Source Of Force Research Articles

Influence of ionic cerium and cerium oxide nanoparticles on Zea mays seedlings grown with and without cadmium

Cerium (Ce4+) and cerium oxide nanoparticles (CeO2-NPs) have diversified reported effects on plants. Once dispersed in the environment their fate is not well understood, especially in co-existence with other pollutants like cadmium (Cd). The effect of co-application of Ce and Cd are reported in various studies, but the role of Ce source (ionic or bulk) and nanoparticle size is still unknown in cereal plants like maize (Zea mays). To better understand the synergistic effects of Ce and Cd, 500 mg kg−1 Ce coming from ionic (Ce4+ as CeSO4) and CeO2 nano sources (10 nm, 50 nm, and 100 nm) alone and in combination with 0.5 mg Cd kg−1 sand were applied to maize seedlings. Growth, physiology, root structure, anatomy, and ionic homeostasis in maize were measured. The results revealed that Ce4+ resulted in overall decrease in seedling growth, biomass and resulted in higher heavy metal (in control sets) and Cd (in Cd spiked sets) uptake in maize seedlings' root and shoot. The effects of CeO2-NPs were found to be dependent on particle size; in fact, under Cd-0 (non-Cd spiked sets) CeO2-100 nm showed beneficial effects compared to the control. While under co-application with Cd, CeO2-50 nm showed net beneficial effects on maize seedling growth parameters. The Ce alone, and in combination with Cd, altered the root suberin barrier formation. Both ionic and nano Ce sources alone and in co-existence with Cd behaved differently for tissue elemental concentrations (Ce, Cd, micronutrients like B, Mn, Ni, Cu, Zn, Mo, Fe and elements Co, Si) suggesting a strong influence of Cd–Ce coexistence on the element's uptake and translocation in maize.

Reanalyzing Mandarin V1-V2resultative constructions—A force-theoretic approach

AbstractThis study takes a force-theoretic approach to Mandarin V1-V2resultative constructions. Unlike event-based analyses that hold a causing event accountable for a result state, this study attributes a result state to a specific entity involved in the relevant causing event. In this way, V1-V2resultative construction (RC) sentences have the interpretation that through a causing action, one entity relevant to the action caused a change of state to another entity; this causal influence is reconceptualized as a force from the former entity, characterizing the situation change concerning the latter entity. Following Copley and Harley (2015), this conceptual reanalysis is represented structurally, successfully deriving V1-V2RC sentences. V2and the internal argument DP specify the property of a resultant situation and its holder, defining the force; the external argument DP tells about this force's source; V1modifies this force, indicating the causing action through which this force is realized.

Hierarchical structured nano-polyhedrons of CeO2@ZIF-8 composite for high performance supercapacitor applications

A well-organized composites based on crustal abundance rare earth metal were developed as the potential electrode for high-performance supercapacitors. The new category of hierarchical nano-polyhedrons of cerium (Ce) doped ZIF-8 composite electrodes were prepared through wet-chemical strategy by varying the concentrations of Ce precursors and determined for their plausible applications in supercapacitors. The XRD and SEM results revealed the structural stability and morphological activity of the prepared composites and then investigated overall energy storage performance. The synthesized composite electrode of Ce-MOF-0.5 using 0.5 mM Ce source with ZIF-8 framework delivered the maximum capacitance of 424.2 F.g−1 by the three-electrode measurement. The optimized Ce-MOF-0.5 electrode incorporated symmetric supercapacitor cell offered an excellent capacitive behavior with the capacitance 132 F.g−1 @ 1 A.g−1, and the device retains the 90% of capacitance upon 5000 cycles during charging-discharging cycles. Further, asymmetric supercapacitor device performance has been assessed and the device delivers high capacitance (89 F.g−1 @ 1 A.g−1), higher energy density (31.3 W.h.kg−1 @ 800 W.kg−1) and indicating higher electrochemical performance of the Ce-MOF-0.5//AC device.

