Residual Stresses in Co-Sputtered Films of Ta and Si on Substrates of Silicon and Oxide.

1983 ◽  
Vol 25 ◽  
Author(s):  
C. C. Goldsmith ◽  
D. R. Campbell ◽  
S. Mader
Keyword(s):  
Thermal Expansion ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Intrinsic Stress ◽  
Temperature Stresses ◽  
X Ray ◽  
Sputtered Films ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Deposited Films

ABSTRACTWe have measured the stresses in TaSi. films both as a function of annealing temperature and of composition of the as-deposited films. Substrates of Si, polysilicon and SiO2 were used. The residual, room temperature stresses in samples annealed at 900°C are noticeably dependent on the initial Si/Ta ratio. This effect appears to to be related to microstructural differences between Si-rich and Ta-rich films. The stresses are largely due to the mismatch of thermal expansion coefficients (TEC) between the silicide and silicon although there is also evidence that samples annealed at lower temperatures (500°C) may have a sizable component of intrinsic stress as well. Despite tensile stresses as high as 1500 MPa, the x-ray topographs of Si wafers with patterned silicide/polysilicon structures show that no substrate dislocations are present after- annealing.

Behaviors of the Zr–1.0Sn–0.39Nb–0.31Fe–0.05Cr Alloy at High Temperature

2011 ◽  
Vol 399-401 ◽  
pp. 80-84
Author(s):  
Yi Yuan Tang ◽  
Jie Li Meng ◽  
Kai Lian Huang ◽  
Jian Lie Liang
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
High Temperature ◽  
Oxide Film ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thin Oxide Film ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

Phase transformation of the Zr-1.0Sn-0.39Nb-0.31Fe-0.05Cr alloy was investigated by high temperature X-ray diffraction (XRD). The XRD results revealed that the alloy contained two precipitates at room temperature, namely β-Nb and hexagonal Zr(Nb,Fe,Cr,)2. β-Nb was suggested to dissolve into the α-Zr matrix at the 580oC. Thin oxide film formed at the alloy’s surface was identified as mixture of the monoclinic Zr0.93O2and tetragonal ZrO2, when the temperature reached to 750oC and 850 oC. The thermal expansion coefficients of αZr in this alloy was of αa = 8.39×10-6/°C, αc = 2.48×10-6/°C.

Intrinsic and Thermal Stress in Gallium Nitride Epitaxial Films

1996 ◽  
Vol 449 ◽  
Author(s):  
J. W. Ager ◽  
T. Suski ◽  
S. Ruvimov ◽  
J. Krueger ◽  
G. Conti ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Thermal Expansion ◽  
Thermal Stress ◽  
Growth Temperature ◽  
Room Temperature ◽  
Intrinsic Stress ◽  
Experimental Methodology ◽  
Thermal Expansion Coefficients ◽  
Si Doped ◽  
Expansion Coefficients

ABSTRACTStrain in GaN epitaxial layers at room temperature is measured with three complementary methods: Raman spectroscopy (via shifts of phonon frequencies), low temperature photoluminescence (via shifts of band-edge luminescence), and X-ray diffraction (via shifts in lattice spacings). GaN films grown on the c-plane of sapphire tend to be in compression. Increasing the Si-dopant concentration (up to 1019 cm−3) is observed to add compressive strain to the layer. Axially resolved measurements obtained by micro-Raman in 4 μm thick Si-doped films reveal strain relaxation toward the sample surface at Si concentrations above 1018 cm−3. Mg- and Si-doped GaN films on SiC substrates are found to be in tension. An experimental methodology is presented that separates two contributions to the room temperature residual stress in GaN epilayers: (1) the thermal stress due to differences in the thermal expansion coefficients of the epilayer and substrate and (2) the intrinsic stress, which is influenced by the growth conditions. We measure stress as a function of temperature up to 325 C, about one-third of the growth temperature, by monitoring the frequency of the E2 phonon mode by Raman spectroscopy. A high-quality bulk single crystal of GaN is used as a strain-free standard. Over this temperature range, most layers behave elastically; the observed stress trends are well-fit by a thermal expansion model using previous reported values of the thermal expansion coefficients of GaN and the substrates. The intrinsic stress states at the growth temperature for films grown on sapphire and SiC are predicted to be tensile and compressive, respectively, in agreement with the a-plane lattice coefficient mismatch.

