Papers by Keyword: Lattice Distortion

Abstract: Thermal oxidation of 4H-SiC to grow native-oxide SiO₂ is always followed by the generation of crystal defects and lattice distortion. We studied the relaxation of this distorted lattice on thermally-oxidized 4H-SiC surface by performing annealing process with several conditions. The surface distortion could be relaxed partially by annealing under argon, nitrogen monoxide, and H₂O gases, confirmed by in-plane X-ray diffractometer. This surface relaxation is possibly induced by the release of oxygen-related defects, as confirmed by thermal desorption analysis. The surface distortion caused by thermal oxidation is due to the existence of oxygen in 4H-SiC lattice, while the relaxation is caused by the migration of the oxygen-related defect structure, and emitted from 4H-SiC surface region as CO molecule.

Abstract: Ceria and zirconia are very important for their thermal, mechanical, and chemical stability, and their thin films have attracted much attention for applications such as buffer layers for growing electric devices, thermal-shield or optical coatings, corrosion-resistant coatings, oxygen sensors and ionic conductors for fuel cells. To investigate and control the thin film orientation and phase is important to improve those performances. In this study, the reciprocal space maps of CeO₂/YSZ/Si(001) were obtained at high temperature by adding a heater to the sample stage. CeO₂ and YSZ thin films were epitaxially grown samples. By measuring lattice constants at high temperature, it was conducted that axes of CeO₂ and YSZ thin films parallel to the substrate surface showed smaller thermal coefficients than bulk reference and axes perpendicular to the surface showed larger thermal coefficients due to the underlayer and Si substrate. The distortion rate of the lattice of each film was small around at the film deposition temperature. And it could be controled the lattice parameter at the film surface by the film thickness. Therefore, when another thin film, for example, SrTiO₃ is deposited on the CeO₂ layer, the lattice change of CeO₂ with increasing temperature may differ from that before depositing the top layer.

Abstract: The microstructure evolution and properties of Al-matrix in homogenized 7A56 alloy were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), electrical conductivity and hardness test. The second phases in as-cast 7A56 alloy consisted of AlZnMgCu, Al₂Cu and Al₇Cu₂Fe. With the homogenization temperature increasing, more non-equilibrium phase AlZnMgCu was dissolved into Al-matrix. The diffusion of alloying elements from AlZnMgCu phase into Al-matrix leads to a decrease of electrical conductivity and an increase of hardness. The lattice constant of α-Al has an increases of 0.0019 Å, 0.0032 Å and 0.0053 Å after 380°C/24h,430°C/24h,and 470°C/24 h treatment,respectively.

Abstract: Intermediate vector polysuccinimide (PSI) was prepared by polymerization of malefic acid and ammonia at 180°Cin this article. Hydrophilic polyaspartic acid (PASP) derivative was prepared from amino-sulfonic and PSI; Lipophilic PASP derivative was prepared from PSI and diisopropylamine. Their scale inhibition rates of calcium carbonate were evaluated by static scale experiments. The inhibition rate of calcium carbonate was 90.2% when n(amino-sulfonic): n(PSI) =1:14 and the dosage of pharmaceutical was 12mg / L. The inhibition rate of calcium carbonate was 87.6% when n(diisopropylamine):n(PSI)=1:8 and the dosage of pharmaceutical was 15mg /L. The calcium carbonate that collected from static state experiments was analysised by scanning electron microscope (SEM). The results showed that polyaspartic acid derivatives were synthesized which had the best overall performance when n (amino-sulfonic): n (PSI) = 1:14.

Abstract: M2052 alloys with various aging treatments are obtained in order to investigate the relationship between aging treatment and damping capacity by the torsion pendulum, X-Ray Diffraction (XRD) and Transmission Electron Microscope (TEM) methods. The results show that M2052 can obtain high damping capacity (δ>0.2) when aged at a range from 400°C to 450°C, and the damping capacity after aged at a lower temperature is higher than that aged at a higher temperature for the maximum values. TEM and XRD results show that fcc-fct transformation occurs after aging treatment. The volumes of fct structures are one of reason to affect the damping capacity in M2052 alloy. The better understanding aging treatment could promote the applications of M2052 alloy.

