Magnetic Properties of Sputtered Fe-O and Co-O Thin Films

1995 ◽  
Vol 403 ◽  
Author(s):  
D. V. Dimitrov ◽  
A. S. Murthy ◽  
G. C. Hadjipanayis ◽  
C. P. SWANN
Keyword(s):  
Grain Size ◽  
Low Temperatures ◽  
Room Temperature ◽  
Oxide Films ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Large Shift ◽  
X Ray ◽  
Grain Size And Shape ◽  
Spherical Grains

AbstractFe-O and Co-O films were prepared by DC magnetron sputtering in a mixture of Ar and O2 gases. By varying the oxygen to argon ratio, oxide films with stoichiometry FeO, Fe3O4, α-Fe2O3, CoO and Co3O4 were produced. TEM studies showed that the Fe – oxide films were polycrystalline consisting of small almost spherical grains, about 10 nm in size. Co-O films had different microstructure with grain size and shape dependent on the amount of oxygen. X-ray diffraction studies showed that the grains in Fe-O films were randomly oriented in contrast to Co-O films in which a <111> texture was observed. Pure FeO and α-Fe2O3 films were found to be superparamagnetic at room temperature but strongly ferromagnetic at low temperatures in contrast to the antiferromagnetic nature of bulk samples. A very large shift in the hysteresis loop, about 3800 Oe, was observed in field cooled Co-CoO films indicating the presence of a large unidirectional exchange anisotropy.

scholarly journals An operando X-ray diffraction study of chloroaluminate anion-graphite intercalation in aluminum batteries

2018 ◽  
Vol 115 (22) ◽  
pp. 5670-5675 ◽  
Author(s):  
Chun-Jern Pan ◽  
Chunze Yuan ◽  
Guanzhou Zhu ◽  
Qian Zhang ◽  
Chen-Jui Huang ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Room Temperature ◽  
Negative Electrode ◽  
Discharge Voltage ◽  
Battery Life ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stage 4 ◽  
Graphite Intercalation ◽  
Battery Discharge

We investigated rechargeable aluminum (Al) batteries composed of an Al negative electrode, a graphite positive electrode, and an ionic liquid (IL) electrolyte at temperatures down to −40 °C. The reversible battery discharge capacity at low temperatures could be superior to that at room temperature. In situ/operando electrochemical and synchrotron X-ray diffraction experiments combined with theoretical modeling revealed stable AlCl4−/graphite intercalation up to stage 3 at low temperatures, whereas intercalation was reversible up to stage 4 at room temperature (RT). The higher-degree anion/graphite intercalation at low temperatures affords rechargeable Al battery with higher discharge voltage (up to 2.5 V, a record for Al battery) and energy density. A remarkable cycle life of >20,000 cycles at a rate of 6C (10 minutes charge time) was achievable for Al battery operating at low temperatures, corresponding to a >50-year battery life if charged/discharged once daily.

Effect of titanium addition on a Ni-Al-Co alloy

1990 ◽  
Vol 48 (4) ◽  
pp. 938-939
Author(s):  
L. S. Lin ◽  
G. W. Levan ◽  
S. M. Russell ◽  
C. C. Law
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Room Temperature ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
Titanium Addition ◽  
X Ray ◽  
Gamma Prime ◽  
Room Temperature Ductility ◽  
Ti Addition

AEM examinations of a NiAlCo alloy of composition Ni-29 at.% Al-21 at.% Co after room temperature compression show that the microstructure consists of a twinned tetragonal matrix (L10, marked A in Figure 1a) and ordered fcc gamma prime precipitates (L12, marked B in Figure 1a) along grain boundaries. The compressive yield strengths of this alloy at room temperature and 760°C are 754 MPa and 163 MPa respectively. It also has superior room temperature ductility as compared to binary NiAl. An addition of 5 at.% Ti at the expense of Ni was made to this alloy in order to increase the yield strengths. The quarternary alloy shows compressive yield strengths of 976 MPa and 403 MPa at room temperature and 760°C, respectively, indicating that the Ti addition is having the desired effect.Comparison of the microstructures of the two alloys after room temperature compression (Figures la and lb) shows that the Ti containing alloy has a smaller grain size. X-ray diffraction data indicate that the gamma prime volume fraction increases from 10% to 20% as the result of the Ti addition. Titanium was also found to stabilize the B2 matrix (marked A in Figure lb) as no tetragonal L10 phase was found. All precipitates along grain boundaries were identified by micro-diffraction to be gamma prime.

