In the previous papers, we elucidated enhancement of concentration fluctuations, phase separation, and crystallization induced by steady state or step-up shear flow, as observed by shear small-angle light scattering, optical microscopy, and birefringence, for a semidilute solution of ultrahigh molecular weight polyethylene in paraffin as an athermal solvent. However the studies were done only at a given temperature of 124 degrees C, which is higher than the nominal melting temperature of the quiescent solution T-nm (115-119 degrees C). It is crucial to extend the studies over a wider temperature range in order to generalize shear-induced phase behavior of the solution. Thus in this work we constructed a kind of phase diagram in the parameter space of temperature (T) and shear rate ((gamma) over dot). The temperature range covered was higher than T-nm, so that the phase diagram is strictly concerned with shear-induced phase behavior (i.e., without shear the solution is homogeneous and in a single-phase state). The diagram identified Regimes I-III in the T-(gamma)over dot space as will be detailed in the text. in constructing the phase diagram we found the following new points also. (i) The critical shear rate (gamma)over dot(cx) which defines the boundary between Regimes I and II was independent of T. (ii) Regime III identified previously through the (gamma) over dot dependence of the integrated scattered intensity only at a particular temperature T= 124 degrees C was further separated into two regimes of IIIa and IIIb below and above a critical temperature (147 degrees C), respectively, through the observation of the dependence as a function of T: In Regime Ilia, the sheared solution developed the optically anisotropic fibrous structures, indicative of the shear-induced crystallization triggered by the shear-induced concentration fluctuations in Regime II; In Regime IIIb, the solution is so stable that it did not show a trend of the shear-induced crystallization even at the highest shear rates accessible in this experiment, but it only showed the shear-induced phase separation. (iii) The critical shear rates (gamma) over dot(c,streak) and (gamma) over dot(cz), which define respectively the boundary between Regimes II and IIIa and that between Regimes II and IIIb, are sensitive to temperature. (C) 2009 Elsevier Ltd. All rights reserved.