Phosphidosilicates

The phosphidosilicates or phosphosilicides are inorganic compounds containing silicon bonded to phosphorus and one or more other kinds of elements. In the phosphosilicates each silicon atom is surrounded by four phosphorus atoms in a tetrahedron. The triphosphosilicates have a SiP₃ unit, that can be a planar triangle like carbonate CO₃. The phosphorus atoms can be shared to form different patterns e.g. [Si₂P₆]¹⁰⁻ which forms pairs, and [Si₃P₇]³⁻ which contains two-dimensional double layer sheets.^[1] [SiP₄]⁸⁻ with isolated tetrahedra, and [SiP₂]²⁻ with a three dimensional network with shared tetrahedron corners.^[2] SiP clusters can be joined, not only by sharing a P atom, but also by way of a P-P bond. This does not happen with nitridosilicates or plain silicates.

The phosphidosilicates can be considered as a subclass of the pnictogenidosilicates, where P can be substituted by N (nitridosilicates), As, or Sb. Also Silicon can be substituted to form other series of compounds by replacement with other +4 oxidation state atoms like germanium, tin, titanium or even tantalum.

List

formula	name	crystal system	space group	unit cell Å	form	MW	density	properties	references
Li2SiP2		tetragonal	I41/acd	a=12.111 Å, c=18.658 Å, Z=32 V=2732.6	4 SiP4 tetrahedra are linked together to form a supertetrahedron. Supertetrahedrons are linked together by corner sharing.	103.91	2.02		[2][3]
LiSi2P3			I41/a	a=18.4757  Å, c=35.0982  Å, Z=100	Interpenetrating networks of bridged supertetrahedra				[3]
Li3Si3P7		monoclinic	P21/m	a = 6.3356 Å, b = 7.2198 Å, c = 10.6176 Å, β = 102.941°, Z = 2				grey	[1]
Li5SiP3		Cubic	Fm3m	a=5.84 Z=1.33	SiP4 tetrahedra, but some Si replace by Li				[4]
Li10Si2P6			P21/n	a = 7.2051 Å, b = 6.5808 Å, c = 11.6405 Å, β = 90.580°, Z = 4	contains Si2P6 units with two Si atoms linked by two P atoms			also known by Li5SiP3	[1]
Li8SiP4	lithium orthophosphidosilicate	cubic	Pa3	a=11.6784 Z=8 V=1592.76		207.49	1.73	orange red	[2]
Li14SiP6		Cubic	Fm3m	a=5.9393 Z=4	SiP4 tetrahedra, but some Si replace by Li		1.644		[5]
Na19Si13P25		triclinic	P1	a =13.3550 Å, b =15.3909 Å, c =15.4609 Å, α =118.05°, β =111.71°, γ =93.05°, Z =2	T3 supertetrahedra			sodium ion conductor	[6]
Na23Si19P33		monoclinic	C2/c	a =28.4985 Å, b =16.3175 Å, c = 13.8732 Å, β =102.35°, Z =4	solely T3 supertetrahedra			sodium ion conductor	[6]
Na23Si28P45		monoclinic	P21/c	a =19.1630 Å, b =23.4038 Å, c = 19.0220 Å, β =104.30°, Z =4	T3 and T4 supertetrahedra			sodium ion conductor	[6]
Na23Si37P57		monoclinic	C2/c	a =34.1017 Å, b =16.5140 Å, c = 19.5764 Å, β =111.53°, Z =4	solely T4 supertetrahedra			sodium ion conductor	[6]
LT-NaSi2P3		tetragonal	I41/a	a =19.5431 Å, c = 34.5317 Å, Z =100	fused T4 and T5 supertetrahedra			sodium ion conductor	[6]
HT-NaSi2P3		tetragonal	I41/acd	a =20.8976 Å, c = 40.081 Å, Z =128	solely fused T5 supertetrahedra			sodium ion conductor	[6]
Na2SiP2	disodium diphosphidosilicate	Tetrahedral	Pccn	a = 12.7929 Å, b = 22.3109 Å, c = 6.0522 Å and Z = 16	edge‐shared SiP4 tetrahedra with 1 width chains			dark red 0.43 eV	[7]
