of cetyltrimethylammonium bromide (CTAB) cationic surfactant below the critical micelle formation concentration (CMC) values give a reduction and then an overcharging the CNT surface because of accumulation of the surfactant ions in the Stern layer. At concentrations above CMC the substantial drop in ζ is observed. It is due to the shift of the shear plane toward solution as a result of formation of hemi-micelles on the surface. An increase in the mass ratio of artificial mineral Laponite (Lap) in suspension (X) from 0 to 0.4 results in a monotonic decrease of the ζ-potential of CNT + Lap hybrids with reaching its plateau value ≈ –32 mV at X ≥ 0.4 that corresponds to the ζ of “pure” Lap platelets. This evidences the high surface coverage of nanotubes surface with Lap at X ≥ 0.4. The major methods to improve the dispersibility of carbon nanotubes, their colloidal stability and adsorptive properties are briefly discussed, namely: stabilization in mixtures of water and organic solvents; functionalization by chemical treatment; stabilization by additives of surfactants or polymers and hybridization by addition of supplementary stabilizing nanoparticles. CNTs can be significantly debundled in “good” solvents, such as 1-cyclohexyl-2-pyrrolidone, N,N-dimethylformamide, or N-methyl-2-pyrrolidone. It is demonstrated that the dispersibility of CNTs is a complex function of the type of surfactant, its concentration and the surfactant/CNTs ratio. The optimum concentration of CTAB to achieve homogeneous aqueous dispersion of carbon nanotubes was identified to be near the CMC. Additions of CTAB significantly modify the size distribution of CNTs and a sharp transition from small primary aggregates to large secondary aggregates at concentrations above CMC is observed. At optimal concentration of Lap the nanotube particles get well stabilized, and a stepwise increase of sedimentation stability is observed. We have shown also that CNT + Lap hybrids can be effectively used for removal of methylene blue dye from aqueous systems. The kinetics and mechanisms of adsorption are elucidated.

A simple procedure to obtain nanodiamonds from leftover of HFCVD system for biological application

Nanodiamonds (NDs) are amongst the most investigated carbon-based nanostructures due to their chemical stability and favorable mechanical properties. Despite the number of works on methods for NDs production, one of the main challenges is to achieve their colloidal stability in aqueous suspension. Additionally, NDs are normally obtained by expensive, complex and time-consuming process. Herein, it was presented a facile method to obtain NDs in aqueous suspension by using columnar structure diamond from Hot-Filament Chemical Vapour Deposition reactor (HFCVD). CVD diamond leftover thick film from CVDVale Company was used. Therefore, this method has the advantage of being not only practical but also cost-effective since it brings a profitable use of CVD diamond leftover. The Diamond thick film was submitted to ultrasonic cavitation in the presence and absence of ZrO2 microbeads in aqueous medium. The NDs hydrodynamic diameter and the stability in aqueous suspension were monitored by light scattering, size and morphology were analyzed by transmission electronic microscopy. Considering the wide application of NDs in biomedical devices, cytotoxicity of aqueous suspensions of NDs was evaluated against murine embryonic fibroblast cells. Furthermore, NDs were functionalized with hydrogen and carboxyl groups. NDs aqueous suspension of straight size distribution was obtained even in the absence of ZrO2 beads, indicating that they may be dispensable in order to decrease NDs size. NDs of average hydrodynamic diameter of 22 nm and − 35 mV of Zeta-potential were obtained after ultrasonic cavitation followed by 2 h of centrifugation, not demonstrating cytotoxicity to cells at very low (0.05–0.5 μg/mL) nor at higher concentrations (116 μg/mL). Nevertheless, NDs showed a moderate cytotoxicity at intermediary concentration range (0.5–2.2 μg/mL). From our knowledge, this is the first work that reports on a facile method for providing NDs aqueous suspension with high colloidal stability from HFCVD diamond leftover.

