共查询到20条相似文献,搜索用时 729 毫秒
1.
The kinetics of the transformation from the disordered f.c.c. to the ordered b.c.t. were studied in Au4V by measuring electrical resistivity, magnetic susceptibility and microhardness. The resistivity maximum is related to the SRO, whereas the correlation of the above mentioned properties with the integrated X-ray intensity of the superlattice lines shows that the magnetic changes occur simultaneously with the nucleation and growth of the ordered phase. 相似文献
2.
A continuous wave (CW), extra-cavity singly resonant optical parametric oscillator (SRO) has been demonstrated. The SRO was
based on 5% Magnesium-Oxide doped periodically-poled Lithium Nio-bate (MgO:PPLN) pumped by a Yb fiber laser centered at 1064.7
nm. The SRO was able to generate light with idler wavelengths ranging from 2.9 to 4.1 μm. For a pump power of 15 W, the idler
output power varied from 7.54 W at 3.03 μm to 1.04 W at 4.05 μm. The oscillation thresholds were 2.0 W at idler wavelength
3.03 μm and 7.0 W at 4.05 μm. 相似文献
3.
GuoZhen Liu Meng He KuiJuan Jin GuoZhen Yang HuiBin Lü Kun Zhao ShiJian Zheng XiuLiang Ma 《中国科学G辑(英文版)》2008,51(7):745-749
High-quality SrRuO3 (SRO) thin films and SrTiO3/SRO bilayer were grown epitaxially on SrTiO3 (STO)(001) substrates by laser molecular beam epitaxy. The results of in situ observation of reflection high-energy electron diffraction and ex situ X-ray diffraction ϑ-2ϑ scan indicate that the SRO thin films have good crystallinity. The measurements of atomic force microscopy and scan tunneling
microscopy reveal that the surface of the SRO thin film is atomically smooth. The resistivity of the SRO thin film is 300
μΘ·cm at room temperature. Furthermore, the transmission electron microscopy study shows that the interfaces of STO/SRO and
SRO/STO are very clear and no interfacial reaction layer was observed. The experimental results show that the SRO thin film
is an excellent electrode material for devices based on perovskite oxide materials.
Supported by the National Natural Science Foundation of China (Grant No. 10334070) 相似文献
4.
S. P. Belyaev A. E. Volkov R. F. Konopleva I. V. Nazarkin S. A. Pul’nev V. L. Solovei V. A. Chekanov 《Physics of the Solid State》2003,45(2):339-344
The influence of neutron irradiation on the temperature kinetics of thermoelastic martensitic transformation in a Cu-Al(13.4%)-Ni(5%) alloy single crystal is investigated by measuring the electrical resistivity directly under irradiation of the sample in a nuclear reactor channel. It is revealed that, after irradiation of the crystal in a martensitic or two-phase state, the temperature of the phase transition upon heating becomes 25–30 K higher than that prior to irradiation. This shift in the transition temperature is observed only upon the first heating, and the kinetics of martensitic transformation is restored in subsequent thermocycles. The shift in the transformation temperatures after irradiation increases with an increase in the fluence. The experimental results are explained by a disturbance of coherence at the interfaces in the irradiated crystals. 相似文献
5.
We describe a compact all-solid-state continuous-wave singly resonant optical parametric oscillator (SRO) with a minimal pump-power requirement. The SRO is based on periodically poled LiNbO(3) as the nonlinear material and is pumped by a 1-W diode-pumped Nd:YVO(4) minilaser at 1.064 microm . By exploiting the intracavity pumping technique in a 50-mm crystal, we have achieved SRO operation threshold at a diode pump power of only 310 mW.At 1 W of input diode power, the SRO delivers 70 mW of output power in the nonresonant idler at 3.66 microm , at a photon conversion efficiency of 55%. Multiparameter tuning of the SRO yields a signal wavelength range from 1.45 to 1.60 microm and an idler wavelength range from 3.16 to 4.02 microm in the mid infrared. The device is characterized by robust turnkey operation and long-term amplitude-stable performance. 相似文献
6.
如何有效预测高熵合金的稳态结构,是开展研究其物理及化学等性能的基础.以FeCuCrMnMo合金为例,在有限晶胞尺寸内,采用蒙特卡洛结合密度泛函理论杂化计算方法(Monte Carlo/density functional theory,MC/DFT)预测高熵合金的平衡态结构.与准随机近似方法(special quasirandom structures,SQS)不同,该方法不再追求高熵合金结构的理想随机状态,而是充分考虑合金中原子尺寸、混合焓、原子间相互作用等物理因素.通过第一性原理计算体系能量来实现,使得蒙特卡洛(Monte Carlo,MC)方法保证结构在原子交换过程中体系能量逐渐收敛于平衡态.最终预测得到的平衡态结构出现Cu原子的短程有序现象(short range order,SRO)与实验上合金中的Cu偏析现象相一致.相较于由SQS方法获得的随机状态,该SRO结构在能量上更加稳定.同时本文对稳态结构通过序参数及径向分布函数进行表征,并对SRO现象的出现进行物理解释,进一步揭示了SRO的出现对高熵合金结构性质的影响. 相似文献
7.