Adsorption and Desorption Properties of CO2 on CeO2 Nanoparticles Prepared via Different Synthetic Routes

The reversible adsorption and desorption of CO2 was investigated in the temperature range between room temperature and 250°C on the CeO2 powders prepared through different synthetic routes. The adsorption of CO2 was evaluated with respect to the weight change in the thermogravimetric analysis. Each CeO2 powder was composed of well-crystallized nanometer-sized grains independent of the synthetic routes. The specific surface area varied with the synthetic route, while it was not only the parameter determining the CO2 adsorption. It was found that the crystallite size grown to some extent, or crystallinity, was advantageous for the CO2 adsorption. In addition, the CeO2 powders prepared from a Ce(III) source through the pyrolysis of the precursors containing carbonate groups tended to enhance the CO2 adsorption. The highest value of the CO2 adsorption was 0.051 g per 1 g of CeO2. The surface coverage for the sample, evaluated with {adsorbed CO2 molecules} × {adsorption cross section of CO2}/{specific surface area of the CeO2 sample determined with N2 adsorption}, reached 1.02, which corresponded to a situation that the surface was fully covered with CO2 molecules.

Comparative study of acid-basic properties of MCF impregnated with niobium and cerium species

Niobium and cerium dopants of mesoporous cellular foams, MCF, have been recently considered as promoters enhancing the basicity of amino-organosilanes anchored to the supports. Thus, the knowledge of acid-basic properties of niobium and cerium containing MCFs is important. Therefore, in this work monometallic (Ce and Nb) and bimetallic (Ce + Nb) materials based on MCF were investigated by means of NO and pyridine adsorption combined with infrared (FTIR) and electron spin resonance (ESR) spectroscopies as well as test reactions. The properties of bimetallic materials strongly depended on the method of impregnation (one-pot vs. step-by-step procedure). If niobium was included in step-by-step method (first niobium and next cerium sources – Ce/Nb/MCF) the Nb species were incorporated to silica skeleton and ceria surrounded some of the framework niobium species (NbO−) enhancing the acidic strength of tetra-coordinated niobium cations playing the role of Lewis acid sites (LAS). One-pot modification (simultaneous impregnation with Nb and Ce sources – CeNb/MCF) resulted in the formation of niobium and cerium oxides showing synergistic interaction. In this system ceria was more defected than in Ce/Nb/MCF sample and acidic strength of niobium species (LAS) was lower.

Highly sensitive DNA sensors based on cerium oxide nanorods

In this work, a CeO2 nanorod (NR)-based electrochemical DNA sensor was developed to identify Salmonella that causes food-borne infections. CeO2 NRs were synthesized without templates via a simple and unexpensive hydrothermal approach at 170 °C for 12 h by using CeO(NO3)3·6H2O as a Ce source. The DNA probe was immobilized onto the CeO2 NR-modified electrode through covalent attachment. The characteristics of the hybridized DNA were analyzed through electrochemical impedance spectroscopy (EIS) with [Fe(CN)6]3−/4− as a redox probe. Experimental results showed that electron transfer resistance (Ret) increased after the DNA probe was attached to the electrode surface and increased further after the DNA probe hybridized with its complementary sequence. A linear response of Ret to the target DNA concentration was found from 0.01 μM to 2 μM. The detection limit and sensitivity of the DNA sensor were 0.01 μM and 3362.1 Ω μM−1 cm−2, respectively. Various parameters, such as pH value, ionic strength, DNA probe concentration, and hybridization time, influencing DNA sensor responses were also investigated.

Thermal decomposition synthesis, characterization and electrochemical hydrogen storage characteristics of Co3O4–CeO2 porous nanocomposite

Particle-like Co3O4–CeO2 nanocomposite was synthesized via a facile thermal decomposition process in the presence of fructose as a green capping agent and ammonium cerium(IV) nitrate as Ce source. The effect of various parameters such as different cobalt sources, calcination temperature and time were investigated on the size and morphology of products. The transmission electron microscopy observations indicated that the synthesized products have a particle-like shape with an average diameter of 18–35 nm. For the first time, the electrochemical hydrogen storage performance of Co3O4–CeO2 porous nanocomposite was investigated via chronopotentiometry method in aqueous KOH solution in this paper. The electrochemical measurements showed that this product has a good hydrogen storage capacity at room temperature. Its maximum discharge capacity was 5200 mAh/g after 20 cycles. Therefore, Co3O4–CeO2 porous nanocomposite showed that it is a good candidate for electrochemical hydrogen storage.

