https://www.umsl.edu/~chickosj/JSCPUBS/dsccal.pdf

Reference materials for calorimetry and differential thermal analysis

Thermodynamic properties of quartz, cristobalite and amorphous SiO2: drop calorimetry measurements between 1000 and 1800 K and a review from 0 to 2000 K

A revised equation is proposed to represent and extrapolate the heat capacity of minerals as a function of temperature: C
P=k0+k1
T
−0.5+k2
T
−2+k3
T
−3 (where k1, k2≤0). This equation reproduces calorimetric data within the estimated precision of the measurements, and results in residuals for most minerals that are randomly distributed as a function of temperature. Regression residuals are generally slightly greater than those calculated with the five parameter equation proposed by Haas and Fisher (1976), but are significantly lower than those calculated with the three parameter equation of Maier and Kelley (1932). The revised equation ensures that heat capacity approaches the high temperature limit predicted by lattice vibrational theory (C
P=3R+α2VT/β). For 16 minerals for which α and β have been measured, the average C
Pat 3,000 K calculated with the theoretically derived equation ranges from 26.8±0.8 to 29.3±1.9 J/(afu·K) (afu = atoms per formula unit), depending on the assumed temperature dependence of α. For 91 minerals for which calorimetric data above 400 K are available, the average C
Pat 3,000 K calculated with our equation is 28.3±2.0 J/(afu·K). This agreement suggests that heat capacity extrapolations should be reliable to considerably higher temperatures than those at which calorimetric data are available, so that thermodynamic calculations can be applied with confidence to a variety of high temperature petrologic problems. Available calorimetric data above 250 K are fit with the revised equation, and derived coefficients are presented for 99 minerals of geologic interest. The heat capacity of other minerals can be estimated (generally within 2%) by summation of tabulated ‘oxide component’ C
Pcoefficients which were obtained by least squares regression of this data base.

/pdf/heat-capacity-of-minerals-in-the-system-na-2-o-k-2-o-cao-mgo-41pin1q2iw.pdf

Heat capacity of minerals in the system Na 2 O-K 2 O-CaO-MgO-FeO-Fe 2 O 3 -Al 2 O 3 -SiO 2 -TiO 2 -H 2 O-CO 2 : representation, estimation, and high temperature extrapolation

Differential scanning calorimeters (DSCs) are widely used for temperature, heat capacity, and enthalpy measurements in the range from subambient to high temperatures. The present recommendations describe procedures and reference materials (RMs) for the calibration of DSCs. The recommendations focus on the calibration of the response of the instrument and on the estimation of the measurement uncertainty. The procedures for temperature, enthalpy, and heat-flow rate calibration are given in detail. Calibration on cooling has also been considered. Recommended RMs are listed, and the relevant properties of these materials are discussed.

Standards, calibration, and guidelines in microcalorimetry. Part 2. Calibration standards for differential scanning calorimetry : (IUPAC technical report)

Solution-grown crystals of hydroxyapatite were sintered into polycrystalline oxyhydroxyapatite bodies, using the range 1050 to 1450°C. The heat capacity, thermal diffusivity, and thermal conductivity of the sintered bodies were measured by the laser flash method at 130–1000 K. The sintered bodies were 94.4 to 99.4% of theoretical density and 0.8 to 12 μm in grain size. Sintering is accompanied by grain growth and by vacancy formation and cell contraction due to thermal dehydration. Typical values of the heat capacity, thermal diffusivity, and thermal conductivity at room temperature are 0.73 J/g K, 0.0057 cm2/s and 0.013 J/s cm K, respectively. Low-temperature thermal conductivity increased with increasing temperature, similarly to that of amorphous solids. This odd behavior is discussed in terms of phonon mean free path.

Preparation and Thermal Properties of Dense Polycrystalline Oxyhydroxyapatite

The relative enthalpy of NBS Standard Reference Material No. 720 (99.98 percent pure, single-crystal α-Al2O3, a calorimetrie heat-capacity standard) was measured over the range 273 to 1173 K by the drop method using a highly precise Bunsen ice calorimeter. Enthalpy data over the same temperature interval were obtained also on the Calorimetry Conference Sample of this substance. These results are believed to be more accurate than similar NBS results on the latter sample published in 1956, and show no significant discontinuity with the NBS data on the same substance that covered the ranges 13 to 380 K and 1173 to 2257 K. The average deviation from the mean for all enthalpy measurements on the SKM 720 sample was 0.017 percent, and the smooth enthalpy values derived from the data were estimated to be accurate to 0.1 percent. The precautions observed in order to minimize measuring errors are described in detail. The data are compared with many sets of the most reliable published data available and new recommended values for the thermodynamic functions of α-Al2O3 are presented for the interval 0 to 1200 K.

