12013-56-8Relevant academic research and scientific papers
Thermodynamic stabilities of intermediate phases in the Ca-Si system
Brutti,Ciccioli,Balducci,Gigli,Manfrinetti,Napoletano
, p. 525 - 531 (2001)
Vaporization thermodynamics in the binary system calcium-silicon has been studied by Knudsen effusion-mass spectrometry and vacuum microbalance techniques. The equilibrium partial pressure of Ca(g) over the two-phase regions in the composition range 20-75
Radical-Induced Hydrosilylation Reactions for the Functionalization of Two-Dimensional Hydride Terminated Silicon Nanosheets
Helbich, Tobias,Lyuleeva, Alina,H?hlein, Ignaz M. D.,Marx, Philipp,Scherf, Lavinia M.,Kehrle, Julian,F?ssler, Thomas F.,Lugli, Paolo,Rieger, Bernhard
, p. 6194 - 6198 (2016)
Herein we present the functionalization of freestanding silicon nanosheets (SiNSs) by radical-induced hydrosilylation reactions. An efficient hydrosilylation of Si-H terminated SiNSs can be achieved by thermal initiation or the addition of diazonium salts with a variety of alkene or alkyne derivatives. The radical-induced hydrosilylation is applicable for a wide variety of substrates with different functionalities, improving the stability and dispersibility of the functional SiNSs in organic solvents and potentially opening up new fields of application for these hybrid materials.
Dumbbells of five-connected silicon atoms and superconductivity in the binary silicides MSi3 (M = Ca, Y, Lu)
Schwarz, Ulrich,Wosylus, Aron,Rosner, Helge,Schnelle, Walter,Ormeci, Alim,Meier, Katrin,Baranov, Alexey,Nicklas, Michael,Leipe, Susann,Mueller, Carola J.,Grin, Yuri
, p. 13558 - 13561 (2012)
The new metastable binary silicides MSi3 (M = Ca, Y, Lu) have been synthesized by high-pressure, high-temperature reactions at pressures between 12(2) and 15(2) GPa and temperatures from 900(100) to 1400(150) K. The atomic patterns comprise int
Phase selection during calcium silicide formation for layered and powder growth
Wen, Cuilian,Kato, Akihiko,Nonomura, Tomomi,Tatsuoka, Hirokazu
, p. 4583 - 4587 (2011)
Phase selection during Ca silicide formation was discussed using the chemical potential and the effective heat of formation (ΔH′) models. The compositional analyses of Ca silicides were experimentally carried out in detail for both the layered and powder
High-pressure synthesis and superconductivity of the laves phase compound Ca(Al,Si)2 composed of truncated tetrahedral cages Ca at (Al,Si) 12
Tanaka, Masashi,Zhang, Shuai,Inumaru, Kei,Yamanaka, Shoji
, p. 6039 - 6045 (2013)
The Zintl compound CaAl2Si2 peritectically decomposes to a new ternary cubic Laves phase Ca(Al,Si)2 and an Al-Si eutectic at temperatures above 750 C under a pressure of 13 GPa. The ternary Laves phase compound can also be prepared as solid solutions Ca(Al1-xSi x)2 (0.35 ≤ x ≤ 0.75) directly from the ternary mixtures under high-pressure and high-temperature conditions. The cubic Laves phase structure can be regarded as a type of clathrate compound composed of face-sharing truncated tetrahedral cages with Ca atoms at the center, Ca at Al,Si)12. The compound with a stoichiometric composition CaAlSi exhibits superconductivity with a transition temperature of 2.6 K. This is the first superconducting Laves phase compound composed solely of commonly found elements.
High pressure synthesis and crystal structure of a ternary superconductor Ca2Al3Si4 containing layer structured calcium sub-network isomorphous with black phosphorus
Tanaka, Masashi,Zhang, Shuai,Tanaka, Yuki,Inumaru, Kei,Yamanaka, Shoji
, p. 445 - 451 (2013)
The Zintl compound CaAl2Si2 is peritectically decomposed to a mixture of Ca2Al3Si4 and aluminum metal at temperatures above 600 °C under a pressure of 5 GPa. The new ternary compound Ca2Al3Sl4 crystalizes with the space group Cmc21 and the lattice parameters a=5.8846(8), b=14.973(1), and c=7.7966(5) A. The structure is composed of aluminum silicide framework [Al3Si4] and layer structured [Ca 2] network interpenetrating with each other. The electron probe microanalysis (EPMA) shows the formation of solid solutions Ca 2Al3-xSi4+x (x2] sub-network is isomorphous with black phosphorus. The new ternary compound shows superconductivity with a transition temperature (T c) of 6.4 K. The band structure calculation suggests that the superconductivity should occur through the conduction bands mainly composed of 3p orbitals of the aluminum silicide framework.
