25275-75-6Relevant articles and documents
Ce4(Pi-xSix)3-z: A first example for the stabilization of the anti-Th3P4 type structure by substitution in the non-metal substructure
Chizhov, Pavel S.,Khasanova, Nellie R.,Baitinger, Michael,Schnelle, Walter,Prots, Yuri,Burkhardt, Ulrich,Antipov, Evgeny V.,Grin, Yuri
, p. 7210 - 7216 (2006)
A first rare-earth phosphide suicide Ce4(P1-xSi x)3-z and its analogues with La, Pr, and Nd were synthesized and characterized. The compounds crystallize in the anti-Th 3P4 structure type. The cerium compound shows a mixed occupation of the 12a site with Si and P and possesses a wide homogeneity range with respect to x and z variation. The electronic configuration of Ce, deduced from magnetic susceptibility and X-ray absorption spectroscopy data, remains 4f1 (Ce3-) independently from x and z. The cerium valence and the phase stability region are discussed employing electronic band-structure calculation and chemical bonding analysis with electron localization function. Atomic interactions are shown to remain nearly unchanged, while the change of the excess electron concentration with P/Si substitution is considered to play the main role for the stabilization of the structural motif.
Third time's the charm: Intricate non-centrosymmetric polymorphism in Ln SiP3(Ln = la and Ce) induced by distortions of phosphorus square layers
Adeyemi, Adedoyin N.,Akopov, Georgiy,Ho, Kai-Ming,Kovnir, Kirill,Lee, Shannon J.,Mark, Justin,McBride, Brennan C.,Miller, Gordon J.,Paterson, Alexander L.,Perras, Frédéric A.,Sen, Sabyasachi,Viswanathan, Gayatri,Wang, Cai-Zhuang,Won, Juyeon,Yuan, Bing,Zhang, Feng
, p. 6463 - 6476 (2021/05/31)
Complex polymorphic relationships in the LnSiP3 (Ln = La and Ce) family of compounds are reported. An innovative synthetic method was developed to overcome differences in the reactivities of the rare-earth metal and refractory silicon with phosphorus. Reactions of atomically mixed Ln + Si with P allowed for selective control over the reaction outcomes resulting in targeted isolation of three new polymorphs of LaSiP3 and two polymorphs of CeSiP3. In situ X-ray diffraction studies revealed that the developed method bypasses formation of the thermodynamic dead-end, the binary SiP. Careful re-determination of the crystal structure ruled out the previously reported ordered centrosymmetric structure of CeSiP3 and showed that the main LnSiP3 polymorphs crystallize in the non-centrosymmetric Pna21 and Aea2 space groups featuring distinct distortions of the regular P square net to yield either cis-trans 1D phosphorus chains (Pna21) or disordered-2D phosphorus layers (Aea2). The disordered 2D nature of the P layers in the Aea2 LaSiP3 polymorph was confirmed by Raman spectroscopy. A unique centrosymmetric P21/c polymorph was observed for LaSiP3 and has a completely different crystal structure lacking P layers. Consecutive polymorphic transformations at increasing temperatures for LaSiP3(Pna21 → P21/c → Aea2) were derived from optimized synthetic profiles and confirmed by a combination of phonon computations and experimental in situ and ex situ annealings. Crystal structures of the LaSiP3 polymorphs were verified via advanced solid state NMR analysis using 31P MAS and 31P{139La} double resonance techniques. A combination of phonon and electronic structure calculations, NMR T1 relaxation times, UV/Vis/NIR spectroscopy, and resistivity measurements revealed that all the reported polymorphs are semiconductors with resistivities and thermal conductivities strongly dependent on the degree of distortion of P square layers in the crystal structure. Reported here, non-centrosymmetric LnSiP3 polymorphs with tunable resistivity and thermal conductivity provide a platform for the development of novel functional materials with a wide range of applications.
RE4[P1-x(C2)x]3 (RE = La-Nd): The mixed anionic substructure formed by phosphorus and carbon
Chizhov, Pavel S.,Schnelle, Walter,Burkhardt, Ulrich,Schmidt, Marcus,Prots, Yurii,Antipov, Evgeny V.,Grin, Yuri
, p. 1318 - 1325 (2011/01/06)
The rare-earth phosphide carbides RE4[P1-x(C 2)x]3 (RE = La, Ce, Pr, Nd) represent the first example of a mixed anionic substructure formed by phosphorus and carbon, being the first step toward the formation of the mixed inorganic P-C species. The peculiarities of the crystal structure, magnetic properties, XAS data, and quantum chemical calculation results confirm the ionic nature of the interaction beween the rare-earth cations RE and phosphorus anions, while complex interaction of π states of the C2 anions and d (and/or f) states of the RE components is indicated. Thus, despite the extensive chemical analogy between the phosphide carbides and phosphide suicides, the atomic interactions stabilizing the structural motif are slightly different.
