Spectroscopic studies ofLixFePO4andLixM0.03Fe0.97PO4(M=Cr,Cu,Al,Ti)

M\"ossbauer and Raman measurements for ${\mathrm{Li}}_{x}\mathrm{Fe}\mathrm{P}{\mathrm{O}}_{4}$ and ${\mathrm{Li}}_{x}{M}_{0.03}{\mathrm{Fe}}_{0.97}\mathrm{P}{\mathrm{O}}_{4}$ $(M=\mathrm{Cr},\mathrm{Cu},\mathrm{Al},\mathrm{Ti})$ were performed. The results for the ${\mathrm{Li}}_{0.11}\mathrm{Fe}\mathrm{P}{\mathrm{O}}_{4}$ oxide require an unknown additional contribution, besides the high-spin ${\mathrm{Fe}}^{2+}$ doublet and the high-spin ${\mathrm{Fe}}^{3+}$ doublet, for the M\"ossbauer profile to be properly accounted for. The corresponding Raman scattering suggests a two-phase material and an additional disordered structure present in the mixture. The M\"ossbauer-transformed patterns indicate the unknown doublet to be due to a disordered phase also. In addition, the observation of a high amount of ${\mathrm{Fe}}^{2+}$ sites for the low-lithium-content ${\mathrm{Li}}_{x}{M}_{0.03}{\mathrm{Fe}}_{0.97}\mathrm{P}{\mathrm{O}}_{4}$ oxides is analyzed on the basis of the electronic charge configuration of the Li-lacking octahedral units to suffer small changes upon lithium extraction.