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1.
Zr3FeH5.3 exhibits hydrogen-induced magnetism below an ordering temperatureT 0=135 K. Comparison of three fit models for analysis of the zero field Mössbauer spectra belowT 0 is presented. The models are based on discrete and distributed static hyperfine fields and magnetic relaxation. The response of Zr3FeH5.3 to an applied field of 6.9 T indicates that antiferromagnetic interactions are present with spin canting also possible. 相似文献
2.
J. Balogh L. Bottyán I. Dézsi K. Papp F. Aubertin S. M. Fries U. Gonser 《Hyperfine Interactions》1986,28(1-4):803-806
Hydrogen desorption during heat treatments of (crystalline) Zr3FeH5.5 was studied by Mössbauer spectroscopy (MS), X-ray (powder) diffraction (XRD) and thermal gravimetry (TG). In case of sufficiently slow heating rate all hydrogen effuses below 650°K and no phase segregation occurs. At higher temperatures retained hydrogen induce phase separation into Fe2Zr (or more likely Fe2ZrHx) and zirconium hydride. The existence of a highly disordered f.c. tetragonal ternary hydride phase was also detected both by XRD (ao=4.76 Å, c=4.96 Å) and MS
. 相似文献
3.
The electronic structure and optical properties of the complex hydrides Ca2FeH6, Ca2RuH6, Mg2FeH6, Mg2RuH6, Sr2FeH6, Sr2RuH6 and Sr2OsH6 were studied using first-principles calculations. Optical spectra of the hydrides were compared with those of SiN x , In2O3 and ZnO determined from theoretical calculations and measured experimentally. Based on an analysis of band structure, it is found that the electrical conductivity of the hydrides is expected to be poor. However, optical properties of the hydrides in the energy range 0–3 eV are found to be almost the same as those of SiN x , In2O3, ZnO and TiO2. Hydrides are suggested to be used as antireflection layers and for passivation of surface and bulk defects. This finding could be useful for electronic device technology including solar cells. 相似文献
4.
H. Hagemann V. D'Anna S. Gomes G. Renaudin K. Yvon 《Journal of Physics and Chemistry of Solids》2011,72(4):286-289
The structural and vibrational properties of the isostructural compounds Ca2FeH6 and Sr2RuH6 are determined by periodic DFT calculations and compared with their previously published experimental crystal structures as well as new experimental vibrational data. The analysis of the vibrational data is extended to the whole series of alkaline-earth iron and ruthenium hydrides A2TH6 (A=Mg, Ca, Sr; T=Fe, Ru) in order to identify correlations between selected frequencies and the T-H bond length. The bulk moduli of Ca2FeH6 and Sr2RuH6 have also been determined within DFT. Their calculated values prove to compare well with the experimental values reported for Mg2FeH6 and several other compounds of this structure. 相似文献
5.
H. L. Zhou Y. Yu H. F. Zhang T. Gao 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,79(3):283-288
Mg2FeH6, which has one of the highest hydrogen storage capacities among Mg based 3d-transitional metal hydrides, is considered as an attractive material for hydrogen storage. Within density-functional perturbation theory (DFPT), we have investigated the structural, vibrational and thermodynamic properties of Mg2FeH6. The band structure calculation shows that this compound is a semiconductor with a direct X-X energy gap of 1.96 eV. The calculated phonon frequencies for the Raman-active and the infrared-active modes are assigned. The phonon dispersion curves together with the corresponding phonon density of states and longitudinal-transverse optical (LO-TO) splitting are also calculated. Findings are also presented for the temperature-dependent behaviors of some thermodynamic properties such as free energy, internal energy, entropy and heat capacity within the quasi-harmonic approximation based on the calculated phonon density of states. 相似文献
6.
The cubic intermetallic compound Hf2Fe can absorb large quantities of hydrogen gas without changing its crystal structure (Ti2Ni type). Whereas the Fe atoms do not have a moment in Hf2Fe we measured a moment of about 0.9 uB per Fe atom in the hydride Hf2FeH3. The ferromagnetic Curie temperature of Hf2FeH3 is Tc = 73 K. Using 57Fe Mössbauer effect spectroscopy we found that the isomer shift changes +0.40 mms?1 upon H2 take-up. This isomer shift change is not compatible with an explanation of the observed moment increase in terms of charge transfer from Fe to H. 相似文献
7.
