紫外線遮蔽剤用単分散板状酸化セリウムマイクロ粒子の合成
及びその形態に由来する付加機能性の実現
東北大学多元物質科学研究所

殷澍、佐 藤次雄

Monodispersed spherical, rod-like, and plate-like cerium oxide particles were successfully synthesized by homogeneous
precipitation process followed by calcination in air at 400 ˚C. Monodispersed rod-like cerium carbonate precursor wasproduced at 70 ˚C for 2 h using the solution without pre-aging treatment, while monodispersed spherical precursor and platelike precursor were obtained under the same conditions after pre-aging the solution at 25 ˚C for 72 and 144 h, respectively.
In addition, micrometer sized plate-like cerium carbonate hydrate single crystal, Ce2(CO3) 3.8H2O, was successfully preparedby another facile precipitation-aging process at room temperature using sodium hydrogencarbonate as precipitate reagent,and could be converted to plate-like cerium oxide CeO2 by calcination in air at 400 ˚C. The particle size of Ce2(CO3) 3.8H2O
could be controlled by precisely adjusting pH value of the solution and/or adding organic solvents such as ethylene glycol
and various alcohols. CeO2 particles showed the same morphology and slightly decreased particle size compare with those ofrod-like, spherical and plate-like precursors. In comparison with commercial CeO2 nanoparticles, the synthesized plate-likeCeO2 particles showed lower photocatalytic and oxidation catalytic activity, higher slipping characteristic (comfort of use)and higher pearlescent (gloss value) as well as excellent UV-shielding ability, indicating the potential applications as a new
type of multifunctional cosmetic materials.

*Synthesis of Monodispersed Cerium
Oxide UV-Shielding Material with Platelike Micro-size Particles and TheirAdditional Functions Related to Their
Morphologies
Shu Yin*, Tsugio Sato
Institute of Multidisciplinary Research for
Advanced Materials, Tohoku University− 39 −

コスメトロジー研究報告 Vol.19, 2011

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紫外線遮蔽剤用単分散板状酸化セリウムマイクロ粒子の合成及びその形態に由来する付加機能性の実現（a）570nm（b）488nm
Fig.4 Size distributions of (a) as prepared spherical carbonate precursor and (b)spherical ceria
particles prepared by calcination of carbonate in air at 400℃ for 1h.

Fig.5 SEM photographs of (a) rod-like precursor synthesized in the presence oftriethanolamine, followed by (b) calcination in air at 400℃ for 1h.

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Fig.6 UV-Vis transmittance spectra of ceria thin film
consisted of particles with various morphologies. (a) and (b)spherical morphology with particle size of 350nm and700nm, respectively, (c) rod-like morphology with particle
size of 180 nm, and (d) flake-like morphology with particle
size of 5.0μm.

Fig.7 SEM photographs and ED pattern of (a) Ce (CO3) 2・8H 2O synthesized inNaHCO3 aqueous solution, (b) ceria particles synthesized by calcination of (a) in air at400 ℃ for 1h; (c) Ce (CO3) 2・8H2O synthesized in NaHCO3 –20vol% EtOH solution,and (d) ceria particles synthesized by calcination of (c) in air at 400℃ for 1h.

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紫外線遮蔽剤用単分散板状酸化セリウムマイクロ粒子の合成及びその形態に由来する付加機能性の実現

Fig.8

XRD patterns of (a) plate-like Ce(CO3)2・8H2O and (b) plate-like CeO2 particles.

Fig.9 Effect of precipitation reagents on the morphology of the products. (a) NaHCO 3 ; (b)Na2CO3 (c) K2CO3;

Fig.10 Effect of NaHCO3 concentration and reaction temperature on the morphology of theproducts. (a) 0.3M NaHCO3, 25℃ ; (b) 0.3 M NaHCO3, 75℃ ; (c) 0.3M NaHCO3,150℃ ; (d)0.45M NaHCO3, 25℃ ; (e) 0.45 M NaHCO3, 50℃ ; (f) 0.45 M NaHCO3,75℃ .

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コスメトロジー研究報告 Vol.19, 2011

Table 1 Physical properties of plate-like cerium carbonate and ceria particles.
Plate-like cerium
carbonate*
20°Average gloss level（GU）
5.8
60°Average gloss level（GU）
18.0
80°Average gloss level（GU）
8.9
Average size（μｍ）
65
Average thichness（μｍ）
1.2
Aspect ratio
55

Plate-likecerium oxide**
2.3
12.0
15.4
60
1.250

Commercial mica
powders (Y-3000)
1.9
7.2
0.8
230.3370* Synthesized in 0.008 M Ce(NO3)3・8H2O and 0.1M NaHCO3 solution.
** Synthesized by calcination of cerium carbonate in air at 400℃ for 1h.

Fig.11 Results of Ranshimat test at 120 ℃ for various nanoparticles and plate-likesamples.

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Fig.12 Dynamic friction coefficientsof various samples.

紫外線遮蔽剤用単分散板状酸化セリウムマイクロ粒子の合成及びその形態に由来する付加機能性の実現− 45 −