Physical Properties Of Single-Phase Skutterudite Thin-Films (CoSb3 and IrSb3)

1998 ◽  
Vol 545 ◽  
Author(s):  
J. C. Caylor ◽  
A. M. Stacy ◽  
T. Sands ◽  
R. Gronsky

AbstractBulk skutterudite phases based on the CoAs3 structure have yielded compositions with a high thermoelectric figure-of-merit (“ZT”) through the use of doping and substitutional alloying. It is postulated that further enhancements in ZT may be attained in artificially structured skutterudites by engineering the microstructure to enhance carrier mobility while suppressing the phonon component of the thermal conductivity. In this work the growth and properties of singlephase CoSb3 and IrSb3 skutterudite thin films are reported. The films are synthesized by pulsed laser deposition (PLD) where the crystallinity can be controlled by the deposition temperature. Powder X-ray diffraction (PXRD), Transmission electron microscopy (TEM) and Rutherford- Back Scattering (RBS) were used to probe phase, structure, morphology and stoichiometry of the films as functions of growth parameters and substrate type. A substrate temperature of 250°C was found to be optimal for the deposition of the skutterudites from stoichiometric targets. Above this temperature the film is depleted of antimony due to its high vapor pressure eventually reaching a composition where the skutterudite structure is no longer stable. However, when films are grown from antimony-rich targets the substrate temperature can be increased to at least 350°C while maintaining the skutterudite phase. In addition, adhesion properties of the films are explored in terms of the growth mode and substrate interaction. Finally, preliminary room temperature electrical and thermal measurements are reported.

1998 ◽  
Vol 526 ◽  
Author(s):  
J.C. Caylor ◽  
A.M. Stacy ◽  
P. Bandaru ◽  
T. Sands ◽  
R. Gronsky

AbstractRecent advances in doping and substitutional alloying of bulk skutterudite phases based on the CoAs3 structure have yielded compositions with high thermoelectric figures-of-merit (“ZT”). It is postulated that further enhancements in ZT may be attained in artificially-structured skutterudites by engineering the microstructure to enhance carrier mobility while suppressing the phonon component of the thermal conductivity. This work describes the growth of single-phase skutterudite thin films (CoSb3 and IrSb3) by pulsed laser deposition. A substrate temperature of 250°C has been found to be optimal for the deposition of the skutterudites from stoichiometric targets. Above this temperature, the film is depleted of antimony due to its high vapor pressure. However, when films are grown from antimony-rich targets, the substrate temperature can be increased to at least 350°C without losing the skutterudite phase. Films from both target types were characterized with X-ray diffraction and Rutherford-Back-Scattering (RBS) to reveal structure and stoichiometry. Some preliminary electrical measurements will also be shown.


2007 ◽  
Vol 14 (04) ◽  
pp. 755-759 ◽  
Author(s):  
D. U. LEE ◽  
J. H. JUNG ◽  
T. W. KIM ◽  
H. S. LEE ◽  
H. L. PARK ◽  
...  

CdTe thin films were grown on GaAs (100) substrates by using molecular beam epitaxy at various temperatures. The results of the X-ray diffraction (XRD) patterns showed that the orientation of the grown CdTe thin films was the (100) orientation. XRD patterns, atomic force microscopy images, high-resolution transmission electron microscopy (HRTEM) images, and photoluminescence spectra showed that the crystallinity of CdTe (100) epilayers grown on GaAs (100) substrates was improved by increasing the substrate temperature. HRTEM images showed that misfit dislocations existed at the CdTe / GaAs heterointerface. These results can help improve understanding of the substrate temperature effect on the structural and the optical properties of CdTe (100)/ GaAs (100) heterostructures.


1991 ◽  
Vol 243 ◽  
Author(s):  
K.Y. Kim ◽  
H.I. Hwang ◽  
J.Y. Lee ◽  
W.K. Choo

AbstractPbTiO3 thin films on Si (100) plane were prepared by the DC reactive multitarget cosputtering technique. The film composition and structure were examined as a function of deposition parameters. The crystal structure and microstructure of PbTiO3 thin film deposited on Si at low substrate temperature of 200°C were examined as a fuction of post-annealing temperature by X-ray diffraction and transmission electron microscopy.The ferroelectric domain configurations were analyzed by plane-view TEM. The preferred orientation of PbTiO3 thin films deposited on MgO (100) and sapphire (1102) at high substrate temperature of 520°C were also examined.


1993 ◽  
Vol 301 ◽  
Author(s):  
Susan Z. Hua ◽  
L. Salamanca-Riba ◽  
M. Wuttig ◽  
P. K. Soltani

ABSTRACTThe microstructure and its effects on the photoluminescence properties of SrS:Eu2+,Sm3+ thin films grown with different conditions were studied by transmission electron microscopy, x-ray diffraction and photoluminescence techniques. The SrS:Eu2+,Sm3+ thin films were prepared by e-beam evaporation at different substrate temperatures and growth rates. Both of these growth conditions affect the crystallinity of the thin films. The Sm3+ emission is stronger in the films grown at higher growth rates and at an optimum substrate temperature. We believe that the stronger Sm3+ emission is due to the higher population of Sm trivalent charge states in the films. Further increase of the substrate temperature increases the grain size in the films, but has no significant effect on the PL emission properties. In contrast, the Eu2+ emission is less sensitive to growth conditions.