Na5SiP3		monoclinic	P21/c	Z=4 a= 7.352 Å, b= 7.957, Å c= 13.164 Å, α=90.757°			2.06	also known by Na10Si2P6 band gap 1.292 eV	[8][9]
Na3K2SiP3	trisodium dipotassium triphosphidosilicate	Orthorhombic	Pnma	a=14.580 b=4.750 c= 13.020 V=901.7 Z=4	SiP3 triangles				[10]
Na4Ca2SiP4		hexagonal	P63mc	a=913 c=617 V=151.5	SiP4 tetrahedra		2.128		[11]
Na4Sr2SiP4		hexagonal	P63mc	a=9.283 c=7.295 V=164			2.498		[11]
Na4Eu2SiP4		hexagonal	P63mc	a=9.251 c=7.198 V=160.7			3.226		[11]
MgSiP2		tetragonal	I42d	a=5.721 c=10.095				orange yellow; semiconductor band gap 2.24 eV; decomposed by water or acid	[12]
AlSiP3		orthorhombic	Pmnb	a = 9.872, b = 5.861, c = 6.088, Z=4	P-P bonds			black	[13][14]
K2SiP2		orthorhombic	Ibam	a = 12.926, b = 6.867, c= 6.107, Z=4, V=542.07	one dimensional chain		2.061		[13][15]
KSi2P3		monoclinic	C2/c	a=10.1327 Å, b=10.1382 Å, c=21.118 Å, β=96.88°, Z=8 V=2153.8Å3	solely fused T3 supertetrahedra		2.321	dark red, band gap 1.72 eV	[8]
KSi2P3		tetragonal	I41/acd	a =21.922 Å, c = 39.868 Å, Z =128	solely fused T5 supertetrahedra			potassium ion conductor	[16][17]
Ca2Si2P4			P41212	a = 7.173, c = 26.295				band gap 0.984 eV	[18]
Ca3Si2P4		monoclinic		a = 7.073 Å, b = 17.210 Å, c = 6.918 Å, β = 111.791°				band gap 0.826 eV	[18]
Ca3Si8P14		monoclinic	P21/c	a = 12.138 Å, b = 13.476 Å, c = 6.2176 Å, β = 90.934°				band gap 0.829 eV	[18]
Ca4SiP4		cubic		a=11.875 V=1675			2.48		[19]
MnSiP2		tetrahedral	I 4 2 d	a 5.5823 c 10.230				metallic; SHG 32.8 pm/V	[20]
Fe5SiP				a=6.766 c=12.456 V=493.8 Z=6			6.83		[21]
CoSi3P3		monoclinic	P21	(pseudo orthrhombic) a = 5.899, b = 5.703, c = 12.736, β = 90.00° Z=4				resistivity 0.62 Ohm cm band gap 0.12 eV	[22]
NiSi3P4		tetragonal	I42m	a = 5.1598 c =10.350 Z = 2			3.22		[13][23]
NiSi2P3			Imm2	a = 3.505, b = 11.071, c = 5.307, Z = 2					[13][24]
FeSi4P4				a = 4.876, b = 5.545, c = 6.064, α = 85.33°, β = 68.40°, γ = 70.43° Z=4 P and Si random			3.38	resistivity 0.3 Ohm cm band gap 0.15, can take in Li or Na	[13][22][25]
Cu4SiP8			I41/a	a = 12.186, c = 5.732, Z = 8	P-P bonds				[13][26]
ZnSiP2		Tetragonal	I42d	a = 5.399 Å c = 10.435 Å Z=4 V=304.173 Å3	chalcopyrite structure SiP4 and Zn4 tetrahedra	154.936	3.3 (measured)	dark red clear; red luminescent; semiconductor; band gap 2.01 eV	[13][27][28]
ZnSiP2		Cubic						over 27 GPa Superconductor Tc = 8.2K	[28]
Sr2SiP4								band gap 1.41 eV	[29]
Sr4SiP4		cubic		a=12.426 V=1919			3.48		[19]
SrSi7P10		triclinic	P1	a =6.1521 Å, b =8.0420 Å, c =8.1374 Å, α =106.854°, β =99.020°, γ =105.190°, Z =1	tetrahedral network derived from T2 supertetrahedra			band gap 1.1 eV	[30][29]
Mg2Sr3Si20P30		hexagonal	P63	a = 15.7767 c = 11.7407					[31]
MgSr3Si3P7			P31m	a = 18.7339 c = 6.1393					[31]
RhSi3P3		monoclinic	C2	a=5.525, b=7.210, c=5.522 β=118.31°, Z=2 P and Si random			4.005	black	[13][32]
RuSi4P4		triclinic	P1	a = 4.936, b = 5.634, c = 6.162, α = 85.51°, β = 68.26°, γ = 70.69° Z=1 V=150			3.74	metallic	[22][33]
RuSi4P4		triclinic	P1	a=4.9362 b=5.6326 c=6.1649 α=85.5073° β=68.2559° γ=70.6990°			3.732	dark red;band gap 1.9 eV	[34]
