Spray‐dry synthesis of β‐Cu_1.8Zn_0.2V₂O₇ ceramic fine particles showing giant negative thermal expansion

Abstract

We used spray-dry method to synthesize fine powder of β-Cu 1.8 Zn 0.2 V 2 O 7 showing large negative thermal expansion (NTE) linearly to temperature over a wide temperature range. The NTE of β-Cu 1.8 Zn 0.2 V 2 O 7 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 μm 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. K E Y W O R D Scomposites, negative thermal expansion, particulates, spray drying SUPPORTING INFORMATIONAdditional supporting information may be found online in the Supporting Information section.How to cite this article: Takenaka K, Sato M, Mitamura M, Yokoyama Y, Katayama N, Okamoto Y. Spray-dry synthesis of β-Cu 1.8 Zn 0.2 V 2 O 7 ceramic fine particles showing giant negative thermal expansion.

Tunable giant negative thermal expansion in Ti2O3-based polycrystalline materials

“…16,17) The observed magnitude of NTE is much larger than its contraction of the unit cell volume, therefore it is also important to consider the microstructural effects due to crystalline grains, which collectively form pores and individually exhibit anisotropic expansion. 16,17) Such a microstructural origin of NTE has been also reported for Cu 1.8 Zn 0.2 V 2 O 7 , 18,19) and exploiting the microstructural effect is one of the most promising strategies to obtain large magnitude of NTE. 1) In addition to the magnitude of NTE value, controlling the temperature range of NTE is also important from the perspective of industrial applications for a wide range of usages.…”

“…1,[3][4][5] Due to intensive researches, many kinds of NTE materials have been discovered, for example, β-eucryptite, 6) ZrW 2 O 8 , 7) antiperovskite manganese nitrides, 8,9) LaCu 3 Fe 4 O 12 10) BiNiO 3 -based materials, [11][12][13] V 2 OPO 4 , 14,15) Ca 2 RuO 4 -based materials, 16,17) and Cu 1.8 Zn 0.2 V 2 O 7 . 18,19) From the view point of practical use of NTE materials, large values of NTE are desirable. Conventionally, bulk NTE due to unit cell volume contraction upon increasing temperature was discussed in ZrW 2 O 8 7) and manganese nitrides.…”

Structural phase transition and negative thermal expansion in Cu 1.8 Zn0.2V2–x P x O7 solid solutions

“…In addition to Cu 2 V 2 O 7 , 11) Cu 1.8 Zn 0.2 V 2 O 7 , 12) Cu 2 P 2 O 7 , 13) and Zn 2-x Mg x P 2 O 7 , 14) research has been expanded to solid solutions between V and P. 15) Particularly, Cu 1.8 Zn 0.2 V 2 O 7 exhibits large NTE with a coefficient of linear thermal expansion (CTE) α L = -14.4 ppm K −1 in a wide temperature T range of 100-700 K, which is assisted by the material microstructural effect peculiar to ceramic bodies. 12) Furthermore, because NTE characteristics comparable to those of bulk materials have been realized even with fine particles of 1-2 μm, 16) they are attracting a great deal of attention as thermal expansion compensators to control the thermal expansion of small areas and microcomponents such as those inside electronic devices. Pioneering attempts to use NTE materials for thermal stress relaxation in 3D integrated circuits have been reported.…”

“…Synchrotron XRD experiments were also performed at 110-760 K with the incident X-ray energy of E = 18 keV in BL5S2 beamline at Aichi Synchrotron, Japan. To verify the thermal expansion compensation capability, the powder obtained using a spraydrying method 16) was composited with epoxy resin. The epoxy resin matrix was a two-component epoxy resin adhesive prepared by mixing of the resin (EP-4100E; Adeka Corp.) and hardener (EH-105L; Adeka Corp.) in a mass ratio of 100:30.…”

“…Here, the porosity p of the epoxy resin was assumed as 0. The porosity of Cu 1.8 Zn 0.2 V 2-x P x O 7 was assumed to be p = 0.2 based on the example of other microstructural-type NTE materials 16,24) and on preliminary calculations made using Archimedes' method.…”