ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Microwave-assisted synthesis of tungsten-based structures: effect of reaction medium composition on morphology and crystallinity

T. Guzmán-Barba, M. Estrada-Flores, C. M. Reza-SanGermán, M. E. Manríquez-Ramírez, O. G. Rojas-Valencia, C. Encarnación-Gómez, and M. G. Hernández-Cruz

Instituto Politécnico Nacional, ESIQIE, Departamento de Ingeniería Química Industrial, Mexico City, Mexico

E-mail: mestradaf0400@ipn.mx

Received: 6 July 2025  Accepted: 13 October 2025

Abstract:

This study aims to evaluate how solvent composition and the presence of a reducing agent influence the morphology and crystallinity of tungsten-based structures synthesized via a microwave-assisted solvothermal method. The goal is to understand how these variables affect particle shape, size and phase formation in sulfur-enriched tungsten compounds. Four experimental conditions were tested, two focused on the effect of solvent composition, comparing pure ethylene glycol (EG) with a water–ethylene glycol mixture (WEG, while the other two explored the influence of sodium borohydride (NaBH₄) as a reducing agent. In all cases, ammonium tetrathiotungstate (ATT) was used as the tungsten precursor, with an excess of elemental sulfur added to promote the formation of sulfur-rich phases. Synthesis reactions were carried out under microwave irradiation at 1200 W and 2.64 GHz for one minute. The resulting materials were systematically characterized using Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HR-TEM), Fourier-Transform Infrared Spectroscopy (FTIR), UV–Vis Diffuse Reflectance Spectroscopy (UV–Vis DRS) and X-ray Diffraction (XRD). SEM revealed distinct differences in morphology and particle, ranging from 0.01 to 6.5 µm. Observed morphologies included tetragonal prisms, flakes, irregular agglomerates, and flower-like structures with solvent composition being the dominant factor influencing these features. HR-TEM provided further insights into nanoscale shape, size distribution, and internal structure XRD confirmed the formation of well-defined crystalline phases, identifying tungsten trioxide (WO₃) in three samples and tungsten disulfide (WS₂) in one.

Graphical abstract

Keywords: Microwave approach; Tungsten oxide; Tungsten disulfide; Characterization

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04452-3

Chemical Papers 80 (2) 1297–1308 (2026)