AgSiP2		Tetragonal	I42d	6.5275, c = 8.550, Z = 4; V = 364.3	SiP4 corner sharing	305.77	5.58	shiny black	[13]
Mg2In3Si2P7		monoclinic	P21	a 6.9375 b 6.5646 c 14.469 β 103.87° Z=2		639.7	3.458	SHG 7.1 × AgGaS2; band gap 2.21	[35]
Sn4.2Si9P16		rhombohedral	R3	a = 9.504 Å, α = 111.00°, and Z = 1				band gap 0.2	[36]
CdSiP2		tetragonal	I42d	a = 5.680 c = 10.431 Å Z=4 V=336.494 Å3	chalcopyrite structure	202.434	3.995	carmine colour; red luminescent	[13][37][38]
Cs2SiP2	Dicesium catena-diphosphidosilicate	Orthorhombic	Ibam						[13]
Cs5SiP3	Pentacesium triphosphidosilicate	Orthorhombic	Pnma	a=6.064, b=14.336, c=15.722	SiP3 planar triangles			dark metallic, air sensitive	[39]
BaSi7P10		triclinic	P1	a =6.1537 Å, b =8.0423 Å, c =8.1401 Å, α =106.863°, β =99.050°, γ =105.188°, Z =1	tetrahedral network derived from T2 supertetrahedra				[30]
Ba2SiP4		Tetragonal	I42d	a = 9.90.57 Å, c = 7.31.80 Å; Z = 4 V=718.06 Å	contains P-P bonds	426.65		band gap 1.45 eV	[40][29]
Ba2SiP4		Orthorhombic	Pnma	a=12.3710 b=4.6296 c=7.9783 Z= 8 V=1443.9	chains of Si-P-Si	426.65	3.925	black band gap 1.7 eV	[41]
Ba2Si3P6								band gap 1.88	[29]
Ba3Si4P6		monoclinic	P21/m	a=1153.7 Å, b=728.1 Å, c=752.7 Å, β = 99.41° V=623.76 Z=2	Zintl compound P-P and Si-Si bonds		3.78	black metallic	[13][42]
Ba4SiP4		cubic		a=13.023 V=2219			4.22		[13][19]
BaCuSi2P3		monoclinic		a=4.5659 b=10.1726 c=6.8236 β = 109.311 V=299.10	layered				[43]
LaSiP3		monoclinic		a = 5.972, b = 25.255, c = 4.168, β= 135.71°, Z = 4	two dimensional network of boat-shaped six-membered rings of Si-P-Si-P-Si-P				[44]
LaSi2P6			Cmc21	a=10.129 b=28.17 c=10.374 Z=16	P-P bonds	380.9	3.42	grey	[13][45]
La2Mg3SiP6		orthorhombic	Pnma	a=11.421 b=8.213 c=10.677 Z=4					[46]
CeSiP3		orthorhombic	Pn21a	a = 5.861, b= 5.712, c= 25.295 V=846.7 Å3, Z=8	P-P bonds	261.13	4.095		[13][47]
CeSi2P6			Cmc21	a= 10.118 b= 28.03 c= 10.311 Z= 16, V=2.924	P-P bonds	382.1	3.47	grey	[45]
Ce2Mg3SiP6		orthorhombic	Pnma	a=11.356 b=8.188 c=10.564 Z=4					[46]
PrSi2P6			Cmc21	a= 10.085 b= 27.95 c= 10.267 Z= 16, V=2.895 nm3	P-P bonds			grey	[45]
NdSi2P6			Cmc21	a= 10.031,b= 27.81,c= 10.245,Z= 16, V=2.857	P-P bonds			grey	[45]
ReSi4P4
OsSi4P4		triclinic	P1	a = 4.948, b = 5.620, c = 6.175, α = 85.65, β = 68.36, γ = 70.89, Z=4 V=150.6			4.72	metallic	[22][33]
IrSi3P3		monoclinic	C2	a=6.577, b=7.229, c=5.484 β=117.91°, Z=2				black	[22][32]
IrSi3P3		monoclinic	Cm	a=6.5895 b=7.2470 c=5.4916 β=117.892				dark red;band gap 1.8 eV	[34]
PtSi2P2		monoclinic	P21	a=6.025 Å, b=9.468 Å, c=11.913 Å, β=102.91°,Z=8, V=552.2			6.327	high resistance metallic,shiny black, air sensitive	[48]
PtSi3P2		triclinic	P1	a=4.840 Å,b=5.482 Å,c=8.052 Å, α=91.57°, β=93.52°, γ=108.14°, Z=2 V=202.3			5.656	shiny black	[48]
AuSiP		rhombohedral	R3m	a=3.459, c = 17.200, Z = 3; V = 178.19		256.03	7.16	shiny black	[13]
Th2SiP5		triclinic		a=4.04.3 Å, b=4.04.5 Å, c = 10.279 pm, α = 90.09°, β = 90.09° and γ = 89.50°, Z = 1	chains of corner linked SiP4 tetrahedra, and square net of P				[44]