Low temperature properties of calcium mono- and disilicides
Affronte,Laborde,Olcese,Palenzona
, p. 68 - 73 (1998)
Low temperature electronic and lattice properties of polycrystalline CaSi and CaSi2 have been studied by means of specific heat, resistivity, Hall effect and magnetoresistance measurements. Although these metals have comparable density of electronic states at the Fermi level (0.42 states/eV atom and 0.19 states/eV atom for CaSi and CaSi2 respectively) the resistivity of CaSi2 (ρ273 K = 33.2 μΩ cm) is almost one order of magnitude lower than that of CaSi (ρ273 K = 282 μΩ cm). The analysis of magnetotransport properties suggests that both these materials are compensated metals and the estimated density of carriers is one order of magnitude higher for CaSi2 than for CaSi. In agreement with electronic band structure calculations we concluded that electrons of the Ca d-band play a dominant role for the charge transport. The Debye temperature estimated from different experiments is higher for CaSi2 than for CaSi and this confirms that the Ca-Si interaction increases as the Si concentration increases.
Heat capacity and thermodynamic properties of some Ca silicides
Canepa,Napoletano,Manfrinetti,Palenzona
, p. 20 - 23 (2000)
The heat capacities of three Ca compounds, namely CaSi2, Ca3Si4 and Ca14Si19 were measured in the 3-300 K temperature range by adiabatic calorimetry. No thermal anomalies were found in the whole temperature range. In the three Ca silicides, from an analysis of the low temperature data (Ta power law lower than three in the lattice heat capacity behaviour was observed and tentatively ascribed to the layered structure of the compounds, in agreement with structural informations. From heat capacity data the thermodynamic functions entropy, enthalpy and Gibbs energy were calculated at 298 K.
Effect of electrolysis potential on reduction of solid silicon dioxide in molten CaCl2
Yasuda, Kouji,Nohira, Toshiyuki,Ito, Yasuhiko
, p. 443 - 447 (2005)
Electrochemical reduction of solid SiO2 by using a contacting electrode method was investigated in molten CaCl2 at 1123 K. The samples were prepared by potentiostatic electrolysis at 0.35-1.30 V (vs. Ca 2+/Ca) for 1 h. From the results of XRD, SEM and EPMA, it was confirmed that SiO2 was electrochemically reduced to Si at 1.25 V or more negative potential, which agreed with the thermodynamic calculation. The current-time curves during electrolysis and the cross-sectional SEM measurements of the samples clearly showed that reduction rate is higher at more negative potential. In addition, Si-Ca alloy formation was confirmed at 0.35 V.
Structural, microstructural and thermal characterization of layer-structured CaSi2 produced by clean combustion synthesis method
Kamali, Ali Reza,Qin, Yong
, (2021/08/17)
Layer-structured calcium silicide (CaSi2) is prepared using a fast and clean combustion synthesis (CS) method, employing silica as the silicon source. The CS process was characterized by the occurrence of an ignition reaction at 510 °C, leading to the formation of CaO, CaSi2, Ca14Si19, and Ca3SiO5 which is converted into CaSi2 with minor amounts of Si after an acid treatment. The mechanism involved in the CS process is discussed. The structure and microstructure of the CS-CaSi2 is characterized and compared with the commercial CaSi2, and the outcomes are discussed based on the Ca-Si binary phase diagram. In comparison with the latter, the CS-CaSi2 has a considerably greater purity, with loosely stacked structure, providing a surface area of around 43 m2 g?1. The thermal analysis of the CS-CaSi2 is conducted under high purity argon and air flow of 100 mL min?1, comprising differential scanning calorimetry (DSC) and thermal gravimetric (TG) analysis. The analysis conducted under argon provides evidence for the occurrence of the melting event at 1037 °C. Under air, the material is almost stable below 800 °C, while the oxidation is detected at higher temperatures. The oxidation peak of the material is realized from the corresponding DSC thermogram to take place at 1028 °C. The oxidation event is suggested to occur through two stages. At the first stage (T 2. The second oxidation stage taking place at higher temperatures can be related to the oxidation of Si, with a lower rate. The Li-storage performances of the commercial CaSi2 and CS-CaSi2 are evaluated.
