Influence of substituting Cu2+ for Zn2+ on the crystal structure and terahertz dielectric performances of Zn1- xCuxZrNb2O8 ( x=0.000-0.050) ceramics

A series of Zn1-xCuxZrNb2O8 (x = 0.000, 0.003, 0.010, and 0.050) ceramics with low dielectric loss and intermediate dielectric constants were synthesized by a conventional solid-phase reaction method. The terahertz dielectric performances of Zn1-xCuxZrNb2O8 (x = 0.000, 0.003, 0.010, and 0.050) ceramics have been investigated by using the Rietveld refinement method, scanning electron microscopy, Raman spectroscopy, and terahertz time-domain spectroscopy. The microscopic morphology analysis shows that the appropriate amount of Cu2+ content can make the specimen have the most uniform and medium-sized grains, which can minimize the dielectric loss in the terahertz range. Raman mapping reveals that the stress distribution is not uniform in different grains or in different regions of the same grain. The internal stresses affect the interatomic distances and influence the electronic properties, thus increasing the lattice anharmonicity and dielectric losses. In addition, the dielectric constant of the specimen in the terahertz range is mainly determined by the ionic polarization. For Zn0.997Cu0.003ZrNb2O8 sintered at 1240 degrees C, low dielectric losses (< 4 x 10(-3) @ 0.40 THz) and intermediate dielectric constant (similar to 22.95 @ 0.40 THz) were obtained, which make it promising for applications in terahertz dielectric filters.