Journal of the American Ceramic Society, Vol.103, No.4, 2757-2763, 2020
Spray-dry synthesis of beta-Cu1.8Zn0.2V2O7 ceramic fine particles showing giant negative thermal expansion
We used spray-dry method to synthesize fine powder of beta-Cu1.8Zn0.2V2O7 showing large negative thermal expansion (NTE) linearly to temperature over a wide temperature range. The NTE of beta-Cu1.8Zn0.2V2O7 is produced by microstructures consisting of voids and anisotropic thermal deformation of crystal grains in ceramics. By reducing the size of the microstructures that produce NTE, large NTE equivalent to that of bulk was realized, even for ceramic particles of about 2 mu m size. Comparison with particles produced using a conventional method demonstrates that the particle size distribution is narrow and that the particles are nearly spherical. This achievement is expected to pave the way to use of NTE materials in micrometer-scale control of thermal expansion.