Vibrational spectroscopy of GdCr3(BO3)4: Quantitative separation of crystalline phases

This work is devoted to the investigation of GdCr3(BO3)4 crystals by the method of infrared spectroscopy. Incongruently melting borate GdCr3(BO3)4 was obtained as a result of spontaneous crystallization. Crystal structures were identified by the method of infrared spectroscopy. Ab initio calculations in the frame of density functional theory enabled us to separate modes belonging to the R32 and C2/c phases and to estimate the ratio of these phases in GdCr3(BO3)4 crystals. We have found that the content of the rhombohedral R32 (non- centrosymmetric) modification is about 85%. © Published under licence by IOP Publishing Ltd

Phase transitions and exchange interactions in the SmCr3(BO3)4 crystal

© The Authors, published by EDP Sciences.Spectroscopic investigation and specific heat and magnetic susceptibility measurements of SmCr3(BO3)4 crystals were performed. The spectra of the Sm3+ and Cr3+ ions in samarium chromium borate were calculated and parameters of the exchange interactions between the nearest chromium ions, chromium and samarium ions were determined. Three phase transitions were observed at the temperatures T1= 7.8 ± 0.5 ?, T2 = 6.7 ± 0.5 ?, and T3 = 4.3 ± 0.2 ?, their nature is discussed. The crystal structures with different space symmetry groups R32 and C2/c were found to coexist in SmCr3(BO3)4 single crystal

Phase transitions and exchange interactions in the SmCr3(BO3)4 crystal

© The Authors, published by EDP Sciences. Spectroscopic investigation and specific heat and magnetic susceptibility measurements of SmCr 3 (BO 3 ) 4 crystals were performed. The spectra of the Sm 3+ and Cr 3+ ions in samarium chromium borate were calculated and parameters of the exchange interactions between the nearest chromium ions, chromium and samarium ions were determined. Three phase transitions were observed at the temperatures T1= 7.8 ± 0.5 ?, T 2 = 6.7 ± 0.5 ?, and T 3 = 4.3 ± 0.2 ?, their nature is discussed. The crystal structures with different space symmetry groups R32 and C2/c were found to coexist in SmCr 3 (BO 3 ) 4 single crystal

The method of expert assessments as applied to the ranking of technical solutions in the design of a tractor gearbox

The purpose of this work is to select a rational concept of the transmission of the tractor being created on the basis of an objective quantitative comprehensive assessment of the considered possible design options. The object of research is the transmission of wheeled tractors of 4 and 6-8 traction classes and forest machines based on their chassis. Making a decision on the principles of building a transmission is an important stage that requires a proper analysis of known theoretical developments, production experience, competitors' achievements, market conditions and other factors. The decision is based on the ranking of the options available for implementation of the object. It is advisable to support such a ranking with the results of an objective quantitative comprehensive assessment of the compared options. The key points in this case are the formation of a nomenclature of objective private performance indicators and the choice of a data processing method. The paper considers the issue of applying the method of expert assessments when choosing the concept of constructing a transmission and the type of transforming mechanism of a tractor. The algorithm of the method, initial data, and evaluation results are presented. The main solutions for the construction of the transmission of tractors of 4 and 6-8 traction classes have been formulated

Safe and Scalable Polyethylene Glycol-Assisted Hydrothermal Synthesis and Laser Cooling of 10%Yb³⁺:LiLuF₄ Crystals

Rare earth doped lithium fluorides are a class of materials with a wide variety of optical applications, but the hazardous reagents used in their synthesis often restrict the amount of product that can be created at one time. In this work, 10%Yb3+:LiLuF4 (Yb:LLF) crystals have been synthesized through a safe and scalable polyethylene glycol (PEG)-assisted hydrothermal method. A combination of X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and photoluminescence (PL) measurements were used to characterize the obtained materials. The influence of reaction temperature, time, fluoride source, and precursor amount on the shape and size of the Yb:LLF crystals are also discussed. Calibrated PL spectra of Yb3+ ions show laser cooling to more than 15 K below room temperature in air and 5 K in deionized water under 1020 nm diode laser excitation measured at a laser power of 50 mW