Colloidal Stability of Aqueous Suspensions of Polymer-Coated Iron Oxide Nanorods: Implications for Biomedical Applications

Iron oxide nanorods are considered to be very promising platforms for biomedical applications, such as magnetic hyperthermia, magnetic resonance imaging, or immunoassays based on magnetooptical effects. However, their efficient colloidal stabilization is challenging, and colloidal aggregation could lead to the total loss of their performance. This work is focused on the synthesis and colloidal stabilization of iron oxide nanorods of an average length and diameter, L × d = 31 × 6 nm, synthesized by the hydrolysis of iron(III) salt, followed by reduction of the obtained akaganeite to iron oxide in a microwave reactor. Synthesized nanorods exhibited a weak ferrimagnetic behavior with remnant magnetization MR ∼ 3 emu/g and saturation magnetization MS ∼ 13 emu/g. The nanorods were dispersed in water after adsorption on their surface of three different polymers: linear bisphosphonate–poly(ethylene glycol) (PEG) molecules (denoted as OPT), polymethacrylate backbone/PEG side chains comb polymer (denoted as PCP; w...

Disk-like nanocrystals prepared by solvolysis from regenerated cellulose and colloid properties of their hydrosols

One possible way of obtaining cellulose nanocrystals and aqueous sols with novel properties is based on modification of supramolecular structure of the polysaccharide. This modification involves rearrangements of hydrogen bonds and has an effect on polymer morphology, formation of surface reactive sites and interface interactions. Disc-like nanocrystals of cellulose II were prepared by solvolysis of regenerated cellulose in acetic acid/octanol medium in the presence of 0.4 mol% of phosphotungstic acid. The starting cellulose samples were dissolved and regenerated in the NaOH/thiourea system. Cellulose nanocrystals were studied by transmission electron microscopy, atomic force microscopy, dynamic light scattering, FTIR spectroscopy, XRD and thermogravimetric analysis. Colloidal stability of aqueous suspensions of cellulose nanocrystals in the presence of electrolyte (KCl) was studied. Their acid-base properties were revealed using potentiometric titration. The influence of electrolyte concentration on dynamic viscosity of the obtained hydrosols and their ability to show birefringence was established.

Structural, optical and X-ray attenuation properties of Tb3+:BaxCe1-xF3-x (x = 0.18-0.48) nanospheres synthesized in polyol medium.

Uniform Ba0.18Ce0.82F2.82 nanospheres have been obtained after aging a solution of barium and cerium nitrates and sodium tetrafluoroborate in a mixture of ethylene glycol and water at 120 °C for 20 hours. The diameter of the spheres could be tailored from 65 nm to 80 nm by varying the NaBF4 concentration while maintaining their colloidal stability in aqueous suspension. Increasing the aging temperature led to a phase transformation from hexagonal to cubic symmetry and to a concomitant increase of the Ba/Ce ratio, which reached a value close to the nominal one (50/50) at 240 °C. The same method was successful in obtaining Tb3+-doped nanospheres with homogeneous cation distribution and the same morphological features as the undoped material. An intense green emission was observed after the excitation of the Tb3+-doped samples through the Ce3+-Tb3+ energy transfer (ET) band. The ET efficiency increased with increasing Tb content, the maximum emission being observed for the 10% Tb-doped nanospheres. Aqueous suspensions of the latter sample showed excellent X-ray attenuation values that were superior to those of an iodine-based clinically approved contrast agent. Their fluorescence and X-ray attenuation properties make this material a potential dual bioprobe for luminescence bioimaging and X-ray computed tomography.

Layered double hydroxide using hydrothermal treatment: morphology evolution, intercalation and release kinetics of diclofenac sodium

The present work demonstrates the possibilities of hydrothermal transformation of Zn-Al layered double hydroxide (LDH) nanostructure by varying the synthetic conditions. The manipulation in washing step before hydrothermal treatment allows control over crystal morphologies, size and stability of their aqueous solutions. We examined the crystal growth process in the presence and the absence of extra ions during hydrothermal treatment and its dependence on the drug (diclofenac sodium (Dic-Na)) loading and release processes. Hexagonal plate-like crystals show sustained release with ∼90% of the drug from the matrix in a week, suggesting the applicability of LDH nanohybrids in sustained drug delivery systems. The fits to the release kinetics data indicated the drug release as a diffusion-controlled release process. LDH with rod-like morphology shows excellent colloidal stability in aqueous suspension, as studied by photon correlation spectroscopy.

