thermal expansion of gap and gaas (chapter 1, problem 17). gap has the zinc blende structurc. thc lincar cxpansion cocfficicnt in gap has been mcasurcd as follows: n= 4.65x10-6 k-1 at 300 k; 5.27x 10-6 k-1 at 500 k; 5.97x10-6 k-1 at 800 k. (a) calculate the coefficients a, b and c in dl λ(t)-a+b(7-1.)+c(7-「)2 + . . , where to-300 k. (3 marks) (b) the lattice constant of gap, a, at 27 °c is 0.5451 nm. calculate the lattice constant at 300 °c. (3 marks) (c) the linear expansion coefficient of gaas over 200 k-1000 k is given by, λ-4.25x10-6 + (5.82x 10-9 )t-(2.82x10-12 )t2 where t is in kelvins. the lattice constant a at 300 k is 0.56533 nm. calculate the lattice constant and the density at -40 °c. (4 marks)