430 TABLE 450.— DIELECTRIC CONSTANT OF CRYSTALS* 



cgs system, K v » C uum = 1 



The dielectric constants, t K, given here have usually been determined at low field 

 strength (order of 1 volt/cm). Unless specifically noted, the frequency is between 60 

 cycles/sec and 5 megacycles/sec. Homogeneous crystals show little dispersion in this 

 frequency range unless they are strongly piezoelectric or have very high dielectric constant. 

 For some strongly piezoelectric crystals, the notation "free" appears in the frequency 

 column. Dielectric constants so noted hold for the mechanically unconstrained condition 

 which is usually fulfilled for frequencies below the principal mechanical resonances of the 

 test body. The dielectric constants for the "clamped" crystal are smaller than for the 

 "free" crystal. The difference does not exceed 10 percent except for K a of Rochelle salt 

 (see fig. 16) and K\\ of barium titanate. 



K tt , Kb, and K„ for orthorhombic crystals refer to electric field parallel to the crystallo- 

 graphic a, b, and c axes. 



For monoclinic crystals, Kb refers to electric field parallel to the b axis which is the 

 symmetry axis ; K c to field parallel to the c axis accepted by crystallographic convention ; 

 and Km to an electric field perpendicular to the b and c axes. 



* Tables 444, 450, and 451 prepared by Hans Jaffe, Brush Development Co., Cleveland, Ohio, 

 data refer to room temperature unless otherwise noted. 



Cubic crystals 



t All 



Compo- 



Name sition 



Silver chloride . . . AgCl 



Silver bromide . . . AgBr 



Lithium fluoride . . LiF 



Sodium chloride . . NaQ 



Potassium chloride KC1 



Barium oxide BaO 



Author- Compo- 



K ity 14S Name sition K 



12.3 g Sphalerite ZnS 8.8 



13.1 g Sodium chlorate . . NaClOs 5.7 



9.00 f Sodium bromate . . NaBrOs 5.7 



5.90 f Magnesium oxide . MgO 9.65 



4.68 g Potassium bromide KBr 4.90 



34. o Thallium chloride. T1C1 31.1 



Author- 

 ity 



e 

 h 

 h 

 f 

 f 

 g 



Uniaxial crystals 



Name Composition K _]_ K \\ 



Quartz Si0 2 4.5 4.6 



Calcite CaCO, 8.78 8.29 



Sapphire Al 2 3 t 8.6 10.5 



Rutile Ti0 2 t 86 170 



Barium titanate BaTiOs 4400 200 



Tourmaline 8.2 7.5 



Magnesite MgC0 3 6.91 8.1 



Dihydrogen phosphates and arsenates : 



"ADP" NH 4 H 2 P0 4 56 15.4 



"KDP" KH 2 P0 4 46 22 



"ADA" NH 4 H 2 As0 4 75 14 



"KDA" KH 2 AsQ 4 52 22 



Frequency 



10 2 — 10 7 



10 6 -10° 

 ?-10 7 



free 

 free 

 free 

 free 



Authority 

 b 



g 

 f 

 f 

 i 



h 

 g 



d 

 h 

 d 

 d 



Orthorhombic crystals 



Name Composition K» Kb Kc 



Sulfur S 3.75 3.95 4.45 



Celestite SrS0 4 7.7 18.5 8.3 



Barite BaS0 4 7.65 12.2 7.7 



Anglesite PbS0 4 27.5 54.6 27.3 



Epsomite MgS0 4 -7H 2 6.5 7.9 6.9 



Ammonium oxalate (NH 4 ) 2 C 2 4 -H 2 8.2 5.5 6.0 



Potassium pentaborate . KB 5 (V4H 2 4.6 5.5 4 5 



Iodic acid HI0 3 7.5 12.4 8.1 



149 For authorities, see references, p. 431. 

 t Synthetic, Linde Air Products Company. 



(continued) 



Author- 

 ity 



f 

 g 

 g 



Frequency 



io'xio 8 



4X10 8 

 4X10 8 



sxio^-io'g 



k 

 free k 



free d 



free h 



SMITHSONIAN PHYSICAL TABLES 



