Synthesis, Crystal and Electronic Structure of La₂SiP₄

Abstract

La2SiP4 (mP‐28, Z=4, Wyckoff sequence e7, space group P21/c (No. 14), a=10.8230(6) Å, b=7.5208(4) Å, c=7.9189(4) Å, and β=105.389(2)°) which crystallizes in the La2CuS4 structure type is reported. Instead of isolated CuS3 triangles bridged by disulfide anions, in the crystal structure of La2SiP4, one‐dimensional zig‐zag chains composed of SiP4 tetrahedra connected by P−P bonds are present. Lanthanum cations fill the voids between the chains and are coordinated by either 9P or 8P+Si atoms. La2SiP4 is a narrow bandgap semiconductor with calculated and measured optical bandgaps of 0.35 eV and 0.85(1) eV, respectively.

Non‐Linear Optical Properties of the (RE)3CuGeS7 Family of Compounds

“…Details of the arcmelting procedure can be found elsewhere. [12,13,[27][28][29][30] Utilization of precursor synthesis for such quaternary sulfides is discussed more in depth in [12] and compared to synthesis from elements and binary sulfides for select compositions. Phase compositions of the precursor materials can be found in Table 2.…”

Third time's the charm: intricate non-centrosymmetric polymorphism in LnSiP3 (Ln = La and Ce) induced by distortions of phosphorus square layers

“…Interphosphorus bonds that connect neighboring tetrahedra have also been observed in the polymorphs of Ba2SiP4 and La2SiP4. 8,9,20,29 In particular, tetragonal AE2SiP4 (AE = Sr, Eu, Ba) involves single tetrahedra bonded by P-P bonds to form a 3D framework, 8,9,20 With the compounds reported here, as well as LaSi2P6 and La2SiP4, 29 3 out of 5 compounds in the La-Si-P phase space are non-centrosymmetric (NCS). This high abundance of NCS structures in a single system is not observed in binary metal pnictides or silicides, where the amount of NCS compounds is less than 10%.…”

“…Long time annealing of the Aea2 polymorph at temperatures above 1000 o C resulted in the decomposition of LaSiP3 and formation of yet another ternary compound, La2SiP4. 29 This indicated metastable nature of the Aea2 LaSiP3 polymorph.…”

“…Open The overall shape of the DOS for monoclinic LaSiP3 resembles that of La2SiP4. 29 La-P orbital mixing in the upper region of the valence band is notable and is expected to strongly influence charge transport properties. For example, replacement of Ba with La in the clathrate La2Ba6Cu16P30 with similar La/P orbital mixing resulted in a an order of magnitude increase in hole mobility.…”

Synthesis-enabled exploration of chiral and polar multivalent quaternary sulfides

“…We have demonstrated this approach for several ternary metal pnictides, where a metal–tetrel precursor ( e.g. , LaSi) was made by arc-melting and reacted with a volatile pnictogen (P or As) at synthetic temperatures of 600–1050 °C, forming stoichiometric products such as: LaSiP 3 , 6 La 2 SiP 4 , 7 AuSiAs, 8 RuSi 4 P 4 , and IrSi 3 P 3 . 9 …”