The nature of the cooperative Jahn-Teller (JT) transition accompanied by orbital order-disorder in Nd(1-x)Ca(x)MnO(3) has been studied by high temperature (300-1200 K) synchrotron and laboratory x-ray powder diffraction in the low doping region (0≤x≤0.1). For very low doping a large temperature range of phase coexistence associated with a first-order transition has been observed, resembling a martensitic transformation. The transition appears continuous because of a gradual evolution of the volume fractions of the phases over a broad temperature interval. The first-order nature of the transition and the phase coexistence is suppressed with increasing doping.
Colin, C. V., Buurma, A. J. C., v. Zimmermann, M., & Palstra, T. T. M. (2008). Continuous first-order orbital order-disorder transition in Nd(1-x)Ca(x)MnO(3). Journal of physics: Condensed matter, 20, . https://doi.org/10.1088/0953-8984/20/43/434223