Tuning Colloidal Stability of Layered Double Hydroxides: From Monovalent Ions to Polyelectrolytes.

The growing number of applications of layered double hydroxide (LDH) colloids demands for detailed understanding of particle aggregation processes in such samples. Tuning the colloidal stability in aqueous suspensions is essential to design stable systems or to induce controlled aggregation of these elongated particles. In this review, recent progress in this field is summarized; in particular, the charging and aggregation of LDHs of various compositions and sizes in the presence of different aggregating agents are discussed. The review focuses on the effect of monovalent salts, multivalent ions, and polyelectrolytes on the suspension stability of LDHs. The provided information will help to better understand the origin of interparticle forces responsible for the colloidal stability and to design highly stable or aggregating LDH colloids according to the desired goals in certain applications. Moreover, potential future research directions to obtain a broader picture of LDH aggregation are also suggested.

Surface speciation of myo-inositol hexakisphosphate adsorbed on TiO2 nanoparticles and its impact on their colloidal stability in aqueous suspension: A comparative study with orthophosphate

Despite extensive research demonstrating the influence of organic matter and inorganic phosphate on the stability of TiO2 nanoparticles (NPs), far less research has assessed the impact of myo-inositol hexakisphosphate (IHP), a common organic phosphate widely present in the environment. In this study, the adsorption of IHP on TiO2 NPs and its impact on their colloidal stability were investigated using batch experiments, dynamic light scattering (DLS) techniques, in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) and solid-state 31P nuclear magnetic resonance (NMR) spectroscopy. Inorganic orthophosphate (Pi) adsorption was run for comparison. The ratio of the Pi/IHP adsorption density (1.528: 0.453) at pH5.0 suggested that IHP may complex on the TiO2 surface through three of its six phosphate groups. Zeta potential measurements, ATR-FTIR and NMR spectra indicated that IHP/Pi adsorbed onto TiO2 NPs by forming inner-sphere complexes and modified the surface charge of these NPs, which exerted a great impact on their colloidal stability. Interactions between NPs measured by sedimentation and aggregation size highly depended on the pH, surface phosphorus coverage, and surface phosphorus species. The impact of IHP on the aggregation and dispersion of TiO2 NPs was significantly larger than that of Pi, in agreement with the calculation from the DLVO theory. This study highlighted the impact of IHP relative to Pi on the colloidal stability of TiO2 NPs in phosphorus-enriched environments.

Synthesis and preliminary in vivo evaluation of well-dispersed biomimetic nanocrystalline apatites labeled with positron emission tomographic imaging agents.

In recent years, biomimetic synthetic apatite nanoparticles (AP-NPs), having chemical similarity with the mineral phase of bone, have attracted a great interest in nanomedicine as potential drug carriers. To evaluate the therapeutic perspectives of AP-NPs through the mechanisms of action and organs they interact with, the noninvasive monitoring of their in vivo behavior is of paramount importance. To this aim, here the feasibility to radiolabel AP-NPs ("naked" and surface-modified with citrate to reduce their aggregation) with two positron emission tomographic (PET) imaging agents ([(18)F]NaF and (68)Ga-NO2AP(BP)) was investigated. [(18)F]NaF was used for the direct incorporation of the radioisotope into the crystal lattice, while the labeling by surface functionalization was accomplished by using (68)Ga-NO2AP(BP) (a new radio-metal chelating agent). The labeling results with both tracers were fast, straightforward, and reproducible. AP-NPs demonstrated excellent ability to bind relevant quantities of both radiotracers and good in vitro stability in clinically relevant media after the labeling. In vivo PET studies in healthy Wistar rats established that the radiolabeled AP-NPs gave significant PET signals and they were stable over the investigated time (90 min) since any tracer desorption was detected. These preliminary in vivo studies furthermore showed a clear ability of citrated versus naked AP-NPs to accumulate in different organs. Interestingly, contrary to naked AP-NPs, citrated ones, which unveiled higher colloidal stability in aqueous suspensions, were able to escape the first physiological filter, i.e., the lungs, being then accumulated in the liver and, to a lesser extent, in the spleen. The results of this work, along with the fact that AP-NPs can be also functionalized with targeting ligands, with therapeutic agents, and also with metals for a combination of different imaging modalities, make AP-NPs very encouraging materials for further investigations as theranostic agents in nanomedicine.

