Maximum Annealing Temperature Research Articles

Li4Ba[BN2]2 – Structure and Vibrational Spectra

The nitridoborate Li4Ba[BN2]2 was synthesized from a 4:1 molar ratio of Li3[BN]2 and Ba3[BN2]2 in an arc‐welded niobium ampoule at a maximum annealing temperature of 1173 K. The structure was refined from single‐crystal X‐ray diffractometer data: new type, P1, a = 533.9(2), b = 585.0(3), c = 860.6(4) pm, α = 80.72(3), β = 73.84(6), γ = 89.87(4)°, wR2 = 0.1196, 1429 F2 values, 50 variables. The Li4Ba[BN2]2 structure contains two crystallographically independent [BN2]3– units with 134 pm B–N distance, which are slightly bent: 178° for N2–B1–N1 and 175° for N4–B2–N3. Due to the high lithium content both [BN2]3– units have a strongly distorted coordination by 8Li+ + 3Ba2+. The four crystallographically independent lithium cations show distorted tetrahedral coordination by [BN2]3– units with Li–N distances ranging from 195 to 247 pm. IR and Raman spectra show the typical vibrations of the [BN2] unit along with a well‐resolved splitting of the ν(10Β) and ν(11B) frequencies.

SYNTHESIS AND PHASE ANALYSIS OF FLUORINE-DOPED PEROVSKITES BASED ON BARIUM-CALCIUM NIOBATES

The paper takes into account the fact that today, as a material for the electrolyte of solid oxide fuel cells, the compounds with a perovskite-like structure characterized by oxygen-ion conductivity in the dry air and proton conductivity in the air atmosphere are actively studied. The possibility of proton defects in these compounds is due to the presence of oxygen vacancies. The presence of vacant positions in the oxygen sublattice promotes reversible dissociative absorption of water from the gas phase and the appearance of proton conductivity. An example of a phase characterized by a perovskite structure and having an oxygen deficiency in the anion sublattice is barium-calcium niobate Ba 2 CaNbO 5,5 described in the literature as an oxygen-ion and proton conductor. Isovalent and heterovalent doping of cationic sublattices is the one of methods of modification of this type structure and optimization of physicochemical properties of complex oxide materials. However, the development of anionic doping can be an alternative for the obtaining of new materials with improved properties. It was established that the anionic substitution F − →O 2− leads to increase in oxygen and proton conductivities under small fluorine concentration (a mixed anion effect). The present research is an extension of the study of the effect of heterovalent anionic doping on oxygen-ion and proton transport. In this paper, the fluorine-doped complex oxides based on barium-calcium niobate Ba 2-0,5x CaNbO 5 , 5-x F x were obtained, X-ray analysis was performed. The phases were made by the anionic doping of oxygen sublattice of niobate barium-calcium Ba 2 CaNbO 5,5 by fluorine ions. The synthesis was carried out by a solidphase method, the maximum annealing temperature was 1300 о С. All the samples (0 < х ≤ 0,4) were single-phase and characterized by the cubic structure of a double perovskite. It has been established that the introduction of ions with a smaller radius (F - ) leads to a decrease of the lattice parameter of the fluorine-substituted compositions compared with the undoped barium-calcium niobate Ba 2 CaNbO 5,5 .

