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Morphology control and negative thermal expansion in cubic ZrWMoO 8 powders
Author(s) -
Liu Qinqin,
Yang Juan,
Sun Xiujuan,
Cheng Xiaog
Publication year - 2008
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200880260
Subject(s) - differential scanning calorimetry , negative thermal expansion , scanning electron microscope , thermal expansion , materials science , transmission electron microscopy , hydrothermal circulation , nanorod , crystallization , crystallography , fourier transform infrared spectroscopy , powder diffraction , chemical engineering , nanotechnology , chemistry , composite material , thermodynamics , physics , engineering
Cubic ZrWMoO 8 powders with rod‐like aggregate and thin fasciculus‐like and flower‐like rod cluster morphologies have been successfully fabricated with different amounts of (NH 4 ) 2 HPO 4 as surfactant using a hydrothermal method. X‐ray powder diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry were utilized to investigate the influence of the addition of (NH 4 ) 2 HPO 4 on the crystallization process and crystal morphology of the resulting products. The results show that the purity and the thermal expansion property of the resulting products are not influenced by the addition of (NH 4 ) 2 HPO 4 . The cubic ZrWMoO 8 powders with both rod‐like aggregate and flower‐like rod cluster morphologies show a positive thermal expansion property in the temperature range from room temperature to 120 °C, while they show a negative thermal expansion property in the temperature range from 120 °C to 700 °C. The abnormal thermal expansion property of cubic ZrWMoO 8 below 120 °C is caused by the presence of water molecules. Investigations also show that the essence of the different morphologies of the ZrWMoO 8 particles obtained is the result of the different aggregation modes of the nanorods, which act as nuclei, and the corresponding aggregation process is dominated by the addition of (NH 4 ) 2 HPO 4 and its amount. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)