Preparation and characterization of OH‐functionalized magnetic nanogels under UV irradiation

A novel preparation method of net magnetic polymer nanogels with swollen shell was developed. UV‐induced photopolymerization of 2‐hydroxyethyl methacrylate (HEMA) was performed in the magnetite aqueous suspension, free of any additive to obtain monodisperse magnetic nanogels with swollen shell. Owing to the step‐growth polymerization of the monomer, the particle size of magnetic nanogels can be conveniently manipulated by changing the irradiation time and the volume of the monomer dropped. The crystalline structure of Fe₃O₄ core and chemical composition of PHEMA magnetic nanogels were characterized by using X‐ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis, respectively. Particle sizes, size distributions of magnetic nanogels in swollen state and dry state were measured by photo‐correlation spectroscopy (PCS) and transmission electron microscopy (TEM), respectively. The morphology of swollen magnetic nanogels and that of polymer capsules obtained from magnetic nanogels etched by hydrochloride acid were observed by TEM. The high magnetizations and superparamagnetic behaviors of naked Fe₃O₄ and magnetic nanogels at room temperature were confirmed by the measurement of hysteresis curves. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1283–1290, 2006     

Die entscheidende Mitwirkung der Metall- und Sauerstoffionen von Nickeloxid beim Ablauf der Oxidation von o-Xylol

The Decisive Cooperation of Metal and Oxygen Ions of Nickel Oxide During the Oxidation of o-Xylene As can be concluded from the experimental results at 450°C in the reaction mixtures consisting of N₂ O₂-o-Xylene, both nickel oxide pure and doped with Li₂O or In₂O₃ is unsuited as catalyst for the oxidation of o-xylene to phthalic anhydride. In contrast to NiO which ionosorbs both oxygen and o-xylene, NiO Li₂O, a strong ionosorbent for o-xylene, prevents the ionosorption of oxygen because of the large concentration of holes. Since gaseous oxygen does not react with ionosorbed o-xylene but a reduction of nickel oxide to metallic nickel has been observed in spite of the fact of enough oxygen in the gas phase it can be assumed that o-xylene is forced to remove oxygen ions from the NiO lattice under generation of oxygen-ion vacanxies and nickel atoms. The predominant portions of the reaction products are H₂O and CO₂. With undoped nickel oxide and NiO In₂O₃ which were not reduced under the same experimental conditions, the reaction products had roughly the same composition. The reduction of NiO Li₂O however will be prevented in a gas mixture with a high oxygen pressure which oxidizes the formed nickel atoms on the surface of NiO Li₂O to nickel oxide making possible the entrance of oxygen from the gas phase and, therefore, the oxidation of o-xylene. A turbulent motion of a 2-component catalyst powder from NiO-1mole% Li₂O covered with ionosorbed o-xylene and ZnO-1mole% In₂O₃ covered with ionosorbed oxygen in the same gas mixture resulted in the same reaction products as in the presence of sole NiO Li₂O under simultaneous reduction of nickel oxide. From that we can conclude that the oxidation of o-xylene by oxygen ions of NiO occurs more easily than the reaction with ionosorbed oxygen on ZnO In₂O₃ which obviously seems to be bounded too strongly. This result is also confirmed by the prevention of the oxidation of gaseous o-xylene in the presence of only ZnO In₂O₃. Finally, the operation of the carrier catalyst V₂O₅/TiO₂ which is employed for the oxidation of o-xylene to phthalic anhydride will be prevented to a large extent in simultaneous presence of nickel oxide either pure or doped with Li₂O and In₂O₃ in roughly the same amount. This result can be mentioned as a proof for the interaction of a 2-component catalyst the mechanism of which is at present not satisfactorily understood.     