Fabrication of Mg2Si Thermoelectric Materials by Mechanical Alloying and Spark-Plasma Sintering Process

2006 ◽  
Vol 6 (11) ◽  
pp. 3429-3432
Author(s):  
Chung-Hyo Lee ◽  
Seong-Hee Lee ◽  
Sung-Yong Chun ◽  
Sang-Jin Lee
Keyword(s):  
Grain Size ◽  
Mechanical Alloying ◽  
Spark Plasma Sintering ◽  
Room Temperature ◽  
Atomic Ratio ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma

A mixture of pure Mg and Si powders with an atomic ratio 2:1 has been subjected to mechanical alloying (MA) at room temperature to prepare the Mg2Si thermoelectric material. Mg2Si intermetallic compound with a grain size of 50 nm can be obtained by MA of Mg66.7Si33.3 powders for 60 hours and subsequently annealed at 620 °C. Consolidation of the MA powders was performed in a spark plasma sintering (SPS) machine using graphite dies up to 800–900 °C under 50 MPa. The shrinkage of consolidated samples during SPS was significant at about 250 °C and 620 °C. X-ray diffraction data shows that the SPS compact from 60 h MA powders consolidated up to 800 °C consists of only nanocrystalline Mg2Si compound with a grain size of 100 nm.

Phase Formation and Grain Growth of BSCZT Ceramics Prepared by BST-BZT Seed Induced Method

2018 ◽  
Vol 766 ◽  
pp. 175-179
Author(s):  
Jiraporn Dangsak ◽  
Sukum Eitssayeam ◽  
Denis Russell Sweatman ◽  
Uraiwan Intatha
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Phase Formation ◽  
Room Temperature ◽  
Single Phase ◽  
Seed Crystal ◽  
Lead Free ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Values

In this work, lead-free Ba0.4Sr0.4Ca0.2Zr0.05Ti0.95O3 ceramics were prepared by the seed induced method using (0.5Ba0.6Sr0.4TiO3–0.5BaZr0.05Ti0.95O3) (BST-BZT) seed. Seed crystals with concentrations of 0, 2.5, 5, 7.5, 10 mol% were mixed with BSCZT powder for 24 h and sintered at 1400 °C for 4 h. The phase formation and microstructure of BSCZT ceramic were characterized by X-ray diffraction technique (XRD) and the scanning electron microscopy (SEM). All samples showed a single phase perovskite structure without impurities and exhibited the existence of the tetragonal phase. The density values of the ceramics decreased from 4.90 to 4.75 g/cm3 with increasing seed crystal concentrations. The grain size of the sample without seed was 3.71 μm, whereas a grain size of 8.99 μm was observed for the sample with 10 mol% seed crystal. The dielectric constant at room temperature at 1 kHz was 1831 for the sample with 10 mol% seed crystal while the dielectric constant of the sample without seed was 1484. From the results in this work, BST-BZT seed can increase grain size and improve the dielectric constant at room temperature.

Transparent Conducting TGZO Thin Films Deposited by DC Magnetron Sputtering at Room Temperature

2010 ◽  
Vol 663-665 ◽  
pp. 1041-1044
Author(s):  
Han Fa Liu ◽  
Hua Fu Zhang
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Room Temperature ◽  
Hexagonal Structure ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
X Ray ◽  
Transparent Conducting ◽  
Average Transmittance ◽  
Co Doped

Transparent conducting Ti-Ga co-doped zinc oxide (TGZO) thin films with high transmittance, low resistivity were firstly prepared on glass substrate by direct current (DC) magnetron sputtering at room temperature. X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that the TGZO films are polycrystalline with a hexagonal structure and have a preferred orientation along the c-axis perpendicular to the substrate. The lowest resistivity obtained in our experiment is 3.95×10-4Ω⋅cm. The average transmittance of the films is over 92% in the range of 400~760 nm.

Deposition of Photoluminescent Nanocrystalline Silicon Films by SiF4-SiH4-H2 Plasmas

1996 ◽  
Vol 452 ◽  
Author(s):  
G. Cicala ◽  
G. Bruno ◽  
P. Capezzuto ◽  
L. Schiavulli ◽  
V. Capozzi ◽  
...  
Keyword(s):  
Grain Size ◽  
Porous Silicon ◽  
Vapor Deposition ◽  
Room Temperature ◽  
Energy Gap ◽  
Chemical Vapor ◽  
Nanocrystalline Silicon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Grain Size

AbstractVisible photoluminescence at 1.62 eV has been observed at room temperature from fluorinated and hydrogenated nanocrystalline silicon (nc-Si:H,F) produced in a typical plasma enhanced chemical vapor deposition system. The use of SiF4-SiH4-H2 mixture, because of the H2 dilution and the presence of SiF4, favours the amorphous - crystalline transition through the etching process of the amorphous phase. The x - ray diffraction measurements give an average grain size of about 100 Å. The presence of these nanocrystals shifts the absorption edge of the films towards higher energy. An energy gap of 2.12 eV is estimated, although the hydrogen content in the material is only 4.5 at. %. The temperature dependence of the photoluminescence behaves similarly to that of porous silicon.

scholarly journals Ni-Mn-Ga films in the austenite and the martensite structures at room temperature: Uniaxial texturation and epitaxial growth