SYNTHESIS AND HYDRATION IN THE NEW Cl-SUBSTITUTED PEROVSKITE BASED ON BARIUM-CALCIUM NIOBATE Ba2CaNbO5.5

The paper deals with one of the important directions of modern materials science, namely the development and creation of new materials suitable for use in real electrochemical devices including components of solid oxide fuel cells such as electrolytic materials. In this regard, there is the task of finding inexpensive and technological solid electrolyte with high conductivity and stability in oxidizing and reducing atmosphere. Currently, promising devices are a medium temperature SOFC (200-500oC). Medium temperatures are the most optimal region in terms of energy costs. Promising ionic and protonic conductors for this temperature range are electrolytes based on the oxygen deficient complex oxides. The paper focuses on barium-calcium niobate which is well known oxygen-ion and proton conductor. The cationic substitution is the most common way for improving their transport properties. The anionic substitution is the new method which leads to increase the ionic and proton conductivity. Thus, the example of the proton conductor barium indium shows the principle possibility of substituting the fluoride and chloride ions for oxygen ions, that was accompanied by an improvement of the transport properties of halogenated phases with a low dopant concentration relative to the undoped matrix. In this paper, the novel type of protonic electrolytes – chlorine-substituted barium-calcium niobate Ba2CaNbO5.5-δ/2Clδ – was obtained for the first time. The synthesis was carried out by a ceramic method with a maximum annealing temperature of 1300 °C. It was found that the complex oxide obtained was characterized by the cubic structure of a double perovskite. The introduction of chloride ions, which have a large radius relative to oxygen ions, leads to an increase of the unit cell parameter. It is proved that the composition Ba2CaNbO5.5-δ/2Clδ was capable of dissociative absorption of water from the gas phase; the water uptake was lowered compares with the matrix composition Ba2CaNbO5.

High Efficiency Activation of Phosphorus Atoms in 4H-SiC by Atmospheric Pressure Thermal Plasma Jet Annealing

In this study, the application of atmospheric pressure thermal plasma jet (TPJ) annealing for impurity activation in 4H–SiC is reported. The activation of phosphorus atoms implanted at 300°C in 4H–SiC by TPJ irradiation and analysis of its crystallinity are investigated. At the maximum annealing temperature of 1630°C, the minimum resistivity value is 3.1 mΩ·cm and the maximum carrier concentration value is 2.0 × 1020 cm−3. Orientation analysis suggests that the sample implanted at 300°C was recrystallized to a 4H–SiC(0001) structure after 1630°C annealing. Furthermore, a significant increase in the carrier concentration was observed with the increasing cooling rate during the activation annealing process. Rapid cooling may suppress the impurity deactivation. These results suggest that short-time high-temperature TPJ irradiation annealing is effective for P dopant activation in 4H–SiC.

Improved fire resistance by using slag cements

Concrete is a composite material that mainly consists of mineral aggregates bound by the matrix of hardened cement paste. Composition and microstructure of hardened cement paste have important influences on the properties of concrete exposed to high temperatures. An extensive experimental study was carried out to analyse the post-heating characteristics of concretes subjected to temperatures up to 800 °C. Major parameters of our study were the slag content of cement (0, 16, 25, 41 or 66 m%) and the value of maximum annealing temperature. Our results indicated that (1) the number and size of surface cracks as well as compressive strength decreased by the increasing slag content of cements due to elevated temperature; (2) the most intensive surface cracking was observed by using Portland cement without addition of slag. The increasing slag content of cement increased the relative post-heating compressive strength. Tendencies of surface cracking and reduction of compressive strength were in agreement, i.e. the more surface cracks, the more strength reduction.

Improving Reversible Capacities of High-Surface Lithium Insertion Materials – The Case of Amorphous TiO2

Chemisorbed water and solvent molecules and their reactivity with components from the electrolyte in high-surface nano-structured electrodes remains a contributing factor toward capacity diminishment on cycling in lithium ion batteries due to the limit in maximum annealing temperature. Here, we report a marked improvement in the capacity retention of amorphous TiO2 by the choice of preparation solvent, control of annealing temperature, and the presence of surface functional groups. Careful heating of the amorphous TiO2 sample prepared in acetone under vacuum lead to complete removal of all molecular solvent and an improved capacity retention of 220 mAh/g over 50 cycles at a C/10 rate. Amorphous TiO2 when prepared in ethanol and heated under vacuum showed an even better capacity retention of 240 mAh/g. From Fourier transform infra-red spectroscopy and electron energy loss spectroscopy measurements, the improved capacity is attributed to the complete removal of ethanol and the presence of very small fractions of residual functional groups coordinated to oxygen-deficient surface titanium sites. These displace the more reactive chemisorbed hydroxyl groups, limiting reaction with components from the electrolyte and possibly enhancing the integrity of the solid electrolyte interface. The present research provides a facile strategy to improve the capacity retention of nano-structured electrode materials.

