Der Chemische Transport von Mischkristallen im System NiO/ZnO

Chemical Vapor Transport of Solid Solutions. 2 Chemical Transport of NiO/ZnO‐Mixed Crystals By means of chemical vapor transport using HCl as transport agent (900 → 750 °C) it is possible to prepare ZnO‐rich and NiO‐rich mixed crystals in the system Zn/Ni/O. The mixed‐crystals are homogeneous. Thermodynamic calculations allow to understand the experiments.     

Der Chemische Transport von Mischkristallen in den Systemen MnS/ZnS,FeS/ZnS und FeS/MnS

Chemical Vapor Transport of Solid Solutions. 5 Chemical Transport of MnS/ZnS, FeS/ZnS, and FeS/MnS Mixed Crystals By means of chemical vapor transport it is possible to prepare in the quasibinary systems MnS/ZnS, FeS/ZnS, and FeS/MnS the mixed crystals (Mn,Zn)S (sphalerite- and wurtzite-type), (Fe,Zn)S (sphalerite- and wurtzite-type), (Fe,Mn)S (NaCl-type), MnS(ZnS) (NaCl-type), FeS(ZnS) and FeS(MnS) (both NiAs-type) in form of single crystals. The experiments harmonize with the phase diagrams. Lattice parameters have been determined.     

Chemischer Transport fester Lösungen. 9 [1] Zum Chemischen Transport fester Lösungen in den Systemen Eisen(II)/Cobalt(II)‐ und Mangan(II)/Cobalt(II)‐germanat

Metagerma‐Chemical Vapor Transport of Solid Solutions. 9. The Chemical Vapor Transport of Solid Solutions in the System Iron(II)/(Cobalt(II)‐and Manganese(II)/Cobalt(II) Germanate By means of chemical vapor transport methods (900 → 700 °C) using HCl as transport agent FeGeO₃, Fe₂GeO₄ and MnGeO₃ have been prepared. Co₂GeO₄ and Fe₂GeO₄ as well as CoGeO₃ and FeGeO₃ form continuous crystalline solid solutions, whereas in MnO/CoO/GeO₂ two different phases (Mn_xCo_1‐x)GeO₃ are formed. All of these systems show congruent transport behaviour. Chemical vapor transport has been proved a suitable method to prepare solid solutions.     

Chemischer Transport intermetallischer Phasen. 2 [1]. Der chemische Transport von Mischkristallen im System Co/Ni

Chemical Vapor Transport of Intermetallic Systems. 2. Chemical Transport of Co/Ni-mixed Crystals By means of chemical transport reaction it is possible to prepare Co/Ni-mixed crystals in a wide range of percentage composition between 5 and 75 weight % Nickel. This is possible using a 3-zone-oven. Thermodynamic considerations allow to understand the experiments.     

Chemischer Transport intermetallischer Phasen. 3 [1]. Der chemische Transport von Mischkristallen im System Mo/W

Chemical Vapor Transport of Intermetallic Systems. 3. Chemical Transport of Mo/W-mixed Crystals Mo/W-mixed crystals can be prepared by means of chemical vapor transport with HgBr₂ (1000°C→900°C). It is known [2] that the transport reaction of tungsten begins hours or even days after starting the experiment. This is the reason for the unusual composition of deposited crystals: EDX-analysis show them to have a Mo-rich nucleus and a W-rich shell.     

Der Chemische Transport von Mischkristallen im System CoO/NiO

Chemical Vapor Transport of Solid Solutions. 1 Chemical Transport of CoO/NiO‐Mixed Crystals CVT‐methods are a suitable pathway to prepare single crystals of ionic mixed‐crystals with variable composition. This is shown in the case of CoO/NiO‐mixed crystals. The composition of the product is mainly determined by the composition of the starting material. Homogeneous single crystals of a well defined composition can be prepared in a foreseeable manner. The experiments can be understood by thermochemical calculations.     

Chemischer Transport fester Lösungen. 20 [1] Der Chemische Transport von Mischphasen in den Systemen CdS/CdTe und CdSe/CdTe

Chemical Vapor Transport of Solid Solutions. 20, Chemical Vapor Transport of Mixed Phases in the Systems CdS/CdTe and CdSe/CdTe By means of CVT methods using iodine as transport agent (900 → 800 °C) in the systems CdS/CdTe and CdSe/CdTe mixed crystals could be prepared. The system CdS/CdTe shows a broad miscibility gap. Sulfur rich mixed crystals as well as tellurium rich ones could be prepared. The system CdSe/CdTe shows complete miscibility for all Se/Te ratios. In both systems congruent transport has been observed.     

Chemischer Transport intermetallischer Phasen Der chemische Transport von Mischkristallen im System Cu/Ag

Chemical Vapor Transport of Intermetallic Systems Chemical Transport of Cu/Ag-mixed Crystals By means of chemical transport reaction it is possible to prepare Cu-rich and Ag-rich mixed crystals in the Cu/Ag system. The composition of individual deposited crystals was different. Mass-spectrometric analysis of the gas-phase above CuI/AgI has shown the formation of CuAg₂I_3,g und Cu₂AgI_3,g. Thermodynamic computations explain the formation of crystals as well as the reaction conditions.     

