Layered halide perovskites and double perovskites optoelectronic properties have recently been the subject of intense research. Layered double perovskites represent the merging of both worlds, and as such, have the potential to further expand the already vast space of optoelectronic properties and applications of halide perovskites. Despite having more than 40 known members, to date, only the <111>-oriented layered double perovskites: Cs4Cd1-xMnxBi2Cl12, have shown efficient photoluminescence (PL). In this work, we replaced Bi with Sb to further investigate the electronic structure and PL properties of these materials, resulting in two new families of layered inorganic perovskites alloys with full solubility. The first family, Cs4Cd1-xMnSb2Cl12, exhibits a PL emission at 605 nm ascribed to Mn 2+ centers in octahedral coordination, and a maximum photoluminescence quantum yield PLQY of 28.5%. The second family of alloys, also with full solubility, Cs4Cd0.8Mn0.2(Sb1-yBiy)2Cl12, contains a fixed amount of Mn 2+ and Cd 2+ cations but different concentrations of the trivalent metals. This variability allows the tuning of the PL emission from 603 nm to 614 nm. We show that the decreased efficiency of the Cs4Cd1-xMnxSb2Cl12family compared to Cs4Cd1-xMnxBi2Cl12, is mostly due to a decreased spin-orbit coupling in Sb and the subsequent increased electronic delocalization compared to the Bi alloys, reducing the energy transfer to Mn 2+ centers. This work lays out a roadmap to understand and achieve high photoluminescence efficiencies in layered double perovskites.

Layered halide perovskites and double perovskites optoelectronic properties have recently been the subject of intense research. Layered double perovskites represent the merging of both worlds, and as such, have the potential to further expand the already vast space of optoelectronic properties and applications of halide perovskites. Despite having more than 40 known members, to date, only the <111>-oriented layered double perovskites: Cs₄Cd₁–_xMn_x<b>Bi</b>₂Cl₁₂, have shown efficient photoluminescence (PL). In this work, we replaced Bi with Sb to further investigate the electronic structure and PL properties of these materials, resulting in two new families of layered inorganic perovskites alloys with full solubility. The first family, Cs₄Cd₁–_xMn<b>Sb</b>₂Cl₁₂, exhibits a PL emission at 605 nm ascribed to Mn²⁺ centers in octahedral coordination, and a maximum photoluminescence quantum yield PLQY of 28.5%. The second family of alloys, also with full solubility, Cs₄Cd_0.8Mn_0.2(Sb₁–_yBi_y)₂Cl₁₂, contains a fixed amount of Mn²⁺ and Cd²⁺ cations but different concentrations of the trivalent metals. This variability allows the tuning of the PL emission from 603 nm to 614 nm. We show that the decreased efficiency of the Cs₄Cd₁–_xMn_xSb₂Cl₁₂family compared to Cs₄Cd₁–_xMn_x<b>Bi</b>₂Cl₁₂, is mostly due to a decreased spin-orbit coupling in Sb and the subsequent increased electronic delocalization compared to the Bi alloys, reducing the energy transfer to Mn²⁺ centers. This work lays out a roadmap to understand and achieve high photoluminescence efficiencies in layered double perovskites.<p></p>

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This investigation demonstrates the feasibility to fabricate high quality ceramic-carbonate membranes based on mixed-conducting ceramics. Specifically, it is reported the simultaneous CO 2 /O 2 permeation and stability properties of membranes constituted by a combination of ceramic and carbonate phases, wherein the microstructure of the ceramic part is composed, in turn, of a mixture of fluorite and perovskite phases. These ceramics showed ionic and electronic conduction, and at the operation temperature, the carbonate phase of the membranes is in liquid state, which allows the transport of CO 3 2and O 2species via different mechanisms. To fabricate the membranes, the ceramic powders were uniaxially pressed in a disk shape. Then, an incipient sintering treatment was carried out in such a way that a highly porous ceramic was obtained. Afterwards, the piece is densified by the infiltration of molten carbonate. Characterization of the membranes was accomplished by SEM, XRD, and gas permeation techniques among others. Thermal and chemical stability under an atmosphere rich in CO 2 was evaluated. CO 2 /O 2 permeation and long-term stability measurements were conducted between 850 and 940 ℃. The best permeation-separation performance of membranes of about 1 mm thickness, showed a maximum permeance flux of about 4.46×10-7 mol•m-2 •s-1 •Pa-1 for CO 2 and 2.18×10-7 mol•m-2 •s-1 •Pa-1 for O 2 at 940 ℃. Membranes exhibited separation factor values of 150-991 and 49-511 for CO 2 /N 2 and O 2 /N 2 respectively in the studied temperature range. Despite long-term stability test showed certain microstructural changes in the membranes, no significant detriment on the permeation properties was observed along 100 h of continuous operation.

Ceramic–carbonate membranes have been proposed for the selective separation of CO2. In previous reports, membranes performance has been enhanced through the improvement of microstructural features and conductivity properties. Different to the aforesaid, this paper was focused on modifying the membrane surface by incorporating metallic particles to promote the involved surface reactions. First, a composite made of a Ce0.85Sm0.15O2−δ and Sm0.6Sr0.4Al0.3Fe0.7O3−δ was chemically synthesized. Then porous supports were obtained by pressing powders and sintering. Then, dense membranes were fabricated by infiltration of the supports with molten carbonates and the subsequent deposition of metallic Au–Pd particles on the membrane feed side surface. Obtained membranes were tested for CO2 separation between 700 °C and 900 °C, using different feed gas mixtures. Membranes show excellent CO2 permeance (1.72 × 10–7 mol m–2 s–1 Pa–1) operating at low CO2 partial pressure in the feed side (P CO2 = 0.115 atm), wherein about 24% of the total permeation values resulted from the surface modification approach. The permeation mechanism is discussed on the basis of these results.