Читать книгу Encyclopedia of Glass Science, Technology, History, and Culture - Группа авторов - Страница 39

Table A.1 Coordination numbers, effective ionic radii, field strengths, and electronegativities of some cations and anions of interest in oxide glasses. Source: Compilation courtesy J.F. Stebbins.

	Coordinationa	Ionic radiusb (Å)	Field strengthb	Electronegativityc
Anions
O2−	2, 6	1.35, 1.40	–	3.5
F1−	2, 6	1.29, 1.33	–	4.0
Cl1−	6	1.81	–	3.0
Cations Network formers d
Fe3+	4, 6	0.49, 0.55	0.88, 0.82	1.8
Ga3+	4, 6	0.47, 0.62	0.90, 0.77	1.6
Al3+	4, 6	0.39, 0.54	0.98, 0.83	1.5
Te4+	3, 4e	0.52, 0.66	1.13, 0.98	2.1
Ti4+	4, 6	0.42, 0.61	1.26, 1.03	1.5
Ge4+	4, 6	0.39, 0.53	1.31, 1.12	1.8
Si4+	4, 6	0.26, 0.40	1.52, 1.29	1.8
B3+	3, 4	0.01, 0.11	1.60, 1.41	2.0
P5+	4	0.17	2.14	2.1
Modifier to intermediate: alkalis and alkaline earths
Cs1+	8	1.74	0.10	0.7
Rb1+	8	1.61	0.11	0.8
K1+	8	1.51	0.12	0.8
Na1+	6	1.02	0.18	0.9
Li1+	4, 6	0.59, 0.76	0.26, 0.22	1.0
Ba2+	8	1.42	0.26	0.9
Sr2+	8	1.26	0.29	1.0
Ca2+	6, 8	1.00, 1.12	0.36, 0.33	1.0
Mg2+	4, 6	0.57, 0.72	0.53, 0.46	1.2
Be2+	4	0.27	0.75	1.5
Modifier to intermediate: selected others
Sn2+	8e	1.26	0.29	1.8
Pb2+	4, 8e	0.98, 1.29	0.37, 0.28	1.9
Mn2+	6	0.83f	0.42	1.5
Fe2+	6	0.78f	0.44	1.8
Zn2+	4, 6	0.60, 0.74	0.52, 0.45	1.6
Ni2+	4, 6	0.55, 0.69	0.55, 0.48	1.9
La3+	8	1.16	0.47	1.1
Nd3+	8	1.11	0.49	1.1
Er3+	8	1.00	0.54	1.2
Y3+	8	1.02	0.53	1.2
Sc3+	6	0.75	0.67	1.3
Sb3+	4e	0.76	0.67	1.9
Zr4+	8	0.84	0.83	1.4
U4+	6	0.89	0.79	1.7
Mo6+	4, 6	0.41, 0.59	1.92, 1.58	1.8

^a Common coordination numbers; others may occur. Five‐coordinate states are also known for many cations listed with 4 and 6 coordination (e.g. Al, Si, Ti, Ni), which have intermediate radii and field strengths.

^b Cation field strength, valence divided by square of cation–oxygen distance, with the radius of the latter taken as 1.36 Å, the typical value for three‐coordinated O.

^c Pauling electronegativity, from Pauling, L. (1970). General Chemistry. San Francisco: W.H. Freeman.

^d “Network former” description is generally most appropriate for lower coordination numbers.

^e Lone‐pair electronic structure may lead to lower coordination than expected from radius.

^f Radii for high spin electronic state.

^g Effective ionic radius, from Shannon, R.D. (1976). Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Cryst. A32, 751–767.

Table A.2 S.I. units and physical constants.

	Symbol	Value	Unit
Universal constants
Speed of light	c	2.999 792 458 108	m/s
Gravitation constant	G	6.674 08 (31) 10−11	m3/kg/s
Planck constant	h	6.626070 10−34	J/s
		4.135669 2 (12) 10−15	eV s
Masses
Electron	m e	9.109383 56 (11) 10−31	kg
Proton	m p	1.672621898 (21) 10−27	kg
Neutron	m n	1.674927471 (21) 10−27	kg
Physical constants
Avogadro number	N A	6.022140857 (74) 1023
Faraday constant	F	9.648533212331001 84 104	C/mol
Ideal gas constant	R	8.3144598 (48)	J/mol/K
Boltzmann constant	k	1.380649 10−23	J/K
	k/hc	69.503 87 (59)	m−1/K
Stefan–Boltzmann constant	σ	5.670367 (13) 10−8	W/m2/K4
Molar volume of ideal gases (at 273.15 K and 1 atm)	V m	22. 413 962 (13) 10−3	m3
Conversion factors
Electron‐Volt	eV	1.6021766208 (98) 10−19	J
Standard atmosphere	atm	101. 325 103	Pa

Numbers in brackets denote the uncertainties in the final decimal places. Reported values by definition exact when no uncertainties are mentioned.