11^ 



Tables 459-462. 



MAGNETISM AND TEMPERATURE. 

 TABLE 459. — Magnetism and Temperature, Critical Temperature. 



The magnetic moment of a magnet diminishes with increasing temperature. DiSerent specimens vary widely. 

 In the formula M (/Afo = (i — at) the value of a may range from .0003 to .001 (see Tables 457-458). The effect on the 

 permeability with weak fields may at first be an increase. There is a critical temperature (Curie point) above which 

 the permeability is very small (paramagnetic?). Diamagnetic susceptibility does not change with the temperature. 

 ' — - - ''*- ■ ' * — This and the succeedmg two tables are taken 



Paramagnetic susceptibility decreases with increase in temperature, 

 from Dushman, "Theories of Magnetism," General Electric Review, 



1916. 



Substance. 



Iron, a form 



" & form 



" Y form 



Magnetite (FeaOi) 



Cobalt-ferr'ite (FeaCo) '. '. '. 



Critical 

 temperature, 

 Curie point. 



756° 

 920 

 1280 

 536 

 589 

 5SS 

 520 



Refer- 

 ence. 



Substance. 



MnBi 



MnSb 



MnAs 



MnP 



Heusler alloy 

 Nickel 



Cobalt 



Critical 



temperature, 

 Curie point. 



360 to 380° 

 310 " 320 



50 

 ' 25 

 310 

 340 

 376 

 I07S 



Refer- 

 ence. 



References: (i) P. Curie; (2) see Williams, Electron Theory of Magnetism, quoted from Weiss; (3) du Bois, 

 Tr. Far. Soc. 8, 211, 1912; (4) Hilpert, Tr. Far. Soc. 8, 207, 1912; (s) Gumaer; (6) Stiller, Phys. Rev. 33, 268, 1911. 



TABLE 460. — Temperature Variation for Paramagnetic Substances. 



The relation deduced by Curie that x = C/T, where C is a constant and T the absolute temperature, holds for some 



f)aramagnetic substances over the ranges given in the following table. Many paramagnetic substances do not obey the 

 aw (Honda and Owen, Ann. d. Phys. 32, 1027, 1910; 37, 657, 1912). See the foUowmg table. 



Substance. 



Oxygen . . . 



Air 



Palladium. 

 Magnetite 

 Cast iron. 



C X io« 



33,700 



7,830 



1,520 



28,000 



38,500 



Range ° C 



20° to 450° C 



20 to 1370 

 850 " 1360 

 850 " 1267 



Refer- 

 ence. 



Substance. 



Gadolinium sulphate. 

 Ferrous salphate. . . . 



Ferric sulpliate 



Manganese chloride. 



C X 10' 



21,000 

 11,000 

 17,000 

 30,000 



Range ° C 



-259 to 17 



-259 " 17 



-208 "17 



-258 " 17 



Refer- 

 ence. 



References: (i) P. Curie, London Electrician, 66, 500, 1912; see also Du Bois, Rap. du Cong. 2, 460, 1900; (2) Per- 

 rier, Onnes, Tables annuelles, 3, 288, 1914; (3) Oosterhuis, Onnes, I.e. 2, 389, 1913. 



TABLE 461. — Temperature Effect on Susceptibility of Diamagnetic Elements. 



No effect: 



B Cryst. 400 to 1200° P white 



C Diamond, +170 to 200° S Cryst.; ppt. 



C "Sugar" carboa Zn —170 to 300° 



Si Cryst. As — 



Increase with rise in Temperature: 



Be — 



B Cryst. -(-170 to 400° 



Decrease with rise in Temperature: 



C Amorphous Gd —179 to 30° In —170 to 150° 



C Ceylon graphite Ge —170 to 900° Sb -f 50 to -^-631° 



Cu — Zr 500 to 1200" Te — 



Zn -I-300 to 700° Cd 300 to 700° I -I-114 to -f 200° 



Se — 



Br —170 to 18° 



Zr Cryst. —170 to 500° 



Cd —170 to 300° 



C Diamond, 200 to 1200° 

 Ag - 



Sb —170 to so" 

 Cs and Au 

 Hg -39 to -h-sso" 

 Pb 327 to 600° 



I —170 to 114* 

 Hg —170 to —30* 



Tl — 



Pb -170 10327" 

 Bi —170 to 268° 



TABLE 462. — Temperature Effects on Susceptibility of Paramagnetic Elements. 

 No effect: 



Li — K —170 to 150° Cr —170 to 500° W — 



Na —170 to 97° Ca —170 to 18° Mn —170 to 250° Os — 



Al 657 to 1100° V —170 to 500° Rb — 



Increase with rise in Temperature: 



Ti —40 to 1100° 

 V 500 to 1 100" 



Cr SCO to 1100° 

 Mo —170 to 1200° 



Ru +SSO to 1200° 

 Rh — 



Decrease with rise in Temperature: 



(0) — Ti -180 to -40' 



As —170 to 657° Mn 250 to lois" 



Mg - (Fe) - 



Tables 461 and 46J are due to Honda and Owen; for reference, see preceding table. 



Smithsonian Tables. 



Ni 3.=;o to Soo" 

 Co above 1150" 

 Cb —170 to 400° 



Ba —1:0 to iS 

 Ir and Th 



Pd and Ta 



Pt and U 



Rare earth metals 



