THE THERMAL EXPANSION OF ALKALI HALIDES

1965 ◽  
Vol 43 (10) ◽  
pp. 1853-1866 ◽  
Author(s):  
P. P. M. Meincke ◽  
G. M. Graham
Keyword(s):  
Thermal Expansion ◽  
Low Temperatures ◽  
Linear Thermal Expansion ◽  
Alkali Halides ◽  
Temperature Limit ◽  
Detectable Change ◽  
Fabry Perot ◽  
Interionic Potential ◽  
Best Fit ◽  
Rigid Ion Model

Measurements have been made of the coefficient of linear thermal expansion of NaCl, Nal, KCl, and KBr over the temperature range from 7 °K to 300 °K. The measurements were made by monitoring the changes in length of a Fabry–Perot etalon, whose spacer was of the material being studied, as it slowly warmed from liquid-helium temperatures. The detectable change in length of the 2-in. specimen was about 2 Å. The results are analyzed by reducing them to values of the Grueneisen γ. The temperature variation of γ at high temperatures is used to obtain values of γ (2s), which are compared with new calculations on a rigid-ion model to give the best fit to the Born exponent for the non-Coulomb interionic potential. The data for low temperatures are not sufficiently accurate to justify detailed analysis; there is some indication that the apparent low-temperature limit of γ is, in fact, the value at a minimum.

scholarly journals Thermal Properties of Stabilized Zirconia at Low Temperatures

1985 ◽  
Vol 38 (4) ◽  
pp. 617 ◽  
Author(s):  
JG Collins ◽  
SJ Collocott ◽  
GK White
Keyword(s):  
Heat Capacity ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Low Temperatures ◽  
Linear Thermal Expansion Coefficient ◽  
Linear Thermal Expansion ◽  
Stabilized Zirconia ◽  
Elastic Data

The linear thermal expansion coefficient a from 2 to 100 K and heat capacity per gram cp from 0�3 to 30 K are reported for fully-stabilized zirconia containing a nominal 16 wt.% (9 mol.%) of yttria. The heat capacity below 7 K has been analysed into a linear (tunnelling?) term, a Schottky term centred at 1�2 K, a Debye term (e~ = 540 K), and a small T5 contribution. The expansion coefficient is roughly proportional to T from 5 to 20 K and gives a limiting lattice Griineisen parameter 'Yo ::::: 5, which agrees with that calculated from elastic data.

Thermal Expansion of Alkali Halides at Low Temperatures

1968 ◽  
Vol 167 (3) ◽  
pp. 814-817 ◽  
Author(s):  
T. H. K. Barron ◽  
Alicia Batana
Keyword(s):  
Thermal Expansion ◽  
Low Temperatures ◽  
Alkali Halides

scholarly journals Tests of Cryogenic Fabry–Perot Cavity with Mirrors on Different Substrates

2019 ◽  
Vol 9 (2) ◽  
pp. 230
Author(s):  
Mickail Kuvshinskii ◽  
Sergei Oreshkin ◽  
Sergei Popov ◽  
Valentin Rudenko ◽  
Ivan Yudin ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Calcium Fluoride ◽  
Low Temperatures ◽  
Optical Materials ◽  
Optical Glass ◽  
Temperature Range ◽  
Low Thermal Expansion ◽  
Fabry Perot ◽  
Integral Characteristics ◽  
Birefringence Effect

Experiments were performed with Fabry–Perot optical resonators in vacuum at low temperatures. Mirrors were applied on substrates of various optical materials. An infrared laser with a wavelength of 1.064 microns was used. The pump power at the maximum could reach 450 mW. The evolution of the optical properties of the FP cavity was traced in the temperature range 300–10 K. The main parameters measured were the integral characteristics of the FP resonances–sharpness (finesse) and contrast of interference. Three types of substrates were tested: a sitall, an optical glass with ultra low thermal expansion (ULE); sapphire; and calcium fluoride. During cooling, the degradation of the integral characteristics of the FP cavity was observed for the sitall mirrors due to the loss of the properties of ULE, and for sapphire mirrors due to the birefringence effect. The satisfactory constancy of the integral characteristics of the FP resonator on calcium fluoride was demonstrated in the entire temperature range studied.

