Preparation and characterization of a new series of perovskite-like structures showing evidence of structural transitions: (Methyltriphenylphosphonium)₂ BX₄, B = Mn, Co, Cu, and Hg, and × = CI/I

Abstract

A new series of perovskite-like compounds with the general chemical formula A₂BX₄ where A = methyltriphenylphosphonium, B = Mn, Co, Cu, and Hg, and × = CI/I is synthesised. IR spectra and magnetic susceptibility measurements were used to confirm the formation of the desired compounds. Differential thermal analysis reveals the presence of three structural phase transitions for the Mn compound at T= 79°, 89.09°C and 98.18°C. The latter two are first-order transitions. The Cu compound shows two transitions at 105°C and 138.6°C, the latter being of first order. The Hg compound shows a change in slope at 80°C. The dielectric permittivity of the Mn and Cu compounds as function of temperature and at different frequencies is presented. The transitions are related to the motion of the CuCI₄ ^∼2 and [CH₃(C₆H₅)₃P] ⁺.

Key Words:

• Structure phase transitions
• Dielectric measurements