/pdf/measurement-of-the-relative-enthalpy-of-pure-a-al2o3-nbs-28m0gof03k.pdf

Measurement of the relative enthalpy of pure a-Al2O3 (NBS heat capacity and enthalpy Standard Reference Material No. 720) from 273 to 1173 K

Calibration standards for differential scanning calorimetry I. Zinc: absolute calorimetric measurement of Tfus and ΔfusHm

The enthalpy of a high-purity sample of anhydrous crystalline aluminum trifluoride, AlF3, relative to that at 0 °C (273.15 °K), was precisely measured with an ice calorimeter and a "drop" method at 18 temperatures starting at 50 °C and proceeding in 50-deg steps to 900 °C (1173.15 °K). Thirty additional enthalpy measurements between 450 and 453 °C revealed a gradual transition. A simple general relation for the progress of transition when impurity is in solid solution is derived. The relation fits the observed transition data and indicates a first-order transition temperature of 455 °C (728 °K). X-ray powder patterns on the sample, measured in the Crystallography Section of the NBS, established the existence of a phase transition by showing not only the known hexagonal structure at room temperature (even after violent quenching from above the transition temperature region) but a new, simple-cubic structure at 570 °C (843 °K). The smooth heat-capacity curve formulated from the data merges very smoothly with that representing published precise low-temperature data. The common thermodynamic properties were derived, and are tabulated at and above 273.15 °K, with extrapolation up to 1600 °K.

/pdf/measured-relative-enthalpy-of-anhydrous-crystalline-aluminum-11vdc0qd62.pdf

Measured Relative Enthalpy of Anhydrous Crystalline Aluminum Trifluoride, AlF3, from 273 to 1173 °K and Derived Thermodynamic Properties from 273 to 1600 °K.

Measurement of the average total decay power of two plutonium heat sources in a Bunsen ice calorimeter

The general principles of heat-capacity or enthalpy calorimetry by the method of mixtures have been presented elsewhere together with a copious bibliography.(1) To briefly recapitulate, this experimental approach is well suited to highly accurate and precise measurement of the heat capacity of nonreacting, solid or liquid systems in any condition of subdivision (including massive, crystallites, and powders). It is also of great use in measuring heats of phase changes and their associated temperatures. Usually, the basic datum obtainable through this method is the total enthalpy change of the system under study upon rapid transfer from an initial equilibrium state in a high-temperature furnace to a second equilibrium state in the calorimeter. Thus the chief sources of error are limited to those in temperature measurement and attainment of equilibrium in the furnace, in accurately accounting for heat losses during a sample transfer, in measurement of the heat transferred from the sample to the calorimeter, and in attainment of a reproducible thermodynamic state of the sample in the calorimeter. The equipment required is a mix of custom-fabricated parts, well within the capability of any competent instrument shop, and commercially-obtainable heating, temperature-measurement, and temperature-control components. This chapter presents a specific design and operating criteria for a phase-change calorimetric system using purified water as the working substance and capable of operating at a precision level of 0.01%. and an accuracy level of 0.1%. Except for the measurement, control, and recording of temperature, the system is manual in operation.

David A. Ditmars

Papers

Measurement of the relative enthalpy of pure a-Al2O3 (NBS heat capacity and enthalpy Standard Reference Material No. 720) from 273 to 1173 K

Calibration standards for differential scanning calorimetry I. Zinc: absolute calorimetric measurement of Tfus and ΔfusHm

Measured Relative Enthalpy of Anhydrous Crystalline Aluminum Trifluoride, AlF3, from 273 to 1173 °K and Derived Thermodynamic Properties from 273 to 1600 °K.

Measurement of the average total decay power of two plutonium heat sources in a Bunsen ice calorimeter

Phase-Change Calorimeter for Measuring Relative Enthalpy in the Temperature Range 273.15 to 1200 K