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Raman and infrared spectra of host luminescent crystal Na_5Eu(WO_4)_4 in several different geometric con-figurations have been investigated.The symmetrical species of lattice vibrational modes of the crystal have beenanalysed by means of the site group analysis method of group theory.The experimental vibrational modes havebeen assigned to A_g,B_g,E_g,A_u and E_u of crystal factor group C_(4h).Because the energies of stretchingvibrational modes of(WO_4)~(2-)ion groups are very high(in the range of 755～940 cm~(-1)),multiphononnonradiative transitions of ~5D_2→~5D_1 and ~5D_1→~5D_0 in Eu~(3+)will occur.So it causes Eu~(3+)ions inNa_5Eu(WO_4)_4 to emit ~5D_0→~5F_j(j=1,2,3,4)emissions mainly at room temperature and the emission light ofNa_5Eu( WO_4)_4 has high red colour purity.
Raman and infrared spectra of host luminescent crystal Na_5Eu (WO_4) _4 in several different geometric con-figurations have been investigated. The symmetrical species of lattice vibrational modes of the crystal have been observed by means of the site group analysis method of group theory. vibrational modes havebeen assigned to A_g, B_g, E_g, A_u and E_u of crystal factor group C_ (4h). Because the energies of stretching vibration modes of (WO_4) ~ (2-) ion groups are very high (in the range of 755 ~ 940 cm -1), multiphononnonradiative transitions of ~ 5D_2 → ~ 5D_1 and ~ 5D_1 → ~ 5D_0 in Eu ~ (3+) will occur.So it causes Eu ~ (3+) ions inNa_5Eu (WO_4) _4 to emit ~ 5D_0 → ~ 5F_j (j = 1,2,3,4) emissions mainly at room temperature and the emission light of Na_5Eu (WO_4) _4 has high red color purity.