Plasma-activated direct bonding of patterned silicon-on-insulator wafers to diamond-coated wafers under vacuum

Direct wafer bonding requires the surfaces to have low surface roughness (Ra<0.5nm) as well as to be free of any particles or contaminants. Meeting these requirements for wafers patterned with lithography and dry etching presents a serious problem in terms of removal of photoresist residue and etch-related particles, which would require expensive additional equipment to be removed. In this study, we propose the use of chemical mechanical polishing (CMP) to be performed after all lithography and dry etch process steps involving several masks are completed. To reduce the adverse effect of any remaining slurry that might reside in the etched structures, we also propose to reduce the maximum annealing temperature from 550°C down to 300°C. The effect of lower annealing temperature on bonding is compensated using a sequential plasma activation with 60s of O2 followed by 90s of N2 on contacting surfaces made of silicon dioxide to achieve successful wafer bonding. Initial plasma activation with O2 additionally serves as a final cleaning step whereas the following activation with N2 for an extended duration is to fully activate the surface for direct bonding. This proposed technique can motivate the use of direct wafer bonding for microfabrication of advanced MEMS devices.

Study of Magnetic Shielding Materials and Fabrication of Magnetic Shield for Superconducting Cavities

Magnetic properties of Cryophy were measured at room and cryogenic temperatures using ring samples. Sample-to-sample variation in permeability was evaluated in addition to measurement error. Permeability dependence on the maximum annealing temperature was examined using ring samples annealed at 1100 °C and 1170 °C. From these data, Cryophy was chosen as magnetic shielding material for the superconducting cavities in the main linac section of the cERL (compact Energy Recovery Linac) at KEK. Magnetic properties of Cryophy are presented along with the results of simulation based on the data obtained. The result of the high-power test of the cERL main linac cavities is reported at the end.

P‐91: What is the Ideal ITO Composition for Touch Sensor Depositions on Flexible Substrate made with Rotary Cathodes?

AbstractCoating properties on various PET‐substrates for four ITO compositions, i.e. 90/10, 92.5/7.5, 95/5, 97/3 (10, 7.5, 5 and 3 wt% SnO2 in the rotary ceramic sputtering target) at a maximum annealing temperature of 150°C were compared. Coating crystallization improves with less Sn doping. ITO‐92.5/7.5 yields optimal electrical properties on hard‐coated and bare PET.

Mechanical behavior and optical transparency of polyamide 6 of different morphology formed by variation of the pathway of crystallization

The phase composition and supermolecular structure of polyamide 6 (PA 6) melt-crystallized on cooling at different rates or cold-crystallized at different temperatures were characterized and related to the optical transparency, stiffness and the stress–strain behavior. Cold-crystallization results in non-spherulitic formation of γ-mesophase or α-crystals, depending on the maximum annealing temperature. Both mesophase and crystals are of nodular shape. Melt-crystallization at low supercooling leads to formation of lamellar α-crystals and spherulites, while at high supercooling the nodular mesophase is forming. The absence of spherulites in cold-crystallized PA 6 films leads to high see-through clarity which is in contrast to the slowly melt-crystallized samples with opaque appearance. While Young’s modulus and the glass transition temperature increase with increasing crystallinity, for samples of identical crystallinity stiffness is considerably higher if the crystals are of lamellar rather than of nodular shape. The higher glass transition temperature of cold-crystallized PA 6 is related to a higher rigid amorphous fraction than in melt-crystallized samples pointing to a stronger coupling of the amorphous phase to ordered domains.

The rigid amorphous fraction of cold-crystallized polyamide 6

The rigid amorphous fraction (RAF) of polyamide 6 ordered/crystallized on heating initially fully amorphous glassy samples has been analyzed. Variation of the maximum annealing temperature allowed generation of partially ordered samples with different amount, perfection and morphology of mesophase or crystals. In samples with low fraction of mesophase between 0 and 20 %, the RAF increases with increasing mesophase fraction to reach a maximum value of 50 %. Further increase of the fraction and perfection of the ordered phase achieved by annealing at high temperature leads to a decrease of the RAF. The ratio between mobile and rigid amorphous fractions increases with increasing crystallinity, suggesting increasing decoupling of crystals and amorphous phase in samples of high crystallinity, and confirming results obtained earlier on poly(ethylene terephthalate) and isotactic polypropylene. The study contains a comparison of the RAF estimated from calorimetric analysis of the heat-capacity increment and dynamic-mechanical analysis of the area of the loss-factor peak on devitrification the mobile amorphous fraction, and a discussion of the effect of the phase composition of cold-ordered/crystallized PA 6 on the stiffness.

