Optimal Magnetic Graphite Heater Design for Impurity Control in Single-Crystal Si Grower Using Crystal Growth Simulation

In this paper, we report a successfully modified single-crystal Si growth furnace for impurity control. Four types of arbitrary magnetic heater (AMGH) systems with 3, 4, 5, and poly parts were designed in a coil shape and analyzed using crystal growth simulation. The concentration of oxygen impurities in single-crystal Si ingots was compared among the designed AMGHs and a normal graphite heater (NGH). The designed AMGHs were confirmed to be able to control turbulence and convection in a molten state, which created a vortex that influenced the oxygen direction near the melt–crystal interface. It was confirmed that replacing NGH with AMGHs resulted in a reduction in the average oxygen concentration at the Si melt–crystal interface by approximately 4.8%.

Synergistic effect of titanium, boron and oxygen on large-size single-crystal diamond growth at high pressure and high temperature

In this study, the synergistic impact of boron, oxygen and titanium on growing large single-crystal diamonds was studied using different concentrations of B2O3 in a solvent-carbon system under 5.5-5.7 GPa and 1300-1500 ℃. The study found that it was difficult for boron atoms to enter the crystal when boron and oxygen impurities were doped using B2O3 without the addition of Ti. However, a high boron content was achieved in the doped diamonds that were synthesised with the addition of Ti. Additionally, boron-oxygen complexes were found on the surface of the crystal, and oxygen-related impurities appeared in the crystal interior when Ti added in the FeNi-C system. The results showed that the introduction of Ti in the synthesis cavity could effectively control the amount of boron and oxygen in the crystal. This not only has important scientific significance for understanding the synergistic influence of boron, oxygen and titanium on the growth of diamond in the earth, but also for the preparation of high-concentration boron or oxygen containing semiconductor diamond technologies.

Synthesis of a Composite Alloy Based on Ore Concentrate and Oxide Compounds

The conditions for the synthesis of Al-Cr-W alloys during the aluminothermic reduction of a mineral tungsten concentrate - scheelite were considered. The alloys were identified as an aluminum matrix by the methods of elemental and X-ray phase analyzes. It is shown that the alloy synthesized from scheelite concentrate contains small amounts of iron and oxygen impurities (1.2 wt. %). It has been established that the alloys have a composite structure: inclusions of continuously solid solutions based on chromium and tungsten, as well as chromium aluminides Al3(Cr, W, Fe)2, which have increased microhardness values (12.9 GPa) are distributed in the aluminum matrix.

Control of Oxygen Impurities in a Continuous-Feeding Czochralski-Silicon Crystal Growth by the Double-Crucible Method

The continuous-feeding Czochralski method is a cost-effective method to grow single silicon crystals. An inner crucible is used to prevent the un-melted silicon feedstock from transferring to the melt-crystal interface in this method. A series of global simulations were carried out to investigate the impact of the inner crucible on the oxygen impurity distributions at the melt-crystal interface. The results indicate that, the inner crucible plays a more important role in affecting the O concentration at the melt-crystal interface than the outer crucible. It can prevent the oxygen impurities from being transported from the outer crucible wall effectively. Meanwhile, it also introduces as a new source of oxygen impurity in the melt, likely resulting in a high oxygen concentration zone under the melt-crystal interface. We proposed to enlarge the inner crucible diameter so that the oxygen concentration at the melt-crystal interface can be controlled at low levels.

Isomalk-3 and Isomalk-3R Technologies for Production of Individual Light Paraffins as the Feed for Petrochemical Facilities

The article discusses the new environmentally friendly catalytic technologies for processing butane cut, developed by SIE Neftehim LLC, giving wide opportunities for involving LPG in production of commercial value-added products. Development of petrochemical industry has created a demand for technologies and catalysts that enhance the economic efficiency of petrochemical products’ manufacturing and expand the feed base of petrochemical facilities without involving primary processing feeds. As the environmentally safe and economically effective solution, SIE Neftehim, LLC offers Isomalk-3 technology to produce maximum amount of isobutane, and Isomalk-3R technology to produce maximum amount of n-butane from isobutane cut. Application of Isomalk-3R technology expands the feed base for ethylene production due to isomerization of isobutane by-product to n-butane. N-butane is a valuable feed for pyrolysis units, providing high yields of ethylene, propylene, and n-butene used for polymer production. In turn, obtaining additional amounts of isobutane is possible due to application of n-butane to isobutane catalytic isomerization technology Isomalk-3. Isobutane cut produced in Isomalk-3 technology is notable for its high purity: the isobutane content may exceed 99 wt.%, it has no sulfur, nitrogen, chlorine, and oxygen impurities. Isobutane is in demand as the feed for production of alkylate, butyl rubber, oxygenates (MTBE and ETBE), isooctane. Isomalk-3 and Isomalk-3R processes do not require injection of chlorinating reagents, and the highly active catalytic system is resistant to poisons and impurities. Isomalk-3 and Isomalk-3R process designs are very similar, which allows integrating two units into one for alternate production of n-butane and isobutane.