Behavior of La0.6sr 0.4Co0.2Fe0.2O3-δ Cathode Powders Surface Modified by Atomic Layer Deposition for Solid Oxide Fuel Cells

Atomic layer deposition (ALD) has been used to modify the surfaces of La0.6Sr0.4Co0.2Fe0.2O3- d (LSCF) cathode powders with gadolinium doped ceria (GDC) and cobalt doped zirconia (CDZ). Cyclopentadienyl based Gd and Ce sources were used for GDC, while amidinate and amide sources were used for Co and Zr, respectively. ALD was carried out between 240-260°C. Transmission electron microscopy indicated uniform coating on selected samples, depending on process recipe. Coated powders were pressed into pellets and sintered at 1000°C in air. Microstructural analysis by scanning electron microscopy (SEM) revealed good sintering behavior. Similar sintering was observed for both GDC and CDZ treated powders. Pycnometry showed porosities in the range of approximately 41% for uncoated LSCF and in the range of 37-39% for surface modified powders and mercury probe analysis showed similar pore size distributions. Symmetrical electrochemical cells were prepared from pastes of uncoated and surface modified powders using a scandium stabilized zirconia electrolyte. Electrical impedance spectroscopy showed marked improvements in polarization for the surface modified powders (Fig. 1). ZrO2 and GDC coatings decreased polarization by a factor of 2. CDZ coatings decreased polarization by a factor of up to 4. Equivalent circuit modeling suggested little effect on gas diffusion through the porous structure, consistent with similar porosity values. Intermediate and high frequency contributions were significantly affected, suggesting a strong positive impact of the surface modification on both non-charge-transfer properties and charge-transfer properties, respectively. A pre-fabricated symmetrical cell treated with GDC via ALD showed very similar behavior to a symmetrical cell fabricated from surface modified GDC. This suggests that ALD may be used in alternate ways to improve cathode performance: on a fully sintered cathode or on the powder prior to sintering. Figure 1

Photocatalytic performances and characterizations of sea urchin-like N,Ce codoped TiO2 photocatalyst

We prepared sea urhcin-like N, Ce codoped TiO2 using a solvothermal method to reduce the recombination rate of photo-induced electron–hole pairs and improve sunlight utilization. Carbamide and cerium (III) nitrate hexahydrate served as the N and Ce sources, respectively. The prepared N-, Ce-codoped TiO2 with different content was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectra (XPS) and diffuse reflectance UV–vis spectroscopy. Results showed that the crystal phase of N-, Ce-codoped TiO2 samples contained both rutile and anatase phases. The XPS of N and Ce showed the appearance of Ce4+ and N1s. Meanwhile, the photocatalytic efficiency of prepared samples was investigated by the degradation of Rhodamine B under sunlight irradiation. In addition, the proposed excited electron transfer mechanism of organic dye Rhodamine B degradation has also been discussed.

Corrosion protection of carbon steel by silica-based hybrid coatings containing cerium salts: Effect of silica nanoparticle content

One strategy for minimising corrosive attack on carbon steel involves the application of hybrid coatings rich in rare earths, on the basis of their low toxicity and environmental sustainability. Tetraethoxysilane (TEOS) and 3-glycidoxypropyl-trimethoxysilane (GPTMS) were each used here as precursors, together with various quantities of colloidal silica suspension, to improve barrier properties of the coatings. Ce(NO3)3·6H2O was added as a source of Ce(III) for further inhibition of corrosion. The corrosion resistance of each kind of sample was evaluated using potentiodynamic polarisation measurements and electrochemical impedance spectroscopy (EIS) in 0.35wt.% NaCl solution. The electrochemical behaviour at various immersion times was modelled by equivalent circuits to demonstrate the effect of silica nanoparticle loading on corrosion. Additional testing was performed under harsh conditions of salt spray chamber. The microstructure and composition of sol–gel coatings were characterised by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS), focused-ion beam SEM/EDS analysis, X-ray photoelectron spectroscopy and confocal microscopy.

