One-shot wet chemical synthesis and physical properties of pyrochlore iridates A2Ir2O7, (A = Sm, Gd, Dy and Er). (May 2020)

• Record Type: Journal Article
• Authors: Rajeev, Haritha S.; Telang, Prachi; Singh, Surjeet
• Is Part Of: Solid state communications. Volume 312(2020)
• Publication Date: 2020-05
• Subjects: A. Pyrochlore iridates B. IrO2 losses -- Wet chemical synthesis C. metal-to-insulator transition E. electrical transport -- Specific heat -- Magnetic susceptibility; Solid state chemistry -- Periodicals; Solid state physics -- Periodicals; Chimie de l'état solide -- Périodiques; Physique de l'état solide -- Périodiques; 530.41
• DOI: 10.1016/j.ssc.2020.113863
• Languages: English
• ISSNs: 0038-1098

Abstract

Abstract: Iridates of the pyrochlore A2 Ir2 O7 family are interesting materials whose low-temperature properties depend sensitively on the A/Ir ratio. Due to specific difficulties, namely: (i) the volatile nature of IrO2 above 1323 K, and (ii) slow reaction kinetics between IrO2 and A2 O3 below 1323 K (where A is a members of the lanthanide series), it is challenging to prepare phase pure and stoichiometric A2 Ir2 O7 samples using the conventional solid state reaction (SSR) method in a reasonably short time. To overcome these limitations, we synthesized A2 Ir2 O7 with A = Sm, Gd, Dy, and Er using a wet chemical reaction (WCR) method in a single sintering step at T = 1273 K (a temperature well below the sublimation point of IrO2 ) for 12 h, and compared their electrical resistivity, magnetic susceptibility and specific heat with the SSR samples. We show that WCR samples exhibit metal-to-insulator & all-in all-out transitions in agreement with previous reports. The high density, low-sintering temperature, lack of IrO2 losses, and shorter preparation time are some of the attractive features of WCR method. This should be useful in exploring the true ground state properties of these materials in future. Highlights: Wet Chemical Synthesis route for the pyrochlore iridates. . Minimization of IrO2 losses and hence better stoichiometry All-in/all out ordering Metal-to-Insulator transition .