432 



TABLE 451.— PIEZOELECTRICITY 



In this table are listed piezoelectric strain coefficients * d nm which are ratios of piezoelec- 

 tric polarization components to components of applied stress at constant electric field 

 (direct piezoelectric effect) and also ratios between piezoelectric strain components to ap- 

 plied electric field components at constant mechanical stress (converse effect). The sub- 

 scripts n = 1 to 3 indicate electric field components, m = 1 to 6 mechanical stress or strain 

 components. These components are referred to orthogonal coordinate axes. For correla- 

 tion of these to crystallographic axes, we follow Standards on Piezoelectric Crystals. 1 " 



In the monoclinic system, indices 2 and 5 refer to the symmetry (b) axis, in distinction 

 from the older convention b relating indices 3 and 6 to the symmetry axis. Crystal classes 

 are designated by international (Hermann-Mauguin) symbols. A dot in place of a coeffi- 

 cient indicates that it is equal by symmetry from another listed coefficient ; a blank space 

 indicates that the coefficient is zero by symmetry. If the sign of a coefficient is not given 

 it is unknown, not necessarily positive. 



Unit for d nm = 10~ e statcoulomb/dyne = -r- X 10~ u coulomb/newton 

 = 10" 8 cm/statvolt = j X 10" 12 meter/volt 



* The coefficient d u of Rochelle salt is extremely dependent on temperature and on amplitude. The 

 ratio of d lt to dielectric constant K (for the latter see figure 16) is, however, nearly constant; Aird lt /K r= 

 g u = 6.4X10" 7 statvolt cm/dyne. 



m Letters refer to references, p. 431. 



Cubic and tetragonal crystals 



Name Composition Class du 



Sphalerite ZnS 43m 9.7 



Sodium chlorate NaClOa 23 5.2 



Sodium bromate NaBrOa 23 7.3 



"ADP" NH 4 H 2 PO 42m —1.5 



"KDP" K H 2 P0 4 42m + 1.3 



"ADA" NH 4 H 2 AsC>4 4_2m +41 



"KDA" KH 2 As0 4 42m +23.5 



d* 



+48.0 

 +21 

 +31 

 +22 



Authority 149 



b 



1 

 1 



d 

 e 

 d 

 d 



Name Class 



Quartz 32 



Tourmaline 3m 



Trigonal crystals 



da 



+6.9 



d u 



-2.0 



+ 11.0 



d 22 dsi dz 3 Authority 



b 

 .94 +.96 +5.4 b 



Orthorhombic crystals 



Substance Class 



Epsomite 222 



Iodic acid 222 



Rochelle salt (30° C) ... 222 



NaNH« tartrate 222 



LiK tartrate 222 



LiNH« tartrate 222 



(NH 4 ) 2 oxalate 222 



K pentaborate mm 



du 

 -6.2 

 57 

 + 1500* 

 +56 

 9.6 

 13.2 

 50 



9.5 



1.7 



rf 2 J 



-8.2 

 46 

 -160 

 -150 

 33.6 

 19.6 

 11 



d n 



-5.4 



^30 



-11.5 

 70 



+35 



+28 

 22.8 

 14.8 

 25 



Authority 

 1 



h 

 b 

 b 

 h 

 h 

 e 



dm Authority 



+5.6 d 



Monoclinic crystals (Class 2) 



Substance d u rf ]6 d a d^ d 2 \ d^ du d- 



Lithium sulfate +14.0 —12.5 +11.6 —45.0 —5.5 +16.5 —26.4 +10.0 



Tartaric acid +24.0 +15.8 —2.3 -6.5 —6.3 +1.1—32.4+35.0 



K 2 tartrate (DKT) .... -25 +6.5 -2.2 +8.5 -10.4 —22.5 +29.4 —66.0 



(NH,) 3 tartrate +9.3 —8.5+17.6—26.2 +1.8 —5.9—14.0 +5.6 



EDT -31.1 —36.5 +30.6 +6.6 -33.8 —54.3 —51 —56.9 



(Ethylene diamine tartrate) 



Cane sugar -3.7 —72 +4.4—10 +2.2 —2.6 —1.3 +1.3 



(continued) 



Authority 



h 

 h 

 h 

 1 

 a 



SMITHSONIAN PHYSICAL TABLES 