Shape-Controlled CeO<sub>2</sub> Nanomaterials Prepared by Hydrothermal Process

A simple hydrothermal method was developed to prepare shaped-controlled CeO2 nanomaterials, in which, Ce (NO3)3· 6H2O was used as Ce source and H2O2 was used as oxidant and morphologies controlling agent. Different morphologies of CeO2 including nanoparticles, nanooctahedrons, nanorods and nanocubes could be obtained by simply adjusting the concentration of H2O2 in reaction system. These nanoCeO2 could be dispersed in water and ethanol very well after reaction without using any surfactant. A possible growth mechanism was put forward to explain the morphologies evolution process based on TEM, SEM observations. There are not any other impurities were introduced into reaction, and the production ration is high enough, which supply a potential large-scale preparation method for CeO2 nanomaterials.

Attenuation and diel cycling of coal-mine drainage constituents in a passive treatment wetland: A case study from Lambert Run, West Virginia, USA

Abstract This study reports changes in coal-mine drainage constituent concentrations through a passive treatment wetland and over diel cycles. The purpose of the study was to determine what physiochemical mechanisms control attenuation of metals and if they varied by location and through time. The source water was slightly acidic (average pH 5.43); downstream degassing of CO2 contributed to an increase in pH prior to discharge from the site (average pH 7.05). Aluminum, Fe, rare earth elements (REE) and Y were removed to a greater extent than were Mn, Co and Ni. At acidic pH, the REE and Y were generally complexed by SO4. At higher pH, carbonate complexes became more important. The REE and Y concentrations were normalized to the North American Shale Composite standard; the normalized patterns were coherent near the source but anomalies of Ce and Y were present further downstream indicating oxidation and sorption processes. Four sets of diel-based samples were collected, one from a shallow, surface-flow wetland and three from a deeper, newly constructed wetland. Well-defined diel cycles were observed for concentrations of Si, Mn, Fe, Co, Ni, As, REE and Y in the shallow wetland. In all cases, the concentrations increased (up to 863%) during night and decreased during the day. These cycles had an inverse relationship with the temperature cycle (pH had no discernable cycle). The consistency of concentration cycles suggests a common mechanism, most likely associated with the formation of Fe oxyhydroxides. The increased rate of Fe2+ oxidation in warm water can account for the cycles in Fe; scavenging of the other elements by the Fe precipitate can account for the consistency of the cycles even though the elements include cations, anions ( H 2 AsO 4 - or HAsO 4 - 2 ), and neutral species ( H 4 SiO 4 0 ). While REE and Y had clear cycles in the constructed wetland, the other elements did not. This is partially due to the lower elemental concentrations (including Fe) but the cycles may also be damped by the deeper, slower-moving water. This study illustrates the dynamic nature of metal removal in passive treatment systems. Furthermore, it suggests that grab samples collected during daytime hours may underestimate the concentrations and flux of metals in these systems.

The EmsB Tandemly Repeated Multilocus Microsatellite: a New Tool To Investigate Genetic Diversity of Echinococcus granulosus Sensu Lato