The crystal structure and thermal expansion of the CCl4 adduct of Dianin's compound

1990 ◽  
Vol 68 (8) ◽  
pp. 1352-1356 ◽  
Author(s):  
Walter Abriel ◽  
André Du Bois ◽  
Marek Zakrzewski ◽  
Mary Anne White
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Dianin's Compound

The crystal structure of the title compound has been determined by single crystal X-ray diffraction data collected at 293 K, and refined to a final Rw of 0.057. The crystals are rhombohedral, space group [Formula: see text], with a = 27.134(8) Å, c = 10.933(2) Å, and Z = 18. The mole ratio of Dianin's compound (4-p-hydroxyphenyl-2,2,4-trimethylchroman) to CCl4 is 6:1. The guest molecules are disordered. X-ray powder diffraction was carried out in the temperature range from 10 to 300 K. From this, the thermal expansion coefficients for the a- and c-axes and the volume have been determined. Keywords: thermal expansion, crystal structure, clathrate.

Structure and Thermal Expansion Behavior of Dy2-xGdxMo4O15 Solid Solution

2008 ◽  
Vol 368-372 ◽  
pp. 1665-1667
Author(s):  
M.M. Wu ◽  
X.L. Xiao ◽  
Y.Z. Cheng ◽  
J. Peng ◽  
D.F. Chen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Thermal Expansion ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Expansion Coefficients ◽  
Cell Volumes

A new series of solid solutions Dy2-xGdxMo4O15 (x = 0.0-0.9) were prepared. These compounds all crystallize in monoclinic structure with space group P21/c. The lattice parameters a, b, c and unit cell volumes V increase almost linearly with increasing gadolinium content. The intrinsic thermal expansion coefficients of Dy2-xGdxMo4O15 (x = 0.0 and 0.25) were obtained in the temperature range of 25 to 500°C with high-temperature X-ray diffraction. The correlation between thermal expansion and crystal structure was discussed.

Crystal Distortion Associated with Magnetic Ordering in Alpha Iron Oxide and Manganese Carbonate

1972 ◽  
Vol 16 ◽  
pp. 390-395 ◽  
Author(s):  
W. S. McCain ◽  
D. L. Albright
Keyword(s):  
Thermal Expansion ◽  
Lattice Constant ◽  
Room Temperature ◽  
Axial Ratio ◽  
Manganese Carbonate ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Position Parameter ◽  
Oxygen Distance

AbstractThe magnetic crystal disrortion of weakly ferromagnetic α-Fe2O3 was investigated by x-ray diffraction techniques. Here crystal distortion is taken as the temperature dependent changes of lattice constants and thermal expansion coefficients. Moreover, the oxygen position parameter and the carbon-oxygen distance of MnCO3 were determined.The lattice constants and thermal expansion coefficients of α-Fe2O3 were measured from room temperature down to 243°K. The crystal distortion, as measured by the changes in lattice constants, thermal expansion coefficients and axial ratio, was found to be highly anisotropic. The co hexagonal lattice constant was influenced very slightly by magnetic distortion; it changed only by 0.01 percent between room temperature and the Morin temperature of 254°K. On the other hand, the ao lattice constant changes by 0.11 percent between room temperature and the Morin temperature. The thermal expansion coefficients of the lattice constants showed a similar contrast. The co coefficient was found to be independent of temperature from room temperature down to the Morin temperature. However, in the same temperature range, the ao coefficient showed an anomalous increase with decreasing temperature. In addition, the ao coefficient showed an infinite discontinuity at the Morin temperature.The change in the axial ratio with temperature suggests that the net weak ferromagnetic moment of α-Fe2O3 reaches a maximum at 275°K.The oxygen position parameter, x, in MnCO3 as determined from two reflections has a value of 0.2702 ± 0.001. The carbon-oxygen distance as calculated from the lattice constants and the oxygen position parameter is 1.29 ±0.002 Å. This value is another confirmation of the Pauling theory of the resonating carbonate structure.

scholarly journals An examination of the thermal expansion of urea using high-resolution variable-temperature X-ray powder diffraction

2005 ◽  
Vol 38 (6) ◽  
pp. 1038-1039 ◽  
Author(s):  
Robert Hammond ◽  
Klimentina Pencheva ◽  
Kevin J. Roberts ◽  
Patricia Mougin ◽  
Derek Wilkinson
Keyword(s):  
Thermal Expansion ◽  
High Resolution ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
Polymorphic Transformations ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Cell Dimensions ◽  
Expansion Coefficients ◽  
Unit Cell Dimensions

Variable-temperature high-resolution capillary-mode powder X-ray diffraction is used to assess changes in unit-cell dimensions as a function of temperature over the range 188–328 K. No evidence was found for any polymorphic transformations over this temperature range and thermal expansion coefficients for urea were found to be αa= (5.27 ± 0.26) × 10−5 K−1and αc= (1.14 ± 0.057) × 10−5 K−1.