Film formation from PS/AL2O3 nanocomposites prepared by dip‐drawing method

In this study, steady state fluorescence (SSF) and UV–vis (UVV) techniques were used to examine film formation from pyrene (P) labeled polystyrene (PS) latex/Al₂O₃ (PS/Al₂O₃) composites prepared by the dip‐drawing method. The effects of dip‐drawing rates and dipping time in Al₂O₃ sol on film formation behavior and the morphology of PS/Al₂O₃ films were investigated. Films were prepared first by casting PS dispersion on clean glass substrates which creates a close‐packed array of PS sphere (203 nm) templates. These templates were then covered with Al₂O₃ utilizing the dip‐drawing method for various dip‐drawing rates and dipping times in Al₂O₃ sol. The film formation of these composites was studied by annealing them at a temperature range of 100°C to 270°C and monitoring the scattered light (I_sc), fluorescence (I_P), and transmitted light (I_tr) intensities after each annealing step. The structural properties of the composite films were analyzed with a scanning electron microscope (SEM). The results demonstrated that the film formation behavior and morphology of composites depended mainly on dipping time, and no dependence on the dip‐drawing rate was observed. The optical results indicated that PS/Al₂O₃ films undergo complete film formation independent of the dip‐drawing rate and dipping time. Additionally, the film formation stages were modeled and the corresponding activation energies were determined. After completion of film formation, PS polymers were extracted to obtain porous Al₂O₃ thin films. Highly ordered porous structures were observed for long dipping time in Al₂O₃ sol but no change was observed for different dip‐drawing rates, confirming the optical data. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Effects of Al2O3 nanoparticles on the properties of glass matrix composites for sealant applications

Glass matrix composites (GMCs) have better mechanical properties than glass, which is beneficial for applications as sealants. This application scenario requires the GMCs sealants to withstand extreme service conditions for extended periods of time. In this study, a borosilicate glass as the matrix was filled with Al₂O₃ nanoparticles to prepare the GMCs through powder technology, and the effects of Al₂O₃ nanoparticles on the phase composition, thermal behavior, coefficients of thermal expansion (CTE), microstructure, wettability, viscosity and mechanical properties were systematically investigated. X-ray diffraction (XRD) patterns and thermal analysis results revealed that the Al₂O₃ particles, which were thermodynamically stable in the borosilicate glass after heat treatment, could be considered as rigid inclusions. As the mass fraction of Al₂O₃ nanoparticles increased, the CTEs of the GMCs and the wettability to metal surfaces gradually decreased, and an increasing viscosity was also observed with the addition of Al₂O₃ nanoparticles, which was attributed to the inhibition effect of the Al₂O₃ nanoparticles on glass viscous flow and apparently contributed to the residual voids. The mechanical properties of the heat-treated GMCs were enhanced by the Al₂O₃ nanoparticles but limited by structural defects such as residual voids and swollen bubbles, especially when the mass fraction of Al₂O₃ nanoparticles was large. The results thus demonstrate that an increased heat treatment temperature was expected to reduce the viscosity of the melts and promote the elimination of residual voids, but will inevitably cause the undesired bubble growth at the same time. Therefore, the content of Al₂O₃ nanoparticles in the glass matrix should be limited to a certain extent to ensure that the reinforcements can fully exert their strengthening effect.     

Die kathodische reduktion von ozon in sauren elektrolyten

The cathodic reduction of ozone ?O₃ + 2H⁺ + 2e → H₂O + O₂ ? on bright platinum was investigated in sulphuric acid electrolytes. Rest potentials deviate from the reversible values by ?350 to ?400 mV. They are determined by a mixed potential mechanism involving anodic oxygen evolution and the cathodic ozone reduction as half-reactions. Steady state polarization measurements were carried out. Current densities at the rest potential, which are analogous to exchangecd, are obtained by extrapolation of Tafel-lines to zero overvoltage and by determination of the charge  transfer resistance. A single electron transfer reaction is found to be the rate-controlling step which is occurring twice for the reduction of one molecule of ozone. Cathodic reaction orders of +0,5 and + 1 are evaluated with respect to [H⁺] and [p_O3]. A reaction mechanism is proposed according to

which is consistent with experimental data.Limiting currents are observed in the region of high cathodic polarization, which are diffusion controlled.     

