Properties of the micro/nanocrystalline cellulose filled with ZrO2:Eu,F particles

Cellulose-based composites are considered as perspective materials for novel optoelectronic devices. Due to structure of cellulose it can be incorporate with various additives, in particular oxides, in order to produce composites with improved physico-chemical properties. This paper reports data on preparation and characterization of composites based on micro/nanocrystalline cellulose with ZrO
2
nanopaticles codoped with europium and fluorine ions. Morphology, dielectric and luminescence properties of the composites have been studied and analyzed together with data on properties of the starting components and literature data. It was found that samples consist of tightly packed cellulose plates of 2 – 20 µm in size. The small oxide particles are generally located inside the cellulose plates, while the larger ones and agglomerates are found on the plate's surfaces. Chemical elements analysis has shown that carbon and oxygen with average content about 71 and 29 at. %, respectively, are the main components in the most areas of the plates. Degrees of crystallinity for the samples were estimated from XRD patterns and obtained values are in the 58 - 61 % range. The photoluminescence spectra of composites consist of wide band with maxima near 480 nm related with cellulose host and weak bands of Eu
³⁺
ions luminescence peaks in 580–700 nm spectral region. In case of excitation at 393nm the CIE chromaticity coordinates of composites are moving from (x=0.211, y=0.261) for pure cellulose to (x=0.250, y=0.343) for composite with 10 wt. % of ZrO
2
:Eu,F in composite. Dielectric relaxations were observed for real and imaginary part of dielectric permittivity near – 50°C and ascribed to reorientation of methyl groups on the micro/nanocellulose crystallites surfaces.