Rattling in the Quadruple Perovskite CuCu₃V₄O₁₂

Abstract

Of particular interest is ap eculiar motion of guest atoms or ions confined to nanospace in cage compounds, called rattling.W hile rattling provides unexplored physical properties through the guest-host interactions,ithas only been observed in av ery limited class of materials.H erein, we introduce an A-site-ordered quadruple perovskite, CuCu 3 V 4 O 12 ,a sanew family of cage compounds.T his novel AA' 3 B 4 O 12 -type perovskite has been obtained by ah ighpressure synthesis technique and structurally characterized to have cubic Im3 symmetry with an ionic model of Cu 2+ Cu 2+ 3 V 4+ 4 O 12 .T he thermal displacement parameter of the A-site Cu 2+ ion is as large as U iso % 0.045 2 at 300 K, indicating its large-amplitude thermal oscillations in the oversized icosahedral cages.R emarkably,t he presence of localized phonon modes associated with rattling of the A-site Cu 2+ ion manifests itself in the low-temperature specific heat data. This work sheds new light on the structure-property relations in perovskites.

Rattling Behavior in a Simple Perovskite NaWO3

“…Our structural analysis indicates that Na1 has 12 equidistant Na1− O bonds (2.701(18) Å), whereas Na2 has four short (2.552(17) Å), four medium (2.778(17) Å), and four long (2.916(17) Å) bonds (Figure 2d). The available space of Na1 and Na2 is estimated by calculating 9,24,34,35,38 where d is the Na−O bond length and r(O 2− ) refers to the ionic radius of O 2− (=1.4 Å). 39 This yielded d cage = 1.301 Å for Na1 and 1.152, 1.378, and 1.516 Å for Na2.…”

“…Recently, Tanaka et al reported several quadruple perovskite oxides, ACu 3 V 4 O 12 (A = Mn, Cu). 23,24 In general, the A′ ions in AA′ 3 B 4 O 12 are Jahn−Teller active transition metals (e.g., Cu 2+ and Mn 3+ ), and extensive BO 6 octahedral tilting permits square-planar A′O 4 coordination. 25 The resultant A site is 12-fold coordinated typically occupied by large alkaline earth metals (e.g., La), but when it is occupied by small transition metal ions, a rattling phenomenon emerges, as seen from a large atomic displacement parameter (ADP) and Einstein-like specific heat.…”

“…25 The resultant A site is 12-fold coordinated typically occupied by large alkaline earth metals (e.g., La), but when it is occupied by small transition metal ions, a rattling phenomenon emerges, as seen from a large atomic displacement parameter (ADP) and Einstein-like specific heat. 23,24 In this paper, we report the high-pressure synthesis of a stoichiometric tungsten bronze Na x WO 3 (x = 1). Na x WO 3 has been extensively studied for decades, and a perovskite structure with a + a + a + octahedral rotation (space group: Im3̅ ) is found in a high concentration regime (x ≥ 0.8).…”

Magnetic transitions in exotic perovskites stabilized by chemical and physical pressure

“…The reduced t can cause structural distortion and thus large spontaneous electrical polarization (P S ) in noncentrosymmetric materials , 58,59 while the transition-metal-rich lattices lead to robust magnetic interplays and thus magnetoelectric effect. 15,28,51 [53][54][55] This list can be even longer. However, these exotic perovskites are thermodynamically metastable and need to be prepared at high-pressure (usually above 6 GPa) and temperature (HPT).…”

Covalency Competition in the Quadruple Perovskite CdCu3Fe4O12

“…in icosahedral coordination. [19][20][21][22][23] It was recently reported that the A-sites also tolerate a wide range of ions such as Mn 2+ and Cu + , [24][25][26] in addition to smaller rare-earth metal ions (Y 3+ , Lu 3+ , etc.). 27 The Cd ions are also incorporated into A-sites in the quadruple perovskites such as CdCu 3 Ti 4 O 12 , 28,29 31 and CdMn 7 O 12 .…”