Impact of embedded voids on thin-films with high thermal expansion coefficients mismatch

ABSTRACTHigh resolution pattern transfers in the nano-scale regime have been considerable challenges in ‘soft lithography’ to achieve nanodevices with enhanced performances. In this technology, the resolution of pattern integrations is significantly rely on the materials' properties of polydimethylsiloxane (PDMS) stamps. Since commercial PDMS stamps have shown limitations in nano-scale resolution soft lithography due to their low physical toughness and high thermal expansion coefficients, we developed stiffer, photocured PDMS silicon elastomers designed, specifically for nano-sized soft lithography and photopatternable nanofabrications.

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Organo-Soluble, Segmented Rigid-Rod Polyimides: Synthesis and Properties

MRS Proceedings ◽

10.1557/proc-227-3 ◽

1991 ◽

Vol 227 ◽

Cited By ~ 15

Author(s):

F. W. Harris ◽

S. L. C. Hsu ◽

C. J. Lee ◽

B. S. Lee ◽

F. Arnold ◽

...

Keyword(s):

Thin Films ◽

Thermal Expansion ◽

Glass Transition ◽

Oxidative Stability ◽

Organic Solvents ◽

Dielectric Constants ◽

Glass Transition Temperatures ◽

Thermal Expansion Coefficients ◽

Rigid Rod ◽

Expansion Coefficients

ABSTRACTSeveral segmented, rigid-rod polyimides have been prepared that are soluble in organic solvents in their fully imidized form. The polymers were prepared from commercial dianhydrides and 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFMB). Their intrinsic viscosities ranged from 1.0 to 4.9 dL/g. Tough, colorless films could be cast from m-cresol solutions at 100°C. The polymers had glass transition temperatures (Tgs) above 275°C and displayed outstanding thermal and thermo-oxidative stability. Fibers were prepared from the 3,3′,4,4′-tetracarboxybiphenyl dianhydride (BPDA) based polymers that had moduli of 130 GPa and tensile strengths of 3.2 GPa. The thermal expansion coefficients and dielectric constants of thin films (20–25 μm) of the polymers were as low as −2.40×10−6 and 2.5, respectively.

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On the thermal expansion coefficients of thin films

Sensors and Actuators A Physical ◽

10.1016/s0924-4247(00)00311-3 ◽

2000 ◽

Vol 84 (3) ◽

pp. 310-314 ◽

Cited By ~ 96

Author(s):

Weileun Fang ◽

Chun-Yen Lo

Keyword(s):

Thin Films ◽

Thermal Expansion ◽

Thermal Expansion Coefficients ◽

Expansion Coefficients

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Preparation and Characterization of Thermally Compatible Leucite-Reinforced Dental Ceramics

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.308-310.311 ◽

2011 ◽

Vol 308-310 ◽

pp. 311-314

Author(s):

Jin Wen ◽

Shu Zhen Sun

Keyword(s):

Thermal Expansion ◽

Dental Ceramics ◽

Dental Porcelain ◽

Thermal Expansion Coefficients ◽

High Thermal Expansion ◽

Coprecipitation Technique ◽

Thermal Compatibility ◽

The Common ◽

Expansion Coefficients

The high average thermal expansion required for thermal compatibility of dental porcelain with their substrate alloy is supplied by the mineral leucite (KAlSi2O6). In the research, the high thermal expansion coefficients phase leucite was prepared by coprecipitation technique. Three materials with formulae of K2O∶Al2O3∶SiO2= 1∶1∶x ( x=1.4, 2.0, 4.0 ) were investigated for differences in phase, thermal expansion. Unstoichiometric composition where K2O and Al2O3were added properly is advantage to leucite obtained. Coprecipitation processing produced fine leucite powder that would sinter at 1300°C, this temperature is about 200°C lower than of melting method. The average thermal expansion coefficients of leucite is 22.7×10-6/°Cfrom room temperature to 620°C,which is higher than the common porcelain. Changing in the leucite content of dental porcelain would results from thermal expansion coefficients of porcelain variation, which could be responsible for changes in porcelain-metal thermal compatibility.

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Variation of the Expansion Coefficient of Nanofluids With Temperature: A Correction for Conductivity Data

Journal of Nanotechnology in Engineering and Medicine ◽

10.1115/1.4024100 ◽

2012 ◽

Vol 3 (4) ◽

Cited By ~ 1

Author(s):

Efstathios E. Michaelides

Keyword(s):

Thermal Conductivity ◽

Thermal Expansion ◽

Conductivity Data ◽

Volumetric Fraction ◽

Solid Materials ◽

Strong Function ◽

Temperature Changes ◽

Thermal Expansion Coefficients ◽

High Thermal Expansion ◽

Expansion Coefficients

The two constituent phases of the nanofluids have thermal expansion coefficients that are significantly different. Moreover, the variability of the thermal expansion coefficients of fluids with temperature is significantly higher than that of solid materials. The mismatch of the thermal expansion coefficients creates changes of the volumetric fraction of solids with temperature changes. The changes can be significant with fluids that have high thermal expansion coefficients, such as refrigerants and fluids that operate close to their critical points. Since the thermal conductivity of nanofluids is a very strong function of the volumetric fraction of the nanoparticles, these changes of the volumetric fraction may cause significant effects on the thermal conductivity of the nanofluids, which must be accounted for in any design process.

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Thermal expansion of the new perovskite substrates DyScO3 and GdScO3

Journal of Materials Research ◽

10.1557/jmr.2005.0126 ◽

2005 ◽

Vol 20 (4) ◽

pp. 952-958 ◽

Cited By ~ 61

Author(s):

M.D. Biegalski ◽

J.H. Haeni ◽

S. Trolier-McKinstry ◽

D.G. Schlom ◽

C.D. Brandle ◽

...

Keyword(s):

Thin Films ◽

Thermal Expansion ◽

Rare Earth ◽

Lattice Spacing ◽

Epitaxial Thin Films ◽

X Ray Diffraction ◽

X Ray ◽

Thermal Expansion Coefficients ◽

Expansion Coefficients ◽

Increasing Temperature

The thermal expansion coefficients of DyScO3 and GdScO3 were determined from298 to 1273 K using x-ray diffraction. The average thermal expansion coefficients of DyScO3 and GdScO3 were 8.4 and 10.9 ppm/K, respectively. No phase transitions were detected over this range, though the orthorhombicity decreased with increasing temperature. These thermal expansion coefficients are similar to other oxide perovskites (e.g., BaTiO3 or SrTiO3), making these rare-earth scandates promising substrates for the growth of epitaxial thin films of many oxide perovskites that have similar lattice spacing and thermal expansion coefficients.

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