Hello, I solved the problem with the two last line of code:
plot(xaxisn(0.01,1.69,0.01),conden3D101, xlabel=L"T/T_0", ylabel=L"N_0/N",minorticks=:false, framestyle=:box, thickness_scaling=1.7,grid=:none, linewidth = 2, guidefontsize=12,ylim=(0,1.1), legend=:topright,legendfontsize=6, label="1001 planos menos 1",linestyle=:dot)
plot!([xaxisn(0.01,1.69,0.01)],conden3D201, label="201 planos menos 1",linestyle=:dashdot)
plot!([xaxisn(0.01,1.69,0.01)],conden3D501, label="501 planos menos 1",linestyle=:dashdotdot)
plot!([xaxisn(0.01,1.69,0.01)],conden3D1001, label="1001 planos menos 1")
plot!(twinx(), xmirror=:true,grid=:false,ylim=(0,1.1),xticks = ([0.5;1;1.5;2.0;], ["","", "", ""]),yticks=([0,0.25,0.50,0.75,1.0],["","","","",""]))
plot!(size=(700,600))
And I get plots like this
its not a aestetic code but works