8.
Ultra-thin SrRuO3 (SRO) films have been grown on ferroelectric and piezoelectric PMN-PT substrates. The structural properties of these films have been characterized by atomic force microscopy, x-ray diffraction and cross-sectional transmission electron microscopy. The nature of electric transport was analyzed in detail and the conduction mechanism of SRO films evolves through three regimes: from a three-dimensional (3D) metallic through a weakly localized to a strongly localized behavior as film thickness is reduced. The bias electric field modulations of transport properties and magnetic properties were explored for these films. We also demonstrate that ferroelectric (FE) domain switching induces a reversible tuning of the magnetic and electric properties in SRO/PMN-PT heterostructure. The FE domain switching in the substrate contributes to an in-plane strain that changes the spin exchange coupling in the SRO layer, and therefore results in a reversible resistance difference of up to 16%. This modulation effect on the electric properties by an electric field demonstrates great potential for the applications of all-oxides spintronics devices. 相似文献
9.
We have measured the resistivity of Mg and Mn up to 0.5 at. % impurity concentration between 0° and 100°C. The results for the resistivity for both systems can be analysed within one generalized model in which spinfluctuations as well as changes in the electron-phonon interaction are considered. For Mn a calculation of the impurity contribution to d?/dT is attempted. For Mg there are indications that the superconducting Tc will increase with Mg concentration. 相似文献
10.
Magnetic diffuse peaks observed around the type positions in reciprocal space have been studied in AgMn spin glass alloys by using neutron diffraction techniques. The position parameter δ of AgMn alloys coincides with that for CuMn alloys with the same Mn content even though the former has a larger lattice spacing than the latter by about 10%. The results suggest that the origin of the satellite diffuse peaks comes from a Fermi surface effect such as the RKKY interaction. 相似文献
11.
Compact,continuous-wave,singly resonant optical parametric oscillator based on periodically poled RbTiOAsO4 in a Nd:YVO4 laser 总被引:1,自引:0,他引:1
We describe a compact all-solid-state continuous-wave, singly resonant optical parametric oscillator (SRO) based on periodically poled RbTiOAsO4. The SRO is pumped at 1.064 microm by a Nd:YVO4 laser, which is itself pumped by a 3-W diode laser. Using the intracavity technique produced an oscillation threshold for the SRO of only 1.6 W (diode-laser power). For 3 W of diode pump power some 65 mW was obtained in the (nonresonant) idler (wavelength 3.52 microm). Temperature tuning over the range 10-100 degrees C resulted in tuning ranges of 1.52-1.54 and 3.41-3.54 microm for the signal and the idler waves, respectively. Importantly, relaxation oscillations were absent. 相似文献
12.
13.
The electrical resistivity of four Kondo systems, Au-(5 p.p.m. Fe), Au-(39 p.p.m. Fe), Au-(17 p.p.m. Mn) and Au-(50 p.p.m. Mn) has been measured in the temperature range 1.3–20 K at pressures up to 80 kbar. The Kondo temperature TK is found to increase initially with pressure at the rate of 1.1%/kbar for Au(Fe) and 6%/kbar for Au(Mn). The volume dependence of the effective exchange constant Jeff is derived. 相似文献
14.
A.L. Nikolaev 《哲学杂志》2013,93(12):1017-1033
Electrical resistivity recovery (RR) data for irradiated concentrated alloys typically consist of two inseparable parts, one resulting from defect annihilation and the other from short-range order (SRO) effects. These parts exhibit different behaviour and often follow opposite trends. Therefore, in this case, analysis of RR data within the conventional method is too complicated. A new approach to data analysis of such a two-component RR is proposed. The approach involves a new quantity, the difference RR (DRR), which is composed of RR dependences of two similar samples irradiated to different defect concentrations. It is shown that the SRO formation proper and the stages corresponding to the onset of long-range migration of Frenkel pair defects, formed in each part of RR, can be clearly related to certain features of the DRR plots. This interrelationship allows detecting and identifying these stages in each part of RR separately. The validity of the approach is illustrated by analysis of the available pairwise RR data for Fe–16Cr–20Ni and Fe–4Cr alloys. It makes it possible to detect the small contribution from the SRO formation to RR in Fe–4Cr, which we failed to observe previously. It is shown that stage III of Fe–4Cr, which has a negligible contribution to the part of RR induced by defect annihilation, is clearly observed in the part induced by SRO formation. 相似文献
15.