Abstract: In order to test whether the crystallinity and orientation of ramie fibers have changed after they are treated by the lattice distortion modification processing technology, this paper does some experiments on it. Firstly, process ramie fibers by the lattice distortion modification processing equipment. Then use X-ray diffraction method to determine the crystallinity and orientation of pristine and modified ramie fibers. Finally analyse the effect of lattice distortion modification processing on the lattice structure of ramie fiber. The experimental results show that the lattice structure of ramie fiber has changed after modification processing, with crystallinity, grain size decreasing obviously and orientation slight descent, which make ramie fibers appear softer and more puffy from macrocosmic perspective.

Abstract: For cotton/linen fibers, yarns and other textile raw materials have natural weak points such as rough, easy to wrinkle and shrink, poor dyeability and so on, which are bad for clothing, this paper develops a lattice distortion modification processing technology of cotton/linen fibers and yarns, including the modification equipment and the process flow. After processed by this new modification technology, the performances of cotton/linen fibers and yarns, like softness, smoothness, fluffiness and dyeing properties improved significantly, which meet the product's quality requirements. Therefore, this lattice distortion processing technology can be popularized as a basic technology in the textile field.

Abstract: Metal ions doped complex cobalt blue pigments are prepared by homogeneous precipitation, to investigate the effects of doping ions Zn²⁺ ，Mg²⁺ ，Ni²⁺ and Y ³⁺ on some properties of the doped complex cobalt blue pigments, such as crystal structure, color, shading power and temperature resistance. Studies have shown that doping have little effect on the spinel crystal type and temperature resistance of the pigments ; ionic radius differences between doping ions and Co^{2 +} cause lattice distortion and changes of lattice constant , thus affecting the ligand state spaces of Co^{2 +} ion, color and shading power of complex cobalt blue pigment. The lattice constant of Zn^{2 +} doped complex cobalt blue becomes larger with the increasing amount of Zn^{2 +} ; while doping Mg^{2 +}and Ni^{2 +} , the crystal lattice constants become smaller; when doping with Y^{3 +} , Y^{3 +} ions enter into CoAl₂O₄ lattice, replacing some hexa-coordinate octahedral gap of Al^{3 +} , ionic radius differences between Y^{3 +} and Al³⁺cause lattice distortion, when doping amount of Y ^{3 +} increases to a certain extent, the phase in the form of Y₂O₃ will be generated and it will maybe form a kind of CoY_xAl_2-xO₄- Y₂O₃ solid solution instead of the complete spinel structure.

Abstract: We investigated the electrical properties of the perovskite R(Cr,Mn)O₃ (where R is selected from various rare earth elements and Y), which is suitable for use in negative temperature coefficient (NTC) thermistors. The substitutions of Mn for Cr in La(Cr,Mn)O₃ and larger ions for R³⁺ decreased both the resistivities (r) and thermistor constants (B values) estimated from measurements at 25°C and 50°C according to r = r₀exp(B/T). The activation energies of the carrier number (E_g) and carrier mobility (W_H) were estimated by measuring the thermoelectric power and resistivity. A change in W_H corresponded to a change in the B value. We discussed the relationship between the grand state electronic configuration of the M³⁺ ions and the local lattice distortion around the M³⁺ ions. The change in W_H could be qualitatively linked to the M3d– O2p transfer energy, which is corresponding to the hybridization between the M3d and O2p orbital (M: transition metal elements, O: oxygen).

Abstract: Effect of the lattice distortion of the main crystal mullite, addition of copper mine tailing and the firing schedule on the infrared properties were studied. The study revealed that the higher lattice distortion is, the higher infrared emissivity of ceramic tiles is. The addition of raw materials containing iron and other elemental impurities could form the solid solution in the body what promote the degree of lattice distortion of main crystal which affects the infrared emissivity of the ceramic tiles. With the increasing of firing temperature, the degree of lattice distortion of main crystals will decrease and the infrared properties also decrease.