Second harmonic generation in powdered strontium barium niobate crystals

The work is devoted to the investigation of phase transitions using second harmonic generation (SHG) in strontium barium niobate (SBN) powders. In the bulk SBN crystals the phase matching conditions for SHG of 1064 nm radiation cannot be satisfied. Powders of SBN crystals with average size equaled to coherence length were investigated in the paper. The obtained experimental energy dependencies are described by the quadratic law that corresponded to the second order nonlinear process. It was found that the increase of crystal temperature resulted in the reduction of SHG efficiency is caused by phase transition of the crystal from ferroelectric to paraelectric phase. The phase transition temperatures for pure and doped SBN crystals were determined.