  We report magnetic susceptibility, specific heat, and Raman scattering
investigations of alpha-TeVO4 containing V-O edge-sharing chains. These chains
promote a system of ferromagnetic/antiferromagnetic spin-1/2 Heisenberg
alternating exchange chains with pronounced spin frustration. The magnetic
susceptibility and Raman scattering evidence a crossover at T* = 85 K with
different slopes of the reciprocal susceptibility and a magnetic phase
transition into a long-range-ordered state at Tc = 16 K. From Raman scattering
data a strong mutual coupling between lattice and magnetic degrees of freedom
is deduced. A comparison to model calculations and prior Raman scattering on
other chain systems yield a plausible interpretation of the microscopic
mechanism for the crossover behavior.