利用X射线衍射技术、差示扫描量热分析技术和透射电子显微镜研究了非晶态Cu56Zr44合金的结构及其等温退火条件下的晶化过程.实验结果表明,非晶态Cu56Zr44合金在室温下的短程结构类似于硬球无规密堆积分布.在703K过冷液相区内等温退火时发现,当退火时间为3min时,晶化产物主要为Cu8Zr3相;当退火时间为6min时,Cu8Zr3关键词:
非晶态
56Zr44合金')" href="#">Cu56Zr44合金
结构
等温退火 相似文献
8.
Takahiro Matsuoka Naohisa Hirao Yasuo Ohishi Katsuya Shimizu Akihiko Machida Katsutoshi Aoki 《高压研究》2013,33(1):64-67
We present the first successful in situ simultaneous measurement of the electrical resistance and X-ray diffraction of FeH x (x~ 1) under high-pressure H2 up to 25.5 GPa and low temperatures down to 9 K. The electrical resistivity ρ showed a sharp increase with the formation of iron-hydride FeH x (x~ 1) at 3.5 GPa. The ?′-phase of FeH x was found to be metallic up to 25.5 GPa. The ρ vs. T curves up to 16.5 GPa approximately follow Fermi-liquid law below 25 K. However, T 5 was found to be better fitting at 25.5 GPa. This change can be considered to be related to the previously reported ferromagnetism collapse at corresponding pressure. 相似文献
9.
O.Yu. Khyzhun V.L. Bekenev M.V. Karpets I.Yu. Zavaliy 《Journal of Physics and Chemistry of Solids》2012,73(11):1302-1308
Electronic properties of Zr3V3O oxide, a very promising hydrogen-storage material, were studied both from theoretical and experimental points of view employing the full potential linearized augmented plane wave (FP-LAPW) method as well as X-ray photoelectron spectroscopy (XPS) and X-ray emission spectroscopy (XES). Total and partial densities of states of the constituting atoms of Zr3V3O have been derived from the FP-LAPW calculations. These data indicate that, the O 2p-like states are the dominant contributors in the bottom of the valence band, whilst the top of the valence band and the bottom of the conduction band of Zr3V3O are dominated by contributions of the V2 3d-like states, with slightly smaller contributions of the V1 3d-like states as well. Significant contributions of the Zr 4d-like states throughout the whole valence-band region and near the bottom of the conduction band are also characteristic of the electronic structure of Zr3V3O. The XPS valence-band spectra and the XES Zr Lβ2,15, V Lα and O Kα bands have been derived and compared on a common energy scale for Zr3V3O and Zr3V3O0.6 oxides. This comparison of the experimental spectra was found to be in excellent agreement with the results of the FP-LAPW calculations. In addition, the XPS Zr 3d, V 2p and O 1s core-level binding energies have been measured for Zr3V3O and Zr3V3O0.6 oxides. 相似文献
10.
This paper reports on the results of theoretical investigations carried out for the hydrides Mg2FeH6 and Mg2CoH5 and the mixed hydride Mg2(FeH6)0.5(CoH5)0.5 in terms of the full-potential linearized augmented plane wave (FLAPW) method. It has been shown that the partial substitution of the Co atoms for the Fe atoms leads to a slight increase in the stability of the hydride, but, at the same time, makes it impossible to increase the stability of the alloy. The high stability of the hydrides under investigation has been explained by the strong bonding between atoms of the transition metal and hydrogen. 相似文献
11.
使用配有团簇产生和化学反应源的飞行时间质谱装置,研究了锆氧阴离子团簇ZrxOy-与乙烷和丁烷的反应. 在反应中发现了Zr2O5H-和Zr3O7H-产物. 用密度泛函理论研究了乙烷在Zr2O5-上的反应通道,发现乙烷脱氢反应可以发生,从而证明观察到的产物是源于脱氢反应. 该工作揭示了锆氧负离子团簇与烷烃反应中的新通道. 相似文献
12.
It is shown that the chemical short-range order (CSRO) of amorphous Zr3Fe studied by Mössbauer spectroscopy is similar to the CSRO of metastable crystalline Zr3Fe formed during crystallization while it is quite different from the CSRO of the stable crystalline compounds (ZrFe2, Zr2Fe and orthorhombic Zr3Fe). 相似文献
13.
