Zitieren Sie bitte immer diesen URN: urn:nbn:de:kobv:b43-507640
Thermodynamic properties of calcium alkali phosphates Ca(Na,K)PO4
- Calcium alkali phosphates Ca(Na,K)PO4 are main constituents of bioceramics and thermochemically produced phosphorus fertilizers because of their bioavailability. Sparse thermodynamic data are available for the endmembers CaNaPO4 and CaKPO4. In this work, the missing data were determined for the low-temperature phase modifications of the endmembers CaNaPO4 and CaKPO4 and three intermediate Ca(Na,K)PO4 compositions. Standard enthalpy of formation ranges from - 2018.3 ± 2.2 kJ mol-1 to - 2030.5 ± 2.1 kJ mol-1 and standard entropy from 137.2 ± 1.0 J mol-1 K-1 to 148.6 ± 1.0 J mol-1 K-1 from sodium endmember b-CaNaPO4 to potassium endmember b0-CaKPO4. Thermodynamic functions are calculated up to 1400 K for endmembers and the sodium-rich intermediate phase b-Ca(Na0.93K0.07)PO4. Functions above 640 K are extrapolated because of the phase transition from low- to high-temperature phase. Impurities in the synthesized intermediate phases c-Ca(Na0.4K0.6)PO4 and c-Ca Na0.35K0.65)PO4 and oneCalcium alkali phosphates Ca(Na,K)PO4 are main constituents of bioceramics and thermochemically produced phosphorus fertilizers because of their bioavailability. Sparse thermodynamic data are available for the endmembers CaNaPO4 and CaKPO4. In this work, the missing data were determined for the low-temperature phase modifications of the endmembers CaNaPO4 and CaKPO4 and three intermediate Ca(Na,K)PO4 compositions. Standard enthalpy of formation ranges from - 2018.3 ± 2.2 kJ mol-1 to - 2030.5 ± 2.1 kJ mol-1 and standard entropy from 137.2 ± 1.0 J mol-1 K-1 to 148.6 ± 1.0 J mol-1 K-1 from sodium endmember b-CaNaPO4 to potassium endmember b0-CaKPO4. Thermodynamic functions are calculated up to 1400 K for endmembers and the sodium-rich intermediate phase b-Ca(Na0.93K0.07)PO4. Functions above 640 K are extrapolated because of the phase transition from low- to high-temperature phase. Impurities in the synthesized intermediate phases c-Ca(Na0.4K0.6)PO4 and c-Ca Na0.35K0.65)PO4 and one additional phase transition around 500 K impeded the determination of high-temperature thermodynamic functions. In general, data for phase transition temperatures agree with the previously reported phase diagrams.…
Autor*innen: | Hannes HerzelORCiD, K.-D. Grevel, Franziska EmmerlingORCiD, E. Dachs, A. Benisek, Christian AdamORCiD, J. Majzlan |
---|---|
Dokumenttyp: | Zeitschriftenartikel |
Veröffentlichungsform: | Verlagsliteratur |
Sprache: | Englisch |
Titel des übergeordneten Werkes (Englisch): | Journal of Materials Science |
Jahr der Erstveröffentlichung: | 2020 |
Organisationseinheit der BAM: | 4 Material und Umwelt |
4 Material und Umwelt / 4.4 Thermochemische Reststoffbehandlung und Wertstoffrückgewinnung | |
6 Materialchemie | |
6 Materialchemie / 6.3 Strukturanalytik | |
Veröffentlichende Institution: | Bundesanstalt für Materialforschung und -prüfung (BAM) |
Verlag: | Springer |
Jahrgang/Band: | 55 |
Erste Seite: | 8477 |
Letzte Seite: | 8490 |
DDC-Klassifikation: | Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Sanitär- und Kommunaltechnik; Umwelttechnik |
Freie Schlagwörter: | Bioceramics; Entropy; Formation enthalpy; Heat capacity; Phase transformation; Phosphorus fertilizer |
Themenfelder/Aktivitätsfelder der BAM: | Umwelt |
Umwelt / Circular Economy | |
DOI: | 10.1007/s10853-020-04615-5 |
URN: | urn:nbn:de:kobv:b43-507640 |
Verfügbarkeit des Dokuments: | Datei für die Öffentlichkeit verfügbar ("Open Access") |
Datum der Freischaltung: | 13.05.2020 |
Referierte Publikation: | Ja |
Datum der Eintragung als referierte Publikation: | 13.05.2020 |
Schriftenreihen ohne Nummerierung: | Wissenschaftliche Artikel der BAM |