Cystic echinococcosis (CE) is a widespread and severe zoonotic disease caused by infection with the larval stage of the eucestode Echinococcus granulosus sensu lato. The polymorphism exhibited by nuclear and mitochondrial markers conventionally used for the genotyping of different parasite species and strains does not reach the level necessary for the identification of genetic variants linked to restricted geographical areas. EmsB is a tandemly repeated multilocus microsatellite that proved its usefulness for the study of genetic polymorphisms within the species E. multilocularis, the causative agent of alveolar echinococcosis. In the present study, EmsB was used to characterize E. granulosus sensu lato samples collected from different host species (sheep, cattle, dromedaries, dogs, and human patients) originating from six different countries (Algeria, Mauritania, Romania, Serbia, Brazil, and the People's Republic of China). The conventional mitochondrial cox1 and nad1 markers identified genotypes G1, G3, G5, G6, and G7, which are clustered into three groups corresponding to the species E. granulosus sensu stricto, E. ortleppi, and E. canadensis. With the same samples, EmsB provided a higher degree of genetic discrimination and identified variations that correlated with the relatively small-scale geographic origins of the samples. In addition, one of the Brazilian single hydatid cysts presented a hybrid genotypic profile that suggested genetic exchanges between E. granulosus sensu stricto and E. ortleppi. In summary, the EmsB microsatellite exhibits an interesting potential for the elaboration of a detailed map of the distribution of genetic variants and therefore for the determination and tracking of the source of CE.

Effect of the synthetic parameters on the textural properties of one-pot mesoporous Al–Ce–Cu systems

Various samples of the Al–Ce–Cu ordered mesoporous oxide system were prepared by a single-step synthesis using n-propanol as solvent, aluminum sec-butoxide as Al precursor, metal stearates and/or metal nitrates as Cu and Ce sources. Different reagent types and reagents ratios were used in order to explore the role of these synthetic parameters in determining the chemical, textural and structural properties of the resulting materials. The study was carried out using nitrogen physisorption at 77 K, X-ray powder diffraction (XRPD), temperature-programmed reduction (H 2-TPR), temperature-programmed desorption of ammonia (NH 3-TPD) and FT-IR spectroscopy of adsorbed pyridine.

Mineralogy and Geochemistry of Paleocene Ultramafic- and Sedimentary-Hosted Talc Deposits in the Southern Part of the Sivas Basin, Turkey

AbstractTalc deposits, located mainly in three areas of north-central Turkey, are present in the ophiolitic series of the Cretaceous and in siliciclastic rocks of the Paleocene. Talc deposits related to ophiolites are between tectonite and cumulate occurring as beds and/or lenses and 0.1–3 cm thick fracture fillings within a 5 m brecciated zone with a vein-type bedding. Sedimentary-hosted talc beds and semi-rounded to angular talc grains (0.1–2 cm) range in thickness from 0.1 to 30 cm within marls and conglomerates. Talc veins form lenses (a few meters long) and spheroidal and/or ellipsoidal nodules (1–10 cm). Calcite, dolomite, serpentine and/or mixed-layered illite-smectite (I-S) minerals are encountered in the talc samples. Serpentine with positive U and Hf anomalies, and talc with positive Nb and Zr anomalies, and negative Ta and Ce anomalies are typically depleted in P and Ti, based on chondrite-normalized trace element patterns. The light rare earth element content of sedimentary-hosted talc with a negative Gd anomaly is richer than those of ultramafic-hosted talc with a negative anomaly for Eu as well as serpentine. Significantly, talc with a uniquely sedimentary origin tends to be the principal source of Nb, Hf, Zr, La, Ce, Pr and Nd with respect to serpentine. δ18O and δD values for talc range from +13.8 to +17.5‰ and −60 to −36‰, and those of serpentine are +9.4 and −88‰, indicating supergene conditions for sedimentary-hosted talc and hypogene for ultramafic-hosted talc. When compared with seawater, δ18O data indicate temperatures of 68°C and 80–98°C for the sedimentary- and ultramafic-hosted talc formations, respectively, and 100°C for serpentine, suggesting that talcification and serpentinization of ultramafic rocks both occurred at nearly the same time with various stages. All data show that the talc occurrences are divided into two types based on their mode of formation. The first corresponds to a serpentinization stage within the ophiolites. The others are the neoformation products of sedimentary deposition, diagenetic and post-diagenetic processes, respectively. Sedimentary-hosted talc also seems to have inherited trace element and isotopic compositions from the parent ultramafic rocks.

