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

Balancing the trade-off between size and stability: synergistic effects of pH and stabilizer type in sub-micron copper powder synthesis

Haijun Zhao, Jianwei Wang, Beilei Wang, Mingkun Liu, Xiaoling Ma, Ziqi Zhou, Zhenzong Quan, Huijun He, and Jie Zhu

General Research Institute for Nonferrous Metals, Beijing, China

E-mail: wangjianwei@grinm.com

Received: 24 December 2025  Accepted: 30 March 2026

Abstract:

This research addresses the challenge of balancing morphological refinement with thermal-oxidative stability in the wet chemical synthesis of sub-micron copper powders. By evaluating sodium citrate (SSC), methionine (Met), and polyvinylpyrrolidone (PVP) stabilizers under a controlled alkaline pH range (9–11), we establish a framework for precision materials design. Our findings demonstrate that while pH 11 triggers "burst nucleation" to minimize crystallite size, it concurrently lowers the thermal activation energy due to increased specific surface energy. Specifically, the SSC-stabilized system achieves a primary particle size of ~ 107.5 nm but exhibits low oxidative stability, with a peak oxidation temperature of 198.0 °C due to its permeable monodentate electrostatic barrier. In contrast, the PVP system promotes the assembly of ultrafine crystallites (~ 72.7 nm) into larger hierarchical aggregates (~ 760 nm), providing superior thermal robustness by delaying the peak oxidation temperature to 258.0 °C. This enhanced resistance is attributed to a diffusion-limited mechanism enabled by a dense, entangled polymer network. The Met system displays intermediate behavior governed by a pH-dependent coordination threshold. Ultimately, this study elucidates a critical trade-off: electrostatic stabilizers prioritize dispersive minimization for low-temperature sintering, while polymeric steric stabilizers are essential for applications requiring high thermal-oxidative resistance.

Keywords: Sub-micron copper powder; Thermal oxidative stability; Interfacial coordination; Wet chemical reduction

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04862-x

Chemical Papers 80 (7) 7887–7899 (2026)