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1.
G. J. Huang J. B. Wang X. L. Zhong G. C. Zhou H. L. Yan 《Journal of Materials Science》2007,42(15):6464-6468
In this paper, Ni-doped ZnO (Zn1−x
Ni
x
O, in which 0 ≤ x ≤ 0.05) diluted magnetic semiconductors nanoparticles are prepared by an ultrasonic assisted sol–gel process. Transmission
electron microscopy shows sphere-like nanoparticles with an average size of about 25 nm. From the analysis of X-ray diffraction,
the Ni-doped ZnO nanoparticles are identified to be a wurtzite structure, but impurity phases are observed when the Ni content
x reaches 0.05. Sample structures are further studied by Raman spectra, from which a broad and strong Raman band in the range
of 500–600 cm−1 is observed in Zn1−x
Ni
x
O. With the increment of x, wurtzite structures degrade gradually. The magnetic properties are measured using superconducting quantum interference device
at room temperature; the Zn1−x
Ni
x
O (x ≤ 0.02) nanoparticles show ferromagnetism. However, for the sample of Zn0.95Ni0.05O, paramagnetism is observed, which may be ascribed to ferromagnetic–antiferromagnetic competition. 相似文献
2.
Guo Zhou Shibing Ni Xiaolei Sun Xinghui Wang Qi Wang Deyan He 《Journal of Materials Science: Materials in Electronics》2011,22(2):174-178
Sn1−x
Ni
x
O2 nanostructures such as nanocubes, nanospheres and hollow spheres were synthesized by a simple hydrothermal method. Room temperature
photoluminescence spectra of the as-synthesized samples display a strong yellow emission at about 600 nm and a weak blue emission
at about 430 nm. The as-prepared and annealed Sn1−x
Ni
x
O2 (x = 0, 0.01, 0.02, 0.04) were characterized by X-ray diffraction, field emission scanning electron microscopy, Raman spectrum,
UV–Vis absorption spectra, and room temperature photoluminescence spectra. By investigating the relationship between the Raman
band centered at 560 cm−1 and the photoluminescence of the samples, we suggest that the broad yellow emission and weak blue emission primarily originate
from singly ionized oxygen vacancies and tin interstitials, respectively. 相似文献
3.
The technologically important Cd1−xNixSe thin films with variable compositions (0 ≤ x ≤ 1) have been developed by a chemical deposition method. The structural,
compositional, optical and electrical properties were studied by X-ray diffraction, Scanning electron microscopy, Atomic absorption
spectroscopy, UV–visible double beam spectrophotometer and d.c. two probe method. XRD studies indicate polycrystalline in
nature with hexagonal phase for all the samples. The lattice constants decrease with increase in nickel content in CdSe host
lattice. The surface morphology study of all samples reveals uniform and spherical grains. An optical study of the samples
shows that band gap value decreases with nickel content. Electrical measurements depict semiconducting properties of all samples. 相似文献
4.
Yue Zheng Chunsheng Shi Naiqin Zhao Xiwen Du Jiajun Li 《Journal of Materials Science》2010,45(24):6657-6660
SiC/ZnO nanocomposites were prepared by radio frequency alternate sputtering followed by annealing in N2 ambient. Well-crystallized ZnO matrix was obtained after annealed at 750 °C according to X-ray diffractometer patterns. Transmission
electron microscopy analyses indicated that the SiC thin layer aggregated to form SiC nanoclusters with the average size of
7.2 nm when the annealing temperature was 600 °C. When the annealing temperatures increased above 900 °C, some of the SiC
nanoclusters changed into SiC nanocrystals and surfacial atoms of the SiC nanoparticles were surrounded by a layer of SiO
x
(x ≤ 2) according to the Fourier transform infrared spectrums. The SiC/ZnO nanocomposites annealed at 750 °C exhibit strong
photoluminescence bands ranging from 250 to 600 nm. UV light originates from the near band edge emission of ZnO and the blue
emission peaked at around 465 nm (2.7 eV) may be due to the formation of emission centers caused by the defects in Si–O network,
while the green-emission peak at around 550 nm (2.3 eV) may be attributed to the deep level recombination luminescence caused
by the vacancies of oxygen and zinc. 相似文献
5.
