Papers by Keyword: Dopant

Abstract: Recently, pure PZT have been used as a piezofan in electronic application. Properties that piezoelectric fan should have are high mechanical piezoelectric coupling factor, high dielectric constant, easily polarized and high piezoelectric charge constant. Soft PZT is a suitable candidate to fulfill this requirement. The samples will be prepared via high planetary mill; due to this process can skip calcinations process, which can reduce a lot of cost. This process also can avoid PbO loss during sintering process. The microstructure and electrical properties of PZT ceramic were found to be more sensitive to the sintering condition. Preliminary works have been done in order to find a suitable sintering duration in order to produce a good PZT formation. SEM analysis indicated that shorter sintering time promotes fine structure and densification. This have been proves where relative density of the obtained sintered PZT ceramics was measured to be approximately 99 % of the theoretical density.

Abstract: The oxygen permeability of polycrystalline α-alumina wafers, which served as model alumina layers, under an oxygen potential gradient ΔP_O2 was evaluated at a temperature of 1873 K. When mutual grain boundary (GB) diffusion of oxygen and aluminum occurred in wafers subjected to a steep ΔP_O2, the oxygen and aluminum fluxes at the inflow side of the wafer were significantly smaller than those at the outflow side. It was noteworthy that Lu and Hf segregation at the GBs selectively reduced the mobility of oxygen and aluminum, respectively. It was found that a wafer with a bilayer structure, in which a Lu-doped layer was exposed to a low partial oxygen pressure (P_O2) and a Hf-doped layer was exposed to a high P_O2, exhibited excellent oxygen shielding properties at high temperatures.

Abstract: Zinc sulfide (ZnS) has been reported to act as a photocatalyts to reduce water to hydrogen. However, ZnS could not work under visible light irradiation due to its large band gap energy. In order to improve the performance of ZnS, Ga and Sn were doped to ZnS. The series of Ga (0.1),Sn (x)-ZnS with various amounts of Sn (x) was prepared by hydrothermal method. XRD patterns suggested that the addition of Ga might reduce the crystallinity of ZnS, suggesting that Ga might inhibit the crystal growth or agglomeration of ZnS. On the other hand addition of Sn did not much affect the structure of the Ga (0.1)-ZnS. The DR UU-visible spectra confirmed the red shift of the absorption edge with the addition of Ga due to the reduced band gap energy, while the addition of Sn did not much shift the absorption edge of the Ga (0.1)-ZnS to longer wavelength. FESEM images showed that all the prepared samples have sphere-shaped particles and no remarkable change was observed with the addition of Ga or Sn. The photocatalytic hydrogen production from water was carried out at room temperature in the presence of sacrificial agent under visible light irradiation. While ZnS did not show activity under visible light, all the prepared Ga (0.1)-ZnS and Ga (0.1),Sn (x)-ZnS samples exhibited photocatalytic activity for hydrogen production. The highest hydrogen production was achieved on Ga (0.1),Sn (0.01)-ZnS, which activity was ca. three times higher than that of the single doped Ga (0.1)-ZnS. This study clearly showed that Sn acted as a good co-dopant to increase the photocatalytic activity of Ga (0.1)-ZnS for hydrogen production from water under visible light irradiation.

Abstract: The lowest energetic configurations of metal impurities in 4^th row (Sc - Zn), 5^th row (Y - Cd) and 6^th row (Hf - Hg) elements in Ge crystals were determined with density functional theory calculations. It was found that the substitutional site is the lowest energetic configuration for most of the calculated metals in Ge. The most stable configurations of dopant (Ga, Sb) - metal complexes in Ge crystals were also investigated. Following results were obtained. (1) For Ga dopant, 1st neighbor T-site is the most stable for metals in group 3 to 7 elements while substitutional site next to Ga atom is the most stable for metals in group 8 to 12 elements. (2) For Sb dopant, substitutional site next to Sb atom is the most stable for all calculated metals. Binding energies of the interstitial metal M_i with the substitutional dopant D_s were obtained by the calculated total energies. The calculated results for Ge were compared with those for Si.

Abstract: The reaction parameters about oxidative chemical polymerization of aniline in hydrochloric acid were seriously studied. The optimization parameters of the preparation of polyaniline were obtained: the concentration of aniline is 4％（mass percentage），the molar rate of oxidant((NH4)2S2O8):aniline is 1.2:1~1.3:1, the concentration of dopant is 1mol/L and the influence of solvent. FTIR was employed to character the structure of polyaniline.

Abstract: The effects of Na and Mg doped Li site for Li_1-xM_xFePO₄ have been studied using first-principles within GGA+U. Elastic band method has been used to calculate the activation energy for Li diffusion. The calculated results mean that, the band gaps of the Na and Mg doped Li_1-xM_xFePO₄ are both narrow than that of the un-doped. Especially Mg dopant gives rise to much narrow gap, which is attributed to the appearance of impurity level in the forbidden band of un-doped LiFePO4. The calculated activation energies for LiFePO₄, Li_0.875Na_{0.125Subscript text}FePO₄, and Li_0.875Mg_0.125FePO₄ are 0.33eV, 0.31 eV, and 0.15 eV, respectively. From the calculated results of band gap and activation energy, we can find that Mg dopant will benefit for the hopping of electrons and the improvement of the electronic conductivity for LiFePO₄.

Abstract: The present article prepared tungsten wire using doped Co, sintering and stretching. By metallographic analysis and mechanical performance test, it discussed the effect of Co on the performance of the seismic tungsten filament. This article studied the effect of additive Cobalt on the ductility, recrystallization temperature and performance of organization on the aseismatic tungsten filament preparation process. It shows that, Co can purify tungsten matrix. Adding Cobalt in doped tungsten can improve the tungsten second recrystallization temperature, and reduce the temperature of plastic-brittle transition. It had a large L/W and small cold-brittleness after annealing, and its seismic performance at high temperature was effectively improved.

Abstract: Inverse opal films (IOFs) of SnO₂ doped with Pd were prepared by the self-assembly technique using polystyrene microsphere (PS sphere) as template in combination with a sol-gel method. The photocatalysis properties of SnO₂ IOFs were estimated through measuring the rate of the degradation of methylene blue (MB). The result shows that SnO₂ IOFs have good photocatalytic activity, the solution of MB was degradated over 60% in 4 hours when it was dipped in SnO₂ IOFs and exposed in the UV light. The addition of Pd in SnO₂ IOFs improved the photocatalytic activity of the films and the degradation of MB can exceed 80% with the same condition. This sort of SnO₂ IOFs doped with Pd indicated a potential application in photocatalysis field.

Abstract: An all-wet process based on a novel chemistry has been developed to enable the removal of high-dose implanted photoresist in the presence of exposed metal layers and other materials typical of advanced gate stacks.

Abstract: We report in this work some process optimization effort in performing poly silicon removal for replacement gate process integration. Successful wet poly silicon removal after dummy gate patterning is not only conditioned by suitable process conditions during wet removal but is also impacted by process steps prior to gate removal A thorough evaluation of the impact on poly removal from dopants or contaminants introduced in the poly silicon by previous processing is done, resulting in an optimized integration flow with successful poly removal. This work also shows that use of diluted TMAH chemistry instead of diluted ammonia in performing poly silicon removal provides better ability in removing poly silicon especially in narrow gate structures.