Connection between Unusual Lattice Thermal Expansion and Cooperative Jahn-Teller Effect in Double Perovskites LaPbMSbO6 (M = Mn, Co, Ni)

Yijia Bai; Lin Han; Jian Meng; Volodymyr Baran; Jianmin Hao; Limin Han

doi:10.1021/acs.inorgchem.8b03595

Connection between Unusual Lattice Thermal Expansion and Cooperative Jahn-Teller Effect in Double Perovskites LaPbMSbO₆ (M = Mn, Co, Ni)

Inorg Chem. 2019 Feb 18;58(4):2888-2898. doi: 10.1021/acs.inorgchem.8b03595. Epub 2019 Feb 7.

Authors

Yijia Bai^{1

2}, Lin Han³, Jian Meng³, Volodymyr Baran⁴, Jianmin Hao^{1

2}, Limin Han^{1

2}

Affiliations

¹ Chemical Engineering College , Inner Mongolia University of Technology , 49Aimin Street , Hohhot 010051 , People's Republic of China.
² Inner Mongolia Engineering Research Center for CO2 Capture and Utilization , 49 Aimin Street , Hohhot 010051 , People's Republic of China.
³ State Key Laboratory of Rare Earth Resource Utilization , Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , 5625 Renmin Street , Changchun 130022 , People's Republic of China.
⁴ Forschungsneutronenquelle Heinz Maier-Leibnitz Zentrum (MLZ) , Technische Universität München , Lichtenbergestrasse 1 , D-85747 Garching bei München , Germany.

PMID: 30730126
DOI: 10.1021/acs.inorgchem.8b03595

Abstract

Lattice thermal expansion (LTE) has been investigated in double perovskites LaPbMSbO₆ (M = Mn, Co, Ni). Ordinary LTE behavior with good thermal stability is identified for the Mn sample, whereas unusual LTE with a preferably expanded interplanar distance of (040) is revealed for Co and Ni samples. Temperature-dependent X-ray diffraction patterns ( T-XRD), Raman spectra ( T-Raman), and specific heat capacities ( T- C_p) consistently indicate that a rare isostructural displacive phase transition (IDPT) with a second-order phase transition nature is predominant near the critical temperature. Refinements of neutron powder diffraction (NPD) and in situ T-XRD data present temperature-sensitive bond parameters which are relevant to planar oxygen O1. X-ray photoelectron spectra (XPS) further confirm the Jahn-Teller (J-T) activated Co²⁺ (HS) or Ni³⁺ (HS/LS) cations at the B-site sublattice. This unusual LTE behavior could be understood by the cooperative J-T effect contributed by a Pb²⁺ ion and Co²⁺/Ni³⁺ ion from A- and B-site sublattices, respectively. The importance of 6s(Pb)-2p(O)-3d(Co/Ni) extended orbital hybridization on affecting thermal expansion behavior is highlighted on the basis of temperature-induced phonon mode softening. This study presents a microscopic description of connection between anisotropic thermal expansion and a cooperative J-T effect, which inspired exploration of thermal-mechanical coupled functional materials based on LaPbMSbO₆ double perovskites.