THERMAL EXPANSION OF SINGLE CRYSTALS OF ZINC AT LOW TEMPERATURES

1965 ◽  
Vol 43 (7) ◽  
pp. 1328-1333 ◽  
Author(s):  
D. A. Channing ◽  
S. Weintroub
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Single Crystals ◽  
Low Temperatures ◽  
Linear Thermal Expansion ◽  
Optical Interference ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Good Agreement

The linear thermal expansion coefficients αψ of two single crystals of Zn of orientations ψ = 10.8° and 63.9 ° with the hexad axis were measured over the temperature range of about 20–270 °K using an absolute Fizeau optical interference technique. The two principal coefficients, [Formula: see text] and [Formula: see text], corresponding to ψ = 0° and 90 ° respectively, were calculated from the Voigt relation, and their values are compared with previously reported experimental data. Above 60 °K there is good agreement with previous work, and below 60 °K the results confirm, in general, the data obtained by McCammon and White. The Grüneisen parameter γ is essentially constant at about 2.1 in the range 100–270 °K, but below 100 °K γ rises appreciably with decreasing temperature and reaches the value of about 3.5 at 20 °K.

Crystallization and Second-Order Transitions in Silicone Rubbers

1951 ◽  
Vol 24 (2) ◽  
pp. 366-373 ◽  
Author(s):  
C. E. Weir ◽  
W. H. Leser ◽  
L. A. Wood
Keyword(s):  
Thermal Expansion ◽  
Volume Change ◽  
Silicone Rubber ◽  
Low Temperatures ◽  
Linear Thermal Expansion ◽  
Second Order ◽  
Order Transition ◽  
General Electric ◽  
Second Order Transition ◽  
Silicone Rubbers

Abstract In the course of an investigation to determine which rubbers might be suitable for use at low temperatures, interferometric measurements of the length-temperature relationships of silicone rubbers have been made. Crystallization was found between −60° and −67° C in Dow-Corning Silastic X-6160 and in General Electric 9979G silicone rubber, the latter of which contains no filler. Crystallization between −75° and −85° C was found in Silastic 250. Melting occurred over a range of temperature above the temperature of crystallization. The volume change on crystallization varied from 2.0 to 7.8 per cent. No crystallization or melting phenomena were observed in Silastic X-6073 between −180° and +100° C. All types of silicone rubber exhibited a second-order transition at about −123° C, the lowest temperature at which such a transition has been observed in a polymer. The coefficient of linear thermal expansion of silicone rubbers containing no filler was found to be about 40×10−5/degree C between −35° and 0° C.

THE COEFFICIENT OF THERMAL EXPANSION OF VARIOUS CUBIC METALS BELOW 100 °K

1965 ◽  
Vol 43 (2) ◽  
pp. 193-219 ◽  
Author(s):  
D. B. Fraser ◽  
A. C. Hollis Hallett
Keyword(s):  
Thermal Expansion ◽  
Noble Metals ◽  
Coefficient Of Thermal Expansion ◽  
Linear Thermal Expansion ◽  
Electronic Contribution ◽  
Electronic Effects ◽  
Interferometric Method ◽  
Lattice Contribution ◽  
Cubic Metals ◽  
Fabry Perot

Measurements have been made of the coefficient of linear thermal expansion, α, of Cu, Ag, Au, Al, α-Fe, and Ni at temperatures below 100 °K using an interferometric method in which the spacer between the optical flats of a Fabry–Perot-type interferometer was made of the material studied. The lowest temperatures at which values of α are given are about 20 °K (Cu, Ag), 11 °K (Au), 25 °K (Al, Fe), and 32 °K (Ni). The results are discussed in terms of the Gruneisen parameter γ which, for Cu, Ag, and Au, is approximately constant at high temperatures, but tends to rise slightly as the temperature is reduced towards the lowest temperatures of measurement. For Al, a correction for the electronic contribution is applied below 40 °K to deduce the lattice contribution γL, which rises more spectacularly at low temperatures than the results for the noble metals. For Fe, separation of α into two contributions, one from the lattice and one from the combined magnetic and electronic effects, may be made, giving γL = 1.45; the combined magnetic and electronic contribution is very small.

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