MOCVD of CeF3films on Si(100) substrates: synthesis, characterization and luminescence spectroscopy

CeF3 thin films have been deposited on Si(100) substrates by metal–organic chemical vapor deposition (MOCVD). The Ce(hfa)3·diglyme [Hhfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, diglyme = (CH3O(CH2CH2O)2CH3)] precursor has been adopted as a single source for both Ce and F components. This adduct has proved to be a good and reliable precursor, suitable for evaporation from the liquid phase due to its rather low melting point (75 °C).

In Situ Studies of the Nucleation Mechanisms of Tris(cyclopentadienyl)Cerium as Cerium Dopant Source in SrS:Ce Thin Films for Electroluminescent Displays

A systematic evaluation was made of the performance and efficiency of tris(cyclopentadienyl)cerium, Ce(CPD), as potential dopant source in atomic layer epitaxy (ALE) and chemical vapor deposition (CVD) of Ce-doped strontium sulfide (SrS:Ce) for thin-film electroluminescent display applications. In situ growth and characterization studies were carried out, without a vacuum break, of the adsorption and associated dissociation mechanisms of Ce(CPD) within the substrate temperature window typically employed in ALE and CVD SrS:Ce. Associated findings were compared to results from tetrakis(2,2,6,6-tetramethyl-3,5-heptadionato)cerium, which was used as a comparative performance baseline. In this respect, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry studies indicated that, within the typical thermal budget used in ALE and CVD of SrS:Ce films, the Ce(CPD) source decomposed more efficiently than its counterpart, as supported by the observation of reduced hydrocarbon-based surface contamination and a cleaner Ce phase. It was concluded that Ce(CPD) might be a better candidate than for applications as Ce dopant source in ALE and CVD SrS:Ce films. © 2001 The Electrochemical Society. All rights reserved.

Application of A 10 μg tin microcalorimeter in the field of low-energy X-ray metrology

LNHB (Laboratoire National Henri Becquerel) is responsible for the French radioactivity standards and the updating of the radionuclide table containing all available atomic and nuclear data. This implies decay scheme studies which require high-energy resolution spectrometry and also activity measurements using low threshold and high detection efficiency detectors. To explore the capabilities of cryogenic detectors for low-energy X-ray metrology, there has been a collaboration with the Institut d'Astrophysique Spatiale in order to develop a fast microcalorimeter with a tin absorber which guarantees a detection efficiency greater than 99.9% in the 1–6 keV energy range. A feasability study of a decay scheme analysis was carried out on this microcalorimeter with a 139 Ce source; preliminary results on relative intensities are presented.