Fabrication of high-quality alumina coating through novel,dual-particle aerosol deposition

High-quality alumina (Al₂O₃) coating has an extensive demand in the fields of optoelectronics, solar cells, and corrosion/impurity resistant coatings and cutting tools. The quality of alumina coating depends on its hardness and transparency. To obtain hard and highly transparent alumina coating, which is also a widely used ceramic material, a novel, aerosol deposition approach is presented in which the starting powder, used to fabricate Al₂O₃ ceramic coatings, is composed of angular and spherical Al₂O₃ particles. Films fabricated using angular:spherical Al₂O₃ particle mixtures with ratios of 10:0, 7:3, 5:5, 3:7, and 0:10, showed significant variation in surface roughness and microstructure. The dramatic morphology modulation of the 3:7 angular:spherical Al₂O₃ mixture film, resulting from the superposition hammering effect caused by the aerosol mixture, improved transmittance (84.7%) and hardness (13.6 GPa). Previous studies used high-energy approaches to optimize Al₂O₃ film properties. This dual-particle approach, however, produces Al₂O₃ film with excellent transmittance and hardness while achieving a fast coating speed (32 mm² × μm/min) without additional thermal treatment. Our proposed approach provides a novel and energy efficient method to produce transparent Al₂O₃ films with superior durability.     

Mechanismus der katalysierten Synthese von Kohlenwasserstoffen

On the mechanism of the catalysed synthesis of hydrocarbons . Recent results by independent research teams prove that, in hydrocarbon synthesis over metal catalysts in a reducing atmosphere, the dissociative adsorption of CO is of considerable importance. On the catalyst surface the two fragments, C_ads and O_ads, react swiftly with hydrogen to CH_x,ads and H₂O respectively. CH_x,ads can be either hydrogenated to methane or incorporated in growing chains. This process may be visualized as a cis insertion of a carbene CH_2,ads in a metal-alkyl bond. In the steady state the catalyst surface is predominantly covered with CO_ads, only a small fraction of the surface atoms carrying growing alkyl groups. These have been detected by ¹³C labelling as well as by IR spectroscopy.     

Facile Synthesis of Monodispersed In2O3 Hollow Spheres and Application in Photocatalysis and Gas Sensing

Monodispersed, agglomerate‐free In₂O₃ hollow spheres have been prepared via a simple synthetic route involving permeation and anchoring of In³⁺ ions with carbonyl groups of swollen commercial polymer beads in tetrachloroethylene solvent followed by thermal removal of the template cores in ambient air. The as‐synthesized hollow spheres exhibit a narrow size distribution with tunable particle size (0.5–1.2 μm) and shell thickness (62–230 nm) over the process variables examined, i.e., InCl₃ precursor concentration (4.5 × 10^?3–6.7 × 10 ^{? 2} M), reaction temperature (55°C–95°C), and reaction time (1–6 h). Kinetics calculation reveals that the formation of permeating In³⁺‐rich shell in the swollen template beads becomes energetically less favorable to proceed as the reaction time increases. This limits the maximum shell thickness attainable at the given process variables. The shell is nanoporous with a Horvath‐Kawazoe (HK) pore size of ~3 nm, which remains essentially unchanged as the process variables alter. The In₂O₃ hollow spheres with an increased Brunauer‐Emmett‐Teller (BET) surface area (up to 329 m²/g) show an improved capability in photodegradation of aqueous methylene blue (MB) dye under UV exposure as well as an increased sensitivity for CO‐gas detection. This metal‐implantation scheme is general and can be extended to the synthesis of other hollow materials in various solvent liquids.     

EXAFS investigations of lanthana-promoted Rh/SiO2 catalysts

EXAFS investigations at the Rh K edge of lanthana-promoted Rh/SiO₂ catalysts showed that the local environment of the Rh ions in the oxidic catalyst precursor state did not depend on the La₂O₃ content and resembled that of Rh₂O₃. No LaRhO₃ formation could be detected. In the reduced state, EXAFS as well as H₂ and CO chemisorption demonstrated that La₂O₃ increased the Rh dispersion. Covering of the Rh metal particles by La₂O₃ was minor, because during catalyst preparation, La was impregnated prior to Rh.     