Ahmet Ekicibil G?kmen Bulun Selda K?l?? ?etin Zafer Dikmen ?nder Orhun Tezer F?rat Kerim K?yma? 《Journal of Superconductivity and Novel Magnetism》2012,25(2):435-440
In this study the origin of ferromagnetism in ZnO-based bulk systems has been investigated using Ni-doped ZnO samples, Zn1−x
Ni
x
O with 0.25≤x≤0.50, prepared by solid-state reactions. The structural characterizations indicated that the Ni2+ ions almost uniformly distributed in all the samples, and the samples have hexagonal wurtzite structure; however, when x is increased toward 0.50, a new NiO phase is formed. A ferromagnetism (FM) has been observed for all the samples at and below
the room temperature. In other words, the room temperature results of (M–H) curves show that the FM observed is intrinsic for all the Ni-doped ZnO samples. However, the saturated magnetizations decrease
gradually with increasing Ni concentration. This indicates that, in addition to FM, the excessive doping of Ni in ZnO also
causes an antiferromagnetic (AFM) contribution which increases with increasing Ni amount. This result is also supported by
the magnetization against temperature measurements. Furthermore, the trend of the ac-susceptibility (χ) versus temperature curves, measured under an ac-magnetic field of 100 Oe, also support our conclusion about the antiferromagnetic
contribution to ferromagnetism in our samples. 相似文献
6.
K. Sambath M. Saroja M. Venkatachalam K. Rajendran N. Muthukumarasamy 《Journal of Materials Science: Materials in Electronics》2012,23(2):431-436
ZnO nanostructures have been synthesized in a controlled manner by varying the pH of the precursor solution using hydrothermal
technique. The morphological changes of the prepared ZnO nanostructures have been investigated in the range of pH 5–10. Radial
hexagonal rod-like shape is formed at lower pH values of 5 and 6 whereas, flower-like shape is obtained for higher pH values
of 9 and 10. Flake-like structure is observed at moderate pH of 8. The prepared ZnO nanostructures have been characterized
using X-ray diffraction technique (XRD), energy dispersive X-ray analysis, scanning electron microscope and FTIR spectroscopy.
XRD results show that the prepared ZnO nanostructures exhibit hexagonal wurtzite structure. The growth mechanism suggests
that the supersaturation of the precursor results in various nucleation habits, which induce the formation of ZnO nanostructures
with different morphologies. UV–Vis spectroscopy and photoluminescence were applied to study the optical properties. The photoluminescence
spectrum demonstrated two emission bands, a near band edge emission in the UV region and a strong deep band emission in the
visible region. The change in pH from 5 to 10 results in band gap variations of 3.47–3.97 eV and blue-shift in the peak emission
of visible PL from 560 to 460 nm. 相似文献
7.
R. Gopalakrishnan S. Muthukumaran 《Journal of Materials Science: Materials in Electronics》2013,24(4):1069-1080
Zn1?xNixO (x = 0, 0.01, 0.02, 0.03, 0.04 and 0.05) nanoclusters have been successfully synthesized by co-precipitation method. The synthesized samples have been characterized by powder X-ray diffraction, energy dispersive X-ray spectra, UV–visible spectrophotometer and Fourier transform infrared spectroscopy. The XRD and SEM measurements reveal that the prepared undoped and Ni-doped nanoclusters have different microstructure without changing a hexagonal wurtzite structure. The calculated average crystalline size from XRD measurement decreases from 37.5 to 26.6 nm for x = 0 to 0.05 which was confirmed by SEM micrographs. The change in lattice parameters, micro-strain, shift of XRD peaks and the blue shift of energy gap from 3.18 to 3.33 eV (ΔEg = 0.15 eV) for Ni = 0–0.02 and red shift of Eg from 3.33 to 3.14 eV (ΔEg = 0.19 eV) for Ni = 0.02 to 0.05 reveal the substitution of Ni2+ ions into Zn–O lattice. The presence of functional groups and the chemical bonding are confirmed by FTIR spectra. The shift of NBE UV emission between 374 and 395 nm, the shift of green band emission between 517 and 531 nm, the change in intensity and the broadening effect in the photoluminescence spectra confirms the substitution of Ni2+ ions into the Zn–O lattice. Ni-doped ZnO system shows a great pledge for the fabrication of nano-optoelectronic devices like tunable light emitting diode in the near future. 相似文献
8.
