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991.
Nevenka Rajic Djordje Stojakovic Aleksander Recnik 《Journal of Physics and Chemistry of Solids》2011,72(6):800-803
Nanoparticles of NiO, ZnO and Cu2O crystallize when the Ni-, Zn- and Cu-exchanged natural clinoptilolite, respectively, are dehydrated by heating in air at 550 °C. The dehydration of Mn-exchanged clinoptilolite does not lead to the crystallization of manganese oxide but affects the crystallinity of the host clinoptilolite lattice, which becomes amorphous. The NiO, ZnO and Cu2O nanoparticles are found to be randomly dispersed in the clinoptilolite matrix. The particle size varies from 2 to 5 nm and exceeds the aperture of the clinoptilolite channel (approximately 0.4 nm), suggesting that the crystallization of the oxide phases takes place on the surfaces of clinoptilolite microcrystals. 相似文献
992.
A. Audzijonis R. Sereika R. ?altauskas A. R?za 《Journal of Physics and Chemistry of Solids》2011,72(12):1501-1505
Optical properties of BiSBr and BiSeBr crystals were investigated by the full potential linearized augmented plane wave (FP-LAPW) method with density-functional theory (DFT). The complex dielectric function and optical constants, such as optical absorption coefficient, refractive index, extinction coefficient, energy-loss spectrum and reflectivity, were calculated and compared in the energy range of 0–30 eV. Origin of anisotropic behavior of optical spectra was also discussed. The plasmon energy ?ωp was estimated to be 18 eV for BiSeBr and 20 eV for BiSBr crystal. 相似文献
993.
The microwave dielectric properties of La(Mg0.5−xCaxSn0.5)O3 ceramics were examined with a view to their exploitation for wireless communications. The La(Mg0.5−xCaxSn0.5)O3 ceramics were prepared by the conventional solid-state method with various sintering temperatures. The La(Mg0.5−xCaxSn0.5)O3 ceramics contained Ca2SnO4, CaSnO3, and La2O3. The amount of Ca2SnO4 increased with increasing sintering temperature. However, the relative amount of CaSnO3 decreased with increasing sintering temperature. An apparent density of 6.52 g/cm3, a dielectric constant (εr) of 20.2, a quality factor (Q×f) of 80,500 GHz, and a temperature coefficient of resonant frequency (τf) of −79 ppm/°C were obtained for La(Mg0.4Ca0.1Sn0.5)O3 ceramics that were sintered at 1500 °C for 4 h. 相似文献
994.
Toshiyuki Arakane Takafumi Sato Takenori Fujii 《Journal of Physics and Chemistry of Solids》2011,72(5):552-555
We have investigated three-dimensional electronic structure for NaxCoO2 (x=0.77 and 0.65) by high-resolution angle-resolved photoemission spectroscopy to study the origin of antiferromagnetic (AF) transition of highly doped NaxCoO2(x>0.75). The a1g large hole-like Fermi surface (FS) in x=0.77 shows distinct three-dimensionality along the kz direction, and a three-dimensional small electron pocket appears around Γ point, indicating strong inter-layer electronic correlation. On the other hand, x=0.65 sample does not show three-dimensional behavior. This result indicates that transition of FS as a function of band filling is closely related to the occurrence of the magnetic transition in highly doped NaxCoO2. 相似文献
995.
The electronic structure and the metal-insulator transition (MIT) of V2O3 are investigated in the framework of density functional theory and GGA+U. It is found that, both the insulating and metallic phases can be realized in rhombohedral structure by varying the on-site Coulomb interaction, and the MIT in V2O3 can take place without any structure phase transition. Our calculated energy gap (0.63 eV) agrees with experimental result very well. The metallic phase exhibits high spin (S=1) character, but it becomes S=1/2 in insulating phase. According to our analysis, the Mott-Hubbard and the charge-transfer induce the MIT together, and it supports the mechanism postulated by Tanaka (2002) [11]. 相似文献
996.