Crystallization Atmosphere and Substrate Effects on the Phase and Texture of Chemical Solution Deposited Strontium Niobate Thin Films

Strontium niobate (Sr:Nb  =  1:1) thin films were prepared via chemical solution deposition on (001)‐oriented SrTiO₃, (001)_p‐oriented LaAlO₃, (0001)‐oriented sapphire, and polycrystalline alumina substrates. Crystallization in oxygen at 1000°C yielded Sr₂Nb₂O₇ films on all substrates with strong (010) orientation. Films on LaAlO₃ and SrTiO₃ single‐crystal substrates possessed a small amount of preferred in‐plane orientation, whereas films prepared on sapphire and polycrystalline alumina substrates were fiber textured. Films crystallized at 900°C in a low oxygen atmosphere (~10 ^{? 21} atm pO₂) formed a randomly oriented polycrystalline perovskite, SrNbO_3?δ on all substrates. A similar set of films crystallized at 900°C at a slightly higher oxygen partial pressure (~10^?15 atm pO₂) was comprised of Sr₂Nb₂O₇ and SrNbO_3?δ phases, exposing the dependence of phase formation on oxygen partial pressure. When subjected to a high‐temperature anneal in oxygen, the SrNbO_3?δ phase is shown to transform into Sr₂Nb₂O₇, however, Sr₂Nb₂O₇ did not significantly reverse transform into SrNbO_3?δ after annealing in low oxygen partial pressure atmospheres.     

Zum Einfluß von Schutzgruppen bei der Metathese fettchemischer Verbindungen

The Influence of Protecting Groups in the Metathesis of Oleochemicals Unsaturated fatty acids and fatty alcohols can be only converted by metathesis in form of their derivatives requiring high concentrations of catalyst. Using the cross-metathesis of various esters (methyl, iso-propyl, tert.-butyl) of 10-undecenoic acid with 4-octene as well as the cross-metathesis of various derivatives (acetate, pivalate, tosylate, trimethylsilylether) of 10-undecenol or oleyl-alcohol with symmetric olefins (4-octene or ethylene) as model reactions, the influence of protecting groups for oleochemicals concerning their metathesis-reactivity was studied. The trimethylsilyl-group turned out to be an excellent protecting group for unsaturated fatty alcohols as educts for metathesis. With Re₂O₇/Al₂O₃-SnMe₄ as catalyst the cross-metathesis of 10-undecenyl-trimethylsilylether with 4-octene lead to a derivative of 10-tetradecenol and 1-pentene even using a molar ratio of Re₂O₇: trimethylsilylether of 1:500.     

Bestimmung des Xanthophyllgehaltes von Pflanzenölen

Determination of Xanthophyll Content of Vegetable Oils The DGF official method F — II 2 enables the separation of carotenoid hydrocarbons from the unsaponifiables using a Al₂O₃ column. This method can be extended by the successive use of polar solvents. Thus, polar carotenoids can also be separated. Spectrum of each fraction from the Al₂O₃ column is obtained and the fractions are further separated in a MgO-celite column. Identification of individual carotenoids is done on the basis of absorption spectra as well as the nature and number of polar groups determined by thin-layer chromatography on silica gel plates. Content and composition of carotenoids in several vegetable oils, such as soybean, sesame, sunflower, corn germ and low-erucic rapeseed oil were determined by this technique. All these oils contain mainly dihydroxy carotenoids.     

Graphene nanoplatelets/Cr2O3 nanocomposites as novel nanoantibiotics: Towards control of multiple drug resistant bacteria

Drug resistance resulting due to the abuse of antibiotics can possibly be fatal for human beings. It, therefore, is required to develop novel nanoantibiotics to fight with the bacterial infections. In this work, we report graphene nanoplatelets/Cr₂O₃ nanocomposites (GNPs/Cr₂O₃) as a potential nanomedicine. Antibacterial characteristics of GNPs/Cr₂O₃ nanocomposites have been investigated against Pseudomonas aeruginosa and Staphylococcus aureus. GCr₂O₃-II with the optimized GNPs’ content shows excellent antibacterial performance with 84.25% growth inhibition of S. aureus (Gram-positive bacteria) and 80.76% growth inhibition of -P. aeruginosa (Gram-negative bacteria). This can be attributed to the synergistic contribution of Cr₂O₃ nanoflakes and GNPs/Cr₂O₃ nanocomposites, towards bacterial membrane disruption, that may be caused by the sharp edges of GNPs and induction of the oxidative stress by Cr₂O₃ nanoflakes. Therefore, this study suggests that GNPs/Cr₂O₃ nanocomposites can be employed as an innovative nanoantibiotics for pathogen control.     

