Papers by Keyword: Electron Concentration

Abstract: A possibility of using the electron concentration calculation method to evaluate Ac_m and Ac₃ temperatures in the Ti-Cr system alloys with different hydrogen content (0.15-0.93 wt %) is considered. It is found that the proposed method gives results similar to the experimental data only in the case of low hydrogen concentrations since it does not take into account the degree of hydrogen ion screening by electrons.

Abstract: The present paper covers in a comprehensive manner the formation of the Cu-based Cu-Zr-Al bulk metallic glasses (BMGs). Composition optimization for BMG formation is realized by using an “e/a-variant criterion”. This criterion is incorporated into the ternary phase diagram by a straight composition line, which is defined by linking a specific binary composition to the third element. There e/a-variant composition lines are constructed: (Cu9Zr4)1-xAl, (Cu61.8Zr38.2)1-xAlx and (Cu56Zr44)1-xAlx, where Cu9Zr4, Cu61.8Zr38.2 and Cu56Zr44 are specific cluster compositions in the Cu-rich Cu-Zr binary system. No Cu-based BMGs are obtained in the composition line (Cu9Zr4)1-xAlx using our suction casting techniques, while BMGs are obtained within an e/a span from 1.24 to 1.3 and from 1.28 to 1.36 respectively along the other two lines (Cu61.8Zr38.2)1-xAlx and (Cu56Zr44)1-xAlx. Thermal analysis results indicate that the BMGs on every composition line manifest increased thermal stability and glass forming ability (GFA) with increasing e/a ratios. The maximum appears in Cu58.1Zr35.9Al6 with the e/a value of 1.3, which belongs to the (Cu61.8Zr38.2)1-xAlx series. The characteristic thermal parameters of this BMG are Tg = 760K, Tg/Tm = 0.659 and Tg/Tl = 0.648, which are all superior to those reported for the known Cu55Zr40Al5 BMG.

Abstract: In order to understand carrier statistics in phosphorus-doped n-type diamond, electron statistics involving compensation and deep-dopant effect are theoretically analyzed. For n-diamond with a compensation ratio (c) larger than 1x10-4, the electron concentration (n) at room temperature (RT) is insensitive to the donor concentration (ND) and reduced with increasing the c value. On the other hand, for diamond with a c value smaller than 1x10-4, the n value at RT increases with increasing the ND value and is insensitive to the c value. Similarly, the length of Debye tailing (ln) at RT is reduced with increasing the c value for n-diamond with c>1x10-4 and is insensitive to the c value for n-diamond with c<1x10-4. However, it is found that an increase of temperature is effective to increase the n value and to reduce the ln value. The n value as large as 1015 cm-3 and the ln value as small as 100 nm are expected to be achieved at an elevated temperature of 473 K.