1994 ◽  
Vol 341 ◽  
Author(s):  
R. M. Ribeiro ◽  
M. J. M. Gomes ◽  
E. De Matos Gomes ◽  
J. A. Ferreira ◽  
P. L. Q. Mantas ◽  
...  

AbstractPLZT thin films from a stoichiometric (9/65/35) commercial target were laser deposited using the second and third harmonics of a nanosecond Nd:YAG laser. The films were grown on oriented sapphire substrates and analysed by X-ray diffraction, SEM and EDX techniques. The influence of the deposition parameters laser fluence and substrate temperature on the physical characteristics of the films is presented.


1995 ◽  
Vol 385 ◽  
Author(s):  
M. Grant Norton ◽  
Wenbiao Jiang ◽  
J. Thomas Dickinson

ABSTRACTThin films of polytetrafluoroethylene have been formed by the pulsed-laser deposition technique. The structure of the films was found to be dependent upon the substrate temperature during deposition. At substrate temperatures from room temperature to 200°C the films were determined, by transmission electron microscopy and X-ray diffraction techniques, to be amorphous. Films formed at higher substrate temperatures were found to contain both amorphous and crystalline components. The data for the crystalline component is consistent with it being highly ordered with the long helical molecular chains aligned parallel to the film-substrate interface plane. The maximum amount of crystalline material occurred when the substrate temperature was close to the melting temperature of the polymer.


Author(s):  
J. T. Sizemore ◽  
D. G. Schlom ◽  
Z. J. Chen ◽  
J. N. Eckstein ◽  
I. Bozovic ◽  
...  

Investigators observe large critical currents for superconducting thin films deposited epitaxially on single crystal substrates. The orientation of these films is often characterized by specifying the unit cell axis that is perpendicular to the substrate. This omits specifying the orientation of the other unit cell axes and grain boundary angles between grains of the thin film. Misorientation between grains of YBa2Cu3O7−δ decreases the critical current, even in those films that are c axis oriented. We presume that these results are similar for bismuth based superconductors and report the epitaxial orientations and textures observed in such films.Thin films of nominally Bi2Sr2CaCu2Ox were deposited on MgO using molecular beam epitaxy (MBE). These films were in situ grown (during growth oxygen was incorporated and the films were not oxygen post-annealed) and shuttering was used to encourage c axis growth. Other papers report the details of the synthesis procedure. The films were characterized using x-ray diffraction (XRD) and transmission electron microscopy (TEM).


2003 ◽  
Vol 775 ◽  
Author(s):  
Donghai Wang ◽  
David T. Johnson ◽  
Byron F. McCaughey ◽  
J. Eric Hampsey ◽  
Jibao He ◽  
...  

AbstractPalladium nanowires have been electrodeposited into mesoporous silica thin film templates. Palladium continually grows and fills silica mesopores starting from a bottom conductive substrate, providing a ready and efficient route to fabricate a macroscopic palladium nanowire thin films for potentially use in fuel cells, electrodes, sensors, and other applications. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicate it is possible to create different nanowire morphology such as bundles and swirling mesostructure based on the template pore structure.


Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 456
Author(s):  
Fahad A. Alharthi ◽  
Hamdah S. Alanazi ◽  
Amjad Abdullah Alsyahi ◽  
Naushad Ahmad

This study demonstrated the hydrothermal synthesis of bimetallic nickel-cobalt tungstate nanostructures, Ni-CoWO4 (NCW-NPs), and their phase structure, morphology, porosity, and optical properties were examined using X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS), high resolution Transmission electron microscopy (HR-TEM), Brunauer-Emmett-Teller (BET) and Raman instruments. It was found that as-calcined NCW-NPs have a monoclinic phase with crystal size ~50–60 nm and is mesoporous. It possessed smooth, spherical, and cubic shape microstructures with defined fringe distance (~0.342 nm). The photocatalytic degradation of methylene blue (MB) and rose bengal (RB) dye in the presence of NCW-NPs was evaluated, and about 49.85% of MB in 150 min and 92.28% of RB in 90 min degraded under visible light. In addition, based on the scavenger’s study, the mechanism for photocatalytic reactions is proposed.


2015 ◽  
Vol 14 (04) ◽  
pp. 1550011 ◽  
Author(s):  
A. Sharma ◽  
M. Tomar ◽  
V. Gupta ◽  
A. Badola ◽  
N. Goswami

In this paper gas sensing properties of 0.5–3% polyaniline (PAni) doped SnO 2 thin films sensors prepared by chemical route have been studied towards the trace level detection of NO 2 gas. The structural, optical and surface morphological properties of the PAni doped SnO 2 thin films were investigated by performing X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Raman spectroscopy measurements. A good correlation has been identified between the microstructural and gas sensing properties of these prepared sensors. Out of these films, 1% PAni doped SnO 2 sensor showed high sensitivity towards NO 2 gas along with a sensitivity of 3.01 × 102 at 40°C for 10 ppm of gas. On exposure to NO 2 gas, resistance of all sensors increased to a large extent, even greater than three orders of magnitude. These changes in resistance upon removal of NO 2 gas are found to be reversible in nature and the prepared composite film sensors showed good sensitivity with relatively faster response/recovery speeds.


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