scholarly journals Low-temperature excess heat capacity in fresnoite glass and crystal

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Kensaku Nakamura ◽  
Yoshihiro Takahashi ◽  
Takumi Fujiwara
Keyword(s):  
Heat Capacity ◽  
Low Temperature ◽  
Excess Heat Capacity ◽  
Excess Heat ◽  
Temperature Excess

Origin of the low temperature excess heat capacity of isotopically substituted acetylsalicylic acid

2011 ◽  
Vol 514 (1-3) ◽  
pp. 62-65
Author(s):  
F. Schröder ◽  
B. Winkler ◽  
J.D. Bauer ◽  
E. Haussühl ◽  
B. Rivera Escoto ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Low Temperature ◽  
Acetylsalicylic Acid ◽  
Excess Heat Capacity ◽  
Excess Heat ◽  
Temperature Excess

The dependence of the boson peak on the thickness of Cu50Zr50 film metallic glasses

2021 ◽  
Author(s):  
Dongdong Li ◽  
Heng Chen ◽  
Bingyan Qu ◽  
Fabao Zhang ◽  
Rulong Zhou ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Low Temperature ◽  
Metallic Glasses ◽  
Excess Heat Capacity ◽  
Ultrathin Film ◽  
Boson Peak ◽  
Excess Heat ◽  
Temperature Excess

In this study, intensive calculations were performed to investigate the behavior of the low-temperature excess heat capacity of Cu50Zr50 ultrathin film metallic glasses.

scholarly journals Excess heat capacity and entropy of mixing along the hydroxyapatite-chlorapatite and hydroxyapatite-fluorapatite binaries

2021 ◽  
Vol 48 (12) ◽  
Author(s):  
Edgar Dachs ◽  
Artur Benisek ◽  
Daniel Harlov ◽  
Max Wilke
Keyword(s):  
Heat Capacity ◽  
Low Temperature ◽  
Density Functional ◽  
Hexagonal Phase ◽  
Exchange Process ◽  
Excess Heat Capacity ◽  
Heat Capacities ◽  
Scanning Calorimetry ◽  
Excess Heat ◽  
Ideal Mixing

AbstractThe heat capacity, Cp, of synthetic hydroxyapatite [Ca5(PO4)3OH–OH-Ap], as well as of ten compositions along the OH-Ap-chlorapatite (Cl-Ap) join and 12 compositions along the OH-Ap-fluorapatite (F-Ap) join have been measured using relaxation calorimetry (heat capacity option of the Physical Properties Measurement System—PPMS) and differential scanning calorimetry (DSC) in the temperature range of 5–764 K. Apatites along the Cl-OH and F-OH joins were synthesized at 1100 °C and 300 MPa in an internally heated gas pressure vessel via an exchange process between synthetic fluorapatite or chlorapatite crystals (200–500 μm size) and a series of Ca(OH)2-H2O solutions with specific compositions and amounts relative to the starting apatite. The standard third-law entropy of OH-Ap, derived from the low-temperature heat capacity measurements, is S° = 386.3 ± 2.5 J mol−1 K−1, which is ~ 1% lower than that resulting from low-temperature adiabatic calorimetry data on OH-Ap from the 1950’s. The heat capacity of OH-Ap above 298.15 K shows a hump-shaped anomaly centred around 442 K. Based on published structural and calorimetric work, this feature is interpreted to result from a monoclinic to hexagonal phase transition. Super ambient Cp up to this transition can be represented by the polynomial: $$C_{p}^{{\text{OH - Ap}}} {}_{{298K - 442K}}\left( {{\text{J mol}}^{ - 1} {\text{K}}^{- 1}} \right) = {1013.7-13735.5T^{{ - 0.5}}} + 2.616718\,10^{7} T^{{ - 2}} - 3.551381\,10^{9} T^{{ - 3}} .$$ C p OH - Ap 298 K - 442 K J mol - 1 K - 1 = 1013.7 - 13735.5 T - 0.5 + 2.616718 10 7 T - 2 - 3.551381 10 9 T - 3 . . The DSC data above this transition were combined with heat capacities computed using density functional theory and can be given by the Cp polynomial: $$C_{p}^{{\text{OH - Ap}}} {}_{{ >\,442K}}\left( {{\text{J mol}}^{ - 1} {\text{K}}^{- 1}} \right) = {877.2-11393.7 T^{ - 0.5}} + {5.452030\,10^{7}} \,T^{- {2}} - {1.394125\,10^{10}} \,T^{- {3}}$$ C p OH - Ap > 442 K J mol - 1 K - 1 = 877.2 - 11393.7 T - 0.5 + 5.452030 10 7 T - 2 - 1.394125 10 10 T - 3 . Positive excess heat capacities of mixing, ∆Cpex, in the order of 1–2 J mol−1 K−1, occur in both solid solutions at around 70 K. They are significant at these conditions exceeding the 2σ-uncertainty of the data. This positive ∆Cpex is compensated by a negative ∆Cpex of the same order at around 250 K in both binaries. At higher temperatures (up to 1200 K), ∆Cpex is zero within error for all solid solution members. As a consequence, the calorimetric entropies, Scal, show no deviation from ideal mixing behaviour within a 2σ-uncertainty for both joins. Excess entropies of mixing, ∆Sex, are thus zero for the OH-Ap–F-Ap, as well as for the OH-Ap–Cl-Ap join. The Cp–T behaviour of the OH-Ap endmember is discussed in relation to that of the F- and Cl-endmembers.

On Temperature Dependence of Excess Gibbs Energy

1999 ◽  
Vol 64 (7) ◽  
pp. 1093-1099 ◽  
Author(s):  
Ivona Malijevská ◽  
Anatol Malijevský
Keyword(s):  
Heat Capacity ◽  
Gibbs Energy ◽  
Temperature Dependence ◽  
Excess Gibbs Energy ◽  
Excess Enthalpy ◽  
Excess Heat Capacity ◽  
Wilson Equation ◽  
Excess Heat ◽  
Energy Excess ◽  
Wilson And Nrtl Equations

Temperature dependence of GE is discussed for three widely used equations linear and nonlinear in parameters. It is shown that the Wilson equation predicts always positive excess heat capacity regardless of values of its parameters. Several temperature modifications of the Redlich-Kister, Wilson and NRTL equations are discussed with respect to the sign of the excess Gibbs energy, excess enthalpy and excess heat capacity.

scholarly journals Excess Heat Capacity in Mo/Au Transition Edge Sensor Bolometric Detectors

2021 ◽  
pp. 1-1
Author(s):  
Ari David Brown ◽  
Regis Brekosky ◽  
Felipe Colazo-Petit ◽  
Matthew Greenhouse ◽  
James Hay-Wehle ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Transition Edge Sensor ◽  
Excess Heat Capacity ◽  
Excess Heat ◽  
Bolometric Detectors ◽  
Transition Edge
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