Hydrothermal Synthesis of Two Types of Cerium Carbonate Particles

Ceria (CeO2) has received attention for various applications such as catalytic supports (for automotive exhaust systems), solid electrolytes in solid-oxide fuel cells, low-temperature (, 600 8C) oxygen sensors, additives for glass, stabilizers for ZrO2, glass polishers and so on. In general, a powder preparation method should meet several important criteria. For instance, an oxide precursor should have the desired morphology and chemistry that will decompose to the pure oxide at relatively low calcination temperatures. For one of the rare-earth oxide precursors, the formation, the chemical composition, the morphology and the decomposition of the rare-earth carbonates have been investigated by many researchers [1±4]. Hydrothermal synthesis is also an attractive method for the preparation of crystalline ceramic powders and has been employed for the synthesis of electronic ceramic powders. CeO2 and cation-doped CeO2 have been hydrothemally synthesized [5±8], and it has also been shown that controlling the growth of CeO2 particles is possible and that ultra®ne CeO2 particles can be hydrothermally prepared from Ce(IV) sources, starting with precipitation from the salts through the action of ammonia [7, 8]. Studies on the synthesis of Y2O3 ±ZrO2 powders by the hydrothermal technique in the presence of urea have been reported [9]. We showed that the angular nanocrystalline CeO2 powders with a cubic uorite structure were hydrothermally synthesized from cerium(IV) salt solutions in the presence of urea [10]. However, few researchers have reported the hydrothermal synthesis of powders in the presence of urea except for these examples. In this study, the crystal phase and the morphology of cerium carbonate particles hydrothermally synthesized from cerium (III) salt solutions in the presence of urea, and the effects of the concentration of urea on their crystal phase were investigated. Cerium(III) chloride (CeCl3 7H2O), cerium(III) sulfate (Ce2(SO4)3 8H2O), cerium(III) nitrate (Ce (NO3)3 6H2O) and urea (CO(NH2)2), all of laboratory purity, were used as the starting materials. A given quantity (20 cm) of a mixed solution of the cerium salt and urea in the desired concentrations was poured into a Te on bottle, with an inner volume of 25 cm, held in a stainless-steel vessel. After the vessel was sealed, it was placed in a thermostatted oven, heated and constantly rotated from 120 to 180 8C for 5 h. The precipitated powders were then washed and dried in an oven with an air atmosphere. The calcination of the powders was carried out from 300 to 900 8C for 1 h in a furnace in air. The crystalline phase identi®cation was performed by X-ray diffraction (XRD) using CuKa radiation. The crystallite size was estimated by linebroadening analysis. The re ection from the (2 2 0) plane of CeO2 was used for the crystallite size determinations. The precipitate morphology and size were examined by transmission electron microscopy (TEM). Speci®c surface areas of the as-synthesized and calcined powders were determined by the Brunauer±Emmett±Teller method. XRD patterns of the precipitates hydrothermally synthesized at 180 8C for 5 h from the various kinds of 0.1 mol dmy3 cerium(III) salt solutions in the presence of 0.3 mol dmy3 urea are shown in Fig. 1. The XRD patterns of the particles prepared from the cerium(III) nitrate and chloride solutions (Ce3‡ : 0.1 mol dmy3) were almost identical to the one reported for orthorhombic Ce2O(CO3)2 H2O [11, 12], which was closely related to the one reported for the mineral ancylite [13]. On the other hand, the bastnaesite structure, hexagonal Ce(OH) CO3, was formed along with a small amount of orthorhombic Ce2O(CO3)2 H2O from the cerium(III) sulfate solution (Ce3‡ : 0.2 mol dmy3). The change in the crystal phase of the synthesized cerium carbonate with an increase in urea concentration in the starting solution was investigated using

In Situ Pulsed Deposition Studies of Ce ( tmhd ) 4 on SrS Surfaces for Thin Film Electroluminescent Flat Panel Display Applications

In this paper, results are presented from a systematic investigation which aimed to evaluate the performance and efficiency of tetrakis(2,2,6,6‐tetramethyl‐3,5‐heptadionato)cerium(IV), or , as the cerium dopant source in the atomic layer epitaxy (ALE) of strontium sulfide (SrS) thin films for thin film electroluminescent (TFEL) display applications. For this purpose, in situ growth and characterization studies of the adsorption and associated nucleation mechanisms of on SrS surfaces were performed in a clustered system under tightly controlled ultraclean conditions. The growth experiments were carried out in a specially designed processing chamber under pulsed deposition conditions that emulated the ALE process. The samples were then transferred in situ, without exposure to air, to various characterization chambers where compositional and chemical analyses were readily performed. In particular, chemical evaluation by X‐ray photoelectron spectroscopy and time‐of‐flight secondary ion mass spectroscopy showed incomplete decomposition of the molecule with the observation of high carbon levels corresponding to ligands from the precursor. It is believed that these ligands sterically hinder subsequent adsorption and nucleation of the Sr source by poisoning the substrate surface, and therefore require repeated cycles of exposure to pulses of the Sr source and associated reactants to ensure their complete removal. It is thus suggested that the incomplete decomposition of the molecule is the primary cause for its poor efficiency as Ce source precursor, an observation supported by experimental findings from actual ALE manufacturing of SrS:Ce films for TFEL applications.