Low-Temperature Rapid Sintering of Dense Cubic Phase ZrW(2−x)Mo(x)O(8) Ceramics by Spark Plasma Sintering and Evaluation of Its Thermal Properties

In this study, we report a low-temperature approach involving a combination of a sol–gel hydrothermal method and spark plasma sintering (SPS) for the fabrication of cubic phase ZrW(2−x)Mo(x)O(8) (0.00 ≤ x ≤ 2.00) bulk ceramics. The cubic-ZrW(2−x)Mo(x)O(8) (0.00 ≤ x ≤ 1.50) bulk ceramics were successfully synthesized within a temperature range of 623–923 K in a very short amount of time (6–7 min), which is several hundred degrees lower than the typical solid-state approach. Meanwhile, scanning electron microscopy and density measurements revealed that the cubic-ZrW(2−x)Mo(x)O(8) (0.00 ≤ x ≤ 1.50) bulk ceramics were densified to more than 90%. X-ray diffraction (XRD) results revealed that the cubic phase ZrW(2−x)Mo(x)O(8) (0.00 ≤ x ≤ 1.5) bulk ceramics, as well as the sol–gel-hydrothermally synthesized ZrW(2−x)Mo(x)O(7)(OH)(2)·2H(2)O precursors correspond to their respective pure single phases. The bulk ceramics demonstrated negative thermal expansion characteristics, and the coefficients of negative thermal expansion were shown to be tunable in cubic-ZrW(2−x)Mo(x)O(8) bulk ceramics with respect to x value and sintering temperature. The cubic-ZrW(2−x)Mo(x)O(8) solid solution can thus have potential applications in electronic devices such as heat sinks that require regulation of thermal expansion.