Effect of external pressure and chemical substitution on the phase transitions in MnAs

Author links open overlay panelA.Ziȩba

Institute of Physics and Nuclear Techniques, Academy of Mining and Metallurgy, 30–059 Cracow, Poland

Author links open overlay panelR.Zach

Institute of Physics, Technical University of Cracow, 30–084 Cracow, Poland

Author links open overlay panelH.FjellvågA.Kjekshus

Department of Chemistry, University of Oslo, Blindern, N-0315 Oslo 3, Norway

Received 10 March 1986, Accepted 10 July 1986, Available online 17 September 2002.

Abstract

The evolution of the phase transitions in Mn1−tTtAs (T = Ti, V, Cr, Fe, Co and Ni) with t at low substitution levels is correlated with the external pressure, temperature (P, T) phase diagram of MnAs using the chemical pressure (P∗) concept. The study is based on data for transition temperatures and unit cell dimensions at atmospheric pressure and P, T phase diagrams of Mn1−tTt,As with different T and t. Chemical pressure coefficients (ranging between $\text{ϵ = −52 ± 2 kbar for T = Ti and ϵ = 133 ± 12 kbar for T = Fe, assuming P}{}^{\mathrm{\ast }}\text{= ϵt)}$ are estimated from the location of the boundary of the essentially pressure driven NiAs, F to MnP, P or MnP, Ha type transition in the individual P, T phase diagrams. Different features of the chemical pressure concept are examined, such as the relation $\text{P}{}^{\mathrm{\ast }}\text{= ϵt}$ and its break-down above a certain substitution level, the correlation between unit cell volumes and compressibility, and the non-hydrostatic character of P∗ for these non-cubic phases.

https://sci-hub.tw/https://www.sciencedirect.com/science/article/abs/pii/0022369787901442