Nickel nanoparticle-stabilized room-temperature blue-phase liquid crystals

Abstract

Blue-phase liquid crystals (BPLCs) are regarded as a potential candidate for the next generation of optical devices, but they appear in a narrow temperature range, which restricts their applicability. The nanoparticle (NP) stabilization of BPLCs, is usually about either simple-cubic BP (BPII) or body-centered-cubic BP (BPI). Hence, NP-stabilized BPIIs and BPIs possessing wide temperature ranges have been scarcely reported. Here, nickel nanoparticles (Ni NPs) were synthesized and introduced into a BPLC. The concentration-dependent temperature range effects of Ni NPs on the BPLC were investigated. A trace amount of Ni NPs could stabilize the BPLC and increase the temperature ranges of BPII and BPI; this is attributable to the Ni NPs tending to be trapped at the joints of the disclination lines, as a result of the elastic interaction, stabilizing the overall lattice structure of the BPLC. When doped with 0.05 wt% Ni NPs, the mixture shows a wider range with 7.7 °C than the range with 5.9 °C of the BPLC without Ni NPs. Meanwhile, the phase sequence and range of the aforementioned phases are reproducible upon heating and cooling, which shows that the BPLCs doped with Ni NPs are thermodynamically stable.