Experimental approach on interfacial properties for Cr/Al double nanometer films under different temperature environment mode

In this paper, a typical interfacial structure sample between the materials Cr and Al was fabricated. To investigate the interfacial characteristics, the mechanical properties of the Cr/Al double interfacial structure were tested using the nanoindenter and the nanoscratch. The test results show that both of the values are easily influenced by the different depth h. In the nanoscratch experiment, the bilayer films are set off as two groups, one of which is tested after the thermal cycling load while the other is not. The test results show that the interface formation and the binding force in the interface can be easily influenced by the difference thermal characteristic of the each single film. The elastic modulus and the hardness of the bilayer films are investigated using the nanoindentation.     

The Effects of Thermal Treatments on Microstructure Phosphorus-Doped ZnO Layers Grown by Thermal Evaporation

The ZnO films doped with 3 wt% phosphorus (P) were produced by activating phosphorus doped ZnO (ZnO:P) thin films in oxygen (O₂) ambient at 600°C for 30, 60, 90 and 120 min, respectively. As-deposited films doped with phosphorus are highly conductive and n type. All the films showed p-type conduction after annealing, in an O₂ ambient atmosphere. The activation energies of the phosphorus dopant in the p-type ZnO under O₂ ambient gases indicate that phosphorus substitution on the O site yielded a deep level in the gap. With a further increase of the annealed durations, the crystalline quality of the ZnO:P sample is degraded. The best p-type ZnO:P film deposited at 600°C for 30 min shows a resistivity of 1.85 Ω cm and a relatively high hole concentration of 5.1 × 10¹⁷cm^–3 at room temperature. The films exhibit a polycrystalline hexagonal wurtzite structure without preferred orientation. The mean grain sizes are calculated to be about 60, 72, 78, 85 and 90 nm for the p-type ZnO films prepared at 600°C for 30, 60, 90 and 120 min, respectively. Room temperature photoluminescence (PL) spectra of the ZnO film exhibit two emission bands — paramount excitonic ultraviolet (UV) emission and weak deep level visible emission. The excellent emission from the film annealed at 600°C for 30 min is attributed to the good crystalline quality of the p-type ZnO film and the low rate of formation of intrinsic defects at such short duration. The visible emission consists of two components in the green range.     

Magnetic ordering above room temperature in the sigma-phase of Fe66V34

Magnetic properties of four sigma-phase Fe_100−xV_x samples with 34.4?x?55.1 were investigated by Mössbauer spectroscopy and magnetic measurements in the temperature interval 4.2-300 K. Four magnetic quantities, viz. hyperfine field, Curie temperature, magnetic moment and susceptibility, were determined. The sample containing 34.4 at% V was revealed to exhibit the largest values found up to now for the sigma-phase for average hyperfine field, 〈B〉=12.1 T, average magnetic moment per Fe atom, 〈μ〉=0.89 μ_B, and Curie temperature, T_C=315.3 K. The quantities were shown to be strongly correlated with each other. In particular, T_C is linearly correlated with 〈μ〉 with a slope of 406.5 K/μ_B, as well as 〈B〉 is so correlated with 〈μ〉, yielding 14.3 T/μ_B for the hyperfine coupling constant.     

Photoionization and electron–ion recombination of Cr I

Using the unified method, the inverse processes of photoionization and electron–ion recombination are studied in detail for neutral chromium, (), for the ground and excited states. The unified method based on close-coupling approximation and R-matrix method (i) subsumes both the radiative recombination (RR) and dielectronic recombination (DR) for the total rate and (ii) provides self-consistent sets of photoionization cross sections σ_PI and recombination rates α_RC. The present results show in total photoionization of the ground and excited states an enhancement in the background at the first excited threshold, state of the core. One prominent phot-excitation-of-core (PEC) resonance due to one dipole allowed transition (⁶S-⁶P^o) in the core is found in the photoionization cross sections of most of the valence electron excited states. Structures in the total and partial photoionization, for ionization into various excited core states and ground state only, respectively, are demonstrated. Results are presented for the septet and quintet states with n≤10 and l≤9 of Cr I. These states couple to the core ground state ⁶S and contribute to the recombination rates. State-specific recombination rates are also presented for these states and their features are illustrated. The total recombination rate shows two DR peaks, one at a relatively low temperature, at 630 K, and the other around 40,000 K. This can explain existence of neutral Cr in interstellar medium. Calculations were carried out in LS coupling using a close-coupling wave function expansion of 40 core states. The results illustrate the features in the radiative processes of Cr I and provide photoionization cross sections and recombination rates with good approximation for this astrophysically important ion.     

La0.4Ca0.6Mn1-xCrxO3（x=0.00,0.08）的磁电性质研究

用固相反应法制备了La0.4Ca0.6Mn1-xCrxO3（x=0.00,0.08）多晶样品,通过XRD谱、M-T曲线、ρ~T曲线、Lnρ-T-14曲线,研究Cr^3＋替代Mn3＋对La0.4Ca0.6MnO3电荷有序相及电输运性质的影响.实验结果表明：Cr^3＋替代Mn3＋对La0.4Ca0.6MnO3电荷有序相影响...     