Modification and Comparative Study of Commercial Nanodiamonds

Detonation nanodiamond powders produced by different manufacturers were surface modified to reduce the amount of surface impurities and impart to the particles a high colloidal stability in aqueous suspensions. Modified DNDs (MDNDs) were separated into fractions and evaluated by the zeta potential, particles size distribution and elemental composition. MDNDs retain colloidal stability after the hydrosols are dried and the resulting powders are resuspended. Sedimentation stability and fraction composition are proposed as parameters for standardization of commercial nanodiamonds.

Tb2(bpdc)3 and Eu2(bpdc)3 Nanoparticles (bpdc: 2,2ʹ-Bipyridine-4,4ʹ- dicarboxylate) and Their Luminescence

Tb2(bpdc)3 and Eu2(bpdc)3 nanoparticles (bpdc: 2,2ʹ-bipyridine-4,4ʹ-dicarboxylate) have been prepared via straightforward precipitation from aqueous solution. The nanoparticles exhibit mean diameters of 41(5) nm (Tb2(bpdc)3) and 56(4) nm (Eu2(bpdc)3) and show a very good colloidal stability in aqueous suspension. Particle size and chemical composition have been characterized based on electron microscopy, X-ray diffraction, infrared spectroscopy and thermogravimetry. Photoluminescence validates an efficient excitation of Tb3+/Eu3+ via the bpdc ligand as an antenna that leads to intense characteristic green and red emissions. The absolute quantum yields of Tb2(bpdc)3 and Eu2(bpdc)3 have been determined at 28 and 12%, respectively. Although rare-earth metal-based photoluminescence is typically quenched in water due to vibronic loss processes (v(O-H)), here, the antenna effect and the shielding of the metal centers via the bpdc ligand are very efficient, allowing for an intense green and red emission of the Tb2(bpdc)3 and Eu2(bpdc)3 nanoparticles even in aqueous suspension.

Colloidal Stability of Aqueous Suspensions of Nano-Yttria Powders

Colloid processing of transparent yttria ceramics has been reported in this work. Aqueous suspensions of nano yttria powder were prepared by dispersing commercial powder into deionized water with triammonium citrate (TAC) as the dispersant. Effects of adsorbed dispersant, pH of suspending medium and solid loadings on the stability of the suspensions were characterized by means of sedimentation test, Zeta potential and viscosity measurements. Addition of 1.0 wt% TAC was enough to stabilize Y2O3 suspensions. The prepared colloidal suspensions with 15vol% solid loadings were subsequently consolidated into green compacts via centrifugal casting and the transmittance of the sample sintered in vacuum was measured. Ceramics prepared has an highest in line transmittance of~55% at 800 nm .  Index Terms—yttria, transparent ceramics, colloidal processing

Manufacture of YSZ-LSM Semi-Cell by Colloidal Processing

Yttria stabilized zirconia (YSZ) is the most common electrolyte in solid oxide fuel cells (SOFC). The planar configuration is widely used for designing single cells, in which a thick cathode layer can be used as the supporting electrolyte film. The manufacture of the semi-cell formed by anode and electrolyte has been widely studied and there are many works dealing with its colloidal processing. However, the semi-cell formed by cathode and electrolyte has received much lower attention. This work deals with the manufacture of a semi-cell consisting of YSZ as electrolyte and strontium-doped lanthanum manganite (LSM) as a cathode through a colloidal processing route. The colloidal behavior of diluted suspensions of YSZ and the rheology of their concentrated suspensions were studied as a function of deflocculant content, mixing time by using ultrasounds probe and ageing time. The colloidal stability of aqueous suspensions of LSM was studied by measuring the zeta potential as a function of pH and deflocculant content. These concentrated suspensions were used to obtain thick self-sustained substrates by casting methods. The YSZ electrolyte and LSM cathode were prepared by tape casting in water medium.