The macromolecular nature of bituminous coal

Considerable insight into the macromolecular state of coal has been obtained by examining the optical anisotropy of untreated solvent-swollen, and chemically derivatized thin sections of coal. From the effect of pressure on the optical anisotropy, and from the rate and degree of recovery after release of pressure, it was found possible to determine whether the coal is in a plastic or rubbery state, whether a rubbery state is cross-linked and how mobile the macromolecular chain segments are. The experimental technique utilized for this work was transmission optical microscopy in polarized light of uncontaminated thin sections of vitrinite from a bituminous coal. The study included in-situ microscopic examination of swollen coal immersed in pyridine, THF, toluene and several other solvents. Some samples were O-methylated to assess the impact of hydrogen bonding. New results and conclusions derived from this study include: (1) the vitrinite of raw bituminous coal is a plastic macromolecular substance; (2) coal swollen in pyridine (and some other ‘specific’ solvents) is a cross-linked rubber and its macromolecular chain segments have substantial mobility; (3) when pyridine-extracted coal dries, it reverts to a plastic; (4) the large discrepancies previously found between values of M_c (molecular weight between crosslinks) measured by solvent-swelling and by stress-strain techniques is caused by differences in secondary interactions; (5) various solvents can, by their effect on secondary interactions, create appreciably different macromolecular structures in the coal; (6) different solvents, depending on their effect on secondary interactions in the coal, can be expected to extract chemically different molecules from a coal - rates of extraction and the ability of solvents to extract larger molecules should also differ; (7) O-methylated coal is a plastic, and thus, in addition to hydrogen bonding, other secondary interactions are of great importance; (8) it is likely that in their dry condition, solvent-treated coal and O-alkylated coal, as well as untreated coal, are in glassy states; (9) pyridine by itself appears to relax substantially all secondary interactions which are weakened by O-methylation, only permanent bonds are not relaxed; (10) previous measurements of M_c can now be reassessed in view of these results.     

The effect of Pd/Al2O3 pretreatment on catalytic activity in cyclopentane/deuterium exchange

Big variations in overall activity and product selectivity in the cyclopentane/deuterium exchange reaction were found in effect of various pretreatments of two chlorine‐free Pd/γ‐Al₂O₃ catalysts. The most important changes are observed when severely prereduced (at 600 °C) Pd/Al₂O₃ catalysts have been reoxidised and mildly rereduced: the multiple type of exchange, typical of mildly pretreated Pd catalysts, is replaced by a stepwise mode, and a big increase in catalytic activity occurs. At this state, the Pd/γ‐Al₂O₃ catalysts retain some water (as surface hydroxyls) generated by reoxidation and mild reduction. Deuterium spillover from Pd onto alumina and changes in acidity of alumina are invoked to rationalize the kinetic results. Changes in the state of Pd after various pretreatments, as probed by temperature‐programmed hydride decomposition, can hardly be correlated with changes in the catalytic behaviour in the exchange reaction. This revised version was published online in August 2006 with corrections to the Cover Date.     

Sorption von Silber an chlormethyliertem Polystyrol

Silver ions are bound on polystyrene containing ? CH₂Cl groups with a distribution coefficient of about 100 ml/g, but they are not bound on polystyrene itself. This indicates direct interaction between Ag⁺ ions and the chlorine atoms of the ? CH₂Cl groups in the sense of formation of a 1:1 complex. In presence of 0.1 mol/l of ammonium ions somewhat smaller distribution coefficients are found in the range from pH 4 to pH 6. In presence of 10^?3 mol/l of Na₂S₂O₃ the distribution coefficients are only about 6 ml/g. From solutions, however, containing 1 mol/l of NaCl or 0.1 mol/l of Na₂S₂O₃ or 10^?3 mol/l of NaCN, silver is not sorbed in measurable amounts, because complexation in solution predominates.     

MOCVD deposition of CoAl2O4 films

Cobalt aluminate (CoAl₂O₄) thin films were grown in a low-pressure hot wall metal organic chemical vapour deposition (MOCVD) reactor on Si(1 0 0) and quartz substrates with a total pressure of 2 Torr using bis(η⁵-cyclopentadienyl)Co(II) [Co(η⁵-C₅H₅)₂] and aluminium dimethylisopropoxide [AlMe₂(OⁱPr)] as precursors at 500 and 900 °C. Films showed a dark-brown and dark-green colouration, respectively, and after an overnight heat treatment in air at 1200 °C, they turned blue. Film microstructure, composition and morphology were investigated in detail by X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS) analyses. Films were polycrystalline and the UV-vis spectra showed three electronic transitions allowed by the spin (540-630 nm range) characteristic of Co(II) ions with 3d⁷ configuration in tetrahedral coordination. SEM micrographs of the heat-treated CoAl₂O₄ samples revealed the presence of agglomerated crystallites with a highly porous structure.     