2009 ◽  
Vol 1200 ◽  
Author(s):  
Jérémy Tillier ◽  
Antinéa Einig ◽  
Daniel Bourgault ◽  
Philippe Odier ◽  
Luc Ortega ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Vacuum Annealing ◽  
Sacrificial Layer ◽  
Epitaxial Films ◽  
Fiber Texture ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
X Ray ◽  
Scanning Electron

AbstractNi-Mn-Ga films in the austenite and the martensite structures at room temperature have been obtained using the DC magnetron sputtering technique. Two elaboration processes were studied. A first batch of samples was deposited using a resist sacrificial layer in order to release the film from the substrate before vacuum annealing. This process leads to polycrystalline films with a strong (022) fiber texture. The martensitic phase transformation of such polycrystalline freestanding films has been studied by optical and scanning electron microscopy. A second batch of samples was grown epitaxially on (100)MgO substrates using different deposition temperatures. The texture has been analyzed with four-circle X-ray diffraction. Epitaxial films crystallized both in the austenite and the martensite structures at room temperature have been studied.

scholarly journals X-ray, IR and SEM studies on some Li-Cd ferrites

YMER Digital ◽  
2021 ◽  
Vol 20 (12) ◽  
pp. 333-340
Author(s):  
Sudhir Kulkarni ◽  
Keyword(s):  
Grain Size ◽  
Room Temperature ◽  
Single Phase ◽  
Lattice Parameter ◽  
Lithium Ferrite ◽  
Cadmium Content ◽  
X Ray Diffraction ◽  
Ceramic Method ◽  
X Ray ◽  
Single Phase Formation

Lithium-Cadmium ferrites with general formula Li0.5-x/2 Fe2.5-x/2 Cdx O4 (with x = 0,0.1,0.2....,0.7) were prepared by standard ceramic method. X-ray diffraction studies confirms single phase formation and lattice parameters were calculated. The crystal structure is cubic and lattice parameter increases with increasing Cd content. The infrared absorption (IR) spectra of all the samples were recorded in the range 200-800 cm-1 at room temperature in the KBr medium. Lithium ferrite shows four principal bands and some shoulders have been observed. The force constants Kt and Ko were calculated using Waldron's analysis. Scanning electron microscopy studies shows increase in grain size up to x = 0.1 and then the grain size decreases with increase in cadmium content.

Nano Aluminum Powders Oxidation in CO2 and O2 Environments

2013 ◽  
Vol 771 ◽  
pp. 113-117 ◽  
Author(s):  
Hong Bo Pei ◽  
Yang Liu ◽  
Hui Ren
Keyword(s):  
Low Temperatures ◽  
Room Temperature ◽  
Oxidation Process ◽  
Oxidation Products ◽  
X Ray Diffraction ◽  
Aluminum Particles ◽  
Aluminum Powders ◽  
X Ray ◽  
Oxidation Processes ◽  
Oxidation Properties

An experimental study of oxidation of nano aluminum (Al) powders in CO2 and O2 is described. The oxidation is studied using thermogravimetric (TG) measurements from room temperature to 1500°C. Partially oxidized samples are recovered and their compositions are analyzed using X-ray diffraction. The oxidation product morphology was examined using SEM. Dimensional properties of aluminum particles have a significant influence on the oxidation processes. The nano aluminum reaction onset temperature was much lower than micro aluminum. Distinctly different oxidation properties of nano aluminum powders were shown between CO2 and O2. nano aluminum powders could ignite in O2 at fairly low temperatures around 530 °C. However ignition for nano aluminum powders in CO2 didn't appeared below 1500 °C. There was a weight loss in the TG curves at around 1200 °C for nano Al-CO2 system. It was thought that small amount of carbon formed in the oxidation process. The XRD showed that both the nano aluminum oxidation products were α-Al2O3 in CO2 and O2.

X-Ray Diffraction Study of the Phase Transition of the ${\rm Si}(111)(\sqrt{3} \times \sqrt{3})\mbox{-Ag}$ Surface

2003 ◽  
Vol 10 (02n03) ◽  
pp. 519-524 ◽  
Author(s):  
Toshio Takahashi ◽  
Hiroo Tajiri ◽  
Kazushi Sumitani ◽  
Koichi Akimoto ◽  
Hiroshi Sugiyama ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Low Temperatures ◽  
Diffuse Scattering ◽  
Room Temperature ◽  
Bragg Reflection ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Displacive Phase Transition

The structure of the [Formula: see text] surface was studied at both room temperature and a low temperature of 50 K using grazing incidence X-ray diffraction. At low temperatures diffuse scattering was observed in addition to Bragg reflection. Least squares analyses for Bragg reflections using anisotropic Debye–Waller factors show that the structure at 50 K is consistent with an inequivalent triangle (IET) model, while the structure at room temperature is explained by a honeycomb-chained triangle (HCT) model with strong anisotropic Debye–Waller factors. From the temperature dependence of diffuse scattering, the phase transition temperature Tc and critical exponent β were determined to be about 150 K and 0.27. Some Bragg intensities showed discontinuous changes in their first derivatives at Tc. The results favor a displacive phase transition rather than an order–disorder one.

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