1305-99-3Relevant articles and documents
Thermodynamic properties of
Zaitsev, A. I.,Korolyov, N. V.,Mogutnov, B. M.
, p. 11 - 23 (1991)
A Knudsen-effusion technique in combination with a mass-spectral analysis of the vapour phase has been applied to study thermodynamic properties of alloys (0.5 under x under 1) over the temperature range 650 K to 1537 K.The compound CaP was found to be unstable and to decompose at low temperatures into Ca3P2 and gaseous phosphorus.Evaporation of the phosphide Ca3P2 was followed by congruent decomposition.The standard molar Gibbs energy of formation of Ca3P2 from red phosphorus and solid calcium has been expressed by the equation: .Thermodynamic functions of (1) have been estimated with help of ΔfGdegm(Ca3P2) values and the coordinates of a point on the line of the two-phase equilibrium (Ca3P2 + 1).It has been shown that the liquid solution can be described by the ideal-associated-solution model if complexes of Ca3P2 type are assumed to exist.
Metallicity of Ca2Cu6P5 with single and double copper-pnictide layers
Li, Li,Parker, David,Chi, Miaofang,Tsoi, Georgiy M.,Vohra, Yogesh K.,Sefat, Athena S.
, p. 334 - 339 (2016)
We report thermodynamic and transport properties, and also theoretical calculations, for Cu-based compound Ca2Cu6P5 and compare with CaCu2-δP2. Both materials have layers of edge-sharing copper pnictide tetrahedral CuP4, similar to Fe-As and Fe-Se layers (with FeAs4, FeSe4) in the iron-based superconductors. Despite the presence of this similar transition-metal pnictide layer, we find that both Ca2Cu6P5 and CaCu2-δP2 have temperature-independent magnetic susceptibility and show metallic behavior with no evidence of either magnetic ordering or superconductivity down to 1.8 K CaCu2-δP2 is slightly off-stoichiometric, with δ = 0.14. Theoretical calculations suggest that unlike Fe 3d-based magnetic materials with a large density of states (DOS) at the Fermi surface, Cu have comparatively low DOS, with the majority of the 3d spectral weight located well below Fermi level. The room-temperature resistivity value of Ca2Cu6P5 is only 9 μΩ-cm, due to a substantial plasma frequency and an inferred electron-phonon coupling λ of 0.073 (significantly smaller than that of metallic Cu). Also, microscopy result shows that Cu-Cu distance along the c-axis within the double layers can be very short (2.5 ?), even shorter than metallic elemental copper bond (2.56 ?). The value of dρ/dT for CaCu2-δP2 at 300 K is approximately three times larger than in Ca2Cu6P5, which suggests the likelihood of stronger electron-phonon coupling. This study shows that the details of Cu-P layers and bonding are important for their transport characteristics. In addition, it emphasizes the remarkable character of the DOS of '122' iron-based materials, despite much structural similarities.
Structural Phase Transitions and Superconductivity Induced in Antiperovskite Phosphide CaPd3P
Eisaki, Hiroshi,Fujihisa, Hiroshi,Gotoh, Yoshito,Hirose, Hishiro T.,Ishida, Shigeyuki,Iyo, Akira,Kawashima, Kenji,Ninomiya, Hiroki,Terashima, Taichi,Yoshida, Yoshiyuki
, p. 12397 - 12403 (2020/09/15)
In this study, we succeeded in synthesizing new antiperovskite phosphides MPd3P (M = Ca, Sr, Ba) and discovered the appearance of a superconducting phase (0.17 ≤ x ≤ 0.55) in a solid solution (Ca1-xSrx)Pd3P. Three perovskite-related crystal structures were identified in (Ca1-xSrx)Pd3P, and a phase diagram was built on the basis of experimental results. The first phase transition from centrosymmetric (Pnma) to noncentrosymmetric orthorhombic (Aba2) occurred in CaPd3P near room temperature. The phase transition temperature decreased as Ca2+ was replaced with a larger-sized isovalent Sr2+. Bulk superconductivity at a critical temperature (Tc) of approximately 3.5 K was observed in a range of x = 0.17-0.55; this was associated with the centrosymmetric orthorhombic phase. Thereafter, a noncentrosymmetric tetragonal phase (I41md) remained stable for 0.6 ≤ x ≤ 1.0, and superconductivity was significantly suppressed as samples with x = 0.75 and 1.0 showed Tc values as low as 0.32 K and 57 mK, respectively. For further substitution with a larger-sized isovalent Ba2+, namely, (Sr1-yBay)Pd3P, the tetragonal phase continued throughout the composition range. BaPd3P no longer showed superconductivity down to 20 mK. Since the inversion symmetry of structure and superconductivity can be precisely controlled in (Ca1-xSrx)Pd3P, this material may offer a unique opportunity to study the relationship between inversion symmetry and superconductivity.
Contributions to the Chemistry of Phosphorus. 235. On the Preparation ofLarger Amounts of Diphosphane(4) in the Laboratory
Baudler, M.,Staendeke, H.,Borgardt, M.,Strabel, H.,Dobbers, J.,et al.
, (2008/10/08)
The preparation of several hundred grammes of diphosphane(4) by hydrolysis of calcium phosphide in a semicontinuous process as well as the handling of larger amounts of this compound are reported. In comparison with earlier results [12], the yield has been raised by 37 percent with simultaneous increase of the accessible total amount. The white solid which is formed in the preparation and purification of diphosphane(4) is not, as was believed in earlier work [25,8], triphosphane(5) or another, novelphosphorus hydride but is rather a clathrate compound of diphosphane(4) or the phosphanes PnHn+2 (n=2-4) and water, respectively.