Benzyltitanium- und -zirconium/Al2O3-Katalysatoren zur partiellen Hydrierung von Acetylen

Benzyl Titanium and Zirconium Alumina Catalysts for Partial Hydrogenation of Acetylene Benzyl titanium and zirconium compounds of the types Bzl₄M, C₅H₅MBzl₃, and (C₅H₅)₂MBzl₂ form surface compounds on dehydroxylated alumina (15% α-, and 85% δ-Al₂O₃) which on hydrogenolysis yield TiH- and ZrH-species. The supported systems were studied with respect to catalytic activity in the partial hydrogenation of acetylene. Supported (C₅H₅)₂TiBzl₂ was proved to be inactive and the systems C₅H₅TiBzl₃(Al₂O₃) and Bzl₄/Al₂O₃ catalyze the formation of polyacetylene, but catalysts containing benzyl zirconium species are suitable for the partial hydrogenation of acetylene. Acitivity and selectivity of the system C₅H₅ZrBzl₃/Al₂O₃ are comparable to industrial used Pd/Al₂O₃ catalysts.     

Solid state reactions in highly dispersed Ce1−xYbxO2−y-Al2O3 system

This paper reports the results of studies on the interaction of Ce_1−xYb_xO_2−y mixed oxide nanocrystals (x=0.3 and 0.5) with gamma Al₂O₃. Nano-sized (3–4 nm) crystalline Ce-Yb mixed oxides, prepared by a water-in-oil (W/O) microemulsion technique, or simple co-impregnation by aqueous solutions of lanthanide ions, were supported on high surface area gamma alumina. Solid state reactions occurring in these systems upon heat treatment in air or hydrogen at 900–1100 °C were studied by TEM, SAED and XRD techniques. As a result of solid state reactions between pure or mixed lanthanide oxides and high surface area Al₂O₃, various aluminates were formed, depending on the heating temperature and atmosphere. Lattice parameters measured for the Yb₄Al₂O₉ (monoclinic) and CeAlO₃ (tetragonal) aluminates formed in Ce_0.5Yb_0.5O_1.75-Al₂O₃ and CeO₂+Yb₂O₃-Al₂O₃ systems suggest that they may contain other Ln-ions in the structure, and thus should be described as Ce_1−aYb_aAlO₃ and (Yb_1−bCe_b)₄Al₂O₉. Similar products were formed from solid state reactions in Ce-rich (CeO₂-Al₂O₃ and Ce_0.7Yb_0.3O_1.85-Al₂O₃) or Yb-rich (Yb₂O₃-Al₂O₃ and Ce_0.5Yb_0.5O_1.75-Al₂O₃) systems. The author postulates that, different solid state reaction routes were taken, depending on the Yb-ions concentration in the oxide structure, which was connected with the microstructure of lanthanide oxides (F or F# for Ce-rich systems and C or C# for Yb-rich systems).     

Influences of oxide chemical modified on microstructure and electrical properties of PbTiO3-Bi(Ni1/2Ti1/2)O3

The piezoelectric ceramics 0.45PbTiO₃-0.55Bi(Ni_1/2Ti_1/2)O₃ doped with PbO, Bi₂O₃, NiO and TiO₂ were synthesized by conventional solid state reaction method. Thereafter, the structural, ferroelectric and piezoelectric properties of modified ceramics were investigated systematically. By adding Bi₂O₃, NiO and TiO₂, the leakage current of ceramics was found to diminish pronouncedly. Moreover, the coercive field was observed to decrease by modification with TiO₂ in these ceramics. It was also proven that NiO can only be added in the B-site in PT-55BNT from the results of X-ray photoelectron spectroscopy analysis. Therefore, the modification with oxides can inhibit the volatilization of Pb during the sintering process that eventually improves the performance of materials.