Lattice dynamical investigations for Raman and infrared frequencies of Te doped Bi1−xTa1−xTe2xO4; 0 ⩽ x ⩽ 0.2

• A short range force constant model based on G–F matrix method is used.
• All Raman and infrared modes have been assigned for first time for Bi1−xTa1−xTe2xO4; 0 ⩽ x ⩽ 0.2.
• Good agreement with experimental results has been obtained.
• Force constant contribution toward frequencies is determined.
• Te doping gives one mode behaviour in this compound.

We have applied short range force constant model and used normal coordinate analysis based on G–F matrix method in investigating for Raman and infrared modes in Te doped Bi1−xTa1−xTe2xO4; 0 ⩽ x ⩽ 0.2 in its orthorhombic phase. The zone centre phonons calculations is made by using six stretching and seven bending force constants in its orthorhombic phase having space group Pnna with four formula units. All zone centre modes have been assigned in this calculation for the first time. The calculated Raman and infrared wave numbers agree satisfactorily with the available experimental results. The significant contribution of each force constant towards calculated Raman and infrared wave numbers has also been made through investigating the potential energy distribution. The Te-atom is present in equal amount at Bi and Ta site in this compound. The role of tellurium atom is exhibiting one mode behaviour in the ternary compound Bi1−xTa1−xTe2xO4 (0 ⩽ x ⩽ 0.2).

A short range force constant model based on G–F matrix method is used for investigation of all Raman and infrared modes in Te doped Bi1−xTa1−xTe2xO4; 0 ⩽ x ⩽ 0.2 in its orthorhombic phase for first time.Crystal structure of BiTaO4.Figure optionsDownload as PowerPoint slide