Owing to its outstanding electronic properties, black phosphorus (BP) is considered as a promising material for next-generation optoelectronic devices. In this work, devices based on BP/MXene (Zrn+1C n T2, T = O, F, OH, n = 1, 2) van der Waals (vdW) heterostructures are designed via first-principles calculations. Zrn+1C n T2 compositions with appropriate work functions lead to the formation of Ohmic contact with BP in the vertical direction. Low Schottky barriers are found along the lateral direction in BP/Zr2CF2, BP/Zr2CO2H2, BP/Zr3C2F2, and BP/Zr3C2O2H2 bilayers, and BP/Zr3C2O2 even exhibits Ohmic contact behavior. BP/Zr2CO2 is a semiconducting heterostructure with type-II band alignment, which facilitates the separation of electron-hole pairs. The band structure of BP/Zr2CO2 can be effectively tuned via a perpendicular electric field, and BP is predicted to undergo a transition from donor to acceptor at a 0.4 V/Å electric field. The versatile electronic properties of the BP/MXene heterostructures examined in this work highlight their promising potential for applications in electronics. 相似文献
14.
The structural, phase stabilities, mechanical, electronic and thermodynamic properties of intermetallic phases in Zr–Sn system are investigated by using first-principles method. The equilibrium lattice constants, enthalpy of formation (ΔHform) and elastic constants are obtained and compared with available experimental and theoretical data. The configuration of Zr4Sn is measured with reasonable precision. The ΔHform of five hypothetical structures are obtained in order to find possible metastable phase for Zr–Sn system. The mechanical properties, including bulk modulus, shear modulus, Young's modulus and Poisson's ratio, are calculated by Voigt–Reuss–Hill approximation and the Zr5Sn4 and Zr5Sn3 show excellent mechanical properties. The electronic density of states for Zr5Sn4, Zr5Sn3 and cP8-Zr3Sn are calculated to further investigate the stability of intermetallic compounds. Through the quasi-harmonic Debye model, the Debye temperature, heat capacity and thermal expansion coefficient under temperature of 0–300 K and pressure of 0–50 GPa for Zr5Sn3 and Zr5Sn4 are deeply investigated. 相似文献
15.
16.
The57Fe isomer shifts in the crystalline compounds Zr2Fe and Zr3Fe are calculated. We use the standard first-principles linear-muffin-tin-orbital formalism in the atomic sphere approximation (LMTO-ASA) to obtain the electronic structure of the compounds. The electronic structure of pure Fe was also calculated with the same formalism, where the local spin density approximation for the exchange correlation term is used. We found that the calculated isomer shift values are in good agreement with the experimental values for Zr2Fe and Zr3Fe found in the literature. 相似文献
17.
V.V. Nemoshkalenko V.P. Krivitskii A.P. Shpak L.I. Nikolajev 《Solid State Communications》1974,15(1):9-11
The intensity distribution of the Kβ-and L2,3-emission bands of pure silicon and silicon in ZrSi2, Zr3Si2, Zr5Si3 and Zr3Si are investigated. Some of the aspects of the electronic structure of these compounds are discussed. 相似文献
18.
The sintering behavior of Na3Zr2Si2PO12, Na3.08Zr1.96X0.04Si2PO12 (X = Mg, Ca, Sr, Ba), Na3Zr1.5 Si2PO12, and Na3Zr1.3Si2PO12 was studied between 900 and 1300°C. Microstructural examination indicated that liquid-phase sintering had occurred and that free ZrO2 was present in all of the samples. X-ray diffraction indicated that the NASICON and ZrO2 were monoclinic and that doping the Na3Zr2Si2PO12 with 0.02 mole% alkaline-earth ions (compared to the ZrO2 content) did not significantly increase the unit-cell volume. 相似文献
19.
20.
Multi-color long lasting phosphorescent (LLP) phenomenon in β-Zn3(PO4)2:Mn2+,Zr4+ was systematically investigated. It is found that the red (λEm=616 nm) LLP performance of Mn2+ such as brightness and duration is largely improved, and that the blue (λEm=475 nm) LLP of Zr4+ with lower intensity appears when Zr4+ ions are co-doped into the matrix. The fluorescence, phosphorescence and thermoluminescence (TL) spectra show that Mn2+ ion is solely expected as a luminescent center, while Zr4+ ion not only acts as a luminescent center, but also induces an electron trap (TrapZr) associated with a TL peak at 344 K. The trap depth for TrapZr is 0.25 eV, while that for the intrinsic trap is 0.38 eV, associated with a dominant peak at 385 K for Zn3(PO4)2:Mn2+. The Zr4+-induced trap with suitable depth is responsible for the improvement of the red LLP of Mn2+ ion and the appearance of the blue LLP of Zr4+ ion. The LLP mechanism is also investigated. 相似文献