Determination of phase change temperature of materials from adiabatic scanning calorimetry data

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21110%2F23%3A00364743" target="_blank" >RIV/68407700:21110/23:00364743 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.1007/s10973-022-11335-2" target="_blank" >https://doi.org/10.1007/s10973-022-11335-2</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s10973-022-11335-2" target="_blank" >10.1007/s10973-022-11335-2</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Determination of phase change temperature of materials from adiabatic scanning calorimetry data

Popis výsledku v původním jazyce

Melting and other first-order phase changes usually occur in phase change materials (PCMs) within a noticeable temperature range rather than at a unique phase change temperature (Tpc). Then the enthalpy and heat capacity have rather wide jumps and peaks, respectively, spread over such ranges of temperatures. Surprisingly, wide jumps and peaks are observed even in plain and simple cases when PCMs are pure substances with negligible hysteresis and/or supercooling and the measurements are quasi-equilibrium using very slow heating/cooling rates, as in adiabatic scanning calorimetry (ASC). We show that in such cases a unique Tpc can be identified and calculated from the measured heat capacity peaks. It suffices to take into account that PCM samples do not have an ideal microstructure but are rather composed of many micro- to nano-sized domains. The heat capacity peak is then an average of individual peaks that (a) come from all domains and (b) have different shifts from Tpc for different domain sizes. Interpreting a heat capacity peak measured by ASC in this way, we present a procedure from which Tpc can be evaluated. We apply the procedure to three examples of materials using available ASC data and point out the importance of the size distribution of domains.

Název v anglickém jazyce

Determination of phase change temperature of materials from adiabatic scanning calorimetry data

Popis výsledku anglicky

Melting and other first-order phase changes usually occur in phase change materials (PCMs) within a noticeable temperature range rather than at a unique phase change temperature (Tpc). Then the enthalpy and heat capacity have rather wide jumps and peaks, respectively, spread over such ranges of temperatures. Surprisingly, wide jumps and peaks are observed even in plain and simple cases when PCMs are pure substances with negligible hysteresis and/or supercooling and the measurements are quasi-equilibrium using very slow heating/cooling rates, as in adiabatic scanning calorimetry (ASC). We show that in such cases a unique Tpc can be identified and calculated from the measured heat capacity peaks. It suffices to take into account that PCM samples do not have an ideal microstructure but are rather composed of many micro- to nano-sized domains. The heat capacity peak is then an average of individual peaks that (a) come from all domains and (b) have different shifts from Tpc for different domain sizes. Interpreting a heat capacity peak measured by ASC in this way, we present a procedure from which Tpc can be evaluated. We apply the procedure to three examples of materials using available ASC data and point out the importance of the size distribution of domains.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20501 - Materials engineering

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Thermal Analysis and Calorimetry

ISSN

1388-6150

e-ISSN

1588-2926

Svazek periodika

148

Číslo periodika v rámci svazku

4

Stát vydavatele periodika

HU - Maďarsko

Počet stran výsledku

12

Strana od-do

1693-1704

Kód UT WoS článku

000788435600001

EID výsledku v databázi Scopus

2-s2.0-85128933265