外电场对SBN：Cr晶体二波耦合特性的影响及应用

对固液同成分SBN：Cr(Sr0.61Ba0.39Nb2O.6：Cr)晶体在外加直流电场作用下的光折变二波耦合特性及其应用进行了实验研究，分析了晶体的二波耦合强度增益 系数随外电场变化的趋势，并给出了实验测量结果.发现在适当的外电场作用下，晶体的光折变二波耦合增益和响 应速度可以得到一定程度的提高.进一步的研究表明，这种电场响应特性有助于改善SBN：Cr晶体的某些应用性能.利用该晶体通过光折变二波耦合非线性放大原理实现光学图像边沿增强时，通过给晶体沿轴向施加适当的外电场，可进一步提高图像边沿增强效果；在基于光 折变边沿增强预处理的联合变换相关器中，适当的外加电场可进一步改善联合变换相关器的相关识别性能. 关键词： SBN：Cr晶体 光折变二波耦合 边沿增强 联合变换相关器     

Nuclear and magnetic order in Y(Ni,Mn)O3 manganites by neutron powder diffraction

Neutron powder diffraction experiments performed on two selected compositions of the yttrium-based solid solution YNi_xMn_1−xO₃ clearly reveal a nuclear order between the Ni²⁺ and Mn⁴⁺ ions in the half-substituted compound YNi_0.50Mn_0.50O₃, so that the crystal structure is no longer described in the conventional orthorhombic Pbnm space group, but in the monoclinic P2₁/n, all over the investigated temperature range (1.5-300 K). However, both X-rays diagrams and neutron patterns of the YNi_0.25Mn_0.75O₃ phase are indexed in the Pbnm orthorhombic-like symmetry, indicating that the Mn and Ni ions are randomly distributed on the octahedral sites.In addition, neutron diffraction points out that the nature of the magnetic ordering is strongly connected to the structural properties. Whereas no long-range 3D-magnetic ordering was detected for the Pbnm YNi_0.25Mn_0.75O₃ phase, the YNi_0.50Mn_0.50O₃ compound exhibits a magnetic transition at The magnetic structure consists of two collinear Mn⁴⁺ and Ni²⁺ ferromagnetic layers (F_x0F_z magnetic configurations) with saturated magnetic moment values of 2.25(2) and 1.57(2) μ_B for Mn⁴⁺ and Ni²⁺, respectively, at 1.5 K.     

High-temperature thermoelectric properties of Ca3Co4O9+δ with Eu substitution

We have prepared polycrystalline Ca_3−xEu_xCo₄O_9+δ (x=0, 0.15, 0.3 and 0.45) samples using a sol-gel process followed by SPS sintering and investigated the Eu substitution effects on their high-temperature thermoelectric properties. With the Eu substitution, both the electrical resistivity and thermopower increase monotonously. This could be attributed to the decrease of hole concentrations by substitution of trivalent Eu³⁺ for divalent Ca²⁺. The Eu substituted samples (x=0.15, x=0.3) have lower thermal conductivity than Ca₃Co₄O_9+δ due to their lower electronic and lattice thermal conductivity. The dimensionless figure of merit ZT reaches 0.3 at 1000 K for the sample of Ca_2.7Eu_0.3Co₄O_9+δ.     

Phase separation effects in charge-ordered Pr<Subscript>0.5</Subscript>Ca<Subscript>0.5</Subscript>MnO<Subscript>3</Subscript> thin film

Compressed Pr_0.5Ca_0.5MnO₃ films (250 nm) deposited on LaAlO₃ have been studied by Electron Spin Resonance technique under high frequency and high magnetic field. We show evidences for the presence of a ferromagnetic phase (FM) embedded in the charge-order phase (CO), in form of thin layers which size depends on the strength and orientation of the magnetic field (parallel or perpendicular to the substrate plane). This FM phase presents an easy plane magnetic anisotropy with an anisotropy constant 100 times bigger than typical bulk values. When the magnetic field is applied perpendicular to the substrate plane, the FM phase is strongly coupled to the CO phase whereas for the parallel orientation it keeps an independent ferromagnetic resonance even when the CO phase becomes antiferromagnetic.     

Continuous and discontinuous precipitation in Fe-1 at.%Cr-1 at.%Mo alloy upon nitriding; crystal structure and composition of ternary nitrides

The internal nitriding response of a ternary Fe–1 at.%Cr–1 at.%Mo alloy, which serves as a model alloy for many CrMo-based steels, was investigated. The nitrides developing upon nitriding were characterised by X-ray diffraction, scanning electron microscopy, electron probe microanalysis, transmission electron microscopy and atom probe tomography. The developed nitrides were shown to be (metastable) ternary mixed nitrides, which exhibit complex morphological, compositional and structural transformations as a function of nitriding time. Analogous to nitrided binary Fe–Cr and Fe–Mo alloys, in ternary Fe–Cr–Mo alloys initially continuous precipitation of fine, coherent, cubic, NaCl-type nitride platelets, here with the composition (Cr_½,Mo_½)N_¾, occurs, with the broad faces of the platelets parallel to the {1?0?0}_α-Fe lattice planes. These nitrides undergo a discontinuous precipitation reaction upon prolonged nitriding leading to the development of lamellae of a novel, hexagonal CrMoN₂ nitride along {1?1?0}_α-Fe lattice planes, and of spherical cubic, NaCl-type (Cr,Mo)N _x nitride particles within the ferrite lamellae. The observed structural and compositional changes of the ternary nitrides have been attributed to the thermodynamic and kinetic constraints for the internal precipitation of (misfitting) nitrides in the ferrite matrix.