Morphology of cold-crystallized polyamide 6

The structure of cold-crystallized polyamide 6 (PA 6) has been analyzed by wide-angle X-ray scattering, atomic force microscopy, and polarizing optical microscopy. It has been found that ordering of initially fully amorphous and glassy PA 6 on slow heating to temperatures higher than the glass transition temperature results in formation of spatially non-organized short lamellae/nodules with a size depending on the maximum annealing temperature. In contrast, melt crystallization at low supercooling is connected with formation of spherulites and laterally extended lamellae. The observed experimental results demonstrate that crystals of qualitatively different morphology and higher-order organization can be generated by variation of the pathway of crystallization. It is assumed that the different structures obtained in melt- and cold-crystallized samples are related to heterogeneous and homogeneous nucleation, respectively.

Competitive device performance of low-temperature and all-solution-processed metal-oxide thin-film transistors

In this Letter, we described a solution-processed indium-gallium-zinc oxide thin-film transistors (TFTs) with a solution-processed aluminum oxide phosphate gate dielectric, fabricated at a maximum annealing temperature under 350 °C to be applicable to conventional fabrication process of flat-panel displays (FPDs). The solution-processed TFTs exhibited competitive device characteristics under 350 °C, including a field-effect mobility of 4.50 cm2/Vs, an on-to-off current ratio of ∼109, a threshold voltage of 2.34 V, and a subthreshold gate swing of 0.46 V/dec, making them applicable to the future backplane of FPDs.

Performance modification in solution-processed SnZnO thin film transistor

AbstractTin zinc oxide (SnZnO) thin film transistors (TFTs) with different component fraction fabricated by solution process were reported. Sn chloride and Zn acetate were used as precursor and the maximum annealing temperature was 500°C. The electrical characteristics of TFTs were acutely affected by the molar ratio between Sn and Zn in the lattice, and showed the highest mobility and on-to-off ratio of about 17 cm2/Vs and 2×106, respectively. The origins of the high performance were traced through both structural and electrical aspects. Sn was generally considered to offer carrier path by superposition of s orbital, but it was found that the increase of Sn fraction only below specific value in lattice contributed to increase mobility, which could be explained by the structural distortion and the defect generation. Zn atoms introduced in the lattice were necessary to control both mobility and carrier concentration. From these results, the solution-processed SnZnO TFT with high performance was suggested.

Structure, Stresses and Stress Relaxation of TiN/Ag Nanocomposite Films

Morphology, structure and thermal behavior of magnetron sputtered TiN/Ag nanocomposite thin films deposited at 150 degrees C with an Ag content in the range of 7 to 45 at% were characterized. The films were thermally cycled and the relationship between Ag content, film structure and stress development is analyzed. The results indicate that the residual stresses in as-deposited films and the behavior during heating are determined by the film structure and the plastic deformation of the Ag phase. The increasing plastic deformation with increasing Ag content causes significant changes in the stress-temperature behavior. While films with low Ag content show a plateau in compressive stress from deposition temperature up to 280 degrees C followed by stress relaxation, films with higher Ag content exhibit a zero stress level from deposition temperature up to the maximum annealing temperature. During cooling, all films exhibit linear thermo-elastic behavior, where the slope of the stress-temperature curves also depends on the Ag content.

Giant magnetoresistance effect in Co/Cu/Co nanostructures

The giant magnetoresistance effect (GMR) in Co/Cu/Co nanostructures is investigated in association with different sets of experimental conditions. GMR shows an up–down variation with increasing Co film thickness, with a peak for 6 nm thickness. A rather similar trend was observed in annealed samples with maximum annealing temperature of 400 °C. There is also a tendency of GMR to change with the number of Co/Cu bilayers and argon gas pressure introduced during the deposition, as indicated by the unstable wavy like curves.