Chemischer Transport fester Lösungen. 24 [1] Bildung von Mischphasen und chemischer Transport im System MnO/MnS

Chemical Vapor Transport of Solid Solutions. 24. [1] Formation and Chemical Vapor Transport of MnO/MnS mixed Crystals In the System MnO/MnS mixed crystals MnS_1?xO_x (x = 0 …0,04) are formend. By means of CVT methods using bromine as transport agent (1000 → 900 °C) MnO, MnS and MnS:O‐mixed phases could be obtained. The role of traces of water is discussed.     

Chemischer Transport fester Lösungen. 27. Mischphasenbildung und chemischer Transport im System ZnSe/GaAs

Chemical Vapor Transport of Solid Solutions. 27. Formation of Solid Solutions and Chemical Vapor Transport in the System GaAs/ZnSe The miscibility of ZnSe and GaAs as a function of temperature has been investigated. At temperatures above 1100 °C GaAs and ZnSe form out a continous crystalline solid solution. The phase diagram of this system is presented. Mixed crystals in the system GaAs/ZnSe can be prepared by means of chemical vapor transport using iodine as transport agent. Mass spectrometric investigations have shown the formation of AsSeI(g), an up to now unknown triatomic molecule. First approximate thermodynamic Data for AsSeI(g) are given. The knowledge of AsSeI and its thermodynamic stability is necessary to understand the transport phenomena.     

Der Chemische Transport ternärer intermetallischer Phasen in den Systemen Cr/Co/Ge und Co/Ta/Ge

Chemical Vapor Transport of Intermetallic Systems. 11 Chemical Vapor Transport of Ternary Intermetallic Phases in the Systems Cr/Co/Ge and Co/Ta/Ge By means of chemical vapor transport using iodine as transport agent it is possible to prepare a number of ternary intermetallic compounds in the system Co/Cr/Ge as single crystals. The transport behaviour in this ternary system is related to that in the binary systems. Some informations are given about transport phenomena in the systems Co/Cr and Co/Ta/Ge.     

Der Chemische Transport von Mischkristallen im System FeS/MnS/ZnS

Chemical Vapor Transport of Solid Solutions. 7. Chemical Vapor Transport of FeS/MnS/ZnS Mixed Crystals By means of chemical vapor transport using iodine as transport agent (900 → 800 °C) it is possible to prepare in the quasiternary system FeS/MnS/ZnS the mixed crystals (Fe,Mn,Zn)S (sphalerite and wurtzite type), (Fe,Mn)S(ZnS) (NaCl type) and FeS(MnS,ZnS) (NiAs type) in form of single crystals. Based on the composition of these phases the phase diagram for the system FeS/MnS/ZnS at 800 °C was drawn up. The incongruent transport process leads to the accumulation of ZnS in the crystallization zone.     

Chemischer Transport fester Lösungen. 22 [1] Beschreibung des Chemischen Transports im System ZnS/ZnSe

Studies on the Chemical Vapor Transport in the System ZnS/ZnSe By means of chemical transport reactions homogeneous ionic mixed crystals with well defined compositions can be prepared in a simple way. This is shown at the example of ZnS/ZnSe‐mixed crystals. ZnS_1?xSe_x‐mixed crystals can be prepared by chemical vapour transport in the temperature gradient 1000 → 900 °C using iodine as transport agent. A thermodynamic model is presented to calculate the thermodynamic stability of ionic mixed phases and possible enrichment effects during the vapor transport. The results are compared with experimental fundings and well known transport models.     

Study of formation and thermal stability of the Fe/ZnO(000‐1) interface

Formation and thermal stability of the Fe/ZnO(000‐1) interface have been studied by means of X‐ray photoelectron spectroscopy and low energy electron diffraction. The results indicated a pseudo 2D growth mode for iron on ZnO. In addition, it could be shown that under ultra high vacuum conditions deposited Fe⁰ on a ZnO(000‐1) single crystal was partially oxidized by a small fraction of residual ? OH‐groups and ZnO to FeO. A strong temperature dependence of the interface reactivity was found upon annealing at temperatures up to 600 °C. Starting from 200 °C iron was first oxidized to bivalent iron oxide. After complete oxidation of Fe⁰ to Fe²⁺ at 375 °C, Fe²⁺ reacted to Fe³⁺. Above temperatures of 500 °C the deposited metallic iron was completely oxidized to trivalent iron. Further experiments with FeO on ZnO showed the oxidation state and the oxide film thickness of the deposited iron to be mainly dependent on the annealing temperature. Copyright © 2008 John Wiley & Sons, Ltd.     

