Creating a Matrix from Integrals

I have a table of integrals that I want to put in an nxn matrix. I tried doing it in the following way

phix[x_, n_] := Exp[-n \[Alpha] x^2/2] phiy[y_, m_] := Exp[-m \[Beta] y^2/2] const = {List[     Integrate[      x^2 y^2 phix[x, n1] phix[x, n2] phiy[y, m1] phiy[y, m2], {x, 0,        Infinity}, {y, 0, Infinity}], {n1, 1, 3}, {n2, 1, 3}, {m1, 1,       3}, {m2, 1, 3}]} // MatrixForm 

but what I get as output is the following, instead of the matrix form. output

I also tried to use Table instead of list, but still don’t get the output in the matrix form. I need the output as a matrix because I would like to calculate the e-values and e-vectors.

Any help would be greatly appreciated.