Jing Zhao Xiaoqin Yan Yang Lei Yunhua Huang Yue Zhang 《Materials Research Bulletin》2011,46(8):1207-1210
The one-dimensional (1D) Zn1−xNixO (x = 0, 0.02, 0.05, 0.10) nanorods have been synthesized by a simple hydrothermal method. New bands show at ∼130 cm−1 in the Raman spectra of Ni-doped ZnO nanorods and their relative intensity depends on the doping concentration of nickel. The optical band gap of the ZnO nanorods have been tuned by Ni-doping, which is revealed by absorption spectra. The photocatalytic activity of Zn1−xNixO was studied by comparing the degradation rate of rhodamine B (RB) under UV-light irradiation. It was found that Zn0.95Ni0.05O exhibited the highest photocatalytic degradation efficiency among the samples. 相似文献
9.
Rui Bin Zhao Deng Lu Hou Jun Mei Guo Cong Mian Zhen Gui De Tang 《Journal of Superconductivity and Novel Magnetism》2010,23(7):1261-1265
Zn1−x
Ni
x
O (x=0.1%, 0.4%, 0.7%, 1.0%) powders were prepared using the sol-gel technique, and the structural, optical, and magnetic properties
of the samples were investigated. X-ray diffraction measurements show that all samples have a wurtzite structure and that
the c-axis lattice constant decreases as the Ni content increases. X-ray photoelectron spectroscopy studies reveal that the doped
Ni ions are in divalent states in all samples. Optical absorption spectra show that the band energy of Zn1−x
Ni
x
O powders decreases with increasing Ni concentration. Photoluminescence measurements of Zn1−x
Ni
x
O show a broad peak at a wavelength centered at about 467 nm which indicates the presence of a fraction of defects in ZnO.
The room temperature ferromagnetism observed in all samples is intrinsic in nature. 相似文献
10.
The outline of magnetic interactions in DMSs was determined using Zn1−x
Co
x
O particles, where “x” was changed as 0.01, 0.05, 0.10, 0.15, and 0.20. The syntheses were accomplished though mechanical milling and thermal treatment,
known as solid state reaction. The formation of each synthesis was monitored by differential thermal and thermo gravimetric
methods (DT-TGA). Substitution of Co2+ ions with Zn2+ host atoms in a ZnO lattice was analyzed using X-ray diffraction (XRD) patterns, Fourier transform infrared (FT-IR) spectroscopy,
energy dispersive X-ray spectrometry (EDS) data, transmission electron microscopy (TEM) figures, scanning area electron diffraction
(SAED) patterns, and X-ray photo spectroscopy (XPS) spectrum. The measured Co contents in ZnO lattice were found to be ~0.7%
less than the expected result. In addition to Zn1−x
Co
x
O particles, tungsten (W) contaminations were noticed in the variations of 1.5 ± 0.2%, as originating from the abrasion between
the miller and balls. The progressive replacement of Co2+ with Zn2+ host ions in ZnO lattice from 1% to 20% decreased the band edge from 3.03 ± 0.01 eV to 2.95 ± 0.01 eV, respectively. Co doping
has also changed the magnetic nature of the ZnO. Although having both interactions (ferromagnetic and antiferromagnetic),
dominance of ferromagnetic behavior was only observed for Zn0.99Co0.01O with the coercivity of ~154 ± 50 Oe and positive Curie–Weiss temperature as 79 ± 1 K. However, the calculated
\frac2J\textex k\textB {\frac{{2J_{\text{ex}} }}{{k_{\text{B}} }}} values have proved that the higher Co2+ concentrations in ZnO lattice have increased the efficiency of antiferromagnetic interactions. Surprisingly, there was no
rapid change at
\frac2J\textex k\textB {\frac{{2J_{\text{ex}} }}{{k_{\text{B}} }}} values as mentioned in previous works. 相似文献
11.
