Titanium transition temperature

Special Alloys. AHoys of tin with the rater metals, such as niobium, titanium, and 2kconium, have been developed. The single-phase alloy Nb Sn [12035-04-0] has the highest transition temperature of any known superconductor (18 K) and appears to keep its superconductivity in magnetic... 

Titanium alloyed with niobium exhibits superconductivity, and a lack of electrical resistance below 10 K. Composition ranges from 25 to 50 wt % Ti. These alloys are P-phase alloys having superconducting transitional temperatures at ca 10 K. Thek use is of interest for power generation, propulsion devices, fusion research, and electronic devices (52). 

Figure 8.6 shows the definition of transition temperature Tc and transition width Wc. To remark how the purity of the material and the magnetic field influence the two parameters, we will report hereafter the measurements of the superconducting transition of titanium samples of different purity and in the presence of different magnetic fields. The transitions of four Ti samples, whose characteristics are reported in Table 8.12, are shown in Fig. 8.7 where a change of only 0.2% in purity dramatically moves both the transition... 

The normal spinel Li[Ti2]04 is a metallic oxide with a superconducting transition temperature of 13.7 K. The nominal formula is Li+[Ti3+Ti4+]04, in which the Li+ ions occupy the tetrahedral sites while the octahedral sites contain titanium with an average charge Ti3 5+, although as the material is metallic at room temperature the electrons are delocalized in a partly filled 3d band. 

A mixture of dimethyl terephthalate (0.495 mol), 5-sodiosulfoisophthalic acid (0.005 mol), ethylene glycol (1.0 mole), and titanium tetraisopropoxide (100 ppm) was placed in a 500-ml flask equipped with an inlet for nitrogen, a metal stirrer, and a short distillation column. The flask was placed in a heated metal bath and the contents heated at 185°C for 2 hours, 200°C for 2 hours, and then up to 250°C under high vacuum for 2 hours. The temperature was finally increased to 270°C and a vacuum of 0.45 mmHg maintained for for 2 hours to remove unreacted diol. A high melt viscosity polymer was obtained with a glass transition temperature of 77°C with an inherent viscosity of 0.77 dl/g. 

XRD analysis of the xerogels obtained by drying pure titanium dioxide sol at 70°C showed the presence of the nanocrystalline anatase phase [109]. Thermal treatment of this xerogel resulted in the growth of anatase crystallites up to 400°C. The anatase-to-rutile transformation began to occur at 450-500°C. This process was practically completed at 700°C, and only rutile phase existed at rcaic > 700°C. This feature of Ti02 xerogels is typical and well known (see, for example, [109]). Thus, it can be concluded that anatase-rutile transition temperature of nanosized particles is considerably lower than that of the... 

The results of XRD show that the anatase phase is formed at a temperature of 330°C for the pure titanium dioxide, while rutile phase is formed when the calcination temperature approached 630°C, indicating the beginning of the transformation from anatase to rutile. The anatase peaks in the XRD pattern disappears during the heat treatment of bare titanium dioxide at 700°C for Ih, suggesting the end of the transformation of anatase to rutile. The evolution of both anatase and rutile starts at higher temperature for silicon doped samples. However, the transition temperature of anatase to rutile progressively elevates when the silicon content is increased. Figure 1 shows the 29 diffraction scans for some of the samples annealed at 1000°C for Ih in air. It can be seen that the phase transition temperature... 

Nitinol is an alloy of nickel and titanium that has the austentite phase structure. Each nickel atom is at the center of a cube of titanium, and a titanium atom is at the center of each cube of nickel atoms. If nitinol is shaped into a straight wire, heated, and cooled past the transition temperature, it converts into the martensite phase. Now its structure allows the nitinol to be bent by an external stress. If the wire is heated, the stress is released and it reverts back to its initial shape. 

Crucibles of titanium nitride and zirconium nitride are utilized for the melting of lanthanum alloys. ZrN, HfN and TaN are also used as electrodes in electronic valves. Niobium and zirconium nitrides could be used as superconductors due to their relatively high superconductor transition temperatures of 16.8 and 10 K respectively. 

Medium-c/5 lithium-polybutadiene was first developed by Firestone Tire and Rubber Company in 1955 [86]. Solution polymerization using anionic catalysts is usually based on butyllithium. Alkyllithium initiation does not have the high stereospecificity of the coordination catalysts based on titanium, cobalt, nickel, or neodymium compounds. Polymerization in aliphatic hydrocarbon solvents such as hexane or cyclohexane yields a polymer of about 40 % cis, 50 % trans structure with 10 % 1,2-addition. However, there is no need for higher cis content because a completely amorphous structure is desired for mbber applications the glass transition temperature is determined by the vinyl content. The vinyl content of the polybutadiene can be increased up to 90 % by addition of small amounts of polar substances such as ethers. 

Titanium micro debris lost from the tip during sonication is removed by centrifugation at 500 g for 10 min above the transition temperature (see Note 14). 

Thermomechanical processing (TMP) has first been developed in the second half of the last century for decreasing the ductile to brittle transition temperature of construction steels. It has then progressively been extended to other categories of structural metallic materials, such as titanium alloys or nickel base superalloys for aircraft forged turbine parts. More recently, investigations have been carried out to assess the possibility and advantage of TMP for ferritic and austenitic stainless steels. 

Monocyclopentadienyl complexes of titanium (CpTiXs) perform poorly as catalysts for ethylene or propylene polymerization, but in the presence of MAO, they polymerize styrene to stereo- and regioregular syndiotactic polystyrene, a crystalline material with very high melting point (273 °C) and glass transition temperature (100°C). In this case, the active polymerizing species is a complex (Figure 8). Each styrene monomer inserts in a secondary manner and the stereoregularity is maintained by the conformation of the last inserted unit (chain-end control). 

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