Electrical,optical and photocatalytic properties of Ti-loaded ZnO/ZnO and Ti-loaded ZnO nanospheres

Ti-loaded ZnO and Ti-loaded ZnO/ZnO nanoparticles have been synthesized by sol–gel method and analyzed for photocatalyst application. The phase confirmation was analyzed by powder XRD and surface morphology with HR-SEM and EDAX spectrum. The particle size measured using HR-TEM and SAED pattern confirms the crystalline nature of Ti-loaded ZnO and Ti-loaded ZnO/ZnO nanoparticles. The optical properties were studied with UV–visible diffuse reflectance spectra. The DRS of Ti-loaded ZnO/ZnO nanoparticles are similar to those of pristine ZnO nanoparticles. The KM plots show both the synthesized Ti-loaded ZnO/ZnO and Ti-loaded ZnO exhibit in UV-A region. The electric properties are studied with impedance analyzer, and the results show the charge-transfer resistance of Ti-loaded ZnO/ZnO is larger than that of Ti-loaded ZnO nanoparticles. The photocatalytic activity was studied with methylene blue dye and phenol degradation by Ti-loaded ZnO/ZnO, Ti-loaded ZnO, TiO₂ and ZnO nanoparticles. The photocatalytic activity of Ti-loaded ZnO/ZnO nanospheres is slightly higher than that of other nanoparticles, which shows that they have excellent application as photocatalyst.     

Zur Kenntnis der Systeme Li2O/CoO und Li2O/ZnO

On the Systems Li₂O/CoO and Li₂O/ZnO According to powder photographs the systems Li₂O/CoO and Li₂O/ZnO are so far similar as the Li-richest phase in near ?Li₄MO₃”?. Single crystal investigations lead to a pseudocubic, trigonal unit cell; a = 13.14, c = 7.99 Å (Zn); a = 13.10, c = 7.98 Å (Co). The oxygen form a cubic closest packing. Surprisingly there is obviously no completely ordered arrangement of cations. In spite of single crystal data the extent of the phases is still unknown.     

Chemischer Transport und Sauerstoffionenleitfähigkeit von Mischkristallen im System In2O3/SnO2

Chemical Transport of Solid Solutions. 8. Transport Phenomena and Ionic Conductivity in the In₂O₃/SnO₂ System Chemical transport reactions are a suitable pathway to the preparation of In₂O₃‐rich and SnO₂‐rich mixed crystals coexisting in the In₂O₃/SnO₂ system (Cl₂ as transport agent, 1050 → 900 °C). Experiments are consistent with thermodynamic calculations. The existence of other phases in the system In₂O₃/SnO₂ could not be confirmed. The ionic conductivity of In₂O₃(SnO₂) was investigated.     

化学气相输运法(CVT)制备微米级的喇叭管状ZnO晶体

氧化锌为直接带隙宽禁带半导体材料,由于其优良的光电性能,预计在未来光电信息领域有着巨大的应用前景,引起了广泛的研究兴趣.     

A systematic study of neutral and charged 3d-metal trioxides and tetraoxides

Using density functional theory with generalized gradient approximation, we have performed a systematic study of the structure and properties of neutral and charged trioxides (MO(3)) and tetraoxides (MO(4)) of the 3d-metal atoms. The results of our calculations revealed a number of interesting features when moving along the 3d-metal series. (1) Geometrical configurations of the lowest total energy states of neutral and charged trioxides and tetraoxides are composed of oxo and∕or peroxo groups, except for CuO(3)(-) and ZnO(3)(-) which possess a superoxo group, CuO(4)(+) and ZnO(4)(+) which possess two superoxo groups, and CuO(3)(+), ZnO(3)(+), and ZnO(4)(-) which possess an ozonide group. While peroxo groups are found in the early and late transition metals, all oxygen atoms bind chemically to the metal atom in the middle of the series. (2) Attachment or detachment of an electron to∕from an oxide often leads to a change in the geometry. In some cases, two dissociatively attached oxygen atoms combine and form a peroxo group or a peroxo group transforms into a superoxo group and vice versa. (3) The adiabatic electron affinity of as many as two trioxides (VO(3) and CoO(3)) and four tetraoxides (TiO(4), CrO(4), MnO(4), and FeO(4)) are larger than the electron affinity of halogen atoms. All these oxides are hence superhalogens although only VO(3) and MnO(4) satisfy the general superhalogen formula.     

低化学稳定性复杂组分含磷铝硅酸盐玻璃体结构——含磷铝硅酸盐玻璃体结构模型与肥料开发

基于玻璃体无规则网络学说,建立了包含P2O5,K2O,CaO,MgO,SiO2,Fe2O3,FeO,Al2O3,B2O3,MnO,CuO,ZnO,NiO,MoO2,CoO和TiO2低化学稳定性复杂组分的玻璃体结构模型,推导出扩展的玻璃结构因子(Ob/Yb)ex及其计算式.对高效利用低品位磷矿、磷矿选矿尾矿、难溶性钾矿和低品位磷钾矿制造能为农作物吸收的玻璃体肥料具有一定的理论意义和应用价值.