L. B. Duan X. R. Zhao J. M. Liu W. C. Geng H. N. Sun H. Y. Xie 《Journal of Materials Science: Materials in Electronics》2012,23(5):1016-1021
Al-doped Zn1−x
Mg
x
O and Zn1−y
Cd
y
O thin films were prepared on glass substrates by sol–gel method. The codoping thin films showed preferential c-axis orientation, and the lattice constant c evaluated from the shift of the position of (002) peak displayed an increasing evolution from x = 8 at.% to y = 8 at.%, indicating a roughly statistical substitution of Mg2+ and Cd2+ for Zn2+ in their solid solution. The effects of narrowing and widening band gap (E
g) on conductivity of (Cd, Al) and (Mg, Al) codoped ZnO thin films were simultaneously investigated using transmission spectra
and electrical measurements. The transmittances of these films are obviously decreased by vacuum annealing to 50–60%. However,
the carrier concentration and Hall mobility both increase, and resistivity decreases with narrowing band gap in 1 at.% Al-doped
Zn1−x
Mg
x
O and Zn1−y
Cd
y
O thin films from x = 8 at.% to y = 8 at.%. It is revealed that the conductivity of Al-doped ZnO thin films could be enhanced by this simple band gap modification. 相似文献
12.
Huan Deng Hongmei Deng Pingxiong Yang Junhao Chu 《Journal of Materials Science: Materials in Electronics》2012,23(6):1215-1218
Multiferroic BiCr
x
Fe1−x
O3 (BCFO) (0 ≤ x ≤ 0.12) thin films were fabricated on silicon substrates by sol–gel technique. The microstructure and properties of the films
are characterized using X-ray diffraction, spectroscopic ellipsometry, micro-Raman spectrometry and a Modular Control system.
The BCFO films are the rhombohedral structure with the Cr content up to 7%. Raman scattering spectra of the BCFO films demonstrate
the transformation of structure with the Cr content exceeding 10%. The band gap of the BCFO films is from 2.53 to 2.82 eV
with the Cr content being from 0 to 12%. The magnetization of the BCFO films is significantly enhanced with the increasing
of the Cr content. 相似文献
13.
D. B. Dhwajam J. K. Thomas K. Joy Sam Solomon 《Journal of Materials Science: Materials in Electronics》2011,22(4):384-388
The xPrTiTaO6 (1 − x) YTiNbO6 dielectric ceramic composites are fabricated through the solid state ceramic route. The compositions are calcined in the
temperature range 1,200–1,260 °C and sintered in the range 1,350–1,410 °C. Structural analysis of the materials is done using
X-ray Diffraction analysis. The composites contain both aeschynite and euxenite orthorhombic phases. The surface morphology
of the sintered pellets is examined by scanning electron microscopy. The dielectric constant, conductance and loss factor
are measured in the radio frequency region. The UV–visible spectra are recorded and the band gap is calculated. The photoluminescence
spectra of the compositions are recorded and the transitions causing emission are identified. The elemental composition of
the composites is confirmed using energy dispersive spectroscopy. The materials are suitable for substrate and optoelectronic
applications. 相似文献
14.
