| 释义 |
paramagnetic, a. and n.|pærəmægˈnɛtɪk|
[f. Gr. παρα- in sense ‘alongside, parallel’ + magnetic.]
A. adj.
†1. Having the property of being attracted by the poles of a magnet, and hence, when suspended or placed freely in a magnetic field, of taking a position parallel to the lines of the force; also ferro-magnetic: opp. to diamagnetic. Obs. (superseded by the next sense).
Faraday at first (1846) distinguished diamagnetic from magnetic bodies; afterwards (1850–51) he called the latter paramagnetic, using magnetic to include both.
1850W. Whewell Let. (1876) II. 364 [To Faraday.] Hence it would appear, that the two classes of magnetic bodies are those which place their length parallel or according to the terrestrial magnetic lines, and those which place their length transverse to such lines. Keeping the preposition dia for the latter, the preposition para or ana might be used for the former; perhaps para would be best as the word parallel..would be a technical memory for it. Thus we should have this distribution—Paramagnetic: Iron, Nickel, Cobalt, &c. Diamagnetic: Bismuth, Phosphor, &c. If you like anamagnetic better than paramagnetic, as meaning magnetic according to our standard, terrestrial magnetism, I see no objection. 1851Faraday Exp. Res. in Electr. No. 2790 in Phil. Trans. 26 As the magnetism of iron, nickel, and cobalt, when in the magnetic field is like that of the earth as a whole, so that when rendered active they place themselves parallel to its axis or lines of magnetic force, I have supposed that they and their similars (including oxygen now) might be called paramagnetic bodies, giving the following division—Magnetic: (1) Paramagnetic, (2) Diamagnetic. Ibid. No. 2834. 39 Masses of paramagnetic matter. 1855Maury Phys. Geog. Sea vi. (1858) §376 Faraday has shown that, as the temperature of oxygen is raised, its paramagnetic force diminishes, being resumed as the temperature falls again. 1880[see ferromagnetic a. 1]. 1895Story-Maskelyne Crystallogr. i §13 Unmagnetised bodies if brought near a magnetic pole are either attracted or repelled by it, and are said to be magnetised by induction; being described in the former case as paramagnetic and as diamagnetic in the latter case.
2. a. Of a body or substance: very weakly attracted by the poles of a magnet but not retaining any permanent magnetism; having a susceptibility that is positive but small, so that the relative permeability is only slightly greater than one and hysteresis does not occur. b. Characteristic of or pertaining to paramagnetism. Cf. ferromagnetic a. 2 and the note there.
1896, etc. [see ferromagnetic a. 2.]. 1902Encycl. Brit. XXX. 430/2 The magnetic susceptibility of a vacuum..is 0, that of a diamagnetic substance..has a negative value, while the susceptibility of paramagnetic and ferromagnetic substances..is positive. 1903Proc. R. Soc. LXXI. 239 The law of Curie, that the susceptibility of weak paramagnetic substances is inversely proportional to the absolute temperature. 1931S. R. Williams Mag. Phenomena v. 159 Oxygen, palladium, air, glass, porcelain, and FeSO4 were some of the paramagnetic bodies studied by Curie. 1958N. Cusack Electr. & Magn. Prop. Solids xii. 269 At a critical temperature, called the Curie point.., ferromagnetic matter undergoes a phase transition and becomes paramagnetic. 1966C. R. Tottle Sci. Engin. Materials vi. 133 Curie..deduced the law for paramagnetic susceptibility.
B. n. A paramagnetic body or substance.
1855Phil. Mag. IX. 293 The assertions I have made regarding mutual influence..are confirmed amply by experiment for paramagnetics. 1911Encycl. Brit. XVII. 324/1 Between the ferromagnetics and the paramagnetics there is an enormous gap. 1914,1962[see ferromagnetic n.]. 1966C. R. Tottle Sci. Engin. Materials vi. 134 The group of elements iron, cobalt, nickel demonstrates this. Below a certain critical temperature these elements remain permanently magnetized after removal of the external field... Above it, the materials behave as normal paramagnetics.
Hence paramagˈnetically adv.
1883Encycl. Brit. XV. 248/2 By virtue of differential action, a body may behave paramagnetically or diamagnetically according as it is placed in a less or in a more permeable medium than itself. 1974Nature 31 May 426/1 The reduction at 25° C of the cytochrome c3 from Desulfovibrio vulgaris..has been studied by following the paramagnetically shifted NMR resonances which lie to very low field. |