We report a stable, high-power, cw, mid-IR optical parametric oscillator using MgO-doped stoichiometric periodically poled LiTaO? (MgO:sPPLT) pumped by a Yb fiber laser at 1064 nm. The singly resonant oscillator (SRO), based on a 30 mm long crystal, is tunable over 430 nm from 3032 to 3462 nm and can generate as much as 5.5 W of mid-IR output power, with >4 W of over 60% of the tuning range and under reduced thermal effects, enabling room temperature operation. Idler power scaling measurements at ~3.3 μm are compared with an MgO-doped periodically poled LiNbO? cw SRO, confirming that MgO:sPPLT is an attractive material for multiwatt mid-IR generation. The idler output at 3299 nm exhibits a peak-to-peak power stability better than 12.8% over 5 h and frequency stability of ~1 GHz, while operating close to room temperature, and has a linewidth of ~0.2 nm, limited by the resolution of the wavemeter. The corresponding signal linewidth at 1570 nm is ~21 MHz. 相似文献
16.
The microstructure and electronic structure of silicon-rich oxide (SRO) films were investigated using transmission electron microscopy and electron energy loss spectroscopy as the main analytical techniques. The as-deposited SRO film was found to be a single phase SiO1.0, as suggested by its electronic structure characteristics determined by the valence electron energy loss spectrum. This single phase undergoes a continuous but incomplete phase decomposition to Si and SiO2 for films annealed between 300 and 1100°C. The resulting Si phase first appears as ~2?nm-diameter amorphous clusters which grow to larger sizes at higher annealing temperatures, but only crystallize at a critical temperature between 800 and 900°C. This cluster/matrix configuration of the SRO films is consistent with the appearance of the interface plasmon and its oscillator strength as a function of the nanoparticle size. Three separate stages were identified in the sequence of annealed films that were characterized by the presence of single-phase SiO, amorphous silicon nanoclusters, and silicon nanocrystals, respectively. The presence of amorphous silicon nanoclusters in the intermediate stage, the mean size of which can be controlled via annealing, may offer an alternative to silicon nanocrystal composites for optical applications. 相似文献
17.
Morenzoni E Luetkens H Prokscha T Suter A Vongtragool S Galli F Hesselberth MB Garifianov N Khasanov R 《Physical review letters》2008,100(14):147205
We have performed depth dependent muon-spin-rotation and -relaxation studies of the dynamics of single layer films of AuFe and CuMn spin glasses as a function of thickness and of its behavior as a function of distance from the vacuum interface (5-70 nm). A significant reduction in the muon-spin relaxation rate as a function of temperature with respect to the bulk material is observed when the muons are stopped near (5-10 nm) the surface of the sample. A similar reduction is observed for the whole sample if the thickness is reduced to, e.g., 20 nm and less. This reflects an increased impurity spin dynamics (incomplete freezing) close to the surface although the freezing temperature is only modestly affected by the dimensional reduction. 相似文献
18.
Observation of thermal-induced optical guiding and bistability in a mid-IR continuous-wave, singly resonant optical parametric oscillator 总被引:1,自引:0,他引:1
We report the observation of thermal-induced optical guiding and bistability in a mid-IR cw, singly resonant optical parametric oscillator (SRO) at approximately 3.2 microm. The SRO employs a MgO:PPLN crystal as the gain medium and a 1-nm-linewidth Yb-fiber laser at 1.064 microm as the pump source. As soon as the pump power reaches the thermal guiding threshold at 16.5 W, the SRO shows a step increase in the parametric efficiency by a factor of 2.5. At 25 W pump power, the SRO generated 5.3 and 1.2 W at 1.58 and 3.23 microm, respectively, with single-longitudinal-mode performance for the 3.23 microm radiation. 相似文献
19.
Yi-Chen Yeh Chun-Han Chiu Juh Tzeng Lue 《Applied Physics A: Materials Science & Processing》2009,94(4):923-926
We have observed an abnormal electron transport characteristic from the Ni–Mn–Ni triple-layered magnetic thin-films. Due to
the intercalated Mn ultra-thin interlayer, the magnetic domain structure and the electron transport characteristic differ
a lot from their original magnetic (Fe, Co, and Ni) films. As inspected by a magnetic force microscopy (MFM), we observed
the variation of the domain configuration with Mn interlayer thicknesses (for 1, 5, and 10 nm). Moreover, we also examined
and found that the direct current (DC) resistivity have no significant change as the current conducts from the current-in-wall
(CIW) to the current- perpendicular-to-wall (CPW), which are opposite to the results of single layered films. 相似文献
20.
It has been suggested that icosahedral short-range order (SRO) occurs in deeply undercooled melts of pure metallic elements. We report results of first-principles molecular dynamics simulations for stable and undercooled zirconium liquids. Our results emphasize the occurrence of a local order more complex than the icosahedral one. For stable liquid, the local order is interpreted on the basis of a competition between a polytetrahedral SRO and a bcc-type SRO. We also demonstrate that a bcc-type SRO increases with the degree of undercooling. 相似文献