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Similar to Magnetic materials
Magnetic materials
- 1.
- 2. 1. The orbitalmotion of electrons -orbital magnetic moment(magnitude is small)
- 3. Spin motion ofthe electrons -spin magnetic moment.
- 4. • To thepresence or absence of the permanent magnetic dipoles.
- 5. • The orbitalmotion of electron revolving about a nucleus is equivalent to a tiny current loop. This produces a magnetic field perpendicular to the plane of the orbit
- 6. • Energy states– it will form a pair with opposite spins. • Resultant spin magnetic moment is zero. • Don’t have permanent magnetic moments ex. Diamagnetic materials (gold, germanium, silicon) Energy
- 7. • Those materialshaving unpaired electrons. • Spin magnetic moment of these unpaired electrons interact adjacent atoms. • It has enormous permanent spin magnetic moment. Classification of magnetic materials Not having permanent magnet moment Dia magnetic material Having permanent magnetic moment 1.Para magnetic 2.Ferromagnetic 3.Ferrri magnetic materials
- 8. diamagnetism • The atomsin Diamagnetic material do not possess permanent magnetic moment. • It is placed in M.F , the electrons tend to counteract the external M.F. The atoms acquire an induced magnetic moment. H =0 Atoms possess zero magnetic moment
- 9. • The materialmagnetized. • The direction of the induced dipole moment is opposite (due to applied magnetic field ) • The material gets very weakly repelled in the M.F - diamagnetism Ho is applied , atoms acquire an induced magnetic moment
- 10. • Strength ofthe induced magnetic moment is proportional to the Ho • Hence magnetisation of the material varies directly with strength of the Ho • When Ho is removed the magnetization is vanished.
- 11. Langevin’s theroy ofdamagnetism • Materials exhibit diamagnetism due to the orbital motion of an electron and produce a – ve susceptibility. χm =μind/H = -e2 r0 2 µoN/6m μind-inducedmagneticmoment e=chargeofanalectron r0 radiusofatom µo permeability in free space. N – number of atoms per unit volume, m- mass of the electron
- 12. conclusions is independent oftemperature is negative is proportional to the N
- 13. properties • They repelthe magnetic lines of force • I is –ve and independent of temperature and Ho ( applied M.F) • Ppermeability is less than 1 • There is no permanent dipole moment -weak magnets. • When temperature is less than critical temperature diamagnetic become normal material.
- 14. Absence of externalmagnetic field those material (atom or molecule) possesses permanent magnetic moment 1. Magnetic moments are randomly oriented 2. Net magnetic moment zero and magnetization is zero. Paramagnetic materials
- 15. Field is applied Magneticdipoles tend to align themselves in the direction of the magnetic field. The materials becomes magnetized.
- 16. • High temperatureis leading to decrease in magnetization. susceptibility is inversely temperature. • susceptibility = C/T (Curie law of paramagnetism ) • C is a constant – curie constant.
- 17. Langevin’s theory ofparamagnetism • χ, = µ2 m µoN/ 3KT N- Number of molecules per unit volume µo -permeabillity in free space µ2 m magnetic dipole moment of atom k-Boltzmann’s constant T-temperasure χ, =C/T where C=µ2 m µoN/ 3K (curie’s constant)
- 18. properties 1. The magneticlines of force pass through the material. 2. Magnetic susceptibility is +ve . χ, =C/T –θ (Curie-weiss law) here, C-curie constnat,T-absolute temperature, θ- Curie temperature. 3. Permeability is greater than one. 4. They possess permanent dipole moment 5. When the temperature is less than curie temperature, paramagnetic materials becomes diamagnetic material. ( CuSO4 , platinum , nickel sulphate ,etc.) 6. Spin alignment is shown
- 19. Ferromagnetism • These materialsshow the spontaneous magnetization. • Absence of external field, the magnetic moments align themselves parallel to each other and give rise to magnetic field. • When field is applied , magnetic moments reorient itself along the direction of the magnetic field and they become very strong magnets.
- 20. Properties • Science somemagnetisation is already existing in these materials, all the magnetic lines fore passes through it. (strongly attracted ) • They have permanent dipole moment. • They act as strong magnets. • the exhibit magnetisation even in the absence of external field. This property is called spontaneous magnetisation
- 21. • Susceptibility is+ve and high. • When the temperature is greater than curie temperature, ferromagnetic material becomes paramagnetic materials. • Permeability is very much greater than 1. • Dipole alignment is as shown. • They exhibit hysteresis curve. • χ, =C/T –θ (for T> θ , para T< θ, ferro Ex. Ni, co, Fe, etc.