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Vol. 19, No. 12 (1963)

1963-06-20
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CONTENT
ON THE gR FACTOR OF NUCLEI
YANG KUO-SHEN
1963, 93 (12): 771-781. doi: 10.7498/aps.19.771
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A general formula for the gR factor is derived in accordance with the spirit of Skyrme's variational method. Numerial values of gR for nine nuclei in the neighbourhood of Lu175 are obtained using Nilsson's wave functions. The calculated values of gR depend on the discrepancy of the spin-orbit coupling parameter x between the neutron and the proton. They are near to the observed values, smaller than Z/A and greater than those of the cranking model with pair-correlation interaction taken into account.
HOPPING PROCESS AND IMPURITY CONDUCTION IN VALENCE SEMICONDUCTORS
HO YU-PING
1963, 93 (12): 791-806. doi: 10.7498/aps.19.791
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The impurity conduction in the low concentration limit has been analyzed in terms of hopping process. Starting from the Liouville's equation, we have derived an expression for the electrical current and a boltzmann-type equation for diagonal elements of the density matrix in the lowest order of the electron-phonon interaction. If we only take into account the lowest order of W (overlapping integral), the Miller-Abraham's network model has been obtained. By improving the method of averaging we have shown the resistance to be proportional to Kl/3 in low temperature limit, where K is the degree of compensation.Furthermore, using the network model we have analyzed the different parts of the density matrix. The behavior of the diagonal part is much different from that in the ordinary conduction process, and is connected with appearance of the activation energy.By estimating the overlapping integral and energy fluctuation, we conclude that the carriers are mainly not localized in the low compensation case (K-2), if the impurity concentration is larger then a critical value (1014cm-3 in Ge and 1016cm-3 in Si). This does not contradict the experimental facts, if we take into account the Coulomb interaction between electrons.
STRENGTH AND DEFORMATION PECULIARITIES OF BINARY METAL WHISKERS
CHOU N. P., KE T. S.
1963, 93 (12): 807-815. doi: 10.7498/aps.19.807
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The tensile strength of numerous whiskers of Fe, Fe-Cu, Fe-Co, Cu and Cu-Co with diameters ranging from 20 to 300 microns were measured at room temperature and at an elevated temperature. The results show that the strength of the dispersion type of binary metal whiskers such as Fe-Cu and Cu-Co whiskers is higher than that of single-metal whiskers, while the strength of the solution type such as Fe-Co whiskers is not so. On the basis of measurements on stress-strain curves and metallographical observations, it is suggested that the high strength of dispersion type Fe-Cu whiskers may be due to the appearance of a high strength dispersively mixed layer of iron and copper, and the improvement of plasticity may be due to the appearance of an axle whisker of copper having a better plasticity.A discussion was made on the basic processes involved in the thickenning of binary metal whiskers of either type. It is suggested that the procedure adopted in growing dispersion type of binary metal whiskers may serve as a useful guide in preparing high strength composite materials with improved plasticity.
ELECTRONIC PARAMAGNETIC RESONANCE SPECTROGRAPH WITH FREQUENCY AND MAGNETIC FIELD MODULATION
TUONG TAI-CHIAN
1963, 93 (12): 816-823. doi: 10.7498/aps.19.816
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This paper presents a new spectrograph of electronic paramagnetic resonance. Its character is the application of combined frequency and magnetic field modulation. Therefore the structure is simplified. Because the balance adjustment of magic tee is used and a positive voltage is added on the microwave crystal diode, its noise is then reduced near the level of thermal noise. The signal of 5×10-9M. DPPH may be observed on the oscillograph. The ratio of signal to noise is 2:1. The operation frequency is 9690 Mc,/s.
1963, 93 (12): 824-829. doi: 10.7498/aps.19.824
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1963, 93 (12): 830-832. doi: 10.7498/aps.19.830
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