Jia Li Jin-Hua Huang Wei-Jie Song Rui-Qin Tan Ye Yang Xiao-Min Li 《Journal of Materials Science: Materials in Electronics》2010,21(5):529-533
Mg
x
Zn1−x
O (0 ≤ x ≤ 0.35) thin films have been deposited by sol–gel technique and the composition related structural, electrical, and optical
properties are investigated. All the films have hexagonal wurtzite structure and the separation of MgO phase occurs when x = 0.3 and 0.35. With the increase of Mg content, the densification of the films decrease and band gap values increase. The
maximum band gap value reaches 3.56 eV when x = 0.15. After Mg doping the conductivities of the Mg
x
Zn1−x
O films are reduced greatly and the electrical current–voltage (I–V) characteristics show nonlinearity for x > 0.15. 相似文献
15.
J. Mera C. Córdoba J. Benavidez O. Paredes J. Doria A. Gómez C. Sanchez C. Paucar O. Morán 《Journal of Materials Science》2010,45(19):5398-5405
Polymeric precursor method (Pechini) was employed to fabricate single- and multilayers of Zn1−x
Mn
x
O (x = 0–0.3) on glass substrates. X-ray diffraction measurements revealed that crystal structure of Zn1−x
Mn
x
O multilayers is the typical hexagonal würzite structure of pristine ZnO. A reduced peak intensity and widened full width
half maximum (FWHM) value of prominent peaks suggested that the Mn2+ ions have substituted the Zn2+ ion without changing the würzite structure of pristine ZnO up to Mn concentrations x ≤ 0.2. A distinct redshift of the absorption edge was observed as the Mn concentration x was increased. Additionally, the absorption edge was less sharp due, probably, to s–d and p–d interactions, which give rise to band gap bowing. Nevertheless, amorphous states appearing in the band gap as a consequence
of reduced crystallinity may also be responsible for the shrinking of the band gap in this material. Interestingly, the field
dependence of the magnetization showed typical paramagnetic behavior for all the chosen Mn concentrations with no evidence
of ferromagnetic ordering. Probably, the absence of ferromagnetism in the studied Zn1−x
Mn
x
O films is strongly related to defects (say Mn impurities at the interface between nano-crystallites) in ZnO due to partial
substitution of host Zn ions by Mn ions. 相似文献
16.
Xuming Pang Jinhao Qiu Kongjun Zhu Jianzhou Du 《Journal of Materials Science: Materials in Electronics》2012,23(5):1083-1086
K0.5Na0.5NbO3–x ZnO (KNN–xZn) lead-free ceramics have been prepared using the conventional sintering technique and the effects of ZnO addition on the
phase structure and piezoelectric properties of the ceramics have been studied. Our results reveal that a small amount of
ZnO can improve the density of the ceramics effectively. Because of the high density and ZnO doping effects, the piezoelectric
and dielectric properties of the ceramics are improved considerably. The good piezoelectric and dielectric properties of d
33 = 114 pC/N, k
p = 0.36, ε
r = 395, and Q
m = 68 were obtained for the KNN ceramics doped with 1 mol% ZnO. Therefore, the KNN-1.0 mol%Zn ceramics is a good candidate
for lead-free piezoelectric application. 相似文献
17.
Lan Wei Peng Xingping Liu Xueqin He Zhiwei Wang Yinyue 《Frontiers of Materials Science in China》2007,1(1):88-91
Zinc oxide (ZnO) thin films were deposited on (100) Si substrates by sol-gel technique. Zinc acetate was used as the precursor
material. The effect of different annealing atmospheres and annealing temperatures on composition, structural and optical
properties of ZnO thin films was investigated by using Fourier transform infrared spectroscopy, X-ray diffraction, atomic
force microscopy and photoluminescence (PL), respectively. At an annealing temperature of 400°C in N2 for 2 h, dried gel films were propitious to undergo structural relaxation and grow ZnO grains. ZnO thin film annealed at
400°C in N2 for 2 h exhibited the optimal structure and PL property, and the grain size and the lattice constants of the film were calculated
(41.6 nm, a = 3.253 ? and c = 5.210 ?). Moreover, a green emission around 495 nm was observed in the PL spectra owing to the oxygen vacancies located
at the surface of ZnO grains. With increasing annealing temperature, both the amount of the grown ZnO and the specific surface
area of the grains decrease, which jointly weaken the green emission.
