Prediction and Synthesis of Strain Tolerant RbCuTe Crystals Based on Rotation of One-Dimensional Nano Ribbons within a Three-Dimensional Inorganic Network

Abstract

A unique possibility for a simple strain tolerant inorganic solid is envisioned whereby a set of isolated, one-dimensional (1D) nano objects are embedded in an elastically soft three-dimensional (3D) atomic matrix thus forming an interdimensional hybrid structure (IDHS). We predict theoretically that the concerted rotation of 1D nano objects could allow such IDHSs to tolerate large strain values with impunity. Searching theoretically among the 1:1:1 ABX compounds of I-I-VI composition, we identified, via first-principles thermodynamic theory, RbCuTe, which is a previously unreported but now predicted-to-be-stable compound in the MgSrSi-type structure, in space group Pnma. The predicted structure of RbCuTe consists of ribbons of copper and telluride atoms placed antipolar to one another throughout the lattice with rubidium atoms acting as a matrix. A novel synthetic adaptation utilizing liquid rubidium and vacuum annealing of the mixed elemental reagents in fused silica tubes as well as in situ (performed at the Advanced Photon Source) and ex situ structure determination confirmed the stability and predicted structure of RbCuTe. First-principles calculations then showed that the application of up to ∼30% uniaxial strain on the ground-state structure result in a buildup of internal stress not exceeding 0.5 GPa. The increase in total energy is 15-fold smaller than what is obtained for the same RbCuTe material but in structures having a contiguous set of 3D chemical bonds spanning the entire crystal. Furthermore, electronic structure calculations revealed that the HOMO is a 1D energy band localized on the CuTe ribbons and that the 1D insulating band structure is also resilient to such large strains. This combined theory and experiment study reveals a new type of strain tolerant inorganic material.

First-principles study of structural stability, electronic properties and lattice thermal conductivity of KAgX (X = S, Se, Te)

“…The absolute values of the Grüneisen parameters given by equation (8) do not give a reasonable approximation of the calculated values. In addition, the low temperature behaviour of the approximate Grüeisen parameters is opposite to the temperature dependence of the calculated values.…”

“…An-harmonicity, which is reflected in the third order derivative of the total energy with respect to atomic displacements, and for which the Grüneisen parameters are sometimes used as proxies, plays a role in phonon-phonon scattering strength [29]. In this sense, anharmonicity appears in the phonon life-times as an inverse square consistent with the inverse square dependence of the thermal conductivity on the Grüneisen parameters as suggested by equations ( 7) and (8).…”

“…In addition, the low temperature behaviour of the approximate Grüeisen parameters is opposite to the temperature dependence of the calculated values. Equations ( 7) and (8) suggest that roughly κ l ∝ 1 γ 2 . From the above discussion, this relationship cannot naively be applied in a comparison between different compounds.…”

“…Among the newly discovered potassium chalcoargentates, K 4 Ag 18 Te 11 was synthesized and characterized by Davaasuren et al [6], while monoclinic K 3 AgSe 9 was most recently (2018) synthesized by Kim et al [7]. However, there are few reports on the electronic [8] and optical properties [1] of these compounds, and many properties like elastic, phonon and thermal properties are still poorly understood.…”

Natural off-stoichiometry causes carrier doping in half-Heusler filled tetrahedral structures

“…The ABC families became recently a testing ground for theoretical material discovery by design approach [11,12,[16][17][18][19]27,28] followed by experimental validation [13,14,29,30]. There are 483 element combinations of these eighteen-electron compounds listed in Ref.…”