A temperature-dependent structure study of gem-quality hibonite from Myanmar

2010 ◽  
Vol 74 (5) ◽  
pp. 871-885 ◽  
Author(s):  
M. Nagashima ◽  
T. Armbruster ◽  
T. Hainschwang
Keyword(s):  
Room Temperature ◽  
Structure Study ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Trigonal Bipyramidal ◽  
Expansion Coefficients ◽  
Increasing Temperature ◽  
Length Distortion

AbstractThe structure of hibonite from Myanmar (space group P63/mmc, Z = 2, at room temperature a = 5.5909(1), c = 21.9893(4) Å), with simplified formula CaAl12O19 and composition (Ca0.99Na0.01)Σ1.00 was investigated between temperatures of 100 K and 923 K by single-crystal X-ray diffraction methods. Structure refinements have been performed at 100, 296, 473 and 923 K. In hibonite from Myanmar, Ti substitutes for Al mainly at the octahedral Al4 site and, to a lesser degree, at the trigonal bipyramidal site, Al2. The Al4 octahedra build face-sharing dimers. If Ti4+ substitutes at Al4, adjacent cations repulse each other for electrostatic reasons, leading to off-centre cation displacement associated with significant bond-length distortion compared to synthetic (Ti-free) CaAl12O19. Most Mg and smaller proportions of Zn and Si are assigned to the tetrahedral Al3 site. 12-coordinated Ca in hibonite replaces oxygen in a closest-packed layer. However, Ca is actually too small for this site and engages in a ‘rattling-type’ motion with increasing temperature. For this reason, Ca does not significantly increase thermal expansion coefficients of hibonite. The expansion of natural Ti,Mg-rich hibonite between 296 and 923 K along the x and the z axes is αa = 7.64×10–6 K–1 and αc = 11.19×10–6 K–1, respectively, and is thus very similar to isotypic, synthetic CaAl12O19 and LaMgAl11O19 (LMA).

Influence of Nitride on Sinterability of the Composite of Lithium Aluminum Silicate and Silicon Carbide

2006 ◽  
Vol 317-318 ◽  
pp. 177-180 ◽  
Author(s):  
Mabito Iguchi ◽  
Motohiro Umezu ◽  
Masako Kataoka ◽  
Hiroaki Nakamura ◽  
Mamoru Ishii
Keyword(s):  
Silicon Carbide ◽  
Thermal Expansion ◽  
Melting Point ◽  
Liquid Phase ◽  
Room Temperature ◽  
Aluminum Silicate ◽  
Lithium Aluminum ◽  
Sintering Process ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

Ceramics with zero thermal expansion coefficients at room temperature (293K) were investigated. We found the thermal expansion coefficient was controlled by a compounding ratio of lithium aluminum silicate (LAS) and silicon carbide (SiC), which have negative and positive thermal expansion coefficients respectively. Although it was difficult to densify the composite of the LAS and SiC (LAS/SiC) in the sintering process, an addition of nitride improved the sinterability of the LAS/SiC. In order to examine the effect of the nitride additive, at first, the melting point of the LAS with silicon nitride (Si3N4) or aluminum nitride was measured by TG-DTA. The melting point of the LAS decreased with existence of nitride. It is believed that the densification of the LAS/SiC was promoted by the nitride, because the nitride causes the LAS/SiC to form a liquid phase, thereby decreasing the melting point. Next, the lattice constant of the LAS with Si3N4 was measured by XRD and it was verified that the a-axis was longer and the c-axis was shorter than those of the LAS without additive. It is supposed that this phenomenon is due to the substitution of nitrogen for oxygen in the LAS lattice, and the decrease of the melting point of the LAS with nitride seems to be influenced by this substitution of nitrogen.

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