Stabilizing the Frank-Kasper Phases via Binary Blends of <i>AB</i> Diblock Copolymers

The emergence of the complex Frank-Kasper phases from binary mixtures of <i>AB</i> diblock copolymers is studied using the self-consistent field theory. The relative stability of different ordered phases, including the Frank-Kasper σ and <i>A</i>15 phases containing nonspherical minority domains with different sizes, is examined by a comparison of their free energy. The resulting phase diagrams reveal that the σ phase occupies a large region in the phase space of the system. The formation mechanism of the σ phase is elucidated by the distribution of the two diblock copolymers with different lengths and compositions. In particular, the segregation of the two types of copolymers, occurring among different domains and within each domain, provides a mechanism to regulate the size and shape of the minority domains, thus enhancing the stability of the Frank-Kasper phases. These findings provide insight into understanding the formation of the Frank-Kasper phases in soft matter systems and a simple route to obtain complex ordered phases using block copolymer blends

Eu³⁺ Single-Doped Phosphor with Antithermal Quenching Behavior and Multicolor-Tunable Properties for Luminescence Thermometry

To date, non-contact luminescence thermometry methods based on fluorescence intensity ratio (FIR) technology have been studied extensively. However, designing phosphors with high relative sensitivity (Sr) has become a research hotspot. In this work, Eu3+ single-doped Ca2Sb2O7:Eu3+ phosphors with a high Sr value for dual-emitting-center luminescence thermometry are developed and proposed. The anti-thermal quenching behavior of Eu3+ originating from the energy transfer (ET) of host → Eu3+ is found and proved in the designed phosphors. Interestingly, adjustable color emission from blue to orange can be achieved. Surprisingly, the degree of the anti-thermal quenching behavior of Eu3+ gradually reduces from 240 to 127% as the Eu3+ doping content increases from 0.005 to 0.05 mol, attributed to most Eu3+ being located in the low symmetrical [Ca1O8] dodecahedral site. According to the differentiable responses of the host and Eu3+ to temperature, the maximal Sr value reaches 3.369% K–1 (383 K). Moreover, the ambient temperature can be intuitively predicted by observing the emitting color. Owing to the excellent performance in optical thermometry, color-tunable properties, and outstanding acid and alkali resistance for polydimethylsiloxane (PDMS) films, the developed Eu3+ single-doped Ca2Sb2O7:Eu3+ phosphors are expected to be prospective candidates in luminescence thermometers and LED devices in various conditions

Tunable Optical Properties and Enhanced Thermal Quenching of Non-Rare-Earth Double-Perovskite (Ba_1–<i>x</i>Sr_<i>x</i>)₂YSbO₆:Mn⁴⁺ Red Phosphors Based on Composition Modulation

Non-rare-earth Mn⁴⁺-doped double-perovskite (Ba_1–<i>x</i>Sr_<i>x</i>)₂YSbO₆:Mn⁴⁺ red-emitting phosphors with adjustable photoluminescence are fabricated via traditional high-temperature sintering reaction. The structural evolution, variation of Mn⁴⁺ local environment, luminescent properties, and thermal quenching are studied systematically. With elevation of Sr²⁺ substituting content, the major diffraction peak moves up to a higher angle gradually. Impressively, with increasing the substitution of Ba²⁺ with Sr²⁺ cation from 0 to 100%, the emission band shifts to short-wavelength in a systematic way resulting from the higher transition energy from excited states to ground states. Besides, this blue-shift appearance can be illuminated adequately using the crystal field strength. The thermal quenching of the obtained solid solution is dramatically affected by the composition, with the PL intensity increasing 16% at 423 K going from <i>x</i> = 0 to 1.0. The w-LEDs component constructed by coupling the UV-LED chip with red/green/blue phosphors demonstrate an excellent correlated color temperature (CCT) of 3404 K, as well as color rendering index (CRI) of 86.8

Three- and Eight-Fold Interpenetrated ThSi₂ Metal–Organic Frameworks Fine-Tuned by the Length of Ligand

Two new interpenetrated ThSi₂ networks, {[Ag₄(bipy)₄(ox)]·2OH·16H₂O}_<i>n</i> (<b>1</b>) and {[Ag₂(dpb)₂(ox)]·10H₂O}_<i>n</i> (<b>2</b>) (bipy = 4,4′-bipyridine, dpb = 1,4-di­(pyridin-4-yl)­benzene and Na₂ox = sodium oxalate), were constructed from bidentate pyridyl-based organic tectons incorporating ox auxiliary ligand. Interestingly, both <b>1</b> and <b>2</b> are 3D frameworks with the same ThSi₂ topology but with substantial changes in the interpenetration degrees, which are well controlled by employing the pyridyl-based ligands with different lengths. The thermal stabilities and photoluminescence behaviors of them were also discussed

Three- and Eight-Fold Interpenetrated ThSi₂ Metal–Organic Frameworks Fine-Tuned by the Length of Ligand

Two new interpenetrated ThSi₂ networks, {[Ag₄(bipy)₄(ox)]·2OH·16H₂O}_<i>n</i> (<b>1</b>) and {[Ag₂(dpb)₂(ox)]·10H₂O}_<i>n</i> (<b>2</b>) (bipy = 4,4′-bipyridine, dpb = 1,4-di­(pyridin-4-yl)­benzene and Na₂ox = sodium oxalate), were constructed from bidentate pyridyl-based organic tectons incorporating ox auxiliary ligand. Interestingly, both <b>1</b> and <b>2</b> are 3D frameworks with the same ThSi₂ topology but with substantial changes in the interpenetration degrees, which are well controlled by employing the pyridyl-based ligands with different lengths. The thermal stabilities and photoluminescence behaviors of them were also discussed