Abstract
High-purity ultrafine platinum particles are widely used to fabricate platinum electrode oxygen sensors for automobiles and thick-film platinum resistance temperature elements. In this study, the near-spherical ultrafine Pt particles of high purity were synthesized by chemical purification, spray-drying, and ignition from crude Pt powder. Impurities in the initial Pt powder were eliminated by the 001×7 strong acid cation resin exchange column and precipitation treatment. Near-spherical (NH4)2PtCl6 particles were obtained after spray-drying, and then the microstructure and size of as-synthesized Pt particles were controlled by the ignition process. The influences of different heating temperatures during ignition treatment on the microstructure and size of Pt particles were investigated. The purity of as-synthesized Pt particles was higher than 99.999 wt%, and the average size was about 1.12 μm. The results indicate that high-purity ultrafine Pt particles can be efficiently synthesized by chemical refining.
Highlights
Ultrafine platinum powder is a kind of material with high chemical activity
A suitable Pt powder for Pt electronic paste is mainly synthesized by the liquid chemical reduction method [6, 7, 12]
The elemental analysis results of crude Pt powder, chemically precipitated powder of (NH4)2PtCl6, and as-synthesized Pt particles are shown in Table 1, where Pt and several impurity elements are listed
Summary
Ultrafine platinum powder is a kind of material with high chemical activity. The application of ultrafine Pt powder as a microelectronic material (platinum electronic paste) and catalytic material is expanding rapidly [1,2,3,4,5,6,7]. It is known that the Pt electronic paste is composed of ultrafine Pt particles, organic carriers, and binders [9]. The properties of ultrafine Pt particles have a great influence on the properties of Pt materials fabricated by Pt electronic paste. The preparation of Pt electronic paste has higher requirements for Pt particles [9, 11], such as the narrow average distribution ranging from 0.1 to 3 μm, homogeneous and near-spherical grain morphology, good dispersion and no agglomeration, low impurity content, and high density, which are strictly required. A suitable Pt powder for Pt electronic paste is mainly synthesized by the liquid chemical reduction method [6, 7, 12]. It is very important to develop an appropriate combined approach (chemical method combined with other methods) to solve the above drawbacks
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