Translated from Journal of Lanzhou University (Natural Science), 2006, 42(1): 67–71 [译自: 兰州大学学报 (自然科学版)] 相似文献
18.
Nanophotocatalysts LaFe1−x
Zn
x
O3 (x = 0, 0.05, 0.1, 0.3, 0.5) were successfully prepared by sol–gel auto-combustion method. The samples were characterized by
X-ray diffraction (XRD), ultraviolet/visible absorption spectra (UV–vis), scanning electron microscopy (SEM), and transmission
electron microscopy (TEM). The photocatalytic activities of the prepared samples were investigated for the photodegradation
of methylene blue (MB). The results show that the lattice constant of LaFe1−x
Zn
x
O3 nanocrystals increases due to the substitution of Zn for Fe, which leads to the lattice distortion. The absorption edges
of Zn-doped LaFeO3 display a red shift with a significant absorption between 400 and 500 nm. Doping with the Zn ions enhances the photodegradation
rate of LaFeO3 for MB. The LaFe0.7Zn0.3O3 particles are spherical with mean grain size of about 20–30 nm, which exhibits the highest degradation rate of 75% under
irradiation time of 150 min. 相似文献
19.
Suresh Kumar Virender Kundu Anil Vohra S. K. Chakarvarti 《Journal of Materials Science: Materials in Electronics》2011,22(8):995-999
Using polycarbonate track-etch membranes (Whatman), copper telluride (Cu1.75Te) nanowires of diameter 100 nm and 50 nm have been synthesized electrochemically via template-assisted electrodeposition
technique on indium tin oxide (ITO) coated glass from aqueous acidic solution of copper (II) sulphate (CuSO4·5H2O) and tellurium oxide (TeO2) at room temperature (30 °C). Scanning electron microscopy (SEM) reveals the morphology of the nanowires having uniform diameter
equal to the diameter of the template used. X-ray diffraction (XRD) pattern showed the structure corresponding to the hexagonal
structure of copper telluride and single-crystalline. Using UV–visible spectrometry, the optical band gap of copper telluride
nanowires was found to be 3.092 eV for 100 nm and 3.230 eV for 50 nm diameters. The photoluminescence (PL) studies shows higher
intensity and broad spectrum in the blue region (450–475 nm) of visible light spectrum. 相似文献
20.
S. V. Kondratenko O. V. Vakulenko Yu. N. Kozyrev M. Yu. Rubezhanska A. G. Naumovets A. S. Nikolenko V. S. Lysenko V. V. Strelchuk C. Teichert 《Journal of Materials Science》2011,46(17):5737-5742
Interband optical transitions in multilayer heterostructures with SiGe nanoislands were investigated using photocurrent spectroscopy
and photo-emf. The n-p heterostructures containing Ge nanoislands in the area of the potential barrier were prepared by molecular-beam epitaxy at
the temperature about 500 °C. It was shown that electron transitions from the ground state of the valence band in a nanoislands
to the conduction band of Si surrounding made the main contribution into the vertical photo-emf in the range 0.75–1.05 eV,
which is below the interband absorption edge of Si. The lateral photoconductivity observed in the range 0.63–0.8 eV at 77 K
can be attributed to indirect interband transitions from the ground state of a nanoisland to L-state of the conduction band of a nanoisland. Analysis of Raman scattering spectra revealed that the Ge composition x in a nanoisland is about 0.87, while elastic deformation value amounts to ε
xx
= −0.016. The calculated energies of interband transitions from the ground state of a nanoisland to the conduction band of
Si surrounding (0.63 eV) and to L-state of the conduction band of a nanoisland (0.81 eV) fit the experimental data with a rather good accuracy. 相似文献