TY  - JOUR
AU  - Sinclair, Jordan
AU  - Flores, Marco
AU  - Brugh, Alexander M.
AU  - Rajh, Tijana
AU  - Juelsholt, Mikkel
AU  - Riaz, Aysha A.
AU  - Schlueter, Christoph
AU  - Regoutz, Anna
AU  - Birkel, Christina S.
TI  - In-Depth Analysis of the Species and Transformations during Sol Gel-Assisted V<sub>2</sub>PC Synthesis
JO  - Inorganic chemistry
VL  - 63
IS  - 23
SN  - 0020-1669
CY  - Washington, DC
PB  - American Chemical Society
M1  - PUBDB-2025-00185
SP  - 10682-10690
PY  - 2024
AB  - The sol–gel reaction mechanism of 211 MAX phases has proven to be very complex when identifying the intermediate species, chemical processes, and conversions that occur from a mixture of metal salts and gelling agent into a crystalline ternary carbide. With mostly qualitative results in the literature (Cr<sub>2</sub>GaC, Cr<sub>2</sub>GeC, and V<sub>2</sub>GeC), additional analytical techniques, including thermal analysis, powder diffraction, total scattering, and various spectroscopic methods, are necessary to unravel the identity of the chemical compounds and transformations during the reaction. Here, we demonstrate the combination of these techniques to understand the details of the sol–gel synthesis of MAX phase V<sub>2</sub>PC. The metal phosphate complexes, as well as amorphous/nanocrystalline vanadium phosphate species (V in different oxidation states), are identified at all stages of the reaction and a full schematic of the reaction process is suggested. The early amorphous vanadium species undergo multiple changes of oxidation states while organic species decompose releasing a variety of small molecule gases. Amorphous oxides, analogous to [NH<sub>4</sub>][VO<sub>2</sub>][HPO<sub>4</sub>], V<sub>2</sub>PO4O, and VO<sub>2</sub>P<sub>2</sub>O<sub>7</sub> are identified in the dried gel obtained during the early stages of the heating process (300 and 600 °C), respectively. They are carbothermally reduced starting at 900 °C and subsequently react to crystalline V<sub>2</sub>PC with the excess carbon in the reaction mixture. Through CHN analysis, we obtain an estimate of left-over amorphous carbon in the product which will guide future efforts of minimizing the amount of carbon in sol gel-produced MAX phases which is important for subsequent property studies.
LB  - PUB:(DE-HGF)16
C6  - pmid:38787450
UR  - <Go to ISI:>//WOS:001233768200001
DO  - DOI:10.1021/acs.inorgchem.4c01160
UR  - https://bib-pubdb1.desy.de/record/622099
ER  -