Release Time:2019-03-11  Hits:

Indexed by: Journal Article

Date of Publication: 2017-10-09

Journal: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION

Included Journals: Scopus、PubMed、EI、SCIE

Volume: 56

Issue: 42

Page Number: 13052-13055

ISSN: 1433-7851

Key Words: charge transfer; hysteresis; magnetic materials; negative thermal expansion; positive thermal expansion

Abstract: It is an ongoing challenge to design and synthesize magnetic materials that undergo colossal thermal expansion and that possess potential applications as microscale or nanoscale actuators with magnetic functionality. A paramagnetic metallocyanate building block was used to construct a cyanide-bridged Fe-Co complex featuring both positive and negative colossal volumetric thermal-expansion behavior. A detailed study revealed that metal-to-metal charge transfer between 180 and 240K induced a volumetric thermal expansion coefficient of 1498 MK-1 accompanied with hysteretic spin transition. Rotation of the magnetic building blocks induced change of pi center dot center dot center dot pi interactions, resulting in a negative volume expansion coefficient of -489 MK-1, and another hysteretic magnetic transition between 300 and 350 K. This work presents a strategy for incorporating both colossal positive and negative volumetric thermal expansion with shape and magnetic memory effects in a material.