This table lists the index of refraction of selected crystalline inorganic compounds. When available, values are given as a function of wavelength in the range from the ultraviolet to the far infrared region. For most compounds a value at 589 nm, the wavelength of the principal sodium line, is given. The data have been taken from the references indicated; in many cases, data from a reference have been refitted to generate the index of refraction at the wavelengths used in this table. All values refer to ambient temperature. Entries marked by * are based on extrapolation beyond the range of available experimental data. Column definitions for the table are as follows.
Column heading | Definition |
Mol. form. | Molecular formula of inorganic crystal, list ordered alphabetically |
Cryst. syst. | Crystallographic system of the crystal |
Ray | Notation for isotropic and anisotropic indexes; see below for definitions |
n (200 nm), n (400 nm), etc. | Index of refraction at the wavelength in nm specified within the parentheses |
Ref. | Reference |
Compounds belonging to the cubic crystal system have only a single refractive index value, but other systems are anisotropic, so that the crystal is characterized by two or three unique indexes. Hexagonal, rhombohedral, and tetragonal crystals have two unique indexes that are traditionally labeled no and ne for “ordinary ray” and “extraordinary ray.” Orthorhombic, monoclinic, and triclinic crystals are characterized by three indexes that here are called nx, ny, and nz. The table indicates the crystal system for each entry in order to identify the material uniquely.
Compounds are listed in order of their common formula.
The refractive index and other optical properties for metals, semiconductors, and certain other compounds can be found in the tables “Optical Properties of Selected Elements” and “Optical Properties of Selected Inorganic and Organic Solids” in Section 12 of this CRC Handbook.
Mol. form. | Name | CAS Reg. No. | Cryst. syst. | Ray | n (150 nm) | n (200 nm) | n (300 nm) | n (589 nm) | n (750 nm) | n (1 μm) | n (2 μm) | n (5 μm) | n (10 μm) | n (15 μm) | n (20 μm) | Ref. |
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AgCl | Silver(I) chloride | 7783-90-6 | cub | n | 2.0668 | 2.0401 | 2.0224 | 2.0062 | 1.9975 | 1.9803 | 1.9511 | 1.9069 | 5 | |||
AlPO4 | Aluminum phosphate | 7784-30-7 | rhomb | no | 1.5247 | 1.5203 | 1.5161 | 1.5034 | 6 | |||||||
AlPO4 | Aluminum phosphate | 7784-30-7 | rhomb | ne | 1.5338 | 1.5290 | 1.5245 | 1.5116 | 6 | |||||||
Al2O3 | Aluminum oxide (α) | 1344-28-1 | hex | no | 1.7673 | 4 | ||||||||||
Al2O3 | Aluminum oxide (α) | 1344-28-1 | hex | ne | 1.7598 | 4 | ||||||||||
As2O3a | Arsenic(III) oxide (arsenolite) | 1327-53-3 | cub | n | 1.7537 | 4 | ||||||||||
BaF2 | Barium fluoride | 7787-32-8 | cub | n | 1.677 | 1.557 | 1.5010 | 1.4744 | 1.4712 | 1.4686 | 1.4647 | 1.4511 | 1.4014 | 1.305 | 2 | |
BaO | Barium oxide | 1304-28-5 | cub | n | 1.9841 | 4 | ||||||||||
BaSO4 | Barium sulfate | 7727-43-7 | orth | nx | 1.6362 | 4 | ||||||||||
BaSO4 | Barium sulfate | 7727-43-7 | orth | ny | 1.6374 | 4 | ||||||||||
BaSO4 | Barium sulfate | 7727-43-7 | orth | nz | 1.6480 | 4 | ||||||||||
BaTiO3 | Barium titanate | 12047-27-7 | tetr | no | 2.4405 | 4 | ||||||||||
BaTiO3 | Barium titanate | 12047-27-7 | tetr | ne | 2.3831 | 4 | ||||||||||
BaWO4 | Barium tungstate | 7787-42-0 | tetr | no | 1.8426 | 4 | ||||||||||
BaWO4 | Barium tungstate | 7787-42-0 | tetr | ne | 1.8405 | 4 | ||||||||||
BeO | Beryllium oxide | 1304-56-9 | hex | no | 1.7184 | 4 | ||||||||||
BeO | Beryllium oxide | 1304-56-9 | hex | ne | 1.7342 | 4 | ||||||||||
BeSO4·4H2O | Beryllium sulfate tetrahydrate | 7787-56-6 | tetr | no | 1.4713 | 4 | ||||||||||
BeSO4·4H2O | Beryllium sulfate tetrahydrate | 7787-56-6 | tetr | ne | 1.4328 | 4 |
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