Massive sulfides of the new hydrothermal sulfide cluster Semyenov (13°31' N), Mid-Atlantic Ridge

The paper describes the ores from the new hydrothermal sulfide cluster named Semenov (13°31´N, Mid-Atlantic Ridge) composed of several hydrothermal fields. Ores from the Semyenov-1, -3 and -4 hydrothermal fields show marcasite-pyrite composition with fine-grained, colloform, and clastic textures. Ores from the Semyenov-2 hydrothermal site are characterized by isocubanite-chalcopyrite-sphalerite-wurtzite mineral assemblage with fine-grained aggregates. They are uniquely enriched in Au (up to 188 ppm) and Ag (up to 1787 ppm) and conatin visible gold associated with opal, sphalerite and chalcopyrite. Ore textural analyses of ores from the Semenov hydrothermal sulfide cluster allowed us to reveal several ore facies (cf. Maslennikov and Zaykov, 2006): subseafloor hydrothermal, seafloor hydrothermal and clastic. The veinlet-disseminated ores from the Semyenov-2 and -4 hydrothermal fields belong to the subseafloor hydrothermal facies which is formed below the seafloor simultaneously with seafloor hydrothermal processes. Seafloor hydrothermal facies, formed on the seafloor surface near the hydrothermal vents, was found at the Semenov-1 and -2 hydrothermal fields and includes fine-grained and colloform ores. Clastic facies resulted from destruction of sulfide ores occurs at the Semenov-3 field as colluvial pyrite breccia. Textural and mineralogical features of ore facies from the Semenov hydrothermal cluster are comparable with those from massive sulfide deposits of the Urals

Phase transitions and exchange interactions in the SmCr3(BO3)4 crystal

© The Authors, published by EDP Sciences.Spectroscopic investigation and specific heat and magnetic susceptibility measurements of SmCr3(BO3)4 crystals were performed. The spectra of the Sm3+ and Cr3+ ions in samarium chromium borate were calculated and parameters of the exchange interactions between the nearest chromium ions, chromium and samarium ions were determined. Three phase transitions were observed at the temperatures T1= 7.8 ± 0.5 ?, T2 = 6.7 ± 0.5 ?, and T3 = 4.3 ± 0.2 ?, their nature is discussed. The crystal structures with different space symmetry groups R32 and C2/c were found to coexist in SmCr3(BO3)4 single crystal

Phase transitions and exchange interactions in the SmCr3(BO3)4 crystal

© The Authors, published by EDP Sciences. Spectroscopic investigation and specific heat and magnetic susceptibility measurements of SmCr 3 (BO 3 ) 4 crystals were performed. The spectra of the Sm 3+ and Cr 3+ ions in samarium chromium borate were calculated and parameters of the exchange interactions between the nearest chromium ions, chromium and samarium ions were determined. Three phase transitions were observed at the temperatures T1= 7.8 ± 0.5 ?, T 2 = 6.7 ± 0.5 ?, and T 3 = 4.3 ± 0.2 ?, their nature is discussed. The crystal structures with different space symmetry groups R32 and C2/c were found to coexist in SmCr 3 (BO 3 ) 4 single crystal

Phase transitions and exchange interactions in the SmCr3(BO3)4 crystal

© The Authors, published by EDP Sciences.Spectroscopic investigation and specific heat and magnetic susceptibility measurements of SmCr3(BO3)4 crystals were performed. The spectra of the Sm3+ and Cr3+ ions in samarium chromium borate were calculated and parameters of the exchange interactions between the nearest chromium ions, chromium and samarium ions were determined. Three phase transitions were observed at the temperatures T1= 7.8 ± 0.5 ?, T2 = 6.7 ± 0.5 ?, and T3 = 4.3 ± 0.2 ?, their nature is discussed. The crystal structures with different space symmetry groups R32 and C2/c were found to coexist in SmCr3(BO3)4 single crystal