High‐pressure synthesis of a 12CaO·7Al₂O₃–12SrO·7Al₂O₃ solid solution

Abstract

Solid solutions of 12CaOÁ7Al 2 O 3 (C12A7) and 12SrOÁ7Al 2 O 3 (S12A7) crystals were synthesized under high pressure. X-ray diffraction patterns revealed that the lattice constants of the synthesized samples depend linearly on the compositional ratio of C12A7 and S12A7. Electron-probe X-ray microanalyses show that the chemical compositions of the crystals are represented by xC12A7Á(1Àx)S12A7 (0<x<1). These results indicate that the variation in the lattice constants is originated from a difference in the ionic radii of Ca 2+ and Sr 2+ ions. From impedance measurements, it was found that S12A7 has the highest conductivity (~1 9 10 À3 Scm À1 at 550°C) among the solid solutions in the C12A7-S12A7 system. K E Y W O R D Shigh-pressure synthesis, mayenite, solid solution, total conductivity

Synthesis and Characterization of (Ca1−xSrx)12Al14O33 Electrides

“…The Ti treatment changed the samples color from light yellow to black (see Figure 1b), and meanwhile enhanced the electron concentration and electrical conductivity. Powder XRD analysis of the electrides is shown in Figure 1c, diffraction peaks of the samples were in accordance with that of the standard diffraction data [23] (C12A7, JCPDS: 09-0413), and no change occurred before and after Ti-treatment, proving that the electrides were stable at high temperature(ß1100°C).…”

“…The lattice constant of S12A7(1.233 nm) is slightly larger than that of C12A7 (1.199 nm) and S12A7 has larger cages. [23] Therefore, if Sr substitutes Ca site, the encaged oxygen anions would be more easily released.…”

High electrical transport performance of C12A7: e– ceramics electrides on Cu‐doping

“…8 C12A7: ekeeps the original frame structure, formed by the substitution of O 2by e -. 9,10 Electrons trapped in this framework are also weakly bound and easy to emit and transition. More importantly, C12A7: eis valuable for research because of its unique energy band structure originating from the encaged electrons: cage conduction band (CCB).…”

“…The substitution of anions shows different physical properties and application prospects 8 . C12A7: e – keeps the original frame structure, formed by the substitution of O 2– by e – 9,10 . Electrons trapped in this framework are also weakly bound and easy to emit and transition.…”