High pressure studies of transition metal oxides

A-Site Columnar-Ordered Perovskite CaZnV2O6 as a Pauli-Paramagnetic Metal

“…54 It would come from the fact that high-pressure synthesis can stabilize cations with high coordination numbers. 28 Similarly, an unusual 10coordinated manganese has been reported to slightly substituted A-site cation of high-pressure synthesized A-site columnarordered perovskites. 55−57 The refined structural parameters of CaZnV 2 O 6 (= Ca 0.977 Zn 0.023 ZnV 2 O 6 ) with the splitting of the A′-site Zn are listed in Table 1.…”

“…The coordination number, 10, is usual for zinc . It would come from the fact that high-pressure synthesis can stabilize cations with high coordination numbers . Similarly, an unusual 10-coordinated manganese has been reported to slightly substituted A-site cation of high-pressure synthesized A-site columnar-ordered perovskites. − The refined structural parameters of CaZnV 2 O 6 (= Ca 0.977 Zn 0.023 ZnV 2 O 6 ) with the splitting of the A′-site Zn are listed in Table .…”

“…Stoichiometric amounts of ZnO (99.99%, Rare Metallic Co.), V 2 O 3 (99.99%, Furuuchi Chemical Co.), and the obtained Ca 2 V 2 O 7 were carefully mixed and sealed in Pt capsules. Solid-state reactions were performed at 6 or 12 GPa and 1473 K for 30 min using conventional high-pressure apparatuses. − For the 6 GPa synthesis, a high-pressure cell with a graphite heater and pyrophyllite pressure media was installed in a cubic anvil-type apparatus. For the 12 GPa synthesis, a high-pressure cell with a LaCrO 3 heater and Cr-doped MgO pressure media was set in a Walker-type apparatus.…”

Anisotropic Thermal Expansion and a Second-Order Charge Order Transition in the Ferrimagnetic Dy2CuZnMn4O12 Perovskite with Triple A-Site Cation Ordering

“…The parent structure of the A 2 A′A″B 4 O 12 perovskites has P 4 2 / nmc symmetry and is formed through large tilts of the a + a + c – type . This symmetry is retained in the majority of examples of such perovskites. , The next most commonly observed symmetry is P 4 2 / n , which is produced through full or partial rock-salt-type B-cation orderings, A 2 A′A″B 2 B′ 2 O 12 . , The less common symmetries are P 4 2 mc (which is formed through polar distortions in CaMnTi 2 O 6 , CaMnTi 2– x V x O 6 , and NaYMnMnTi 4 O 12 ) and Pmmn (which is formed through layered-type B-cation ordering in RMn 3 O 6 (R = Gd to Tm) , and R 2 CuMnMn 4 O 12 (R = Dy and Y) due to partial or full charge ordering of Mn 3+ and Mn 4+ , respectively). The presence of charge-ordered structures based on the same element could suggest the existence of temperature-driven charge-(dis)­ordered transitions as observed in simple perovskites (e.g., half-doped R 3+ 0.5 A 2+ 0.5 MnO 3 ) or quadruple perovskites (e.g., ACu 3 Fe 4 O 12 ) .…”

“…1 This symmetry is retained in the majority of examples of such perovskites. 1,6 The next most commonly observed symmetry is P4 2 /n, which is produced through full or partial rock-salt-type B-cation orderings, A 2 A′A″B 2 B′ 2 O 12 . 1,6 The less common symmetries are P4 2 mc (which is formed through polar distortions in CaMnTi 2 O 6 , 7 CaMnTi 2−x V x O 6 , 8 and NaYMnMn-Ti 4 O 12 ) 9 and Pmmn (which is formed through layered-type Bcation ordering in RMn 3 O 6 (R = Gd to Tm) 10,11 and R 2 CuMnMn 4 O 12 (R = Dy and Y) 12 due to partial or full charge ordering of Mn 3+ and Mn 4+ , respectively).…”