A.C. Galca V. StancuM.A. Husanu C. DragoiN.G. Gheorghe L. TrupinaM. Enculescu E. Vasile 《Applied Surface Science》2011,257(14):5938-5943
The paper presents the influence of pulsed laser deposition (PLD) parameters on the structural and optical properties of PZT thin films grown on platinum substrate. X-ray diffraction (XRD), spectroscopic ellipsometry (SE) and X-ray photoelectron spectroscopy (XPS) are used to determine the thin film properties. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) are employed to get additional information. By changing the distance between target and substrate, different crystalline orientations of PZT are obtained. The thin film thickness and its roughness, as well as the refractive index are also influenced by the chosen distance. 相似文献
997.
998.
Pure TiO2 and nitrogen doped titanium dioxide (N-TiO2) thin films were prepared by sol-gel method through spin coating on soda lime glass substrates. TiCl4 and urea were used as Ti and N sources in the sol. XRD results showed nitrogen doping has retarded anatase to rutile phase transformation. The doping also leads to a decrease in roughness of the samples from 4 nm (TiO2) to 1 nm (N-TiO2). However, surface analysis by statistical methods reveals that both surfaces have self-affine structure. Optical band gap of thin films was shifted from 3.65 eV (TiO2) to 3.47 eV (N-TiO2). Hydrophilic conversion and photocatalytic degradation properties of thin films were investigated and exhibited that N-TiO2 thin film has more preferable hydrophilicity and photocatalytic properties under UV illumination. 相似文献
999.
Xinrui Miao Li XuChenyi Liao Zhuomin LiJian Zhou Wenli Deng 《Applied Surface Science》2011,257(10):4559-4565
Self-assembled monolayers of hexadecyl palmitate (HP) and 3,3′-thiodipropionic acid di-n-octadecyl ester (TADE) physisorbed on highly oriented pyrolytic graphite (HOPG) are investigated using scanning tunneling microscope (STM) and computer simulation. Both molecules form alkane-like linear shapes to maximize the interactions with substrate when they adsorb on HOPG surface. The HP molecules self-assemble into lamellae with the chain-trough angle of 48°, which is the result of a shifting 3/2 units from the adjacent molecule in a lamella. Based on the simulation insights combined with STM images, we confirm that a perpendicular orientation appears in which the HP molecular backbone is rotated 90° with respect to the substrate such that the carbonyl points away from the HOPG surface. TADE molecules form three kinds of configurations with chain-trough angles of 90°, 72° and 60° by shifting 0, 1/2 and 1 units from their adjacent molecules, respectively. The bright stripes in STM images reveal the electron density distribution of the part between two ester groups. The energy differences of three TADE adsorption configurations by molecular mechanics (MM) simulation are used to explain the structural coexistence phenomenon. It is also shown that lattice match between alkyl chain of molecules and HOPG substrate could change molecular conformation upon self-assembly. 相似文献
1000.
B. HuB.Y. Man C. YangM. Liu C.S. ChenX.G. Gao S.C. XuC.C. Wang Z.C. Sun 《Applied Surface Science》2011,258(1):525-529
Mn-doped GaN films (Ga1−xMnxN) were grown on sapphire (0 0 0 1) using Laser assisted Molecular Beam Epitaxy (LMBE). High-quality nanocrystalline Ga1−xMnxN films with different Mn concentration were then obtained by thermal annealing treatment for 30 min in the ammonia atmosphere. Mn ions were incorporated into the wurtzite structure of the host lattice by substituting the Ga sites with Mn3+ due to the thermal treatment. Mn3+, which is confirmed by XPS analysis, is believed to be the decisive factor in the origin of room-temperature ferromagnetism. The better room-temperature ferromagnetism is given with the higher Mn3+ concentration. The bound magnetic polarons (BMP) theory can be used to prove our room-temperature ferromagnetic properties. The film with the maximum concentration of Mn3+ presents strongest ferromagnetic signal at annealing temperature 950 °C. Higher annealing temperature (such as 1150 °C) is not proper because of the second phase MnxGay formation. 相似文献