Work

Thermally induced paracelsian-to-feldspar transformation: case study of K Me Ge 3 O 8 ( Me = Al, Ga)

Year: 2025

Type: article

Abstract: Feldspars are the most common minerals in the Earth’s crust, and commonly contain trace concentrations of gallium and germanium. However, their gallium/germanium synthetic analogues are widely used, both in industrial applications and geological reconstructions. Here K Me Ge 3 O 8 ( Me = Al, Ga) compounds were synthesized using solid-state reactions and hydrothermal synthesis and studied by microprobe analysis and powder X-ray diffraction (under both ambient and high-temperature conditions). In both (Al and Ga) cases, paracelsian-like phases were the first to form, even though feldspar-like phases are predicted to be thermodynamically stable. Paracelsian-like phases are transformed irreversibly upon heating (930 ± 30 and 960 ± 30°C for KGaGe 3 O 8 and KAlGe 3 O 8 , respectively) into feldspar-like modifications. According to the obtained data, the feldspar-like modifications exhibit a higher degree of anisotropy, whereas the volume thermal expansion coefficients are higher for paracelsian-like modifications. The influence of chemical composition and topology on the crystallization process, thermal transformation and thermal expansion of feldspar- and paracelsian-like compounds is discussed.

Source: Mineralogical Magazine

DOI: 10.1180/mgm.2025.10167

Authors: Liudmila Gorelova, Maria G. Krzhizhanovskaya, Valentina A. Yukhno, Olga Yu. Shorets, Oleg S. Vereshchagin

Institutions: St Petersburg University, Institute of Chemistry of Silicates named after I.V. Grebenshchikov

Language: English

Topic: Crystal Structures and Properties

Subfield: Electronic, Optical and Magnetic Materials

Field: Materials Science

Domain: Physical Sciences

Open Access status: bronze

Funders: Saint Petersburg State University, Russian Science Foundation

Award: G1315106765