High Temperature Powder Camera Research Articles

Thermal Expansion of Rutile and Anatase

Lattice parameters of rutile and anatase were determined from 30° to 650°C and from 28° to 712°C, respectively, using a high-temperature powder camera. These data were used to evaluate the coefficients of thermal expansion of rutile and anatase. The temperature dependence of the coefficients, α11 and α1, parallel and perpendicular to the principal axis, respectively, are represented by the equations: Rutile: Anatase: The relative magnitudes of the coefficients of thermal expansion of these polymorphs are explained in terms of the interionic distances.

X-ray studies on the thermal expansion of ruthenium dioxide

A precise X-ray determination of the lattice constants of ruthenium dioxide, RuO2, has been made in the temperature range 30° to 702°C using a Unicam 19 cm high-temperature powder camera. It has been observed that the c parameter decreases with increasing temperature as in the case of FeF2 and CrO2 which also have a ruffle-type structure.

Determination of thermal expansion of germanium, rhodium and iridium by X-rays

The lattice parameters of germanium, rhodium and iridium were measured with a Unicam 19 cm high-temperature powder camera; the following equations represent the results: Ge: at = 5.6569 + 34.22 × 10−6t + 10.17 × 10−9t2 − 0.66 × 10−12t3, Rh: at = 3.8026 + 29.27 × 10−6t + 10.49 × 10−9t2 + 0.54 × 10−12t3, Ir: at = 3.8383 + 23.52 × 10−6t + 4.92 × 10−9t2 + 0.89 × 10−12t3. Thermal expansion coefficients and Grüneisen parameters were also calculated.

Precision lattice parameters and thermal expansion of calcite

Precision lattice parameters of calcite have been determined at different temperatures by X-ray method in the temperature range 28° to 524°C using a Unicam 19 cm high temperature powder camera. The data has been used to evaluate the coefficients of thermal expansion, α∥ and α⊥, by a graphical method. Temperature dependence of the coefficients are represented by the following equations: α ∥ = 24·670 × 10 −6 + 1·742 × 10 −8 t−5·141 × 10 −12 t 2 α ⊥ = 3·660 × 10 −6 − 7·112 × 10 −10 t−3·339 × 10 −12 t 2 where t is in °C.

Unit-cell dimensions of Ni-Pd alloys at 25 and 900°C

Abstract : The cell constants of Ni-Pd alloys were measured at 25 and 900C with a Unican, 19 cm, high-temperature x-ray powder camera using Cu K alpha radiation. The At.% of Pd was varied from 0 to 100%. The cell constants and molar volume are given and compared with published data.

X-ray studies on the thermal expansion of zinc fluoride, manganous fluoride and cobaltous fluoride

A precision determination of the lattice parameters of zinc fluoride (ZnF2), manganous fluoride (MnF2) and cobaltous fluoride (CoF2) has been made in the temperature range 25 to 600° C., using a Unicam 19 cm. high temperature powder camera. From these data the coefficients of thermal expansion α| and α⊥ have been evaluated by a graphical method. For zinc and manganous fluorides, α| is greater than α⊥ as in the case of other crystals of rutile type of structure, whereas cobaltous fluoride is anomalous in its behaviour having a greater value for α⊥.

X-ray investigation of bredigite

The X-ray work described below has been done on crystals of bredigite obtained from two different sources, the natural mineral from Scawt Hill, County Antrim, and the synthetic mineral from spiegeleisen slags. Both types of material have been fully deseribed by Tilley and Vincent (1948). Their analysis shows that the slag mineral is a calcium orthosilicate in which Ca is partly replaced by Mg, Mn, and Ba, the extent of the replacement being represented by the formula (Cal.59Ba0.08Mg0.31Mn0.09)SiO4. Tilley and Vincent conclude that this orthorhombic (pseudo-hexagonal) phase is identical with the high-temperature form α' of pure Ca2SiO4, the existence of which was suggested by Bredig (1943a), and confirmed by TrSmel (1949) using a high-temperature powder camera. Bredig (1943a) also suggests, on the basis of a comparison of X-ray powder patterns, that the crystal structure of α'-Ca2SiO4 is similar to that of β-K2SO4. The present single-crystal work was originally undertaken in order to investigate the structure of α'-Ca2SiO4 more fully.

Thermal dilation of copper

The prediction that certain cubic metals may not be precisely cubic throughout a range of temperature below their melting points led to the present investigation. Pure copper was chosen as the cubic metal to examine for anisotropy in its thermal dilation, and the (024) and the (331) planes were chosen in the lattice. Temperatures for examination ranged between 18°–770°C, using a 19-cm high-temperature powder camera by Unicam of Cambridge, England. Plotting the lattice constant vs. temperature, the thermal dilation of pure copper was found to be isotropic throughout the temperature range investigated.