SummaryThe surface characteristics of a large set of commercial lightweight coated paper grades are explored. The quantification of the 3D structure is revealed by atomic force microscopy, laser profilometry and X-ray microtomography. This comprehensive study demonstrates the suitability of different and modern methods for assessing critical coating layer properties, thus identifying the right tools for specific structural analyses. Based on the assessment of the top and bottom surfaces of 25 commercial lightweight coated samples, three main conclusions can be drawn: (1) the facet orientation polar angle is a function of roughness, (2) skewness did not describe the surface details affecting the gloss of the commercial lightweight coated samples assessed in this study and (3) surface roughness at wavelengths below approximately 1.0 μm does not affect the paper gloss significantly. This is important knowledge for the understanding of lightweight coated paper surface structure and its properties.

Ferroelectric varactors should have high tunability at low permittivity and a working electric field to obtain better impedance matching and stable tunability. In this work, (Ba0.91Ca0.09)(SnxZr0.2−xTi0.8)O3-2 mol% CuO-1 mol% Li2CO3 (abbreviated as BCSZT100x, x = 0.05, 0.10, 0.15 and 0.20, respectively) are prepared to achieve high tunability at low permittivity and a working electric field. The tunable mechanisms are investigated based on crystal structure, micro-morphology and the permittivity-temperature spectrum. The results show that the shrink of oxygen octahedron and weaker interaction force between Sn4+ and O2− make BCSZT5 ceramic have a higher tunability value of 26.55% at low permittivity (1913) and a working electric field (7.3 kV/cm). The tunability value of BCSZT5 ceramic increases by 58%, while its permittivity decreases by 25%, compared with x = 0. Those advantages make BCSZT5 ceramic have substantial application prospects in varactors.