Nanogranular MgB2 thin films on SiC buffered Si substrates prepared by an in situ method

MgB2 thin films were deposited on SiC buffered Si substrates by sequential electronbeam evaporation of a B–Mg bilayer followed by in situ annealing. Theapplication of a SiC buffer layer enables the maximum annealing temperature of830 °C to be reached. Transmission electron microscopy analysis confirms the growth of a nanogranularMgB2 film and thepresence of a Mg2Si compound at the surface of the film. The 150–200 nm thickfilms show a maximum zero resistance critical temperatureTC0 above 37 K and acritical current density JC∼106 A cm−2 at 11 K.

A Study on Pt/Al Reaction Mechanism in the FeRAM Device Integration

The capacitor contact barrier(CCB) layers have been introduced in the FeRAM integration to prevent the Pt/Al reaction during the back-end processes. Therefore, the interdiffusion and intermetallic formation in <TEX>$Pt(1500{\AA})/Al(3000{\AA})$</TEX> film stacks were investigated over the annealing temperature range of <TEX>$100\sim500^{\circ}C$</TEX>. The interdiffusion in Pt/Al interface started at <TEX>$300^{\circ}C$</TEX> and the stack was completlely intermixed after annealing over <TEX>$400^{\circ}C$</TEX> in nitrogen ambient for 1 hour. Both XRD and SBM analyses revealed that the Pt/Al interdiffusion formed a single phase of <TEX>$RtAl_2$</TEX> intermetallic compound. On the other hand, in the presence of TiN(<TEX>$1000{\AA}$</TEX>) barrier layer at the Pt/Al interface, the intermetallic formation was completely suppressed even after the annealing at <TEX>$500^{\circ}C$</TEX>. These were in good agreement with the predicted effect of the TiN diffusion barrier layer. But the conventional TiN CCB layer could not perfectly block the Pt/Al reaction during the back-end processes of the FeRAM integration with the maximum annealing temperature of <TEX>$420^{\circ}C$</TEX>. The difference in the TiN barrier properties could be explained by the voids generated on the Pt electrode surface during the integration. The voids were acted as the starting point of the Pt/Al reaction in real FeRAM structure.

27.2: Poly‐Si Thin‐Film Transistors Using Polysilazane‐Based Spin‐On Glass for All Dielectric Layers

AbstractPolycrystalline silicon thin‐film transistors (poly‐Si TFTs) with all layers of dielectric made from polysilazane‐based spin‐on glass (PS‐SOG) have been developed for the first time. The maximum annealing temperature of the PS‐SOG was at 400 °C. The electrical characteristics of poly‐Si TFTs with PS‐SOG as a gate dielectric are stable and the gate leakage current is sufficiently low. PS‐SOG is expected to realize CVD‐free deposition of dielectric layers and remarkable cost reduction of poly‐Si TFTs.

Creep of thin film Au on bimaterial Au/Si microcantilevers

We examine creep of thin film Au on curved bimaterial Au/Si microcantilevers. Time-dependent inelastic strains in the Au film lead to gradual changes in the microcantilever curvature over time. Curvature–temperature–time experiments are used to examine the effects of hold temperature and maximum annealing temperature on the inelastic response of the Au films. Experiments reveal inelastic strains in the Au films due to creep, recovery, and microstructural coarsening. At moderate hold temperatures, 30 °C < T < 175 °C, inelasticity in the Au films is observed to be a competition between creep and recovery. Creep strains are driven by tensile stresses in the film and serve to decrease the microcantilever curvature towards the equilibrium curvature of the underlying Si beam. Strains due to recovery of the metastable Au cause contraction of the film and the development of intrinsic tensile film stresses. At higher hold temperatures T>175 °C, the response of the film is dominated by microstructural coarsening which leads to an expansion of the film, the development of intrinsic compressive film stresses, and hillock formation. The recovery and microstructural coarsening both lead to ‘anomalous’ changes in microcantilever curvature since the curvature gradually increases or decreases away from the equilibrium curvature of the underlying Si. The inelastic behavior of the Au film is shown to depend on annealing temperature through changes in initial film stress after thermo-elastic cooling and degree of recovery.